//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // 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 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/CharUnits.h" #include "clang/AST/RecordLayout.h" #include "clang/AST/StmtVisitor.h" #include "clang/AST/TypeLoc.h" #include "clang/AST/ASTDiagnostic.h" #include "clang/AST/Expr.h" #include "clang/Basic/Builtins.h" #include "clang/Basic/TargetInfo.h" #include "llvm/ADT/SmallString.h" #include #include using namespace clang; using llvm::APSInt; using llvm::APFloat; static bool IsGlobalLValue(APValue::LValueBase B); namespace { struct LValue; struct CallStackFrame; struct EvalInfo; static QualType getType(APValue::LValueBase B) { if (!B) return QualType(); if (const ValueDecl *D = B.dyn_cast()) return D->getType(); return B.get()->getType(); } /// Get an LValue path entry, which is known to not be an array index, as a /// field or base class. static APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) { APValue::BaseOrMemberType Value; Value.setFromOpaqueValue(E.BaseOrMember); return Value; } /// 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(getAsBaseOrMember(E).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(getAsBaseOrMember(E).getPointer()); } /// Determine whether this LValue path entry for a base class names a virtual /// base class. static bool isVirtualBaseClass(APValue::LValuePathEntry E) { return getAsBaseOrMember(E).getInt(); } /// 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, QualType Base, ArrayRef Path, uint64_t &ArraySize, QualType &Type) { unsigned MostDerivedLength = 0; Type = Base; for (unsigned I = 0, N = Path.size(); I != N; ++I) { if (Type->isArrayType()) { const ConstantArrayType *CAT = cast(Ctx.getAsArrayType(Type)); Type = CAT->getElementType(); ArraySize = CAT->getSize().getZExtValue(); MostDerivedLength = I + 1; } else if (Type->isAnyComplexType()) { const ComplexType *CT = Type->castAs(); Type = CT->getElementType(); ArraySize = 2; MostDerivedLength = I + 1; } else if (const FieldDecl *FD = getAsField(Path[I])) { Type = FD->getType(); ArraySize = 0; MostDerivedLength = I + 1; } else { // Path[I] describes a base class. ArraySize = 0; } } return MostDerivedLength; } // The order of this enum is important for diagnostics. enum CheckSubobjectKind { CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex, CSK_This, 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. bool Invalid : 1; /// Is this a pointer one past the end of an object? bool IsOnePastTheEnd : 1; /// The length of the path to the most-derived object of which this is a /// subobject. unsigned MostDerivedPathLength : 30; /// The size of the array of which the most-derived object is an element, or /// 0 if the most-derived object is not an array element. 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), MostDerivedPathLength(0), MostDerivedArraySize(0), MostDerivedType(T) {} SubobjectDesignator(ASTContext &Ctx, const APValue &V) : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), MostDerivedPathLength(0), MostDerivedArraySize(0) { if (!Invalid) { IsOnePastTheEnd = V.isLValueOnePastTheEnd(); ArrayRef VEntries = V.getLValuePath(); Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); if (V.getLValueBase()) MostDerivedPathLength = findMostDerivedSubobject(Ctx, getType(V.getLValueBase()), V.getLValuePath(), MostDerivedArraySize, MostDerivedType); } } void setInvalid() { Invalid = true; Entries.clear(); } /// Determine whether this is a one-past-the-end pointer. bool isOnePastTheEnd() const { if (IsOnePastTheEnd) return true; if (MostDerivedArraySize && Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize) return true; return false; } /// 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); /// Update this designator to refer to the first element within this array. void addArrayUnchecked(const ConstantArrayType *CAT) { PathEntry Entry; Entry.ArrayIndex = 0; Entries.push_back(Entry); // This is a most-derived object. MostDerivedType = CAT->getElementType(); MostDerivedArraySize = CAT->getSize().getZExtValue(); 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) { PathEntry Entry; APValue::BaseOrMemberType Value(D, Virtual); Entry.BaseOrMember = Value.getOpaqueValue(); Entries.push_back(Entry); // If this isn't a base class, it's a new most-derived object. if (const FieldDecl *FD = dyn_cast(D)) { MostDerivedType = FD->getType(); MostDerivedArraySize = 0; MostDerivedPathLength = Entries.size(); } } /// Update this designator to refer to the given complex component. void addComplexUnchecked(QualType EltTy, bool Imag) { PathEntry Entry; Entry.ArrayIndex = Imag; Entries.push_back(Entry); // This is technically a most-derived object, though in practice this // is unlikely to matter. MostDerivedType = EltTy; MostDerivedArraySize = 2; MostDerivedPathLength = Entries.size(); } void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, uint64_t N); /// Add N to the address of this subobject. void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { if (Invalid) return; if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) { Entries.back().ArrayIndex += N; if (Entries.back().ArrayIndex > MostDerivedArraySize) { diagnosePointerArithmetic(Info, E, Entries.back().ArrayIndex); setInvalid(); } 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. if (IsOnePastTheEnd && N == (uint64_t)-1) IsOnePastTheEnd = false; else if (!IsOnePastTheEnd && N == 1) IsOnePastTheEnd = true; else if (N != 0) { diagnosePointerArithmetic(Info, E, uint64_t(IsOnePastTheEnd) + N); setInvalid(); } } }; /// A stack frame in the constexpr call stack. struct CallStackFrame { EvalInfo &Info; /// Parent - The caller of this stack frame. CallStackFrame *Caller; /// CallLoc - The location of the call expression for this call. SourceLocation CallLoc; /// Callee - The function which was called. const FunctionDecl *Callee; /// Index - The call index of this call. unsigned Index; /// This - The binding for the this pointer in this call, if any. const LValue *This; /// ParmBindings - Parameter bindings for this function call, indexed by /// parameters' function scope indices. const APValue *Arguments; typedef llvm::DenseMap MapTy; typedef MapTy::const_iterator temp_iterator; /// Temporaries - Temporary lvalues materialized within this stack frame. MapTy Temporaries; CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, const APValue *Arguments); ~CallStackFrame(); }; /// 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 = 0) : Diag(Diag) {} template OptionalDiagnostic &operator<<(const T &v) { if (Diag) *Diag << v; return *this; } OptionalDiagnostic &operator<<(const APSInt &I) { if (Diag) { llvm::SmallVector Buffer; I.toString(Buffer); *Diag << StringRef(Buffer.data(), Buffer.size()); } return *this; } OptionalDiagnostic &operator<<(const APFloat &F) { if (Diag) { llvm::SmallVector Buffer; F.toString(Buffer); *Diag << StringRef(Buffer.data(), Buffer.size()); } return *this; } }; /// 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; typedef llvm::DenseMap MapTy; /// OpaqueValues - Values used as the common expression in a /// BinaryConditionalOperator. MapTy OpaqueValues; /// BottomFrame - The frame in which evaluation started. This must be /// initialized after CurrentCall and CallStackDepth. CallStackFrame BottomFrame; /// EvaluatingDecl - This is the declaration whose initializer is being /// evaluated, if any. const VarDecl *EvaluatingDecl; /// EvaluatingDeclValue - This is the value being constructed for the /// declaration whose initializer is being evaluated, if any. APValue *EvaluatingDeclValue; /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further /// notes attached to it will also be stored, otherwise they will not be. bool HasActiveDiagnostic; /// CheckingPotentialConstantExpression - Are we checking whether the /// expression is a potential constant expression? If so, some diagnostics /// are suppressed. bool CheckingPotentialConstantExpression; EvalInfo(const ASTContext &C, Expr::EvalStatus &S) : Ctx(const_cast(C)), EvalStatus(S), CurrentCall(0), CallStackDepth(0), NextCallIndex(1), BottomFrame(*this, SourceLocation(), 0, 0, 0), EvaluatingDecl(0), EvaluatingDeclValue(0), HasActiveDiagnostic(false), CheckingPotentialConstantExpression(false) {} const APValue *getOpaqueValue(const OpaqueValueExpr *e) const { MapTy::const_iterator i = OpaqueValues.find(e); if (i == OpaqueValues.end()) return 0; return &i->second; } void setEvaluatingDecl(const VarDecl *VD, APValue &Value) { EvaluatingDecl = VD; 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. Diag(Loc, diag::note_constexpr_call_limit_exceeded); return false; } if (CallStackDepth <= getLangOpts().ConstexprCallDepth) return true; Diag(Loc, diag::note_constexpr_depth_limit_exceeded) << getLangOpts().ConstexprCallDepth; return false; } CallStackFrame *getCallFrame(unsigned CallIndex) { assert(CallIndex && "no call index in getCallFrame"); // We will eventually hit BottomFrame, which has Index 1, so Frame can't // be null in this loop. CallStackFrame *Frame = CurrentCall; while (Frame->Index > CallIndex) Frame = Frame->Caller; return (Frame->Index == CallIndex) ? Frame : 0; } 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); public: /// Diagnose that the evaluation cannot be folded. OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { // If we have a prior diagnostic, it will be noting that the expression // isn't a constant expression. This diagnostic is more important. // FIXME: We might want to show both diagnostics to the user. if (EvalStatus.Diag) { unsigned CallStackNotes = CallStackDepth - 1; unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); if (Limit) CallStackNotes = std::min(CallStackNotes, Limit + 1); if (CheckingPotentialConstantExpression) CallStackNotes = 0; HasActiveDiagnostic = true; 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(); } OptionalDiagnostic Diag(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); HasActiveDiagnostic = false; return OptionalDiagnostic(); } /// Diagnose that the evaluation does not produce a C++11 core constant /// expression. template OptionalDiagnostic CCEDiag(LocArg Loc, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { // Don't override a previous diagnostic. if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { HasActiveDiagnostic = false; return OptionalDiagnostic(); } return Diag(Loc, 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 as much as possible after encountering a /// construct which can't be folded? bool keepEvaluatingAfterFailure() { return CheckingPotentialConstantExpression && EvalStatus.Diag && EvalStatus.Diag->empty(); } }; /// Object used to treat all foldable expressions as constant expressions. struct FoldConstant { bool Enabled; explicit FoldConstant(EvalInfo &Info) : Enabled(Info.EvalStatus.Diag && Info.EvalStatus.Diag->empty() && !Info.EvalStatus.HasSideEffects) { } // Treat the value we've computed since this object was created as constant. void Fold(EvalInfo &Info) { if (Enabled && !Info.EvalStatus.Diag->empty() && !Info.EvalStatus.HasSideEffects) Info.EvalStatus.Diag->clear(); } }; /// RAII object used to suppress diagnostics and side-effects from a /// speculative evaluation. class SpeculativeEvaluationRAII { EvalInfo &Info; Expr::EvalStatus Old; public: SpeculativeEvaluationRAII(EvalInfo &Info, llvm::SmallVectorImpl *NewDiag = 0) : Info(Info), Old(Info.EvalStatus) { Info.EvalStatus.Diag = NewDiag; } ~SpeculativeEvaluationRAII() { Info.EvalStatus = Old; } }; } 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; } return true; } void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, uint64_t N) { if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) Info.CCEDiag(E, diag::note_constexpr_array_index) << static_cast(N) << /*array*/ 0 << static_cast(MostDerivedArraySize); else Info.CCEDiag(E, diag::note_constexpr_array_index) << static_cast(N) << /*non-array*/ 1; setInvalid(); } CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, const APValue *Arguments) : Info(Info), Caller(Info.CurrentCall), CallLoc(CallLoc), Callee(Callee), Index(Info.NextCallIndex++), This(This), Arguments(Arguments) { Info.CurrentCall = this; ++Info.CallStackDepth; } CallStackFrame::~CallStackFrame() { assert(Info.CurrentCall == this && "calls retired out of order"); --Info.CallStackDepth; Info.CurrentCall = Caller; } /// Produce a string describing the given constexpr call. static void describeCall(CallStackFrame *Frame, llvm::raw_ostream &Out) { unsigned ArgIndex = 0; bool IsMemberCall = isa(Frame->Callee) && !isa(Frame->Callee) && cast(Frame->Callee)->isInstance(); if (!IsMemberCall) Out << *Frame->Callee << '('; 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 << ')'; } 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; } llvm::SmallVector Buffer; llvm::raw_svector_ostream Out(Buffer); describeCall(Frame, Out); addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); } } 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; unsigned CallIndex; SubobjectDesignator Designator; const APValue::LValueBase getLValueBase() const { return Base; } CharUnits &getLValueOffset() { return Offset; } const CharUnits &getLValueOffset() const { return Offset; } unsigned getLValueCallIndex() const { return CallIndex; } SubobjectDesignator &getLValueDesignator() { return Designator; } const SubobjectDesignator &getLValueDesignator() const { return Designator;} void moveInto(APValue &V) const { if (Designator.Invalid) V = APValue(Base, Offset, APValue::NoLValuePath(), CallIndex); else V = APValue(Base, Offset, Designator.Entries, Designator.IsOnePastTheEnd, CallIndex); } void setFrom(ASTContext &Ctx, const APValue &V) { assert(V.isLValue()); Base = V.getLValueBase(); Offset = V.getLValueOffset(); CallIndex = V.getLValueCallIndex(); Designator = SubobjectDesignator(Ctx, V); } void set(APValue::LValueBase B, unsigned I = 0) { Base = B; Offset = CharUnits::Zero(); CallIndex = I; Designator = SubobjectDesignator(getType(B)); } // Check that this LValue is not based on a null pointer. If it is, produce // a diagnostic and mark the designator as invalid. bool checkNullPointer(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { if (Designator.Invalid) return false; if (!Base) { Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK; Designator.setInvalid(); return false; } return true; } // 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) { // Outside C++11, do not build a designator referring to a subobject of // any object: we won't use such a designator for anything. if (!Info.getLangOpts().CPlusPlus0x) Designator.setInvalid(); return 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 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 adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { if (checkNullPointer(Info, E, CSK_ArrayIndex)) Designator.adjustIndex(Info, E, N); } }; 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; } /// Kinds of constant expression checking, for diagnostics. enum CheckConstantExpressionKind { CCEK_Constant, ///< A normal constant. CCEK_ReturnValue, ///< A constexpr function return value. CCEK_MemberInit ///< A constexpr constructor mem-initializer. }; } static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, const Expr *E, CheckConstantExpressionKind CCEK = CCEK_Constant, bool AllowNonLiteralTypes = false); static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info); static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info); 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); //===----------------------------------------------------------------------===// // Misc utilities //===----------------------------------------------------------------------===// /// Should this call expression be treated as a string literal? static bool IsStringLiteralCall(const CallExpr *E) { unsigned Builtin = E->isBuiltinCall(); 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); } const Expr *E = B.get(); switch (E->getStmtClass()) { default: return false; case Expr::CompoundLiteralExprClass: { const CompoundLiteralExpr *CLE = cast(E); return CLE->isFileScope() && CLE->isLValue(); } // A string literal has static storage duration. case Expr::StringLiteralClass: case Expr::PredefinedExprClass: case Expr::ObjCStringLiteralClass: case Expr::ObjCEncodeExprClass: case Expr::CXXTypeidExprClass: case Expr::CXXUuidofExprClass: return true; 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 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 Info.Note(Base.dyn_cast()->getExprLoc(), diag::note_constexpr_temporary_here); } /// 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) { 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().CPlusPlus0x) { const ValueDecl *VD = Base.dyn_cast(); Info.Diag(Loc, diag::note_constexpr_non_global, 1) << IsReferenceType << !Designator.Entries.empty() << !!VD << VD; NoteLValueLocation(Info, Base); } else { Info.Diag(Loc); } // Don't allow references to temporaries to escape. return false; } assert((Info.CheckingPotentialConstantExpression || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"); // 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.isOnePastTheEnd()) { const ValueDecl *VD = Base.dyn_cast(); Info.Diag(Loc, diag::note_constexpr_past_end, 1) << !Designator.Entries.empty() << !!VD << VD; NoteLValueLocation(Info, Base); } return true; } /// 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) { if (!E->isRValue() || E->getType()->isLiteralType()) return true; // Prvalue constant expressions must be of literal types. if (Info.getLangOpts().CPlusPlus0x) Info.Diag(E, diag::note_constexpr_nonliteral) << E->getType(); else Info.Diag(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) { // 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))) return false; } if (!Value.hasArrayFiller()) return true; return CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayFiller()); } if (Value.isUnion() && Value.getUnionField()) { return CheckConstantExpression(Info, DiagLoc, Value.getUnionField()->getType(), Value.getUnionValue()); } if (Value.isStruct()) { RecordDecl *RD = Type->castAs()->getDecl(); if (const CXXRecordDecl *CD = dyn_cast(RD)) { unsigned BaseIndex = 0; for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), End = CD->bases_end(); I != End; ++I, ++BaseIndex) { if (!CheckConstantExpression(Info, DiagLoc, I->getType(), Value.getStructBase(BaseIndex))) return false; } } for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); I != E; ++I) { if (!CheckConstantExpression(Info, DiagLoc, (*I)->getType(), Value.getStructField((*I)->getFieldIndex()))) return false; } } if (Value.isLValue()) { LValue LVal; LVal.setFrom(Info.Ctx, Value); return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal); } // Everything else is fine. return true; } const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { return LVal.Base.dyn_cast(); } static bool IsLiteralLValue(const LValue &Value) { return Value.Base.dyn_cast() && !Value.CallIndex; } static bool IsWeakLValue(const LValue &Value) { const ValueDecl *Decl = GetLValueBaseDecl(Value); return Decl && Decl->isWeak(); } 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::Uninitialized: return false; case APValue::Int: Result = Val.getInt().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.Diag(E, diag::note_constexpr_overflow) << SrcValue << DestType; return false; } 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; if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), APFloat::rmNearestTiesToEven, &ignored) & APFloat::opOverflow) return HandleOverflow(Info, E, Value, DestType); return true; } static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, QualType DestType, QualType SrcType, APSInt &Value) { unsigned DestWidth = Info.Ctx.getIntWidth(DestType); APSInt Result = Value; // Figure out if this is a truncate, extend or noop cast. // If the input is signed, do a sign extend, noop, or truncate. Result = Result.extOrTrunc(DestWidth); Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); 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); if (Result.convertFromAPInt(Value, Value.isSigned(), APFloat::rmNearestTiesToEven) & APFloat::opOverflow) return HandleOverflow(Info, E, Value, DestType); 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.Diag(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.Diag(E, diag::note_invalid_subexpr_in_const_expr); return false; } /// 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) { 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 void HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, const CXXRecordDecl *Derived, const CXXRecordDecl *Base, const ASTRecordLayout *RL = 0) { if (!RL) RL = &Info.Ctx.getASTRecordLayout(Derived); Obj.getLValueOffset() += RL->getBaseClassOffset(Base); Obj.addDecl(Info, E, Base, /*Virtual*/ false); } 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()) { HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); return true; } 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. const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); return true; } /// Update LVal to refer to the given field, which must be a member of the type /// currently described by LVal. static void HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, const FieldDecl *FD, const ASTRecordLayout *RL = 0) { if (!RL) RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); unsigned I = FD->getFieldIndex(); LVal.Offset += Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)); LVal.addDecl(Info, E, FD); } /// Update LVal to refer to the given indirect field. static void HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, LValue &LVal, const IndirectFieldDecl *IFD) { for (IndirectFieldDecl::chain_iterator C = IFD->chain_begin(), CE = IFD->chain_end(); C != CE; ++C) HandleLValueMember(Info, E, LVal, cast(*C)); } /// 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->isConstantSizeType()) { // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. // FIXME: Better diagnostic. Info.Diag(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, int64_t Adjustment) { CharUnits SizeOfPointee; if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) return false; // Compute the new offset in the appropriate width. LVal.Offset += Adjustment * SizeOfPointee; LVal.adjustIndex(Info, E, Adjustment); return true; } /// 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. static bool EvaluateVarDeclInit(EvalInfo &Info, const Expr *E, const VarDecl *VD, CallStackFrame *Frame, APValue &Result) { // 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.Diag(E, diag::note_invalid_subexpr_in_const_expr); return false; } Result = Frame->Arguments[PVD->getFunctionScopeIndex()]; 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.Diag(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 == VD) { Result = *Info.EvaluatingDeclValue; return !Result.isUninit(); } // 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.Diag(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. llvm::SmallVector Notes; if (!VD->evaluateValue(Notes)) { Info.Diag(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. CharType is used to /// determine the expected signedness of the result -- a string literal used to /// initialize an array of 'signed char' or 'unsigned char' might contain chars /// of the wrong signedness. static APSInt ExtractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, uint64_t Index, QualType CharType) { // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant const StringLiteral *S = dyn_cast(Lit); assert(S && "unexpected string literal expression kind"); 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; } /// Extract the designated sub-object of an rvalue. static bool ExtractSubobject(EvalInfo &Info, const Expr *E, APValue &Obj, QualType ObjType, const SubobjectDesignator &Sub, QualType SubType) { if (Sub.Invalid) // A diagnostic will have already been produced. return false; if (Sub.isOnePastTheEnd()) { Info.Diag(E, Info.getLangOpts().CPlusPlus0x ? (unsigned)diag::note_constexpr_read_past_end : (unsigned)diag::note_invalid_subexpr_in_const_expr); return false; } if (Sub.Entries.empty()) return true; if (Info.CheckingPotentialConstantExpression && Obj.isUninit()) // This object might be initialized later. return false; APValue *O = &Obj; // Walk the designator's path to find the subobject. for (unsigned I = 0, N = Sub.Entries.size(); I != N; ++I) { 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].ArrayIndex; 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. Info.Diag(E, Info.getLangOpts().CPlusPlus0x ? (unsigned)diag::note_constexpr_read_past_end : (unsigned)diag::note_invalid_subexpr_in_const_expr); return false; } // An array object is represented as either an Array APValue or as an // LValue which refers to a string literal. if (O->isLValue()) { assert(I == N - 1 && "extracting subobject of character?"); assert(!O->hasLValuePath() || O->getLValuePath().empty()); Obj = APValue(ExtractStringLiteralCharacter( Info, O->getLValueBase().get(), Index, SubType)); return true; } else if (O->getArrayInitializedElts() > Index) O = &O->getArrayInitializedElt(Index); else O = &O->getArrayFiller(); ObjType = CAT->getElementType(); } else if (ObjType->isAnyComplexType()) { // Next subobject is a complex number. uint64_t Index = Sub.Entries[I].ArrayIndex; if (Index > 1) { Info.Diag(E, Info.getLangOpts().CPlusPlus0x ? (unsigned)diag::note_constexpr_read_past_end : (unsigned)diag::note_invalid_subexpr_in_const_expr); return false; } assert(I == N - 1 && "extracting subobject of scalar?"); if (O->isComplexInt()) { Obj = APValue(Index ? O->getComplexIntImag() : O->getComplexIntReal()); } else { assert(O->isComplexFloat()); Obj = APValue(Index ? O->getComplexFloatImag() : O->getComplexFloatReal()); } return true; } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { if (Field->isMutable()) { Info.Diag(E, diag::note_constexpr_ltor_mutable, 1) << Field; Info.Note(Field->getLocation(), diag::note_declared_at); return false; } // 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.Diag(E, diag::note_constexpr_read_inactive_union_member) << Field << !UnionField << UnionField; return false; } O = &O->getUnionValue(); } else O = &O->getStructField(Field->getFieldIndex()); ObjType = Field->getType(); if (ObjType.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) { // FIXME: Include a description of the path to the volatile subobject. Info.Diag(E, diag::note_constexpr_ltor_volatile_obj, 1) << 2 << Field; Info.Note(Field->getLocation(), diag::note_declared_at); } else { Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); } return false; } } 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 = Info.Ctx.getRecordType(Base); } if (O->isUninit()) { if (!Info.CheckingPotentialConstantExpression) Info.Diag(E, diag::note_constexpr_read_uninit); return false; } } // This may look super-stupid, but it serves an important purpose: if we just // swapped Obj and *O, we'd create an object which had itself as a subobject. // To avoid the leak, we ensure that Tmp ends up owning the original complete // object, which is destroyed by Tmp's destructor. APValue Tmp; O->swap(Tmp); Obj.swap(Tmp); return true; } /// 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].ArrayIndex != B.Entries[I].ArrayIndex) { WasArrayIndex = true; return I; } if (ObjType->isAnyComplexType()) ObjType = ObjType->castAs()->getElementType(); else ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); } else { if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) { 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.MostDerivedArraySize != 0; 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; } /// HandleLValueToRValueConversion - Perform an lvalue-to-rvalue conversion on /// the given lvalue. 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 we expect this conversion to produce, before /// stripping cv-qualifiers in the case of a non-clas 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) // A diagnostic will have already been produced. return false; const Expr *Base = LVal.Base.dyn_cast(); if (!LVal.Base) { // FIXME: Indirection through a null pointer deserves a specific diagnostic. Info.Diag(Conv, diag::note_invalid_subexpr_in_const_expr); return false; } CallStackFrame *Frame = 0; if (LVal.CallIndex) { Frame = Info.getCallFrame(LVal.CallIndex); if (!Frame) { Info.Diag(Conv, diag::note_constexpr_lifetime_ended, 1) << !Base; NoteLValueLocation(Info, LVal.Base); return false; } } // 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 (Type.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) Info.Diag(Conv, diag::note_constexpr_ltor_volatile_type) << Type; else Info.Diag(Conv); return false; } 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, 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.Diag(Conv); return false; } // DR1313: If the object is volatile-qualified but the glvalue was not, // behavior is undefined so the result is not a constant expression. QualType VT = VD->getType(); if (VT.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) { Info.Diag(Conv, diag::note_constexpr_ltor_volatile_obj, 1) << 1 << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.Diag(Conv); } return false; } if (!isa(VD)) { if (VD->isConstexpr()) { // OK, we can read this variable. } else if (VT->isIntegralOrEnumerationType()) { if (!VT.isConstQualified()) { if (Info.getLangOpts().CPlusPlus) { Info.Diag(Conv, diag::note_constexpr_ltor_non_const_int, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.Diag(Conv); } return false; } } else if (VT->isFloatingType() && VT.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().CPlusPlus0x) { Info.CCEDiag(Conv, diag::note_constexpr_ltor_non_constexpr, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.CCEDiag(Conv); } } else { // FIXME: Allow folding of values of any literal type in all languages. if (Info.getLangOpts().CPlusPlus0x) { Info.Diag(Conv, diag::note_constexpr_ltor_non_constexpr, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.Diag(Conv); } return false; } } if (!EvaluateVarDeclInit(Info, Conv, VD, Frame, RVal)) return false; if (isa(VD) || !VD->getAnyInitializer()->isLValue()) return ExtractSubobject(Info, Conv, RVal, VT, LVal.Designator, Type); // The declaration was initialized by an lvalue, with no lvalue-to-rvalue // conversion. This happens when the declaration and the lvalue should be // considered synonymous, for instance when initializing an array of char // from a string literal. Continue as if the initializer lvalue was the // value we were originally given. assert(RVal.getLValueOffset().isZero() && "offset for lvalue init of non-reference"); Base = RVal.getLValueBase().get(); if (unsigned CallIndex = RVal.getLValueCallIndex()) { Frame = Info.getCallFrame(CallIndex); if (!Frame) { Info.Diag(Conv, diag::note_constexpr_lifetime_ended, 1) << !Base; NoteLValueLocation(Info, RVal.getLValueBase()); return false; } } else { Frame = 0; } } // Volatile temporary objects cannot be read in constant expressions. if (Base->getType().isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) { Info.Diag(Conv, diag::note_constexpr_ltor_volatile_obj, 1) << 0; Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here); } else { Info.Diag(Conv); } return false; } if (Frame) { // If this is a temporary expression with a nontrivial initializer, grab the // value from the relevant stack frame. RVal = Frame->Temporaries[Base]; } else 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. assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); if (!Evaluate(RVal, Info, CLE->getInitializer())) return false; } else if (isa(Base)) { // We represent a string literal array as an lvalue pointing at the // corresponding expression, rather than building an array of chars. // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant RVal = APValue(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0); } else { Info.Diag(Conv, diag::note_invalid_subexpr_in_const_expr); return false; } return ExtractSubobject(Info, Conv, RVal, Base->getType(), LVal.Designator, Type); } /// 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()) return EvaluateTemporary(Object, This, Info); return false; } /// HandleMemberPointerAccess - Evaluate a member access operation and build an /// lvalue referring to the result. /// /// \param Info - Information about the ongoing evaluation. /// \param BO - The member pointer access operation. /// \param LV - Filled in with a reference to the resulting object. /// \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, const BinaryOperator *BO, LValue &LV, bool IncludeMember = true) { assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); bool EvalObjOK = EvaluateObjectArgument(Info, BO->getLHS(), LV); if (!EvalObjOK && !Info.keepEvaluatingAfterFailure()) return 0; MemberPtr MemPtr; if (!EvaluateMemberPointer(BO->getRHS(), MemPtr, Info)) return 0; // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to // member value, the behavior is undefined. if (!MemPtr.getDecl()) return 0; if (!EvalObjOK) return 0; 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()) return 0; 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()) return 0; } // Truncate the lvalue to the appropriate derived class. if (!CastToDerivedClass(Info, BO, LV, MemPtr.getContainingRecord(), PathLengthToMember)) return 0; } 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. QualType LVType = BO->getLHS()->getType(); 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]; HandleLValueDirectBase(Info, BO, LV, RD, Base); RD = Base; } // Finally cast to the class containing the member. HandleLValueDirectBase(Info, BO, LV, RD, MemPtr.getContainingRecord()); } // Add the member. Note that we cannot build bound member functions here. if (IncludeMember) { if (const FieldDecl *FD = dyn_cast(MemPtr.getDecl())) HandleLValueMember(Info, BO, LV, FD); else if (const IndirectFieldDecl *IFD = dyn_cast(MemPtr.getDecl())) HandleLValueIndirectMember(Info, BO, LV, IFD); else llvm_unreachable("can't construct reference to bound member function"); } return MemPtr.getDecl(); } /// 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 }; } // Evaluate a statement. static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, const Stmt *S) { switch (S->getStmtClass()) { default: return ESR_Failed; case Stmt::NullStmtClass: case Stmt::DeclStmtClass: return ESR_Succeeded; case Stmt::ReturnStmtClass: { const Expr *RetExpr = cast(S)->getRetValue(); if (!Evaluate(Result, Info, RetExpr)) return ESR_Failed; return ESR_Returned; } case Stmt::CompoundStmtClass: { const CompoundStmt *CS = cast(S); for (CompoundStmt::const_body_iterator BI = CS->body_begin(), BE = CS->body_end(); BI != BE; ++BI) { EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI); if (ESR != ESR_Succeeded) return ESR; } return ESR_Succeeded; } } } /// 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().CPlusPlus0x) { // 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) { // Potential constant expressions can contain calls to declared, but not yet // defined, constexpr functions. if (Info.CheckingPotentialConstantExpression && !Definition && Declaration->isConstexpr()) return false; // Can we evaluate this function call? if (Definition && Definition->isConstexpr() && !Definition->isInvalidDecl()) return true; if (Info.getLangOpts().CPlusPlus0x) { const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; // FIXME: If DiagDecl is an implicitly-declared special member function, we // should be much more explicit about why it's not constexpr. Info.Diag(CallLoc, diag::note_constexpr_invalid_function, 1) << DiagDecl->isConstexpr() << isa(DiagDecl) << DiagDecl; Info.Note(DiagDecl->getLocation(), diag::note_declared_at); } else { Info.Diag(CallLoc, diag::note_invalid_subexpr_in_const_expr); } return false; } namespace { typedef SmallVector ArgVector; } /// EvaluateArgs - Evaluate the arguments to a function call. static bool EvaluateArgs(ArrayRef Args, ArgVector &ArgValues, EvalInfo &Info) { bool Success = true; 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.keepEvaluatingAfterFailure()) 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) { ArgVector ArgValues(Args.size()); if (!EvaluateArgs(Args, ArgValues, Info)) return false; if (!Info.CheckCallLimit(CallLoc)) return false; CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); return EvaluateStmt(Result, Info, Body) == ESR_Returned; } /// Evaluate a constructor call. static bool HandleConstructorCall(SourceLocation CallLoc, const LValue &This, ArrayRef Args, const CXXConstructorDecl *Definition, EvalInfo &Info, APValue &Result) { ArgVector ArgValues(Args.size()); if (!EvaluateArgs(Args, ArgValues, Info)) return false; if (!Info.CheckCallLimit(CallLoc)) return false; const CXXRecordDecl *RD = Definition->getParent(); if (RD->getNumVBases()) { Info.Diag(CallLoc, diag::note_constexpr_virtual_base) << RD; return false; } CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues.data()); // If it's a delegating constructor, just delegate. if (Definition->isDelegatingConstructor()) { CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); return EvaluateInPlace(Result, Info, This, (*I)->getInit()); } // For a trivial copy or move constructor, perform an APValue copy. This is // essential for unions, where the operations performed by the constructor // cannot be represented by ctor-initializers. if (Definition->isDefaulted() && ((Definition->isCopyConstructor() && Definition->isTrivial()) || (Definition->isMoveConstructor() && Definition->isTrivial()))) { LValue RHS; RHS.setFrom(Info.Ctx, ArgValues[0]); return HandleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), RHS, Result); } // Reserve space for the struct members. if (!RD->isUnion() && Result.isUninit()) Result = APValue(APValue::UninitStruct(), RD->getNumBases(), std::distance(RD->field_begin(), RD->field_end())); const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); bool Success = true; unsigned BasesSeen = 0; #ifndef NDEBUG CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); #endif for (CXXConstructorDecl::init_const_iterator I = Definition->init_begin(), E = Definition->init_end(); I != E; ++I) { LValue Subobject = This; APValue *Value = &Result; // Determine the subobject to initialize. 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 HandleLValueDirectBase(Info, (*I)->getInit(), Subobject, RD, BaseType->getAsCXXRecordDecl(), &Layout); Value = &Result.getStructBase(BasesSeen++); } else if (FieldDecl *FD = (*I)->getMember()) { HandleLValueMember(Info, (*I)->getInit(), Subobject, FD, &Layout); 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. for (IndirectFieldDecl::chain_iterator C = IFD->chain_begin(), CE = IFD->chain_end(); C != CE; ++C) { FieldDecl *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->isUninit() || (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())); } HandleLValueMember(Info, (*I)->getInit(), Subobject, FD); if (CD->isUnion()) Value = &Value->getUnionValue(); else Value = &Value->getStructField(FD->getFieldIndex()); } } else { llvm_unreachable("unknown base initializer kind"); } if (!EvaluateInPlace(*Value, Info, Subobject, (*I)->getInit(), (*I)->isBaseInitializer() ? CCEK_Constant : CCEK_MemberInit)) { // If we're checking for a potential constant expression, evaluate all // initializers even if some of them fail. if (!Info.keepEvaluatingAfterFailure()) return false; Success = false; } } return Success; } namespace { class HasSideEffect : public ConstStmtVisitor { const ASTContext &Ctx; public: HasSideEffect(const ASTContext &C) : Ctx(C) {} // Unhandled nodes conservatively default to having side effects. bool VisitStmt(const Stmt *S) { return true; } bool VisitParenExpr(const ParenExpr *E) { return Visit(E->getSubExpr()); } bool VisitGenericSelectionExpr(const GenericSelectionExpr *E) { return Visit(E->getResultExpr()); } bool VisitDeclRefExpr(const DeclRefExpr *E) { if (Ctx.getCanonicalType(E->getType()).isVolatileQualified()) return true; return false; } bool VisitObjCIvarRefExpr(const ObjCIvarRefExpr *E) { if (Ctx.getCanonicalType(E->getType()).isVolatileQualified()) return true; return false; } // We don't want to evaluate BlockExprs multiple times, as they generate // a ton of code. bool VisitBlockExpr(const BlockExpr *E) { return true; } bool VisitPredefinedExpr(const PredefinedExpr *E) { return false; } bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { return Visit(E->getInitializer()); } bool VisitMemberExpr(const MemberExpr *E) { return Visit(E->getBase()); } bool VisitIntegerLiteral(const IntegerLiteral *E) { return false; } bool VisitFloatingLiteral(const FloatingLiteral *E) { return false; } bool VisitStringLiteral(const StringLiteral *E) { return false; } bool VisitCharacterLiteral(const CharacterLiteral *E) { return false; } bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E) { return false; } bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { return Visit(E->getLHS()) || Visit(E->getRHS()); } bool VisitChooseExpr(const ChooseExpr *E) { return Visit(E->getChosenSubExpr(Ctx)); } bool VisitCastExpr(const CastExpr *E) { return Visit(E->getSubExpr()); } bool VisitBinAssign(const BinaryOperator *E) { return true; } bool VisitCompoundAssignOperator(const BinaryOperator *E) { return true; } bool VisitBinaryOperator(const BinaryOperator *E) { return Visit(E->getLHS()) || Visit(E->getRHS()); } bool VisitUnaryPreInc(const UnaryOperator *E) { return true; } bool VisitUnaryPostInc(const UnaryOperator *E) { return true; } bool VisitUnaryPreDec(const UnaryOperator *E) { return true; } bool VisitUnaryPostDec(const UnaryOperator *E) { return true; } bool VisitUnaryDeref(const UnaryOperator *E) { if (Ctx.getCanonicalType(E->getType()).isVolatileQualified()) return true; return Visit(E->getSubExpr()); } bool VisitUnaryOperator(const UnaryOperator *E) { return Visit(E->getSubExpr()); } // Has side effects if any element does. bool VisitInitListExpr(const InitListExpr *E) { for (unsigned i = 0, e = E->getNumInits(); i != e; ++i) if (Visit(E->getInit(i))) return true; if (const Expr *filler = E->getArrayFiller()) return Visit(filler); return false; } bool VisitSizeOfPackExpr(const SizeOfPackExpr *) { return false; } }; class OpaqueValueEvaluation { EvalInfo &info; OpaqueValueExpr *opaqueValue; public: OpaqueValueEvaluation(EvalInfo &info, OpaqueValueExpr *opaqueValue, Expr *value) : info(info), opaqueValue(opaqueValue) { // If evaluation fails, fail immediately. if (!Evaluate(info.OpaqueValues[opaqueValue], info, value)) { this->opaqueValue = 0; return; } } bool hasError() const { return opaqueValue == 0; } ~OpaqueValueEvaluation() { // FIXME: For a recursive constexpr call, an outer stack frame might have // been using this opaque value too, and will now have to re-evaluate the // source expression. if (opaqueValue) info.OpaqueValues.erase(opaqueValue); } }; } // end anonymous namespace //===----------------------------------------------------------------------===// // Generic Evaluation //===----------------------------------------------------------------------===// namespace { // FIXME: RetTy is always bool. Remove it. template class ExprEvaluatorBase : public ConstStmtVisitor { private: RetTy DerivedSuccess(const APValue &V, const Expr *E) { return static_cast(this)->Success(V, E); } RetTy DerivedZeroInitialization(const Expr *E) { return static_cast(this)->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. { llvm::SmallVector Diag; SpeculativeEvaluationRAII Speculate(Info, &Diag); StmtVisitorTy::Visit(E->getFalseExpr()); if (Diag.empty()) return; 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) CheckPotentialConstantConditional(E); 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); } RetTy 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.Diag(E, D); return false; } bool Error(const Expr *E) { return Error(E, diag::note_invalid_subexpr_in_const_expr); } RetTy VisitStmt(const Stmt *) { llvm_unreachable("Expression evaluator should not be called on stmts"); } RetTy VisitExpr(const Expr *E) { return Error(E); } RetTy VisitParenExpr(const ParenExpr *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } RetTy VisitUnaryExtension(const UnaryOperator *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } RetTy VisitUnaryPlus(const UnaryOperator *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } RetTy VisitChooseExpr(const ChooseExpr *E) { return StmtVisitorTy::Visit(E->getChosenSubExpr(Info.Ctx)); } RetTy VisitGenericSelectionExpr(const GenericSelectionExpr *E) { return StmtVisitorTy::Visit(E->getResultExpr()); } RetTy VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) { return StmtVisitorTy::Visit(E->getReplacement()); } RetTy VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) { 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. RetTy VisitExprWithCleanups(const ExprWithCleanups *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } RetTy VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; return static_cast(this)->VisitCastExpr(E); } RetTy VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; return static_cast(this)->VisitCastExpr(E); } RetTy 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); } } } RetTy VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { // Cache the value of the common expression. OpaqueValueEvaluation opaque(Info, E->getOpaqueValue(), E->getCommon()); if (opaque.hasError()) return false; return HandleConditionalOperator(E); } RetTy 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->isBuiltinCall() == 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. if (Info.CheckingPotentialConstantExpression && IsBcpCall) return false; FoldConstant Fold(Info); if (!HandleConditionalOperator(E)) return false; if (IsBcpCall) Fold.Fold(Info); return true; } RetTy VisitOpaqueValueExpr(const OpaqueValueExpr *E) { const APValue *Value = Info.getOpaqueValue(E); if (!Value) { 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); } return DerivedSuccess(*Value, E); } RetTy VisitCallExpr(const CallExpr *E) { const Expr *Callee = E->getCallee()->IgnoreParens(); QualType CalleeType = Callee->getType(); const FunctionDecl *FD = 0; LValue *This = 0, ThisVal; llvm::ArrayRef Args(E->getArgs(), E->getNumArgs()); bool HasQualifier = false; // Extract function decl and 'this' pointer from the callee. if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { const ValueDecl *Member = 0; 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 = ME->getMemberDecl(); This = &ThisVal; HasQualifier = ME->hasQualifier(); } else if (const BinaryOperator *BE = dyn_cast(Callee)) { // Indirect bound member calls ('.*' or '->*'). Member = HandleMemberPointerAccess(Info, BE, ThisVal, false); if (!Member) return false; This = &ThisVal; } else return Error(Callee); FD = dyn_cast(Member); if (!FD) return Error(Callee); } 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); // 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); } // Don't call function pointers which have been cast to some other type. if (!Info.Ctx.hasSameType(CalleeType->getPointeeType(), FD->getType())) return Error(E); } else return Error(E); if (This && !This->checkSubobject(Info, E, CSK_This)) return false; // DR1358 allows virtual constexpr functions in some cases. Don't allow // calls to such functions in constant expressions. if (This && !HasQualifier && isa(FD) && cast(FD)->isVirtual()) return Error(E, diag::note_constexpr_virtual_call); const FunctionDecl *Definition = 0; Stmt *Body = FD->getBody(Definition); APValue Result; if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition) || !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info, Result)) return false; return DerivedSuccess(Result, E); } RetTy VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { return StmtVisitorTy::Visit(E->getInitializer()); } RetTy VisitInitListExpr(const InitListExpr *E) { if (E->getNumInits() == 0) return DerivedZeroInitialization(E); if (E->getNumInits() == 1) return StmtVisitorTy::Visit(E->getInit(0)); return Error(E); } RetTy VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { return DerivedZeroInitialization(E); } RetTy VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { return DerivedZeroInitialization(E); } RetTy VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { return DerivedZeroInitialization(E); } /// A member expression where the object is a prvalue is itself a prvalue. RetTy VisitMemberExpr(const MemberExpr *E) { 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->getAs()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"); SubobjectDesignator Designator(BaseTy); Designator.addDeclUnchecked(FD); return ExtractSubobject(Info, E, Val, BaseTy, Designator, E->getType()) && DerivedSuccess(Val, E); } RetTy VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: break; case CK_AtomicToNonAtomic: case CK_NonAtomicToAtomic: 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); } } return Error(E); } /// Visit a value which is evaluated, but whose value is ignored. void VisitIgnoredValue(const Expr *E) { APValue Scratch; if (!Evaluate(Scratch, Info, E)) Info.EvalStatus.HasSideEffects = true; } }; } //===----------------------------------------------------------------------===// // Common base class for lvalue and temporary evaluation. //===----------------------------------------------------------------------===// namespace { template class LValueExprEvaluatorBase : public ExprEvaluatorBase { protected: LValue &Result; typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; typedef ExprEvaluatorBase ExprEvaluatorBaseTy; bool Success(APValue::LValueBase B) { Result.set(B); return true; } public: LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result) : ExprEvaluatorBaseTy(Info), Result(Result) {} 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; if (E->isArrow()) { if (!EvaluatePointer(E->getBase(), Result, this->Info)) return false; BaseTy = E->getBase()->getType()->getAs()->getPointeeType(); } else if (E->getBase()->isRValue()) { assert(E->getBase()->getType()->isRecordType()); if (!EvaluateTemporary(E->getBase(), Result, this->Info)) return false; BaseTy = E->getBase()->getType(); } else { if (!this->Visit(E->getBase())) return false; BaseTy = E->getBase()->getType(); } 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; HandleLValueMember(this->Info, E, Result, FD); } else if (const IndirectFieldDecl *IFD = dyn_cast(MD)) { HandleLValueIndirectMember(this->Info, E, Result, IFD); } 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. QualType Type = E->getSubExpr()->getType(); for (CastExpr::path_const_iterator PathI = E->path_begin(), PathE = E->path_end(); PathI != PathE; ++PathI) { if (!HandleLValueBase(this->Info, E, Result, Type->getAsCXXRecordDecl(), *PathI)) return false; Type = (*PathI)->getType(); } return true; } } } }; } //===----------------------------------------------------------------------===// // 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 // * StringLiteral // * CXXTypeidExpr // * PredefinedExpr // * ObjCStringLiteralExpr // * ObjCEncodeExpr // * AddrLabelExpr // * BlockExpr // * CallExpr for a MakeStringConstant builtin // - Locals and temporaries // * Any Expr, with a CallIndex indicating the function in which the temporary // was evaluated. // plus an offset in bytes. //===----------------------------------------------------------------------===// namespace { class LValueExprEvaluator : public LValueExprEvaluatorBase { public: LValueExprEvaluator(EvalInfo &Info, LValue &Result) : LValueExprEvaluatorBaseTy(Info, Result) {} bool VisitVarDecl(const Expr *E, const VarDecl *VD); 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 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); } } }; } // end anonymous namespace /// Evaluate an expression as an lvalue. This can be legitimately called on /// expressions which are not glvalues, in a few cases: /// * function designators in C, /// * "extern void" objects, /// * temporaries, if building with -Wno-address-of-temporary. static bool EvaluateLValue(const Expr* E, LValue& Result, EvalInfo &Info) { assert((E->isGLValue() || E->getType()->isFunctionType() || E->getType()->isVoidType() || isa(E)) && "can't evaluate expression as an lvalue"); return LValueExprEvaluator(Info, Result).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); return Error(E); } bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { if (!VD->getType()->isReferenceType()) { if (isa(VD)) { Result.set(VD, Info.CurrentCall->Index); return true; } return Success(VD); } APValue V; if (!EvaluateVarDeclInit(Info, E, VD, Info.CurrentCall, V)) return false; return Success(V, E); } bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( const MaterializeTemporaryExpr *E) { if (E->GetTemporaryExpr()->isRValue()) { if (E->getType()->isRecordType()) return EvaluateTemporary(E->GetTemporaryExpr(), Result, Info); Result.set(E, Info.CurrentCall->Index); return EvaluateInPlace(Info.CurrentCall->Temporaries[E], Info, Result, E->GetTemporaryExpr()); } // Materialization of an lvalue temporary occurs when we need to force a copy // (for instance, if it's a bitfield). // FIXME: The AST should contain an lvalue-to-rvalue node for such cases. if (!Visit(E->GetTemporaryExpr())) return false; if (!HandleLValueToRValueConversion(Info, E, E->getType(), Result, Info.CurrentCall->Temporaries[E])) return false; Result.set(E, Info.CurrentCall->Index); return true; } bool LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { assert(!Info.getLangOpts().CPlusPlus && "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) { if (E->isTypeOperand()) return Success(E); CXXRecordDecl *RD = E->getExprOperand()->getType()->getAsCXXRecordDecl(); if (RD && RD->isPolymorphic()) { Info.Diag(E, diag::note_constexpr_typeid_polymorphic) << E->getExprOperand()->getType() << E->getExprOperand()->getSourceRange(); return false; } return Success(E); } 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())) { VisitIgnoredValue(E->getBase()); return VisitVarDecl(E, VD); } // Handle static member functions. if (const CXXMethodDecl *MD = dyn_cast(E->getMemberDecl())) { if (MD->isStatic()) { VisitIgnoredValue(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); if (!EvaluatePointer(E->getBase(), Result, Info)) return false; APSInt Index; if (!EvaluateInteger(E->getIdx(), Index, Info)) return false; int64_t IndexValue = Index.isSigned() ? Index.getSExtValue() : static_cast(Index.getZExtValue()); return HandleLValueArrayAdjustment(Info, E, Result, E->getType(), IndexValue); } bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { return EvaluatePointer(E->getSubExpr(), Result, Info); } 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; } //===----------------------------------------------------------------------===// // Pointer Evaluation //===----------------------------------------------------------------------===// namespace { class PointerExprEvaluator : public ExprEvaluatorBase { LValue &Result; bool Success(const Expr *E) { Result.set(E); return true; } public: PointerExprEvaluator(EvalInfo &info, LValue &Result) : ExprEvaluatorBaseTy(info), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result.setFrom(Info.Ctx, V); return true; } bool ZeroInitialization(const Expr *E) { return Success((Expr*)0); } bool VisitBinaryOperator(const BinaryOperator *E); bool VisitCastExpr(const CastExpr* E); bool VisitUnaryAddrOf(const UnaryOperator *E); bool VisitObjCStringLiteral(const ObjCStringLiteral *E) { return Success(E); } bool VisitObjCNumericLiteral(const ObjCNumericLiteral *E) { return Success(E); } bool VisitAddrLabelExpr(const AddrLabelExpr *E) { return Success(E); } bool VisitCallExpr(const CallExpr *E); bool VisitBlockExpr(const BlockExpr *E) { if (!E->getBlockDecl()->hasCaptures()) return Success(E); return Error(E); } bool VisitCXXThisExpr(const CXXThisExpr *E) { if (!Info.CurrentCall->This) return Error(E); Result = *Info.CurrentCall->This; return true; } // FIXME: Missing: @protocol, @selector }; } // end anonymous namespace static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->hasPointerRepresentation()); return PointerExprEvaluator(Info, Result).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, Info); if (!EvalPtrOK && !Info.keepEvaluatingAfterFailure()) return false; llvm::APSInt Offset; if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) return false; int64_t AdditionalOffset = Offset.isSigned() ? Offset.getSExtValue() : static_cast(Offset.getZExtValue()); if (E->getOpcode() == BO_Sub) AdditionalOffset = -AdditionalOffset; QualType Pointee = PExp->getType()->getAs()->getPointeeType(); return HandleLValueArrayAdjustment(Info, E, Result, Pointee, AdditionalOffset); } bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { return EvaluateLValue(E->getSubExpr(), Result, Info); } 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: 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; } return true; case CK_DerivedToBase: case CK_UncheckedDerivedToBase: { if (!EvaluatePointer(E->getSubExpr(), Result, Info)) 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. QualType Type = E->getSubExpr()->getType()->castAs()->getPointeeType(); 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; } case CK_BaseToDerived: if (!Visit(E->getSubExpr())) return false; if (!Result.Base && Result.Offset.isZero()) return true; return HandleBaseToDerivedCast(Info, 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*)0; Result.Offset = CharUnits::fromQuantity(N); Result.CallIndex = 0; Result.Designator.setInvalid(); 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, Info)) return false; } else { Result.set(SubExpr, Info.CurrentCall->Index); if (!EvaluateInPlace(Info.CurrentCall->Temporaries[SubExpr], Info, Result, SubExpr)) return false; } // The result is a pointer to the first element of the array. if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(SubExpr->getType())) Result.addArray(Info, E, CAT); else Result.Designator.setInvalid(); return true; case CK_FunctionToPointerDecay: return EvaluateLValue(SubExpr, Result, Info); } return ExprEvaluatorBaseTy::VisitCastExpr(E); } bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { if (IsStringLiteralCall(E)) return Success(E); return ExprEvaluatorBaseTy::VisitCallExpr(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*)0); } 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); bool VisitCastExpr(const CastExpr *E); bool VisitInitListExpr(const InitListExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *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())); 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; HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout); if (!HandleClassZeroInitialization(Info, E, Base, Subobject, Result.getStructBase(Index))) return false; } } for (RecordDecl::field_iterator I = RD->field_begin(), End = RD->field_end(); I != End; ++I) { // -- if T is a reference type, no initialization is performed. if ((*I)->getType()->isReferenceType()) continue; LValue Subobject = This; HandleLValueMember(Info, E, Subobject, *I, &Layout); ImplicitValueInitExpr VIE((*I)->getType()); if (!EvaluateInPlace( Result.getStructField((*I)->getFieldIndex()), Info, Subobject, &VIE)) return false; } return true; } bool RecordExprEvaluator::ZeroInitialization(const Expr *E) { const RecordDecl *RD = E->getType()->castAs()->getDecl(); 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*)0); return true; } LValue Subobject = This; HandleLValueMember(Info, E, Subobject, *I); Result = APValue(*I); ImplicitValueInitExpr VIE((*I)->getType()); return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); } if (isa(RD) && cast(RD)->getNumVBases()) { Info.Diag(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) { // Cannot constant-evaluate std::initializer_list inits. if (E->initializesStdInitializerList()) return false; const RecordDecl *RD = E->getType()->castAs()->getDecl(); const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 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. ImplicitValueInitExpr VIE(Field->getType()); const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; LValue Subobject = This; HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout); return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); } assert((!isa(RD) || !cast(RD)->getNumBases()) && "initializer list for class with base classes"); Result = APValue(APValue::UninitStruct(), 0, std::distance(RD->field_begin(), RD->field_end())); unsigned ElementNo = 0; bool Success = true; for (RecordDecl::field_iterator Field = RD->field_begin(), FieldEnd = RD->field_end(); Field != FieldEnd; ++Field) { // 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. HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, Subobject, *Field, &Layout); // Perform an implicit value-initialization for members beyond the end of // the initializer list. ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); if (!EvaluateInPlace( Result.getStructField((*Field)->getFieldIndex()), Info, Subobject, HaveInit ? E->getInit(ElementNo++) : &VIE)) { if (!Info.keepEvaluatingAfterFailure()) return false; Success = false; } } return Success; } bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { const CXXConstructorDecl *FD = E->getConstructor(); bool ZeroInit = E->requiresZeroInitialization(); if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { // If we've already performed zero-initialization, we're already done. if (!Result.isUninit()) return true; if (ZeroInit) return ZeroInitialization(E); const CXXRecordDecl *RD = FD->getParent(); if (RD->isUnion()) Result = APValue((FieldDecl*)0); else Result = APValue(APValue::UninitStruct(), RD->getNumBases(), std::distance(RD->field_begin(), RD->field_end())); return true; } const FunctionDecl *Definition = 0; FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) 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)) return false; llvm::ArrayRef Args(E->getArgs(), E->getNumArgs()); return HandleConstructorCall(E->getExprLoc(), This, Args, cast(Definition), Info, Result); } 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) {} /// Visit an expression which constructs the value of this temporary. bool VisitConstructExpr(const Expr *E) { Result.set(E, Info.CurrentCall->Index); return EvaluateInPlace(Info.CurrentCall->Temporaries[E], 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); } }; } // 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(const 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(IntResult); } else if (SETy->isRealFloatingType()) { APFloat F(0.0); if (!EvaluateFloat(SE, F, Info)) return false; Val = APValue(F); } 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); bool isIEESem = &Sem != &APFloat::PPCDoubleDouble; 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(Elt, isIEESem))); } } 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()->isExtVectorType()) { 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() || V.isLValue()) && "expected array or string literal"); 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 VisitInitListExpr(const InitListExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E); }; } // 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); } 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()) { LValue LV; if (!EvaluateLValue(E->getInit(0), LV, Info)) return false; APValue Val; LV.moveInto(Val); return Success(Val, E); } bool Success = true; Result = APValue(APValue::UninitArray(), E->getNumInits(), CAT->getSize().getZExtValue()); LValue Subobject = This; Subobject.addArray(Info, E, CAT); unsigned Index = 0; for (InitListExpr::const_iterator I = E->begin(), End = E->end(); I != End; ++I, ++Index) { if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), Info, Subobject, cast(*I)) || !HandleLValueArrayAdjustment(Info, cast(*I), Subobject, CAT->getElementType(), 1)) { if (!Info.keepEvaluatingAfterFailure()) return false; Success = false; } } if (!Result.hasArrayFiller()) return Success; assert(E->hasArrayFiller() && "no array filler for incomplete init list"); // FIXME: The Subobject here isn't necessarily right. This rarely matters, // but sometimes does: // struct S { constexpr S() : p(&p) {} void *p; }; // S s[10] = {}; return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, E->getArrayFiller()) && Success; } bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); if (!CAT) return Error(E); bool HadZeroInit = !Result.isUninit(); if (!HadZeroInit) Result = APValue(APValue::UninitArray(), 0, CAT->getSize().getZExtValue()); if (!Result.hasArrayFiller()) return true; const CXXConstructorDecl *FD = E->getConstructor(); bool ZeroInit = E->requiresZeroInitialization(); if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { if (HadZeroInit) return true; if (ZeroInit) { LValue Subobject = This; Subobject.addArray(Info, E, CAT); ImplicitValueInitExpr VIE(CAT->getElementType()); return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); } const CXXRecordDecl *RD = FD->getParent(); if (RD->isUnion()) Result.getArrayFiller() = APValue((FieldDecl*)0); else Result.getArrayFiller() = APValue(APValue::UninitStruct(), RD->getNumBases(), std::distance(RD->field_begin(), RD->field_end())); return true; } const FunctionDecl *Definition = 0; FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) return false; // FIXME: The Subobject here isn't necessarily right. This rarely matters, // but sometimes does: // struct S { constexpr S() : p(&p) {} void *p; }; // S s[10]; LValue Subobject = This; Subobject.addArray(Info, E, CAT); if (ZeroInit && !HadZeroInit) { ImplicitValueInitExpr VIE(CAT->getElementType()); if (!EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE)) return false; } llvm::ArrayRef Args(E->getArgs(), E->getNumArgs()); return HandleConstructorCall(E->getExprLoc(), Subobject, Args, cast(Definition), Info, Result.getArrayFiller()); } //===----------------------------------------------------------------------===// // 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()) { Result = V; return true; } return Success(V.getInt(), E); } bool ZeroInitialization(const Expr *E) { return Success(0, E); } //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// 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())) { VisitIgnoredValue(E->getBase()); return true; } return ExprEvaluatorBaseTy::VisitMemberExpr(E); } bool VisitCallExpr(const CallExpr *E); 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); } // Note, GNU defines __null as an integer, not a pointer. bool VisitGNUNullExpr(const GNUNullExpr *E) { return ZeroInitialization(E); } bool VisitUnaryTypeTraitExpr(const UnaryTypeTraitExpr *E) { return Success(E->getValue(), E); } bool VisitBinaryTypeTraitExpr(const BinaryTypeTraitExpr *E) { return Success(E->getValue(), 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); private: CharUnits GetAlignOfExpr(const Expr *E); CharUnits GetAlignOfType(QualType T); static QualType GetObjectType(APValue::LValueBase B); bool TryEvaluateBuiltinObjectSize(const CallExpr *E); // FIXME: Missing: array subscript of vector, member of vector }; } // 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.Diag(E, diag::note_invalid_subexpr_in_const_expr); return false; } Result = Val.getInt(); return true; } /// 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; } /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way /// as GCC. static int EvaluateBuiltinClassifyType(const CallExpr *E) { // The following enum mimics the values returned by GCC. // FIXME: Does GCC differ between lvalue and rvalue references here? enum gcc_type_class { no_type_class = -1, void_type_class, integer_type_class, char_type_class, enumeral_type_class, boolean_type_class, pointer_type_class, reference_type_class, offset_type_class, real_type_class, complex_type_class, function_type_class, method_type_class, record_type_class, union_type_class, array_type_class, string_type_class, lang_type_class }; // If no argument was supplied, default to "no_type_class". This isn't // ideal, however it is what gcc does. if (E->getNumArgs() == 0) return no_type_class; QualType ArgTy = E->getArg(0)->getType(); if (ArgTy->isVoidType()) return void_type_class; else if (ArgTy->isEnumeralType()) return enumeral_type_class; else if (ArgTy->isBooleanType()) return boolean_type_class; else if (ArgTy->isCharType()) return string_type_class; // gcc doesn't appear to use char_type_class else if (ArgTy->isIntegerType()) return integer_type_class; else if (ArgTy->isPointerType()) return pointer_type_class; else if (ArgTy->isReferenceType()) return reference_type_class; else if (ArgTy->isRealType()) return real_type_class; else if (ArgTy->isComplexType()) return complex_type_class; else if (ArgTy->isFunctionType()) return function_type_class; else if (ArgTy->isStructureOrClassType()) return record_type_class; else if (ArgTy->isUnionType()) return union_type_class; else if (ArgTy->isArrayType()) return array_type_class; else if (ArgTy->isUnionType()) return union_type_class; else // FIXME: offset_type_class, method_type_class, & lang_type_class? llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); } /// EvaluateBuiltinConstantPForLValue - Determine the result of /// __builtin_constant_p when applied to the given lvalue. /// /// An lvalue is only "constant" if it is a pointer or reference to the first /// character of a string literal. template static bool EvaluateBuiltinConstantPForLValue(const LValue &LV) { const Expr *E = LV.getLValueBase().template dyn_cast(); return E && isa(E) && LV.getLValueOffset().isZero(); } /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to /// GCC as we can manage. static bool EvaluateBuiltinConstantP(ASTContext &Ctx, const Expr *Arg) { 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 and can be folded to a pointer to the first character // of a string literal (or such a pointer cast to an integral type), it // returns 1. // // Otherwise, it returns 0. // // FIXME: GCC also intends to return 1 for literals of aggregate types, but // its support for this does not currently work. if (ArgType->isIntegralOrEnumerationType()) { Expr::EvalResult Result; if (!Arg->EvaluateAsRValue(Result, Ctx) || Result.HasSideEffects) return false; APValue &V = Result.Val; if (V.getKind() == APValue::Int) return true; return EvaluateBuiltinConstantPForLValue(V); } else if (ArgType->isFloatingType() || ArgType->isAnyComplexType()) { return Arg->isEvaluatable(Ctx); } else if (ArgType->isPointerType() || Arg->isGLValue()) { LValue LV; Expr::EvalStatus Status; EvalInfo Info(Ctx, Status); if ((Arg->isGLValue() ? EvaluateLValue(Arg, LV, Info) : EvaluatePointer(Arg, LV, Info)) && !Status.HasSideEffects) return EvaluateBuiltinConstantPForLValue(LV); } // 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. QualType IntExprEvaluator::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(); } return QualType(); } bool IntExprEvaluator::TryEvaluateBuiltinObjectSize(const CallExpr *E) { // TODO: Perhaps we should let LLVM lower this? LValue Base; if (!EvaluatePointer(E->getArg(0), Base, Info)) return false; // If we can prove the base is null, lower to zero now. if (!Base.getLValueBase()) return Success(0, E); QualType T = GetObjectType(Base.getLValueBase()); if (T.isNull() || T->isIncompleteType() || T->isFunctionType() || T->isVariablyModifiedType() || T->isDependentType()) return Error(E); CharUnits Size = Info.Ctx.getTypeSizeInChars(T); CharUnits Offset = Base.getLValueOffset(); if (!Offset.isNegative() && Offset <= Size) Size -= Offset; else Size = CharUnits::Zero(); return Success(Size, E); } bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { switch (unsigned BuiltinOp = E->isBuiltinCall()) { default: return ExprEvaluatorBaseTy::VisitCallExpr(E); case Builtin::BI__builtin_object_size: { if (TryEvaluateBuiltinObjectSize(E)) return true; // If evaluating the argument has side-effects we can't determine // the size of the object and lower it to unknown now. if (E->getArg(0)->HasSideEffects(Info.Ctx)) { if (E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue() <= 1) return Success(-1ULL, E); return Success(0, E); } return Error(E); } case Builtin::BI__builtin_classify_type: return Success(EvaluateBuiltinClassifyType(E), E); case Builtin::BI__builtin_constant_p: return Success(EvaluateBuiltinConstantP(Info.Ctx, E->getArg(0)), 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::BIstrlen: // A call to strlen is not a constant expression. if (Info.getLangOpts().CPlusPlus0x) Info.CCEDiag(E, diag::note_constexpr_invalid_function) << /*isConstexpr*/0 << /*isConstructor*/0 << "'strlen'"; else Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); // Fall through. case Builtin::BI__builtin_strlen: // As an extension, we support strlen() and __builtin_strlen() as constant // expressions when the argument is a string literal. if (const StringLiteral *S = dyn_cast(E->getArg(0)->IgnoreParenImpCasts())) { // The string literal may have embedded null characters. Find the first // one and truncate there. StringRef Str = S->getString(); StringRef::size_type Pos = Str.find(0); if (Pos != StringRef::npos) Str = Str.substr(0, Pos); return Success(Str.size(), E); } return Error(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); } } } return BuiltinOp == Builtin::BI__atomic_always_lock_free ? Success(0, E) : Error(E); } } } 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(); } /// 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 APSInt CheckedIntArithmetic(EvalInfo &Info, const Expr *E, const APSInt &LHS, const APSInt &RHS, unsigned BitWidth, Operation Op) { if (LHS.isUnsigned()) return Op(LHS, RHS); APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); APSInt Result = Value.trunc(LHS.getBitWidth()); if (Result.extend(BitWidth) != Value) HandleOverflow(Info, E, Value, E->getType()); return Result; } namespace { /// \brief 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() : StoredInfo(0) { } void startSpeculativeEval(EvalInfo &Info) { OldEvalStatus = Info.EvalStatus; Info.EvalStatus.Diag = 0; StoredInfo = &Info; } ~Job() { if (StoredInfo) { StoredInfo->EvalStatus = OldEvalStatus; } } private: EvalInfo *StoredInfo; // non-null if status changed. Expr::EvalStatus OldEvalStatus; }; SmallVector Queue; IntExprEvaluator &IntEval; EvalInfo &Info; APValue &FinalResult; public: DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } /// \brief 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->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); } // \brief 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) Info.EvalStatus.HasSideEffects = true; return true; } if (E->isLogicalOp()) { bool lhsResult; if (HandleConversionToBool(LHSResult.Val, lhsResult)) { // 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 (lhsResult == (E->getOpcode() == BO_LOr)) { Success(lhsResult, E, LHSResult.Val); return false; // Ignore RHS } } else { // Since we weren't able to evaluate the left hand side, it // must have had side effects. Info.EvalStatus.HasSideEffects = true; // 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.keepEvaluatingAfterFailure()) return false; // Ignore RHS; return true; } 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; CharUnits AdditionalOffset = CharUnits::fromQuantity( RHSVal.getInt().getZExtValue()); if (E->getOpcode() == BO_Add) Result.getLValueOffset() += AdditionalOffset; else Result.getLValueOffset() -= AdditionalOffset; return true; } // Handle cases like 4 + (unsigned long)&a if (E->getOpcode() == BO_Add && RHSVal.isLValue() && LHSVal.isInt()) { Result = RHSVal; Result.getLValueOffset() += CharUnits::fromQuantity( LHSVal.getInt().getZExtValue()); 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 following cases expect both operands to be an integer if (!LHSVal.isInt() || !RHSVal.isInt()) return Error(E); const APSInt &LHS = LHSVal.getInt(); APSInt RHS = RHSVal.getInt(); switch (E->getOpcode()) { default: return Error(E); case BO_Mul: return Success(CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, std::multiplies()), E, Result); case BO_Add: return Success(CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, std::plus()), E, Result); case BO_Sub: return Success(CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, std::minus()), E, Result); case BO_And: return Success(LHS & RHS, E, Result); case BO_Xor: return Success(LHS ^ RHS, E, Result); case BO_Or: return Success(LHS | RHS, E, Result); case BO_Div: case BO_Rem: if (RHS == 0) return Error(E, diag::note_expr_divide_by_zero); // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. The latter is // not actually undefined behavior in C++11 due to a language defect. if (RHS.isNegative() && RHS.isAllOnesValue() && LHS.isSigned() && LHS.isMinSignedValue()) HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType()); return Success(E->getOpcode() == BO_Rem ? LHS % RHS : LHS / RHS, E, Result); case BO_Shl: { // During constant-folding, a negative shift is an opposite shift. Such // a shift is not a constant expression. if (RHS.isSigned() && RHS.isNegative()) { 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) { CCEDiag(E, diag::note_constexpr_large_shift) << RHS << E->getType() << LHS.getBitWidth(); } else if (LHS.isSigned()) { // C++11 [expr.shift]p2: A signed left shift must have a non-negative // operand, and must not overflow the corresponding unsigned type. if (LHS.isNegative()) CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; else if (LHS.countLeadingZeros() < SA) CCEDiag(E, diag::note_constexpr_lshift_discards); } return Success(LHS << SA, E, Result); } case BO_Shr: { // During constant-folding, a negative shift is an opposite shift. Such a // shift is not a constant expression. if (RHS.isSigned() && RHS.isNegative()) { 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) CCEDiag(E, diag::note_constexpr_large_shift) << RHS << E->getType() << LHS.getBitWidth(); return Success(LHS >> SA, E, Result); } case BO_LT: return Success(LHS < RHS, E, Result); case BO_GT: return Success(LHS > RHS, E, Result); case BO_LE: return Success(LHS <= RHS, E, Result); case BO_GE: return Success(LHS >= RHS, E, Result); case BO_EQ: return Success(LHS == RHS, E, Result); case BO_NE: return Success(LHS != RHS, 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!"); } bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { if (E->isAssignmentOp()) return Error(E); if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); QualType LHSTy = E->getLHS()->getType(); QualType RHSTy = E->getRHS()->getType(); if (LHSTy->isAnyComplexType()) { assert(RHSTy->isAnyComplexType() && "Invalid comparison"); ComplexValue LHS, RHS; bool LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); if (!LHSOK && !Info.keepEvaluatingAfterFailure()) return false; 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()); if (E->getOpcode() == BO_EQ) return Success((CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual), E); else { assert(E->getOpcode() == BO_NE && "Invalid complex comparison."); return Success(((CR_r == APFloat::cmpGreaterThan || CR_r == APFloat::cmpLessThan || CR_r == APFloat::cmpUnordered) || (CR_i == APFloat::cmpGreaterThan || CR_i == APFloat::cmpLessThan || CR_i == APFloat::cmpUnordered)), E); } } else { if (E->getOpcode() == BO_EQ) return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() && LHS.getComplexIntImag() == RHS.getComplexIntImag()), E); else { assert(E->getOpcode() == BO_NE && "Invalid compex comparison."); return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() || LHS.getComplexIntImag() != RHS.getComplexIntImag()), E); } } } if (LHSTy->isRealFloatingType() && RHSTy->isRealFloatingType()) { APFloat RHS(0.0), LHS(0.0); bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); if (!LHSOK && !Info.keepEvaluatingAfterFailure()) return false; if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) return false; APFloat::cmpResult CR = LHS.compare(RHS); switch (E->getOpcode()) { default: llvm_unreachable("Invalid binary operator!"); case BO_LT: return Success(CR == APFloat::cmpLessThan, E); case BO_GT: return Success(CR == APFloat::cmpGreaterThan, E); case BO_LE: return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E); case BO_GE: return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual, E); case BO_EQ: return Success(CR == APFloat::cmpEqual, E); case BO_NE: return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpLessThan || CR == APFloat::cmpUnordered, E); } } if (LHSTy->isPointerType() && RHSTy->isPointerType()) { if (E->getOpcode() == BO_Sub || E->isComparisonOp()) { LValue LHSValue, RHSValue; bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); if (!LHSOK && Info.keepEvaluatingAfterFailure()) 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)) { if (E->getOpcode() == BO_Sub) { // Handle &&A - &&B. if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) return false; const Expr *LHSExpr = LHSValue.Base.dyn_cast(); const Expr *RHSExpr = LHSValue.Base.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; } // Inequalities and subtractions between unrelated pointers have // unspecified or undefined behavior. if (!E->isEqualityOp()) 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); // Pointers with different bases cannot represent the same object. // (Note that clang defaults to -fmerge-all-constants, which can // lead to inconsistent results for comparisons involving the address // of a constant; this generally doesn't matter in practice.) return Success(E->getOpcode() == BO_NE, E); } const CharUnits &LHSOffset = LHSValue.getLValueOffset(); const CharUnits &RHSOffset = RHSValue.getLValueOffset(); SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); if (E->getOpcode() == BO_Sub) { // 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)) 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; // 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 Success(Result, E); } // 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 && E->isRelationalOp()) 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 && E->isRelationalOp()) { 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) CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); else if (!LF) CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) << getAsBaseClass(LHSDesignator.Entries[Mismatch]) << RF->getParent() << RF; else if (!RF) 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()) 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() && E->isRelationalOp()) { 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); } switch (E->getOpcode()) { default: llvm_unreachable("missing comparison operator"); case BO_LT: return Success(CompareLHS < CompareRHS, E); case BO_GT: return Success(CompareLHS > CompareRHS, E); case BO_LE: return Success(CompareLHS <= CompareRHS, E); case BO_GE: return Success(CompareLHS >= CompareRHS, E); case BO_EQ: return Success(CompareLHS == CompareRHS, E); case BO_NE: return Success(CompareLHS != CompareRHS, E); } } } if (LHSTy->isMemberPointerType()) { assert(E->isEqualityOp() && "unexpected member pointer operation"); assert(RHSTy->isMemberPointerType() && "invalid comparison"); MemberPtr LHSValue, RHSValue; bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); if (!LHSOK && Info.keepEvaluatingAfterFailure()) 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(E->getOpcode() == BO_EQ ? Equal : !Equal, 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()) CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; if (const CXXMethodDecl *MD = dyn_cast(RHSValue.getDecl())) if (MD->isVirtual()) 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(E->getOpcode() == BO_EQ ? Equal : !Equal, 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. BinaryOperator::Opcode Opcode = E->getOpcode(); return Success(Opcode == BO_EQ || Opcode == BO_LE || Opcode == BO_GE, E); } assert((!LHSTy->isIntegralOrEnumerationType() || !RHSTy->isIntegralOrEnumerationType()) && "DataRecursiveIntBinOpEvaluator should have handled integral types"); // We can't continue from here for non-integral types. return ExprEvaluatorBaseTy::VisitBinaryOperator(E); } CharUnits IntExprEvaluator::GetAlignOfType(QualType T) { // C++ [expr.alignof]p3: "When alignof is applied to a reference type, the // result shall be the alignment of the referenced type." if (const ReferenceType *Ref = T->getAs()) T = Ref->getPointeeType(); // __alignof is defined to return the preferred alignment. return Info.Ctx.toCharUnitsFromBits( Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); } CharUnits IntExprEvaluator::GetAlignOfExpr(const Expr *E) { E = E->IgnoreParens(); // 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(E->getType()); } /// 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_AlignOf: { if (E->isArgumentType()) return Success(GetAlignOfType(E->getArgumentType()), E); else return Success(GetAlignOfExpr(E->getArgumentExpr()), E); } case UETT_VecStep: { QualType Ty = E->getTypeOfArgument(); if (Ty->isVectorType()) { unsigned n = Ty->getAs()->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); } } 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) { OffsetOfExpr::OffsetOfNode ON = OOE->getComponent(i); switch (ON.getKind()) { case OffsetOfExpr::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 OffsetOfExpr::OffsetOfNode::Field: { FieldDecl *MemberDecl = ON.getField(); const RecordType *RT = CurrentType->getAs(); if (!RT) return Error(OOE); RecordDecl *RD = RT->getDecl(); 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 OffsetOfExpr::OffsetOfNode::Identifier: llvm_unreachable("dependent __builtin_offsetof"); case OffsetOfExpr::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(); 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()) HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), E->getType()); 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: 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_NonAtomicToAtomic: case CK_NoOp: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_MemberPointerToBoolean: case CK_PointerToBoolean: case CK_IntegralToBoolean: case CK_FloatingToBoolean: case CK_FloatingComplexToBoolean: case CK_IntegralComplexToBoolean: { bool BoolResult; if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) return false; return Success(BoolResult, 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 = Info.Ctx.MakeIntValue(LV.getLValueOffset().getQuantity(), SrcType); 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); } //===----------------------------------------------------------------------===// // 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 (SNaN) Result = llvm::APFloat::getSNaN(Sem, false, &fill); else Result = llvm::APFloat::getQNaN(Sem, false, &fill); return true; } bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { switch (E->isBuiltinCall()) { 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_inf: case Builtin::BI__builtin_inff: case Builtin::BI__builtin_infl: { 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: 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: // 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: if (!EvaluateFloat(E->getArg(0), Result, Info)) return false; if (Result.isNegative()) Result.changeSign(); return true; case Builtin::BI__builtin_copysign: case Builtin::BI__builtin_copysignf: case Builtin::BI__builtin_copysignl: { 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.keepEvaluatingAfterFailure()) return false; if (!EvaluateFloat(E->getRHS(), RHS, Info) || !LHSOK) return false; switch (E->getOpcode()) { default: return Error(E); case BO_Mul: Result.multiply(RHS, APFloat::rmNearestTiesToEven); break; case BO_Add: Result.add(RHS, APFloat::rmNearestTiesToEven); break; case BO_Sub: Result.subtract(RHS, APFloat::rmNearestTiesToEven); break; case BO_Div: Result.divide(RHS, APFloat::rmNearestTiesToEven); break; } if (Result.isInfinity() || Result.isNaN()) CCEDiag(E, diag::note_constexpr_float_arithmetic) << Result.isNaN(); return true; } 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()->getAs()->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_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: llvm_unreachable("invalid cast kind for complex value"); case CK_LValueToRValue: case CK_AtomicToNonAtomic: case CK_NonAtomicToAtomic: case CK_NoOp: 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()->getAs()->getElementType(); QualType From = E->getSubExpr()->getType()->getAs()->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); bool LHSOK = Visit(E->getLHS()); if (!LHSOK && !Info.keepEvaluatingAfterFailure()) return false; ComplexValue RHS; if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) return false; assert(Result.isComplexFloat() == RHS.isComplexFloat() && "Invalid operands to binary operator."); switch (E->getOpcode()) { default: return Error(E); case BO_Add: if (Result.isComplexFloat()) { Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), APFloat::rmNearestTiesToEven); 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); Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), APFloat::rmNearestTiesToEven); } else { Result.getComplexIntReal() -= RHS.getComplexIntReal(); Result.getComplexIntImag() -= RHS.getComplexIntImag(); } break; case BO_Mul: if (Result.isComplexFloat()) { ComplexValue LHS = Result; APFloat &LHS_r = LHS.getComplexFloatReal(); APFloat &LHS_i = LHS.getComplexFloatImag(); APFloat &RHS_r = RHS.getComplexFloatReal(); APFloat &RHS_i = RHS.getComplexFloatImag(); APFloat Tmp = LHS_r; Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); Result.getComplexFloatReal() = Tmp; Tmp = LHS_i; Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); Result.getComplexFloatReal().subtract(Tmp, APFloat::rmNearestTiesToEven); Tmp = LHS_r; Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); Result.getComplexFloatImag() = Tmp; Tmp = LHS_i; Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); Result.getComplexFloatImag().add(Tmp, APFloat::rmNearestTiesToEven); } 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()) { ComplexValue LHS = Result; APFloat &LHS_r = LHS.getComplexFloatReal(); APFloat &LHS_i = LHS.getComplexFloatImag(); APFloat &RHS_r = RHS.getComplexFloatReal(); APFloat &RHS_i = RHS.getComplexFloatImag(); APFloat &Res_r = Result.getComplexFloatReal(); APFloat &Res_i = Result.getComplexFloatImag(); APFloat Den = RHS_r; Den.multiply(RHS_r, APFloat::rmNearestTiesToEven); APFloat Tmp = RHS_i; Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); Den.add(Tmp, APFloat::rmNearestTiesToEven); Res_r = LHS_r; Res_r.multiply(RHS_r, APFloat::rmNearestTiesToEven); Tmp = LHS_i; Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); Res_r.add(Tmp, APFloat::rmNearestTiesToEven); Res_r.divide(Den, APFloat::rmNearestTiesToEven); Res_i = LHS_i; Res_i.multiply(RHS_r, APFloat::rmNearestTiesToEven); Tmp = LHS_r; Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); Res_i.subtract(Tmp, APFloat::rmNearestTiesToEven); Res_i.divide(Den, APFloat::rmNearestTiesToEven); } 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); } //===----------------------------------------------------------------------===// // 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 VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_ToVoid: VisitIgnoredValue(E->getSubExpr()); 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. if (E->isGLValue() || E->getType()->isFunctionType()) { LValue LV; if (!EvaluateLValue(E, LV, Info)) return false; LV.moveInto(Result); } else if (E->getType()->isVectorType()) { if (!EvaluateVector(E, Result, Info)) return false; } else if (E->getType()->isIntegralOrEnumerationType()) { if (!IntExprEvaluator(Info, Result).Visit(E)) return false; } else if (E->getType()->hasPointerRepresentation()) { LValue LV; if (!EvaluatePointer(E, LV, Info)) return false; LV.moveInto(Result); } else if (E->getType()->isRealFloatingType()) { llvm::APFloat F(0.0); if (!EvaluateFloat(E, F, Info)) return false; Result = APValue(F); } else if (E->getType()->isAnyComplexType()) { ComplexValue C; if (!EvaluateComplex(E, C, Info)) return false; C.moveInto(Result); } else if (E->getType()->isMemberPointerType()) { MemberPtr P; if (!EvaluateMemberPointer(E, P, Info)) return false; P.moveInto(Result); return true; } else if (E->getType()->isArrayType()) { LValue LV; LV.set(E, Info.CurrentCall->Index); if (!EvaluateArray(E, LV, Info.CurrentCall->Temporaries[E], Info)) return false; Result = Info.CurrentCall->Temporaries[E]; } else if (E->getType()->isRecordType()) { LValue LV; LV.set(E, Info.CurrentCall->Index); if (!EvaluateRecord(E, LV, Info.CurrentCall->Temporaries[E], Info)) return false; Result = Info.CurrentCall->Temporaries[E]; } else if (E->getType()->isVoidType()) { if (Info.getLangOpts().CPlusPlus0x) Info.CCEDiag(E, diag::note_constexpr_nonliteral) << E->getType(); else Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); if (!EvaluateVoid(E, Info)) return false; } else if (Info.getLangOpts().CPlusPlus0x) { Info.Diag(E, diag::note_constexpr_nonliteral) << E->getType(); return false; } else { Info.Diag(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, CheckConstantExpressionKind CCEK, bool AllowNonLiteralTypes) { if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E)) 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. if (E->getType()->isArrayType()) return EvaluateArray(E, This, Result, Info); else if (E->getType()->isRecordType()) return EvaluateRecord(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 (!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); } /// 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) const { // Fast-path evaluations of integer literals, since we sometimes see files // containing vast quantities of these. if (const IntegerLiteral *L = dyn_cast(this)) { Result.Val = APValue(APSInt(L->getValue(), L->getType()->isUnsignedIntegerType())); return true; } // FIXME: Evaluating values of 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().CPlusPlus0x) return false; EvalInfo Info(Ctx, Result); return ::EvaluateAsRValue(Info, this, Result.Val); } bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx) const { EvalResult Scratch; return EvaluateAsRValue(Scratch, Ctx) && HandleConversionToBool(Scratch.Val, Result); } bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx, SideEffectsKind AllowSideEffects) const { if (!getType()->isIntegralOrEnumerationType()) return false; EvalResult ExprResult; if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isInt() || (!AllowSideEffects && ExprResult.HasSideEffects)) return false; Result = ExprResult.Val.getInt(); return true; } bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const { EvalInfo Info(Ctx, Result); LValue LV; if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || !CheckLValueConstantExpression(Info, getExprLoc(), Ctx.getLValueReferenceType(getType()), LV)) return false; LV.moveInto(Result.Val); return true; } bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, const VarDecl *VD, llvm::SmallVectorImpl &Notes) const { // 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().CPlusPlus0x) return false; Expr::EvalStatus EStatus; EStatus.Diag = &Notes; EvalInfo InitInfo(Ctx, EStatus); InitInfo.setEvaluatingDecl(VD, Value); 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, CCEK_Constant, /*AllowNonLiteralTypes=*/true)) return false; } if (!EvaluateInPlace(Value, InitInfo, LVal, this, CCEK_Constant, /*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) const { EvalResult Result; return EvaluateAsRValue(Result, Ctx) && !Result.HasSideEffects; } bool Expr::HasSideEffects(const ASTContext &Ctx) const { return HasSideEffect(Ctx).Visit(this); } APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx) const { EvalResult EvalResult; bool Result = EvaluateAsRValue(EvalResult, Ctx); (void)Result; assert(Result && "Could not evaluate expression"); assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer"); return EvalResult.Val.getInt(); } 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 /// /// FIXME: Handle offsetof. Two things to do: Handle GCC's __builtin_offsetof /// to support gcc 4.0+ and handle the idiom GCC recognizes with a null pointer /// cast+dereference. // CheckICE - This function does the fundamental ICE checking: the returned // ICEDiag contains a Val of 0, 1, or 2, and a possibly null SourceLocation. // 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 Evalute. // // Meanings of Val: // 0: This expression is an ICE. // 1: 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. // 2: This expression is not an ICE, and is not a legal subexpression for one. namespace { struct ICEDiag { unsigned Val; SourceLocation Loc; public: ICEDiag(unsigned v, SourceLocation l) : Val(v), Loc(l) {} ICEDiag() : Val(0) {} }; } static ICEDiag NoDiag() { return ICEDiag(); } static ICEDiag CheckEvalInICE(const Expr* E, ASTContext &Ctx) { Expr::EvalResult EVResult; if (!E->EvaluateAsRValue(EVResult, Ctx) || EVResult.HasSideEffects || !EVResult.Val.isInt()) { return ICEDiag(2, E->getLocStart()); } return NoDiag(); } static ICEDiag CheckICE(const Expr* E, ASTContext &Ctx) { assert(!E->isValueDependent() && "Should not see value dependent exprs!"); if (!E->getType()->isIntegralOrEnumerationType()) { return ICEDiag(2, E->getLocStart()); } 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::MemberExprClass: case Expr::CompoundAssignOperatorClass: case Expr::CompoundLiteralExprClass: case Expr::ExtVectorElementExprClass: case Expr::DesignatedInitExprClass: 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::CXXNullPtrLiteralExprClass: case Expr::UserDefinedLiteralClass: case Expr::CXXThisExprClass: case Expr::CXXThrowExprClass: case Expr::CXXNewExprClass: case Expr::CXXDeleteExprClass: case Expr::CXXPseudoDestructorExprClass: case Expr::UnresolvedLookupExprClass: case Expr::DependentScopeDeclRefExprClass: case Expr::CXXConstructExprClass: case Expr::CXXBindTemporaryExprClass: case Expr::ExprWithCleanupsClass: case Expr::CXXTemporaryObjectExprClass: case Expr::CXXUnresolvedConstructExprClass: case Expr::CXXDependentScopeMemberExprClass: case Expr::UnresolvedMemberExprClass: case Expr::ObjCStringLiteralClass: case Expr::ObjCNumericLiteralClass: 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::ShuffleVectorExprClass: case Expr::BlockExprClass: case Expr::NoStmtClass: case Expr::OpaqueValueExprClass: case Expr::PackExpansionExprClass: case Expr::SubstNonTypeTemplateParmPackExprClass: case Expr::AsTypeExprClass: case Expr::ObjCIndirectCopyRestoreExprClass: case Expr::MaterializeTemporaryExprClass: case Expr::PseudoObjectExprClass: case Expr::AtomicExprClass: case Expr::InitListExprClass: case Expr::LambdaExprClass: return ICEDiag(2, E->getLocStart()); case Expr::SizeOfPackExprClass: case Expr::GNUNullExprClass: // GCC considers the GNU __null value to be an integral constant expression. return NoDiag(); case Expr::SubstNonTypeTemplateParmExprClass: return CheckICE(cast(E)->getReplacement(), Ctx); case Expr::ParenExprClass: return CheckICE(cast(E)->getSubExpr(), Ctx); case Expr::GenericSelectionExprClass: return CheckICE(cast(E)->getResultExpr(), Ctx); case Expr::IntegerLiteralClass: case Expr::CharacterLiteralClass: case Expr::ObjCBoolLiteralExprClass: case Expr::CXXBoolLiteralExprClass: case Expr::CXXScalarValueInitExprClass: case Expr::UnaryTypeTraitExprClass: case Expr::BinaryTypeTraitExprClass: 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->isBuiltinCall()) return CheckEvalInICE(E, Ctx); return ICEDiag(2, E->getLocStart()); } case Expr::DeclRefExprClass: { if (isa(cast(E)->getDecl())) return NoDiag(); const ValueDecl *D = dyn_cast(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(2, 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(2, 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(2, cast(E)->getLocation()); } } return ICEDiag(2, E->getLocStart()); } 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: // 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(2, E->getLocStart()); 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); } // OffsetOf falls through here. } 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(2, E->getLocStart()); 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(2, E->getLocStart()); 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: { 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.Val == 0 && RHSResult.Val == 0) { llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); if (REval == 0) return ICEDiag(1, E->getLocStart()); if (REval.isSigned() && REval.isAllOnesValue()) { llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); if (LEval.isMinSignedValue()) return ICEDiag(1, E->getLocStart()); } } } 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.Val == 0 && RHSResult.Val == 0) return ICEDiag(1, E->getLocStart()); } else { // In both C89 and C++, commas in ICEs are illegal. return ICEDiag(2, E->getLocStart()); } } if (LHSResult.Val >= RHSResult.Val) return LHSResult; return RHSResult; } case BO_LAnd: case BO_LOr: { ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); if (LHSResult.Val == 0 && RHSResult.Val == 1) { // 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(); } if (LHSResult.Val >= RHSResult.Val) return LHSResult; return RHSResult; } } } 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(2, E->getLocStart()); 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(2, E->getLocStart()); } } case Expr::BinaryConditionalOperatorClass: { const BinaryConditionalOperator *Exp = cast(E); ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); if (CommonResult.Val == 2) return CommonResult; ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); if (FalseResult.Val == 2) return FalseResult; if (CommonResult.Val == 1) return CommonResult; if (FalseResult.Val == 1 && 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->isBuiltinCall() == Builtin::BI__builtin_constant_p) return CheckEvalInICE(E, Ctx); ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); if (CondResult.Val == 2) return CondResult; ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); if (TrueResult.Val == 2) return TrueResult; if (FalseResult.Val == 2) return FalseResult; if (CondResult.Val == 1) return CondResult; if (TrueResult.Val == 0 && FalseResult.Val == 0) 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::ChooseExprClass: { return CheckICE(cast(E)->getChosenSubExpr(Ctx), Ctx); } } llvm_unreachable("Invalid StmtClass!"); } /// Evaluate an expression as a C++11 integral constant expression. static bool EvaluateCPlusPlus11IntegralConstantExpr(ASTContext &Ctx, const Expr *E, llvm::APSInt *Value, SourceLocation *Loc) { if (!E->getType()->isIntegralOrEnumerationType()) { if (Loc) *Loc = E->getExprLoc(); return false; } APValue Result; if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) return false; assert(Result.isInt() && "pointer cast to int is not an ICE"); if (Value) *Value = Result.getInt(); return true; } bool Expr::isIntegerConstantExpr(ASTContext &Ctx, SourceLocation *Loc) const { if (Ctx.getLangOpts().CPlusPlus0x) return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, 0, Loc); ICEDiag d = CheckICE(this, Ctx); if (d.Val != 0) { if (Loc) *Loc = d.Loc; return false; } return true; } bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, ASTContext &Ctx, SourceLocation *Loc, bool isEvaluated) const { if (Ctx.getLangOpts().CPlusPlus0x) return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); if (!isIntegerConstantExpr(Ctx, Loc)) return false; if (!EvaluateAsInt(Value, Ctx)) llvm_unreachable("ICE cannot be evaluated!"); return true; } bool Expr::isCXX98IntegralConstantExpr(ASTContext &Ctx) const { return CheckICE(this, Ctx).Val == 0; } bool Expr::isCXX11ConstantExpr(ASTContext &Ctx, APValue *Result, SourceLocation *Loc) const { // We support this checking in C++98 mode in order to diagnose compatibility // issues. assert(Ctx.getLangOpts().CPlusPlus); // Build evaluation settings. Expr::EvalStatus Status; llvm::SmallVector Diags; Status.Diag = &Diags; EvalInfo Info(Ctx, Status); 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::isPotentialConstantExpr(const FunctionDecl *FD, llvm::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); Info.CheckingPotentialConstantExpression = true; const CXXMethodDecl *MD = dyn_cast(FD); const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : 0; // FIXME: 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; SourceLocation Loc = FD->getLocation(); APValue Scratch; if (const CXXConstructorDecl *CD = dyn_cast(FD)) HandleConstructorCall(Loc, This, Args, CD, Info, Scratch); else HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : 0, Args, FD->getBody(), Info, Scratch); return Diags.empty(); }