//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file implements the Expr constant evaluator. // // Constant expression evaluation produces four main results: // // * A success/failure flag indicating whether constant folding was successful. // This is the 'bool' return value used by most of the code in this file. A // 'false' return value indicates that constant folding has failed, and any // appropriate diagnostic has already been produced. // // * An evaluated result, valid only if constant folding has not failed. // // * A flag indicating if evaluation encountered (unevaluated) side-effects. // These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1), // where it is possible to determine the evaluated result regardless. // // * A set of notes indicating why the evaluation was not a constant expression // (under the C++11 / C++1y rules only, at the moment), or, if folding failed // too, why the expression could not be folded. // // If we are checking for a potential constant expression, failure to constant // fold a potential constant sub-expression will be indicated by a 'false' // return value (the expression could not be folded) and no diagnostic (the // expression is not necessarily non-constant). // //===----------------------------------------------------------------------===// #include "clang/AST/APValue.h" #include "clang/AST/ASTContext.h" #include "clang/AST/ASTDiagnostic.h" #include "clang/AST/ASTLambda.h" #include "clang/AST/CharUnits.h" #include "clang/AST/CurrentSourceLocExprScope.h" #include "clang/AST/CXXInheritance.h" #include "clang/AST/Expr.h" #include "clang/AST/OSLog.h" #include "clang/AST/RecordLayout.h" #include "clang/AST/StmtVisitor.h" #include "clang/AST/TypeLoc.h" #include "clang/Basic/Builtins.h" #include "clang/Basic/FixedPoint.h" #include "clang/Basic/TargetInfo.h" #include "llvm/ADT/Optional.h" #include "llvm/ADT/SmallBitVector.h" #include "llvm/Support/SaveAndRestore.h" #include "llvm/Support/raw_ostream.h" #include #include #define DEBUG_TYPE "exprconstant" using namespace clang; using llvm::APInt; using llvm::APSInt; using llvm::APFloat; using llvm::Optional; static bool IsGlobalLValue(APValue::LValueBase B); namespace { struct LValue; struct CallStackFrame; struct EvalInfo; using SourceLocExprScopeGuard = CurrentSourceLocExprScope::SourceLocExprScopeGuard; static QualType getType(APValue::LValueBase B) { if (!B) return QualType(); if (const ValueDecl *D = B.dyn_cast()) { // FIXME: It's unclear where we're supposed to take the type from, and // this actually matters for arrays of unknown bound. Eg: // // extern int arr[]; void f() { extern int arr[3]; }; // constexpr int *p = &arr[1]; // valid? // // For now, we take the array bound from the most recent declaration. for (auto *Redecl = cast(D->getMostRecentDecl()); Redecl; Redecl = cast_or_null(Redecl->getPreviousDecl())) { QualType T = Redecl->getType(); if (!T->isIncompleteArrayType()) return T; } return D->getType(); } if (B.is()) return B.getTypeInfoType(); const Expr *Base = B.get(); // For a materialized temporary, the type of the temporary we materialized // may not be the type of the expression. if (const MaterializeTemporaryExpr *MTE = dyn_cast(Base)) { SmallVector CommaLHSs; SmallVector Adjustments; const Expr *Temp = MTE->GetTemporaryExpr(); const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); // Keep any cv-qualifiers from the reference if we generated a temporary // for it directly. Otherwise use the type after adjustment. if (!Adjustments.empty()) return Inner->getType(); } return Base->getType(); } /// Get an LValue path entry, which is known to not be an array index, as a /// field declaration. static const FieldDecl *getAsField(APValue::LValuePathEntry E) { return dyn_cast_or_null(E.getAsBaseOrMember().getPointer()); } /// Get an LValue path entry, which is known to not be an array index, as a /// base class declaration. static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) { return dyn_cast_or_null(E.getAsBaseOrMember().getPointer()); } /// Determine whether this LValue path entry for a base class names a virtual /// base class. static bool isVirtualBaseClass(APValue::LValuePathEntry E) { return E.getAsBaseOrMember().getInt(); } /// Given a CallExpr, try to get the alloc_size attribute. May return null. static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) { const FunctionDecl *Callee = CE->getDirectCallee(); return Callee ? Callee->getAttr() : nullptr; } /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr. /// This will look through a single cast. /// /// Returns null if we couldn't unwrap a function with alloc_size. static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) { if (!E->getType()->isPointerType()) return nullptr; E = E->IgnoreParens(); // If we're doing a variable assignment from e.g. malloc(N), there will // probably be a cast of some kind. In exotic cases, we might also see a // top-level ExprWithCleanups. Ignore them either way. if (const auto *FE = dyn_cast(E)) E = FE->getSubExpr()->IgnoreParens(); if (const auto *Cast = dyn_cast(E)) E = Cast->getSubExpr()->IgnoreParens(); if (const auto *CE = dyn_cast(E)) return getAllocSizeAttr(CE) ? CE : nullptr; return nullptr; } /// Determines whether or not the given Base contains a call to a function /// with the alloc_size attribute. static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) { const auto *E = Base.dyn_cast(); return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E); } /// The bound to claim that an array of unknown bound has. /// The value in MostDerivedArraySize is undefined in this case. So, set it /// to an arbitrary value that's likely to loudly break things if it's used. static const uint64_t AssumedSizeForUnsizedArray = std::numeric_limits::max() / 2; /// Determines if an LValue with the given LValueBase will have an unsized /// array in its designator. /// Find the path length and type of the most-derived subobject in the given /// path, and find the size of the containing array, if any. static unsigned findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base, ArrayRef Path, uint64_t &ArraySize, QualType &Type, bool &IsArray, bool &FirstEntryIsUnsizedArray) { // This only accepts LValueBases from APValues, and APValues don't support // arrays that lack size info. assert(!isBaseAnAllocSizeCall(Base) && "Unsized arrays shouldn't appear here"); unsigned MostDerivedLength = 0; Type = getType(Base); for (unsigned I = 0, N = Path.size(); I != N; ++I) { if (Type->isArrayType()) { const ArrayType *AT = Ctx.getAsArrayType(Type); Type = AT->getElementType(); MostDerivedLength = I + 1; IsArray = true; if (auto *CAT = dyn_cast(AT)) { ArraySize = CAT->getSize().getZExtValue(); } else { assert(I == 0 && "unexpected unsized array designator"); FirstEntryIsUnsizedArray = true; ArraySize = AssumedSizeForUnsizedArray; } } else if (Type->isAnyComplexType()) { const ComplexType *CT = Type->castAs(); Type = CT->getElementType(); ArraySize = 2; MostDerivedLength = I + 1; IsArray = true; } else if (const FieldDecl *FD = getAsField(Path[I])) { Type = FD->getType(); ArraySize = 0; MostDerivedLength = I + 1; IsArray = false; } else { // Path[I] describes a base class. ArraySize = 0; IsArray = false; } } return MostDerivedLength; } // The order of this enum is important for diagnostics. enum CheckSubobjectKind { CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex, CSK_Real, CSK_Imag }; /// A path from a glvalue to a subobject of that glvalue. struct SubobjectDesignator { /// True if the subobject was named in a manner not supported by C++11. Such /// lvalues can still be folded, but they are not core constant expressions /// and we cannot perform lvalue-to-rvalue conversions on them. unsigned Invalid : 1; /// Is this a pointer one past the end of an object? unsigned IsOnePastTheEnd : 1; /// Indicator of whether the first entry is an unsized array. unsigned FirstEntryIsAnUnsizedArray : 1; /// Indicator of whether the most-derived object is an array element. unsigned MostDerivedIsArrayElement : 1; /// The length of the path to the most-derived object of which this is a /// subobject. unsigned MostDerivedPathLength : 28; /// The size of the array of which the most-derived object is an element. /// This will always be 0 if the most-derived object is not an array /// element. 0 is not an indicator of whether or not the most-derived object /// is an array, however, because 0-length arrays are allowed. /// /// If the current array is an unsized array, the value of this is /// undefined. uint64_t MostDerivedArraySize; /// The type of the most derived object referred to by this address. QualType MostDerivedType; typedef APValue::LValuePathEntry PathEntry; /// The entries on the path from the glvalue to the designated subobject. SmallVector Entries; SubobjectDesignator() : Invalid(true) {} explicit SubobjectDesignator(QualType T) : Invalid(false), IsOnePastTheEnd(false), FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), MostDerivedPathLength(0), MostDerivedArraySize(0), MostDerivedType(T) {} SubobjectDesignator(ASTContext &Ctx, const APValue &V) : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), MostDerivedPathLength(0), MostDerivedArraySize(0) { assert(V.isLValue() && "Non-LValue used to make an LValue designator?"); if (!Invalid) { IsOnePastTheEnd = V.isLValueOnePastTheEnd(); ArrayRef VEntries = V.getLValuePath(); Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); if (V.getLValueBase()) { bool IsArray = false; bool FirstIsUnsizedArray = false; MostDerivedPathLength = findMostDerivedSubobject( Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize, MostDerivedType, IsArray, FirstIsUnsizedArray); MostDerivedIsArrayElement = IsArray; FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; } } } void truncate(ASTContext &Ctx, APValue::LValueBase Base, unsigned NewLength) { if (Invalid) return; assert(Base && "cannot truncate path for null pointer"); assert(NewLength <= Entries.size() && "not a truncation"); if (NewLength == Entries.size()) return; Entries.resize(NewLength); bool IsArray = false; bool FirstIsUnsizedArray = false; MostDerivedPathLength = findMostDerivedSubobject( Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray, FirstIsUnsizedArray); MostDerivedIsArrayElement = IsArray; FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; } void setInvalid() { Invalid = true; Entries.clear(); } /// Determine whether the most derived subobject is an array without a /// known bound. bool isMostDerivedAnUnsizedArray() const { assert(!Invalid && "Calling this makes no sense on invalid designators"); return Entries.size() == 1 && FirstEntryIsAnUnsizedArray; } /// Determine what the most derived array's size is. Results in an assertion /// failure if the most derived array lacks a size. uint64_t getMostDerivedArraySize() const { assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size"); return MostDerivedArraySize; } /// Determine whether this is a one-past-the-end pointer. bool isOnePastTheEnd() const { assert(!Invalid); if (IsOnePastTheEnd) return true; if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement && Entries[MostDerivedPathLength - 1].getAsArrayIndex() == MostDerivedArraySize) return true; return false; } /// Get the range of valid index adjustments in the form /// {maximum value that can be subtracted from this pointer, /// maximum value that can be added to this pointer} std::pair validIndexAdjustments() { if (Invalid || isMostDerivedAnUnsizedArray()) return {0, 0}; // [expr.add]p4: For the purposes of these operators, a pointer to a // nonarray object behaves the same as a pointer to the first element of // an array of length one with the type of the object as its element type. bool IsArray = MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement; uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() : (uint64_t)IsOnePastTheEnd; uint64_t ArraySize = IsArray ? getMostDerivedArraySize() : (uint64_t)1; return {ArrayIndex, ArraySize - ArrayIndex}; } /// Check that this refers to a valid subobject. bool isValidSubobject() const { if (Invalid) return false; return !isOnePastTheEnd(); } /// Check that this refers to a valid subobject, and if not, produce a /// relevant diagnostic and set the designator as invalid. bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK); /// Get the type of the designated object. QualType getType(ASTContext &Ctx) const { assert(!Invalid && "invalid designator has no subobject type"); return MostDerivedPathLength == Entries.size() ? MostDerivedType : Ctx.getRecordType(getAsBaseClass(Entries.back())); } /// Update this designator to refer to the first element within this array. void addArrayUnchecked(const ConstantArrayType *CAT) { Entries.push_back(PathEntry::ArrayIndex(0)); // This is a most-derived object. MostDerivedType = CAT->getElementType(); MostDerivedIsArrayElement = true; MostDerivedArraySize = CAT->getSize().getZExtValue(); MostDerivedPathLength = Entries.size(); } /// Update this designator to refer to the first element within the array of /// elements of type T. This is an array of unknown size. void addUnsizedArrayUnchecked(QualType ElemTy) { Entries.push_back(PathEntry::ArrayIndex(0)); MostDerivedType = ElemTy; MostDerivedIsArrayElement = true; // The value in MostDerivedArraySize is undefined in this case. So, set it // to an arbitrary value that's likely to loudly break things if it's // used. MostDerivedArraySize = AssumedSizeForUnsizedArray; MostDerivedPathLength = Entries.size(); } /// Update this designator to refer to the given base or member of this /// object. void addDeclUnchecked(const Decl *D, bool Virtual = false) { Entries.push_back(APValue::BaseOrMemberType(D, Virtual)); // If this isn't a base class, it's a new most-derived object. if (const FieldDecl *FD = dyn_cast(D)) { MostDerivedType = FD->getType(); MostDerivedIsArrayElement = false; MostDerivedArraySize = 0; MostDerivedPathLength = Entries.size(); } } /// Update this designator to refer to the given complex component. void addComplexUnchecked(QualType EltTy, bool Imag) { Entries.push_back(PathEntry::ArrayIndex(Imag)); // This is technically a most-derived object, though in practice this // is unlikely to matter. MostDerivedType = EltTy; MostDerivedIsArrayElement = true; MostDerivedArraySize = 2; MostDerivedPathLength = Entries.size(); } void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E); void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, const APSInt &N); /// Add N to the address of this subobject. void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) { if (Invalid || !N) return; uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue(); if (isMostDerivedAnUnsizedArray()) { diagnoseUnsizedArrayPointerArithmetic(Info, E); // Can't verify -- trust that the user is doing the right thing (or if // not, trust that the caller will catch the bad behavior). // FIXME: Should we reject if this overflows, at least? Entries.back() = PathEntry::ArrayIndex( Entries.back().getAsArrayIndex() + TruncatedN); return; } // [expr.add]p4: For the purposes of these operators, a pointer to a // nonarray object behaves the same as a pointer to the first element of // an array of length one with the type of the object as its element type. bool IsArray = MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement; uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() : (uint64_t)IsOnePastTheEnd; uint64_t ArraySize = IsArray ? getMostDerivedArraySize() : (uint64_t)1; if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) { // Calculate the actual index in a wide enough type, so we can include // it in the note. N = N.extend(std::max(N.getBitWidth() + 1, 65)); (llvm::APInt&)N += ArrayIndex; assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index"); diagnosePointerArithmetic(Info, E, N); setInvalid(); return; } ArrayIndex += TruncatedN; assert(ArrayIndex <= ArraySize && "bounds check succeeded for out-of-bounds index"); if (IsArray) Entries.back() = PathEntry::ArrayIndex(ArrayIndex); else IsOnePastTheEnd = (ArrayIndex != 0); } }; /// A stack frame in the constexpr call stack. struct CallStackFrame { EvalInfo &Info; /// Parent - The caller of this stack frame. CallStackFrame *Caller; /// Callee - The function which was called. const FunctionDecl *Callee; /// This - The binding for the this pointer in this call, if any. const LValue *This; /// Arguments - Parameter bindings for this function call, indexed by /// parameters' function scope indices. APValue *Arguments; /// Source location information about the default argument or default /// initializer expression we're evaluating, if any. CurrentSourceLocExprScope CurSourceLocExprScope; // Note that we intentionally use std::map here so that references to // values are stable. typedef std::pair MapKeyTy; typedef std::map MapTy; /// Temporaries - Temporary lvalues materialized within this stack frame. MapTy Temporaries; /// CallLoc - The location of the call expression for this call. SourceLocation CallLoc; /// Index - The call index of this call. unsigned Index; /// The stack of integers for tracking version numbers for temporaries. SmallVector TempVersionStack = {1}; unsigned CurTempVersion = TempVersionStack.back(); unsigned getTempVersion() const { return TempVersionStack.back(); } void pushTempVersion() { TempVersionStack.push_back(++CurTempVersion); } void popTempVersion() { TempVersionStack.pop_back(); } // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact // on the overall stack usage of deeply-recursing constexpr evaluations. // (We should cache this map rather than recomputing it repeatedly.) // But let's try this and see how it goes; we can look into caching the map // as a later change. /// LambdaCaptureFields - Mapping from captured variables/this to /// corresponding data members in the closure class. llvm::DenseMap LambdaCaptureFields; FieldDecl *LambdaThisCaptureField; CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, APValue *Arguments); ~CallStackFrame(); // Return the temporary for Key whose version number is Version. APValue *getTemporary(const void *Key, unsigned Version) { MapKeyTy KV(Key, Version); auto LB = Temporaries.lower_bound(KV); if (LB != Temporaries.end() && LB->first == KV) return &LB->second; // Pair (Key,Version) wasn't found in the map. Check that no elements // in the map have 'Key' as their key. assert((LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && "Element with key 'Key' found in map"); return nullptr; } // Return the current temporary for Key in the map. APValue *getCurrentTemporary(const void *Key) { auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX)); if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) return &std::prev(UB)->second; return nullptr; } // Return the version number of the current temporary for Key. unsigned getCurrentTemporaryVersion(const void *Key) const { auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX)); if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) return std::prev(UB)->first.second; return 0; } APValue &createTemporary(const void *Key, bool IsLifetimeExtended); }; /// Temporarily override 'this'. class ThisOverrideRAII { public: ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable) : Frame(Frame), OldThis(Frame.This) { if (Enable) Frame.This = NewThis; } ~ThisOverrideRAII() { Frame.This = OldThis; } private: CallStackFrame &Frame; const LValue *OldThis; }; /// A partial diagnostic which we might know in advance that we are not going /// to emit. class OptionalDiagnostic { PartialDiagnostic *Diag; public: explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr) : Diag(Diag) {} template OptionalDiagnostic &operator<<(const T &v) { if (Diag) *Diag << v; return *this; } OptionalDiagnostic &operator<<(const APSInt &I) { if (Diag) { SmallVector Buffer; I.toString(Buffer); *Diag << StringRef(Buffer.data(), Buffer.size()); } return *this; } OptionalDiagnostic &operator<<(const APFloat &F) { if (Diag) { // FIXME: Force the precision of the source value down so we don't // print digits which are usually useless (we don't really care here if // we truncate a digit by accident in edge cases). Ideally, // APFloat::toString would automatically print the shortest // representation which rounds to the correct value, but it's a bit // tricky to implement. unsigned precision = llvm::APFloat::semanticsPrecision(F.getSemantics()); precision = (precision * 59 + 195) / 196; SmallVector Buffer; F.toString(Buffer, precision); *Diag << StringRef(Buffer.data(), Buffer.size()); } return *this; } OptionalDiagnostic &operator<<(const APFixedPoint &FX) { if (Diag) { SmallVector Buffer; FX.toString(Buffer); *Diag << StringRef(Buffer.data(), Buffer.size()); } return *this; } }; /// A cleanup, and a flag indicating whether it is lifetime-extended. class Cleanup { llvm::PointerIntPair Value; public: Cleanup(APValue *Val, bool IsLifetimeExtended) : Value(Val, IsLifetimeExtended) {} bool isLifetimeExtended() const { return Value.getInt(); } void endLifetime() { *Value.getPointer() = APValue(); } }; /// A reference to an object whose construction we are currently evaluating. struct ObjectUnderConstruction { APValue::LValueBase Base; ArrayRef Path; friend bool operator==(const ObjectUnderConstruction &LHS, const ObjectUnderConstruction &RHS) { return LHS.Base == RHS.Base && LHS.Path == RHS.Path; } friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) { return llvm::hash_combine(Obj.Base, Obj.Path); } }; enum class ConstructionPhase { None, Bases, AfterBases }; } namespace llvm { template<> struct DenseMapInfo { using Base = DenseMapInfo; static ObjectUnderConstruction getEmptyKey() { return {Base::getEmptyKey(), {}}; } static ObjectUnderConstruction getTombstoneKey() { return {Base::getTombstoneKey(), {}}; } static unsigned getHashValue(const ObjectUnderConstruction &Object) { return hash_value(Object); } static bool isEqual(const ObjectUnderConstruction &LHS, const ObjectUnderConstruction &RHS) { return LHS == RHS; } }; } namespace { /// EvalInfo - This is a private struct used by the evaluator to capture /// information about a subexpression as it is folded. It retains information /// about the AST context, but also maintains information about the folded /// expression. /// /// If an expression could be evaluated, it is still possible it is not a C /// "integer constant expression" or constant expression. If not, this struct /// captures information about how and why not. /// /// One bit of information passed *into* the request for constant folding /// indicates whether the subexpression is "evaluated" or not according to C /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can /// evaluate the expression regardless of what the RHS is, but C only allows /// certain things in certain situations. struct EvalInfo { ASTContext &Ctx; /// EvalStatus - Contains information about the evaluation. Expr::EvalStatus &EvalStatus; /// CurrentCall - The top of the constexpr call stack. CallStackFrame *CurrentCall; /// CallStackDepth - The number of calls in the call stack right now. unsigned CallStackDepth; /// NextCallIndex - The next call index to assign. unsigned NextCallIndex; /// StepsLeft - The remaining number of evaluation steps we're permitted /// to perform. This is essentially a limit for the number of statements /// we will evaluate. unsigned StepsLeft; /// BottomFrame - The frame in which evaluation started. This must be /// initialized after CurrentCall and CallStackDepth. CallStackFrame BottomFrame; /// A stack of values whose lifetimes end at the end of some surrounding /// evaluation frame. llvm::SmallVector CleanupStack; /// EvaluatingDecl - This is the declaration whose initializer is being /// evaluated, if any. APValue::LValueBase EvaluatingDecl; /// EvaluatingDeclValue - This is the value being constructed for the /// declaration whose initializer is being evaluated, if any. APValue *EvaluatingDeclValue; /// Set of objects that are currently being constructed. llvm::DenseMap ObjectsUnderConstruction; struct EvaluatingConstructorRAII { EvalInfo &EI; ObjectUnderConstruction Object; bool DidInsert; EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object, bool HasBases) : EI(EI), Object(Object) { DidInsert = EI.ObjectsUnderConstruction .insert({Object, HasBases ? ConstructionPhase::Bases : ConstructionPhase::AfterBases}) .second; } void finishedConstructingBases() { EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases; } ~EvaluatingConstructorRAII() { if (DidInsert) EI.ObjectsUnderConstruction.erase(Object); } }; ConstructionPhase isEvaluatingConstructor(APValue::LValueBase Base, ArrayRef Path) { return ObjectsUnderConstruction.lookup({Base, Path}); } /// If we're currently speculatively evaluating, the outermost call stack /// depth at which we can mutate state, otherwise 0. unsigned SpeculativeEvaluationDepth = 0; /// The current array initialization index, if we're performing array /// initialization. uint64_t ArrayInitIndex = -1; /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further /// notes attached to it will also be stored, otherwise they will not be. bool HasActiveDiagnostic; /// Have we emitted a diagnostic explaining why we couldn't constant /// fold (not just why it's not strictly a constant expression)? bool HasFoldFailureDiagnostic; /// Whether or not we're in a context where the front end requires a /// constant value. bool InConstantContext; /// Whether we're checking that an expression is a potential constant /// expression. If so, do not fail on constructs that could become constant /// later on (such as a use of an undefined global). bool CheckingPotentialConstantExpression = false; /// Whether we're checking for an expression that has undefined behavior. /// If so, we will produce warnings if we encounter an operation that is /// always undefined. bool CheckingForUndefinedBehavior = false; enum EvaluationMode { /// Evaluate as a constant expression. Stop if we find that the expression /// is not a constant expression. EM_ConstantExpression, /// Evaluate as a constant expression. Stop if we find that the expression /// is not a constant expression. Some expressions can be retried in the /// optimizer if we don't constant fold them here, but in an unevaluated /// context we try to fold them immediately since the optimizer never /// gets a chance to look at it. EM_ConstantExpressionUnevaluated, /// Fold the expression to a constant. Stop if we hit a side-effect that /// we can't model. EM_ConstantFold, /// Evaluate in any way we know how. Don't worry about side-effects that /// can't be modeled. EM_IgnoreSideEffects, } EvalMode; /// Are we checking whether the expression is a potential constant /// expression? bool checkingPotentialConstantExpression() const { return CheckingPotentialConstantExpression; } /// Are we checking an expression for overflow? // FIXME: We should check for any kind of undefined or suspicious behavior // in such constructs, not just overflow. bool checkingForUndefinedBehavior() { return CheckingForUndefinedBehavior; } EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) : Ctx(const_cast(C)), EvalStatus(S), CurrentCall(nullptr), CallStackDepth(0), NextCallIndex(1), StepsLeft(getLangOpts().ConstexprStepLimit), BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr), EvaluatingDecl((const ValueDecl *)nullptr), EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false), HasFoldFailureDiagnostic(false), InConstantContext(false), EvalMode(Mode) {} void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) { EvaluatingDecl = Base; EvaluatingDeclValue = &Value; } const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); } bool CheckCallLimit(SourceLocation Loc) { // Don't perform any constexpr calls (other than the call we're checking) // when checking a potential constant expression. if (checkingPotentialConstantExpression() && CallStackDepth > 1) return false; if (NextCallIndex == 0) { // NextCallIndex has wrapped around. FFDiag(Loc, diag::note_constexpr_call_limit_exceeded); return false; } if (CallStackDepth <= getLangOpts().ConstexprCallDepth) return true; FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded) << getLangOpts().ConstexprCallDepth; return false; } std::pair getCallFrameAndDepth(unsigned CallIndex) { assert(CallIndex && "no call index in getCallFrameAndDepth"); // We will eventually hit BottomFrame, which has Index 1, so Frame can't // be null in this loop. unsigned Depth = CallStackDepth; CallStackFrame *Frame = CurrentCall; while (Frame->Index > CallIndex) { Frame = Frame->Caller; --Depth; } if (Frame->Index == CallIndex) return {Frame, Depth}; return {nullptr, 0}; } bool nextStep(const Stmt *S) { if (!StepsLeft) { FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded); return false; } --StepsLeft; return true; } private: /// Add a diagnostic to the diagnostics list. PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) { PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator()); EvalStatus.Diag->push_back(std::make_pair(Loc, PD)); return EvalStatus.Diag->back().second; } /// Add notes containing a call stack to the current point of evaluation. void addCallStack(unsigned Limit); private: OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId, unsigned ExtraNotes, bool IsCCEDiag) { if (EvalStatus.Diag) { // If we have a prior diagnostic, it will be noting that the expression // isn't a constant expression. This diagnostic is more important, // unless we require this evaluation to produce a constant expression. // // FIXME: We might want to show both diagnostics to the user in // EM_ConstantFold mode. if (!EvalStatus.Diag->empty()) { switch (EvalMode) { case EM_ConstantFold: case EM_IgnoreSideEffects: if (!HasFoldFailureDiagnostic) break; // We've already failed to fold something. Keep that diagnostic. LLVM_FALLTHROUGH; case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: HasActiveDiagnostic = false; return OptionalDiagnostic(); } } unsigned CallStackNotes = CallStackDepth - 1; unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); if (Limit) CallStackNotes = std::min(CallStackNotes, Limit + 1); if (checkingPotentialConstantExpression()) CallStackNotes = 0; HasActiveDiagnostic = true; HasFoldFailureDiagnostic = !IsCCEDiag; EvalStatus.Diag->clear(); EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes); addDiag(Loc, DiagId); if (!checkingPotentialConstantExpression()) addCallStack(Limit); return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second); } HasActiveDiagnostic = false; return OptionalDiagnostic(); } public: // Diagnose that the evaluation could not be folded (FF => FoldFailure) OptionalDiagnostic FFDiag(SourceLocation Loc, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { return Diag(Loc, DiagId, ExtraNotes, false); } OptionalDiagnostic FFDiag(const Expr *E, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { if (EvalStatus.Diag) return Diag(E->getExprLoc(), DiagId, ExtraNotes, /*IsCCEDiag*/false); HasActiveDiagnostic = false; return OptionalDiagnostic(); } /// Diagnose that the evaluation does not produce a C++11 core constant /// expression. /// /// FIXME: Stop evaluating if we're in EM_ConstantExpression mode /// and we produce one of these. OptionalDiagnostic CCEDiag(SourceLocation Loc, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { // Don't override a previous diagnostic. Don't bother collecting // diagnostics if we're evaluating for overflow. if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { HasActiveDiagnostic = false; return OptionalDiagnostic(); } return Diag(Loc, DiagId, ExtraNotes, true); } OptionalDiagnostic CCEDiag(const Expr *E, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { return CCEDiag(E->getExprLoc(), DiagId, ExtraNotes); } /// Add a note to a prior diagnostic. OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) { if (!HasActiveDiagnostic) return OptionalDiagnostic(); return OptionalDiagnostic(&addDiag(Loc, DiagId)); } /// Add a stack of notes to a prior diagnostic. void addNotes(ArrayRef Diags) { if (HasActiveDiagnostic) { EvalStatus.Diag->insert(EvalStatus.Diag->end(), Diags.begin(), Diags.end()); } } /// Should we continue evaluation after encountering a side-effect that we /// couldn't model? bool keepEvaluatingAfterSideEffect() { switch (EvalMode) { case EM_IgnoreSideEffects: return true; case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: case EM_ConstantFold: // By default, assume any side effect might be valid in some other // evaluation of this expression from a different context. return checkingPotentialConstantExpression() || checkingForUndefinedBehavior(); } llvm_unreachable("Missed EvalMode case"); } /// Note that we have had a side-effect, and determine whether we should /// keep evaluating. bool noteSideEffect() { EvalStatus.HasSideEffects = true; return keepEvaluatingAfterSideEffect(); } /// Should we continue evaluation after encountering undefined behavior? bool keepEvaluatingAfterUndefinedBehavior() { switch (EvalMode) { case EM_IgnoreSideEffects: case EM_ConstantFold: return true; case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: return checkingForUndefinedBehavior(); } llvm_unreachable("Missed EvalMode case"); } /// Note that we hit something that was technically undefined behavior, but /// that we can evaluate past it (such as signed overflow or floating-point /// division by zero.) bool noteUndefinedBehavior() { EvalStatus.HasUndefinedBehavior = true; return keepEvaluatingAfterUndefinedBehavior(); } /// Should we continue evaluation as much as possible after encountering a /// construct which can't be reduced to a value? bool keepEvaluatingAfterFailure() { if (!StepsLeft) return false; switch (EvalMode) { case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: case EM_ConstantFold: case EM_IgnoreSideEffects: return checkingPotentialConstantExpression() || checkingForUndefinedBehavior(); } llvm_unreachable("Missed EvalMode case"); } /// Notes that we failed to evaluate an expression that other expressions /// directly depend on, and determine if we should keep evaluating. This /// should only be called if we actually intend to keep evaluating. /// /// Call noteSideEffect() instead if we may be able to ignore the value that /// we failed to evaluate, e.g. if we failed to evaluate Foo() in: /// /// (Foo(), 1) // use noteSideEffect /// (Foo() || true) // use noteSideEffect /// Foo() + 1 // use noteFailure LLVM_NODISCARD bool noteFailure() { // Failure when evaluating some expression often means there is some // subexpression whose evaluation was skipped. Therefore, (because we // don't track whether we skipped an expression when unwinding after an // evaluation failure) every evaluation failure that bubbles up from a // subexpression implies that a side-effect has potentially happened. We // skip setting the HasSideEffects flag to true until we decide to // continue evaluating after that point, which happens here. bool KeepGoing = keepEvaluatingAfterFailure(); EvalStatus.HasSideEffects |= KeepGoing; return KeepGoing; } class ArrayInitLoopIndex { EvalInfo &Info; uint64_t OuterIndex; public: ArrayInitLoopIndex(EvalInfo &Info) : Info(Info), OuterIndex(Info.ArrayInitIndex) { Info.ArrayInitIndex = 0; } ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; } operator uint64_t&() { return Info.ArrayInitIndex; } }; }; /// Object used to treat all foldable expressions as constant expressions. struct FoldConstant { EvalInfo &Info; bool Enabled; bool HadNoPriorDiags; EvalInfo::EvaluationMode OldMode; explicit FoldConstant(EvalInfo &Info, bool Enabled) : Info(Info), Enabled(Enabled), HadNoPriorDiags(Info.EvalStatus.Diag && Info.EvalStatus.Diag->empty() && !Info.EvalStatus.HasSideEffects), OldMode(Info.EvalMode) { if (Enabled) Info.EvalMode = EvalInfo::EM_ConstantFold; } void keepDiagnostics() { Enabled = false; } ~FoldConstant() { if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && !Info.EvalStatus.HasSideEffects) Info.EvalStatus.Diag->clear(); Info.EvalMode = OldMode; } }; /// RAII object used to set the current evaluation mode to ignore /// side-effects. struct IgnoreSideEffectsRAII { EvalInfo &Info; EvalInfo::EvaluationMode OldMode; explicit IgnoreSideEffectsRAII(EvalInfo &Info) : Info(Info), OldMode(Info.EvalMode) { Info.EvalMode = EvalInfo::EM_IgnoreSideEffects; } ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; } }; /// RAII object used to optionally suppress diagnostics and side-effects from /// a speculative evaluation. class SpeculativeEvaluationRAII { EvalInfo *Info = nullptr; Expr::EvalStatus OldStatus; unsigned OldSpeculativeEvaluationDepth; void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) { Info = Other.Info; OldStatus = Other.OldStatus; OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth; Other.Info = nullptr; } void maybeRestoreState() { if (!Info) return; Info->EvalStatus = OldStatus; Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth; } public: SpeculativeEvaluationRAII() = default; SpeculativeEvaluationRAII( EvalInfo &Info, SmallVectorImpl *NewDiag = nullptr) : Info(&Info), OldStatus(Info.EvalStatus), OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) { Info.EvalStatus.Diag = NewDiag; Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1; } SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete; SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) { moveFromAndCancel(std::move(Other)); } SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) { maybeRestoreState(); moveFromAndCancel(std::move(Other)); return *this; } ~SpeculativeEvaluationRAII() { maybeRestoreState(); } }; /// RAII object wrapping a full-expression or block scope, and handling /// the ending of the lifetime of temporaries created within it. template class ScopeRAII { EvalInfo &Info; unsigned OldStackSize; public: ScopeRAII(EvalInfo &Info) : Info(Info), OldStackSize(Info.CleanupStack.size()) { // Push a new temporary version. This is needed to distinguish between // temporaries created in different iterations of a loop. Info.CurrentCall->pushTempVersion(); } ~ScopeRAII() { // Body moved to a static method to encourage the compiler to inline away // instances of this class. cleanup(Info, OldStackSize); Info.CurrentCall->popTempVersion(); } private: static void cleanup(EvalInfo &Info, unsigned OldStackSize) { unsigned NewEnd = OldStackSize; for (unsigned I = OldStackSize, N = Info.CleanupStack.size(); I != N; ++I) { if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) { // Full-expression cleanup of a lifetime-extended temporary: nothing // to do, just move this cleanup to the right place in the stack. std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]); ++NewEnd; } else { // End the lifetime of the object. Info.CleanupStack[I].endLifetime(); } } Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd, Info.CleanupStack.end()); } }; typedef ScopeRAII BlockScopeRAII; typedef ScopeRAII FullExpressionRAII; } bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { if (Invalid) return false; if (isOnePastTheEnd()) { Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) << CSK; setInvalid(); return false; } // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there // must actually be at least one array element; even a VLA cannot have a // bound of zero. And if our index is nonzero, we already had a CCEDiag. return true; } void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E) { Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed); // Do not set the designator as invalid: we can represent this situation, // and correct handling of __builtin_object_size requires us to do so. } void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, const APSInt &N) { // If we're complaining, we must be able to statically determine the size of // the most derived array. if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement) Info.CCEDiag(E, diag::note_constexpr_array_index) << N << /*array*/ 0 << static_cast(getMostDerivedArraySize()); else Info.CCEDiag(E, diag::note_constexpr_array_index) << N << /*non-array*/ 1; setInvalid(); } CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, APValue *Arguments) : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This), Arguments(Arguments), CallLoc(CallLoc), Index(Info.NextCallIndex++) { Info.CurrentCall = this; ++Info.CallStackDepth; } CallStackFrame::~CallStackFrame() { assert(Info.CurrentCall == this && "calls retired out of order"); --Info.CallStackDepth; Info.CurrentCall = Caller; } APValue &CallStackFrame::createTemporary(const void *Key, bool IsLifetimeExtended) { unsigned Version = Info.CurrentCall->getTempVersion(); APValue &Result = Temporaries[MapKeyTy(Key, Version)]; assert(Result.isAbsent() && "temporary created multiple times"); Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended)); return Result; } static void describeCall(CallStackFrame *Frame, raw_ostream &Out); void EvalInfo::addCallStack(unsigned Limit) { // Determine which calls to skip, if any. unsigned ActiveCalls = CallStackDepth - 1; unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart; if (Limit && Limit < ActiveCalls) { SkipStart = Limit / 2 + Limit % 2; SkipEnd = ActiveCalls - Limit / 2; } // Walk the call stack and add the diagnostics. unsigned CallIdx = 0; for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame; Frame = Frame->Caller, ++CallIdx) { // Skip this call? if (CallIdx >= SkipStart && CallIdx < SkipEnd) { if (CallIdx == SkipStart) { // Note that we're skipping calls. addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed) << unsigned(ActiveCalls - Limit); } continue; } // Use a different note for an inheriting constructor, because from the // user's perspective it's not really a function at all. if (auto *CD = dyn_cast_or_null(Frame->Callee)) { if (CD->isInheritingConstructor()) { addDiag(Frame->CallLoc, diag::note_constexpr_inherited_ctor_call_here) << CD->getParent(); continue; } } SmallVector Buffer; llvm::raw_svector_ostream Out(Buffer); describeCall(Frame, Out); addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); } } /// Kinds of access we can perform on an object, for diagnostics. Note that /// we consider a member function call to be a kind of access, even though /// it is not formally an access of the object, because it has (largely) the /// same set of semantic restrictions. enum AccessKinds { AK_Read, AK_Assign, AK_Increment, AK_Decrement, AK_MemberCall, AK_DynamicCast, AK_TypeId, }; static bool isModification(AccessKinds AK) { switch (AK) { case AK_Read: case AK_MemberCall: case AK_DynamicCast: case AK_TypeId: return false; case AK_Assign: case AK_Increment: case AK_Decrement: return true; } llvm_unreachable("unknown access kind"); } /// Is this an access per the C++ definition? static bool isFormalAccess(AccessKinds AK) { return AK == AK_Read || isModification(AK); } namespace { struct ComplexValue { private: bool IsInt; public: APSInt IntReal, IntImag; APFloat FloatReal, FloatImag; ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {} void makeComplexFloat() { IsInt = false; } bool isComplexFloat() const { return !IsInt; } APFloat &getComplexFloatReal() { return FloatReal; } APFloat &getComplexFloatImag() { return FloatImag; } void makeComplexInt() { IsInt = true; } bool isComplexInt() const { return IsInt; } APSInt &getComplexIntReal() { return IntReal; } APSInt &getComplexIntImag() { return IntImag; } void moveInto(APValue &v) const { if (isComplexFloat()) v = APValue(FloatReal, FloatImag); else v = APValue(IntReal, IntImag); } void setFrom(const APValue &v) { assert(v.isComplexFloat() || v.isComplexInt()); if (v.isComplexFloat()) { makeComplexFloat(); FloatReal = v.getComplexFloatReal(); FloatImag = v.getComplexFloatImag(); } else { makeComplexInt(); IntReal = v.getComplexIntReal(); IntImag = v.getComplexIntImag(); } } }; struct LValue { APValue::LValueBase Base; CharUnits Offset; SubobjectDesignator Designator; bool IsNullPtr : 1; bool InvalidBase : 1; const APValue::LValueBase getLValueBase() const { return Base; } CharUnits &getLValueOffset() { return Offset; } const CharUnits &getLValueOffset() const { return Offset; } SubobjectDesignator &getLValueDesignator() { return Designator; } const SubobjectDesignator &getLValueDesignator() const { return Designator;} bool isNullPointer() const { return IsNullPtr;} unsigned getLValueCallIndex() const { return Base.getCallIndex(); } unsigned getLValueVersion() const { return Base.getVersion(); } void moveInto(APValue &V) const { if (Designator.Invalid) V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr); else { assert(!InvalidBase && "APValues can't handle invalid LValue bases"); V = APValue(Base, Offset, Designator.Entries, Designator.IsOnePastTheEnd, IsNullPtr); } } void setFrom(ASTContext &Ctx, const APValue &V) { assert(V.isLValue() && "Setting LValue from a non-LValue?"); Base = V.getLValueBase(); Offset = V.getLValueOffset(); InvalidBase = false; Designator = SubobjectDesignator(Ctx, V); IsNullPtr = V.isNullPointer(); } void set(APValue::LValueBase B, bool BInvalid = false) { #ifndef NDEBUG // We only allow a few types of invalid bases. Enforce that here. if (BInvalid) { const auto *E = B.get(); assert((isa(E) || tryUnwrapAllocSizeCall(E)) && "Unexpected type of invalid base"); } #endif Base = B; Offset = CharUnits::fromQuantity(0); InvalidBase = BInvalid; Designator = SubobjectDesignator(getType(B)); IsNullPtr = false; } void setNull(QualType PointerTy, uint64_t TargetVal) { Base = (Expr *)nullptr; Offset = CharUnits::fromQuantity(TargetVal); InvalidBase = false; Designator = SubobjectDesignator(PointerTy->getPointeeType()); IsNullPtr = true; } void setInvalid(APValue::LValueBase B, unsigned I = 0) { set(B, true); } private: // Check that this LValue is not based on a null pointer. If it is, produce // a diagnostic and mark the designator as invalid. template bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) { if (Designator.Invalid) return false; if (IsNullPtr) { GenDiag(); Designator.setInvalid(); return false; } return true; } public: bool checkNullPointer(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { return checkNullPointerDiagnosingWith([&Info, E, CSK] { Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK; }); } bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E, AccessKinds AK) { return checkNullPointerDiagnosingWith([&Info, E, AK] { Info.FFDiag(E, diag::note_constexpr_access_null) << AK; }); } // Check this LValue refers to an object. If not, set the designator to be // invalid and emit a diagnostic. bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) && Designator.checkSubobject(Info, E, CSK); } void addDecl(EvalInfo &Info, const Expr *E, const Decl *D, bool Virtual = false) { if (checkSubobject(Info, E, isa(D) ? CSK_Field : CSK_Base)) Designator.addDeclUnchecked(D, Virtual); } void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) { if (!Designator.Entries.empty()) { Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array); Designator.setInvalid(); return; } if (checkSubobject(Info, E, CSK_ArrayToPointer)) { assert(getType(Base)->isPointerType() || getType(Base)->isArrayType()); Designator.FirstEntryIsAnUnsizedArray = true; Designator.addUnsizedArrayUnchecked(ElemTy); } } void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { if (checkSubobject(Info, E, CSK_ArrayToPointer)) Designator.addArrayUnchecked(CAT); } void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) Designator.addComplexUnchecked(EltTy, Imag); } void clearIsNullPointer() { IsNullPtr = false; } void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E, const APSInt &Index, CharUnits ElementSize) { // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB, // but we're not required to diagnose it and it's valid in C++.) if (!Index) return; // Compute the new offset in the appropriate width, wrapping at 64 bits. // FIXME: When compiling for a 32-bit target, we should use 32-bit // offsets. uint64_t Offset64 = Offset.getQuantity(); uint64_t ElemSize64 = ElementSize.getQuantity(); uint64_t Index64 = Index.extOrTrunc(64).getZExtValue(); Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64); if (checkNullPointer(Info, E, CSK_ArrayIndex)) Designator.adjustIndex(Info, E, Index); clearIsNullPointer(); } void adjustOffset(CharUnits N) { Offset += N; if (N.getQuantity()) clearIsNullPointer(); } }; struct MemberPtr { MemberPtr() {} explicit MemberPtr(const ValueDecl *Decl) : DeclAndIsDerivedMember(Decl, false), Path() {} /// The member or (direct or indirect) field referred to by this member /// pointer, or 0 if this is a null member pointer. const ValueDecl *getDecl() const { return DeclAndIsDerivedMember.getPointer(); } /// Is this actually a member of some type derived from the relevant class? bool isDerivedMember() const { return DeclAndIsDerivedMember.getInt(); } /// Get the class which the declaration actually lives in. const CXXRecordDecl *getContainingRecord() const { return cast( DeclAndIsDerivedMember.getPointer()->getDeclContext()); } void moveInto(APValue &V) const { V = APValue(getDecl(), isDerivedMember(), Path); } void setFrom(const APValue &V) { assert(V.isMemberPointer()); DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); Path.clear(); ArrayRef P = V.getMemberPointerPath(); Path.insert(Path.end(), P.begin(), P.end()); } /// DeclAndIsDerivedMember - The member declaration, and a flag indicating /// whether the member is a member of some class derived from the class type /// of the member pointer. llvm::PointerIntPair DeclAndIsDerivedMember; /// Path - The path of base/derived classes from the member declaration's /// class (exclusive) to the class type of the member pointer (inclusive). SmallVector Path; /// Perform a cast towards the class of the Decl (either up or down the /// hierarchy). bool castBack(const CXXRecordDecl *Class) { assert(!Path.empty()); const CXXRecordDecl *Expected; if (Path.size() >= 2) Expected = Path[Path.size() - 2]; else Expected = getContainingRecord(); if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), // if B does not contain the original member and is not a base or // derived class of the class containing the original member, the result // of the cast is undefined. // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to // (D::*). We consider that to be a language defect. return false; } Path.pop_back(); return true; } /// Perform a base-to-derived member pointer cast. bool castToDerived(const CXXRecordDecl *Derived) { if (!getDecl()) return true; if (!isDerivedMember()) { Path.push_back(Derived); return true; } if (!castBack(Derived)) return false; if (Path.empty()) DeclAndIsDerivedMember.setInt(false); return true; } /// Perform a derived-to-base member pointer cast. bool castToBase(const CXXRecordDecl *Base) { if (!getDecl()) return true; if (Path.empty()) DeclAndIsDerivedMember.setInt(true); if (isDerivedMember()) { Path.push_back(Base); return true; } return castBack(Base); } }; /// Compare two member pointers, which are assumed to be of the same type. static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { if (!LHS.getDecl() || !RHS.getDecl()) return !LHS.getDecl() && !RHS.getDecl(); if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) return false; return LHS.Path == RHS.Path; } } static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, const Expr *E, bool AllowNonLiteralTypes = false); static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info, bool InvalidBaseOK = false); static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info, bool InvalidBaseOK = false); static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, EvalInfo &Info); static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, EvalInfo &Info); static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result, EvalInfo &Info); static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result); /// Evaluate an integer or fixed point expression into an APResult. static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result, EvalInfo &Info); /// Evaluate only a fixed point expression into an APResult. static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result, EvalInfo &Info); //===----------------------------------------------------------------------===// // Misc utilities //===----------------------------------------------------------------------===// /// A helper function to create a temporary and set an LValue. template static APValue &createTemporary(const KeyTy *Key, bool IsLifetimeExtended, LValue &LV, CallStackFrame &Frame) { LV.set({Key, Frame.Info.CurrentCall->Index, Frame.Info.CurrentCall->getTempVersion()}); return Frame.createTemporary(Key, IsLifetimeExtended); } /// Negate an APSInt in place, converting it to a signed form if necessary, and /// preserving its value (by extending by up to one bit as needed). static void negateAsSigned(APSInt &Int) { if (Int.isUnsigned() || Int.isMinSignedValue()) { Int = Int.extend(Int.getBitWidth() + 1); Int.setIsSigned(true); } Int = -Int; } /// Produce a string describing the given constexpr call. static void describeCall(CallStackFrame *Frame, raw_ostream &Out) { unsigned ArgIndex = 0; bool IsMemberCall = isa(Frame->Callee) && !isa(Frame->Callee) && cast(Frame->Callee)->isInstance(); if (!IsMemberCall) Out << *Frame->Callee << '('; if (Frame->This && IsMemberCall) { APValue Val; Frame->This->moveInto(Val); Val.printPretty(Out, Frame->Info.Ctx, Frame->This->Designator.MostDerivedType); // FIXME: Add parens around Val if needed. Out << "->" << *Frame->Callee << '('; IsMemberCall = false; } for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(), E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) { if (ArgIndex > (unsigned)IsMemberCall) Out << ", "; const ParmVarDecl *Param = *I; const APValue &Arg = Frame->Arguments[ArgIndex]; Arg.printPretty(Out, Frame->Info.Ctx, Param->getType()); if (ArgIndex == 0 && IsMemberCall) Out << "->" << *Frame->Callee << '('; } Out << ')'; } /// Evaluate an expression to see if it had side-effects, and discard its /// result. /// \return \c true if the caller should keep evaluating. static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) { APValue Scratch; if (!Evaluate(Scratch, Info, E)) // We don't need the value, but we might have skipped a side effect here. return Info.noteSideEffect(); return true; } /// Should this call expression be treated as a string literal? static bool IsStringLiteralCall(const CallExpr *E) { unsigned Builtin = E->getBuiltinCallee(); return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || Builtin == Builtin::BI__builtin___NSStringMakeConstantString); } static bool IsGlobalLValue(APValue::LValueBase B) { // C++11 [expr.const]p3 An address constant expression is a prvalue core // constant expression of pointer type that evaluates to... // ... a null pointer value, or a prvalue core constant expression of type // std::nullptr_t. if (!B) return true; if (const ValueDecl *D = B.dyn_cast()) { // ... the address of an object with static storage duration, if (const VarDecl *VD = dyn_cast(D)) return VD->hasGlobalStorage(); // ... the address of a function, return isa(D); } if (B.is()) return true; const Expr *E = B.get(); switch (E->getStmtClass()) { default: return false; case Expr::CompoundLiteralExprClass: { const CompoundLiteralExpr *CLE = cast(E); return CLE->isFileScope() && CLE->isLValue(); } case Expr::MaterializeTemporaryExprClass: // A materialized temporary might have been lifetime-extended to static // storage duration. return cast(E)->getStorageDuration() == SD_Static; // A string literal has static storage duration. case Expr::StringLiteralClass: case Expr::PredefinedExprClass: case Expr::ObjCStringLiteralClass: case Expr::ObjCEncodeExprClass: case Expr::CXXUuidofExprClass: return true; case Expr::ObjCBoxedExprClass: return cast(E)->isExpressibleAsConstantInitializer(); case Expr::CallExprClass: return IsStringLiteralCall(cast(E)); // For GCC compatibility, &&label has static storage duration. case Expr::AddrLabelExprClass: return true; // A Block literal expression may be used as the initialization value for // Block variables at global or local static scope. case Expr::BlockExprClass: return !cast(E)->getBlockDecl()->hasCaptures(); case Expr::ImplicitValueInitExprClass: // FIXME: // We can never form an lvalue with an implicit value initialization as its // base through expression evaluation, so these only appear in one case: the // implicit variable declaration we invent when checking whether a constexpr // constructor can produce a constant expression. We must assume that such // an expression might be a global lvalue. return true; } } static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { return LVal.Base.dyn_cast(); } static bool IsLiteralLValue(const LValue &Value) { if (Value.getLValueCallIndex()) return false; const Expr *E = Value.Base.dyn_cast(); return E && !isa(E); } static bool IsWeakLValue(const LValue &Value) { const ValueDecl *Decl = GetLValueBaseDecl(Value); return Decl && Decl->isWeak(); } static bool isZeroSized(const LValue &Value) { const ValueDecl *Decl = GetLValueBaseDecl(Value); if (Decl && isa(Decl)) { QualType Ty = Decl->getType(); if (Ty->isArrayType()) return Ty->isIncompleteType() || Decl->getASTContext().getTypeSize(Ty) == 0; } return false; } static bool HasSameBase(const LValue &A, const LValue &B) { if (!A.getLValueBase()) return !B.getLValueBase(); if (!B.getLValueBase()) return false; if (A.getLValueBase().getOpaqueValue() != B.getLValueBase().getOpaqueValue()) { const Decl *ADecl = GetLValueBaseDecl(A); if (!ADecl) return false; const Decl *BDecl = GetLValueBaseDecl(B); if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl()) return false; } return IsGlobalLValue(A.getLValueBase()) || (A.getLValueCallIndex() == B.getLValueCallIndex() && A.getLValueVersion() == B.getLValueVersion()); } static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { assert(Base && "no location for a null lvalue"); const ValueDecl *VD = Base.dyn_cast(); if (VD) Info.Note(VD->getLocation(), diag::note_declared_at); else if (const Expr *E = Base.dyn_cast()) Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here); // We have no information to show for a typeid(T) object. } /// Check that this reference or pointer core constant expression is a valid /// value for an address or reference constant expression. Return true if we /// can fold this expression, whether or not it's a constant expression. static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, QualType Type, const LValue &LVal, Expr::ConstExprUsage Usage) { bool IsReferenceType = Type->isReferenceType(); APValue::LValueBase Base = LVal.getLValueBase(); const SubobjectDesignator &Designator = LVal.getLValueDesignator(); // Check that the object is a global. Note that the fake 'this' object we // manufacture when checking potential constant expressions is conservatively // assumed to be global here. if (!IsGlobalLValue(Base)) { if (Info.getLangOpts().CPlusPlus11) { const ValueDecl *VD = Base.dyn_cast(); Info.FFDiag(Loc, diag::note_constexpr_non_global, 1) << IsReferenceType << !Designator.Entries.empty() << !!VD << VD; NoteLValueLocation(Info, Base); } else { Info.FFDiag(Loc); } // Don't allow references to temporaries to escape. return false; } assert((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"); if (const ValueDecl *VD = Base.dyn_cast()) { if (const VarDecl *Var = dyn_cast(VD)) { // Check if this is a thread-local variable. if (Var->getTLSKind()) return false; // A dllimport variable never acts like a constant. if (Usage == Expr::EvaluateForCodeGen && Var->hasAttr()) return false; } if (const auto *FD = dyn_cast(VD)) { // __declspec(dllimport) must be handled very carefully: // We must never initialize an expression with the thunk in C++. // Doing otherwise would allow the same id-expression to yield // different addresses for the same function in different translation // units. However, this means that we must dynamically initialize the // expression with the contents of the import address table at runtime. // // The C language has no notion of ODR; furthermore, it has no notion of // dynamic initialization. This means that we are permitted to // perform initialization with the address of the thunk. if (Info.getLangOpts().CPlusPlus && Usage == Expr::EvaluateForCodeGen && FD->hasAttr()) return false; } } // Allow address constant expressions to be past-the-end pointers. This is // an extension: the standard requires them to point to an object. if (!IsReferenceType) return true; // A reference constant expression must refer to an object. if (!Base) { // FIXME: diagnostic Info.CCEDiag(Loc); return true; } // Does this refer one past the end of some object? if (!Designator.Invalid && Designator.isOnePastTheEnd()) { const ValueDecl *VD = Base.dyn_cast(); Info.FFDiag(Loc, diag::note_constexpr_past_end, 1) << !Designator.Entries.empty() << !!VD << VD; NoteLValueLocation(Info, Base); } return true; } /// Member pointers are constant expressions unless they point to a /// non-virtual dllimport member function. static bool CheckMemberPointerConstantExpression(EvalInfo &Info, SourceLocation Loc, QualType Type, const APValue &Value, Expr::ConstExprUsage Usage) { const ValueDecl *Member = Value.getMemberPointerDecl(); const auto *FD = dyn_cast_or_null(Member); if (!FD) return true; return Usage == Expr::EvaluateForMangling || FD->isVirtual() || !FD->hasAttr(); } /// Check that this core constant expression is of literal type, and if not, /// produce an appropriate diagnostic. static bool CheckLiteralType(EvalInfo &Info, const Expr *E, const LValue *This = nullptr) { if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx)) return true; // C++1y: A constant initializer for an object o [...] may also invoke // constexpr constructors for o and its subobjects even if those objects // are of non-literal class types. // // C++11 missed this detail for aggregates, so classes like this: // struct foo_t { union { int i; volatile int j; } u; }; // are not (obviously) initializable like so: // __attribute__((__require_constant_initialization__)) // static const foo_t x = {{0}}; // because "i" is a subobject with non-literal initialization (due to the // volatile member of the union). See: // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677 // Therefore, we use the C++1y behavior. if (This && Info.EvaluatingDecl == This->getLValueBase()) return true; // Prvalue constant expressions must be of literal types. if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType(); else Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } /// Check that this core constant expression value is a valid value for a /// constant expression. If not, report an appropriate diagnostic. Does not /// check that the expression is of literal type. static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, QualType Type, const APValue &Value, Expr::ConstExprUsage Usage = Expr::EvaluateForCodeGen, SourceLocation SubobjectLoc = SourceLocation()) { if (!Value.hasValue()) { Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized) << true << Type; if (SubobjectLoc.isValid()) Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here); return false; } // We allow _Atomic(T) to be initialized from anything that T can be // initialized from. if (const AtomicType *AT = Type->getAs()) Type = AT->getValueType(); // Core issue 1454: For a literal constant expression of array or class type, // each subobject of its value shall have been initialized by a constant // expression. if (Value.isArray()) { QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { if (!CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayInitializedElt(I), Usage, SubobjectLoc)) return false; } if (!Value.hasArrayFiller()) return true; return CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayFiller(), Usage, SubobjectLoc); } if (Value.isUnion() && Value.getUnionField()) { return CheckConstantExpression(Info, DiagLoc, Value.getUnionField()->getType(), Value.getUnionValue(), Usage, Value.getUnionField()->getLocation()); } if (Value.isStruct()) { RecordDecl *RD = Type->castAs()->getDecl(); if (const CXXRecordDecl *CD = dyn_cast(RD)) { unsigned BaseIndex = 0; for (const CXXBaseSpecifier &BS : CD->bases()) { if (!CheckConstantExpression(Info, DiagLoc, BS.getType(), Value.getStructBase(BaseIndex), Usage, BS.getBeginLoc())) return false; ++BaseIndex; } } for (const auto *I : RD->fields()) { if (I->isUnnamedBitfield()) continue; if (!CheckConstantExpression(Info, DiagLoc, I->getType(), Value.getStructField(I->getFieldIndex()), Usage, I->getLocation())) return false; } } if (Value.isLValue()) { LValue LVal; LVal.setFrom(Info.Ctx, Value); return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Usage); } if (Value.isMemberPointer()) return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Usage); // Everything else is fine. return true; } static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { // A null base expression indicates a null pointer. These are always // evaluatable, and they are false unless the offset is zero. if (!Value.getLValueBase()) { Result = !Value.getLValueOffset().isZero(); return true; } // We have a non-null base. These are generally known to be true, but if it's // a weak declaration it can be null at runtime. Result = true; const ValueDecl *Decl = Value.getLValueBase().dyn_cast(); return !Decl || !Decl->isWeak(); } static bool HandleConversionToBool(const APValue &Val, bool &Result) { switch (Val.getKind()) { case APValue::None: case APValue::Indeterminate: return false; case APValue::Int: Result = Val.getInt().getBoolValue(); return true; case APValue::FixedPoint: Result = Val.getFixedPoint().getBoolValue(); return true; case APValue::Float: Result = !Val.getFloat().isZero(); return true; case APValue::ComplexInt: Result = Val.getComplexIntReal().getBoolValue() || Val.getComplexIntImag().getBoolValue(); return true; case APValue::ComplexFloat: Result = !Val.getComplexFloatReal().isZero() || !Val.getComplexFloatImag().isZero(); return true; case APValue::LValue: return EvalPointerValueAsBool(Val, Result); case APValue::MemberPointer: Result = Val.getMemberPointerDecl(); return true; case APValue::Vector: case APValue::Array: case APValue::Struct: case APValue::Union: case APValue::AddrLabelDiff: return false; } llvm_unreachable("unknown APValue kind"); } static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, EvalInfo &Info) { assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"); APValue Val; if (!Evaluate(Val, Info, E)) return false; return HandleConversionToBool(Val, Result); } template static bool HandleOverflow(EvalInfo &Info, const Expr *E, const T &SrcValue, QualType DestType) { Info.CCEDiag(E, diag::note_constexpr_overflow) << SrcValue << DestType; return Info.noteUndefinedBehavior(); } static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, QualType SrcType, const APFloat &Value, QualType DestType, APSInt &Result) { unsigned DestWidth = Info.Ctx.getIntWidth(DestType); // Determine whether we are converting to unsigned or signed. bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); Result = APSInt(DestWidth, !DestSigned); bool ignored; if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) & APFloat::opInvalidOp) return HandleOverflow(Info, E, Value, DestType); return true; } static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, QualType SrcType, QualType DestType, APFloat &Result) { APFloat Value = Result; bool ignored; Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), APFloat::rmNearestTiesToEven, &ignored); return true; } static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, QualType DestType, QualType SrcType, const APSInt &Value) { unsigned DestWidth = Info.Ctx.getIntWidth(DestType); // Figure out if this is a truncate, extend or noop cast. // If the input is signed, do a sign extend, noop, or truncate. APSInt Result = Value.extOrTrunc(DestWidth); Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); if (DestType->isBooleanType()) Result = Value.getBoolValue(); return Result; } static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, QualType SrcType, const APSInt &Value, QualType DestType, APFloat &Result) { Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); Result.convertFromAPInt(Value, Value.isSigned(), APFloat::rmNearestTiesToEven); return true; } static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E, APValue &Value, const FieldDecl *FD) { assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield"); if (!Value.isInt()) { // Trying to store a pointer-cast-to-integer into a bitfield. // FIXME: In this case, we should provide the diagnostic for casting // a pointer to an integer. assert(Value.isLValue() && "integral value neither int nor lvalue?"); Info.FFDiag(E); return false; } APSInt &Int = Value.getInt(); unsigned OldBitWidth = Int.getBitWidth(); unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx); if (NewBitWidth < OldBitWidth) Int = Int.trunc(NewBitWidth).extend(OldBitWidth); return true; } static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, llvm::APInt &Res) { APValue SVal; if (!Evaluate(SVal, Info, E)) return false; if (SVal.isInt()) { Res = SVal.getInt(); return true; } if (SVal.isFloat()) { Res = SVal.getFloat().bitcastToAPInt(); return true; } if (SVal.isVector()) { QualType VecTy = E->getType(); unsigned VecSize = Info.Ctx.getTypeSize(VecTy); QualType EltTy = VecTy->castAs()->getElementType(); unsigned EltSize = Info.Ctx.getTypeSize(EltTy); bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); Res = llvm::APInt::getNullValue(VecSize); for (unsigned i = 0; i < SVal.getVectorLength(); i++) { APValue &Elt = SVal.getVectorElt(i); llvm::APInt EltAsInt; if (Elt.isInt()) { EltAsInt = Elt.getInt(); } else if (Elt.isFloat()) { EltAsInt = Elt.getFloat().bitcastToAPInt(); } else { // Don't try to handle vectors of anything other than int or float // (not sure if it's possible to hit this case). Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } unsigned BaseEltSize = EltAsInt.getBitWidth(); if (BigEndian) Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); else Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); } return true; } // Give up if the input isn't an int, float, or vector. For example, we // reject "(v4i16)(intptr_t)&a". Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } /// Perform the given integer operation, which is known to need at most BitWidth /// bits, and check for overflow in the original type (if that type was not an /// unsigned type). template static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E, const APSInt &LHS, const APSInt &RHS, unsigned BitWidth, Operation Op, APSInt &Result) { if (LHS.isUnsigned()) { Result = Op(LHS, RHS); return true; } APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); Result = Value.trunc(LHS.getBitWidth()); if (Result.extend(BitWidth) != Value) { if (Info.checkingForUndefinedBehavior()) Info.Ctx.getDiagnostics().Report(E->getExprLoc(), diag::warn_integer_constant_overflow) << Result.toString(10) << E->getType(); else return HandleOverflow(Info, E, Value, E->getType()); } return true; } /// Perform the given binary integer operation. static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS, BinaryOperatorKind Opcode, APSInt RHS, APSInt &Result) { switch (Opcode) { default: Info.FFDiag(E); return false; case BO_Mul: return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, std::multiplies(), Result); case BO_Add: return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, std::plus(), Result); case BO_Sub: return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, std::minus(), Result); case BO_And: Result = LHS & RHS; return true; case BO_Xor: Result = LHS ^ RHS; return true; case BO_Or: Result = LHS | RHS; return true; case BO_Div: case BO_Rem: if (RHS == 0) { Info.FFDiag(E, diag::note_expr_divide_by_zero); return false; } Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports // this operation and gives the two's complement result. if (RHS.isNegative() && RHS.isAllOnesValue() && LHS.isSigned() && LHS.isMinSignedValue()) return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType()); return true; case BO_Shl: { if (Info.getLangOpts().OpenCL) // OpenCL 6.3j: shift values are effectively % word size of LHS. RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), static_cast(LHS.getBitWidth() - 1)), RHS.isUnsigned()); else if (RHS.isSigned() && RHS.isNegative()) { // During constant-folding, a negative shift is an opposite shift. Such // a shift is not a constant expression. Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; RHS = -RHS; goto shift_right; } shift_left: // C++11 [expr.shift]p1: Shift width must be less than the bit width of // the shifted type. unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); if (SA != RHS) { Info.CCEDiag(E, diag::note_constexpr_large_shift) << RHS << E->getType() << LHS.getBitWidth(); } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus2a) { // C++11 [expr.shift]p2: A signed left shift must have a non-negative // operand, and must not overflow the corresponding unsigned type. // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to // E1 x 2^E2 module 2^N. if (LHS.isNegative()) Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; else if (LHS.countLeadingZeros() < SA) Info.CCEDiag(E, diag::note_constexpr_lshift_discards); } Result = LHS << SA; return true; } case BO_Shr: { if (Info.getLangOpts().OpenCL) // OpenCL 6.3j: shift values are effectively % word size of LHS. RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), static_cast(LHS.getBitWidth() - 1)), RHS.isUnsigned()); else if (RHS.isSigned() && RHS.isNegative()) { // During constant-folding, a negative shift is an opposite shift. Such a // shift is not a constant expression. Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; RHS = -RHS; goto shift_left; } shift_right: // C++11 [expr.shift]p1: Shift width must be less than the bit width of the // shifted type. unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); if (SA != RHS) Info.CCEDiag(E, diag::note_constexpr_large_shift) << RHS << E->getType() << LHS.getBitWidth(); Result = LHS >> SA; return true; } case BO_LT: Result = LHS < RHS; return true; case BO_GT: Result = LHS > RHS; return true; case BO_LE: Result = LHS <= RHS; return true; case BO_GE: Result = LHS >= RHS; return true; case BO_EQ: Result = LHS == RHS; return true; case BO_NE: Result = LHS != RHS; return true; case BO_Cmp: llvm_unreachable("BO_Cmp should be handled elsewhere"); } } /// Perform the given binary floating-point operation, in-place, on LHS. static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E, APFloat &LHS, BinaryOperatorKind Opcode, const APFloat &RHS) { switch (Opcode) { default: Info.FFDiag(E); return false; case BO_Mul: LHS.multiply(RHS, APFloat::rmNearestTiesToEven); break; case BO_Add: LHS.add(RHS, APFloat::rmNearestTiesToEven); break; case BO_Sub: LHS.subtract(RHS, APFloat::rmNearestTiesToEven); break; case BO_Div: // [expr.mul]p4: // If the second operand of / or % is zero the behavior is undefined. if (RHS.isZero()) Info.CCEDiag(E, diag::note_expr_divide_by_zero); LHS.divide(RHS, APFloat::rmNearestTiesToEven); break; } // [expr.pre]p4: // If during the evaluation of an expression, the result is not // mathematically defined [...], the behavior is undefined. // FIXME: C++ rules require us to not conform to IEEE 754 here. if (LHS.isNaN()) { Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); return Info.noteUndefinedBehavior(); } return true; } /// Cast an lvalue referring to a base subobject to a derived class, by /// truncating the lvalue's path to the given length. static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, const RecordDecl *TruncatedType, unsigned TruncatedElements) { SubobjectDesignator &D = Result.Designator; // Check we actually point to a derived class object. if (TruncatedElements == D.Entries.size()) return true; assert(TruncatedElements >= D.MostDerivedPathLength && "not casting to a derived class"); if (!Result.checkSubobject(Info, E, CSK_Derived)) return false; // Truncate the path to the subobject, and remove any derived-to-base offsets. const RecordDecl *RD = TruncatedType; for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); if (isVirtualBaseClass(D.Entries[I])) Result.Offset -= Layout.getVBaseClassOffset(Base); else Result.Offset -= Layout.getBaseClassOffset(Base); RD = Base; } D.Entries.resize(TruncatedElements); return true; } static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, const CXXRecordDecl *Derived, const CXXRecordDecl *Base, const ASTRecordLayout *RL = nullptr) { if (!RL) { if (Derived->isInvalidDecl()) return false; RL = &Info.Ctx.getASTRecordLayout(Derived); } Obj.getLValueOffset() += RL->getBaseClassOffset(Base); Obj.addDecl(Info, E, Base, /*Virtual*/ false); return true; } static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, const CXXRecordDecl *DerivedDecl, const CXXBaseSpecifier *Base) { const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); if (!Base->isVirtual()) return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); SubobjectDesignator &D = Obj.Designator; if (D.Invalid) return false; // Extract most-derived object and corresponding type. DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) return false; // Find the virtual base class. if (DerivedDecl->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); return true; } static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E, QualType Type, LValue &Result) { for (CastExpr::path_const_iterator PathI = E->path_begin(), PathE = E->path_end(); PathI != PathE; ++PathI) { if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), *PathI)) return false; Type = (*PathI)->getType(); } return true; } /// Cast an lvalue referring to a derived class to a known base subobject. static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result, const CXXRecordDecl *DerivedRD, const CXXRecordDecl *BaseRD) { CXXBasePaths Paths(/*FindAmbiguities=*/false, /*RecordPaths=*/true, /*DetectVirtual=*/false); if (!DerivedRD->isDerivedFrom(BaseRD, Paths)) llvm_unreachable("Class must be derived from the passed in base class!"); for (CXXBasePathElement &Elem : Paths.front()) if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base)) return false; return true; } /// Update LVal to refer to the given field, which must be a member of the type /// currently described by LVal. static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, const FieldDecl *FD, const ASTRecordLayout *RL = nullptr) { if (!RL) { if (FD->getParent()->isInvalidDecl()) return false; RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); } unsigned I = FD->getFieldIndex(); LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I))); LVal.addDecl(Info, E, FD); return true; } /// Update LVal to refer to the given indirect field. static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, LValue &LVal, const IndirectFieldDecl *IFD) { for (const auto *C : IFD->chain()) if (!HandleLValueMember(Info, E, LVal, cast(C))) return false; return true; } /// Get the size of the given type in char units. static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, QualType Type, CharUnits &Size) { // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc // extension. if (Type->isVoidType() || Type->isFunctionType()) { Size = CharUnits::One(); return true; } if (Type->isDependentType()) { Info.FFDiag(Loc); return false; } if (!Type->isConstantSizeType()) { // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. // FIXME: Better diagnostic. Info.FFDiag(Loc); return false; } Size = Info.Ctx.getTypeSizeInChars(Type); return true; } /// Update a pointer value to model pointer arithmetic. /// \param Info - Information about the ongoing evaluation. /// \param E - The expression being evaluated, for diagnostic purposes. /// \param LVal - The pointer value to be updated. /// \param EltTy - The pointee type represented by LVal. /// \param Adjustment - The adjustment, in objects of type EltTy, to add. static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, LValue &LVal, QualType EltTy, APSInt Adjustment) { CharUnits SizeOfPointee; if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) return false; LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee); return true; } static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, LValue &LVal, QualType EltTy, int64_t Adjustment) { return HandleLValueArrayAdjustment(Info, E, LVal, EltTy, APSInt::get(Adjustment)); } /// Update an lvalue to refer to a component of a complex number. /// \param Info - Information about the ongoing evaluation. /// \param LVal - The lvalue to be updated. /// \param EltTy - The complex number's component type. /// \param Imag - False for the real component, true for the imaginary. static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, LValue &LVal, QualType EltTy, bool Imag) { if (Imag) { CharUnits SizeOfComponent; if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) return false; LVal.Offset += SizeOfComponent; } LVal.addComplex(Info, E, EltTy, Imag); return true; } /// Try to evaluate the initializer for a variable declaration. /// /// \param Info Information about the ongoing evaluation. /// \param E An expression to be used when printing diagnostics. /// \param VD The variable whose initializer should be obtained. /// \param Frame The frame in which the variable was created. Must be null /// if this variable is not local to the evaluation. /// \param Result Filled in with a pointer to the value of the variable. static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, const VarDecl *VD, CallStackFrame *Frame, APValue *&Result, const LValue *LVal) { // If this is a parameter to an active constexpr function call, perform // argument substitution. if (const ParmVarDecl *PVD = dyn_cast(VD)) { // Assume arguments of a potential constant expression are unknown // constant expressions. if (Info.checkingPotentialConstantExpression()) return false; if (!Frame || !Frame->Arguments) { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } Result = &Frame->Arguments[PVD->getFunctionScopeIndex()]; return true; } // If this is a local variable, dig out its value. if (Frame) { Result = LVal ? Frame->getTemporary(VD, LVal->getLValueVersion()) : Frame->getCurrentTemporary(VD); if (!Result) { // Assume variables referenced within a lambda's call operator that were // not declared within the call operator are captures and during checking // of a potential constant expression, assume they are unknown constant // expressions. assert(isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"); if (Info.checkingPotentialConstantExpression()) return false; // FIXME: implement capture evaluation during constant expr evaluation. Info.FFDiag(E->getBeginLoc(), diag::note_unimplemented_constexpr_lambda_feature_ast) << "captures not currently allowed"; return false; } return true; } // Dig out the initializer, and use the declaration which it's attached to. const Expr *Init = VD->getAnyInitializer(VD); if (!Init || Init->isValueDependent()) { // If we're checking a potential constant expression, the variable could be // initialized later. if (!Info.checkingPotentialConstantExpression()) Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } // If we're currently evaluating the initializer of this declaration, use that // in-flight value. if (Info.EvaluatingDecl.dyn_cast() == VD) { Result = Info.EvaluatingDeclValue; return true; } // Never evaluate the initializer of a weak variable. We can't be sure that // this is the definition which will be used. if (VD->isWeak()) { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } // Check that we can fold the initializer. In C++, we will have already done // this in the cases where it matters for conformance. SmallVector Notes; if (!VD->evaluateValue(Notes)) { Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, Notes.size() + 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); Info.addNotes(Notes); return false; } else if (!VD->checkInitIsICE()) { Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, Notes.size() + 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); Info.addNotes(Notes); } Result = VD->getEvaluatedValue(); return true; } static bool IsConstNonVolatile(QualType T) { Qualifiers Quals = T.getQualifiers(); return Quals.hasConst() && !Quals.hasVolatile(); } /// Get the base index of the given base class within an APValue representing /// the given derived class. static unsigned getBaseIndex(const CXXRecordDecl *Derived, const CXXRecordDecl *Base) { Base = Base->getCanonicalDecl(); unsigned Index = 0; for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), E = Derived->bases_end(); I != E; ++I, ++Index) { if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) return Index; } llvm_unreachable("base class missing from derived class's bases list"); } /// Extract the value of a character from a string literal. static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, uint64_t Index) { assert(!isa(Lit) && "SourceLocExpr should have already been converted to a StringLiteral"); // FIXME: Support MakeStringConstant if (const auto *ObjCEnc = dyn_cast(Lit)) { std::string Str; Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str); assert(Index <= Str.size() && "Index too large"); return APSInt::getUnsigned(Str.c_str()[Index]); } if (auto PE = dyn_cast(Lit)) Lit = PE->getFunctionName(); const StringLiteral *S = cast(Lit); const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(S->getType()); assert(CAT && "string literal isn't an array"); QualType CharType = CAT->getElementType(); assert(CharType->isIntegerType() && "unexpected character type"); APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), CharType->isUnsignedIntegerType()); if (Index < S->getLength()) Value = S->getCodeUnit(Index); return Value; } // Expand a string literal into an array of characters. // // FIXME: This is inefficient; we should probably introduce something similar // to the LLVM ConstantDataArray to make this cheaper. static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S, APValue &Result) { const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(S->getType()); assert(CAT && "string literal isn't an array"); QualType CharType = CAT->getElementType(); assert(CharType->isIntegerType() && "unexpected character type"); unsigned Elts = CAT->getSize().getZExtValue(); Result = APValue(APValue::UninitArray(), std::min(S->getLength(), Elts), Elts); APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), CharType->isUnsignedIntegerType()); if (Result.hasArrayFiller()) Result.getArrayFiller() = APValue(Value); for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) { Value = S->getCodeUnit(I); Result.getArrayInitializedElt(I) = APValue(Value); } } // Expand an array so that it has more than Index filled elements. static void expandArray(APValue &Array, unsigned Index) { unsigned Size = Array.getArraySize(); assert(Index < Size); // Always at least double the number of elements for which we store a value. unsigned OldElts = Array.getArrayInitializedElts(); unsigned NewElts = std::max(Index+1, OldElts * 2); NewElts = std::min(Size, std::max(NewElts, 8u)); // Copy the data across. APValue NewValue(APValue::UninitArray(), NewElts, Size); for (unsigned I = 0; I != OldElts; ++I) NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); for (unsigned I = OldElts; I != NewElts; ++I) NewValue.getArrayInitializedElt(I) = Array.getArrayFiller(); if (NewValue.hasArrayFiller()) NewValue.getArrayFiller() = Array.getArrayFiller(); Array.swap(NewValue); } /// Determine whether a type would actually be read by an lvalue-to-rvalue /// conversion. If it's of class type, we may assume that the copy operation /// is trivial. Note that this is never true for a union type with fields /// (because the copy always "reads" the active member) and always true for /// a non-class type. static bool isReadByLvalueToRvalueConversion(QualType T) { CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); if (!RD || (RD->isUnion() && !RD->field_empty())) return true; if (RD->isEmpty()) return false; for (auto *Field : RD->fields()) if (isReadByLvalueToRvalueConversion(Field->getType())) return true; for (auto &BaseSpec : RD->bases()) if (isReadByLvalueToRvalueConversion(BaseSpec.getType())) return true; return false; } /// Diagnose an attempt to read from any unreadable field within the specified /// type, which might be a class type. static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E, QualType T) { CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); if (!RD) return false; if (!RD->hasMutableFields()) return false; for (auto *Field : RD->fields()) { // If we're actually going to read this field in some way, then it can't // be mutable. If we're in a union, then assigning to a mutable field // (even an empty one) can change the active member, so that's not OK. // FIXME: Add core issue number for the union case. if (Field->isMutable() && (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) { Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field; Info.Note(Field->getLocation(), diag::note_declared_at); return true; } if (diagnoseUnreadableFields(Info, E, Field->getType())) return true; } for (auto &BaseSpec : RD->bases()) if (diagnoseUnreadableFields(Info, E, BaseSpec.getType())) return true; // All mutable fields were empty, and thus not actually read. return false; } static bool lifetimeStartedInEvaluation(EvalInfo &Info, APValue::LValueBase Base) { // A temporary we created. if (Base.getCallIndex()) return true; auto *Evaluating = Info.EvaluatingDecl.dyn_cast(); if (!Evaluating) return false; // The variable whose initializer we're evaluating. if (auto *BaseD = Base.dyn_cast()) if (declaresSameEntity(Evaluating, BaseD)) return true; // A temporary lifetime-extended by the variable whose initializer we're // evaluating. if (auto *BaseE = Base.dyn_cast()) if (auto *BaseMTE = dyn_cast(BaseE)) if (declaresSameEntity(BaseMTE->getExtendingDecl(), Evaluating)) return true; return false; } namespace { /// A handle to a complete object (an object that is not a subobject of /// another object). struct CompleteObject { /// The identity of the object. APValue::LValueBase Base; /// The value of the complete object. APValue *Value; /// The type of the complete object. QualType Type; CompleteObject() : Value(nullptr) {} CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type) : Base(Base), Value(Value), Type(Type) {} bool mayReadMutableMembers(EvalInfo &Info) const { // In C++14 onwards, it is permitted to read a mutable member whose // lifetime began within the evaluation. // FIXME: Should we also allow this in C++11? if (!Info.getLangOpts().CPlusPlus14) return false; return lifetimeStartedInEvaluation(Info, Base); } explicit operator bool() const { return !Type.isNull(); } }; } // end anonymous namespace static QualType getSubobjectType(QualType ObjType, QualType SubobjType, bool IsMutable = false) { // C++ [basic.type.qualifier]p1: // - A const object is an object of type const T or a non-mutable subobject // of a const object. if (ObjType.isConstQualified() && !IsMutable) SubobjType.addConst(); // - A volatile object is an object of type const T or a subobject of a // volatile object. if (ObjType.isVolatileQualified()) SubobjType.addVolatile(); return SubobjType; } /// Find the designated sub-object of an rvalue. template typename SubobjectHandler::result_type findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, const SubobjectDesignator &Sub, SubobjectHandler &handler) { if (Sub.Invalid) // A diagnostic will have already been produced. return handler.failed(); if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) { if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, Sub.isOnePastTheEnd() ? diag::note_constexpr_access_past_end : diag::note_constexpr_access_unsized_array) << handler.AccessKind; else Info.FFDiag(E); return handler.failed(); } APValue *O = Obj.Value; QualType ObjType = Obj.Type; const FieldDecl *LastField = nullptr; const FieldDecl *VolatileField = nullptr; // Walk the designator's path to find the subobject. for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { // Reading an indeterminate value is undefined, but assigning over one is OK. if (O->isAbsent() || (O->isIndeterminate() && handler.AccessKind != AK_Assign)) { if (!Info.checkingPotentialConstantExpression()) Info.FFDiag(E, diag::note_constexpr_access_uninit) << handler.AccessKind << O->isIndeterminate(); return handler.failed(); } // C++ [class.ctor]p5: // const and volatile semantics are not applied on an object under // construction. if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) && ObjType->isRecordType() && Info.isEvaluatingConstructor( Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(), Sub.Entries.begin() + I)) != ConstructionPhase::None) { ObjType = Info.Ctx.getCanonicalType(ObjType); ObjType.removeLocalConst(); ObjType.removeLocalVolatile(); } // If this is our last pass, check that the final object type is OK. if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) { // Accesses to volatile objects are prohibited. if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) { if (Info.getLangOpts().CPlusPlus) { int DiagKind; SourceLocation Loc; const NamedDecl *Decl = nullptr; if (VolatileField) { DiagKind = 2; Loc = VolatileField->getLocation(); Decl = VolatileField; } else if (auto *VD = Obj.Base.dyn_cast()) { DiagKind = 1; Loc = VD->getLocation(); Decl = VD; } else { DiagKind = 0; if (auto *E = Obj.Base.dyn_cast()) Loc = E->getExprLoc(); } Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1) << handler.AccessKind << DiagKind << Decl; Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind; } else { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); } return handler.failed(); } // If we are reading an object of class type, there may still be more // things we need to check: if there are any mutable subobjects, we // cannot perform this read. (This only happens when performing a trivial // copy or assignment.) if (ObjType->isRecordType() && handler.AccessKind == AK_Read && !Obj.mayReadMutableMembers(Info) && diagnoseUnreadableFields(Info, E, ObjType)) return handler.failed(); } if (I == N) { if (!handler.found(*O, ObjType)) return false; // If we modified a bit-field, truncate it to the right width. if (isModification(handler.AccessKind) && LastField && LastField->isBitField() && !truncateBitfieldValue(Info, E, *O, LastField)) return false; return true; } LastField = nullptr; if (ObjType->isArrayType()) { // Next subobject is an array element. const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); assert(CAT && "vla in literal type?"); uint64_t Index = Sub.Entries[I].getAsArrayIndex(); if (CAT->getSize().ule(Index)) { // Note, it should not be possible to form a pointer with a valid // designator which points more than one past the end of the array. if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_access_past_end) << handler.AccessKind; else Info.FFDiag(E); return handler.failed(); } ObjType = CAT->getElementType(); if (O->getArrayInitializedElts() > Index) O = &O->getArrayInitializedElt(Index); else if (handler.AccessKind != AK_Read) { expandArray(*O, Index); O = &O->getArrayInitializedElt(Index); } else O = &O->getArrayFiller(); } else if (ObjType->isAnyComplexType()) { // Next subobject is a complex number. uint64_t Index = Sub.Entries[I].getAsArrayIndex(); if (Index > 1) { if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_access_past_end) << handler.AccessKind; else Info.FFDiag(E); return handler.failed(); } ObjType = getSubobjectType( ObjType, ObjType->castAs()->getElementType()); assert(I == N - 1 && "extracting subobject of scalar?"); if (O->isComplexInt()) { return handler.found(Index ? O->getComplexIntImag() : O->getComplexIntReal(), ObjType); } else { assert(O->isComplexFloat()); return handler.found(Index ? O->getComplexFloatImag() : O->getComplexFloatReal(), ObjType); } } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { if (Field->isMutable() && handler.AccessKind == AK_Read && !Obj.mayReadMutableMembers(Info)) { Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field; Info.Note(Field->getLocation(), diag::note_declared_at); return handler.failed(); } // Next subobject is a class, struct or union field. RecordDecl *RD = ObjType->castAs()->getDecl(); if (RD->isUnion()) { const FieldDecl *UnionField = O->getUnionField(); if (!UnionField || UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member) << handler.AccessKind << Field << !UnionField << UnionField; return handler.failed(); } O = &O->getUnionValue(); } else O = &O->getStructField(Field->getFieldIndex()); ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable()); LastField = Field; if (Field->getType().isVolatileQualified()) VolatileField = Field; } else { // Next subobject is a base class. const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); O = &O->getStructBase(getBaseIndex(Derived, Base)); ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base)); } } } namespace { struct ExtractSubobjectHandler { EvalInfo &Info; APValue &Result; static const AccessKinds AccessKind = AK_Read; typedef bool result_type; bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { Result = Subobj; return true; } bool found(APSInt &Value, QualType SubobjType) { Result = APValue(Value); return true; } bool found(APFloat &Value, QualType SubobjType) { Result = APValue(Value); return true; } }; } // end anonymous namespace const AccessKinds ExtractSubobjectHandler::AccessKind; /// Extract the designated sub-object of an rvalue. static bool extractSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, const SubobjectDesignator &Sub, APValue &Result) { ExtractSubobjectHandler Handler = { Info, Result }; return findSubobject(Info, E, Obj, Sub, Handler); } namespace { struct ModifySubobjectHandler { EvalInfo &Info; APValue &NewVal; const Expr *E; typedef bool result_type; static const AccessKinds AccessKind = AK_Assign; bool checkConst(QualType QT) { // Assigning to a const object has undefined behavior. if (QT.isConstQualified()) { Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; return false; } return true; } bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { if (!checkConst(SubobjType)) return false; // We've been given ownership of NewVal, so just swap it in. Subobj.swap(NewVal); return true; } bool found(APSInt &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (!NewVal.isInt()) { // Maybe trying to write a cast pointer value into a complex? Info.FFDiag(E); return false; } Value = NewVal.getInt(); return true; } bool found(APFloat &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; Value = NewVal.getFloat(); return true; } }; } // end anonymous namespace const AccessKinds ModifySubobjectHandler::AccessKind; /// Update the designated sub-object of an rvalue to the given value. static bool modifySubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, const SubobjectDesignator &Sub, APValue &NewVal) { ModifySubobjectHandler Handler = { Info, NewVal, E }; return findSubobject(Info, E, Obj, Sub, Handler); } /// Find the position where two subobject designators diverge, or equivalently /// the length of the common initial subsequence. static unsigned FindDesignatorMismatch(QualType ObjType, const SubobjectDesignator &A, const SubobjectDesignator &B, bool &WasArrayIndex) { unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); for (/**/; I != N; ++I) { if (!ObjType.isNull() && (ObjType->isArrayType() || ObjType->isAnyComplexType())) { // Next subobject is an array element. if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) { WasArrayIndex = true; return I; } if (ObjType->isAnyComplexType()) ObjType = ObjType->castAs()->getElementType(); else ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); } else { if (A.Entries[I].getAsBaseOrMember() != B.Entries[I].getAsBaseOrMember()) { WasArrayIndex = false; return I; } if (const FieldDecl *FD = getAsField(A.Entries[I])) // Next subobject is a field. ObjType = FD->getType(); else // Next subobject is a base class. ObjType = QualType(); } } WasArrayIndex = false; return I; } /// Determine whether the given subobject designators refer to elements of the /// same array object. static bool AreElementsOfSameArray(QualType ObjType, const SubobjectDesignator &A, const SubobjectDesignator &B) { if (A.Entries.size() != B.Entries.size()) return false; bool IsArray = A.MostDerivedIsArrayElement; if (IsArray && A.MostDerivedPathLength != A.Entries.size()) // A is a subobject of the array element. return false; // If A (and B) designates an array element, the last entry will be the array // index. That doesn't have to match. Otherwise, we're in the 'implicit array // of length 1' case, and the entire path must match. bool WasArrayIndex; unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); return CommonLength >= A.Entries.size() - IsArray; } /// Find the complete object to which an LValue refers. static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, AccessKinds AK, const LValue &LVal, QualType LValType) { if (LVal.InvalidBase) { Info.FFDiag(E); return CompleteObject(); } if (!LVal.Base) { Info.FFDiag(E, diag::note_constexpr_access_null) << AK; return CompleteObject(); } CallStackFrame *Frame = nullptr; unsigned Depth = 0; if (LVal.getLValueCallIndex()) { std::tie(Frame, Depth) = Info.getCallFrameAndDepth(LVal.getLValueCallIndex()); if (!Frame) { Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1) << AK << LVal.Base.is(); NoteLValueLocation(Info, LVal.Base); return CompleteObject(); } } bool IsAccess = isFormalAccess(AK); // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type // is not a constant expression (even if the object is non-volatile). We also // apply this rule to C++98, in order to conform to the expected 'volatile' // semantics. if (IsAccess && LValType.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) Info.FFDiag(E, diag::note_constexpr_access_volatile_type) << AK << LValType; else Info.FFDiag(E); return CompleteObject(); } // Compute value storage location and type of base object. APValue *BaseVal = nullptr; QualType BaseType = getType(LVal.Base); if (const ValueDecl *D = LVal.Base.dyn_cast()) { // In C++98, const, non-volatile integers initialized with ICEs are ICEs. // In C++11, constexpr, non-volatile variables initialized with constant // expressions are constant expressions too. Inside constexpr functions, // parameters are constant expressions even if they're non-const. // In C++1y, objects local to a constant expression (those with a Frame) are // both readable and writable inside constant expressions. // In C, such things can also be folded, although they are not ICEs. const VarDecl *VD = dyn_cast(D); if (VD) { if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) VD = VDef; } if (!VD || VD->isInvalidDecl()) { Info.FFDiag(E); return CompleteObject(); } // Unless we're looking at a local variable or argument in a constexpr call, // the variable we're reading must be const. if (!Frame) { if (Info.getLangOpts().CPlusPlus14 && declaresSameEntity( VD, Info.EvaluatingDecl.dyn_cast())) { // OK, we can read and modify an object if we're in the process of // evaluating its initializer, because its lifetime began in this // evaluation. } else if (isModification(AK)) { // All the remaining cases do not permit modification of the object. Info.FFDiag(E, diag::note_constexpr_modify_global); return CompleteObject(); } else if (VD->isConstexpr()) { // OK, we can read this variable. } else if (BaseType->isIntegralOrEnumerationType()) { // In OpenCL if a variable is in constant address space it is a const // value. if (!(BaseType.isConstQualified() || (Info.getLangOpts().OpenCL && BaseType.getAddressSpace() == LangAS::opencl_constant))) { if (!IsAccess) return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); if (Info.getLangOpts().CPlusPlus) { Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.FFDiag(E); } return CompleteObject(); } } else if (!IsAccess) { return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) { // We support folding of const floating-point types, in order to make // static const data members of such types (supported as an extension) // more useful. if (Info.getLangOpts().CPlusPlus11) { Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.CCEDiag(E); } } else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) { Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD; // Keep evaluating to see what we can do. } else { // FIXME: Allow folding of values of any literal type in all languages. if (Info.checkingPotentialConstantExpression() && VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) { // The definition of this variable could be constexpr. We can't // access it right now, but may be able to in future. } else if (Info.getLangOpts().CPlusPlus11) { Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.FFDiag(E); } return CompleteObject(); } } if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal, &LVal)) return CompleteObject(); } else { const Expr *Base = LVal.Base.dyn_cast(); if (!Frame) { if (const MaterializeTemporaryExpr *MTE = dyn_cast_or_null(Base)) { assert(MTE->getStorageDuration() == SD_Static && "should have a frame for a non-global materialized temporary"); // Per C++1y [expr.const]p2: // an lvalue-to-rvalue conversion [is not allowed unless it applies to] // - a [...] glvalue of integral or enumeration type that refers to // a non-volatile const object [...] // [...] // - a [...] glvalue of literal type that refers to a non-volatile // object whose lifetime began within the evaluation of e. // // C++11 misses the 'began within the evaluation of e' check and // instead allows all temporaries, including things like: // int &&r = 1; // int x = ++r; // constexpr int k = r; // Therefore we use the C++14 rules in C++11 too. const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast(); const ValueDecl *ED = MTE->getExtendingDecl(); if (!(BaseType.isConstQualified() && BaseType->isIntegralOrEnumerationType()) && !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) { if (!IsAccess) return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK; Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); return CompleteObject(); } BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false); assert(BaseVal && "got reference to unevaluated temporary"); } else { if (!IsAccess) return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); APValue Val; LVal.moveInto(Val); Info.FFDiag(E, diag::note_constexpr_access_unreadable_object) << AK << Val.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(LValType)); NoteLValueLocation(Info, LVal.Base); return CompleteObject(); } } else { BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion()); assert(BaseVal && "missing value for temporary"); } } // In C++14, we can't safely access any mutable state when we might be // evaluating after an unmodeled side effect. // // FIXME: Not all local state is mutable. Allow local constant subobjects // to be read here (but take care with 'mutable' fields). if ((Frame && Info.getLangOpts().CPlusPlus14 && Info.EvalStatus.HasSideEffects) || (isModification(AK) && Depth < Info.SpeculativeEvaluationDepth)) return CompleteObject(); return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType); } /// Perform an lvalue-to-rvalue conversion on the given glvalue. This /// can also be used for 'lvalue-to-lvalue' conversions for looking up the /// glvalue referred to by an entity of reference type. /// /// \param Info - Information about the ongoing evaluation. /// \param Conv - The expression for which we are performing the conversion. /// Used for diagnostics. /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the /// case of a non-class type). /// \param LVal - The glvalue on which we are attempting to perform this action. /// \param RVal - The produced value will be placed here. static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type, const LValue &LVal, APValue &RVal) { if (LVal.Designator.Invalid) return false; // Check for special cases where there is no existing APValue to look at. const Expr *Base = LVal.Base.dyn_cast(); if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) { if (const CompoundLiteralExpr *CLE = dyn_cast(Base)) { // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the // initializer until now for such expressions. Such an expression can't be // an ICE in C, so this only matters for fold. if (Type.isVolatileQualified()) { Info.FFDiag(Conv); return false; } APValue Lit; if (!Evaluate(Lit, Info, CLE->getInitializer())) return false; CompleteObject LitObj(LVal.Base, &Lit, Base->getType()); return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal); } else if (isa(Base) || isa(Base)) { // Special-case character extraction so we don't have to construct an // APValue for the whole string. assert(LVal.Designator.Entries.size() <= 1 && "Can only read characters from string literals"); if (LVal.Designator.Entries.empty()) { // Fail for now for LValue to RValue conversion of an array. // (This shouldn't show up in C/C++, but it could be triggered by a // weird EvaluateAsRValue call from a tool.) Info.FFDiag(Conv); return false; } if (LVal.Designator.isOnePastTheEnd()) { if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK_Read; else Info.FFDiag(Conv); return false; } uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex(); RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex)); return true; } } CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type); return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal); } /// Perform an assignment of Val to LVal. Takes ownership of Val. static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, QualType LValType, APValue &Val) { if (LVal.Designator.Invalid) return false; if (!Info.getLangOpts().CPlusPlus14) { Info.FFDiag(E); return false; } CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); } namespace { struct CompoundAssignSubobjectHandler { EvalInfo &Info; const Expr *E; QualType PromotedLHSType; BinaryOperatorKind Opcode; const APValue &RHS; static const AccessKinds AccessKind = AK_Assign; typedef bool result_type; bool checkConst(QualType QT) { // Assigning to a const object has undefined behavior. if (QT.isConstQualified()) { Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; return false; } return true; } bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { switch (Subobj.getKind()) { case APValue::Int: return found(Subobj.getInt(), SubobjType); case APValue::Float: return found(Subobj.getFloat(), SubobjType); case APValue::ComplexInt: case APValue::ComplexFloat: // FIXME: Implement complex compound assignment. Info.FFDiag(E); return false; case APValue::LValue: return foundPointer(Subobj, SubobjType); default: // FIXME: can this happen? Info.FFDiag(E); return false; } } bool found(APSInt &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (!SubobjType->isIntegerType()) { // We don't support compound assignment on integer-cast-to-pointer // values. Info.FFDiag(E); return false; } if (RHS.isInt()) { APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value); if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) return false; Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); return true; } else if (RHS.isFloat()) { APFloat FValue(0.0); return HandleIntToFloatCast(Info, E, SubobjType, Value, PromotedLHSType, FValue) && handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) && HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType, Value); } Info.FFDiag(E); return false; } bool found(APFloat &Value, QualType SubobjType) { return checkConst(SubobjType) && HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, Value) && handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); } bool foundPointer(APValue &Subobj, QualType SubobjType) { if (!checkConst(SubobjType)) return false; QualType PointeeType; if (const PointerType *PT = SubobjType->getAs()) PointeeType = PT->getPointeeType(); if (PointeeType.isNull() || !RHS.isInt() || (Opcode != BO_Add && Opcode != BO_Sub)) { Info.FFDiag(E); return false; } APSInt Offset = RHS.getInt(); if (Opcode == BO_Sub) negateAsSigned(Offset); LValue LVal; LVal.setFrom(Info.Ctx, Subobj); if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) return false; LVal.moveInto(Subobj); return true; } }; } // end anonymous namespace const AccessKinds CompoundAssignSubobjectHandler::AccessKind; /// Perform a compound assignment of LVal = RVal. static bool handleCompoundAssignment( EvalInfo &Info, const Expr *E, const LValue &LVal, QualType LValType, QualType PromotedLValType, BinaryOperatorKind Opcode, const APValue &RVal) { if (LVal.Designator.Invalid) return false; if (!Info.getLangOpts().CPlusPlus14) { Info.FFDiag(E); return false; } CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, RVal }; return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); } namespace { struct IncDecSubobjectHandler { EvalInfo &Info; const UnaryOperator *E; AccessKinds AccessKind; APValue *Old; typedef bool result_type; bool checkConst(QualType QT) { // Assigning to a const object has undefined behavior. if (QT.isConstQualified()) { Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; return false; } return true; } bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { // Stash the old value. Also clear Old, so we don't clobber it later // if we're post-incrementing a complex. if (Old) { *Old = Subobj; Old = nullptr; } switch (Subobj.getKind()) { case APValue::Int: return found(Subobj.getInt(), SubobjType); case APValue::Float: return found(Subobj.getFloat(), SubobjType); case APValue::ComplexInt: return found(Subobj.getComplexIntReal(), SubobjType->castAs()->getElementType() .withCVRQualifiers(SubobjType.getCVRQualifiers())); case APValue::ComplexFloat: return found(Subobj.getComplexFloatReal(), SubobjType->castAs()->getElementType() .withCVRQualifiers(SubobjType.getCVRQualifiers())); case APValue::LValue: return foundPointer(Subobj, SubobjType); default: // FIXME: can this happen? Info.FFDiag(E); return false; } } bool found(APSInt &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (!SubobjType->isIntegerType()) { // We don't support increment / decrement on integer-cast-to-pointer // values. Info.FFDiag(E); return false; } if (Old) *Old = APValue(Value); // bool arithmetic promotes to int, and the conversion back to bool // doesn't reduce mod 2^n, so special-case it. if (SubobjType->isBooleanType()) { if (AccessKind == AK_Increment) Value = 1; else Value = !Value; return true; } bool WasNegative = Value.isNegative(); if (AccessKind == AK_Increment) { ++Value; if (!WasNegative && Value.isNegative() && E->canOverflow()) { APSInt ActualValue(Value, /*IsUnsigned*/true); return HandleOverflow(Info, E, ActualValue, SubobjType); } } else { --Value; if (WasNegative && !Value.isNegative() && E->canOverflow()) { unsigned BitWidth = Value.getBitWidth(); APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); ActualValue.setBit(BitWidth); return HandleOverflow(Info, E, ActualValue, SubobjType); } } return true; } bool found(APFloat &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (Old) *Old = APValue(Value); APFloat One(Value.getSemantics(), 1); if (AccessKind == AK_Increment) Value.add(One, APFloat::rmNearestTiesToEven); else Value.subtract(One, APFloat::rmNearestTiesToEven); return true; } bool foundPointer(APValue &Subobj, QualType SubobjType) { if (!checkConst(SubobjType)) return false; QualType PointeeType; if (const PointerType *PT = SubobjType->getAs()) PointeeType = PT->getPointeeType(); else { Info.FFDiag(E); return false; } LValue LVal; LVal.setFrom(Info.Ctx, Subobj); if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, AccessKind == AK_Increment ? 1 : -1)) return false; LVal.moveInto(Subobj); return true; } }; } // end anonymous namespace /// Perform an increment or decrement on LVal. static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, QualType LValType, bool IsIncrement, APValue *Old) { if (LVal.Designator.Invalid) return false; if (!Info.getLangOpts().CPlusPlus14) { Info.FFDiag(E); return false; } AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); IncDecSubobjectHandler Handler = {Info, cast(E), AK, Old}; return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); } /// Build an lvalue for the object argument of a member function call. static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, LValue &This) { if (Object->getType()->isPointerType()) return EvaluatePointer(Object, This, Info); if (Object->isGLValue()) return EvaluateLValue(Object, This, Info); if (Object->getType()->isLiteralType(Info.Ctx)) return EvaluateTemporary(Object, This, Info); Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType(); return false; } /// HandleMemberPointerAccess - Evaluate a member access operation and build an /// lvalue referring to the result. /// /// \param Info - Information about the ongoing evaluation. /// \param LV - An lvalue referring to the base of the member pointer. /// \param RHS - The member pointer expression. /// \param IncludeMember - Specifies whether the member itself is included in /// the resulting LValue subobject designator. This is not possible when /// creating a bound member function. /// \return The field or method declaration to which the member pointer refers, /// or 0 if evaluation fails. static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, QualType LVType, LValue &LV, const Expr *RHS, bool IncludeMember = true) { MemberPtr MemPtr; if (!EvaluateMemberPointer(RHS, MemPtr, Info)) return nullptr; // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to // member value, the behavior is undefined. if (!MemPtr.getDecl()) { // FIXME: Specific diagnostic. Info.FFDiag(RHS); return nullptr; } if (MemPtr.isDerivedMember()) { // This is a member of some derived class. Truncate LV appropriately. // The end of the derived-to-base path for the base object must match the // derived-to-base path for the member pointer. if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > LV.Designator.Entries.size()) { Info.FFDiag(RHS); return nullptr; } unsigned PathLengthToMember = LV.Designator.Entries.size() - MemPtr.Path.size(); for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { const CXXRecordDecl *LVDecl = getAsBaseClass( LV.Designator.Entries[PathLengthToMember + I]); const CXXRecordDecl *MPDecl = MemPtr.Path[I]; if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { Info.FFDiag(RHS); return nullptr; } } // Truncate the lvalue to the appropriate derived class. if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), PathLengthToMember)) return nullptr; } else if (!MemPtr.Path.empty()) { // Extend the LValue path with the member pointer's path. LV.Designator.Entries.reserve(LV.Designator.Entries.size() + MemPtr.Path.size() + IncludeMember); // Walk down to the appropriate base class. if (const PointerType *PT = LVType->getAs()) LVType = PT->getPointeeType(); const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); assert(RD && "member pointer access on non-class-type expression"); // The first class in the path is that of the lvalue. for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) return nullptr; RD = Base; } // Finally cast to the class containing the member. if (!HandleLValueDirectBase(Info, RHS, LV, RD, MemPtr.getContainingRecord())) return nullptr; } // Add the member. Note that we cannot build bound member functions here. if (IncludeMember) { if (const FieldDecl *FD = dyn_cast(MemPtr.getDecl())) { if (!HandleLValueMember(Info, RHS, LV, FD)) return nullptr; } else if (const IndirectFieldDecl *IFD = dyn_cast(MemPtr.getDecl())) { if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) return nullptr; } else { llvm_unreachable("can't construct reference to bound member function"); } } return MemPtr.getDecl(); } static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, const BinaryOperator *BO, LValue &LV, bool IncludeMember = true) { assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { if (Info.noteFailure()) { MemberPtr MemPtr; EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); } return nullptr; } return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, BO->getRHS(), IncludeMember); } /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on /// the provided lvalue, which currently refers to the base object. static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, LValue &Result) { SubobjectDesignator &D = Result.Designator; if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) return false; QualType TargetQT = E->getType(); if (const PointerType *PT = TargetQT->getAs()) TargetQT = PT->getPointeeType(); // Check this cast lands within the final derived-to-base subobject path. if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) << D.MostDerivedType << TargetQT; return false; } // Check the type of the final cast. We don't need to check the path, // since a cast can only be formed if the path is unique. unsigned NewEntriesSize = D.Entries.size() - E->path_size(); const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); const CXXRecordDecl *FinalType; if (NewEntriesSize == D.MostDerivedPathLength) FinalType = D.MostDerivedType->getAsCXXRecordDecl(); else FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) << D.MostDerivedType << TargetQT; return false; } // Truncate the lvalue to the appropriate derived class. return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); } namespace { enum EvalStmtResult { /// Evaluation failed. ESR_Failed, /// Hit a 'return' statement. ESR_Returned, /// Evaluation succeeded. ESR_Succeeded, /// Hit a 'continue' statement. ESR_Continue, /// Hit a 'break' statement. ESR_Break, /// Still scanning for 'case' or 'default' statement. ESR_CaseNotFound }; } static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) { // We don't need to evaluate the initializer for a static local. if (!VD->hasLocalStorage()) return true; LValue Result; APValue &Val = createTemporary(VD, true, Result, *Info.CurrentCall); const Expr *InitE = VD->getInit(); if (!InitE) { Info.FFDiag(VD->getBeginLoc(), diag::note_constexpr_uninitialized) << false << VD->getType(); Val = APValue(); return false; } if (InitE->isValueDependent()) return false; if (!EvaluateInPlace(Val, Info, Result, InitE)) { // Wipe out any partially-computed value, to allow tracking that this // evaluation failed. Val = APValue(); return false; } return true; } static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { bool OK = true; if (const VarDecl *VD = dyn_cast(D)) OK &= EvaluateVarDecl(Info, VD); if (const DecompositionDecl *DD = dyn_cast(D)) for (auto *BD : DD->bindings()) if (auto *VD = BD->getHoldingVar()) OK &= EvaluateDecl(Info, VD); return OK; } /// Evaluate a condition (either a variable declaration or an expression). static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, const Expr *Cond, bool &Result) { FullExpressionRAII Scope(Info); if (CondDecl && !EvaluateDecl(Info, CondDecl)) return false; return EvaluateAsBooleanCondition(Cond, Result, Info); } namespace { /// A location where the result (returned value) of evaluating a /// statement should be stored. struct StmtResult { /// The APValue that should be filled in with the returned value. APValue &Value; /// The location containing the result, if any (used to support RVO). const LValue *Slot; }; struct TempVersionRAII { CallStackFrame &Frame; TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) { Frame.pushTempVersion(); } ~TempVersionRAII() { Frame.popTempVersion(); } }; } static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, const Stmt *S, const SwitchCase *SC = nullptr); /// Evaluate the body of a loop, and translate the result as appropriate. static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info, const Stmt *Body, const SwitchCase *Case = nullptr) { BlockScopeRAII Scope(Info); switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) { case ESR_Break: return ESR_Succeeded; case ESR_Succeeded: case ESR_Continue: return ESR_Continue; case ESR_Failed: case ESR_Returned: case ESR_CaseNotFound: return ESR; } llvm_unreachable("Invalid EvalStmtResult!"); } /// Evaluate a switch statement. static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info, const SwitchStmt *SS) { BlockScopeRAII Scope(Info); // Evaluate the switch condition. APSInt Value; { FullExpressionRAII Scope(Info); if (const Stmt *Init = SS->getInit()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); if (ESR != ESR_Succeeded) return ESR; } if (SS->getConditionVariable() && !EvaluateDecl(Info, SS->getConditionVariable())) return ESR_Failed; if (!EvaluateInteger(SS->getCond(), Value, Info)) return ESR_Failed; } // Find the switch case corresponding to the value of the condition. // FIXME: Cache this lookup. const SwitchCase *Found = nullptr; for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; SC = SC->getNextSwitchCase()) { if (isa(SC)) { Found = SC; continue; } const CaseStmt *CS = cast(SC); APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) : LHS; if (LHS <= Value && Value <= RHS) { Found = SC; break; } } if (!Found) return ESR_Succeeded; // Search the switch body for the switch case and evaluate it from there. switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) { case ESR_Break: return ESR_Succeeded; case ESR_Succeeded: case ESR_Continue: case ESR_Failed: case ESR_Returned: return ESR; case ESR_CaseNotFound: // This can only happen if the switch case is nested within a statement // expression. We have no intention of supporting that. Info.FFDiag(Found->getBeginLoc(), diag::note_constexpr_stmt_expr_unsupported); return ESR_Failed; } llvm_unreachable("Invalid EvalStmtResult!"); } // Evaluate a statement. static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, const Stmt *S, const SwitchCase *Case) { if (!Info.nextStep(S)) return ESR_Failed; // If we're hunting down a 'case' or 'default' label, recurse through // substatements until we hit the label. if (Case) { // FIXME: We don't start the lifetime of objects whose initialization we // jump over. However, such objects must be of class type with a trivial // default constructor that initialize all subobjects, so must be empty, // so this almost never matters. switch (S->getStmtClass()) { case Stmt::CompoundStmtClass: // FIXME: Precompute which substatement of a compound statement we // would jump to, and go straight there rather than performing a // linear scan each time. case Stmt::LabelStmtClass: case Stmt::AttributedStmtClass: case Stmt::DoStmtClass: break; case Stmt::CaseStmtClass: case Stmt::DefaultStmtClass: if (Case == S) Case = nullptr; break; case Stmt::IfStmtClass: { // FIXME: Precompute which side of an 'if' we would jump to, and go // straight there rather than scanning both sides. const IfStmt *IS = cast(S); // Wrap the evaluation in a block scope, in case it's a DeclStmt // preceded by our switch label. BlockScopeRAII Scope(Info); EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); if (ESR != ESR_CaseNotFound || !IS->getElse()) return ESR; return EvaluateStmt(Result, Info, IS->getElse(), Case); } case Stmt::WhileStmtClass: { EvalStmtResult ESR = EvaluateLoopBody(Result, Info, cast(S)->getBody(), Case); if (ESR != ESR_Continue) return ESR; break; } case Stmt::ForStmtClass: { const ForStmt *FS = cast(S); EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody(), Case); if (ESR != ESR_Continue) return ESR; if (FS->getInc()) { FullExpressionRAII IncScope(Info); if (!EvaluateIgnoredValue(Info, FS->getInc())) return ESR_Failed; } break; } case Stmt::DeclStmtClass: // FIXME: If the variable has initialization that can't be jumped over, // bail out of any immediately-surrounding compound-statement too. default: return ESR_CaseNotFound; } } switch (S->getStmtClass()) { default: if (const Expr *E = dyn_cast(S)) { // Don't bother evaluating beyond an expression-statement which couldn't // be evaluated. FullExpressionRAII Scope(Info); if (!EvaluateIgnoredValue(Info, E)) return ESR_Failed; return ESR_Succeeded; } Info.FFDiag(S->getBeginLoc()); return ESR_Failed; case Stmt::NullStmtClass: return ESR_Succeeded; case Stmt::DeclStmtClass: { const DeclStmt *DS = cast(S); for (const auto *DclIt : DS->decls()) { // Each declaration initialization is its own full-expression. // FIXME: This isn't quite right; if we're performing aggregate // initialization, each braced subexpression is its own full-expression. FullExpressionRAII Scope(Info); if (!EvaluateDecl(Info, DclIt) && !Info.noteFailure()) return ESR_Failed; } return ESR_Succeeded; } case Stmt::ReturnStmtClass: { const Expr *RetExpr = cast(S)->getRetValue(); FullExpressionRAII Scope(Info); if (RetExpr && !(Result.Slot ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr) : Evaluate(Result.Value, Info, RetExpr))) return ESR_Failed; return ESR_Returned; } case Stmt::CompoundStmtClass: { BlockScopeRAII Scope(Info); const CompoundStmt *CS = cast(S); for (const auto *BI : CS->body()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case); if (ESR == ESR_Succeeded) Case = nullptr; else if (ESR != ESR_CaseNotFound) return ESR; } return Case ? ESR_CaseNotFound : ESR_Succeeded; } case Stmt::IfStmtClass: { const IfStmt *IS = cast(S); // Evaluate the condition, as either a var decl or as an expression. BlockScopeRAII Scope(Info); if (const Stmt *Init = IS->getInit()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); if (ESR != ESR_Succeeded) return ESR; } bool Cond; if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) return ESR_Failed; if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); if (ESR != ESR_Succeeded) return ESR; } return ESR_Succeeded; } case Stmt::WhileStmtClass: { const WhileStmt *WS = cast(S); while (true) { BlockScopeRAII Scope(Info); bool Continue; if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), Continue)) return ESR_Failed; if (!Continue) break; EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); if (ESR != ESR_Continue) return ESR; } return ESR_Succeeded; } case Stmt::DoStmtClass: { const DoStmt *DS = cast(S); bool Continue; do { EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); if (ESR != ESR_Continue) return ESR; Case = nullptr; FullExpressionRAII CondScope(Info); if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info)) return ESR_Failed; } while (Continue); return ESR_Succeeded; } case Stmt::ForStmtClass: { const ForStmt *FS = cast(S); BlockScopeRAII Scope(Info); if (FS->getInit()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); if (ESR != ESR_Succeeded) return ESR; } while (true) { BlockScopeRAII Scope(Info); bool Continue = true; if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), FS->getCond(), Continue)) return ESR_Failed; if (!Continue) break; EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); if (ESR != ESR_Continue) return ESR; if (FS->getInc()) { FullExpressionRAII IncScope(Info); if (!EvaluateIgnoredValue(Info, FS->getInc())) return ESR_Failed; } } return ESR_Succeeded; } case Stmt::CXXForRangeStmtClass: { const CXXForRangeStmt *FS = cast(S); BlockScopeRAII Scope(Info); // Evaluate the init-statement if present. if (FS->getInit()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); if (ESR != ESR_Succeeded) return ESR; } // Initialize the __range variable. EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); if (ESR != ESR_Succeeded) return ESR; // Create the __begin and __end iterators. ESR = EvaluateStmt(Result, Info, FS->getBeginStmt()); if (ESR != ESR_Succeeded) return ESR; ESR = EvaluateStmt(Result, Info, FS->getEndStmt()); if (ESR != ESR_Succeeded) return ESR; while (true) { // Condition: __begin != __end. { bool Continue = true; FullExpressionRAII CondExpr(Info); if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) return ESR_Failed; if (!Continue) break; } // User's variable declaration, initialized by *__begin. BlockScopeRAII InnerScope(Info); ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); if (ESR != ESR_Succeeded) return ESR; // Loop body. ESR = EvaluateLoopBody(Result, Info, FS->getBody()); if (ESR != ESR_Continue) return ESR; // Increment: ++__begin if (!EvaluateIgnoredValue(Info, FS->getInc())) return ESR_Failed; } return ESR_Succeeded; } case Stmt::SwitchStmtClass: return EvaluateSwitch(Result, Info, cast(S)); case Stmt::ContinueStmtClass: return ESR_Continue; case Stmt::BreakStmtClass: return ESR_Break; case Stmt::LabelStmtClass: return EvaluateStmt(Result, Info, cast(S)->getSubStmt(), Case); case Stmt::AttributedStmtClass: // As a general principle, C++11 attributes can be ignored without // any semantic impact. return EvaluateStmt(Result, Info, cast(S)->getSubStmt(), Case); case Stmt::CaseStmtClass: case Stmt::DefaultStmtClass: return EvaluateStmt(Result, Info, cast(S)->getSubStmt(), Case); case Stmt::CXXTryStmtClass: // Evaluate try blocks by evaluating all sub statements. return EvaluateStmt(Result, Info, cast(S)->getTryBlock(), Case); } } /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial /// default constructor. If so, we'll fold it whether or not it's marked as /// constexpr. If it is marked as constexpr, we will never implicitly define it, /// so we need special handling. static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, const CXXConstructorDecl *CD, bool IsValueInitialization) { if (!CD->isTrivial() || !CD->isDefaultConstructor()) return false; // Value-initialization does not call a trivial default constructor, so such a // call is a core constant expression whether or not the constructor is // constexpr. if (!CD->isConstexpr() && !IsValueInitialization) { if (Info.getLangOpts().CPlusPlus11) { // FIXME: If DiagDecl is an implicitly-declared special member function, // we should be much more explicit about why it's not constexpr. Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; Info.Note(CD->getLocation(), diag::note_declared_at); } else { Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); } } return true; } /// CheckConstexprFunction - Check that a function can be called in a constant /// expression. static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Declaration, const FunctionDecl *Definition, const Stmt *Body) { // Potential constant expressions can contain calls to declared, but not yet // defined, constexpr functions. if (Info.checkingPotentialConstantExpression() && !Definition && Declaration->isConstexpr()) return false; // Bail out if the function declaration itself is invalid. We will // have produced a relevant diagnostic while parsing it, so just // note the problematic sub-expression. if (Declaration->isInvalidDecl()) { Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); return false; } // DR1872: An instantiated virtual constexpr function can't be called in a // constant expression (prior to C++20). We can still constant-fold such a // call. if (!Info.Ctx.getLangOpts().CPlusPlus2a && isa(Declaration) && cast(Declaration)->isVirtual()) Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call); if (Definition && Definition->isInvalidDecl()) { Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); return false; } // Can we evaluate this function call? if (Definition && Definition->isConstexpr() && Body) return true; if (Info.getLangOpts().CPlusPlus11) { const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; // If this function is not constexpr because it is an inherited // non-constexpr constructor, diagnose that directly. auto *CD = dyn_cast(DiagDecl); if (CD && CD->isInheritingConstructor()) { auto *Inherited = CD->getInheritedConstructor().getConstructor(); if (!Inherited->isConstexpr()) DiagDecl = CD = Inherited; } // FIXME: If DiagDecl is an implicitly-declared special member function // or an inheriting constructor, we should be much more explicit about why // it's not constexpr. if (CD && CD->isInheritingConstructor()) Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1) << CD->getInheritedConstructor().getConstructor()->getParent(); else Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1) << DiagDecl->isConstexpr() << (bool)CD << DiagDecl; Info.Note(DiagDecl->getLocation(), diag::note_declared_at); } else { Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); } return false; } namespace { struct CheckDynamicTypeHandler { AccessKinds AccessKind; typedef bool result_type; bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { return true; } bool found(APSInt &Value, QualType SubobjType) { return true; } bool found(APFloat &Value, QualType SubobjType) { return true; } }; } // end anonymous namespace /// Check that we can access the notional vptr of an object / determine its /// dynamic type. static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This, AccessKinds AK, bool Polymorphic) { if (This.Designator.Invalid) return false; CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType()); if (!Obj) return false; if (!Obj.Value) { // The object is not usable in constant expressions, so we can't inspect // its value to see if it's in-lifetime or what the active union members // are. We can still check for a one-past-the-end lvalue. if (This.Designator.isOnePastTheEnd() || This.Designator.isMostDerivedAnUnsizedArray()) { Info.FFDiag(E, This.Designator.isOnePastTheEnd() ? diag::note_constexpr_access_past_end : diag::note_constexpr_access_unsized_array) << AK; return false; } else if (Polymorphic) { // Conservatively refuse to perform a polymorphic operation if we would // not be able to read a notional 'vptr' value. APValue Val; This.moveInto(Val); QualType StarThisType = Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx)); Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type) << AK << Val.getAsString(Info.Ctx, StarThisType); return false; } return true; } CheckDynamicTypeHandler Handler{AK}; return Obj && findSubobject(Info, E, Obj, This.Designator, Handler); } /// Check that the pointee of the 'this' pointer in a member function call is /// either within its lifetime or in its period of construction or destruction. static bool checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E, const LValue &This) { return checkDynamicType(Info, E, This, AK_MemberCall, false); } struct DynamicType { /// The dynamic class type of the object. const CXXRecordDecl *Type; /// The corresponding path length in the lvalue. unsigned PathLength; }; static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator, unsigned PathLength) { assert(PathLength >= Designator.MostDerivedPathLength && PathLength <= Designator.Entries.size() && "invalid path length"); return (PathLength == Designator.MostDerivedPathLength) ? Designator.MostDerivedType->getAsCXXRecordDecl() : getAsBaseClass(Designator.Entries[PathLength - 1]); } /// Determine the dynamic type of an object. static Optional ComputeDynamicType(EvalInfo &Info, const Expr *E, LValue &This, AccessKinds AK) { // If we don't have an lvalue denoting an object of class type, there is no // meaningful dynamic type. (We consider objects of non-class type to have no // dynamic type.) if (!checkDynamicType(Info, E, This, AK, true)) return None; // Refuse to compute a dynamic type in the presence of virtual bases. This // shouldn't happen other than in constant-folding situations, since literal // types can't have virtual bases. // // Note that consumers of DynamicType assume that the type has no virtual // bases, and will need modifications if this restriction is relaxed. const CXXRecordDecl *Class = This.Designator.MostDerivedType->getAsCXXRecordDecl(); if (!Class || Class->getNumVBases()) { Info.FFDiag(E); return None; } // FIXME: For very deep class hierarchies, it might be beneficial to use a // binary search here instead. But the overwhelmingly common case is that // we're not in the middle of a constructor, so it probably doesn't matter // in practice. ArrayRef Path = This.Designator.Entries; for (unsigned PathLength = This.Designator.MostDerivedPathLength; PathLength <= Path.size(); ++PathLength) { switch (Info.isEvaluatingConstructor(This.getLValueBase(), Path.slice(0, PathLength))) { case ConstructionPhase::Bases: // We're constructing a base class. This is not the dynamic type. break; case ConstructionPhase::None: case ConstructionPhase::AfterBases: // We've finished constructing the base classes, so this is the dynamic // type. return DynamicType{getBaseClassType(This.Designator, PathLength), PathLength}; } } // CWG issue 1517: we're constructing a base class of the object described by // 'This', so that object has not yet begun its period of construction and // any polymorphic operation on it results in undefined behavior. Info.FFDiag(E); return None; } /// Perform virtual dispatch. static const CXXMethodDecl *HandleVirtualDispatch( EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found, llvm::SmallVectorImpl &CovariantAdjustmentPath) { Optional DynType = ComputeDynamicType(Info, E, This, AK_MemberCall); if (!DynType) return nullptr; // Find the final overrider. It must be declared in one of the classes on the // path from the dynamic type to the static type. // FIXME: If we ever allow literal types to have virtual base classes, that // won't be true. const CXXMethodDecl *Callee = Found; unsigned PathLength = DynType->PathLength; for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) { const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength); const CXXMethodDecl *Overrider = Found->getCorrespondingMethodDeclaredInClass(Class, false); if (Overrider) { Callee = Overrider; break; } } // C++2a [class.abstract]p6: // the effect of making a virtual call to a pure virtual function [...] is // undefined if (Callee->isPure()) { Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee; Info.Note(Callee->getLocation(), diag::note_declared_at); return nullptr; } // If necessary, walk the rest of the path to determine the sequence of // covariant adjustment steps to apply. if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(), Found->getReturnType())) { CovariantAdjustmentPath.push_back(Callee->getReturnType()); for (unsigned CovariantPathLength = PathLength + 1; CovariantPathLength != This.Designator.Entries.size(); ++CovariantPathLength) { const CXXRecordDecl *NextClass = getBaseClassType(This.Designator, CovariantPathLength); const CXXMethodDecl *Next = Found->getCorrespondingMethodDeclaredInClass(NextClass, false); if (Next && !Info.Ctx.hasSameUnqualifiedType( Next->getReturnType(), CovariantAdjustmentPath.back())) CovariantAdjustmentPath.push_back(Next->getReturnType()); } if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(), CovariantAdjustmentPath.back())) CovariantAdjustmentPath.push_back(Found->getReturnType()); } // Perform 'this' adjustment. if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength)) return nullptr; return Callee; } /// Perform the adjustment from a value returned by a virtual function to /// a value of the statically expected type, which may be a pointer or /// reference to a base class of the returned type. static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E, APValue &Result, ArrayRef Path) { assert(Result.isLValue() && "unexpected kind of APValue for covariant return"); if (Result.isNullPointer()) return true; LValue LVal; LVal.setFrom(Info.Ctx, Result); const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl(); for (unsigned I = 1; I != Path.size(); ++I) { const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl(); assert(OldClass && NewClass && "unexpected kind of covariant return"); if (OldClass != NewClass && !CastToBaseClass(Info, E, LVal, OldClass, NewClass)) return false; OldClass = NewClass; } LVal.moveInto(Result); return true; } /// Determine whether \p Base, which is known to be a direct base class of /// \p Derived, is a public base class. static bool isBaseClassPublic(const CXXRecordDecl *Derived, const CXXRecordDecl *Base) { for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) { auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl(); if (BaseClass && declaresSameEntity(BaseClass, Base)) return BaseSpec.getAccessSpecifier() == AS_public; } llvm_unreachable("Base is not a direct base of Derived"); } /// Apply the given dynamic cast operation on the provided lvalue. /// /// This implements the hard case of dynamic_cast, requiring a "runtime check" /// to find a suitable target subobject. static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E, LValue &Ptr) { // We can't do anything with a non-symbolic pointer value. SubobjectDesignator &D = Ptr.Designator; if (D.Invalid) return false; // C++ [expr.dynamic.cast]p6: // If v is a null pointer value, the result is a null pointer value. if (Ptr.isNullPointer() && !E->isGLValue()) return true; // For all the other cases, we need the pointer to point to an object within // its lifetime / period of construction / destruction, and we need to know // its dynamic type. Optional DynType = ComputeDynamicType(Info, E, Ptr, AK_DynamicCast); if (!DynType) return false; // C++ [expr.dynamic.cast]p7: // If T is "pointer to cv void", then the result is a pointer to the most // derived object if (E->getType()->isVoidPointerType()) return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength); const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl(); assert(C && "dynamic_cast target is not void pointer nor class"); CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C)); auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) { // C++ [expr.dynamic.cast]p9: if (!E->isGLValue()) { // The value of a failed cast to pointer type is the null pointer value // of the required result type. auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType()); Ptr.setNull(E->getType(), TargetVal); return true; } // A failed cast to reference type throws [...] std::bad_cast. unsigned DiagKind; if (!Paths && (declaresSameEntity(DynType->Type, C) || DynType->Type->isDerivedFrom(C))) DiagKind = 0; else if (!Paths || Paths->begin() == Paths->end()) DiagKind = 1; else if (Paths->isAmbiguous(CQT)) DiagKind = 2; else { assert(Paths->front().Access != AS_public && "why did the cast fail?"); DiagKind = 3; } Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed) << DiagKind << Ptr.Designator.getType(Info.Ctx) << Info.Ctx.getRecordType(DynType->Type) << E->getType().getUnqualifiedType(); return false; }; // Runtime check, phase 1: // Walk from the base subobject towards the derived object looking for the // target type. for (int PathLength = Ptr.Designator.Entries.size(); PathLength >= (int)DynType->PathLength; --PathLength) { const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength); if (declaresSameEntity(Class, C)) return CastToDerivedClass(Info, E, Ptr, Class, PathLength); // We can only walk across public inheritance edges. if (PathLength > (int)DynType->PathLength && !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1), Class)) return RuntimeCheckFailed(nullptr); } // Runtime check, phase 2: // Search the dynamic type for an unambiguous public base of type C. CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, /*DetectVirtual=*/false); if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) && Paths.front().Access == AS_public) { // Downcast to the dynamic type... if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength)) return false; // ... then upcast to the chosen base class subobject. for (CXXBasePathElement &Elem : Paths.front()) if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base)) return false; return true; } // Otherwise, the runtime check fails. return RuntimeCheckFailed(&Paths); } namespace { struct StartLifetimeOfUnionMemberHandler { const FieldDecl *Field; static const AccessKinds AccessKind = AK_Assign; APValue getDefaultInitValue(QualType SubobjType) { if (auto *RD = SubobjType->getAsCXXRecordDecl()) { if (RD->isUnion()) return APValue((const FieldDecl*)nullptr); APValue Struct(APValue::UninitStruct(), RD->getNumBases(), std::distance(RD->field_begin(), RD->field_end())); unsigned Index = 0; for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), End = RD->bases_end(); I != End; ++I, ++Index) Struct.getStructBase(Index) = getDefaultInitValue(I->getType()); for (const auto *I : RD->fields()) { if (I->isUnnamedBitfield()) continue; Struct.getStructField(I->getFieldIndex()) = getDefaultInitValue(I->getType()); } return Struct; } if (auto *AT = dyn_cast_or_null( SubobjType->getAsArrayTypeUnsafe())) { APValue Array(APValue::UninitArray(), 0, AT->getSize().getZExtValue()); if (Array.hasArrayFiller()) Array.getArrayFiller() = getDefaultInitValue(AT->getElementType()); return Array; } return APValue::IndeterminateValue(); } typedef bool result_type; bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { // We are supposed to perform no initialization but begin the lifetime of // the object. We interpret that as meaning to do what default // initialization of the object would do if all constructors involved were // trivial: // * All base, non-variant member, and array element subobjects' lifetimes // begin // * No variant members' lifetimes begin // * All scalar subobjects whose lifetimes begin have indeterminate values assert(SubobjType->isUnionType()); if (!declaresSameEntity(Subobj.getUnionField(), Field)) Subobj.setUnion(Field, getDefaultInitValue(Field->getType())); return true; } bool found(APSInt &Value, QualType SubobjType) { llvm_unreachable("wrong value kind for union object"); } bool found(APFloat &Value, QualType SubobjType) { llvm_unreachable("wrong value kind for union object"); } }; } // end anonymous namespace const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind; /// Handle a builtin simple-assignment or a call to a trivial assignment /// operator whose left-hand side might involve a union member access. If it /// does, implicitly start the lifetime of any accessed union elements per /// C++20 [class.union]5. static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr, const LValue &LHS) { if (LHS.InvalidBase || LHS.Designator.Invalid) return false; llvm::SmallVector, 4> UnionPathLengths; // C++ [class.union]p5: // define the set S(E) of subexpressions of E as follows: unsigned PathLength = LHS.Designator.Entries.size(); for (const Expr *E = LHSExpr; E != nullptr;) { // -- If E is of the form A.B, S(E) contains the elements of S(A)... if (auto *ME = dyn_cast(E)) { auto *FD = dyn_cast(ME->getMemberDecl()); if (!FD) break; // ... and also contains A.B if B names a union member if (FD->getParent()->isUnion()) UnionPathLengths.push_back({PathLength - 1, FD}); E = ME->getBase(); --PathLength; assert(declaresSameEntity(FD, LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())); // -- If E is of the form A[B] and is interpreted as a built-in array // subscripting operator, S(E) is [S(the array operand, if any)]. } else if (auto *ASE = dyn_cast(E)) { // Step over an ArrayToPointerDecay implicit cast. auto *Base = ASE->getBase()->IgnoreImplicit(); if (!Base->getType()->isArrayType()) break; E = Base; --PathLength; } else if (auto *ICE = dyn_cast(E)) { // Step over a derived-to-base conversion. E = ICE->getSubExpr(); if (ICE->getCastKind() == CK_NoOp) continue; if (ICE->getCastKind() != CK_DerivedToBase && ICE->getCastKind() != CK_UncheckedDerivedToBase) break; // Walk path backwards as we walk up from the base to the derived class. for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) { --PathLength; (void)Elt; assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())); } // -- Otherwise, S(E) is empty. } else { break; } } // Common case: no unions' lifetimes are started. if (UnionPathLengths.empty()) return true; // if modification of X [would access an inactive union member], an object // of the type of X is implicitly created CompleteObject Obj = findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType()); if (!Obj) return false; for (std::pair LengthAndField : llvm::reverse(UnionPathLengths)) { // Form a designator for the union object. SubobjectDesignator D = LHS.Designator; D.truncate(Info.Ctx, LHS.Base, LengthAndField.first); StartLifetimeOfUnionMemberHandler StartLifetime{LengthAndField.second}; if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime)) return false; } return true; } /// Determine if a class has any fields that might need to be copied by a /// trivial copy or move operation. static bool hasFields(const CXXRecordDecl *RD) { if (!RD || RD->isEmpty()) return false; for (auto *FD : RD->fields()) { if (FD->isUnnamedBitfield()) continue; return true; } for (auto &Base : RD->bases()) if (hasFields(Base.getType()->getAsCXXRecordDecl())) return true; return false; } namespace { typedef SmallVector ArgVector; } /// EvaluateArgs - Evaluate the arguments to a function call. static bool EvaluateArgs(ArrayRef Args, ArgVector &ArgValues, EvalInfo &Info, const FunctionDecl *Callee) { bool Success = true; llvm::SmallBitVector ForbiddenNullArgs; if (Callee->hasAttr()) { ForbiddenNullArgs.resize(Args.size()); for (const auto *Attr : Callee->specific_attrs()) { if (!Attr->args_size()) { ForbiddenNullArgs.set(); break; } else for (auto Idx : Attr->args()) { unsigned ASTIdx = Idx.getASTIndex(); if (ASTIdx >= Args.size()) continue; ForbiddenNullArgs[ASTIdx] = 1; } } } for (ArrayRef::iterator I = Args.begin(), E = Args.end(); I != E; ++I) { if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) { // If we're checking for a potential constant expression, evaluate all // initializers even if some of them fail. if (!Info.noteFailure()) return false; Success = false; } else if (!ForbiddenNullArgs.empty() && ForbiddenNullArgs[I - Args.begin()] && ArgValues[I - Args.begin()].isNullPointer()) { Info.CCEDiag(*I, diag::note_non_null_attribute_failed); if (!Info.noteFailure()) return false; Success = false; } } return Success; } /// Evaluate a function call. static bool HandleFunctionCall(SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, ArrayRef Args, const Stmt *Body, EvalInfo &Info, APValue &Result, const LValue *ResultSlot) { ArgVector ArgValues(Args.size()); if (!EvaluateArgs(Args, ArgValues, Info, Callee)) return false; if (!Info.CheckCallLimit(CallLoc)) return false; CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); // For a trivial copy or move assignment, perform an APValue copy. This is // essential for unions, where the operations performed by the assignment // operator cannot be represented as statements. // // Skip this for non-union classes with no fields; in that case, the defaulted // copy/move does not actually read the object. const CXXMethodDecl *MD = dyn_cast(Callee); if (MD && MD->isDefaulted() && (MD->getParent()->isUnion() || (MD->isTrivial() && hasFields(MD->getParent())))) { assert(This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())); LValue RHS; RHS.setFrom(Info.Ctx, ArgValues[0]); APValue RHSValue; if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), RHS, RHSValue)) return false; if (Info.getLangOpts().CPlusPlus2a && MD->isTrivial() && !HandleUnionActiveMemberChange(Info, Args[0], *This)) return false; if (!handleAssignment(Info, Args[0], *This, MD->getThisType(), RHSValue)) return false; This->moveInto(Result); return true; } else if (MD && isLambdaCallOperator(MD)) { // We're in a lambda; determine the lambda capture field maps unless we're // just constexpr checking a lambda's call operator. constexpr checking is // done before the captures have been added to the closure object (unless // we're inferring constexpr-ness), so we don't have access to them in this // case. But since we don't need the captures to constexpr check, we can // just ignore them. if (!Info.checkingPotentialConstantExpression()) MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields, Frame.LambdaThisCaptureField); } StmtResult Ret = {Result, ResultSlot}; EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body); if (ESR == ESR_Succeeded) { if (Callee->getReturnType()->isVoidType()) return true; Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return); } return ESR == ESR_Returned; } /// Evaluate a constructor call. static bool HandleConstructorCall(const Expr *E, const LValue &This, APValue *ArgValues, const CXXConstructorDecl *Definition, EvalInfo &Info, APValue &Result) { SourceLocation CallLoc = E->getExprLoc(); if (!Info.CheckCallLimit(CallLoc)) return false; const CXXRecordDecl *RD = Definition->getParent(); if (RD->getNumVBases()) { Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD; return false; } EvalInfo::EvaluatingConstructorRAII EvalObj( Info, ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries}, RD->getNumBases()); CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues); // FIXME: Creating an APValue just to hold a nonexistent return value is // wasteful. APValue RetVal; StmtResult Ret = {RetVal, nullptr}; // If it's a delegating constructor, delegate. if (Definition->isDelegatingConstructor()) { CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); { FullExpressionRAII InitScope(Info); if (!EvaluateInPlace(Result, Info, This, (*I)->getInit())) return false; } return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed; } // For a trivial copy or move constructor, perform an APValue copy. This is // essential for unions (or classes with anonymous union members), where the // operations performed by the constructor cannot be represented by // ctor-initializers. // // Skip this for empty non-union classes; we should not perform an // lvalue-to-rvalue conversion on them because their copy constructor does not // actually read them. if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() && (Definition->getParent()->isUnion() || (Definition->isTrivial() && hasFields(Definition->getParent())))) { LValue RHS; RHS.setFrom(Info.Ctx, ArgValues[0]); return handleLValueToRValueConversion( Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(), RHS, Result); } // Reserve space for the struct members. if (!RD->isUnion() && !Result.hasValue()) Result = APValue(APValue::UninitStruct(), RD->getNumBases(), std::distance(RD->field_begin(), RD->field_end())); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); // A scope for temporaries lifetime-extended by reference members. BlockScopeRAII LifetimeExtendedScope(Info); bool Success = true; unsigned BasesSeen = 0; #ifndef NDEBUG CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); #endif for (const auto *I : Definition->inits()) { LValue Subobject = This; LValue SubobjectParent = This; APValue *Value = &Result; // Determine the subobject to initialize. FieldDecl *FD = nullptr; if (I->isBaseInitializer()) { QualType BaseType(I->getBaseClass(), 0); #ifndef NDEBUG // Non-virtual base classes are initialized in the order in the class // definition. We have already checked for virtual base classes. assert(!BaseIt->isVirtual() && "virtual base for literal type"); assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && "base class initializers not in expected order"); ++BaseIt; #endif if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD, BaseType->getAsCXXRecordDecl(), &Layout)) return false; Value = &Result.getStructBase(BasesSeen++); } else if ((FD = I->getMember())) { if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout)) return false; if (RD->isUnion()) { Result = APValue(FD); Value = &Result.getUnionValue(); } else { Value = &Result.getStructField(FD->getFieldIndex()); } } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) { // Walk the indirect field decl's chain to find the object to initialize, // and make sure we've initialized every step along it. auto IndirectFieldChain = IFD->chain(); for (auto *C : IndirectFieldChain) { FD = cast(C); CXXRecordDecl *CD = cast(FD->getParent()); // Switch the union field if it differs. This happens if we had // preceding zero-initialization, and we're now initializing a union // subobject other than the first. // FIXME: In this case, the values of the other subobjects are // specified, since zero-initialization sets all padding bits to zero. if (!Value->hasValue() || (Value->isUnion() && Value->getUnionField() != FD)) { if (CD->isUnion()) *Value = APValue(FD); else *Value = APValue(APValue::UninitStruct(), CD->getNumBases(), std::distance(CD->field_begin(), CD->field_end())); } // Store Subobject as its parent before updating it for the last element // in the chain. if (C == IndirectFieldChain.back()) SubobjectParent = Subobject; if (!HandleLValueMember(Info, I->getInit(), Subobject, FD)) return false; if (CD->isUnion()) Value = &Value->getUnionValue(); else Value = &Value->getStructField(FD->getFieldIndex()); } } else { llvm_unreachable("unknown base initializer kind"); } // Need to override This for implicit field initializers as in this case // This refers to innermost anonymous struct/union containing initializer, // not to currently constructed class. const Expr *Init = I->getInit(); ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent, isa(Init)); FullExpressionRAII InitScope(Info); if (!EvaluateInPlace(*Value, Info, Subobject, Init) || (FD && FD->isBitField() && !truncateBitfieldValue(Info, Init, *Value, FD))) { // If we're checking for a potential constant expression, evaluate all // initializers even if some of them fail. if (!Info.noteFailure()) return false; Success = false; } // This is the point at which the dynamic type of the object becomes this // class type. if (I->isBaseInitializer() && BasesSeen == RD->getNumBases()) EvalObj.finishedConstructingBases(); } return Success && EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed; } static bool HandleConstructorCall(const Expr *E, const LValue &This, ArrayRef Args, const CXXConstructorDecl *Definition, EvalInfo &Info, APValue &Result) { ArgVector ArgValues(Args.size()); if (!EvaluateArgs(Args, ArgValues, Info, Definition)) return false; return HandleConstructorCall(E, This, ArgValues.data(), Definition, Info, Result); } //===----------------------------------------------------------------------===// // Generic Evaluation //===----------------------------------------------------------------------===// namespace { class BitCastBuffer { // FIXME: We're going to need bit-level granularity when we support // bit-fields. // FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but // we don't support a host or target where that is the case. Still, we should // use a more generic type in case we ever do. SmallVector, 32> Bytes; static_assert(std::numeric_limits::digits >= 8, "Need at least 8 bit unsigned char"); bool TargetIsLittleEndian; public: BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian) : Bytes(Width.getQuantity()), TargetIsLittleEndian(TargetIsLittleEndian) {} LLVM_NODISCARD bool readObject(CharUnits Offset, CharUnits Width, SmallVectorImpl &Output) const { for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) { // If a byte of an integer is uninitialized, then the whole integer is // uninitalized. if (!Bytes[I.getQuantity()]) return false; Output.push_back(*Bytes[I.getQuantity()]); } if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian) std::reverse(Output.begin(), Output.end()); return true; } void writeObject(CharUnits Offset, SmallVectorImpl &Input) { if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian) std::reverse(Input.begin(), Input.end()); size_t Index = 0; for (unsigned char Byte : Input) { assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?"); Bytes[Offset.getQuantity() + Index] = Byte; ++Index; } } size_t size() { return Bytes.size(); } }; /// Traverse an APValue to produce an BitCastBuffer, emulating how the current /// target would represent the value at runtime. class APValueToBufferConverter { EvalInfo &Info; BitCastBuffer Buffer; const CastExpr *BCE; APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth, const CastExpr *BCE) : Info(Info), Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()), BCE(BCE) {} bool visit(const APValue &Val, QualType Ty) { return visit(Val, Ty, CharUnits::fromQuantity(0)); } // Write out Val with type Ty into Buffer starting at Offset. bool visit(const APValue &Val, QualType Ty, CharUnits Offset) { assert((size_t)Offset.getQuantity() <= Buffer.size()); // As a special case, nullptr_t has an indeterminate value. if (Ty->isNullPtrType()) return true; // Dig through Src to find the byte at SrcOffset. switch (Val.getKind()) { case APValue::Indeterminate: case APValue::None: return true; case APValue::Int: return visitInt(Val.getInt(), Ty, Offset); case APValue::Float: return visitFloat(Val.getFloat(), Ty, Offset); case APValue::Array: return visitArray(Val, Ty, Offset); case APValue::Struct: return visitRecord(Val, Ty, Offset); case APValue::ComplexInt: case APValue::ComplexFloat: case APValue::Vector: case APValue::FixedPoint: // FIXME: We should support these. case APValue::Union: case APValue::MemberPointer: case APValue::AddrLabelDiff: { Info.FFDiag(BCE->getBeginLoc(), diag::note_constexpr_bit_cast_unsupported_type) << Ty; return false; } case APValue::LValue: llvm_unreachable("LValue subobject in bit_cast?"); } llvm_unreachable("Unhandled APValue::ValueKind"); } bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) { const RecordDecl *RD = Ty->getAsRecordDecl(); const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); // Visit the base classes. if (auto *CXXRD = dyn_cast(RD)) { for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) { const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I]; CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl(); if (!visitRecord(Val.getStructBase(I), BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset)) return false; } } // Visit the fields. unsigned FieldIdx = 0; for (FieldDecl *FD : RD->fields()) { if (FD->isBitField()) { Info.FFDiag(BCE->getBeginLoc(), diag::note_constexpr_bit_cast_unsupported_bitfield); return false; } uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx); assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 && "only bit-fields can have sub-char alignment"); CharUnits FieldOffset = Info.Ctx.toCharUnitsFromBits(FieldOffsetBits) + Offset; QualType FieldTy = FD->getType(); if (!visit(Val.getStructField(FieldIdx), FieldTy, FieldOffset)) return false; ++FieldIdx; } return true; } bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) { const auto *CAT = dyn_cast_or_null(Ty->getAsArrayTypeUnsafe()); if (!CAT) return false; CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType()); unsigned NumInitializedElts = Val.getArrayInitializedElts(); unsigned ArraySize = Val.getArraySize(); // First, initialize the initialized elements. for (unsigned I = 0; I != NumInitializedElts; ++I) { const APValue &SubObj = Val.getArrayInitializedElt(I); if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth)) return false; } // Next, initialize the rest of the array using the filler. if (Val.hasArrayFiller()) { const APValue &Filler = Val.getArrayFiller(); for (unsigned I = NumInitializedElts; I != ArraySize; ++I) { if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth)) return false; } } return true; } bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) { CharUnits Width = Info.Ctx.getTypeSizeInChars(Ty); SmallVector Bytes(Width.getQuantity()); llvm::StoreIntToMemory(Val, &*Bytes.begin(), Width.getQuantity()); Buffer.writeObject(Offset, Bytes); return true; } bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) { APSInt AsInt(Val.bitcastToAPInt()); return visitInt(AsInt, Ty, Offset); } public: static Optional convert(EvalInfo &Info, const APValue &Src, const CastExpr *BCE) { CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType()); APValueToBufferConverter Converter(Info, DstSize, BCE); if (!Converter.visit(Src, BCE->getSubExpr()->getType())) return None; return Converter.Buffer; } }; /// Write an BitCastBuffer into an APValue. class BufferToAPValueConverter { EvalInfo &Info; const BitCastBuffer &Buffer; const CastExpr *BCE; BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer, const CastExpr *BCE) : Info(Info), Buffer(Buffer), BCE(BCE) {} // Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast // with an invalid type, so anything left is a deficiency on our part (FIXME). // Ideally this will be unreachable. llvm::NoneType unsupportedType(QualType Ty) { Info.FFDiag(BCE->getBeginLoc(), diag::note_constexpr_bit_cast_unsupported_type) << Ty; return None; } Optional visit(const BuiltinType *T, CharUnits Offset, const EnumType *EnumSugar = nullptr) { if (T->isNullPtrType()) { uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QualType(T, 0)); return APValue((Expr *)nullptr, /*Offset=*/CharUnits::fromQuantity(NullValue), APValue::NoLValuePath{}, /*IsNullPtr=*/true); } CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T); SmallVector Bytes; if (!Buffer.readObject(Offset, SizeOf, Bytes)) { // If this is std::byte or unsigned char, then its okay to store an // indeterminate value. bool IsStdByte = EnumSugar && EnumSugar->isStdByteType(); bool IsUChar = !EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) || T->isSpecificBuiltinType(BuiltinType::Char_U)); if (!IsStdByte && !IsUChar) { QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0); Info.FFDiag(BCE->getExprLoc(), diag::note_constexpr_bit_cast_indet_dest) << DisplayType << Info.Ctx.getLangOpts().CharIsSigned; return None; } return APValue::IndeterminateValue(); } APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true); llvm::LoadIntFromMemory(Val, &*Bytes.begin(), Bytes.size()); if (T->isIntegralOrEnumerationType()) { Val.setIsSigned(T->isSignedIntegerOrEnumerationType()); return APValue(Val); } if (T->isRealFloatingType()) { const llvm::fltSemantics &Semantics = Info.Ctx.getFloatTypeSemantics(QualType(T, 0)); return APValue(APFloat(Semantics, Val)); } return unsupportedType(QualType(T, 0)); } Optional visit(const RecordType *RTy, CharUnits Offset) { const RecordDecl *RD = RTy->getAsRecordDecl(); const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); unsigned NumBases = 0; if (auto *CXXRD = dyn_cast(RD)) NumBases = CXXRD->getNumBases(); APValue ResultVal(APValue::UninitStruct(), NumBases, std::distance(RD->field_begin(), RD->field_end())); // Visit the base classes. if (auto *CXXRD = dyn_cast(RD)) { for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) { const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I]; CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl(); if (BaseDecl->isEmpty() || Info.Ctx.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero()) continue; Optional SubObj = visitType( BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset); if (!SubObj) return None; ResultVal.getStructBase(I) = *SubObj; } } // Visit the fields. unsigned FieldIdx = 0; for (FieldDecl *FD : RD->fields()) { // FIXME: We don't currently support bit-fields. A lot of the logic for // this is in CodeGen, so we need to factor it around. if (FD->isBitField()) { Info.FFDiag(BCE->getBeginLoc(), diag::note_constexpr_bit_cast_unsupported_bitfield); return None; } uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx); assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0); CharUnits FieldOffset = CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) + Offset; QualType FieldTy = FD->getType(); Optional SubObj = visitType(FieldTy, FieldOffset); if (!SubObj) return None; ResultVal.getStructField(FieldIdx) = *SubObj; ++FieldIdx; } return ResultVal; } Optional visit(const EnumType *Ty, CharUnits Offset) { QualType RepresentationType = Ty->getDecl()->getIntegerType(); assert(!RepresentationType.isNull() && "enum forward decl should be caught by Sema"); const BuiltinType *AsBuiltin = RepresentationType.getCanonicalType()->getAs(); assert(AsBuiltin && "non-integral enum underlying type?"); // Recurse into the underlying type. Treat std::byte transparently as // unsigned char. return visit(AsBuiltin, Offset, /*EnumTy=*/Ty); } Optional visit(const ConstantArrayType *Ty, CharUnits Offset) { size_t Size = Ty->getSize().getLimitedValue(); CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType()); APValue ArrayValue(APValue::UninitArray(), Size, Size); for (size_t I = 0; I != Size; ++I) { Optional ElementValue = visitType(Ty->getElementType(), Offset + I * ElementWidth); if (!ElementValue) return None; ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue); } return ArrayValue; } Optional visit(const Type *Ty, CharUnits Offset) { return unsupportedType(QualType(Ty, 0)); } Optional visitType(QualType Ty, CharUnits Offset) { QualType Can = Ty.getCanonicalType(); switch (Can->getTypeClass()) { #define TYPE(Class, Base) \ case Type::Class: \ return visit(cast(Can.getTypePtr()), Offset); #define ABSTRACT_TYPE(Class, Base) #define NON_CANONICAL_TYPE(Class, Base) \ case Type::Class: \ llvm_unreachable("non-canonical type should be impossible!"); #define DEPENDENT_TYPE(Class, Base) \ case Type::Class: \ llvm_unreachable( \ "dependent types aren't supported in the constant evaluator!"); #define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \ case Type::Class: \ llvm_unreachable("either dependent or not canonical!"); #include "clang/AST/TypeNodes.def" } llvm_unreachable("Unhandled Type::TypeClass"); } public: // Pull out a full value of type DstType. static Optional convert(EvalInfo &Info, BitCastBuffer &Buffer, const CastExpr *BCE) { BufferToAPValueConverter Converter(Info, Buffer, BCE); return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(0)); } }; static bool checkBitCastConstexprEligibilityType(SourceLocation Loc, QualType Ty, EvalInfo *Info, const ASTContext &Ctx, bool CheckingDest) { Ty = Ty.getCanonicalType(); auto diag = [&](int Reason) { if (Info) Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type) << CheckingDest << (Reason == 4) << Reason; return false; }; auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) { if (Info) Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype) << NoteTy << Construct << Ty; return false; }; if (Ty->isUnionType()) return diag(0); if (Ty->isPointerType()) return diag(1); if (Ty->isMemberPointerType()) return diag(2); if (Ty.isVolatileQualified()) return diag(3); if (RecordDecl *Record = Ty->getAsRecordDecl()) { if (auto *CXXRD = dyn_cast(Record)) { for (CXXBaseSpecifier &BS : CXXRD->bases()) if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx, CheckingDest)) return note(1, BS.getType(), BS.getBeginLoc()); } for (FieldDecl *FD : Record->fields()) { if (FD->getType()->isReferenceType()) return diag(4); if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx, CheckingDest)) return note(0, FD->getType(), FD->getBeginLoc()); } } if (Ty->isArrayType() && !checkBitCastConstexprEligibilityType(Loc, Ctx.getBaseElementType(Ty), Info, Ctx, CheckingDest)) return false; return true; } static bool checkBitCastConstexprEligibility(EvalInfo *Info, const ASTContext &Ctx, const CastExpr *BCE) { bool DestOK = checkBitCastConstexprEligibilityType( BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true); bool SourceOK = DestOK && checkBitCastConstexprEligibilityType( BCE->getBeginLoc(), BCE->getSubExpr()->getType(), Info, Ctx, false); return SourceOK; } static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue, APValue &SourceValue, const CastExpr *BCE) { assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 && "no host or target supports non 8-bit chars"); assert(SourceValue.isLValue() && "LValueToRValueBitcast requires an lvalue operand!"); if (!checkBitCastConstexprEligibility(&Info, Info.Ctx, BCE)) return false; LValue SourceLValue; APValue SourceRValue; SourceLValue.setFrom(Info.Ctx, SourceValue); if (!handleLValueToRValueConversion(Info, BCE, BCE->getSubExpr()->getType().withConst(), SourceLValue, SourceRValue)) return false; // Read out SourceValue into a char buffer. Optional Buffer = APValueToBufferConverter::convert(Info, SourceRValue, BCE); if (!Buffer) return false; // Write out the buffer into a new APValue. Optional MaybeDestValue = BufferToAPValueConverter::convert(Info, *Buffer, BCE); if (!MaybeDestValue) return false; DestValue = std::move(*MaybeDestValue); return true; } template class ExprEvaluatorBase : public ConstStmtVisitor { private: Derived &getDerived() { return static_cast(*this); } bool DerivedSuccess(const APValue &V, const Expr *E) { return getDerived().Success(V, E); } bool DerivedZeroInitialization(const Expr *E) { return getDerived().ZeroInitialization(E); } // Check whether a conditional operator with a non-constant condition is a // potential constant expression. If neither arm is a potential constant // expression, then the conditional operator is not either. template void CheckPotentialConstantConditional(const ConditionalOperator *E) { assert(Info.checkingPotentialConstantExpression()); // Speculatively evaluate both arms. SmallVector Diag; { SpeculativeEvaluationRAII Speculate(Info, &Diag); StmtVisitorTy::Visit(E->getFalseExpr()); if (Diag.empty()) return; } { SpeculativeEvaluationRAII Speculate(Info, &Diag); Diag.clear(); StmtVisitorTy::Visit(E->getTrueExpr()); if (Diag.empty()) return; } Error(E, diag::note_constexpr_conditional_never_const); } template bool HandleConditionalOperator(const ConditionalOperator *E) { bool BoolResult; if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) { CheckPotentialConstantConditional(E); return false; } if (Info.noteFailure()) { StmtVisitorTy::Visit(E->getTrueExpr()); StmtVisitorTy::Visit(E->getFalseExpr()); } return false; } Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); return StmtVisitorTy::Visit(EvalExpr); } protected: EvalInfo &Info; typedef ConstStmtVisitor StmtVisitorTy; typedef ExprEvaluatorBase ExprEvaluatorBaseTy; OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { return Info.CCEDiag(E, D); } bool ZeroInitialization(const Expr *E) { return Error(E); } public: ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} EvalInfo &getEvalInfo() { return Info; } /// Report an evaluation error. This should only be called when an error is /// first discovered. When propagating an error, just return false. bool Error(const Expr *E, diag::kind D) { Info.FFDiag(E, D); return false; } bool Error(const Expr *E) { return Error(E, diag::note_invalid_subexpr_in_const_expr); } bool VisitStmt(const Stmt *) { llvm_unreachable("Expression evaluator should not be called on stmts"); } bool VisitExpr(const Expr *E) { return Error(E); } bool VisitConstantExpr(const ConstantExpr *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitParenExpr(const ParenExpr *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitUnaryExtension(const UnaryOperator *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitUnaryPlus(const UnaryOperator *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitChooseExpr(const ChooseExpr *E) { return StmtVisitorTy::Visit(E->getChosenSubExpr()); } bool VisitGenericSelectionExpr(const GenericSelectionExpr *E) { return StmtVisitorTy::Visit(E->getResultExpr()); } bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) { return StmtVisitorTy::Visit(E->getReplacement()); } bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) { TempVersionRAII RAII(*Info.CurrentCall); SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope); return StmtVisitorTy::Visit(E->getExpr()); } bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) { TempVersionRAII RAII(*Info.CurrentCall); // The initializer may not have been parsed yet, or might be erroneous. if (!E->getExpr()) return Error(E); SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope); return StmtVisitorTy::Visit(E->getExpr()); } // We cannot create any objects for which cleanups are required, so there is // nothing to do here; all cleanups must come from unevaluated subexpressions. bool VisitExprWithCleanups(const ExprWithCleanups *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; return static_cast(this)->VisitCastExpr(E); } bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { if (!Info.Ctx.getLangOpts().CPlusPlus2a) CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; return static_cast(this)->VisitCastExpr(E); } bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) { return static_cast(this)->VisitCastExpr(E); } bool VisitBinaryOperator(const BinaryOperator *E) { switch (E->getOpcode()) { default: return Error(E); case BO_Comma: VisitIgnoredValue(E->getLHS()); return StmtVisitorTy::Visit(E->getRHS()); case BO_PtrMemD: case BO_PtrMemI: { LValue Obj; if (!HandleMemberPointerAccess(Info, E, Obj)) return false; APValue Result; if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) return false; return DerivedSuccess(Result, E); } } } bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { // Evaluate and cache the common expression. We treat it as a temporary, // even though it's not quite the same thing. if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false), Info, E->getCommon())) return false; return HandleConditionalOperator(E); } bool VisitConditionalOperator(const ConditionalOperator *E) { bool IsBcpCall = false; // If the condition (ignoring parens) is a __builtin_constant_p call, // the result is a constant expression if it can be folded without // side-effects. This is an important GNU extension. See GCC PR38377 // for discussion. if (const CallExpr *CallCE = dyn_cast(E->getCond()->IgnoreParenCasts())) if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) IsBcpCall = true; // Always assume __builtin_constant_p(...) ? ... : ... is a potential // constant expression; we can't check whether it's potentially foldable. // FIXME: We should instead treat __builtin_constant_p as non-constant if // it would return 'false' in this mode. if (Info.checkingPotentialConstantExpression() && IsBcpCall) return false; FoldConstant Fold(Info, IsBcpCall); if (!HandleConditionalOperator(E)) { Fold.keepDiagnostics(); return false; } return true; } bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) { if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E)) return DerivedSuccess(*Value, E); const Expr *Source = E->getSourceExpr(); if (!Source) return Error(E); if (Source == E) { // sanity checking. assert(0 && "OpaqueValueExpr recursively refers to itself"); return Error(E); } return StmtVisitorTy::Visit(Source); } bool VisitCallExpr(const CallExpr *E) { APValue Result; if (!handleCallExpr(E, Result, nullptr)) return false; return DerivedSuccess(Result, E); } bool handleCallExpr(const CallExpr *E, APValue &Result, const LValue *ResultSlot) { const Expr *Callee = E->getCallee()->IgnoreParens(); QualType CalleeType = Callee->getType(); const FunctionDecl *FD = nullptr; LValue *This = nullptr, ThisVal; auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); bool HasQualifier = false; // Extract function decl and 'this' pointer from the callee. if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { const CXXMethodDecl *Member = nullptr; if (const MemberExpr *ME = dyn_cast(Callee)) { // Explicit bound member calls, such as x.f() or p->g(); if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) return false; Member = dyn_cast(ME->getMemberDecl()); if (!Member) return Error(Callee); This = &ThisVal; HasQualifier = ME->hasQualifier(); } else if (const BinaryOperator *BE = dyn_cast(Callee)) { // Indirect bound member calls ('.*' or '->*'). Member = dyn_cast_or_null( HandleMemberPointerAccess(Info, BE, ThisVal, false)); if (!Member) return Error(Callee); This = &ThisVal; } else return Error(Callee); FD = Member; } else if (CalleeType->isFunctionPointerType()) { LValue Call; if (!EvaluatePointer(Callee, Call, Info)) return false; if (!Call.getLValueOffset().isZero()) return Error(Callee); FD = dyn_cast_or_null( Call.getLValueBase().dyn_cast()); if (!FD) return Error(Callee); // Don't call function pointers which have been cast to some other type. // Per DR (no number yet), the caller and callee can differ in noexcept. if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec( CalleeType->getPointeeType(), FD->getType())) { return Error(E); } // Overloaded operator calls to member functions are represented as normal // calls with '*this' as the first argument. const CXXMethodDecl *MD = dyn_cast(FD); if (MD && !MD->isStatic()) { // FIXME: When selecting an implicit conversion for an overloaded // operator delete, we sometimes try to evaluate calls to conversion // operators without a 'this' parameter! if (Args.empty()) return Error(E); if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) return false; This = &ThisVal; Args = Args.slice(1); } else if (MD && MD->isLambdaStaticInvoker()) { // Map the static invoker for the lambda back to the call operator. // Conveniently, we don't have to slice out the 'this' argument (as is // being done for the non-static case), since a static member function // doesn't have an implicit argument passed in. const CXXRecordDecl *ClosureClass = MD->getParent(); assert( ClosureClass->captures_begin() == ClosureClass->captures_end() && "Number of captures must be zero for conversion to function-ptr"); const CXXMethodDecl *LambdaCallOp = ClosureClass->getLambdaCallOperator(); // Set 'FD', the function that will be called below, to the call // operator. If the closure object represents a generic lambda, find // the corresponding specialization of the call operator. if (ClosureClass->isGenericLambda()) { assert(MD->isFunctionTemplateSpecialization() && "A generic lambda's static-invoker function must be a " "template specialization"); const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs(); FunctionTemplateDecl *CallOpTemplate = LambdaCallOp->getDescribedFunctionTemplate(); void *InsertPos = nullptr; FunctionDecl *CorrespondingCallOpSpecialization = CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos); assert(CorrespondingCallOpSpecialization && "We must always have a function call operator specialization " "that corresponds to our static invoker specialization"); FD = cast(CorrespondingCallOpSpecialization); } else FD = LambdaCallOp; } } else return Error(E); SmallVector CovariantAdjustmentPath; if (This) { auto *NamedMember = dyn_cast(FD); if (NamedMember && NamedMember->isVirtual() && !HasQualifier) { // Perform virtual dispatch, if necessary. FD = HandleVirtualDispatch(Info, E, *This, NamedMember, CovariantAdjustmentPath); if (!FD) return false; } else { // Check that the 'this' pointer points to an object of the right type. if (!checkNonVirtualMemberCallThisPointer(Info, E, *This)) return false; } } const FunctionDecl *Definition = nullptr; Stmt *Body = FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) || !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info, Result, ResultSlot)) return false; if (!CovariantAdjustmentPath.empty() && !HandleCovariantReturnAdjustment(Info, E, Result, CovariantAdjustmentPath)) return false; return true; } bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { return StmtVisitorTy::Visit(E->getInitializer()); } bool VisitInitListExpr(const InitListExpr *E) { if (E->getNumInits() == 0) return DerivedZeroInitialization(E); if (E->getNumInits() == 1) return StmtVisitorTy::Visit(E->getInit(0)); return Error(E); } bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { return DerivedZeroInitialization(E); } bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { return DerivedZeroInitialization(E); } bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { return DerivedZeroInitialization(E); } /// A member expression where the object is a prvalue is itself a prvalue. bool VisitMemberExpr(const MemberExpr *E) { assert(!Info.Ctx.getLangOpts().CPlusPlus11 && "missing temporary materialization conversion"); assert(!E->isArrow() && "missing call to bound member function?"); APValue Val; if (!Evaluate(Val, Info, E->getBase())) return false; QualType BaseTy = E->getBase()->getType(); const FieldDecl *FD = dyn_cast(E->getMemberDecl()); if (!FD) return Error(E); assert(!FD->getType()->isReferenceType() && "prvalue reference?"); assert(BaseTy->castAs()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"); // Note: there is no lvalue base here. But this case should only ever // happen in C or in C++98, where we cannot be evaluating a constexpr // constructor, which is the only case the base matters. CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy); SubobjectDesignator Designator(BaseTy); Designator.addDeclUnchecked(FD); APValue Result; return extractSubobject(Info, E, Obj, Designator, Result) && DerivedSuccess(Result, E); } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: break; case CK_AtomicToNonAtomic: { APValue AtomicVal; // This does not need to be done in place even for class/array types: // atomic-to-non-atomic conversion implies copying the object // representation. if (!Evaluate(AtomicVal, Info, E->getSubExpr())) return false; return DerivedSuccess(AtomicVal, E); } case CK_NoOp: case CK_UserDefinedConversion: return StmtVisitorTy::Visit(E->getSubExpr()); case CK_LValueToRValue: { LValue LVal; if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) return false; APValue RVal; // Note, we use the subexpression's type in order to retain cv-qualifiers. if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), LVal, RVal)) return false; return DerivedSuccess(RVal, E); } case CK_LValueToRValueBitCast: { APValue DestValue, SourceValue; if (!Evaluate(SourceValue, Info, E->getSubExpr())) return false; if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, E)) return false; return DerivedSuccess(DestValue, E); } } return Error(E); } bool VisitUnaryPostInc(const UnaryOperator *UO) { return VisitUnaryPostIncDec(UO); } bool VisitUnaryPostDec(const UnaryOperator *UO) { return VisitUnaryPostIncDec(UO); } bool VisitUnaryPostIncDec(const UnaryOperator *UO) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(UO); LValue LVal; if (!EvaluateLValue(UO->getSubExpr(), LVal, Info)) return false; APValue RVal; if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(), UO->isIncrementOp(), &RVal)) return false; return DerivedSuccess(RVal, UO); } bool VisitStmtExpr(const StmtExpr *E) { // We will have checked the full-expressions inside the statement expression // when they were completed, and don't need to check them again now. if (Info.checkingForUndefinedBehavior()) return Error(E); BlockScopeRAII Scope(Info); const CompoundStmt *CS = E->getSubStmt(); if (CS->body_empty()) return true; for (CompoundStmt::const_body_iterator BI = CS->body_begin(), BE = CS->body_end(); /**/; ++BI) { if (BI + 1 == BE) { const Expr *FinalExpr = dyn_cast(*BI); if (!FinalExpr) { Info.FFDiag((*BI)->getBeginLoc(), diag::note_constexpr_stmt_expr_unsupported); return false; } return this->Visit(FinalExpr); } APValue ReturnValue; StmtResult Result = { ReturnValue, nullptr }; EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI); if (ESR != ESR_Succeeded) { // FIXME: If the statement-expression terminated due to 'return', // 'break', or 'continue', it would be nice to propagate that to // the outer statement evaluation rather than bailing out. if (ESR != ESR_Failed) Info.FFDiag((*BI)->getBeginLoc(), diag::note_constexpr_stmt_expr_unsupported); return false; } } llvm_unreachable("Return from function from the loop above."); } /// Visit a value which is evaluated, but whose value is ignored. void VisitIgnoredValue(const Expr *E) { EvaluateIgnoredValue(Info, E); } /// Potentially visit a MemberExpr's base expression. void VisitIgnoredBaseExpression(const Expr *E) { // While MSVC doesn't evaluate the base expression, it does diagnose the // presence of side-effecting behavior. if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx)) return; VisitIgnoredValue(E); } }; } // namespace //===----------------------------------------------------------------------===// // Common base class for lvalue and temporary evaluation. //===----------------------------------------------------------------------===// namespace { template class LValueExprEvaluatorBase : public ExprEvaluatorBase { protected: LValue &Result; bool InvalidBaseOK; typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; typedef ExprEvaluatorBase ExprEvaluatorBaseTy; bool Success(APValue::LValueBase B) { Result.set(B); return true; } bool evaluatePointer(const Expr *E, LValue &Result) { return EvaluatePointer(E, Result, this->Info, InvalidBaseOK); } public: LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) : ExprEvaluatorBaseTy(Info), Result(Result), InvalidBaseOK(InvalidBaseOK) {} bool Success(const APValue &V, const Expr *E) { Result.setFrom(this->Info.Ctx, V); return true; } bool VisitMemberExpr(const MemberExpr *E) { // Handle non-static data members. QualType BaseTy; bool EvalOK; if (E->isArrow()) { EvalOK = evaluatePointer(E->getBase(), Result); BaseTy = E->getBase()->getType()->castAs()->getPointeeType(); } else if (E->getBase()->isRValue()) { assert(E->getBase()->getType()->isRecordType()); EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info); BaseTy = E->getBase()->getType(); } else { EvalOK = this->Visit(E->getBase()); BaseTy = E->getBase()->getType(); } if (!EvalOK) { if (!InvalidBaseOK) return false; Result.setInvalid(E); return true; } const ValueDecl *MD = E->getMemberDecl(); if (const FieldDecl *FD = dyn_cast(E->getMemberDecl())) { assert(BaseTy->getAs()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"); (void)BaseTy; if (!HandleLValueMember(this->Info, E, Result, FD)) return false; } else if (const IndirectFieldDecl *IFD = dyn_cast(MD)) { if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) return false; } else return this->Error(E); if (MD->getType()->isReferenceType()) { APValue RefValue; if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result, RefValue)) return false; return Success(RefValue, E); } return true; } bool VisitBinaryOperator(const BinaryOperator *E) { switch (E->getOpcode()) { default: return ExprEvaluatorBaseTy::VisitBinaryOperator(E); case BO_PtrMemD: case BO_PtrMemI: return HandleMemberPointerAccess(this->Info, E, Result); } } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_DerivedToBase: case CK_UncheckedDerivedToBase: if (!this->Visit(E->getSubExpr())) return false; // Now figure out the necessary offset to add to the base LV to get from // the derived class to the base class. return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(), Result); } } }; } //===----------------------------------------------------------------------===// // LValue Evaluation // // This is used for evaluating lvalues (in C and C++), xvalues (in C++11), // function designators (in C), decl references to void objects (in C), and // temporaries (if building with -Wno-address-of-temporary). // // LValue evaluation produces values comprising a base expression of one of the // following types: // - Declarations // * VarDecl // * FunctionDecl // - Literals // * CompoundLiteralExpr in C (and in global scope in C++) // * StringLiteral // * PredefinedExpr // * ObjCStringLiteralExpr // * ObjCEncodeExpr // * AddrLabelExpr // * BlockExpr // * CallExpr for a MakeStringConstant builtin // - typeid(T) expressions, as TypeInfoLValues // - Locals and temporaries // * MaterializeTemporaryExpr // * Any Expr, with a CallIndex indicating the function in which the temporary // was evaluated, for cases where the MaterializeTemporaryExpr is missing // from the AST (FIXME). // * A MaterializeTemporaryExpr that has static storage duration, with no // CallIndex, for a lifetime-extended temporary. // plus an offset in bytes. //===----------------------------------------------------------------------===// namespace { class LValueExprEvaluator : public LValueExprEvaluatorBase { public: LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) : LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {} bool VisitVarDecl(const Expr *E, const VarDecl *VD); bool VisitUnaryPreIncDec(const UnaryOperator *UO); bool VisitDeclRefExpr(const DeclRefExpr *E); bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); bool VisitMemberExpr(const MemberExpr *E); bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); bool VisitUnaryDeref(const UnaryOperator *E); bool VisitUnaryReal(const UnaryOperator *E); bool VisitUnaryImag(const UnaryOperator *E); bool VisitUnaryPreInc(const UnaryOperator *UO) { return VisitUnaryPreIncDec(UO); } bool VisitUnaryPreDec(const UnaryOperator *UO) { return VisitUnaryPreIncDec(UO); } bool VisitBinAssign(const BinaryOperator *BO); bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO); bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return LValueExprEvaluatorBaseTy::VisitCastExpr(E); case CK_LValueBitCast: this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; if (!Visit(E->getSubExpr())) return false; Result.Designator.setInvalid(); return true; case CK_BaseToDerived: if (!Visit(E->getSubExpr())) return false; return HandleBaseToDerivedCast(Info, E, Result); case CK_Dynamic: if (!Visit(E->getSubExpr())) return false; return HandleDynamicCast(Info, cast(E), Result); } } }; } // end anonymous namespace /// Evaluate an expression as an lvalue. This can be legitimately called on /// expressions which are not glvalues, in three cases: /// * function designators in C, and /// * "extern void" objects /// * @selector() expressions in Objective-C static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info, bool InvalidBaseOK) { assert(E->isGLValue() || E->getType()->isFunctionType() || E->getType()->isVoidType() || isa(E)); return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E); } bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { if (const FunctionDecl *FD = dyn_cast(E->getDecl())) return Success(FD); if (const VarDecl *VD = dyn_cast(E->getDecl())) return VisitVarDecl(E, VD); if (const BindingDecl *BD = dyn_cast(E->getDecl())) return Visit(BD->getBinding()); return Error(E); } bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { // If we are within a lambda's call operator, check whether the 'VD' referred // to within 'E' actually represents a lambda-capture that maps to a // data-member/field within the closure object, and if so, evaluate to the // field or what the field refers to. if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) && isa(E) && cast(E)->refersToEnclosingVariableOrCapture()) { // We don't always have a complete capture-map when checking or inferring if // the function call operator meets the requirements of a constexpr function // - but we don't need to evaluate the captures to determine constexprness // (dcl.constexpr C++17). if (Info.checkingPotentialConstantExpression()) return false; if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) { // Start with 'Result' referring to the complete closure object... Result = *Info.CurrentCall->This; // ... then update it to refer to the field of the closure object // that represents the capture. if (!HandleLValueMember(Info, E, Result, FD)) return false; // And if the field is of reference type, update 'Result' to refer to what // the field refers to. if (FD->getType()->isReferenceType()) { APValue RVal; if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result, RVal)) return false; Result.setFrom(Info.Ctx, RVal); } return true; } } CallStackFrame *Frame = nullptr; if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) { // Only if a local variable was declared in the function currently being // evaluated, do we expect to be able to find its value in the current // frame. (Otherwise it was likely declared in an enclosing context and // could either have a valid evaluatable value (for e.g. a constexpr // variable) or be ill-formed (and trigger an appropriate evaluation // diagnostic)). if (Info.CurrentCall->Callee && Info.CurrentCall->Callee->Equals(VD->getDeclContext())) { Frame = Info.CurrentCall; } } if (!VD->getType()->isReferenceType()) { if (Frame) { Result.set({VD, Frame->Index, Info.CurrentCall->getCurrentTemporaryVersion(VD)}); return true; } return Success(VD); } APValue *V; if (!evaluateVarDeclInit(Info, E, VD, Frame, V, nullptr)) return false; if (!V->hasValue()) { // FIXME: Is it possible for V to be indeterminate here? If so, we should // adjust the diagnostic to say that. if (!Info.checkingPotentialConstantExpression()) Info.FFDiag(E, diag::note_constexpr_use_uninit_reference); return false; } return Success(*V, E); } bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( const MaterializeTemporaryExpr *E) { // Walk through the expression to find the materialized temporary itself. SmallVector CommaLHSs; SmallVector Adjustments; const Expr *Inner = E->GetTemporaryExpr()-> skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); // If we passed any comma operators, evaluate their LHSs. for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I) if (!EvaluateIgnoredValue(Info, CommaLHSs[I])) return false; // A materialized temporary with static storage duration can appear within the // result of a constant expression evaluation, so we need to preserve its // value for use outside this evaluation. APValue *Value; if (E->getStorageDuration() == SD_Static) { Value = Info.Ctx.getMaterializedTemporaryValue(E, true); *Value = APValue(); Result.set(E); } else { Value = &createTemporary(E, E->getStorageDuration() == SD_Automatic, Result, *Info.CurrentCall); } QualType Type = Inner->getType(); // Materialize the temporary itself. if (!EvaluateInPlace(*Value, Info, Result, Inner) || (E->getStorageDuration() == SD_Static && !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) { *Value = APValue(); return false; } // Adjust our lvalue to refer to the desired subobject. for (unsigned I = Adjustments.size(); I != 0; /**/) { --I; switch (Adjustments[I].Kind) { case SubobjectAdjustment::DerivedToBaseAdjustment: if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath, Type, Result)) return false; Type = Adjustments[I].DerivedToBase.BasePath->getType(); break; case SubobjectAdjustment::FieldAdjustment: if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field)) return false; Type = Adjustments[I].Field->getType(); break; case SubobjectAdjustment::MemberPointerAdjustment: if (!HandleMemberPointerAccess(this->Info, Type, Result, Adjustments[I].Ptr.RHS)) return false; Type = Adjustments[I].Ptr.MPT->getPointeeType(); break; } } return true; } bool LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) && "lvalue compound literal in c++?"); // Defer visiting the literal until the lvalue-to-rvalue conversion. We can // only see this when folding in C, so there's no standard to follow here. return Success(E); } bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { TypeInfoLValue TypeInfo; if (!E->isPotentiallyEvaluated()) { if (E->isTypeOperand()) TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr()); else TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr()); } else { if (!Info.Ctx.getLangOpts().CPlusPlus2a) { Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic) << E->getExprOperand()->getType() << E->getExprOperand()->getSourceRange(); } if (!Visit(E->getExprOperand())) return false; Optional DynType = ComputeDynamicType(Info, E, Result, AK_TypeId); if (!DynType) return false; TypeInfo = TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr()); } return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType())); } bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { return Success(E); } bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { // Handle static data members. if (const VarDecl *VD = dyn_cast(E->getMemberDecl())) { VisitIgnoredBaseExpression(E->getBase()); return VisitVarDecl(E, VD); } // Handle static member functions. if (const CXXMethodDecl *MD = dyn_cast(E->getMemberDecl())) { if (MD->isStatic()) { VisitIgnoredBaseExpression(E->getBase()); return Success(MD); } } // Handle non-static data members. return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); } bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { // FIXME: Deal with vectors as array subscript bases. if (E->getBase()->getType()->isVectorType()) return Error(E); bool Success = true; if (!evaluatePointer(E->getBase(), Result)) { if (!Info.noteFailure()) return false; Success = false; } APSInt Index; if (!EvaluateInteger(E->getIdx(), Index, Info)) return false; return Success && HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index); } bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { return evaluatePointer(E->getSubExpr(), Result); } bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { if (!Visit(E->getSubExpr())) return false; // __real is a no-op on scalar lvalues. if (E->getSubExpr()->getType()->isAnyComplexType()) HandleLValueComplexElement(Info, E, Result, E->getType(), false); return true; } bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { assert(E->getSubExpr()->getType()->isAnyComplexType() && "lvalue __imag__ on scalar?"); if (!Visit(E->getSubExpr())) return false; HandleLValueComplexElement(Info, E, Result, E->getType(), true); return true; } bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(UO); if (!this->Visit(UO->getSubExpr())) return false; return handleIncDec( this->Info, UO, Result, UO->getSubExpr()->getType(), UO->isIncrementOp(), nullptr); } bool LValueExprEvaluator::VisitCompoundAssignOperator( const CompoundAssignOperator *CAO) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(CAO); APValue RHS; // The overall lvalue result is the result of evaluating the LHS. if (!this->Visit(CAO->getLHS())) { if (Info.noteFailure()) Evaluate(RHS, this->Info, CAO->getRHS()); return false; } if (!Evaluate(RHS, this->Info, CAO->getRHS())) return false; return handleCompoundAssignment( this->Info, CAO, Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(), CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS); } bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(E); APValue NewVal; if (!this->Visit(E->getLHS())) { if (Info.noteFailure()) Evaluate(NewVal, this->Info, E->getRHS()); return false; } if (!Evaluate(NewVal, this->Info, E->getRHS())) return false; if (Info.getLangOpts().CPlusPlus2a && !HandleUnionActiveMemberChange(Info, E->getLHS(), Result)) return false; return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), NewVal); } //===----------------------------------------------------------------------===// // Pointer Evaluation //===----------------------------------------------------------------------===// /// Attempts to compute the number of bytes available at the pointer /// returned by a function with the alloc_size attribute. Returns true if we /// were successful. Places an unsigned number into `Result`. /// /// This expects the given CallExpr to be a call to a function with an /// alloc_size attribute. static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx, const CallExpr *Call, llvm::APInt &Result) { const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call); assert(AllocSize && AllocSize->getElemSizeParam().isValid()); unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex(); unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType()); if (Call->getNumArgs() <= SizeArgNo) return false; auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) { Expr::EvalResult ExprResult; if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects)) return false; Into = ExprResult.Val.getInt(); if (Into.isNegative() || !Into.isIntN(BitsInSizeT)) return false; Into = Into.zextOrSelf(BitsInSizeT); return true; }; APSInt SizeOfElem; if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem)) return false; if (!AllocSize->getNumElemsParam().isValid()) { Result = std::move(SizeOfElem); return true; } APSInt NumberOfElems; unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex(); if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems)) return false; bool Overflow; llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow); if (Overflow) return false; Result = std::move(BytesAvailable); return true; } /// Convenience function. LVal's base must be a call to an alloc_size /// function. static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx, const LValue &LVal, llvm::APInt &Result) { assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) && "Can't get the size of a non alloc_size function"); const auto *Base = LVal.getLValueBase().get(); const CallExpr *CE = tryUnwrapAllocSizeCall(Base); return getBytesReturnedByAllocSizeCall(Ctx, CE, Result); } /// Attempts to evaluate the given LValueBase as the result of a call to /// a function with the alloc_size attribute. If it was possible to do so, this /// function will return true, make Result's Base point to said function call, /// and mark Result's Base as invalid. static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base, LValue &Result) { if (Base.isNull()) return false; // Because we do no form of static analysis, we only support const variables. // // Additionally, we can't support parameters, nor can we support static // variables (in the latter case, use-before-assign isn't UB; in the former, // we have no clue what they'll be assigned to). const auto *VD = dyn_cast_or_null(Base.dyn_cast()); if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified()) return false; const Expr *Init = VD->getAnyInitializer(); if (!Init) return false; const Expr *E = Init->IgnoreParens(); if (!tryUnwrapAllocSizeCall(E)) return false; // Store E instead of E unwrapped so that the type of the LValue's base is // what the user wanted. Result.setInvalid(E); QualType Pointee = E->getType()->castAs()->getPointeeType(); Result.addUnsizedArray(Info, E, Pointee); return true; } namespace { class PointerExprEvaluator : public ExprEvaluatorBase { LValue &Result; bool InvalidBaseOK; bool Success(const Expr *E) { Result.set(E); return true; } bool evaluateLValue(const Expr *E, LValue &Result) { return EvaluateLValue(E, Result, Info, InvalidBaseOK); } bool evaluatePointer(const Expr *E, LValue &Result) { return EvaluatePointer(E, Result, Info, InvalidBaseOK); } bool visitNonBuiltinCallExpr(const CallExpr *E); public: PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK) : ExprEvaluatorBaseTy(info), Result(Result), InvalidBaseOK(InvalidBaseOK) {} bool Success(const APValue &V, const Expr *E) { Result.setFrom(Info.Ctx, V); return true; } bool ZeroInitialization(const Expr *E) { auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType()); Result.setNull(E->getType(), TargetVal); return true; } bool VisitBinaryOperator(const BinaryOperator *E); bool VisitCastExpr(const CastExpr* E); bool VisitUnaryAddrOf(const UnaryOperator *E); bool VisitObjCStringLiteral(const ObjCStringLiteral *E) { return Success(E); } bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) { if (E->isExpressibleAsConstantInitializer()) return Success(E); if (Info.noteFailure()) EvaluateIgnoredValue(Info, E->getSubExpr()); return Error(E); } bool VisitAddrLabelExpr(const AddrLabelExpr *E) { return Success(E); } bool VisitCallExpr(const CallExpr *E); bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp); bool VisitBlockExpr(const BlockExpr *E) { if (!E->getBlockDecl()->hasCaptures()) return Success(E); return Error(E); } bool VisitCXXThisExpr(const CXXThisExpr *E) { // Can't look at 'this' when checking a potential constant expression. if (Info.checkingPotentialConstantExpression()) return false; if (!Info.CurrentCall->This) { if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit(); else Info.FFDiag(E); return false; } Result = *Info.CurrentCall->This; // If we are inside a lambda's call operator, the 'this' expression refers // to the enclosing '*this' object (either by value or reference) which is // either copied into the closure object's field that represents the '*this' // or refers to '*this'. if (isLambdaCallOperator(Info.CurrentCall->Callee)) { // Update 'Result' to refer to the data member/field of the closure object // that represents the '*this' capture. if (!HandleLValueMember(Info, E, Result, Info.CurrentCall->LambdaThisCaptureField)) return false; // If we captured '*this' by reference, replace the field with its referent. if (Info.CurrentCall->LambdaThisCaptureField->getType() ->isPointerType()) { APValue RVal; if (!handleLValueToRValueConversion(Info, E, E->getType(), Result, RVal)) return false; Result.setFrom(Info.Ctx, RVal); } } return true; } bool VisitSourceLocExpr(const SourceLocExpr *E) { assert(E->isStringType() && "SourceLocExpr isn't a pointer type?"); APValue LValResult = E->EvaluateInContext( Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr()); Result.setFrom(Info.Ctx, LValResult); return true; } // FIXME: Missing: @protocol, @selector }; } // end anonymous namespace static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info, bool InvalidBaseOK) { assert(E->isRValue() && E->getType()->hasPointerRepresentation()); return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E); } bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { if (E->getOpcode() != BO_Add && E->getOpcode() != BO_Sub) return ExprEvaluatorBaseTy::VisitBinaryOperator(E); const Expr *PExp = E->getLHS(); const Expr *IExp = E->getRHS(); if (IExp->getType()->isPointerType()) std::swap(PExp, IExp); bool EvalPtrOK = evaluatePointer(PExp, Result); if (!EvalPtrOK && !Info.noteFailure()) return false; llvm::APSInt Offset; if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) return false; if (E->getOpcode() == BO_Sub) negateAsSigned(Offset); QualType Pointee = PExp->getType()->castAs()->getPointeeType(); return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset); } bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { return evaluateLValue(E->getSubExpr(), Result); } bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) { const Expr *SubExpr = E->getSubExpr(); switch (E->getCastKind()) { default: break; case CK_BitCast: case CK_CPointerToObjCPointerCast: case CK_BlockPointerToObjCPointerCast: case CK_AnyPointerToBlockPointerCast: case CK_AddressSpaceConversion: if (!Visit(SubExpr)) return false; // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are // permitted in constant expressions in C++11. Bitcasts from cv void* are // also static_casts, but we disallow them as a resolution to DR1312. if (!E->getType()->isVoidPointerType()) { Result.Designator.setInvalid(); if (SubExpr->getType()->isVoidPointerType()) CCEDiag(E, diag::note_constexpr_invalid_cast) << 3 << SubExpr->getType(); else CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; } if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr) ZeroInitialization(E); return true; case CK_DerivedToBase: case CK_UncheckedDerivedToBase: if (!evaluatePointer(E->getSubExpr(), Result)) return false; if (!Result.Base && Result.Offset.isZero()) return true; // Now figure out the necessary offset to add to the base LV to get from // the derived class to the base class. return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()-> castAs()->getPointeeType(), Result); case CK_BaseToDerived: if (!Visit(E->getSubExpr())) return false; if (!Result.Base && Result.Offset.isZero()) return true; return HandleBaseToDerivedCast(Info, E, Result); case CK_Dynamic: if (!Visit(E->getSubExpr())) return false; return HandleDynamicCast(Info, cast(E), Result); case CK_NullToPointer: VisitIgnoredValue(E->getSubExpr()); return ZeroInitialization(E); case CK_IntegralToPointer: { CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; APValue Value; if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) break; if (Value.isInt()) { unsigned Size = Info.Ctx.getTypeSize(E->getType()); uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); Result.Base = (Expr*)nullptr; Result.InvalidBase = false; Result.Offset = CharUnits::fromQuantity(N); Result.Designator.setInvalid(); Result.IsNullPtr = false; return true; } else { // Cast is of an lvalue, no need to change value. Result.setFrom(Info.Ctx, Value); return true; } } case CK_ArrayToPointerDecay: { if (SubExpr->isGLValue()) { if (!evaluateLValue(SubExpr, Result)) return false; } else { APValue &Value = createTemporary(SubExpr, false, Result, *Info.CurrentCall); if (!EvaluateInPlace(Value, Info, Result, SubExpr)) return false; } // The result is a pointer to the first element of the array. auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType()); if (auto *CAT = dyn_cast(AT)) Result.addArray(Info, E, CAT); else Result.addUnsizedArray(Info, E, AT->getElementType()); return true; } case CK_FunctionToPointerDecay: return evaluateLValue(SubExpr, Result); case CK_LValueToRValue: { LValue LVal; if (!evaluateLValue(E->getSubExpr(), LVal)) return false; APValue RVal; // Note, we use the subexpression's type in order to retain cv-qualifiers. if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), LVal, RVal)) return InvalidBaseOK && evaluateLValueAsAllocSize(Info, LVal.Base, Result); return Success(RVal, E); } } return ExprEvaluatorBaseTy::VisitCastExpr(E); } static CharUnits GetAlignOfType(EvalInfo &Info, QualType T, UnaryExprOrTypeTrait ExprKind) { // C++ [expr.alignof]p3: // When alignof is applied to a reference type, the result is the // alignment of the referenced type. if (const ReferenceType *Ref = T->getAs()) T = Ref->getPointeeType(); if (T.getQualifiers().hasUnaligned()) return CharUnits::One(); const bool AlignOfReturnsPreferred = Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7; // __alignof is defined to return the preferred alignment. // Before 8, clang returned the preferred alignment for alignof and _Alignof // as well. if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred) return Info.Ctx.toCharUnitsFromBits( Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); // alignof and _Alignof are defined to return the ABI alignment. else if (ExprKind == UETT_AlignOf) return Info.Ctx.getTypeAlignInChars(T.getTypePtr()); else llvm_unreachable("GetAlignOfType on a non-alignment ExprKind"); } static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E, UnaryExprOrTypeTrait ExprKind) { E = E->IgnoreParens(); // The kinds of expressions that we have special-case logic here for // should be kept up to date with the special checks for those // expressions in Sema. // alignof decl is always accepted, even if it doesn't make sense: we default // to 1 in those cases. if (const DeclRefExpr *DRE = dyn_cast(E)) return Info.Ctx.getDeclAlign(DRE->getDecl(), /*RefAsPointee*/true); if (const MemberExpr *ME = dyn_cast(E)) return Info.Ctx.getDeclAlign(ME->getMemberDecl(), /*RefAsPointee*/true); return GetAlignOfType(Info, E->getType(), ExprKind); } // To be clear: this happily visits unsupported builtins. Better name welcomed. bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) { if (ExprEvaluatorBaseTy::VisitCallExpr(E)) return true; if (!(InvalidBaseOK && getAllocSizeAttr(E))) return false; Result.setInvalid(E); QualType PointeeTy = E->getType()->castAs()->getPointeeType(); Result.addUnsizedArray(Info, E, PointeeTy); return true; } bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { if (IsStringLiteralCall(E)) return Success(E); if (unsigned BuiltinOp = E->getBuiltinCallee()) return VisitBuiltinCallExpr(E, BuiltinOp); return visitNonBuiltinCallExpr(E); } bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp) { switch (BuiltinOp) { case Builtin::BI__builtin_addressof: return evaluateLValue(E->getArg(0), Result); case Builtin::BI__builtin_assume_aligned: { // We need to be very careful here because: if the pointer does not have the // asserted alignment, then the behavior is undefined, and undefined // behavior is non-constant. if (!evaluatePointer(E->getArg(0), Result)) return false; LValue OffsetResult(Result); APSInt Alignment; if (!EvaluateInteger(E->getArg(1), Alignment, Info)) return false; CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue()); if (E->getNumArgs() > 2) { APSInt Offset; if (!EvaluateInteger(E->getArg(2), Offset, Info)) return false; int64_t AdditionalOffset = -Offset.getZExtValue(); OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset); } // If there is a base object, then it must have the correct alignment. if (OffsetResult.Base) { CharUnits BaseAlignment; if (const ValueDecl *VD = OffsetResult.Base.dyn_cast()) { BaseAlignment = Info.Ctx.getDeclAlign(VD); } else if (const Expr *E = OffsetResult.Base.dyn_cast()) { BaseAlignment = GetAlignOfExpr(Info, E, UETT_AlignOf); } else { BaseAlignment = GetAlignOfType( Info, OffsetResult.Base.getTypeInfoType(), UETT_AlignOf); } if (BaseAlignment < Align) { Result.Designator.setInvalid(); // FIXME: Add support to Diagnostic for long / long long. CCEDiag(E->getArg(0), diag::note_constexpr_baa_insufficient_alignment) << 0 << (unsigned)BaseAlignment.getQuantity() << (unsigned)Align.getQuantity(); return false; } } // The offset must also have the correct alignment. if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) { Result.Designator.setInvalid(); (OffsetResult.Base ? CCEDiag(E->getArg(0), diag::note_constexpr_baa_insufficient_alignment) << 1 : CCEDiag(E->getArg(0), diag::note_constexpr_baa_value_insufficient_alignment)) << (int)OffsetResult.Offset.getQuantity() << (unsigned)Align.getQuantity(); return false; } return true; } case Builtin::BI__builtin_launder: return evaluatePointer(E->getArg(0), Result); case Builtin::BIstrchr: case Builtin::BIwcschr: case Builtin::BImemchr: case Builtin::BIwmemchr: if (Info.getLangOpts().CPlusPlus11) Info.CCEDiag(E, diag::note_constexpr_invalid_function) << /*isConstexpr*/0 << /*isConstructor*/0 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); else Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); LLVM_FALLTHROUGH; case Builtin::BI__builtin_strchr: case Builtin::BI__builtin_wcschr: case Builtin::BI__builtin_memchr: case Builtin::BI__builtin_char_memchr: case Builtin::BI__builtin_wmemchr: { if (!Visit(E->getArg(0))) return false; APSInt Desired; if (!EvaluateInteger(E->getArg(1), Desired, Info)) return false; uint64_t MaxLength = uint64_t(-1); if (BuiltinOp != Builtin::BIstrchr && BuiltinOp != Builtin::BIwcschr && BuiltinOp != Builtin::BI__builtin_strchr && BuiltinOp != Builtin::BI__builtin_wcschr) { APSInt N; if (!EvaluateInteger(E->getArg(2), N, Info)) return false; MaxLength = N.getExtValue(); } // We cannot find the value if there are no candidates to match against. if (MaxLength == 0u) return ZeroInitialization(E); if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) || Result.Designator.Invalid) return false; QualType CharTy = Result.Designator.getType(Info.Ctx); bool IsRawByte = BuiltinOp == Builtin::BImemchr || BuiltinOp == Builtin::BI__builtin_memchr; assert(IsRawByte || Info.Ctx.hasSameUnqualifiedType( CharTy, E->getArg(0)->getType()->getPointeeType())); // Pointers to const void may point to objects of incomplete type. if (IsRawByte && CharTy->isIncompleteType()) { Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy; return false; } // Give up on byte-oriented matching against multibyte elements. // FIXME: We can compare the bytes in the correct order. if (IsRawByte && Info.Ctx.getTypeSizeInChars(CharTy) != CharUnits::One()) return false; // Figure out what value we're actually looking for (after converting to // the corresponding unsigned type if necessary). uint64_t DesiredVal; bool StopAtNull = false; switch (BuiltinOp) { case Builtin::BIstrchr: case Builtin::BI__builtin_strchr: // strchr compares directly to the passed integer, and therefore // always fails if given an int that is not a char. if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy, E->getArg(1)->getType(), Desired), Desired)) return ZeroInitialization(E); StopAtNull = true; LLVM_FALLTHROUGH; case Builtin::BImemchr: case Builtin::BI__builtin_memchr: case Builtin::BI__builtin_char_memchr: // memchr compares by converting both sides to unsigned char. That's also // correct for strchr if we get this far (to cope with plain char being // unsigned in the strchr case). DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue(); break; case Builtin::BIwcschr: case Builtin::BI__builtin_wcschr: StopAtNull = true; LLVM_FALLTHROUGH; case Builtin::BIwmemchr: case Builtin::BI__builtin_wmemchr: // wcschr and wmemchr are given a wchar_t to look for. Just use it. DesiredVal = Desired.getZExtValue(); break; } for (; MaxLength; --MaxLength) { APValue Char; if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) || !Char.isInt()) return false; if (Char.getInt().getZExtValue() == DesiredVal) return true; if (StopAtNull && !Char.getInt()) break; if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1)) return false; } // Not found: return nullptr. return ZeroInitialization(E); } case Builtin::BImemcpy: case Builtin::BImemmove: case Builtin::BIwmemcpy: case Builtin::BIwmemmove: if (Info.getLangOpts().CPlusPlus11) Info.CCEDiag(E, diag::note_constexpr_invalid_function) << /*isConstexpr*/0 << /*isConstructor*/0 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); else Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); LLVM_FALLTHROUGH; case Builtin::BI__builtin_memcpy: case Builtin::BI__builtin_memmove: case Builtin::BI__builtin_wmemcpy: case Builtin::BI__builtin_wmemmove: { bool WChar = BuiltinOp == Builtin::BIwmemcpy || BuiltinOp == Builtin::BIwmemmove || BuiltinOp == Builtin::BI__builtin_wmemcpy || BuiltinOp == Builtin::BI__builtin_wmemmove; bool Move = BuiltinOp == Builtin::BImemmove || BuiltinOp == Builtin::BIwmemmove || BuiltinOp == Builtin::BI__builtin_memmove || BuiltinOp == Builtin::BI__builtin_wmemmove; // The result of mem* is the first argument. if (!Visit(E->getArg(0))) return false; LValue Dest = Result; LValue Src; if (!EvaluatePointer(E->getArg(1), Src, Info)) return false; APSInt N; if (!EvaluateInteger(E->getArg(2), N, Info)) return false; assert(!N.isSigned() && "memcpy and friends take an unsigned size"); // If the size is zero, we treat this as always being a valid no-op. // (Even if one of the src and dest pointers is null.) if (!N) return true; // Otherwise, if either of the operands is null, we can't proceed. Don't // try to determine the type of the copied objects, because there aren't // any. if (!Src.Base || !Dest.Base) { APValue Val; (!Src.Base ? Src : Dest).moveInto(Val); Info.FFDiag(E, diag::note_constexpr_memcpy_null) << Move << WChar << !!Src.Base << Val.getAsString(Info.Ctx, E->getArg(0)->getType()); return false; } if (Src.Designator.Invalid || Dest.Designator.Invalid) return false; // We require that Src and Dest are both pointers to arrays of // trivially-copyable type. (For the wide version, the designator will be // invalid if the designated object is not a wchar_t.) QualType T = Dest.Designator.getType(Info.Ctx); QualType SrcT = Src.Designator.getType(Info.Ctx); if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) { Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T; return false; } if (T->isIncompleteType()) { Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T; return false; } if (!T.isTriviallyCopyableType(Info.Ctx)) { Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T; return false; } // Figure out how many T's we're copying. uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity(); if (!WChar) { uint64_t Remainder; llvm::APInt OrigN = N; llvm::APInt::udivrem(OrigN, TSize, N, Remainder); if (Remainder) { Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported) << Move << WChar << 0 << T << OrigN.toString(10, /*Signed*/false) << (unsigned)TSize; return false; } } // Check that the copying will remain within the arrays, just so that we // can give a more meaningful diagnostic. This implicitly also checks that // N fits into 64 bits. uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second; uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second; if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) { Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported) << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T << N.toString(10, /*Signed*/false); return false; } uint64_t NElems = N.getZExtValue(); uint64_t NBytes = NElems * TSize; // Check for overlap. int Direction = 1; if (HasSameBase(Src, Dest)) { uint64_t SrcOffset = Src.getLValueOffset().getQuantity(); uint64_t DestOffset = Dest.getLValueOffset().getQuantity(); if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) { // Dest is inside the source region. if (!Move) { Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar; return false; } // For memmove and friends, copy backwards. if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) || !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1)) return false; Direction = -1; } else if (!Move && SrcOffset >= DestOffset && SrcOffset - DestOffset < NBytes) { // Src is inside the destination region for memcpy: invalid. Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar; return false; } } while (true) { APValue Val; if (!handleLValueToRValueConversion(Info, E, T, Src, Val) || !handleAssignment(Info, E, Dest, T, Val)) return false; // Do not iterate past the last element; if we're copying backwards, that // might take us off the start of the array. if (--NElems == 0) return true; if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) || !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction)) return false; } } default: return visitNonBuiltinCallExpr(E); } } //===----------------------------------------------------------------------===// // Member Pointer Evaluation //===----------------------------------------------------------------------===// namespace { class MemberPointerExprEvaluator : public ExprEvaluatorBase { MemberPtr &Result; bool Success(const ValueDecl *D) { Result = MemberPtr(D); return true; } public: MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) : ExprEvaluatorBaseTy(Info), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result.setFrom(V); return true; } bool ZeroInitialization(const Expr *E) { return Success((const ValueDecl*)nullptr); } bool VisitCastExpr(const CastExpr *E); bool VisitUnaryAddrOf(const UnaryOperator *E); }; } // end anonymous namespace static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isMemberPointerType()); return MemberPointerExprEvaluator(Info, Result).Visit(E); } bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_NullToMemberPointer: VisitIgnoredValue(E->getSubExpr()); return ZeroInitialization(E); case CK_BaseToDerivedMemberPointer: { if (!Visit(E->getSubExpr())) return false; if (E->path_empty()) return true; // Base-to-derived member pointer casts store the path in derived-to-base // order, so iterate backwards. The CXXBaseSpecifier also provides us with // the wrong end of the derived->base arc, so stagger the path by one class. typedef std::reverse_iterator ReverseIter; for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); PathI != PathE; ++PathI) { assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); if (!Result.castToDerived(Derived)) return Error(E); } const Type *FinalTy = E->getType()->castAs()->getClass(); if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) return Error(E); return true; } case CK_DerivedToBaseMemberPointer: if (!Visit(E->getSubExpr())) return false; for (CastExpr::path_const_iterator PathI = E->path_begin(), PathE = E->path_end(); PathI != PathE; ++PathI) { assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); if (!Result.castToBase(Base)) return Error(E); } return true; } } bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { // C++11 [expr.unary.op]p3 has very strict rules on how the address of a // member can be formed. return Success(cast(E->getSubExpr())->getDecl()); } //===----------------------------------------------------------------------===// // Record Evaluation //===----------------------------------------------------------------------===// namespace { class RecordExprEvaluator : public ExprEvaluatorBase { const LValue &This; APValue &Result; public: RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result = V; return true; } bool ZeroInitialization(const Expr *E) { return ZeroInitialization(E, E->getType()); } bool ZeroInitialization(const Expr *E, QualType T); bool VisitCallExpr(const CallExpr *E) { return handleCallExpr(E, Result, &This); } bool VisitCastExpr(const CastExpr *E); bool VisitInitListExpr(const InitListExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E) { return VisitCXXConstructExpr(E, E->getType()); } bool VisitLambdaExpr(const LambdaExpr *E); bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T); bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E); bool VisitBinCmp(const BinaryOperator *E); }; } /// Perform zero-initialization on an object of non-union class type. /// C++11 [dcl.init]p5: /// To zero-initialize an object or reference of type T means: /// [...] /// -- if T is a (possibly cv-qualified) non-union class type, /// each non-static data member and each base-class subobject is /// zero-initialized static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, const RecordDecl *RD, const LValue &This, APValue &Result) { assert(!RD->isUnion() && "Expected non-union class type"); const CXXRecordDecl *CD = dyn_cast(RD); Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, std::distance(RD->field_begin(), RD->field_end())); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); if (CD) { unsigned Index = 0; for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), End = CD->bases_end(); I != End; ++I, ++Index) { const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); LValue Subobject = This; if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) return false; if (!HandleClassZeroInitialization(Info, E, Base, Subobject, Result.getStructBase(Index))) return false; } } for (const auto *I : RD->fields()) { // -- if T is a reference type, no initialization is performed. if (I->getType()->isReferenceType()) continue; LValue Subobject = This; if (!HandleLValueMember(Info, E, Subobject, I, &Layout)) return false; ImplicitValueInitExpr VIE(I->getType()); if (!EvaluateInPlace( Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) return false; } return true; } bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) { const RecordDecl *RD = T->castAs()->getDecl(); if (RD->isInvalidDecl()) return false; if (RD->isUnion()) { // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the // object's first non-static named data member is zero-initialized RecordDecl::field_iterator I = RD->field_begin(); if (I == RD->field_end()) { Result = APValue((const FieldDecl*)nullptr); return true; } LValue Subobject = This; if (!HandleLValueMember(Info, E, Subobject, *I)) return false; Result = APValue(*I); ImplicitValueInitExpr VIE(I->getType()); return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); } if (isa(RD) && cast(RD)->getNumVBases()) { Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD; return false; } return HandleClassZeroInitialization(Info, E, RD, This, Result); } bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_ConstructorConversion: return Visit(E->getSubExpr()); case CK_DerivedToBase: case CK_UncheckedDerivedToBase: { APValue DerivedObject; if (!Evaluate(DerivedObject, Info, E->getSubExpr())) return false; if (!DerivedObject.isStruct()) return Error(E->getSubExpr()); // Derived-to-base rvalue conversion: just slice off the derived part. APValue *Value = &DerivedObject; const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); for (CastExpr::path_const_iterator PathI = E->path_begin(), PathE = E->path_end(); PathI != PathE; ++PathI) { assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); Value = &Value->getStructBase(getBaseIndex(RD, Base)); RD = Base; } Result = *Value; return true; } } } bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { if (E->isTransparent()) return Visit(E->getInit(0)); const RecordDecl *RD = E->getType()->castAs()->getDecl(); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); auto *CXXRD = dyn_cast(RD); EvalInfo::EvaluatingConstructorRAII EvalObj( Info, ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries}, CXXRD && CXXRD->getNumBases()); if (RD->isUnion()) { const FieldDecl *Field = E->getInitializedFieldInUnion(); Result = APValue(Field); if (!Field) return true; // If the initializer list for a union does not contain any elements, the // first element of the union is value-initialized. // FIXME: The element should be initialized from an initializer list. // Is this difference ever observable for initializer lists which // we don't build? ImplicitValueInitExpr VIE(Field->getType()); const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; LValue Subobject = This; if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) return false; // Temporarily override This, in case there's a CXXDefaultInitExpr in here. ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, isa(InitExpr)); return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); } if (!Result.hasValue()) Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0, std::distance(RD->field_begin(), RD->field_end())); unsigned ElementNo = 0; bool Success = true; // Initialize base classes. if (CXXRD && CXXRD->getNumBases()) { for (const auto &Base : CXXRD->bases()) { assert(ElementNo < E->getNumInits() && "missing init for base class"); const Expr *Init = E->getInit(ElementNo); LValue Subobject = This; if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base)) return false; APValue &FieldVal = Result.getStructBase(ElementNo); if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) { if (!Info.noteFailure()) return false; Success = false; } ++ElementNo; } EvalObj.finishedConstructingBases(); } // Initialize members. for (const auto *Field : RD->fields()) { // Anonymous bit-fields are not considered members of the class for // purposes of aggregate initialization. if (Field->isUnnamedBitfield()) continue; LValue Subobject = This; bool HaveInit = ElementNo < E->getNumInits(); // FIXME: Diagnostics here should point to the end of the initializer // list, not the start. if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, Subobject, Field, &Layout)) return false; // Perform an implicit value-initialization for members beyond the end of // the initializer list. ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE; // Temporarily override This, in case there's a CXXDefaultInitExpr in here. ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, isa(Init)); APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) || (Field->isBitField() && !truncateBitfieldValue(Info, Init, FieldVal, Field))) { if (!Info.noteFailure()) return false; Success = false; } } return Success; } bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T) { // Note that E's type is not necessarily the type of our class here; we might // be initializing an array element instead. const CXXConstructorDecl *FD = E->getConstructor(); if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; bool ZeroInit = E->requiresZeroInitialization(); if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { // If we've already performed zero-initialization, we're already done. if (Result.hasValue()) return true; // We can get here in two different ways: // 1) We're performing value-initialization, and should zero-initialize // the object, or // 2) We're performing default-initialization of an object with a trivial // constexpr default constructor, in which case we should start the // lifetimes of all the base subobjects (there can be no data member // subobjects in this case) per [basic.life]p1. // Either way, ZeroInitialization is appropriate. return ZeroInitialization(E, T); } const FunctionDecl *Definition = nullptr; auto Body = FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) return false; // Avoid materializing a temporary for an elidable copy/move constructor. if (E->isElidable() && !ZeroInit) if (const MaterializeTemporaryExpr *ME = dyn_cast(E->getArg(0))) return Visit(ME->GetTemporaryExpr()); if (ZeroInit && !ZeroInitialization(E, T)) return false; auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); return HandleConstructorCall(E, This, Args, cast(Definition), Info, Result); } bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr( const CXXInheritedCtorInitExpr *E) { if (!Info.CurrentCall) { assert(Info.checkingPotentialConstantExpression()); return false; } const CXXConstructorDecl *FD = E->getConstructor(); if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; const FunctionDecl *Definition = nullptr; auto Body = FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) return false; return HandleConstructorCall(E, This, Info.CurrentCall->Arguments, cast(Definition), Info, Result); } bool RecordExprEvaluator::VisitCXXStdInitializerListExpr( const CXXStdInitializerListExpr *E) { const ConstantArrayType *ArrayType = Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); LValue Array; if (!EvaluateLValue(E->getSubExpr(), Array, Info)) return false; // Get a pointer to the first element of the array. Array.addArray(Info, E, ArrayType); // FIXME: Perform the checks on the field types in SemaInit. RecordDecl *Record = E->getType()->castAs()->getDecl(); RecordDecl::field_iterator Field = Record->field_begin(); if (Field == Record->field_end()) return Error(E); // Start pointer. if (!Field->getType()->isPointerType() || !Info.Ctx.hasSameType(Field->getType()->getPointeeType(), ArrayType->getElementType())) return Error(E); // FIXME: What if the initializer_list type has base classes, etc? Result = APValue(APValue::UninitStruct(), 0, 2); Array.moveInto(Result.getStructField(0)); if (++Field == Record->field_end()) return Error(E); if (Field->getType()->isPointerType() && Info.Ctx.hasSameType(Field->getType()->getPointeeType(), ArrayType->getElementType())) { // End pointer. if (!HandleLValueArrayAdjustment(Info, E, Array, ArrayType->getElementType(), ArrayType->getSize().getZExtValue())) return false; Array.moveInto(Result.getStructField(1)); } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) // Length. Result.getStructField(1) = APValue(APSInt(ArrayType->getSize())); else return Error(E); if (++Field != Record->field_end()) return Error(E); return true; } bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) { const CXXRecordDecl *ClosureClass = E->getLambdaClass(); if (ClosureClass->isInvalidDecl()) return false; if (Info.checkingPotentialConstantExpression()) return true; const size_t NumFields = std::distance(ClosureClass->field_begin(), ClosureClass->field_end()); assert(NumFields == (size_t)std::distance(E->capture_init_begin(), E->capture_init_end()) && "The number of lambda capture initializers should equal the number of " "fields within the closure type"); Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields); // Iterate through all the lambda's closure object's fields and initialize // them. auto *CaptureInitIt = E->capture_init_begin(); const LambdaCapture *CaptureIt = ClosureClass->captures_begin(); bool Success = true; for (const auto *Field : ClosureClass->fields()) { assert(CaptureInitIt != E->capture_init_end()); // Get the initializer for this field Expr *const CurFieldInit = *CaptureInitIt++; // If there is no initializer, either this is a VLA or an error has // occurred. if (!CurFieldInit) return Error(E); APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); if (!EvaluateInPlace(FieldVal, Info, This, CurFieldInit)) { if (!Info.keepEvaluatingAfterFailure()) return false; Success = false; } ++CaptureIt; } return Success; } static bool EvaluateRecord(const Expr *E, const LValue &This, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isRecordType() && "can't evaluate expression as a record rvalue"); return RecordExprEvaluator(Info, This, Result).Visit(E); } //===----------------------------------------------------------------------===// // Temporary Evaluation // // Temporaries are represented in the AST as rvalues, but generally behave like // lvalues. The full-object of which the temporary is a subobject is implicitly // materialized so that a reference can bind to it. //===----------------------------------------------------------------------===// namespace { class TemporaryExprEvaluator : public LValueExprEvaluatorBase { public: TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : LValueExprEvaluatorBaseTy(Info, Result, false) {} /// Visit an expression which constructs the value of this temporary. bool VisitConstructExpr(const Expr *E) { APValue &Value = createTemporary(E, false, Result, *Info.CurrentCall); return EvaluateInPlace(Value, Info, Result, E); } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return LValueExprEvaluatorBaseTy::VisitCastExpr(E); case CK_ConstructorConversion: return VisitConstructExpr(E->getSubExpr()); } } bool VisitInitListExpr(const InitListExpr *E) { return VisitConstructExpr(E); } bool VisitCXXConstructExpr(const CXXConstructExpr *E) { return VisitConstructExpr(E); } bool VisitCallExpr(const CallExpr *E) { return VisitConstructExpr(E); } bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) { return VisitConstructExpr(E); } bool VisitLambdaExpr(const LambdaExpr *E) { return VisitConstructExpr(E); } }; } // end anonymous namespace /// Evaluate an expression of record type as a temporary. static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isRecordType()); return TemporaryExprEvaluator(Info, Result).Visit(E); } //===----------------------------------------------------------------------===// // Vector Evaluation //===----------------------------------------------------------------------===// namespace { class VectorExprEvaluator : public ExprEvaluatorBase { APValue &Result; public: VectorExprEvaluator(EvalInfo &info, APValue &Result) : ExprEvaluatorBaseTy(info), Result(Result) {} bool Success(ArrayRef V, const Expr *E) { assert(V.size() == E->getType()->castAs()->getNumElements()); // FIXME: remove this APValue copy. Result = APValue(V.data(), V.size()); return true; } bool Success(const APValue &V, const Expr *E) { assert(V.isVector()); Result = V; return true; } bool ZeroInitialization(const Expr *E); bool VisitUnaryReal(const UnaryOperator *E) { return Visit(E->getSubExpr()); } bool VisitCastExpr(const CastExpr* E); bool VisitInitListExpr(const InitListExpr *E); bool VisitUnaryImag(const UnaryOperator *E); // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div, // binary comparisons, binary and/or/xor, // shufflevector, ExtVectorElementExpr }; } // end anonymous namespace static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue"); return VectorExprEvaluator(Info, Result).Visit(E); } bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) { const VectorType *VTy = E->getType()->castAs(); unsigned NElts = VTy->getNumElements(); const Expr *SE = E->getSubExpr(); QualType SETy = SE->getType(); switch (E->getCastKind()) { case CK_VectorSplat: { APValue Val = APValue(); if (SETy->isIntegerType()) { APSInt IntResult; if (!EvaluateInteger(SE, IntResult, Info)) return false; Val = APValue(std::move(IntResult)); } else if (SETy->isRealFloatingType()) { APFloat FloatResult(0.0); if (!EvaluateFloat(SE, FloatResult, Info)) return false; Val = APValue(std::move(FloatResult)); } else { return Error(E); } // Splat and create vector APValue. SmallVector Elts(NElts, Val); return Success(Elts, E); } case CK_BitCast: { // Evaluate the operand into an APInt we can extract from. llvm::APInt SValInt; if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) return false; // Extract the elements QualType EltTy = VTy->getElementType(); unsigned EltSize = Info.Ctx.getTypeSize(EltTy); bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); SmallVector Elts; if (EltTy->isRealFloatingType()) { const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); unsigned FloatEltSize = EltSize; if (&Sem == &APFloat::x87DoubleExtended()) FloatEltSize = 80; for (unsigned i = 0; i < NElts; i++) { llvm::APInt Elt; if (BigEndian) Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); else Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); Elts.push_back(APValue(APFloat(Sem, Elt))); } } else if (EltTy->isIntegerType()) { for (unsigned i = 0; i < NElts; i++) { llvm::APInt Elt; if (BigEndian) Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); else Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType()))); } } else { return Error(E); } return Success(Elts, E); } default: return ExprEvaluatorBaseTy::VisitCastExpr(E); } } bool VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { const VectorType *VT = E->getType()->castAs(); unsigned NumInits = E->getNumInits(); unsigned NumElements = VT->getNumElements(); QualType EltTy = VT->getElementType(); SmallVector Elements; // The number of initializers can be less than the number of // vector elements. For OpenCL, this can be due to nested vector // initialization. For GCC compatibility, missing trailing elements // should be initialized with zeroes. unsigned CountInits = 0, CountElts = 0; while (CountElts < NumElements) { // Handle nested vector initialization. if (CountInits < NumInits && E->getInit(CountInits)->getType()->isVectorType()) { APValue v; if (!EvaluateVector(E->getInit(CountInits), v, Info)) return Error(E); unsigned vlen = v.getVectorLength(); for (unsigned j = 0; j < vlen; j++) Elements.push_back(v.getVectorElt(j)); CountElts += vlen; } else if (EltTy->isIntegerType()) { llvm::APSInt sInt(32); if (CountInits < NumInits) { if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) return false; } else // trailing integer zero. sInt = Info.Ctx.MakeIntValue(0, EltTy); Elements.push_back(APValue(sInt)); CountElts++; } else { llvm::APFloat f(0.0); if (CountInits < NumInits) { if (!EvaluateFloat(E->getInit(CountInits), f, Info)) return false; } else // trailing float zero. f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); Elements.push_back(APValue(f)); CountElts++; } CountInits++; } return Success(Elements, E); } bool VectorExprEvaluator::ZeroInitialization(const Expr *E) { const VectorType *VT = E->getType()->getAs(); QualType EltTy = VT->getElementType(); APValue ZeroElement; if (EltTy->isIntegerType()) ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); else ZeroElement = APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); SmallVector Elements(VT->getNumElements(), ZeroElement); return Success(Elements, E); } bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { VisitIgnoredValue(E->getSubExpr()); return ZeroInitialization(E); } //===----------------------------------------------------------------------===// // Array Evaluation //===----------------------------------------------------------------------===// namespace { class ArrayExprEvaluator : public ExprEvaluatorBase { const LValue &This; APValue &Result; public: ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} bool Success(const APValue &V, const Expr *E) { assert(V.isArray() && "expected array"); Result = V; return true; } bool ZeroInitialization(const Expr *E) { const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); if (!CAT) return Error(E); Result = APValue(APValue::UninitArray(), 0, CAT->getSize().getZExtValue()); if (!Result.hasArrayFiller()) return true; // Zero-initialize all elements. LValue Subobject = This; Subobject.addArray(Info, E, CAT); ImplicitValueInitExpr VIE(CAT->getElementType()); return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); } bool VisitCallExpr(const CallExpr *E) { return handleCallExpr(E, Result, &This); } bool VisitInitListExpr(const InitListExpr *E); bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E, const LValue &Subobject, APValue *Value, QualType Type); bool VisitStringLiteral(const StringLiteral *E) { expandStringLiteral(Info, E, Result); return true; } }; } // end anonymous namespace static bool EvaluateArray(const Expr *E, const LValue &This, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue"); return ArrayExprEvaluator(Info, This, Result).Visit(E); } // Return true iff the given array filler may depend on the element index. static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) { // For now, just whitelist non-class value-initialization and initialization // lists comprised of them. if (isa(FillerExpr)) return false; if (const InitListExpr *ILE = dyn_cast(FillerExpr)) { for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) { if (MaybeElementDependentArrayFiller(ILE->getInit(I))) return true; } return false; } return true; } bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) { const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); if (!CAT) return Error(E); // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] // an appropriately-typed string literal enclosed in braces. if (E->isStringLiteralInit()) return Visit(E->getInit(0)); bool Success = true; assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && "zero-initialized array shouldn't have any initialized elts"); APValue Filler; if (Result.isArray() && Result.hasArrayFiller()) Filler = Result.getArrayFiller(); unsigned NumEltsToInit = E->getNumInits(); unsigned NumElts = CAT->getSize().getZExtValue(); const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr; // If the initializer might depend on the array index, run it for each // array element. if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(FillerExpr)) NumEltsToInit = NumElts; LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: " << NumEltsToInit << ".\n"); Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts); // If the array was previously zero-initialized, preserve the // zero-initialized values. if (Filler.hasValue()) { for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) Result.getArrayInitializedElt(I) = Filler; if (Result.hasArrayFiller()) Result.getArrayFiller() = Filler; } LValue Subobject = This; Subobject.addArray(Info, E, CAT); for (unsigned Index = 0; Index != NumEltsToInit; ++Index) { const Expr *Init = Index < E->getNumInits() ? E->getInit(Index) : FillerExpr; if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), Info, Subobject, Init) || !HandleLValueArrayAdjustment(Info, Init, Subobject, CAT->getElementType(), 1)) { if (!Info.noteFailure()) return false; Success = false; } } if (!Result.hasArrayFiller()) return Success; // If we get here, we have a trivial filler, which we can just evaluate // once and splat over the rest of the array elements. assert(FillerExpr && "no array filler for incomplete init list"); return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, FillerExpr) && Success; } bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) { if (E->getCommonExpr() && !Evaluate(Info.CurrentCall->createTemporary(E->getCommonExpr(), false), Info, E->getCommonExpr()->getSourceExpr())) return false; auto *CAT = cast(E->getType()->castAsArrayTypeUnsafe()); uint64_t Elements = CAT->getSize().getZExtValue(); Result = APValue(APValue::UninitArray(), Elements, Elements); LValue Subobject = This; Subobject.addArray(Info, E, CAT); bool Success = true; for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) { if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), Info, Subobject, E->getSubExpr()) || !HandleLValueArrayAdjustment(Info, E, Subobject, CAT->getElementType(), 1)) { if (!Info.noteFailure()) return false; Success = false; } } return Success; } bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { return VisitCXXConstructExpr(E, This, &Result, E->getType()); } bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, const LValue &Subobject, APValue *Value, QualType Type) { bool HadZeroInit = Value->hasValue(); if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) { unsigned N = CAT->getSize().getZExtValue(); // Preserve the array filler if we had prior zero-initialization. APValue Filler = HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller() : APValue(); *Value = APValue(APValue::UninitArray(), N, N); if (HadZeroInit) for (unsigned I = 0; I != N; ++I) Value->getArrayInitializedElt(I) = Filler; // Initialize the elements. LValue ArrayElt = Subobject; ArrayElt.addArray(Info, E, CAT); for (unsigned I = 0; I != N; ++I) if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I), CAT->getElementType()) || !HandleLValueArrayAdjustment(Info, E, ArrayElt, CAT->getElementType(), 1)) return false; return true; } if (!Type->isRecordType()) return Error(E); return RecordExprEvaluator(Info, Subobject, *Value) .VisitCXXConstructExpr(E, Type); } //===----------------------------------------------------------------------===// // Integer Evaluation // // As a GNU extension, we support casting pointers to sufficiently-wide integer // types and back in constant folding. Integer values are thus represented // either as an integer-valued APValue, or as an lvalue-valued APValue. //===----------------------------------------------------------------------===// namespace { class IntExprEvaluator : public ExprEvaluatorBase { APValue &Result; public: IntExprEvaluator(EvalInfo &info, APValue &result) : ExprEvaluatorBaseTy(info), Result(result) {} bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { assert(E->getType()->isIntegralOrEnumerationType() && "Invalid evaluation result."); assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && "Invalid evaluation result."); assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && "Invalid evaluation result."); Result = APValue(SI); return true; } bool Success(const llvm::APSInt &SI, const Expr *E) { return Success(SI, E, Result); } bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { assert(E->getType()->isIntegralOrEnumerationType() && "Invalid evaluation result."); assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && "Invalid evaluation result."); Result = APValue(APSInt(I)); Result.getInt().setIsUnsigned( E->getType()->isUnsignedIntegerOrEnumerationType()); return true; } bool Success(const llvm::APInt &I, const Expr *E) { return Success(I, E, Result); } bool Success(uint64_t Value, const Expr *E, APValue &Result) { assert(E->getType()->isIntegralOrEnumerationType() && "Invalid evaluation result."); Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); return true; } bool Success(uint64_t Value, const Expr *E) { return Success(Value, E, Result); } bool Success(CharUnits Size, const Expr *E) { return Success(Size.getQuantity(), E); } bool Success(const APValue &V, const Expr *E) { if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) { Result = V; return true; } return Success(V.getInt(), E); } bool ZeroInitialization(const Expr *E) { return Success(0, E); } //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// bool VisitConstantExpr(const ConstantExpr *E); bool VisitIntegerLiteral(const IntegerLiteral *E) { return Success(E->getValue(), E); } bool VisitCharacterLiteral(const CharacterLiteral *E) { return Success(E->getValue(), E); } bool CheckReferencedDecl(const Expr *E, const Decl *D); bool VisitDeclRefExpr(const DeclRefExpr *E) { if (CheckReferencedDecl(E, E->getDecl())) return true; return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); } bool VisitMemberExpr(const MemberExpr *E) { if (CheckReferencedDecl(E, E->getMemberDecl())) { VisitIgnoredBaseExpression(E->getBase()); return true; } return ExprEvaluatorBaseTy::VisitMemberExpr(E); } bool VisitCallExpr(const CallExpr *E); bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp); bool VisitBinaryOperator(const BinaryOperator *E); bool VisitOffsetOfExpr(const OffsetOfExpr *E); bool VisitUnaryOperator(const UnaryOperator *E); bool VisitCastExpr(const CastExpr* E); bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { return Success(E->getValue(), E); } bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { return Success(E->getValue(), E); } bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) { if (Info.ArrayInitIndex == uint64_t(-1)) { // We were asked to evaluate this subexpression independent of the // enclosing ArrayInitLoopExpr. We can't do that. Info.FFDiag(E); return false; } return Success(Info.ArrayInitIndex, E); } // Note, GNU defines __null as an integer, not a pointer. bool VisitGNUNullExpr(const GNUNullExpr *E) { return ZeroInitialization(E); } bool VisitTypeTraitExpr(const TypeTraitExpr *E) { return Success(E->getValue(), E); } bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { return Success(E->getValue(), E); } bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { return Success(E->getValue(), E); } bool VisitUnaryReal(const UnaryOperator *E); bool VisitUnaryImag(const UnaryOperator *E); bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); bool VisitSourceLocExpr(const SourceLocExpr *E); // FIXME: Missing: array subscript of vector, member of vector }; class FixedPointExprEvaluator : public ExprEvaluatorBase { APValue &Result; public: FixedPointExprEvaluator(EvalInfo &info, APValue &result) : ExprEvaluatorBaseTy(info), Result(result) {} bool Success(const llvm::APInt &I, const Expr *E) { return Success( APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E); } bool Success(uint64_t Value, const Expr *E) { return Success( APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E); } bool Success(const APValue &V, const Expr *E) { return Success(V.getFixedPoint(), E); } bool Success(const APFixedPoint &V, const Expr *E) { assert(E->getType()->isFixedPointType() && "Invalid evaluation result."); assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) && "Invalid evaluation result."); Result = APValue(V); return true; } //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// bool VisitFixedPointLiteral(const FixedPointLiteral *E) { return Success(E->getValue(), E); } bool VisitCastExpr(const CastExpr *E); bool VisitUnaryOperator(const UnaryOperator *E); bool VisitBinaryOperator(const BinaryOperator *E); }; } // end anonymous namespace /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and /// produce either the integer value or a pointer. /// /// GCC has a heinous extension which folds casts between pointer types and /// pointer-sized integral types. We support this by allowing the evaluation of /// an integer rvalue to produce a pointer (represented as an lvalue) instead. /// Some simple arithmetic on such values is supported (they are treated much /// like char*). static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType()); return IntExprEvaluator(Info, Result).Visit(E); } static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { APValue Val; if (!EvaluateIntegerOrLValue(E, Val, Info)) return false; if (!Val.isInt()) { // FIXME: It would be better to produce the diagnostic for casting // a pointer to an integer. Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } Result = Val.getInt(); return true; } bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) { APValue Evaluated = E->EvaluateInContext( Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr()); return Success(Evaluated, E); } static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result, EvalInfo &Info) { if (E->getType()->isFixedPointType()) { APValue Val; if (!FixedPointExprEvaluator(Info, Val).Visit(E)) return false; if (!Val.isFixedPoint()) return false; Result = Val.getFixedPoint(); return true; } return false; } static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result, EvalInfo &Info) { if (E->getType()->isIntegerType()) { auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType()); APSInt Val; if (!EvaluateInteger(E, Val, Info)) return false; Result = APFixedPoint(Val, FXSema); return true; } else if (E->getType()->isFixedPointType()) { return EvaluateFixedPoint(E, Result, Info); } return false; } /// Check whether the given declaration can be directly converted to an integral /// rvalue. If not, no diagnostic is produced; there are other things we can /// try. bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { // Enums are integer constant exprs. if (const EnumConstantDecl *ECD = dyn_cast(D)) { // Check for signedness/width mismatches between E type and ECD value. bool SameSign = (ECD->getInitVal().isSigned() == E->getType()->isSignedIntegerOrEnumerationType()); bool SameWidth = (ECD->getInitVal().getBitWidth() == Info.Ctx.getIntWidth(E->getType())); if (SameSign && SameWidth) return Success(ECD->getInitVal(), E); else { // Get rid of mismatch (otherwise Success assertions will fail) // by computing a new value matching the type of E. llvm::APSInt Val = ECD->getInitVal(); if (!SameSign) Val.setIsSigned(!ECD->getInitVal().isSigned()); if (!SameWidth) Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); return Success(Val, E); } } return false; } /// Values returned by __builtin_classify_type, chosen to match the values /// produced by GCC's builtin. enum class GCCTypeClass { None = -1, Void = 0, Integer = 1, // GCC reserves 2 for character types, but instead classifies them as // integers. Enum = 3, Bool = 4, Pointer = 5, // GCC reserves 6 for references, but appears to never use it (because // expressions never have reference type, presumably). PointerToDataMember = 7, RealFloat = 8, Complex = 9, // GCC reserves 10 for functions, but does not use it since GCC version 6 due // to decay to pointer. (Prior to version 6 it was only used in C++ mode). // GCC claims to reserve 11 for pointers to member functions, but *actually* // uses 12 for that purpose, same as for a class or struct. Maybe it // internally implements a pointer to member as a struct? Who knows. PointerToMemberFunction = 12, // Not a bug, see above. ClassOrStruct = 12, Union = 13, // GCC reserves 14 for arrays, but does not use it since GCC version 6 due to // decay to pointer. (Prior to version 6 it was only used in C++ mode). // GCC reserves 15 for strings, but actually uses 5 (pointer) for string // literals. }; /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way /// as GCC. static GCCTypeClass EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) { assert(!T->isDependentType() && "unexpected dependent type"); QualType CanTy = T.getCanonicalType(); const BuiltinType *BT = dyn_cast(CanTy); switch (CanTy->getTypeClass()) { #define TYPE(ID, BASE) #define DEPENDENT_TYPE(ID, BASE) case Type::ID: #define NON_CANONICAL_TYPE(ID, BASE) case Type::ID: #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID: #include "clang/AST/TypeNodes.def" case Type::Auto: case Type::DeducedTemplateSpecialization: llvm_unreachable("unexpected non-canonical or dependent type"); case Type::Builtin: switch (BT->getKind()) { #define BUILTIN_TYPE(ID, SINGLETON_ID) #define SIGNED_TYPE(ID, SINGLETON_ID) \ case BuiltinType::ID: return GCCTypeClass::Integer; #define FLOATING_TYPE(ID, SINGLETON_ID) \ case BuiltinType::ID: return GCCTypeClass::RealFloat; #define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \ case BuiltinType::ID: break; #include "clang/AST/BuiltinTypes.def" case BuiltinType::Void: return GCCTypeClass::Void; case BuiltinType::Bool: return GCCTypeClass::Bool; case BuiltinType::Char_U: case BuiltinType::UChar: case BuiltinType::WChar_U: case BuiltinType::Char8: case BuiltinType::Char16: case BuiltinType::Char32: case BuiltinType::UShort: case BuiltinType::UInt: case BuiltinType::ULong: case BuiltinType::ULongLong: case BuiltinType::UInt128: return GCCTypeClass::Integer; case BuiltinType::UShortAccum: case BuiltinType::UAccum: case BuiltinType::ULongAccum: case BuiltinType::UShortFract: case BuiltinType::UFract: case BuiltinType::ULongFract: case BuiltinType::SatUShortAccum: case BuiltinType::SatUAccum: case BuiltinType::SatULongAccum: case BuiltinType::SatUShortFract: case BuiltinType::SatUFract: case BuiltinType::SatULongFract: return GCCTypeClass::None; case BuiltinType::NullPtr: case BuiltinType::ObjCId: case BuiltinType::ObjCClass: case BuiltinType::ObjCSel: #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \ case BuiltinType::Id: #include "clang/Basic/OpenCLImageTypes.def" #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \ case BuiltinType::Id: #include "clang/Basic/OpenCLExtensionTypes.def" case BuiltinType::OCLSampler: case BuiltinType::OCLEvent: case BuiltinType::OCLClkEvent: case BuiltinType::OCLQueue: case BuiltinType::OCLReserveID: return GCCTypeClass::None; case BuiltinType::Dependent: llvm_unreachable("unexpected dependent type"); }; llvm_unreachable("unexpected placeholder type"); case Type::Enum: return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer; case Type::Pointer: case Type::ConstantArray: case Type::VariableArray: case Type::IncompleteArray: case Type::FunctionNoProto: case Type::FunctionProto: return GCCTypeClass::Pointer; case Type::MemberPointer: return CanTy->isMemberDataPointerType() ? GCCTypeClass::PointerToDataMember : GCCTypeClass::PointerToMemberFunction; case Type::Complex: return GCCTypeClass::Complex; case Type::Record: return CanTy->isUnionType() ? GCCTypeClass::Union : GCCTypeClass::ClassOrStruct; case Type::Atomic: // GCC classifies _Atomic T the same as T. return EvaluateBuiltinClassifyType( CanTy->castAs()->getValueType(), LangOpts); case Type::BlockPointer: case Type::Vector: case Type::ExtVector: case Type::ObjCObject: case Type::ObjCInterface: case Type::ObjCObjectPointer: case Type::Pipe: // GCC classifies vectors as None. We follow its lead and classify all // other types that don't fit into the regular classification the same way. return GCCTypeClass::None; case Type::LValueReference: case Type::RValueReference: llvm_unreachable("invalid type for expression"); } llvm_unreachable("unexpected type class"); } /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way /// as GCC. static GCCTypeClass EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) { // If no argument was supplied, default to None. This isn't // ideal, however it is what gcc does. if (E->getNumArgs() == 0) return GCCTypeClass::None; // FIXME: Bizarrely, GCC treats a call with more than one argument as not // being an ICE, but still folds it to a constant using the type of the first // argument. return EvaluateBuiltinClassifyType(E->getArg(0)->getType(), LangOpts); } /// EvaluateBuiltinConstantPForLValue - Determine the result of /// __builtin_constant_p when applied to the given pointer. /// /// A pointer is only "constant" if it is null (or a pointer cast to integer) /// or it points to the first character of a string literal. static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) { APValue::LValueBase Base = LV.getLValueBase(); if (Base.isNull()) { // A null base is acceptable. return true; } else if (const Expr *E = Base.dyn_cast()) { if (!isa(E)) return false; return LV.getLValueOffset().isZero(); } else if (Base.is()) { // Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to // evaluate to true. return true; } else { // Any other base is not constant enough for GCC. return false; } } /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to /// GCC as we can manage. static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) { // This evaluation is not permitted to have side-effects, so evaluate it in // a speculative evaluation context. SpeculativeEvaluationRAII SpeculativeEval(Info); // Constant-folding is always enabled for the operand of __builtin_constant_p // (even when the enclosing evaluation context otherwise requires a strict // language-specific constant expression). FoldConstant Fold(Info, true); QualType ArgType = Arg->getType(); // __builtin_constant_p always has one operand. The rules which gcc follows // are not precisely documented, but are as follows: // // - If the operand is of integral, floating, complex or enumeration type, // and can be folded to a known value of that type, it returns 1. // - If the operand can be folded to a pointer to the first character // of a string literal (or such a pointer cast to an integral type) // or to a null pointer or an integer cast to a pointer, it returns 1. // // Otherwise, it returns 0. // // FIXME: GCC also intends to return 1 for literals of aggregate types, but // its support for this did not work prior to GCC 9 and is not yet well // understood. if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() || ArgType->isAnyComplexType() || ArgType->isPointerType() || ArgType->isNullPtrType()) { APValue V; if (!::EvaluateAsRValue(Info, Arg, V)) { Fold.keepDiagnostics(); return false; } // For a pointer (possibly cast to integer), there are special rules. if (V.getKind() == APValue::LValue) return EvaluateBuiltinConstantPForLValue(V); // Otherwise, any constant value is good enough. return V.hasValue(); } // Anything else isn't considered to be sufficiently constant. return false; } /// Retrieves the "underlying object type" of the given expression, /// as used by __builtin_object_size. static QualType getObjectType(APValue::LValueBase B) { if (const ValueDecl *D = B.dyn_cast()) { if (const VarDecl *VD = dyn_cast(D)) return VD->getType(); } else if (const Expr *E = B.get()) { if (isa(E)) return E->getType(); } else if (B.is()) { return B.getTypeInfoType(); } return QualType(); } /// A more selective version of E->IgnoreParenCasts for /// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only /// to change the type of E. /// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo` /// /// Always returns an RValue with a pointer representation. static const Expr *ignorePointerCastsAndParens(const Expr *E) { assert(E->isRValue() && E->getType()->hasPointerRepresentation()); auto *NoParens = E->IgnoreParens(); auto *Cast = dyn_cast(NoParens); if (Cast == nullptr) return NoParens; // We only conservatively allow a few kinds of casts, because this code is // inherently a simple solution that seeks to support the common case. auto CastKind = Cast->getCastKind(); if (CastKind != CK_NoOp && CastKind != CK_BitCast && CastKind != CK_AddressSpaceConversion) return NoParens; auto *SubExpr = Cast->getSubExpr(); if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isRValue()) return NoParens; return ignorePointerCastsAndParens(SubExpr); } /// Checks to see if the given LValue's Designator is at the end of the LValue's /// record layout. e.g. /// struct { struct { int a, b; } fst, snd; } obj; /// obj.fst // no /// obj.snd // yes /// obj.fst.a // no /// obj.fst.b // no /// obj.snd.a // no /// obj.snd.b // yes /// /// Please note: this function is specialized for how __builtin_object_size /// views "objects". /// /// If this encounters an invalid RecordDecl or otherwise cannot determine the /// correct result, it will always return true. static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) { assert(!LVal.Designator.Invalid); auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) { const RecordDecl *Parent = FD->getParent(); Invalid = Parent->isInvalidDecl(); if (Invalid || Parent->isUnion()) return true; const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent); return FD->getFieldIndex() + 1 == Layout.getFieldCount(); }; auto &Base = LVal.getLValueBase(); if (auto *ME = dyn_cast_or_null(Base.dyn_cast())) { if (auto *FD = dyn_cast(ME->getMemberDecl())) { bool Invalid; if (!IsLastOrInvalidFieldDecl(FD, Invalid)) return Invalid; } else if (auto *IFD = dyn_cast(ME->getMemberDecl())) { for (auto *FD : IFD->chain()) { bool Invalid; if (!IsLastOrInvalidFieldDecl(cast(FD), Invalid)) return Invalid; } } } unsigned I = 0; QualType BaseType = getType(Base); if (LVal.Designator.FirstEntryIsAnUnsizedArray) { // If we don't know the array bound, conservatively assume we're looking at // the final array element. ++I; if (BaseType->isIncompleteArrayType()) BaseType = Ctx.getAsArrayType(BaseType)->getElementType(); else BaseType = BaseType->castAs()->getPointeeType(); } for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) { const auto &Entry = LVal.Designator.Entries[I]; if (BaseType->isArrayType()) { // Because __builtin_object_size treats arrays as objects, we can ignore // the index iff this is the last array in the Designator. if (I + 1 == E) return true; const auto *CAT = cast(Ctx.getAsArrayType(BaseType)); uint64_t Index = Entry.getAsArrayIndex(); if (Index + 1 != CAT->getSize()) return false; BaseType = CAT->getElementType(); } else if (BaseType->isAnyComplexType()) { const auto *CT = BaseType->castAs(); uint64_t Index = Entry.getAsArrayIndex(); if (Index != 1) return false; BaseType = CT->getElementType(); } else if (auto *FD = getAsField(Entry)) { bool Invalid; if (!IsLastOrInvalidFieldDecl(FD, Invalid)) return Invalid; BaseType = FD->getType(); } else { assert(getAsBaseClass(Entry) && "Expecting cast to a base class"); return false; } } return true; } /// Tests to see if the LValue has a user-specified designator (that isn't /// necessarily valid). Note that this always returns 'true' if the LValue has /// an unsized array as its first designator entry, because there's currently no /// way to tell if the user typed *foo or foo[0]. static bool refersToCompleteObject(const LValue &LVal) { if (LVal.Designator.Invalid) return false; if (!LVal.Designator.Entries.empty()) return LVal.Designator.isMostDerivedAnUnsizedArray(); if (!LVal.InvalidBase) return true; // If `E` is a MemberExpr, then the first part of the designator is hiding in // the LValueBase. const auto *E = LVal.Base.dyn_cast(); return !E || !isa(E); } /// Attempts to detect a user writing into a piece of memory that's impossible /// to figure out the size of by just using types. static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) { const SubobjectDesignator &Designator = LVal.Designator; // Notes: // - Users can only write off of the end when we have an invalid base. Invalid // bases imply we don't know where the memory came from. // - We used to be a bit more aggressive here; we'd only be conservative if // the array at the end was flexible, or if it had 0 or 1 elements. This // broke some common standard library extensions (PR30346), but was // otherwise seemingly fine. It may be useful to reintroduce this behavior // with some sort of whitelist. OTOH, it seems that GCC is always // conservative with the last element in structs (if it's an array), so our // current behavior is more compatible than a whitelisting approach would // be. return LVal.InvalidBase && Designator.Entries.size() == Designator.MostDerivedPathLength && Designator.MostDerivedIsArrayElement && isDesignatorAtObjectEnd(Ctx, LVal); } /// Converts the given APInt to CharUnits, assuming the APInt is unsigned. /// Fails if the conversion would cause loss of precision. static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int, CharUnits &Result) { auto CharUnitsMax = std::numeric_limits::max(); if (Int.ugt(CharUnitsMax)) return false; Result = CharUnits::fromQuantity(Int.getZExtValue()); return true; } /// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will /// determine how many bytes exist from the beginning of the object to either /// the end of the current subobject, or the end of the object itself, depending /// on what the LValue looks like + the value of Type. /// /// If this returns false, the value of Result is undefined. static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc, unsigned Type, const LValue &LVal, CharUnits &EndOffset) { bool DetermineForCompleteObject = refersToCompleteObject(LVal); auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) { if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType()) return false; return HandleSizeof(Info, ExprLoc, Ty, Result); }; // We want to evaluate the size of the entire object. This is a valid fallback // for when Type=1 and the designator is invalid, because we're asked for an // upper-bound. if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) { // Type=3 wants a lower bound, so we can't fall back to this. if (Type == 3 && !DetermineForCompleteObject) return false; llvm::APInt APEndOffset; if (isBaseAnAllocSizeCall(LVal.getLValueBase()) && getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset)) return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset); if (LVal.InvalidBase) return false; QualType BaseTy = getObjectType(LVal.getLValueBase()); return CheckedHandleSizeof(BaseTy, EndOffset); } // We want to evaluate the size of a subobject. const SubobjectDesignator &Designator = LVal.Designator; // The following is a moderately common idiom in C: // // struct Foo { int a; char c[1]; }; // struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar)); // strcpy(&F->c[0], Bar); // // In order to not break too much legacy code, we need to support it. if (isUserWritingOffTheEnd(Info.Ctx, LVal)) { // If we can resolve this to an alloc_size call, we can hand that back, // because we know for certain how many bytes there are to write to. llvm::APInt APEndOffset; if (isBaseAnAllocSizeCall(LVal.getLValueBase()) && getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset)) return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset); // If we cannot determine the size of the initial allocation, then we can't // given an accurate upper-bound. However, we are still able to give // conservative lower-bounds for Type=3. if (Type == 1) return false; } CharUnits BytesPerElem; if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem)) return false; // According to the GCC documentation, we want the size of the subobject // denoted by the pointer. But that's not quite right -- what we actually // want is the size of the immediately-enclosing array, if there is one. int64_t ElemsRemaining; if (Designator.MostDerivedIsArrayElement && Designator.Entries.size() == Designator.MostDerivedPathLength) { uint64_t ArraySize = Designator.getMostDerivedArraySize(); uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex(); ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex; } else { ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1; } EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining; return true; } /// Tries to evaluate the __builtin_object_size for @p E. If successful, /// returns true and stores the result in @p Size. /// /// If @p WasError is non-null, this will report whether the failure to evaluate /// is to be treated as an Error in IntExprEvaluator. static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type, EvalInfo &Info, uint64_t &Size) { // Determine the denoted object. LValue LVal; { // The operand of __builtin_object_size is never evaluated for side-effects. // If there are any, but we can determine the pointed-to object anyway, then // ignore the side-effects. SpeculativeEvaluationRAII SpeculativeEval(Info); IgnoreSideEffectsRAII Fold(Info); if (E->isGLValue()) { // It's possible for us to be given GLValues if we're called via // Expr::tryEvaluateObjectSize. APValue RVal; if (!EvaluateAsRValue(Info, E, RVal)) return false; LVal.setFrom(Info.Ctx, RVal); } else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info, /*InvalidBaseOK=*/true)) return false; } // If we point to before the start of the object, there are no accessible // bytes. if (LVal.getLValueOffset().isNegative()) { Size = 0; return true; } CharUnits EndOffset; if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset)) return false; // If we've fallen outside of the end offset, just pretend there's nothing to // write to/read from. if (EndOffset <= LVal.getLValueOffset()) Size = 0; else Size = (EndOffset - LVal.getLValueOffset()).getQuantity(); return true; } bool IntExprEvaluator::VisitConstantExpr(const ConstantExpr *E) { llvm::SaveAndRestore InConstantContext(Info.InConstantContext, true); if (E->getResultAPValueKind() != APValue::None) return Success(E->getAPValueResult(), E); return ExprEvaluatorBaseTy::VisitConstantExpr(E); } bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { if (unsigned BuiltinOp = E->getBuiltinCallee()) return VisitBuiltinCallExpr(E, BuiltinOp); return ExprEvaluatorBaseTy::VisitCallExpr(E); } bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp) { switch (unsigned BuiltinOp = E->getBuiltinCallee()) { default: return ExprEvaluatorBaseTy::VisitCallExpr(E); case Builtin::BI__builtin_dynamic_object_size: case Builtin::BI__builtin_object_size: { // The type was checked when we built the expression. unsigned Type = E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); assert(Type <= 3 && "unexpected type"); uint64_t Size; if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size)) return Success(Size, E); if (E->getArg(0)->HasSideEffects(Info.Ctx)) return Success((Type & 2) ? 0 : -1, E); // Expression had no side effects, but we couldn't statically determine the // size of the referenced object. switch (Info.EvalMode) { case EvalInfo::EM_ConstantExpression: case EvalInfo::EM_ConstantFold: case EvalInfo::EM_IgnoreSideEffects: // Leave it to IR generation. return Error(E); case EvalInfo::EM_ConstantExpressionUnevaluated: // Reduce it to a constant now. return Success((Type & 2) ? 0 : -1, E); } llvm_unreachable("unexpected EvalMode"); } case Builtin::BI__builtin_os_log_format_buffer_size: { analyze_os_log::OSLogBufferLayout Layout; analyze_os_log::computeOSLogBufferLayout(Info.Ctx, E, Layout); return Success(Layout.size().getQuantity(), E); } case Builtin::BI__builtin_bswap16: case Builtin::BI__builtin_bswap32: case Builtin::BI__builtin_bswap64: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; return Success(Val.byteSwap(), E); } case Builtin::BI__builtin_classify_type: return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E); case Builtin::BI__builtin_clrsb: case Builtin::BI__builtin_clrsbl: case Builtin::BI__builtin_clrsbll: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; return Success(Val.getBitWidth() - Val.getMinSignedBits(), E); } case Builtin::BI__builtin_clz: case Builtin::BI__builtin_clzl: case Builtin::BI__builtin_clzll: case Builtin::BI__builtin_clzs: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; if (!Val) return Error(E); return Success(Val.countLeadingZeros(), E); } case Builtin::BI__builtin_constant_p: { const Expr *Arg = E->getArg(0); if (EvaluateBuiltinConstantP(Info, Arg)) return Success(true, E); if (Info.InConstantContext || Arg->HasSideEffects(Info.Ctx)) { // Outside a constant context, eagerly evaluate to false in the presence // of side-effects in order to avoid -Wunsequenced false-positives in // a branch on __builtin_constant_p(expr). return Success(false, E); } Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } case Builtin::BI__builtin_is_constant_evaluated: return Success(Info.InConstantContext, E); case Builtin::BI__builtin_ctz: case Builtin::BI__builtin_ctzl: case Builtin::BI__builtin_ctzll: case Builtin::BI__builtin_ctzs: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; if (!Val) return Error(E); return Success(Val.countTrailingZeros(), E); } case Builtin::BI__builtin_eh_return_data_regno: { int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); return Success(Operand, E); } case Builtin::BI__builtin_expect: return Visit(E->getArg(0)); case Builtin::BI__builtin_ffs: case Builtin::BI__builtin_ffsl: case Builtin::BI__builtin_ffsll: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; unsigned N = Val.countTrailingZeros(); return Success(N == Val.getBitWidth() ? 0 : N + 1, E); } case Builtin::BI__builtin_fpclassify: { APFloat Val(0.0); if (!EvaluateFloat(E->getArg(5), Val, Info)) return false; unsigned Arg; switch (Val.getCategory()) { case APFloat::fcNaN: Arg = 0; break; case APFloat::fcInfinity: Arg = 1; break; case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break; case APFloat::fcZero: Arg = 4; break; } return Visit(E->getArg(Arg)); } case Builtin::BI__builtin_isinf_sign: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E); } case Builtin::BI__builtin_isinf: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isInfinity() ? 1 : 0, E); } case Builtin::BI__builtin_isfinite: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isFinite() ? 1 : 0, E); } case Builtin::BI__builtin_isnan: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isNaN() ? 1 : 0, E); } case Builtin::BI__builtin_isnormal: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isNormal() ? 1 : 0, E); } case Builtin::BI__builtin_parity: case Builtin::BI__builtin_parityl: case Builtin::BI__builtin_parityll: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; return Success(Val.countPopulation() % 2, E); } case Builtin::BI__builtin_popcount: case Builtin::BI__builtin_popcountl: case Builtin::BI__builtin_popcountll: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; return Success(Val.countPopulation(), E); } case Builtin::BIstrlen: case Builtin::BIwcslen: // A call to strlen is not a constant expression. if (Info.getLangOpts().CPlusPlus11) Info.CCEDiag(E, diag::note_constexpr_invalid_function) << /*isConstexpr*/0 << /*isConstructor*/0 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); else Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); LLVM_FALLTHROUGH; case Builtin::BI__builtin_strlen: case Builtin::BI__builtin_wcslen: { // As an extension, we support __builtin_strlen() as a constant expression, // and support folding strlen() to a constant. LValue String; if (!EvaluatePointer(E->getArg(0), String, Info)) return false; QualType CharTy = E->getArg(0)->getType()->getPointeeType(); // Fast path: if it's a string literal, search the string value. if (const StringLiteral *S = dyn_cast_or_null( String.getLValueBase().dyn_cast())) { // The string literal may have embedded null characters. Find the first // one and truncate there. StringRef Str = S->getBytes(); int64_t Off = String.Offset.getQuantity(); if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() && S->getCharByteWidth() == 1 && // FIXME: Add fast-path for wchar_t too. Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) { Str = Str.substr(Off); StringRef::size_type Pos = Str.find(0); if (Pos != StringRef::npos) Str = Str.substr(0, Pos); return Success(Str.size(), E); } // Fall through to slow path to issue appropriate diagnostic. } // Slow path: scan the bytes of the string looking for the terminating 0. for (uint64_t Strlen = 0; /**/; ++Strlen) { APValue Char; if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) || !Char.isInt()) return false; if (!Char.getInt()) return Success(Strlen, E); if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1)) return false; } } case Builtin::BIstrcmp: case Builtin::BIwcscmp: case Builtin::BIstrncmp: case Builtin::BIwcsncmp: case Builtin::BImemcmp: case Builtin::BIbcmp: case Builtin::BIwmemcmp: // A call to strlen is not a constant expression. if (Info.getLangOpts().CPlusPlus11) Info.CCEDiag(E, diag::note_constexpr_invalid_function) << /*isConstexpr*/0 << /*isConstructor*/0 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); else Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); LLVM_FALLTHROUGH; case Builtin::BI__builtin_strcmp: case Builtin::BI__builtin_wcscmp: case Builtin::BI__builtin_strncmp: case Builtin::BI__builtin_wcsncmp: case Builtin::BI__builtin_memcmp: case Builtin::BI__builtin_bcmp: case Builtin::BI__builtin_wmemcmp: { LValue String1, String2; if (!EvaluatePointer(E->getArg(0), String1, Info) || !EvaluatePointer(E->getArg(1), String2, Info)) return false; uint64_t MaxLength = uint64_t(-1); if (BuiltinOp != Builtin::BIstrcmp && BuiltinOp != Builtin::BIwcscmp && BuiltinOp != Builtin::BI__builtin_strcmp && BuiltinOp != Builtin::BI__builtin_wcscmp) { APSInt N; if (!EvaluateInteger(E->getArg(2), N, Info)) return false; MaxLength = N.getExtValue(); } // Empty substrings compare equal by definition. if (MaxLength == 0u) return Success(0, E); if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) || !String2.checkNullPointerForFoldAccess(Info, E, AK_Read) || String1.Designator.Invalid || String2.Designator.Invalid) return false; QualType CharTy1 = String1.Designator.getType(Info.Ctx); QualType CharTy2 = String2.Designator.getType(Info.Ctx); bool IsRawByte = BuiltinOp == Builtin::BImemcmp || BuiltinOp == Builtin::BIbcmp || BuiltinOp == Builtin::BI__builtin_memcmp || BuiltinOp == Builtin::BI__builtin_bcmp; assert(IsRawByte || (Info.Ctx.hasSameUnqualifiedType( CharTy1, E->getArg(0)->getType()->getPointeeType()) && Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2))); const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) { return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) && handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) && Char1.isInt() && Char2.isInt(); }; const auto &AdvanceElems = [&] { return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) && HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1); }; if (IsRawByte) { uint64_t BytesRemaining = MaxLength; // Pointers to const void may point to objects of incomplete type. if (CharTy1->isIncompleteType()) { Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy1; return false; } if (CharTy2->isIncompleteType()) { Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy2; return false; } uint64_t CharTy1Width{Info.Ctx.getTypeSize(CharTy1)}; CharUnits CharTy1Size = Info.Ctx.toCharUnitsFromBits(CharTy1Width); // Give up on comparing between elements with disparate widths. if (CharTy1Size != Info.Ctx.getTypeSizeInChars(CharTy2)) return false; uint64_t BytesPerElement = CharTy1Size.getQuantity(); assert(BytesRemaining && "BytesRemaining should not be zero: the " "following loop considers at least one element"); while (true) { APValue Char1, Char2; if (!ReadCurElems(Char1, Char2)) return false; // We have compatible in-memory widths, but a possible type and // (for `bool`) internal representation mismatch. // Assuming two's complement representation, including 0 for `false` and // 1 for `true`, we can check an appropriate number of elements for // equality even if they are not byte-sized. APSInt Char1InMem = Char1.getInt().extOrTrunc(CharTy1Width); APSInt Char2InMem = Char2.getInt().extOrTrunc(CharTy1Width); if (Char1InMem.ne(Char2InMem)) { // If the elements are byte-sized, then we can produce a three-way // comparison result in a straightforward manner. if (BytesPerElement == 1u) { // memcmp always compares unsigned chars. return Success(Char1InMem.ult(Char2InMem) ? -1 : 1, E); } // The result is byte-order sensitive, and we have multibyte elements. // FIXME: We can compare the remaining bytes in the correct order. return false; } if (!AdvanceElems()) return false; if (BytesRemaining <= BytesPerElement) break; BytesRemaining -= BytesPerElement; } // Enough elements are equal to account for the memcmp limit. return Success(0, E); } bool StopAtNull = (BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp && BuiltinOp != Builtin::BIwmemcmp && BuiltinOp != Builtin::BI__builtin_memcmp && BuiltinOp != Builtin::BI__builtin_bcmp && BuiltinOp != Builtin::BI__builtin_wmemcmp); bool IsWide = BuiltinOp == Builtin::BIwcscmp || BuiltinOp == Builtin::BIwcsncmp || BuiltinOp == Builtin::BIwmemcmp || BuiltinOp == Builtin::BI__builtin_wcscmp || BuiltinOp == Builtin::BI__builtin_wcsncmp || BuiltinOp == Builtin::BI__builtin_wmemcmp; for (; MaxLength; --MaxLength) { APValue Char1, Char2; if (!ReadCurElems(Char1, Char2)) return false; if (Char1.getInt() != Char2.getInt()) { if (IsWide) // wmemcmp compares with wchar_t signedness. return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E); // memcmp always compares unsigned chars. return Success(Char1.getInt().ult(Char2.getInt()) ? -1 : 1, E); } if (StopAtNull && !Char1.getInt()) return Success(0, E); assert(!(StopAtNull && !Char2.getInt())); if (!AdvanceElems()) return false; } // We hit the strncmp / memcmp limit. return Success(0, E); } case Builtin::BI__atomic_always_lock_free: case Builtin::BI__atomic_is_lock_free: case Builtin::BI__c11_atomic_is_lock_free: { APSInt SizeVal; if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) return false; // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power // of two less than the maximum inline atomic width, we know it is // lock-free. If the size isn't a power of two, or greater than the // maximum alignment where we promote atomics, we know it is not lock-free // (at least not in the sense of atomic_is_lock_free). Otherwise, // the answer can only be determined at runtime; for example, 16-byte // atomics have lock-free implementations on some, but not all, // x86-64 processors. // Check power-of-two. CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); if (Size.isPowerOfTwo()) { // Check against inlining width. unsigned InlineWidthBits = Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || Size == CharUnits::One() || E->getArg(1)->isNullPointerConstant(Info.Ctx, Expr::NPC_NeverValueDependent)) // OK, we will inline appropriately-aligned operations of this size, // and _Atomic(T) is appropriately-aligned. return Success(1, E); QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> castAs()->getPointeeType(); if (!PointeeType->isIncompleteType() && Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { // OK, we will inline operations on this object. return Success(1, E); } } } // Avoid emiting call for runtime decision on PowerPC 32-bit // The lock free possibilities on this platform are covered by the lines // above and we know in advance other cases require lock if (Info.Ctx.getTargetInfo().getTriple().getArch() == llvm::Triple::ppc) { return Success(0, E); } return BuiltinOp == Builtin::BI__atomic_always_lock_free ? Success(0, E) : Error(E); } case Builtin::BIomp_is_initial_device: // We can decide statically which value the runtime would return if called. return Success(Info.getLangOpts().OpenMPIsDevice ? 0 : 1, E); case Builtin::BI__builtin_add_overflow: case Builtin::BI__builtin_sub_overflow: case Builtin::BI__builtin_mul_overflow: case Builtin::BI__builtin_sadd_overflow: case Builtin::BI__builtin_uadd_overflow: case Builtin::BI__builtin_uaddl_overflow: case Builtin::BI__builtin_uaddll_overflow: case Builtin::BI__builtin_usub_overflow: case Builtin::BI__builtin_usubl_overflow: case Builtin::BI__builtin_usubll_overflow: case Builtin::BI__builtin_umul_overflow: case Builtin::BI__builtin_umull_overflow: case Builtin::BI__builtin_umulll_overflow: case Builtin::BI__builtin_saddl_overflow: case Builtin::BI__builtin_saddll_overflow: case Builtin::BI__builtin_ssub_overflow: case Builtin::BI__builtin_ssubl_overflow: case Builtin::BI__builtin_ssubll_overflow: case Builtin::BI__builtin_smul_overflow: case Builtin::BI__builtin_smull_overflow: case Builtin::BI__builtin_smulll_overflow: { LValue ResultLValue; APSInt LHS, RHS; QualType ResultType = E->getArg(2)->getType()->getPointeeType(); if (!EvaluateInteger(E->getArg(0), LHS, Info) || !EvaluateInteger(E->getArg(1), RHS, Info) || !EvaluatePointer(E->getArg(2), ResultLValue, Info)) return false; APSInt Result; bool DidOverflow = false; // If the types don't have to match, enlarge all 3 to the largest of them. if (BuiltinOp == Builtin::BI__builtin_add_overflow || BuiltinOp == Builtin::BI__builtin_sub_overflow || BuiltinOp == Builtin::BI__builtin_mul_overflow) { bool IsSigned = LHS.isSigned() || RHS.isSigned() || ResultType->isSignedIntegerOrEnumerationType(); bool AllSigned = LHS.isSigned() && RHS.isSigned() && ResultType->isSignedIntegerOrEnumerationType(); uint64_t LHSSize = LHS.getBitWidth(); uint64_t RHSSize = RHS.getBitWidth(); uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType); uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize); // Add an additional bit if the signedness isn't uniformly agreed to. We // could do this ONLY if there is a signed and an unsigned that both have // MaxBits, but the code to check that is pretty nasty. The issue will be // caught in the shrink-to-result later anyway. if (IsSigned && !AllSigned) ++MaxBits; LHS = APSInt(LHS.extOrTrunc(MaxBits), !IsSigned); RHS = APSInt(RHS.extOrTrunc(MaxBits), !IsSigned); Result = APSInt(MaxBits, !IsSigned); } // Find largest int. switch (BuiltinOp) { default: llvm_unreachable("Invalid value for BuiltinOp"); case Builtin::BI__builtin_add_overflow: case Builtin::BI__builtin_sadd_overflow: case Builtin::BI__builtin_saddl_overflow: case Builtin::BI__builtin_saddll_overflow: case Builtin::BI__builtin_uadd_overflow: case Builtin::BI__builtin_uaddl_overflow: case Builtin::BI__builtin_uaddll_overflow: Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow) : LHS.uadd_ov(RHS, DidOverflow); break; case Builtin::BI__builtin_sub_overflow: case Builtin::BI__builtin_ssub_overflow: case Builtin::BI__builtin_ssubl_overflow: case Builtin::BI__builtin_ssubll_overflow: case Builtin::BI__builtin_usub_overflow: case Builtin::BI__builtin_usubl_overflow: case Builtin::BI__builtin_usubll_overflow: Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow) : LHS.usub_ov(RHS, DidOverflow); break; case Builtin::BI__builtin_mul_overflow: case Builtin::BI__builtin_smul_overflow: case Builtin::BI__builtin_smull_overflow: case Builtin::BI__builtin_smulll_overflow: case Builtin::BI__builtin_umul_overflow: case Builtin::BI__builtin_umull_overflow: case Builtin::BI__builtin_umulll_overflow: Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow) : LHS.umul_ov(RHS, DidOverflow); break; } // In the case where multiple sizes are allowed, truncate and see if // the values are the same. if (BuiltinOp == Builtin::BI__builtin_add_overflow || BuiltinOp == Builtin::BI__builtin_sub_overflow || BuiltinOp == Builtin::BI__builtin_mul_overflow) { // APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead, // since it will give us the behavior of a TruncOrSelf in the case where // its parameter <= its size. We previously set Result to be at least the // type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth // will work exactly like TruncOrSelf. APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType)); Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType()); if (!APSInt::isSameValue(Temp, Result)) DidOverflow = true; Result = Temp; } APValue APV{Result}; if (!handleAssignment(Info, E, ResultLValue, ResultType, APV)) return false; return Success(DidOverflow, E); } } } /// Determine whether this is a pointer past the end of the complete /// object referred to by the lvalue. static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx, const LValue &LV) { // A null pointer can be viewed as being "past the end" but we don't // choose to look at it that way here. if (!LV.getLValueBase()) return false; // If the designator is valid and refers to a subobject, we're not pointing // past the end. if (!LV.getLValueDesignator().Invalid && !LV.getLValueDesignator().isOnePastTheEnd()) return false; // A pointer to an incomplete type might be past-the-end if the type's size is // zero. We cannot tell because the type is incomplete. QualType Ty = getType(LV.getLValueBase()); if (Ty->isIncompleteType()) return true; // We're a past-the-end pointer if we point to the byte after the object, // no matter what our type or path is. auto Size = Ctx.getTypeSizeInChars(Ty); return LV.getLValueOffset() == Size; } namespace { /// Data recursive integer evaluator of certain binary operators. /// /// We use a data recursive algorithm for binary operators so that we are able /// to handle extreme cases of chained binary operators without causing stack /// overflow. class DataRecursiveIntBinOpEvaluator { struct EvalResult { APValue Val; bool Failed; EvalResult() : Failed(false) { } void swap(EvalResult &RHS) { Val.swap(RHS.Val); Failed = RHS.Failed; RHS.Failed = false; } }; struct Job { const Expr *E; EvalResult LHSResult; // meaningful only for binary operator expression. enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; Job() = default; Job(Job &&) = default; void startSpeculativeEval(EvalInfo &Info) { SpecEvalRAII = SpeculativeEvaluationRAII(Info); } private: SpeculativeEvaluationRAII SpecEvalRAII; }; SmallVector Queue; IntExprEvaluator &IntEval; EvalInfo &Info; APValue &FinalResult; public: DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } /// True if \param E is a binary operator that we are going to handle /// data recursively. /// We handle binary operators that are comma, logical, or that have operands /// with integral or enumeration type. static bool shouldEnqueue(const BinaryOperator *E) { return E->getOpcode() == BO_Comma || E->isLogicalOp() || (E->isRValue() && E->getType()->isIntegralOrEnumerationType() && E->getLHS()->getType()->isIntegralOrEnumerationType() && E->getRHS()->getType()->isIntegralOrEnumerationType()); } bool Traverse(const BinaryOperator *E) { enqueue(E); EvalResult PrevResult; while (!Queue.empty()) process(PrevResult); if (PrevResult.Failed) return false; FinalResult.swap(PrevResult.Val); return true; } private: bool Success(uint64_t Value, const Expr *E, APValue &Result) { return IntEval.Success(Value, E, Result); } bool Success(const APSInt &Value, const Expr *E, APValue &Result) { return IntEval.Success(Value, E, Result); } bool Error(const Expr *E) { return IntEval.Error(E); } bool Error(const Expr *E, diag::kind D) { return IntEval.Error(E, D); } OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { return Info.CCEDiag(E, D); } // Returns true if visiting the RHS is necessary, false otherwise. bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, bool &SuppressRHSDiags); bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, const BinaryOperator *E, APValue &Result); void EvaluateExpr(const Expr *E, EvalResult &Result) { Result.Failed = !Evaluate(Result.Val, Info, E); if (Result.Failed) Result.Val = APValue(); } void process(EvalResult &Result); void enqueue(const Expr *E) { E = E->IgnoreParens(); Queue.resize(Queue.size()+1); Queue.back().E = E; Queue.back().Kind = Job::AnyExprKind; } }; } bool DataRecursiveIntBinOpEvaluator:: VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, bool &SuppressRHSDiags) { if (E->getOpcode() == BO_Comma) { // Ignore LHS but note if we could not evaluate it. if (LHSResult.Failed) return Info.noteSideEffect(); return true; } if (E->isLogicalOp()) { bool LHSAsBool; if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) { // We were able to evaluate the LHS, see if we can get away with not // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 if (LHSAsBool == (E->getOpcode() == BO_LOr)) { Success(LHSAsBool, E, LHSResult.Val); return false; // Ignore RHS } } else { LHSResult.Failed = true; // Since we weren't able to evaluate the left hand side, it // might have had side effects. if (!Info.noteSideEffect()) return false; // We can't evaluate the LHS; however, sometimes the result // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. // Don't ignore RHS and suppress diagnostics from this arm. SuppressRHSDiags = true; } return true; } assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && E->getRHS()->getType()->isIntegralOrEnumerationType()); if (LHSResult.Failed && !Info.noteFailure()) return false; // Ignore RHS; return true; } static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index, bool IsSub) { // Compute the new offset in the appropriate width, wrapping at 64 bits. // FIXME: When compiling for a 32-bit target, we should use 32-bit // offsets. assert(!LVal.hasLValuePath() && "have designator for integer lvalue"); CharUnits &Offset = LVal.getLValueOffset(); uint64_t Offset64 = Offset.getQuantity(); uint64_t Index64 = Index.extOrTrunc(64).getZExtValue(); Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64 : Offset64 + Index64); } bool DataRecursiveIntBinOpEvaluator:: VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, const BinaryOperator *E, APValue &Result) { if (E->getOpcode() == BO_Comma) { if (RHSResult.Failed) return false; Result = RHSResult.Val; return true; } if (E->isLogicalOp()) { bool lhsResult, rhsResult; bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); if (LHSIsOK) { if (RHSIsOK) { if (E->getOpcode() == BO_LOr) return Success(lhsResult || rhsResult, E, Result); else return Success(lhsResult && rhsResult, E, Result); } } else { if (RHSIsOK) { // We can't evaluate the LHS; however, sometimes the result // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. if (rhsResult == (E->getOpcode() == BO_LOr)) return Success(rhsResult, E, Result); } } return false; } assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && E->getRHS()->getType()->isIntegralOrEnumerationType()); if (LHSResult.Failed || RHSResult.Failed) return false; const APValue &LHSVal = LHSResult.Val; const APValue &RHSVal = RHSResult.Val; // Handle cases like (unsigned long)&a + 4. if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { Result = LHSVal; addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub); return true; } // Handle cases like 4 + (unsigned long)&a if (E->getOpcode() == BO_Add && RHSVal.isLValue() && LHSVal.isInt()) { Result = RHSVal; addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false); return true; } if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { // Handle (intptr_t)&&A - (intptr_t)&&B. if (!LHSVal.getLValueOffset().isZero() || !RHSVal.getLValueOffset().isZero()) return false; const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast(); const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast(); if (!LHSExpr || !RHSExpr) return false; const AddrLabelExpr *LHSAddrExpr = dyn_cast(LHSExpr); const AddrLabelExpr *RHSAddrExpr = dyn_cast(RHSExpr); if (!LHSAddrExpr || !RHSAddrExpr) return false; // Make sure both labels come from the same function. if (LHSAddrExpr->getLabel()->getDeclContext() != RHSAddrExpr->getLabel()->getDeclContext()) return false; Result = APValue(LHSAddrExpr, RHSAddrExpr); return true; } // All the remaining cases expect both operands to be an integer if (!LHSVal.isInt() || !RHSVal.isInt()) return Error(E); // Set up the width and signedness manually, in case it can't be deduced // from the operation we're performing. // FIXME: Don't do this in the cases where we can deduce it. APSInt Value(Info.Ctx.getIntWidth(E->getType()), E->getType()->isUnsignedIntegerOrEnumerationType()); if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(), RHSVal.getInt(), Value)) return false; return Success(Value, E, Result); } void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { Job &job = Queue.back(); switch (job.Kind) { case Job::AnyExprKind: { if (const BinaryOperator *Bop = dyn_cast(job.E)) { if (shouldEnqueue(Bop)) { job.Kind = Job::BinOpKind; enqueue(Bop->getLHS()); return; } } EvaluateExpr(job.E, Result); Queue.pop_back(); return; } case Job::BinOpKind: { const BinaryOperator *Bop = cast(job.E); bool SuppressRHSDiags = false; if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { Queue.pop_back(); return; } if (SuppressRHSDiags) job.startSpeculativeEval(Info); job.LHSResult.swap(Result); job.Kind = Job::BinOpVisitedLHSKind; enqueue(Bop->getRHS()); return; } case Job::BinOpVisitedLHSKind: { const BinaryOperator *Bop = cast(job.E); EvalResult RHS; RHS.swap(Result); Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); Queue.pop_back(); return; } } llvm_unreachable("Invalid Job::Kind!"); } namespace { /// Used when we determine that we should fail, but can keep evaluating prior to /// noting that we had a failure. class DelayedNoteFailureRAII { EvalInfo &Info; bool NoteFailure; public: DelayedNoteFailureRAII(EvalInfo &Info, bool NoteFailure = true) : Info(Info), NoteFailure(NoteFailure) {} ~DelayedNoteFailureRAII() { if (NoteFailure) { bool ContinueAfterFailure = Info.noteFailure(); (void)ContinueAfterFailure; assert(ContinueAfterFailure && "Shouldn't have kept evaluating on failure."); } } }; } template static bool EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E, SuccessCB &&Success, AfterCB &&DoAfter) { assert(E->isComparisonOp() && "expected comparison operator"); assert((E->getOpcode() == BO_Cmp || E->getType()->isIntegralOrEnumerationType()) && "unsupported binary expression evaluation"); auto Error = [&](const Expr *E) { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; }; using CCR = ComparisonCategoryResult; bool IsRelational = E->isRelationalOp(); bool IsEquality = E->isEqualityOp(); if (E->getOpcode() == BO_Cmp) { const ComparisonCategoryInfo &CmpInfo = Info.Ctx.CompCategories.getInfoForType(E->getType()); IsRelational = CmpInfo.isOrdered(); IsEquality = CmpInfo.isEquality(); } QualType LHSTy = E->getLHS()->getType(); QualType RHSTy = E->getRHS()->getType(); if (LHSTy->isIntegralOrEnumerationType() && RHSTy->isIntegralOrEnumerationType()) { APSInt LHS, RHS; bool LHSOK = EvaluateInteger(E->getLHS(), LHS, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluateInteger(E->getRHS(), RHS, Info) || !LHSOK) return false; if (LHS < RHS) return Success(CCR::Less, E); if (LHS > RHS) return Success(CCR::Greater, E); return Success(CCR::Equal, E); } if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) { APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHSTy)); APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHSTy)); bool LHSOK = EvaluateFixedPointOrInteger(E->getLHS(), LHSFX, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluateFixedPointOrInteger(E->getRHS(), RHSFX, Info) || !LHSOK) return false; if (LHSFX < RHSFX) return Success(CCR::Less, E); if (LHSFX > RHSFX) return Success(CCR::Greater, E); return Success(CCR::Equal, E); } if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) { ComplexValue LHS, RHS; bool LHSOK; if (E->isAssignmentOp()) { LValue LV; EvaluateLValue(E->getLHS(), LV, Info); LHSOK = false; } else if (LHSTy->isRealFloatingType()) { LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info); if (LHSOK) { LHS.makeComplexFloat(); LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics()); } } else { LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); } if (!LHSOK && !Info.noteFailure()) return false; if (E->getRHS()->getType()->isRealFloatingType()) { if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK) return false; RHS.makeComplexFloat(); RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics()); } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) return false; if (LHS.isComplexFloat()) { APFloat::cmpResult CR_r = LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); APFloat::cmpResult CR_i = LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual; return Success(IsEqual ? CCR::Equal : CCR::Nonequal, E); } else { assert(IsEquality && "invalid complex comparison"); bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() && LHS.getComplexIntImag() == RHS.getComplexIntImag(); return Success(IsEqual ? CCR::Equal : CCR::Nonequal, E); } } if (LHSTy->isRealFloatingType() && RHSTy->isRealFloatingType()) { APFloat RHS(0.0), LHS(0.0); bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) return false; assert(E->isComparisonOp() && "Invalid binary operator!"); auto GetCmpRes = [&]() { switch (LHS.compare(RHS)) { case APFloat::cmpEqual: return CCR::Equal; case APFloat::cmpLessThan: return CCR::Less; case APFloat::cmpGreaterThan: return CCR::Greater; case APFloat::cmpUnordered: return CCR::Unordered; } llvm_unreachable("Unrecognised APFloat::cmpResult enum"); }; return Success(GetCmpRes(), E); } if (LHSTy->isPointerType() && RHSTy->isPointerType()) { LValue LHSValue, RHSValue; bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) return false; // Reject differing bases from the normal codepath; we special-case // comparisons to null. if (!HasSameBase(LHSValue, RHSValue)) { // Inequalities and subtractions between unrelated pointers have // unspecified or undefined behavior. if (!IsEquality) return Error(E); // A constant address may compare equal to the address of a symbol. // The one exception is that address of an object cannot compare equal // to a null pointer constant. if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || (!RHSValue.Base && !RHSValue.Offset.isZero())) return Error(E); // It's implementation-defined whether distinct literals will have // distinct addresses. In clang, the result of such a comparison is // unspecified, so it is not a constant expression. However, we do know // that the address of a literal will be non-null. if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && LHSValue.Base && RHSValue.Base) return Error(E); // We can't tell whether weak symbols will end up pointing to the same // object. if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) return Error(E); // We can't compare the address of the start of one object with the // past-the-end address of another object, per C++ DR1652. if ((LHSValue.Base && LHSValue.Offset.isZero() && isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) || (RHSValue.Base && RHSValue.Offset.isZero() && isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue))) return Error(E); // We can't tell whether an object is at the same address as another // zero sized object. if ((RHSValue.Base && isZeroSized(LHSValue)) || (LHSValue.Base && isZeroSized(RHSValue))) return Error(E); return Success(CCR::Nonequal, E); } const CharUnits &LHSOffset = LHSValue.getLValueOffset(); const CharUnits &RHSOffset = RHSValue.getLValueOffset(); SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); // C++11 [expr.rel]p3: // Pointers to void (after pointer conversions) can be compared, with a // result defined as follows: If both pointers represent the same // address or are both the null pointer value, the result is true if the // operator is <= or >= and false otherwise; otherwise the result is // unspecified. // We interpret this as applying to pointers to *cv* void. if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && IsRelational) Info.CCEDiag(E, diag::note_constexpr_void_comparison); // C++11 [expr.rel]p2: // - If two pointers point to non-static data members of the same object, // or to subobjects or array elements fo such members, recursively, the // pointer to the later declared member compares greater provided the // two members have the same access control and provided their class is // not a union. // [...] // - Otherwise pointer comparisons are unspecified. if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) { bool WasArrayIndex; unsigned Mismatch = FindDesignatorMismatch( getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex); // At the point where the designators diverge, the comparison has a // specified value if: // - we are comparing array indices // - we are comparing fields of a union, or fields with the same access // Otherwise, the result is unspecified and thus the comparison is not a // constant expression. if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && Mismatch < RHSDesignator.Entries.size()) { const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); if (!LF && !RF) Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); else if (!LF) Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) << getAsBaseClass(LHSDesignator.Entries[Mismatch]) << RF->getParent() << RF; else if (!RF) Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) << getAsBaseClass(RHSDesignator.Entries[Mismatch]) << LF->getParent() << LF; else if (!LF->getParent()->isUnion() && LF->getAccess() != RF->getAccess()) Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_differing_access) << LF << LF->getAccess() << RF << RF->getAccess() << LF->getParent(); } } // The comparison here must be unsigned, and performed with the same // width as the pointer. unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); uint64_t CompareLHS = LHSOffset.getQuantity(); uint64_t CompareRHS = RHSOffset.getQuantity(); assert(PtrSize <= 64 && "Unexpected pointer width"); uint64_t Mask = ~0ULL >> (64 - PtrSize); CompareLHS &= Mask; CompareRHS &= Mask; // If there is a base and this is a relational operator, we can only // compare pointers within the object in question; otherwise, the result // depends on where the object is located in memory. if (!LHSValue.Base.isNull() && IsRelational) { QualType BaseTy = getType(LHSValue.Base); if (BaseTy->isIncompleteType()) return Error(E); CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); uint64_t OffsetLimit = Size.getQuantity(); if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) return Error(E); } if (CompareLHS < CompareRHS) return Success(CCR::Less, E); if (CompareLHS > CompareRHS) return Success(CCR::Greater, E); return Success(CCR::Equal, E); } if (LHSTy->isMemberPointerType()) { assert(IsEquality && "unexpected member pointer operation"); assert(RHSTy->isMemberPointerType() && "invalid comparison"); MemberPtr LHSValue, RHSValue; bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) return false; // C++11 [expr.eq]p2: // If both operands are null, they compare equal. Otherwise if only one is // null, they compare unequal. if (!LHSValue.getDecl() || !RHSValue.getDecl()) { bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); return Success(Equal ? CCR::Equal : CCR::Nonequal, E); } // Otherwise if either is a pointer to a virtual member function, the // result is unspecified. if (const CXXMethodDecl *MD = dyn_cast(LHSValue.getDecl())) if (MD->isVirtual()) Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; if (const CXXMethodDecl *MD = dyn_cast(RHSValue.getDecl())) if (MD->isVirtual()) Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; // Otherwise they compare equal if and only if they would refer to the // same member of the same most derived object or the same subobject if // they were dereferenced with a hypothetical object of the associated // class type. bool Equal = LHSValue == RHSValue; return Success(Equal ? CCR::Equal : CCR::Nonequal, E); } if (LHSTy->isNullPtrType()) { assert(E->isComparisonOp() && "unexpected nullptr operation"); assert(RHSTy->isNullPtrType() && "missing pointer conversion"); // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t // are compared, the result is true of the operator is <=, >= or ==, and // false otherwise. return Success(CCR::Equal, E); } return DoAfter(); } bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) { if (!CheckLiteralType(Info, E)) return false; auto OnSuccess = [&](ComparisonCategoryResult ResKind, const BinaryOperator *E) { // Evaluation succeeded. Lookup the information for the comparison category // type and fetch the VarDecl for the result. const ComparisonCategoryInfo &CmpInfo = Info.Ctx.CompCategories.getInfoForType(E->getType()); const VarDecl *VD = CmpInfo.getValueInfo(CmpInfo.makeWeakResult(ResKind))->VD; // Check and evaluate the result as a constant expression. LValue LV; LV.set(VD); if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) return false; return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); }; return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() { return ExprEvaluatorBaseTy::VisitBinCmp(E); }); } bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { // We don't call noteFailure immediately because the assignment happens after // we evaluate LHS and RHS. if (!Info.keepEvaluatingAfterFailure() && E->isAssignmentOp()) return Error(E); DelayedNoteFailureRAII MaybeNoteFailureLater(Info, E->isAssignmentOp()); if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() || !E->getRHS()->getType()->isIntegralOrEnumerationType()) && "DataRecursiveIntBinOpEvaluator should have handled integral types"); if (E->isComparisonOp()) { // Evaluate builtin binary comparisons by evaluating them as C++2a three-way // comparisons and then translating the result. auto OnSuccess = [&](ComparisonCategoryResult ResKind, const BinaryOperator *E) { using CCR = ComparisonCategoryResult; bool IsEqual = ResKind == CCR::Equal, IsLess = ResKind == CCR::Less, IsGreater = ResKind == CCR::Greater; auto Op = E->getOpcode(); switch (Op) { default: llvm_unreachable("unsupported binary operator"); case BO_EQ: case BO_NE: return Success(IsEqual == (Op == BO_EQ), E); case BO_LT: return Success(IsLess, E); case BO_GT: return Success(IsGreater, E); case BO_LE: return Success(IsEqual || IsLess, E); case BO_GE: return Success(IsEqual || IsGreater, E); } }; return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() { return ExprEvaluatorBaseTy::VisitBinaryOperator(E); }); } QualType LHSTy = E->getLHS()->getType(); QualType RHSTy = E->getRHS()->getType(); if (LHSTy->isPointerType() && RHSTy->isPointerType() && E->getOpcode() == BO_Sub) { LValue LHSValue, RHSValue; bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) return false; // Reject differing bases from the normal codepath; we special-case // comparisons to null. if (!HasSameBase(LHSValue, RHSValue)) { // Handle &&A - &&B. if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) return Error(E); const Expr *LHSExpr = LHSValue.Base.dyn_cast(); const Expr *RHSExpr = RHSValue.Base.dyn_cast(); if (!LHSExpr || !RHSExpr) return Error(E); const AddrLabelExpr *LHSAddrExpr = dyn_cast(LHSExpr); const AddrLabelExpr *RHSAddrExpr = dyn_cast(RHSExpr); if (!LHSAddrExpr || !RHSAddrExpr) return Error(E); // Make sure both labels come from the same function. if (LHSAddrExpr->getLabel()->getDeclContext() != RHSAddrExpr->getLabel()->getDeclContext()) return Error(E); return Success(APValue(LHSAddrExpr, RHSAddrExpr), E); } const CharUnits &LHSOffset = LHSValue.getLValueOffset(); const CharUnits &RHSOffset = RHSValue.getLValueOffset(); SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); // C++11 [expr.add]p6: // Unless both pointers point to elements of the same array object, or // one past the last element of the array object, the behavior is // undefined. if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && !AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator, RHSDesignator)) Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); QualType Type = E->getLHS()->getType(); QualType ElementType = Type->getAs()->getPointeeType(); CharUnits ElementSize; if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) return false; // As an extension, a type may have zero size (empty struct or union in // C, array of zero length). Pointer subtraction in such cases has // undefined behavior, so is not constant. if (ElementSize.isZero()) { Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size) << ElementType; return false; } // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, // and produce incorrect results when it overflows. Such behavior // appears to be non-conforming, but is common, so perhaps we should // assume the standard intended for such cases to be undefined behavior // and check for them. // Compute (LHSOffset - RHSOffset) / Size carefully, checking for // overflow in the final conversion to ptrdiff_t. APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), false); APSInt TrueResult = (LHS - RHS) / ElemSize; APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); if (Result.extend(65) != TrueResult && !HandleOverflow(Info, E, TrueResult, E->getType())) return false; return Success(Result, E); } return ExprEvaluatorBaseTy::VisitBinaryOperator(E); } /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with /// a result as the expression's type. bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( const UnaryExprOrTypeTraitExpr *E) { switch(E->getKind()) { case UETT_PreferredAlignOf: case UETT_AlignOf: { if (E->isArgumentType()) return Success(GetAlignOfType(Info, E->getArgumentType(), E->getKind()), E); else return Success(GetAlignOfExpr(Info, E->getArgumentExpr(), E->getKind()), E); } case UETT_VecStep: { QualType Ty = E->getTypeOfArgument(); if (Ty->isVectorType()) { unsigned n = Ty->castAs()->getNumElements(); // The vec_step built-in functions that take a 3-component // vector return 4. (OpenCL 1.1 spec 6.11.12) if (n == 3) n = 4; return Success(n, E); } else return Success(1, E); } case UETT_SizeOf: { QualType SrcTy = E->getTypeOfArgument(); // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, // the result is the size of the referenced type." if (const ReferenceType *Ref = SrcTy->getAs()) SrcTy = Ref->getPointeeType(); CharUnits Sizeof; if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) return false; return Success(Sizeof, E); } case UETT_OpenMPRequiredSimdAlign: assert(E->isArgumentType()); return Success( Info.Ctx.toCharUnitsFromBits( Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType())) .getQuantity(), E); } llvm_unreachable("unknown expr/type trait"); } bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { CharUnits Result; unsigned n = OOE->getNumComponents(); if (n == 0) return Error(OOE); QualType CurrentType = OOE->getTypeSourceInfo()->getType(); for (unsigned i = 0; i != n; ++i) { OffsetOfNode ON = OOE->getComponent(i); switch (ON.getKind()) { case OffsetOfNode::Array: { const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); APSInt IdxResult; if (!EvaluateInteger(Idx, IdxResult, Info)) return false; const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); if (!AT) return Error(OOE); CurrentType = AT->getElementType(); CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); Result += IdxResult.getSExtValue() * ElementSize; break; } case OffsetOfNode::Field: { FieldDecl *MemberDecl = ON.getField(); const RecordType *RT = CurrentType->getAs(); if (!RT) return Error(OOE); RecordDecl *RD = RT->getDecl(); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); unsigned i = MemberDecl->getFieldIndex(); assert(i < RL.getFieldCount() && "offsetof field in wrong type"); Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); CurrentType = MemberDecl->getType().getNonReferenceType(); break; } case OffsetOfNode::Identifier: llvm_unreachable("dependent __builtin_offsetof"); case OffsetOfNode::Base: { CXXBaseSpecifier *BaseSpec = ON.getBase(); if (BaseSpec->isVirtual()) return Error(OOE); // Find the layout of the class whose base we are looking into. const RecordType *RT = CurrentType->getAs(); if (!RT) return Error(OOE); RecordDecl *RD = RT->getDecl(); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); // Find the base class itself. CurrentType = BaseSpec->getType(); const RecordType *BaseRT = CurrentType->getAs(); if (!BaseRT) return Error(OOE); // Add the offset to the base. Result += RL.getBaseClassOffset(cast(BaseRT->getDecl())); break; } } } return Success(Result, OOE); } bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { switch (E->getOpcode()) { default: // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. // See C99 6.6p3. return Error(E); case UO_Extension: // FIXME: Should extension allow i-c-e extension expressions in its scope? // If so, we could clear the diagnostic ID. return Visit(E->getSubExpr()); case UO_Plus: // The result is just the value. return Visit(E->getSubExpr()); case UO_Minus: { if (!Visit(E->getSubExpr())) return false; if (!Result.isInt()) return Error(E); const APSInt &Value = Result.getInt(); if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() && !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), E->getType())) return false; return Success(-Value, E); } case UO_Not: { if (!Visit(E->getSubExpr())) return false; if (!Result.isInt()) return Error(E); return Success(~Result.getInt(), E); } case UO_LNot: { bool bres; if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) return false; return Success(!bres, E); } } } /// HandleCast - This is used to evaluate implicit or explicit casts where the /// result type is integer. bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { const Expr *SubExpr = E->getSubExpr(); QualType DestType = E->getType(); QualType SrcType = SubExpr->getType(); switch (E->getCastKind()) { case CK_BaseToDerived: case CK_DerivedToBase: case CK_UncheckedDerivedToBase: case CK_Dynamic: case CK_ToUnion: case CK_ArrayToPointerDecay: case CK_FunctionToPointerDecay: case CK_NullToPointer: case CK_NullToMemberPointer: case CK_BaseToDerivedMemberPointer: case CK_DerivedToBaseMemberPointer: case CK_ReinterpretMemberPointer: case CK_ConstructorConversion: case CK_IntegralToPointer: case CK_ToVoid: case CK_VectorSplat: case CK_IntegralToFloating: case CK_FloatingCast: case CK_CPointerToObjCPointerCast: case CK_BlockPointerToObjCPointerCast: case CK_AnyPointerToBlockPointerCast: case CK_ObjCObjectLValueCast: case CK_FloatingRealToComplex: case CK_FloatingComplexToReal: case CK_FloatingComplexCast: case CK_FloatingComplexToIntegralComplex: case CK_IntegralRealToComplex: case CK_IntegralComplexCast: case CK_IntegralComplexToFloatingComplex: case CK_BuiltinFnToFnPtr: case CK_ZeroToOCLOpaqueType: case CK_NonAtomicToAtomic: case CK_AddressSpaceConversion: case CK_IntToOCLSampler: case CK_FixedPointCast: case CK_IntegralToFixedPoint: llvm_unreachable("invalid cast kind for integral value"); case CK_BitCast: case CK_Dependent: case CK_LValueBitCast: case CK_ARCProduceObject: case CK_ARCConsumeObject: case CK_ARCReclaimReturnedObject: case CK_ARCExtendBlockObject: case CK_CopyAndAutoreleaseBlockObject: return Error(E); case CK_UserDefinedConversion: case CK_LValueToRValue: case CK_AtomicToNonAtomic: case CK_NoOp: case CK_LValueToRValueBitCast: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_MemberPointerToBoolean: case CK_PointerToBoolean: case CK_IntegralToBoolean: case CK_FloatingToBoolean: case CK_BooleanToSignedIntegral: case CK_FloatingComplexToBoolean: case CK_IntegralComplexToBoolean: { bool BoolResult; if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) return false; uint64_t IntResult = BoolResult; if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral) IntResult = (uint64_t)-1; return Success(IntResult, E); } case CK_FixedPointToIntegral: { APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SrcType)); if (!EvaluateFixedPoint(SubExpr, Src, Info)) return false; bool Overflowed; llvm::APSInt Result = Src.convertToInt( Info.Ctx.getIntWidth(DestType), DestType->isSignedIntegerOrEnumerationType(), &Overflowed); if (Overflowed && !HandleOverflow(Info, E, Result, DestType)) return false; return Success(Result, E); } case CK_FixedPointToBoolean: { // Unsigned padding does not affect this. APValue Val; if (!Evaluate(Val, Info, SubExpr)) return false; return Success(Val.getFixedPoint().getBoolValue(), E); } case CK_IntegralCast: { if (!Visit(SubExpr)) return false; if (!Result.isInt()) { // Allow casts of address-of-label differences if they are no-ops // or narrowing. (The narrowing case isn't actually guaranteed to // be constant-evaluatable except in some narrow cases which are hard // to detect here. We let it through on the assumption the user knows // what they are doing.) if (Result.isAddrLabelDiff()) return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); // Only allow casts of lvalues if they are lossless. return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); } return Success(HandleIntToIntCast(Info, E, DestType, SrcType, Result.getInt()), E); } case CK_PointerToIntegral: { CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; LValue LV; if (!EvaluatePointer(SubExpr, LV, Info)) return false; if (LV.getLValueBase()) { // Only allow based lvalue casts if they are lossless. // FIXME: Allow a larger integer size than the pointer size, and allow // narrowing back down to pointer width in subsequent integral casts. // FIXME: Check integer type's active bits, not its type size. if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) return Error(E); LV.Designator.setInvalid(); LV.moveInto(Result); return true; } APSInt AsInt; APValue V; LV.moveInto(V); if (!V.toIntegralConstant(AsInt, SrcType, Info.Ctx)) llvm_unreachable("Can't cast this!"); return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); } case CK_IntegralComplexToReal: { ComplexValue C; if (!EvaluateComplex(SubExpr, C, Info)) return false; return Success(C.getComplexIntReal(), E); } case CK_FloatingToIntegral: { APFloat F(0.0); if (!EvaluateFloat(SubExpr, F, Info)) return false; APSInt Value; if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) return false; return Success(Value, E); } } llvm_unreachable("unknown cast resulting in integral value"); } bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isAnyComplexType()) { ComplexValue LV; if (!EvaluateComplex(E->getSubExpr(), LV, Info)) return false; if (!LV.isComplexInt()) return Error(E); return Success(LV.getComplexIntReal(), E); } return Visit(E->getSubExpr()); } bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isComplexIntegerType()) { ComplexValue LV; if (!EvaluateComplex(E->getSubExpr(), LV, Info)) return false; if (!LV.isComplexInt()) return Error(E); return Success(LV.getComplexIntImag(), E); } VisitIgnoredValue(E->getSubExpr()); return Success(0, E); } bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { return Success(E->getPackLength(), E); } bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { return Success(E->getValue(), E); } bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { switch (E->getOpcode()) { default: // Invalid unary operators return Error(E); case UO_Plus: // The result is just the value. return Visit(E->getSubExpr()); case UO_Minus: { if (!Visit(E->getSubExpr())) return false; if (!Result.isFixedPoint()) return Error(E); bool Overflowed; APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed); if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType())) return false; return Success(Negated, E); } case UO_LNot: { bool bres; if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) return false; return Success(!bres, E); } } } bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) { const Expr *SubExpr = E->getSubExpr(); QualType DestType = E->getType(); assert(DestType->isFixedPointType() && "Expected destination type to be a fixed point type"); auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType); switch (E->getCastKind()) { case CK_FixedPointCast: { APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType())); if (!EvaluateFixedPoint(SubExpr, Src, Info)) return false; bool Overflowed; APFixedPoint Result = Src.convert(DestFXSema, &Overflowed); if (Overflowed && !HandleOverflow(Info, E, Result, DestType)) return false; return Success(Result, E); } case CK_IntegralToFixedPoint: { APSInt Src; if (!EvaluateInteger(SubExpr, Src, Info)) return false; bool Overflowed; APFixedPoint IntResult = APFixedPoint::getFromIntValue( Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed); if (Overflowed && !HandleOverflow(Info, E, IntResult, DestType)) return false; return Success(IntResult, E); } case CK_NoOp: case CK_LValueToRValue: return ExprEvaluatorBaseTy::VisitCastExpr(E); default: return Error(E); } } bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { const Expr *LHS = E->getLHS(); const Expr *RHS = E->getRHS(); FixedPointSemantics ResultFXSema = Info.Ctx.getFixedPointSemantics(E->getType()); APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType())); if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info)) return false; APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType())); if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info)) return false; switch (E->getOpcode()) { case BO_Add: { bool AddOverflow, ConversionOverflow; APFixedPoint Result = LHSFX.add(RHSFX, &AddOverflow) .convert(ResultFXSema, &ConversionOverflow); if ((AddOverflow || ConversionOverflow) && !HandleOverflow(Info, E, Result, E->getType())) return false; return Success(Result, E); } default: return false; } llvm_unreachable("Should've exited before this"); } //===----------------------------------------------------------------------===// // Float Evaluation //===----------------------------------------------------------------------===// namespace { class FloatExprEvaluator : public ExprEvaluatorBase { APFloat &Result; public: FloatExprEvaluator(EvalInfo &info, APFloat &result) : ExprEvaluatorBaseTy(info), Result(result) {} bool Success(const APValue &V, const Expr *e) { Result = V.getFloat(); return true; } bool ZeroInitialization(const Expr *E) { Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); return true; } bool VisitCallExpr(const CallExpr *E); bool VisitUnaryOperator(const UnaryOperator *E); bool VisitBinaryOperator(const BinaryOperator *E); bool VisitFloatingLiteral(const FloatingLiteral *E); bool VisitCastExpr(const CastExpr *E); bool VisitUnaryReal(const UnaryOperator *E); bool VisitUnaryImag(const UnaryOperator *E); // FIXME: Missing: array subscript of vector, member of vector }; } // end anonymous namespace static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isRealFloatingType()); return FloatExprEvaluator(Info, Result).Visit(E); } static bool TryEvaluateBuiltinNaN(const ASTContext &Context, QualType ResultTy, const Expr *Arg, bool SNaN, llvm::APFloat &Result) { const StringLiteral *S = dyn_cast(Arg->IgnoreParenCasts()); if (!S) return false; const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); llvm::APInt fill; // Treat empty strings as if they were zero. if (S->getString().empty()) fill = llvm::APInt(32, 0); else if (S->getString().getAsInteger(0, fill)) return false; if (Context.getTargetInfo().isNan2008()) { if (SNaN) Result = llvm::APFloat::getSNaN(Sem, false, &fill); else Result = llvm::APFloat::getQNaN(Sem, false, &fill); } else { // Prior to IEEE 754-2008, architectures were allowed to choose whether // the first bit of their significand was set for qNaN or sNaN. MIPS chose // a different encoding to what became a standard in 2008, and for pre- // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as // sNaN. This is now known as "legacy NaN" encoding. if (SNaN) Result = llvm::APFloat::getQNaN(Sem, false, &fill); else Result = llvm::APFloat::getSNaN(Sem, false, &fill); } return true; } bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { switch (E->getBuiltinCallee()) { default: return ExprEvaluatorBaseTy::VisitCallExpr(E); case Builtin::BI__builtin_huge_val: case Builtin::BI__builtin_huge_valf: case Builtin::BI__builtin_huge_vall: case Builtin::BI__builtin_huge_valf128: case Builtin::BI__builtin_inf: case Builtin::BI__builtin_inff: case Builtin::BI__builtin_infl: case Builtin::BI__builtin_inff128: { const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); Result = llvm::APFloat::getInf(Sem); return true; } case Builtin::BI__builtin_nans: case Builtin::BI__builtin_nansf: case Builtin::BI__builtin_nansl: case Builtin::BI__builtin_nansf128: if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), true, Result)) return Error(E); return true; case Builtin::BI__builtin_nan: case Builtin::BI__builtin_nanf: case Builtin::BI__builtin_nanl: case Builtin::BI__builtin_nanf128: // If this is __builtin_nan() turn this into a nan, otherwise we // can't constant fold it. if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), false, Result)) return Error(E); return true; case Builtin::BI__builtin_fabs: case Builtin::BI__builtin_fabsf: case Builtin::BI__builtin_fabsl: case Builtin::BI__builtin_fabsf128: if (!EvaluateFloat(E->getArg(0), Result, Info)) return false; if (Result.isNegative()) Result.changeSign(); return true; // FIXME: Builtin::BI__builtin_powi // FIXME: Builtin::BI__builtin_powif // FIXME: Builtin::BI__builtin_powil case Builtin::BI__builtin_copysign: case Builtin::BI__builtin_copysignf: case Builtin::BI__builtin_copysignl: case Builtin::BI__builtin_copysignf128: { APFloat RHS(0.); if (!EvaluateFloat(E->getArg(0), Result, Info) || !EvaluateFloat(E->getArg(1), RHS, Info)) return false; Result.copySign(RHS); return true; } } } bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isAnyComplexType()) { ComplexValue CV; if (!EvaluateComplex(E->getSubExpr(), CV, Info)) return false; Result = CV.FloatReal; return true; } return Visit(E->getSubExpr()); } bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isAnyComplexType()) { ComplexValue CV; if (!EvaluateComplex(E->getSubExpr(), CV, Info)) return false; Result = CV.FloatImag; return true; } VisitIgnoredValue(E->getSubExpr()); const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); Result = llvm::APFloat::getZero(Sem); return true; } bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { switch (E->getOpcode()) { default: return Error(E); case UO_Plus: return EvaluateFloat(E->getSubExpr(), Result, Info); case UO_Minus: if (!EvaluateFloat(E->getSubExpr(), Result, Info)) return false; Result.changeSign(); return true; } } bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) return ExprEvaluatorBaseTy::VisitBinaryOperator(E); APFloat RHS(0.0); bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); if (!LHSOK && !Info.noteFailure()) return false; return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK && handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS); } bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { Result = E->getValue(); return true; } bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { const Expr* SubExpr = E->getSubExpr(); switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_IntegralToFloating: { APSInt IntResult; return EvaluateInteger(SubExpr, IntResult, Info) && HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult, E->getType(), Result); } case CK_FloatingCast: { if (!Visit(SubExpr)) return false; return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), Result); } case CK_FloatingComplexToReal: { ComplexValue V; if (!EvaluateComplex(SubExpr, V, Info)) return false; Result = V.getComplexFloatReal(); return true; } } } //===----------------------------------------------------------------------===// // Complex Evaluation (for float and integer) //===----------------------------------------------------------------------===// namespace { class ComplexExprEvaluator : public ExprEvaluatorBase { ComplexValue &Result; public: ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) : ExprEvaluatorBaseTy(info), Result(Result) {} bool Success(const APValue &V, const Expr *e) { Result.setFrom(V); return true; } bool ZeroInitialization(const Expr *E); //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// bool VisitImaginaryLiteral(const ImaginaryLiteral *E); bool VisitCastExpr(const CastExpr *E); bool VisitBinaryOperator(const BinaryOperator *E); bool VisitUnaryOperator(const UnaryOperator *E); bool VisitInitListExpr(const InitListExpr *E); }; } // end anonymous namespace static bool EvaluateComplex(const Expr *E, ComplexValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isAnyComplexType()); return ComplexExprEvaluator(Info, Result).Visit(E); } bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { QualType ElemTy = E->getType()->castAs()->getElementType(); if (ElemTy->isRealFloatingType()) { Result.makeComplexFloat(); APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); Result.FloatReal = Zero; Result.FloatImag = Zero; } else { Result.makeComplexInt(); APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); Result.IntReal = Zero; Result.IntImag = Zero; } return true; } bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { const Expr* SubExpr = E->getSubExpr(); if (SubExpr->getType()->isRealFloatingType()) { Result.makeComplexFloat(); APFloat &Imag = Result.FloatImag; if (!EvaluateFloat(SubExpr, Imag, Info)) return false; Result.FloatReal = APFloat(Imag.getSemantics()); return true; } else { assert(SubExpr->getType()->isIntegerType() && "Unexpected imaginary literal."); Result.makeComplexInt(); APSInt &Imag = Result.IntImag; if (!EvaluateInteger(SubExpr, Imag, Info)) return false; Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); return true; } } bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { case CK_BitCast: case CK_BaseToDerived: case CK_DerivedToBase: case CK_UncheckedDerivedToBase: case CK_Dynamic: case CK_ToUnion: case CK_ArrayToPointerDecay: case CK_FunctionToPointerDecay: case CK_NullToPointer: case CK_NullToMemberPointer: case CK_BaseToDerivedMemberPointer: case CK_DerivedToBaseMemberPointer: case CK_MemberPointerToBoolean: case CK_ReinterpretMemberPointer: case CK_ConstructorConversion: case CK_IntegralToPointer: case CK_PointerToIntegral: case CK_PointerToBoolean: case CK_ToVoid: case CK_VectorSplat: case CK_IntegralCast: case CK_BooleanToSignedIntegral: case CK_IntegralToBoolean: case CK_IntegralToFloating: case CK_FloatingToIntegral: case CK_FloatingToBoolean: case CK_FloatingCast: case CK_CPointerToObjCPointerCast: case CK_BlockPointerToObjCPointerCast: case CK_AnyPointerToBlockPointerCast: case CK_ObjCObjectLValueCast: case CK_FloatingComplexToReal: case CK_FloatingComplexToBoolean: case CK_IntegralComplexToReal: case CK_IntegralComplexToBoolean: case CK_ARCProduceObject: case CK_ARCConsumeObject: case CK_ARCReclaimReturnedObject: case CK_ARCExtendBlockObject: case CK_CopyAndAutoreleaseBlockObject: case CK_BuiltinFnToFnPtr: case CK_ZeroToOCLOpaqueType: case CK_NonAtomicToAtomic: case CK_AddressSpaceConversion: case CK_IntToOCLSampler: case CK_FixedPointCast: case CK_FixedPointToBoolean: case CK_FixedPointToIntegral: case CK_IntegralToFixedPoint: llvm_unreachable("invalid cast kind for complex value"); case CK_LValueToRValue: case CK_AtomicToNonAtomic: case CK_NoOp: case CK_LValueToRValueBitCast: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_Dependent: case CK_LValueBitCast: case CK_UserDefinedConversion: return Error(E); case CK_FloatingRealToComplex: { APFloat &Real = Result.FloatReal; if (!EvaluateFloat(E->getSubExpr(), Real, Info)) return false; Result.makeComplexFloat(); Result.FloatImag = APFloat(Real.getSemantics()); return true; } case CK_FloatingComplexCast: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->getAs()->getElementType(); QualType From = E->getSubExpr()->getType()->getAs()->getElementType(); return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); } case CK_FloatingComplexToIntegralComplex: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->getAs()->getElementType(); QualType From = E->getSubExpr()->getType()->getAs()->getElementType(); Result.makeComplexInt(); return HandleFloatToIntCast(Info, E, From, Result.FloatReal, To, Result.IntReal) && HandleFloatToIntCast(Info, E, From, Result.FloatImag, To, Result.IntImag); } case CK_IntegralRealToComplex: { APSInt &Real = Result.IntReal; if (!EvaluateInteger(E->getSubExpr(), Real, Info)) return false; Result.makeComplexInt(); Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); return true; } case CK_IntegralComplexCast: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->getAs()->getElementType(); QualType From = E->getSubExpr()->getType()->getAs()->getElementType(); Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); return true; } case CK_IntegralComplexToFloatingComplex: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->castAs()->getElementType(); QualType From = E->getSubExpr()->getType()->castAs()->getElementType(); Result.makeComplexFloat(); return HandleIntToFloatCast(Info, E, From, Result.IntReal, To, Result.FloatReal) && HandleIntToFloatCast(Info, E, From, Result.IntImag, To, Result.FloatImag); } } llvm_unreachable("unknown cast resulting in complex value"); } bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) return ExprEvaluatorBaseTy::VisitBinaryOperator(E); // Track whether the LHS or RHS is real at the type system level. When this is // the case we can simplify our evaluation strategy. bool LHSReal = false, RHSReal = false; bool LHSOK; if (E->getLHS()->getType()->isRealFloatingType()) { LHSReal = true; APFloat &Real = Result.FloatReal; LHSOK = EvaluateFloat(E->getLHS(), Real, Info); if (LHSOK) { Result.makeComplexFloat(); Result.FloatImag = APFloat(Real.getSemantics()); } } else { LHSOK = Visit(E->getLHS()); } if (!LHSOK && !Info.noteFailure()) return false; ComplexValue RHS; if (E->getRHS()->getType()->isRealFloatingType()) { RHSReal = true; APFloat &Real = RHS.FloatReal; if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK) return false; RHS.makeComplexFloat(); RHS.FloatImag = APFloat(Real.getSemantics()); } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) return false; assert(!(LHSReal && RHSReal) && "Cannot have both operands of a complex operation be real."); switch (E->getOpcode()) { default: return Error(E); case BO_Add: if (Result.isComplexFloat()) { Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), APFloat::rmNearestTiesToEven); if (LHSReal) Result.getComplexFloatImag() = RHS.getComplexFloatImag(); else if (!RHSReal) Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), APFloat::rmNearestTiesToEven); } else { Result.getComplexIntReal() += RHS.getComplexIntReal(); Result.getComplexIntImag() += RHS.getComplexIntImag(); } break; case BO_Sub: if (Result.isComplexFloat()) { Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), APFloat::rmNearestTiesToEven); if (LHSReal) { Result.getComplexFloatImag() = RHS.getComplexFloatImag(); Result.getComplexFloatImag().changeSign(); } else if (!RHSReal) { Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), APFloat::rmNearestTiesToEven); } } else { Result.getComplexIntReal() -= RHS.getComplexIntReal(); Result.getComplexIntImag() -= RHS.getComplexIntImag(); } break; case BO_Mul: if (Result.isComplexFloat()) { // This is an implementation of complex multiplication according to the // constraints laid out in C11 Annex G. The implementation uses the // following naming scheme: // (a + ib) * (c + id) ComplexValue LHS = Result; APFloat &A = LHS.getComplexFloatReal(); APFloat &B = LHS.getComplexFloatImag(); APFloat &C = RHS.getComplexFloatReal(); APFloat &D = RHS.getComplexFloatImag(); APFloat &ResR = Result.getComplexFloatReal(); APFloat &ResI = Result.getComplexFloatImag(); if (LHSReal) { assert(!RHSReal && "Cannot have two real operands for a complex op!"); ResR = A * C; ResI = A * D; } else if (RHSReal) { ResR = C * A; ResI = C * B; } else { // In the fully general case, we need to handle NaNs and infinities // robustly. APFloat AC = A * C; APFloat BD = B * D; APFloat AD = A * D; APFloat BC = B * C; ResR = AC - BD; ResI = AD + BC; if (ResR.isNaN() && ResI.isNaN()) { bool Recalc = false; if (A.isInfinity() || B.isInfinity()) { A = APFloat::copySign( APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); B = APFloat::copySign( APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); if (C.isNaN()) C = APFloat::copySign(APFloat(C.getSemantics()), C); if (D.isNaN()) D = APFloat::copySign(APFloat(D.getSemantics()), D); Recalc = true; } if (C.isInfinity() || D.isInfinity()) { C = APFloat::copySign( APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); D = APFloat::copySign( APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); if (A.isNaN()) A = APFloat::copySign(APFloat(A.getSemantics()), A); if (B.isNaN()) B = APFloat::copySign(APFloat(B.getSemantics()), B); Recalc = true; } if (!Recalc && (AC.isInfinity() || BD.isInfinity() || AD.isInfinity() || BC.isInfinity())) { if (A.isNaN()) A = APFloat::copySign(APFloat(A.getSemantics()), A); if (B.isNaN()) B = APFloat::copySign(APFloat(B.getSemantics()), B); if (C.isNaN()) C = APFloat::copySign(APFloat(C.getSemantics()), C); if (D.isNaN()) D = APFloat::copySign(APFloat(D.getSemantics()), D); Recalc = true; } if (Recalc) { ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D); ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C); } } } } else { ComplexValue LHS = Result; Result.getComplexIntReal() = (LHS.getComplexIntReal() * RHS.getComplexIntReal() - LHS.getComplexIntImag() * RHS.getComplexIntImag()); Result.getComplexIntImag() = (LHS.getComplexIntReal() * RHS.getComplexIntImag() + LHS.getComplexIntImag() * RHS.getComplexIntReal()); } break; case BO_Div: if (Result.isComplexFloat()) { // This is an implementation of complex division according to the // constraints laid out in C11 Annex G. The implementation uses the // following naming scheme: // (a + ib) / (c + id) ComplexValue LHS = Result; APFloat &A = LHS.getComplexFloatReal(); APFloat &B = LHS.getComplexFloatImag(); APFloat &C = RHS.getComplexFloatReal(); APFloat &D = RHS.getComplexFloatImag(); APFloat &ResR = Result.getComplexFloatReal(); APFloat &ResI = Result.getComplexFloatImag(); if (RHSReal) { ResR = A / C; ResI = B / C; } else { if (LHSReal) { // No real optimizations we can do here, stub out with zero. B = APFloat::getZero(A.getSemantics()); } int DenomLogB = 0; APFloat MaxCD = maxnum(abs(C), abs(D)); if (MaxCD.isFinite()) { DenomLogB = ilogb(MaxCD); C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven); D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven); } APFloat Denom = C * C + D * D; ResR = scalbn((A * C + B * D) / Denom, -DenomLogB, APFloat::rmNearestTiesToEven); ResI = scalbn((B * C - A * D) / Denom, -DenomLogB, APFloat::rmNearestTiesToEven); if (ResR.isNaN() && ResI.isNaN()) { if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) { ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A; ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B; } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() && D.isFinite()) { A = APFloat::copySign( APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); B = APFloat::copySign( APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D); ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D); } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) { C = APFloat::copySign( APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); D = APFloat::copySign( APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D); ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D); } } } } else { if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) return Error(E, diag::note_expr_divide_by_zero); ComplexValue LHS = Result; APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + RHS.getComplexIntImag() * RHS.getComplexIntImag(); Result.getComplexIntReal() = (LHS.getComplexIntReal() * RHS.getComplexIntReal() + LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; Result.getComplexIntImag() = (LHS.getComplexIntImag() * RHS.getComplexIntReal() - LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; } break; } return true; } bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { // Get the operand value into 'Result'. if (!Visit(E->getSubExpr())) return false; switch (E->getOpcode()) { default: return Error(E); case UO_Extension: return true; case UO_Plus: // The result is always just the subexpr. return true; case UO_Minus: if (Result.isComplexFloat()) { Result.getComplexFloatReal().changeSign(); Result.getComplexFloatImag().changeSign(); } else { Result.getComplexIntReal() = -Result.getComplexIntReal(); Result.getComplexIntImag() = -Result.getComplexIntImag(); } return true; case UO_Not: if (Result.isComplexFloat()) Result.getComplexFloatImag().changeSign(); else Result.getComplexIntImag() = -Result.getComplexIntImag(); return true; } } bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { if (E->getNumInits() == 2) { if (E->getType()->isComplexType()) { Result.makeComplexFloat(); if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) return false; if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) return false; } else { Result.makeComplexInt(); if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) return false; if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) return false; } return true; } return ExprEvaluatorBaseTy::VisitInitListExpr(E); } //===----------------------------------------------------------------------===// // Atomic expression evaluation, essentially just handling the NonAtomicToAtomic // implicit conversion. //===----------------------------------------------------------------------===// namespace { class AtomicExprEvaluator : public ExprEvaluatorBase { const LValue *This; APValue &Result; public: AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result) : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result = V; return true; } bool ZeroInitialization(const Expr *E) { ImplicitValueInitExpr VIE( E->getType()->castAs()->getValueType()); // For atomic-qualified class (and array) types in C++, initialize the // _Atomic-wrapped subobject directly, in-place. return This ? EvaluateInPlace(Result, Info, *This, &VIE) : Evaluate(Result, Info, &VIE); } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_NonAtomicToAtomic: return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr()) : Evaluate(Result, Info, E->getSubExpr()); } } }; } // end anonymous namespace static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isAtomicType()); return AtomicExprEvaluator(Info, This, Result).Visit(E); } //===----------------------------------------------------------------------===// // Void expression evaluation, primarily for a cast to void on the LHS of a // comma operator //===----------------------------------------------------------------------===// namespace { class VoidExprEvaluator : public ExprEvaluatorBase { public: VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} bool Success(const APValue &V, const Expr *e) { return true; } bool ZeroInitialization(const Expr *E) { return true; } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_ToVoid: VisitIgnoredValue(E->getSubExpr()); return true; } } bool VisitCallExpr(const CallExpr *E) { switch (E->getBuiltinCallee()) { default: return ExprEvaluatorBaseTy::VisitCallExpr(E); case Builtin::BI__assume: case Builtin::BI__builtin_assume: // The argument is not evaluated! return true; } } }; } // end anonymous namespace static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isVoidType()); return VoidExprEvaluator(Info).Visit(E); } //===----------------------------------------------------------------------===// // Top level Expr::EvaluateAsRValue method. //===----------------------------------------------------------------------===// static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { // In C, function designators are not lvalues, but we evaluate them as if they // are. QualType T = E->getType(); if (E->isGLValue() || T->isFunctionType()) { LValue LV; if (!EvaluateLValue(E, LV, Info)) return false; LV.moveInto(Result); } else if (T->isVectorType()) { if (!EvaluateVector(E, Result, Info)) return false; } else if (T->isIntegralOrEnumerationType()) { if (!IntExprEvaluator(Info, Result).Visit(E)) return false; } else if (T->hasPointerRepresentation()) { LValue LV; if (!EvaluatePointer(E, LV, Info)) return false; LV.moveInto(Result); } else if (T->isRealFloatingType()) { llvm::APFloat F(0.0); if (!EvaluateFloat(E, F, Info)) return false; Result = APValue(F); } else if (T->isAnyComplexType()) { ComplexValue C; if (!EvaluateComplex(E, C, Info)) return false; C.moveInto(Result); } else if (T->isFixedPointType()) { if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false; } else if (T->isMemberPointerType()) { MemberPtr P; if (!EvaluateMemberPointer(E, P, Info)) return false; P.moveInto(Result); return true; } else if (T->isArrayType()) { LValue LV; APValue &Value = createTemporary(E, false, LV, *Info.CurrentCall); if (!EvaluateArray(E, LV, Value, Info)) return false; Result = Value; } else if (T->isRecordType()) { LValue LV; APValue &Value = createTemporary(E, false, LV, *Info.CurrentCall); if (!EvaluateRecord(E, LV, Value, Info)) return false; Result = Value; } else if (T->isVoidType()) { if (!Info.getLangOpts().CPlusPlus11) Info.CCEDiag(E, diag::note_constexpr_nonliteral) << E->getType(); if (!EvaluateVoid(E, Info)) return false; } else if (T->isAtomicType()) { QualType Unqual = T.getAtomicUnqualifiedType(); if (Unqual->isArrayType() || Unqual->isRecordType()) { LValue LV; APValue &Value = createTemporary(E, false, LV, *Info.CurrentCall); if (!EvaluateAtomic(E, &LV, Value, Info)) return false; } else { if (!EvaluateAtomic(E, nullptr, Result, Info)) return false; } } else if (Info.getLangOpts().CPlusPlus11) { Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType(); return false; } else { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } return true; } /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some /// cases, the in-place evaluation is essential, since later initializers for /// an object can indirectly refer to subobjects which were initialized earlier. static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, const Expr *E, bool AllowNonLiteralTypes) { assert(!E->isValueDependent()); if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This)) return false; if (E->isRValue()) { // Evaluate arrays and record types in-place, so that later initializers can // refer to earlier-initialized members of the object. QualType T = E->getType(); if (T->isArrayType()) return EvaluateArray(E, This, Result, Info); else if (T->isRecordType()) return EvaluateRecord(E, This, Result, Info); else if (T->isAtomicType()) { QualType Unqual = T.getAtomicUnqualifiedType(); if (Unqual->isArrayType() || Unqual->isRecordType()) return EvaluateAtomic(E, &This, Result, Info); } } // For any other type, in-place evaluation is unimportant. return Evaluate(Result, Info, E); } /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit /// lvalue-to-rvalue cast if it is an lvalue. static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { if (E->getType().isNull()) return false; if (!CheckLiteralType(Info, E)) return false; if (!::Evaluate(Result, Info, E)) return false; if (E->isGLValue()) { LValue LV; LV.setFrom(Info.Ctx, Result); if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) return false; } // Check this core constant expression is a constant expression. return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); } static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result, const ASTContext &Ctx, bool &IsConst) { // Fast-path evaluations of integer literals, since we sometimes see files // containing vast quantities of these. if (const IntegerLiteral *L = dyn_cast(Exp)) { Result.Val = APValue(APSInt(L->getValue(), L->getType()->isUnsignedIntegerType())); IsConst = true; return true; } // This case should be rare, but we need to check it before we check on // the type below. if (Exp->getType().isNull()) { IsConst = false; return true; } // FIXME: Evaluating values of large array and record types can cause // performance problems. Only do so in C++11 for now. if (Exp->isRValue() && (Exp->getType()->isArrayType() || Exp->getType()->isRecordType()) && !Ctx.getLangOpts().CPlusPlus11) { IsConst = false; return true; } return false; } static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result, Expr::SideEffectsKind SEK) { return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) || (SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior); } static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result, const ASTContext &Ctx, EvalInfo &Info) { bool IsConst; if (FastEvaluateAsRValue(E, Result, Ctx, IsConst)) return IsConst; return EvaluateAsRValue(Info, E, Result.Val); } static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult, const ASTContext &Ctx, Expr::SideEffectsKind AllowSideEffects, EvalInfo &Info) { if (!E->getType()->isIntegralOrEnumerationType()) return false; if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info) || !ExprResult.Val.isInt() || hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) return false; return true; } static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult, const ASTContext &Ctx, Expr::SideEffectsKind AllowSideEffects, EvalInfo &Info) { if (!E->getType()->isFixedPointType()) return false; if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info)) return false; if (!ExprResult.Val.isFixedPoint() || hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) return false; return true; } /// EvaluateAsRValue - Return true if this is a constant which we can fold using /// any crazy technique (that has nothing to do with language standards) that /// we want to. If this function returns true, it returns the folded constant /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion /// will be applied to the result. bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx, bool InConstantContext) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); Info.InConstantContext = InConstantContext; return ::EvaluateAsRValue(this, Result, Ctx, Info); } bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx, bool InConstantContext) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalResult Scratch; return EvaluateAsRValue(Scratch, Ctx, InConstantContext) && HandleConversionToBool(Scratch.Val, Result); } bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx, SideEffectsKind AllowSideEffects, bool InConstantContext) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); Info.InConstantContext = InConstantContext; return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info); } bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx, SideEffectsKind AllowSideEffects, bool InConstantContext) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); Info.InConstantContext = InConstantContext; return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info); } bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx, SideEffectsKind AllowSideEffects, bool InConstantContext) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); if (!getType()->isRealFloatingType()) return false; EvalResult ExprResult; if (!EvaluateAsRValue(ExprResult, Ctx, InConstantContext) || !ExprResult.Val.isFloat() || hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) return false; Result = ExprResult.Val.getFloat(); return true; } bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx, bool InConstantContext) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold); Info.InConstantContext = InConstantContext; LValue LV; if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || !CheckLValueConstantExpression(Info, getExprLoc(), Ctx.getLValueReferenceType(getType()), LV, Expr::EvaluateForCodeGen)) return false; LV.moveInto(Result.Val); return true; } bool Expr::EvaluateAsConstantExpr(EvalResult &Result, ConstExprUsage Usage, const ASTContext &Ctx) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression; EvalInfo Info(Ctx, Result, EM); Info.InConstantContext = true; if (!::Evaluate(Result.Val, Info, this)) return false; return CheckConstantExpression(Info, getExprLoc(), getType(), Result.Val, Usage); } bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, const VarDecl *VD, SmallVectorImpl &Notes) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); // FIXME: Evaluating initializers for large array and record types can cause // performance problems. Only do so in C++11 for now. if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && !Ctx.getLangOpts().CPlusPlus11) return false; Expr::EvalStatus EStatus; EStatus.Diag = &Notes; EvalInfo InitInfo(Ctx, EStatus, VD->isConstexpr() ? EvalInfo::EM_ConstantExpression : EvalInfo::EM_ConstantFold); InitInfo.setEvaluatingDecl(VD, Value); InitInfo.InConstantContext = true; LValue LVal; LVal.set(VD); // C++11 [basic.start.init]p2: // Variables with static storage duration or thread storage duration shall be // zero-initialized before any other initialization takes place. // This behavior is not present in C. if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() && !VD->getType()->isReferenceType()) { ImplicitValueInitExpr VIE(VD->getType()); if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE, /*AllowNonLiteralTypes=*/true)) return false; } if (!EvaluateInPlace(Value, InitInfo, LVal, this, /*AllowNonLiteralTypes=*/true) || EStatus.HasSideEffects) return false; return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(), Value); } /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be /// constant folded, but discard the result. bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalResult Result; return EvaluateAsRValue(Result, Ctx, /* in constant context */ true) && !hasUnacceptableSideEffect(Result, SEK); } APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx, SmallVectorImpl *Diag) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalResult EVResult; EVResult.Diag = Diag; EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); Info.InConstantContext = true; bool Result = ::EvaluateAsRValue(this, EVResult, Ctx, Info); (void)Result; assert(Result && "Could not evaluate expression"); assert(EVResult.Val.isInt() && "Expression did not evaluate to integer"); return EVResult.Val.getInt(); } APSInt Expr::EvaluateKnownConstIntCheckOverflow( const ASTContext &Ctx, SmallVectorImpl *Diag) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); EvalResult EVResult; EVResult.Diag = Diag; EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); Info.InConstantContext = true; Info.CheckingForUndefinedBehavior = true; bool Result = ::EvaluateAsRValue(Info, this, EVResult.Val); (void)Result; assert(Result && "Could not evaluate expression"); assert(EVResult.Val.isInt() && "Expression did not evaluate to integer"); return EVResult.Val.getInt(); } void Expr::EvaluateForOverflow(const ASTContext &Ctx) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); bool IsConst; EvalResult EVResult; if (!FastEvaluateAsRValue(this, EVResult, Ctx, IsConst)) { EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); Info.CheckingForUndefinedBehavior = true; (void)::EvaluateAsRValue(Info, this, EVResult.Val); } } bool Expr::EvalResult::isGlobalLValue() const { assert(Val.isLValue()); return IsGlobalLValue(Val.getLValueBase()); } /// isIntegerConstantExpr - this recursive routine will test if an expression is /// an integer constant expression. /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, /// comma, etc // CheckICE - This function does the fundamental ICE checking: the returned // ICEDiag contains an ICEKind indicating whether the expression is an ICE, // and a (possibly null) SourceLocation indicating the location of the problem. // // Note that to reduce code duplication, this helper does no evaluation // itself; the caller checks whether the expression is evaluatable, and // in the rare cases where CheckICE actually cares about the evaluated // value, it calls into Evaluate. namespace { enum ICEKind { /// This expression is an ICE. IK_ICE, /// This expression is not an ICE, but if it isn't evaluated, it's /// a legal subexpression for an ICE. This return value is used to handle /// the comma operator in C99 mode, and non-constant subexpressions. IK_ICEIfUnevaluated, /// This expression is not an ICE, and is not a legal subexpression for one. IK_NotICE }; struct ICEDiag { ICEKind Kind; SourceLocation Loc; ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {} }; } static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); } static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; } static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) { Expr::EvalResult EVResult; Expr::EvalStatus Status; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); Info.InConstantContext = true; if (!::EvaluateAsRValue(E, EVResult, Ctx, Info) || EVResult.HasSideEffects || !EVResult.Val.isInt()) return ICEDiag(IK_NotICE, E->getBeginLoc()); return NoDiag(); } static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) { assert(!E->isValueDependent() && "Should not see value dependent exprs!"); if (!E->getType()->isIntegralOrEnumerationType()) return ICEDiag(IK_NotICE, E->getBeginLoc()); switch (E->getStmtClass()) { #define ABSTRACT_STMT(Node) #define STMT(Node, Base) case Expr::Node##Class: #define EXPR(Node, Base) #include "clang/AST/StmtNodes.inc" case Expr::PredefinedExprClass: case Expr::FloatingLiteralClass: case Expr::ImaginaryLiteralClass: case Expr::StringLiteralClass: case Expr::ArraySubscriptExprClass: case Expr::OMPArraySectionExprClass: case Expr::MemberExprClass: case Expr::CompoundAssignOperatorClass: case Expr::CompoundLiteralExprClass: case Expr::ExtVectorElementExprClass: case Expr::DesignatedInitExprClass: case Expr::ArrayInitLoopExprClass: case Expr::ArrayInitIndexExprClass: case Expr::NoInitExprClass: case Expr::DesignatedInitUpdateExprClass: case Expr::ImplicitValueInitExprClass: case Expr::ParenListExprClass: case Expr::VAArgExprClass: case Expr::AddrLabelExprClass: case Expr::StmtExprClass: case Expr::CXXMemberCallExprClass: case Expr::CUDAKernelCallExprClass: case Expr::CXXDynamicCastExprClass: case Expr::CXXTypeidExprClass: case Expr::CXXUuidofExprClass: case Expr::MSPropertyRefExprClass: case Expr::MSPropertySubscriptExprClass: case Expr::CXXNullPtrLiteralExprClass: case Expr::UserDefinedLiteralClass: case Expr::CXXThisExprClass: case Expr::CXXThrowExprClass: case Expr::CXXNewExprClass: case Expr::CXXDeleteExprClass: case Expr::CXXPseudoDestructorExprClass: case Expr::UnresolvedLookupExprClass: case Expr::TypoExprClass: case Expr::DependentScopeDeclRefExprClass: case Expr::CXXConstructExprClass: case Expr::CXXInheritedCtorInitExprClass: case Expr::CXXStdInitializerListExprClass: case Expr::CXXBindTemporaryExprClass: case Expr::ExprWithCleanupsClass: case Expr::CXXTemporaryObjectExprClass: case Expr::CXXUnresolvedConstructExprClass: case Expr::CXXDependentScopeMemberExprClass: case Expr::UnresolvedMemberExprClass: case Expr::ObjCStringLiteralClass: case Expr::ObjCBoxedExprClass: case Expr::ObjCArrayLiteralClass: case Expr::ObjCDictionaryLiteralClass: case Expr::ObjCEncodeExprClass: case Expr::ObjCMessageExprClass: case Expr::ObjCSelectorExprClass: case Expr::ObjCProtocolExprClass: case Expr::ObjCIvarRefExprClass: case Expr::ObjCPropertyRefExprClass: case Expr::ObjCSubscriptRefExprClass: case Expr::ObjCIsaExprClass: case Expr::ObjCAvailabilityCheckExprClass: case Expr::ShuffleVectorExprClass: case Expr::ConvertVectorExprClass: case Expr::BlockExprClass: case Expr::NoStmtClass: case Expr::OpaqueValueExprClass: case Expr::PackExpansionExprClass: case Expr::SubstNonTypeTemplateParmPackExprClass: case Expr::FunctionParmPackExprClass: case Expr::AsTypeExprClass: case Expr::ObjCIndirectCopyRestoreExprClass: case Expr::MaterializeTemporaryExprClass: case Expr::PseudoObjectExprClass: case Expr::AtomicExprClass: case Expr::LambdaExprClass: case Expr::CXXFoldExprClass: case Expr::CoawaitExprClass: case Expr::DependentCoawaitExprClass: case Expr::CoyieldExprClass: return ICEDiag(IK_NotICE, E->getBeginLoc()); case Expr::InitListExprClass: { // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the // form "T x = { a };" is equivalent to "T x = a;". // Unless we're initializing a reference, T is a scalar as it is known to be // of integral or enumeration type. if (E->isRValue()) if (cast(E)->getNumInits() == 1) return CheckICE(cast(E)->getInit(0), Ctx); return ICEDiag(IK_NotICE, E->getBeginLoc()); } case Expr::SizeOfPackExprClass: case Expr::GNUNullExprClass: case Expr::SourceLocExprClass: return NoDiag(); case Expr::SubstNonTypeTemplateParmExprClass: return CheckICE(cast(E)->getReplacement(), Ctx); case Expr::ConstantExprClass: return CheckICE(cast(E)->getSubExpr(), Ctx); case Expr::ParenExprClass: return CheckICE(cast(E)->getSubExpr(), Ctx); case Expr::GenericSelectionExprClass: return CheckICE(cast(E)->getResultExpr(), Ctx); case Expr::IntegerLiteralClass: case Expr::FixedPointLiteralClass: case Expr::CharacterLiteralClass: case Expr::ObjCBoolLiteralExprClass: case Expr::CXXBoolLiteralExprClass: case Expr::CXXScalarValueInitExprClass: case Expr::TypeTraitExprClass: case Expr::ArrayTypeTraitExprClass: case Expr::ExpressionTraitExprClass: case Expr::CXXNoexceptExprClass: return NoDiag(); case Expr::CallExprClass: case Expr::CXXOperatorCallExprClass: { // C99 6.6/3 allows function calls within unevaluated subexpressions of // constant expressions, but they can never be ICEs because an ICE cannot // contain an operand of (pointer to) function type. const CallExpr *CE = cast(E); if (CE->getBuiltinCallee()) return CheckEvalInICE(E, Ctx); return ICEDiag(IK_NotICE, E->getBeginLoc()); } case Expr::DeclRefExprClass: { if (isa(cast(E)->getDecl())) return NoDiag(); const ValueDecl *D = cast(E)->getDecl(); if (Ctx.getLangOpts().CPlusPlus && D && IsConstNonVolatile(D->getType())) { // Parameter variables are never constants. Without this check, // getAnyInitializer() can find a default argument, which leads // to chaos. if (isa(D)) return ICEDiag(IK_NotICE, cast(E)->getLocation()); // C++ 7.1.5.1p2 // A variable of non-volatile const-qualified integral or enumeration // type initialized by an ICE can be used in ICEs. if (const VarDecl *Dcl = dyn_cast(D)) { if (!Dcl->getType()->isIntegralOrEnumerationType()) return ICEDiag(IK_NotICE, cast(E)->getLocation()); const VarDecl *VD; // Look for a declaration of this variable that has an initializer, and // check whether it is an ICE. if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE()) return NoDiag(); else return ICEDiag(IK_NotICE, cast(E)->getLocation()); } } return ICEDiag(IK_NotICE, E->getBeginLoc()); } case Expr::UnaryOperatorClass: { const UnaryOperator *Exp = cast(E); switch (Exp->getOpcode()) { case UO_PostInc: case UO_PostDec: case UO_PreInc: case UO_PreDec: case UO_AddrOf: case UO_Deref: case UO_Coawait: // C99 6.6/3 allows increment and decrement within unevaluated // subexpressions of constant expressions, but they can never be ICEs // because an ICE cannot contain an lvalue operand. return ICEDiag(IK_NotICE, E->getBeginLoc()); case UO_Extension: case UO_LNot: case UO_Plus: case UO_Minus: case UO_Not: case UO_Real: case UO_Imag: return CheckICE(Exp->getSubExpr(), Ctx); } llvm_unreachable("invalid unary operator class"); } case Expr::OffsetOfExprClass: { // Note that per C99, offsetof must be an ICE. And AFAIK, using // EvaluateAsRValue matches the proposed gcc behavior for cases like // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect // compliance: we should warn earlier for offsetof expressions with // array subscripts that aren't ICEs, and if the array subscripts // are ICEs, the value of the offsetof must be an integer constant. return CheckEvalInICE(E, Ctx); } case Expr::UnaryExprOrTypeTraitExprClass: { const UnaryExprOrTypeTraitExpr *Exp = cast(E); if ((Exp->getKind() == UETT_SizeOf) && Exp->getTypeOfArgument()->isVariableArrayType()) return ICEDiag(IK_NotICE, E->getBeginLoc()); return NoDiag(); } case Expr::BinaryOperatorClass: { const BinaryOperator *Exp = cast(E); switch (Exp->getOpcode()) { case BO_PtrMemD: case BO_PtrMemI: case BO_Assign: case BO_MulAssign: case BO_DivAssign: case BO_RemAssign: case BO_AddAssign: case BO_SubAssign: case BO_ShlAssign: case BO_ShrAssign: case BO_AndAssign: case BO_XorAssign: case BO_OrAssign: // C99 6.6/3 allows assignments within unevaluated subexpressions of // constant expressions, but they can never be ICEs because an ICE cannot // contain an lvalue operand. return ICEDiag(IK_NotICE, E->getBeginLoc()); case BO_Mul: case BO_Div: case BO_Rem: case BO_Add: case BO_Sub: case BO_Shl: case BO_Shr: case BO_LT: case BO_GT: case BO_LE: case BO_GE: case BO_EQ: case BO_NE: case BO_And: case BO_Xor: case BO_Or: case BO_Comma: case BO_Cmp: { ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); if (Exp->getOpcode() == BO_Div || Exp->getOpcode() == BO_Rem) { // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure // we don't evaluate one. if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) { llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); if (REval == 0) return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); if (REval.isSigned() && REval.isAllOnesValue()) { llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); if (LEval.isMinSignedValue()) return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); } } } if (Exp->getOpcode() == BO_Comma) { if (Ctx.getLangOpts().C99) { // C99 6.6p3 introduces a strange edge case: comma can be in an ICE // if it isn't evaluated. if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); } else { // In both C89 and C++, commas in ICEs are illegal. return ICEDiag(IK_NotICE, E->getBeginLoc()); } } return Worst(LHSResult, RHSResult); } case BO_LAnd: case BO_LOr: { ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) { // Rare case where the RHS has a comma "side-effect"; we need // to actually check the condition to see whether the side // with the comma is evaluated. if ((Exp->getOpcode() == BO_LAnd) != (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) return RHSResult; return NoDiag(); } return Worst(LHSResult, RHSResult); } } llvm_unreachable("invalid binary operator kind"); } case Expr::ImplicitCastExprClass: case Expr::CStyleCastExprClass: case Expr::CXXFunctionalCastExprClass: case Expr::CXXStaticCastExprClass: case Expr::CXXReinterpretCastExprClass: case Expr::CXXConstCastExprClass: case Expr::ObjCBridgedCastExprClass: { const Expr *SubExpr = cast(E)->getSubExpr(); if (isa(E)) { if (const FloatingLiteral *FL = dyn_cast(SubExpr->IgnoreParenImpCasts())) { unsigned DestWidth = Ctx.getIntWidth(E->getType()); bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); APSInt IgnoredVal(DestWidth, !DestSigned); bool Ignored; // If the value does not fit in the destination type, the behavior is // undefined, so we are not required to treat it as a constant // expression. if (FL->getValue().convertToInteger(IgnoredVal, llvm::APFloat::rmTowardZero, &Ignored) & APFloat::opInvalidOp) return ICEDiag(IK_NotICE, E->getBeginLoc()); return NoDiag(); } } switch (cast(E)->getCastKind()) { case CK_LValueToRValue: case CK_AtomicToNonAtomic: case CK_NonAtomicToAtomic: case CK_NoOp: case CK_IntegralToBoolean: case CK_IntegralCast: return CheckICE(SubExpr, Ctx); default: return ICEDiag(IK_NotICE, E->getBeginLoc()); } } case Expr::BinaryConditionalOperatorClass: { const BinaryConditionalOperator *Exp = cast(E); ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); if (CommonResult.Kind == IK_NotICE) return CommonResult; ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); if (FalseResult.Kind == IK_NotICE) return FalseResult; if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult; if (FalseResult.Kind == IK_ICEIfUnevaluated && Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag(); return FalseResult; } case Expr::ConditionalOperatorClass: { const ConditionalOperator *Exp = cast(E); // If the condition (ignoring parens) is a __builtin_constant_p call, // then only the true side is actually considered in an integer constant // expression, and it is fully evaluated. This is an important GNU // extension. See GCC PR38377 for discussion. if (const CallExpr *CallCE = dyn_cast(Exp->getCond()->IgnoreParenCasts())) if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) return CheckEvalInICE(E, Ctx); ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); if (CondResult.Kind == IK_NotICE) return CondResult; ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); if (TrueResult.Kind == IK_NotICE) return TrueResult; if (FalseResult.Kind == IK_NotICE) return FalseResult; if (CondResult.Kind == IK_ICEIfUnevaluated) return CondResult; if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE) return NoDiag(); // Rare case where the diagnostics depend on which side is evaluated // Note that if we get here, CondResult is 0, and at least one of // TrueResult and FalseResult is non-zero. if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) return FalseResult; return TrueResult; } case Expr::CXXDefaultArgExprClass: return CheckICE(cast(E)->getExpr(), Ctx); case Expr::CXXDefaultInitExprClass: return CheckICE(cast(E)->getExpr(), Ctx); case Expr::ChooseExprClass: { return CheckICE(cast(E)->getChosenSubExpr(), Ctx); } case Expr::BuiltinBitCastExprClass: { if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast(E))) return ICEDiag(IK_NotICE, E->getBeginLoc()); return CheckICE(cast(E)->getSubExpr(), Ctx); } } llvm_unreachable("Invalid StmtClass!"); } /// Evaluate an expression as a C++11 integral constant expression. static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx, const Expr *E, llvm::APSInt *Value, SourceLocation *Loc) { if (!E->getType()->isIntegralOrUnscopedEnumerationType()) { if (Loc) *Loc = E->getExprLoc(); return false; } APValue Result; if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) return false; if (!Result.isInt()) { if (Loc) *Loc = E->getExprLoc(); return false; } if (Value) *Value = Result.getInt(); return true; } bool Expr::isIntegerConstantExpr(const ASTContext &Ctx, SourceLocation *Loc) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); if (Ctx.getLangOpts().CPlusPlus11) return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc); ICEDiag D = CheckICE(this, Ctx); if (D.Kind != IK_ICE) { if (Loc) *Loc = D.Loc; return false; } return true; } bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, const ASTContext &Ctx, SourceLocation *Loc, bool isEvaluated) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); if (Ctx.getLangOpts().CPlusPlus11) return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); if (!isIntegerConstantExpr(Ctx, Loc)) return false; // The only possible side-effects here are due to UB discovered in the // evaluation (for instance, INT_MAX + 1). In such a case, we are still // required to treat the expression as an ICE, so we produce the folded // value. EvalResult ExprResult; Expr::EvalStatus Status; EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects); Info.InConstantContext = true; if (!::EvaluateAsInt(this, ExprResult, Ctx, SE_AllowSideEffects, Info)) llvm_unreachable("ICE cannot be evaluated!"); Value = ExprResult.Val.getInt(); return true; } bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); return CheckICE(this, Ctx).Kind == IK_ICE; } bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result, SourceLocation *Loc) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); // We support this checking in C++98 mode in order to diagnose compatibility // issues. assert(Ctx.getLangOpts().CPlusPlus); // Build evaluation settings. Expr::EvalStatus Status; SmallVector Diags; Status.Diag = &Diags; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); APValue Scratch; bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch); if (!Diags.empty()) { IsConstExpr = false; if (Loc) *Loc = Diags[0].first; } else if (!IsConstExpr) { // FIXME: This shouldn't happen. if (Loc) *Loc = getExprLoc(); } return IsConstExpr; } bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx, const FunctionDecl *Callee, ArrayRef Args, const Expr *This) const { assert(!isValueDependent() && "Expression evaluator can't be called on a dependent expression."); Expr::EvalStatus Status; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated); Info.InConstantContext = true; LValue ThisVal; const LValue *ThisPtr = nullptr; if (This) { #ifndef NDEBUG auto *MD = dyn_cast(Callee); assert(MD && "Don't provide `this` for non-methods."); assert(!MD->isStatic() && "Don't provide `this` for static methods."); #endif if (EvaluateObjectArgument(Info, This, ThisVal)) ThisPtr = &ThisVal; if (Info.EvalStatus.HasSideEffects) return false; } ArgVector ArgValues(Args.size()); for (ArrayRef::iterator I = Args.begin(), E = Args.end(); I != E; ++I) { if ((*I)->isValueDependent() || !Evaluate(ArgValues[I - Args.begin()], Info, *I)) // If evaluation fails, throw away the argument entirely. ArgValues[I - Args.begin()] = APValue(); if (Info.EvalStatus.HasSideEffects) return false; } // Build fake call to Callee. CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, ArgValues.data()); return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects; } bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, SmallVectorImpl< PartialDiagnosticAt> &Diags) { // FIXME: It would be useful to check constexpr function templates, but at the // moment the constant expression evaluator cannot cope with the non-rigorous // ASTs which we build for dependent expressions. if (FD->isDependentContext()) return true; Expr::EvalStatus Status; Status.Diag = &Diags; EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression); Info.InConstantContext = true; Info.CheckingPotentialConstantExpression = true; const CXXMethodDecl *MD = dyn_cast(FD); const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr; // Fabricate an arbitrary expression on the stack and pretend that it // is a temporary being used as the 'this' pointer. LValue This; ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); This.set({&VIE, Info.CurrentCall->Index}); ArrayRef Args; APValue Scratch; if (const CXXConstructorDecl *CD = dyn_cast(FD)) { // Evaluate the call as a constant initializer, to allow the construction // of objects of non-literal types. Info.setEvaluatingDecl(This.getLValueBase(), Scratch); HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch); } else { SourceLocation Loc = FD->getLocation(); HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr, Args, FD->getBody(), Info, Scratch, nullptr); } return Diags.empty(); } bool Expr::isPotentialConstantExprUnevaluated(Expr *E, const FunctionDecl *FD, SmallVectorImpl< PartialDiagnosticAt> &Diags) { assert(!E->isValueDependent() && "Expression evaluator can't be called on a dependent expression."); Expr::EvalStatus Status; Status.Diag = &Diags; EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpressionUnevaluated); Info.InConstantContext = true; Info.CheckingPotentialConstantExpression = true; // Fabricate a call stack frame to give the arguments a plausible cover story. ArrayRef Args; ArgVector ArgValues(0); bool Success = EvaluateArgs(Args, ArgValues, Info, FD); (void)Success; assert(Success && "Failed to set up arguments for potential constant evaluation"); CallStackFrame Frame(Info, SourceLocation(), FD, nullptr, ArgValues.data()); APValue ResultScratch; Evaluate(ResultScratch, Info, E); return Diags.empty(); } bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx, unsigned Type) const { if (!getType()->isPointerType()) return false; Expr::EvalStatus Status; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); return tryEvaluateBuiltinObjectSize(this, Type, Info, Result); }