1 //===- ScopeInfo.h - Information about a semantic context -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines FunctionScopeInfo and its subclasses, which contain
11 // information about a single function, block, lambda, or method body.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_SEMA_SCOPEINFO_H
16 #define LLVM_CLANG_SEMA_SCOPEINFO_H
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/Type.h"
20 #include "clang/Basic/CapturedStmt.h"
21 #include "clang/Basic/LLVM.h"
22 #include "clang/Basic/PartialDiagnostic.h"
23 #include "clang/Basic/SourceLocation.h"
24 #include "clang/Sema/CleanupInfo.h"
25 #include "llvm/ADT/DenseMap.h"
26 #include "llvm/ADT/DenseMapInfo.h"
27 #include "llvm/ADT/MapVector.h"
28 #include "llvm/ADT/PointerIntPair.h"
29 #include "llvm/ADT/SmallPtrSet.h"
30 #include "llvm/ADT/SmallSet.h"
31 #include "llvm/ADT/SmallVector.h"
32 #include "llvm/ADT/StringRef.h"
33 #include "llvm/ADT/StringSwitch.h"
34 #include "llvm/Support/Casting.h"
35 #include "llvm/Support/ErrorHandling.h"
46 class ImplicitParamDecl;
48 class ObjCIvarRefExpr;
49 class ObjCMessageExpr;
50 class ObjCPropertyDecl;
51 class ObjCPropertyRefExpr;
58 class TemplateParameterList;
59 class TemplateTypeParmDecl;
64 /// Contains information about the compound statement currently being
66 class CompoundScopeInfo {
68 /// Whether this compound stamement contains `for' or `while' loops
69 /// with empty bodies.
70 bool HasEmptyLoopBodies = false;
72 /// Whether this compound statement corresponds to a GNU statement
76 CompoundScopeInfo(bool IsStmtExpr) : IsStmtExpr(IsStmtExpr) {}
78 void setHasEmptyLoopBodies() {
79 HasEmptyLoopBodies = true;
83 class PossiblyUnreachableDiag {
89 PossiblyUnreachableDiag(const PartialDiagnostic &PD, SourceLocation Loc,
91 : PD(PD), Loc(Loc), stmt(stmt) {}
94 /// Retains information about a function, method, or block that is
95 /// currently being parsed.
96 class FunctionScopeInfo {
106 /// What kind of scope we are describing.
109 /// Whether this function contains a VLA, \@try, try, C++
110 /// initializer, or anything else that can't be jumped past.
111 bool HasBranchProtectedScope : 1;
113 /// Whether this function contains any switches or direct gotos.
114 bool HasBranchIntoScope : 1;
116 /// Whether this function contains any indirect gotos.
117 bool HasIndirectGoto : 1;
119 /// Whether a statement was dropped because it was invalid.
120 bool HasDroppedStmt : 1;
122 /// True if current scope is for OpenMP declare reduction combiner.
123 bool HasOMPDeclareReductionCombiner : 1;
125 /// Whether there is a fallthrough statement in this function.
126 bool HasFallthroughStmt : 1;
128 /// Whether we make reference to a declaration that could be
130 bool HasPotentialAvailabilityViolations : 1;
132 /// A flag that is set when parsing a method that must call super's
133 /// implementation, such as \c -dealloc, \c -finalize, or any method marked
134 /// with \c __attribute__((objc_requires_super)).
135 bool ObjCShouldCallSuper : 1;
137 /// True when this is a method marked as a designated initializer.
138 bool ObjCIsDesignatedInit : 1;
140 /// This starts true for a method marked as designated initializer and will
141 /// be set to false if there is an invocation to a designated initializer of
143 bool ObjCWarnForNoDesignatedInitChain : 1;
145 /// True when this is an initializer method not marked as a designated
146 /// initializer within a class that has at least one initializer marked as a
147 /// designated initializer.
148 bool ObjCIsSecondaryInit : 1;
150 /// This starts true for a secondary initializer method and will be set to
151 /// false if there is an invocation of an initializer on 'self'.
152 bool ObjCWarnForNoInitDelegation : 1;
154 /// True only when this function has not already built, or attempted
155 /// to build, the initial and final coroutine suspend points
156 bool NeedsCoroutineSuspends : 1;
158 /// An enumeration represeting the kind of the first coroutine statement
159 /// in the function. One of co_return, co_await, or co_yield.
160 unsigned char FirstCoroutineStmtKind : 2;
162 /// First coroutine statement in the current function.
163 /// (ex co_return, co_await, co_yield)
164 SourceLocation FirstCoroutineStmtLoc;
166 /// First 'return' statement in the current function.
167 SourceLocation FirstReturnLoc;
169 /// First C++ 'try' statement in the current function.
170 SourceLocation FirstCXXTryLoc;
172 /// First SEH '__try' statement in the current function.
173 SourceLocation FirstSEHTryLoc;
175 /// Used to determine if errors occurred in this function or block.
176 DiagnosticErrorTrap ErrorTrap;
178 /// A SwitchStmt, along with a flag indicating if its list of case statements
179 /// is incomplete (because we dropped an invalid one while parsing).
180 using SwitchInfo = llvm::PointerIntPair<SwitchStmt*, 1, bool>;
182 /// SwitchStack - This is the current set of active switch statements in the
184 SmallVector<SwitchInfo, 8> SwitchStack;
186 /// The list of return statements that occur within the function or
187 /// block, if there is any chance of applying the named return value
188 /// optimization, or if we need to infer a return type.
189 SmallVector<ReturnStmt*, 4> Returns;
191 /// The promise object for this coroutine, if any.
192 VarDecl *CoroutinePromise = nullptr;
194 /// A mapping between the coroutine function parameters that were moved
195 /// to the coroutine frame, and their move statements.
196 llvm::SmallMapVector<ParmVarDecl *, Stmt *, 4> CoroutineParameterMoves;
198 /// The initial and final coroutine suspend points.
199 std::pair<Stmt *, Stmt *> CoroutineSuspends;
201 /// The stack of currently active compound stamement scopes in the
203 SmallVector<CompoundScopeInfo, 4> CompoundScopes;
205 /// A list of PartialDiagnostics created but delayed within the
206 /// current function scope. These diagnostics are vetted for reachability
207 /// prior to being emitted.
208 SmallVector<PossiblyUnreachableDiag, 4> PossiblyUnreachableDiags;
210 /// A list of parameters which have the nonnull attribute and are
211 /// modified in the function.
212 llvm::SmallPtrSet<const ParmVarDecl *, 8> ModifiedNonNullParams;
215 /// Represents a simple identification of a weak object.
217 /// Part of the implementation of -Wrepeated-use-of-weak.
219 /// This is used to determine if two weak accesses refer to the same object.
220 /// Here are some examples of how various accesses are "profiled":
222 /// Access Expression | "Base" Decl | "Property" Decl
223 /// :---------------: | :-----------------: | :------------------------------:
224 /// self.property | self (VarDecl) | property (ObjCPropertyDecl)
225 /// self.implicitProp | self (VarDecl) | -implicitProp (ObjCMethodDecl)
226 /// self->ivar.prop | ivar (ObjCIvarDecl) | prop (ObjCPropertyDecl)
227 /// cxxObj.obj.prop | obj (FieldDecl) | prop (ObjCPropertyDecl)
228 /// [self foo].prop | 0 (unknown) | prop (ObjCPropertyDecl)
229 /// self.prop1.prop2 | prop1 (ObjCPropertyDecl) | prop2 (ObjCPropertyDecl)
230 /// MyClass.prop | MyClass (ObjCInterfaceDecl) | -prop (ObjCMethodDecl)
231 /// MyClass.foo.prop | +foo (ObjCMethodDecl) | -prop (ObjCPropertyDecl)
232 /// weakVar | 0 (known) | weakVar (VarDecl)
233 /// self->weakIvar | self (VarDecl) | weakIvar (ObjCIvarDecl)
235 /// Objects are identified with only two Decls to make it reasonably fast to
237 class WeakObjectProfileTy {
238 /// The base object decl, as described in the class documentation.
240 /// The extra flag is "true" if the Base and Property are enough to uniquely
241 /// identify the object in memory.
243 /// \sa isExactProfile()
244 using BaseInfoTy = llvm::PointerIntPair<const NamedDecl *, 1, bool>;
247 /// The "property" decl, as described in the class documentation.
249 /// Note that this may not actually be an ObjCPropertyDecl, e.g. in the
250 /// case of "implicit" properties (regular methods accessed via dot syntax).
251 const NamedDecl *Property = nullptr;
253 /// Used to find the proper base profile for a given base expression.
254 static BaseInfoTy getBaseInfo(const Expr *BaseE);
256 inline WeakObjectProfileTy();
257 static inline WeakObjectProfileTy getSentinel();
260 WeakObjectProfileTy(const ObjCPropertyRefExpr *RE);
261 WeakObjectProfileTy(const Expr *Base, const ObjCPropertyDecl *Property);
262 WeakObjectProfileTy(const DeclRefExpr *RE);
263 WeakObjectProfileTy(const ObjCIvarRefExpr *RE);
265 const NamedDecl *getBase() const { return Base.getPointer(); }
266 const NamedDecl *getProperty() const { return Property; }
268 /// Returns true if the object base specifies a known object in memory,
269 /// rather than, say, an instance variable or property of another object.
271 /// Note that this ignores the effects of aliasing; that is, \c foo.bar is
272 /// considered an exact profile if \c foo is a local variable, even if
273 /// another variable \c foo2 refers to the same object as \c foo.
275 /// For increased precision, accesses with base variables that are
276 /// properties or ivars of 'self' (e.g. self.prop1.prop2) are considered to
277 /// be exact, though this is not true for arbitrary variables
278 /// (foo.prop1.prop2).
279 bool isExactProfile() const {
280 return Base.getInt();
283 bool operator==(const WeakObjectProfileTy &Other) const {
284 return Base == Other.Base && Property == Other.Property;
287 // For use in DenseMap.
288 // We can't specialize the usual llvm::DenseMapInfo at the end of the file
289 // because by that point the DenseMap in FunctionScopeInfo has already been
293 static inline WeakObjectProfileTy getEmptyKey() {
294 return WeakObjectProfileTy();
297 static inline WeakObjectProfileTy getTombstoneKey() {
298 return WeakObjectProfileTy::getSentinel();
301 static unsigned getHashValue(const WeakObjectProfileTy &Val) {
302 using Pair = std::pair<BaseInfoTy, const NamedDecl *>;
304 return llvm::DenseMapInfo<Pair>::getHashValue(Pair(Val.Base,
308 static bool isEqual(const WeakObjectProfileTy &LHS,
309 const WeakObjectProfileTy &RHS) {
315 /// Represents a single use of a weak object.
317 /// Stores both the expression and whether the access is potentially unsafe
318 /// (i.e. it could potentially be warned about).
320 /// Part of the implementation of -Wrepeated-use-of-weak.
322 llvm::PointerIntPair<const Expr *, 1, bool> Rep;
325 WeakUseTy(const Expr *Use, bool IsRead) : Rep(Use, IsRead) {}
327 const Expr *getUseExpr() const { return Rep.getPointer(); }
328 bool isUnsafe() const { return Rep.getInt(); }
329 void markSafe() { Rep.setInt(false); }
331 bool operator==(const WeakUseTy &Other) const {
332 return Rep == Other.Rep;
336 /// Used to collect uses of a particular weak object in a function body.
338 /// Part of the implementation of -Wrepeated-use-of-weak.
339 using WeakUseVector = SmallVector<WeakUseTy, 4>;
341 /// Used to collect all uses of weak objects in a function body.
343 /// Part of the implementation of -Wrepeated-use-of-weak.
344 using WeakObjectUseMap =
345 llvm::SmallDenseMap<WeakObjectProfileTy, WeakUseVector, 8,
346 WeakObjectProfileTy::DenseMapInfo>;
349 /// Used to collect all uses of weak objects in this function body.
351 /// Part of the implementation of -Wrepeated-use-of-weak.
352 WeakObjectUseMap WeakObjectUses;
355 FunctionScopeInfo(const FunctionScopeInfo&) = default;
358 FunctionScopeInfo(DiagnosticsEngine &Diag)
359 : Kind(SK_Function), HasBranchProtectedScope(false),
360 HasBranchIntoScope(false), HasIndirectGoto(false),
361 HasDroppedStmt(false), HasOMPDeclareReductionCombiner(false),
362 HasFallthroughStmt(false), HasPotentialAvailabilityViolations(false),
363 ObjCShouldCallSuper(false), ObjCIsDesignatedInit(false),
364 ObjCWarnForNoDesignatedInitChain(false), ObjCIsSecondaryInit(false),
365 ObjCWarnForNoInitDelegation(false), NeedsCoroutineSuspends(true),
368 virtual ~FunctionScopeInfo();
370 /// Record that a weak object was accessed.
372 /// Part of the implementation of -Wrepeated-use-of-weak.
373 template <typename ExprT>
374 inline void recordUseOfWeak(const ExprT *E, bool IsRead = true);
376 void recordUseOfWeak(const ObjCMessageExpr *Msg,
377 const ObjCPropertyDecl *Prop);
379 /// Record that a given expression is a "safe" access of a weak object (e.g.
380 /// assigning it to a strong variable.)
382 /// Part of the implementation of -Wrepeated-use-of-weak.
383 void markSafeWeakUse(const Expr *E);
385 const WeakObjectUseMap &getWeakObjectUses() const {
386 return WeakObjectUses;
389 void setHasBranchIntoScope() {
390 HasBranchIntoScope = true;
393 void setHasBranchProtectedScope() {
394 HasBranchProtectedScope = true;
397 void setHasIndirectGoto() {
398 HasIndirectGoto = true;
401 void setHasDroppedStmt() {
402 HasDroppedStmt = true;
405 void setHasOMPDeclareReductionCombiner() {
406 HasOMPDeclareReductionCombiner = true;
409 void setHasFallthroughStmt() {
410 HasFallthroughStmt = true;
413 void setHasCXXTry(SourceLocation TryLoc) {
414 setHasBranchProtectedScope();
415 FirstCXXTryLoc = TryLoc;
418 void setHasSEHTry(SourceLocation TryLoc) {
419 setHasBranchProtectedScope();
420 FirstSEHTryLoc = TryLoc;
423 bool NeedsScopeChecking() const {
424 return !HasDroppedStmt &&
426 (HasBranchProtectedScope && HasBranchIntoScope));
429 bool isCoroutine() const { return !FirstCoroutineStmtLoc.isInvalid(); }
431 void setFirstCoroutineStmt(SourceLocation Loc, StringRef Keyword) {
432 assert(FirstCoroutineStmtLoc.isInvalid() &&
433 "first coroutine statement location already set");
434 FirstCoroutineStmtLoc = Loc;
435 FirstCoroutineStmtKind = llvm::StringSwitch<unsigned char>(Keyword)
436 .Case("co_return", 0)
438 .Case("co_yield", 2);
441 StringRef getFirstCoroutineStmtKeyword() const {
442 assert(FirstCoroutineStmtLoc.isValid()
443 && "no coroutine statement available");
444 switch (FirstCoroutineStmtKind) {
445 case 0: return "co_return";
446 case 1: return "co_await";
447 case 2: return "co_yield";
449 llvm_unreachable("FirstCoroutineStmtKind has an invalid value");
453 void setNeedsCoroutineSuspends(bool value = true) {
454 assert((!value || CoroutineSuspends.first == nullptr) &&
455 "we already have valid suspend points");
456 NeedsCoroutineSuspends = value;
459 bool hasInvalidCoroutineSuspends() const {
460 return !NeedsCoroutineSuspends && CoroutineSuspends.first == nullptr;
463 void setCoroutineSuspends(Stmt *Initial, Stmt *Final) {
464 assert(Initial && Final && "suspend points cannot be null");
465 assert(CoroutineSuspends.first == nullptr && "suspend points already set");
466 NeedsCoroutineSuspends = false;
467 CoroutineSuspends.first = Initial;
468 CoroutineSuspends.second = Final;
471 /// Clear out the information in this function scope, making it
472 /// suitable for reuse.
477 // There are three categories of capture: capturing 'this', capturing
478 // local variables, and C++1y initialized captures (which can have an
479 // arbitrary initializer, and don't really capture in the traditional
482 // There are three ways to capture a local variable:
483 // - capture by copy in the C++11 sense,
484 // - capture by reference in the C++11 sense, and
485 // - __block capture.
486 // Lambdas explicitly specify capture by copy or capture by reference.
487 // For blocks, __block capture applies to variables with that annotation,
488 // variables of reference type are captured by reference, and other
489 // variables are captured by copy.
491 Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_VLA
494 IsNestedCapture = 0x1,
498 /// The variable being captured (if we are not capturing 'this') and whether
499 /// this is a nested capture, and whether we are capturing 'this'
500 llvm::PointerIntPair<VarDecl*, 2> VarAndNestedAndThis;
502 /// Expression to initialize a field of the given type, and the kind of
503 /// capture (if this is a capture and not an init-capture). The expression
504 /// is only required if we are capturing ByVal and the variable's type has
505 /// a non-trivial copy constructor.
506 llvm::PointerIntPair<void *, 2, CaptureKind> InitExprAndCaptureKind;
508 /// The source location at which the first capture occurred.
511 /// The location of the ellipsis that expands a parameter pack.
512 SourceLocation EllipsisLoc;
514 /// The type as it was captured, which is in effect the type of the
515 /// non-static data member that would hold the capture.
516 QualType CaptureType;
518 /// Whether an explicit capture has been odr-used in the body of the
520 bool ODRUsed = false;
522 /// Whether an explicit capture has been non-odr-used in the body of
524 bool NonODRUsed = false;
527 Capture(VarDecl *Var, bool Block, bool ByRef, bool IsNested,
528 SourceLocation Loc, SourceLocation EllipsisLoc,
529 QualType CaptureType, Expr *Cpy)
530 : VarAndNestedAndThis(Var, IsNested ? IsNestedCapture : 0),
531 InitExprAndCaptureKind(
532 Cpy, !Var ? Cap_VLA : Block ? Cap_Block : ByRef ? Cap_ByRef
534 Loc(Loc), EllipsisLoc(EllipsisLoc), CaptureType(CaptureType) {}
536 enum IsThisCapture { ThisCapture };
537 Capture(IsThisCapture, bool IsNested, SourceLocation Loc,
538 QualType CaptureType, Expr *Cpy, const bool ByCopy)
539 : VarAndNestedAndThis(
540 nullptr, (IsThisCaptured | (IsNested ? IsNestedCapture : 0))),
541 InitExprAndCaptureKind(Cpy, ByCopy ? Cap_ByCopy : Cap_ByRef),
542 Loc(Loc), CaptureType(CaptureType) {}
544 bool isThisCapture() const {
545 return VarAndNestedAndThis.getInt() & IsThisCaptured;
548 bool isVariableCapture() const {
549 return !isThisCapture() && !isVLATypeCapture();
552 bool isCopyCapture() const {
553 return InitExprAndCaptureKind.getInt() == Cap_ByCopy;
556 bool isReferenceCapture() const {
557 return InitExprAndCaptureKind.getInt() == Cap_ByRef;
560 bool isBlockCapture() const {
561 return InitExprAndCaptureKind.getInt() == Cap_Block;
564 bool isVLATypeCapture() const {
565 return InitExprAndCaptureKind.getInt() == Cap_VLA;
568 bool isNested() const {
569 return VarAndNestedAndThis.getInt() & IsNestedCapture;
572 bool isODRUsed() const { return ODRUsed; }
573 bool isNonODRUsed() const { return NonODRUsed; }
574 void markUsed(bool IsODRUse) { (IsODRUse ? ODRUsed : NonODRUsed) = true; }
576 VarDecl *getVariable() const {
577 assert(isVariableCapture());
578 return VarAndNestedAndThis.getPointer();
581 /// Retrieve the location at which this variable was captured.
582 SourceLocation getLocation() const { return Loc; }
584 /// Retrieve the source location of the ellipsis, whose presence
585 /// indicates that the capture is a pack expansion.
586 SourceLocation getEllipsisLoc() const { return EllipsisLoc; }
588 /// Retrieve the capture type for this capture, which is effectively
589 /// the type of the non-static data member in the lambda/block structure
590 /// that would store this capture.
591 QualType getCaptureType() const {
592 assert(!isThisCapture());
596 Expr *getInitExpr() const {
597 assert(!isVLATypeCapture() && "no init expression for type capture");
598 return static_cast<Expr *>(InitExprAndCaptureKind.getPointer());
602 class CapturingScopeInfo : public FunctionScopeInfo {
604 CapturingScopeInfo(const CapturingScopeInfo&) = default;
607 enum ImplicitCaptureStyle {
608 ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block,
609 ImpCap_CapturedRegion
612 ImplicitCaptureStyle ImpCaptureStyle;
614 CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style)
615 : FunctionScopeInfo(Diag), ImpCaptureStyle(Style) {}
617 /// CaptureMap - A map of captured variables to (index+1) into Captures.
618 llvm::DenseMap<VarDecl*, unsigned> CaptureMap;
620 /// CXXThisCaptureIndex - The (index+1) of the capture of 'this';
621 /// zero if 'this' is not captured.
622 unsigned CXXThisCaptureIndex = 0;
624 /// Captures - The captures.
625 SmallVector<Capture, 4> Captures;
627 /// - Whether the target type of return statements in this context
628 /// is deduced (e.g. a lambda or block with omitted return type).
629 bool HasImplicitReturnType = false;
631 /// ReturnType - The target type of return statements in this context,
632 /// or null if unknown.
635 void addCapture(VarDecl *Var, bool isBlock, bool isByref, bool isNested,
636 SourceLocation Loc, SourceLocation EllipsisLoc,
637 QualType CaptureType, Expr *Cpy) {
638 Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc,
639 EllipsisLoc, CaptureType, Cpy));
640 CaptureMap[Var] = Captures.size();
643 void addVLATypeCapture(SourceLocation Loc, QualType CaptureType) {
644 Captures.push_back(Capture(/*Var*/ nullptr, /*isBlock*/ false,
645 /*isByref*/ false, /*isNested*/ false, Loc,
646 /*EllipsisLoc*/ SourceLocation(), CaptureType,
650 // Note, we do not need to add the type of 'this' since that is always
651 // retrievable from Sema::getCurrentThisType - and is also encoded within the
652 // type of the corresponding FieldDecl.
653 void addThisCapture(bool isNested, SourceLocation Loc,
654 Expr *Cpy, bool ByCopy);
656 /// Determine whether the C++ 'this' is captured.
657 bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; }
659 /// Retrieve the capture of C++ 'this', if it has been captured.
660 Capture &getCXXThisCapture() {
661 assert(isCXXThisCaptured() && "this has not been captured");
662 return Captures[CXXThisCaptureIndex - 1];
665 /// Determine whether the given variable has been captured.
666 bool isCaptured(VarDecl *Var) const {
667 return CaptureMap.count(Var);
670 /// Determine whether the given variable-array type has been captured.
671 bool isVLATypeCaptured(const VariableArrayType *VAT) const;
673 /// Retrieve the capture of the given variable, if it has been
674 /// captured already.
675 Capture &getCapture(VarDecl *Var) {
676 assert(isCaptured(Var) && "Variable has not been captured");
677 return Captures[CaptureMap[Var] - 1];
680 const Capture &getCapture(VarDecl *Var) const {
681 llvm::DenseMap<VarDecl*, unsigned>::const_iterator Known
682 = CaptureMap.find(Var);
683 assert(Known != CaptureMap.end() && "Variable has not been captured");
684 return Captures[Known->second - 1];
687 static bool classof(const FunctionScopeInfo *FSI) {
688 return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda
689 || FSI->Kind == SK_CapturedRegion;
693 /// Retains information about a block that is currently being parsed.
694 class BlockScopeInfo final : public CapturingScopeInfo {
698 /// TheScope - This is the scope for the block itself, which contains
702 /// BlockType - The function type of the block, if one was given.
703 /// Its return type may be BuiltinType::Dependent.
704 QualType FunctionType;
706 BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block)
707 : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block),
708 TheScope(BlockScope) {
712 ~BlockScopeInfo() override;
714 static bool classof(const FunctionScopeInfo *FSI) {
715 return FSI->Kind == SK_Block;
719 /// Retains information about a captured region.
720 class CapturedRegionScopeInfo final : public CapturingScopeInfo {
722 /// The CapturedDecl for this statement.
723 CapturedDecl *TheCapturedDecl;
725 /// The captured record type.
726 RecordDecl *TheRecordDecl;
728 /// This is the enclosing scope of the captured region.
731 /// The implicit parameter for the captured variables.
732 ImplicitParamDecl *ContextParam;
734 /// The kind of captured region.
735 unsigned short CapRegionKind;
737 unsigned short OpenMPLevel;
739 CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD,
740 RecordDecl *RD, ImplicitParamDecl *Context,
741 CapturedRegionKind K, unsigned OpenMPLevel)
742 : CapturingScopeInfo(Diag, ImpCap_CapturedRegion),
743 TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S),
744 ContextParam(Context), CapRegionKind(K), OpenMPLevel(OpenMPLevel) {
745 Kind = SK_CapturedRegion;
748 ~CapturedRegionScopeInfo() override;
750 /// A descriptive name for the kind of captured region this is.
751 StringRef getRegionName() const {
752 switch (CapRegionKind) {
754 return "default captured statement";
755 case CR_ObjCAtFinally:
756 return "Objective-C @finally statement";
758 return "OpenMP region";
760 llvm_unreachable("Invalid captured region kind!");
763 static bool classof(const FunctionScopeInfo *FSI) {
764 return FSI->Kind == SK_CapturedRegion;
768 class LambdaScopeInfo final : public CapturingScopeInfo {
770 /// The class that describes the lambda.
771 CXXRecordDecl *Lambda = nullptr;
773 /// The lambda's compiler-generated \c operator().
774 CXXMethodDecl *CallOperator = nullptr;
776 /// Source range covering the lambda introducer [...].
777 SourceRange IntroducerRange;
779 /// Source location of the '&' or '=' specifying the default capture
781 SourceLocation CaptureDefaultLoc;
783 /// The number of captures in the \c Captures list that are
784 /// explicit captures.
785 unsigned NumExplicitCaptures = 0;
787 /// Whether this is a mutable lambda.
788 bool Mutable = false;
790 /// Whether the (empty) parameter list is explicit.
791 bool ExplicitParams = false;
793 /// Whether any of the capture expressions requires cleanups.
796 /// Whether the lambda contains an unexpanded parameter pack.
797 bool ContainsUnexpandedParameterPack = false;
799 /// If this is a generic lambda, use this as the depth of
800 /// each 'auto' parameter, during initial AST construction.
801 unsigned AutoTemplateParameterDepth = 0;
803 /// Store the list of the auto parameters for a generic lambda.
804 /// If this is a generic lambda, store the list of the auto
805 /// parameters converted into TemplateTypeParmDecls into a vector
806 /// that can be used to construct the generic lambda's template
807 /// parameter list, during initial AST construction.
808 SmallVector<TemplateTypeParmDecl*, 4> AutoTemplateParams;
810 /// If this is a generic lambda, and the template parameter
811 /// list has been created (from the AutoTemplateParams) then
812 /// store a reference to it (cache it to avoid reconstructing it).
813 TemplateParameterList *GLTemplateParameterList = nullptr;
815 /// Contains all variable-referring-expressions (i.e. DeclRefExprs
816 /// or MemberExprs) that refer to local variables in a generic lambda
817 /// or a lambda in a potentially-evaluated-if-used context.
819 /// Potentially capturable variables of a nested lambda that might need
820 /// to be captured by the lambda are housed here.
821 /// This is specifically useful for generic lambdas or
822 /// lambdas within a potentially evaluated-if-used context.
823 /// If an enclosing variable is named in an expression of a lambda nested
824 /// within a generic lambda, we don't always know know whether the variable
825 /// will truly be odr-used (i.e. need to be captured) by that nested lambda,
826 /// until its instantiation. But we still need to capture it in the
827 /// enclosing lambda if all intervening lambdas can capture the variable.
828 llvm::SmallVector<Expr*, 4> PotentiallyCapturingExprs;
830 /// Contains all variable-referring-expressions that refer
831 /// to local variables that are usable as constant expressions and
832 /// do not involve an odr-use (they may still need to be captured
833 /// if the enclosing full-expression is instantiation dependent).
834 llvm::SmallSet<Expr *, 8> NonODRUsedCapturingExprs;
836 /// A map of explicit capture indices to their introducer source ranges.
837 llvm::DenseMap<unsigned, SourceRange> ExplicitCaptureRanges;
839 /// Contains all of the variables defined in this lambda that shadow variables
840 /// that were defined in parent contexts. Used to avoid warnings when the
841 /// shadowed variables are uncaptured by this lambda.
842 struct ShadowedOuterDecl {
844 const VarDecl *ShadowedDecl;
846 llvm::SmallVector<ShadowedOuterDecl, 4> ShadowingDecls;
848 SourceLocation PotentialThisCaptureLocation;
850 LambdaScopeInfo(DiagnosticsEngine &Diag)
851 : CapturingScopeInfo(Diag, ImpCap_None) {
855 /// Note when all explicit captures have been added.
856 void finishedExplicitCaptures() {
857 NumExplicitCaptures = Captures.size();
860 static bool classof(const FunctionScopeInfo *FSI) {
861 return FSI->Kind == SK_Lambda;
864 /// Is this scope known to be for a generic lambda? (This will be false until
865 /// we parse the first 'auto'-typed parameter.
866 bool isGenericLambda() const {
867 return !AutoTemplateParams.empty() || GLTemplateParameterList;
870 /// Add a variable that might potentially be captured by the
871 /// lambda and therefore the enclosing lambdas.
873 /// This is also used by enclosing lambda's to speculatively capture
874 /// variables that nested lambda's - depending on their enclosing
875 /// specialization - might need to capture.
877 /// void f(int, int); <-- don't capture
878 /// void f(const int&, double); <-- capture
880 /// const int x = 10;
881 /// auto L = [=](auto a) { // capture 'x'
882 /// return [=](auto b) {
883 /// f(x, a); // we may or may not need to capture 'x'
887 void addPotentialCapture(Expr *VarExpr) {
888 assert(isa<DeclRefExpr>(VarExpr) || isa<MemberExpr>(VarExpr));
889 PotentiallyCapturingExprs.push_back(VarExpr);
892 void addPotentialThisCapture(SourceLocation Loc) {
893 PotentialThisCaptureLocation = Loc;
896 bool hasPotentialThisCapture() const {
897 return PotentialThisCaptureLocation.isValid();
900 /// Mark a variable's reference in a lambda as non-odr using.
902 /// For generic lambdas, if a variable is named in a potentially evaluated
903 /// expression, where the enclosing full expression is dependent then we
904 /// must capture the variable (given a default capture).
905 /// This is accomplished by recording all references to variables
906 /// (DeclRefExprs or MemberExprs) within said nested lambda in its array of
907 /// PotentialCaptures. All such variables have to be captured by that lambda,
908 /// except for as described below.
909 /// If that variable is usable as a constant expression and is named in a
910 /// manner that does not involve its odr-use (e.g. undergoes
911 /// lvalue-to-rvalue conversion, or discarded) record that it is so. Upon the
912 /// act of analyzing the enclosing full expression (ActOnFinishFullExpr)
913 /// if we can determine that the full expression is not instantiation-
914 /// dependent, then we can entirely avoid its capture.
920 /// Interestingly, this strategy would involve a capture of n, even though
921 /// it's obviously not odr-used here, because the full-expression is
922 /// instantiation-dependent. It could be useful to avoid capturing such
923 /// variables, even when they are referred to in an instantiation-dependent
924 /// expression, if we can unambiguously determine that they shall never be
925 /// odr-used. This would involve removal of the variable-referring-expression
926 /// from the array of PotentialCaptures during the lvalue-to-rvalue
927 /// conversions. But per the working draft N3797, (post-chicago 2013) we must
928 /// capture such variables.
929 /// Before anyone is tempted to implement a strategy for not-capturing 'n',
930 /// consider the insightful warning in:
931 /// /cfe-commits/Week-of-Mon-20131104/092596.html
932 /// "The problem is that the set of captures for a lambda is part of the ABI
933 /// (since lambda layout can be made visible through inline functions and the
934 /// like), and there are no guarantees as to which cases we'll manage to build
935 /// an lvalue-to-rvalue conversion in, when parsing a template -- some
936 /// seemingly harmless change elsewhere in Sema could cause us to start or stop
937 /// building such a node. So we need a rule that anyone can implement and get
938 /// exactly the same result".
939 void markVariableExprAsNonODRUsed(Expr *CapturingVarExpr) {
940 assert(isa<DeclRefExpr>(CapturingVarExpr)
941 || isa<MemberExpr>(CapturingVarExpr));
942 NonODRUsedCapturingExprs.insert(CapturingVarExpr);
944 bool isVariableExprMarkedAsNonODRUsed(Expr *CapturingVarExpr) const {
945 assert(isa<DeclRefExpr>(CapturingVarExpr)
946 || isa<MemberExpr>(CapturingVarExpr));
947 return NonODRUsedCapturingExprs.count(CapturingVarExpr);
949 void removePotentialCapture(Expr *E) {
950 PotentiallyCapturingExprs.erase(
951 std::remove(PotentiallyCapturingExprs.begin(),
952 PotentiallyCapturingExprs.end(), E),
953 PotentiallyCapturingExprs.end());
955 void clearPotentialCaptures() {
956 PotentiallyCapturingExprs.clear();
957 PotentialThisCaptureLocation = SourceLocation();
959 unsigned getNumPotentialVariableCaptures() const {
960 return PotentiallyCapturingExprs.size();
963 bool hasPotentialCaptures() const {
964 return getNumPotentialVariableCaptures() ||
965 PotentialThisCaptureLocation.isValid();
968 // When passed the index, returns the VarDecl and Expr associated
970 void getPotentialVariableCapture(unsigned Idx, VarDecl *&VD, Expr *&E) const;
973 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy()
974 : Base(nullptr, false) {}
976 FunctionScopeInfo::WeakObjectProfileTy
977 FunctionScopeInfo::WeakObjectProfileTy::getSentinel() {
978 FunctionScopeInfo::WeakObjectProfileTy Result;
979 Result.Base.setInt(true);
983 template <typename ExprT>
984 void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) {
986 WeakUseVector &Uses = WeakObjectUses[WeakObjectProfileTy(E)];
987 Uses.push_back(WeakUseTy(E, IsRead));
991 CapturingScopeInfo::addThisCapture(bool isNested, SourceLocation Loc,
994 Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, QualType(),
996 CXXThisCaptureIndex = Captures.size();
1001 } // namespace clang
1003 #endif // LLVM_CLANG_SEMA_SCOPEINFO_H