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/PartialDiagnostic.h"
22 #include "clang/Sema/CleanupInfo.h"
23 #include "clang/Sema/Ownership.h"
24 #include "llvm/ADT/DenseMap.h"
25 #include "llvm/ADT/SmallSet.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/ADT/StringSwitch.h"
37 class ObjCPropertyDecl;
39 class ImplicitParamDecl;
44 class TemplateTypeParmDecl;
45 class TemplateParameterList;
47 class ObjCIvarRefExpr;
48 class ObjCPropertyRefExpr;
49 class ObjCMessageExpr;
53 /// \brief Contains information about the compound statement currently being
55 class CompoundScopeInfo {
58 : HasEmptyLoopBodies(false) { }
60 /// \brief Whether this compound stamement contains `for' or `while' loops
61 /// with empty bodies.
62 bool HasEmptyLoopBodies;
64 void setHasEmptyLoopBodies() {
65 HasEmptyLoopBodies = true;
69 class PossiblyUnreachableDiag {
75 PossiblyUnreachableDiag(const PartialDiagnostic &PD, SourceLocation Loc,
77 : PD(PD), Loc(Loc), stmt(stmt) {}
80 /// \brief Retains information about a function, method, or block that is
81 /// currently being parsed.
82 class FunctionScopeInfo {
92 /// \brief What kind of scope we are describing.
96 /// \brief Whether this function contains a VLA, \@try, try, C++
97 /// initializer, or anything else that can't be jumped past.
98 bool HasBranchProtectedScope : 1;
100 /// \brief Whether this function contains any switches or direct gotos.
101 bool HasBranchIntoScope : 1;
103 /// \brief Whether this function contains any indirect gotos.
104 bool HasIndirectGoto : 1;
106 /// \brief Whether a statement was dropped because it was invalid.
107 bool HasDroppedStmt : 1;
109 /// \brief True if current scope is for OpenMP declare reduction combiner.
110 bool HasOMPDeclareReductionCombiner : 1;
112 /// \brief Whether there is a fallthrough statement in this function.
113 bool HasFallthroughStmt : 1;
115 /// \brief Whether we make reference to a declaration that could be
117 bool HasPotentialAvailabilityViolations : 1;
119 /// A flag that is set when parsing a method that must call super's
120 /// implementation, such as \c -dealloc, \c -finalize, or any method marked
121 /// with \c __attribute__((objc_requires_super)).
122 bool ObjCShouldCallSuper : 1;
124 /// True when this is a method marked as a designated initializer.
125 bool ObjCIsDesignatedInit : 1;
126 /// This starts true for a method marked as designated initializer and will
127 /// be set to false if there is an invocation to a designated initializer of
129 bool ObjCWarnForNoDesignatedInitChain : 1;
131 /// True when this is an initializer method not marked as a designated
132 /// initializer within a class that has at least one initializer marked as a
133 /// designated initializer.
134 bool ObjCIsSecondaryInit : 1;
135 /// This starts true for a secondary initializer method and will be set to
136 /// false if there is an invocation of an initializer on 'self'.
137 bool ObjCWarnForNoInitDelegation : 1;
139 /// \brief True only when this function has not already built, or attempted
140 /// to build, the initial and final coroutine suspend points
141 bool NeedsCoroutineSuspends : 1;
143 /// \brief An enumeration represeting the kind of the first coroutine statement
144 /// in the function. One of co_return, co_await, or co_yield.
145 unsigned char FirstCoroutineStmtKind : 2;
147 /// First coroutine statement in the current function.
148 /// (ex co_return, co_await, co_yield)
149 SourceLocation FirstCoroutineStmtLoc;
151 /// First 'return' statement in the current function.
152 SourceLocation FirstReturnLoc;
154 /// First C++ 'try' statement in the current function.
155 SourceLocation FirstCXXTryLoc;
157 /// First SEH '__try' statement in the current function.
158 SourceLocation FirstSEHTryLoc;
160 /// \brief Used to determine if errors occurred in this function or block.
161 DiagnosticErrorTrap ErrorTrap;
163 /// SwitchStack - This is the current set of active switch statements in the
165 SmallVector<SwitchStmt*, 8> SwitchStack;
167 /// \brief The list of return statements that occur within the function or
168 /// block, if there is any chance of applying the named return value
169 /// optimization, or if we need to infer a return type.
170 SmallVector<ReturnStmt*, 4> Returns;
172 /// \brief The promise object for this coroutine, if any.
173 VarDecl *CoroutinePromise = nullptr;
175 /// \brief The initial and final coroutine suspend points.
176 std::pair<Stmt *, Stmt *> CoroutineSuspends;
178 /// \brief The stack of currently active compound stamement scopes in the
180 SmallVector<CompoundScopeInfo, 4> CompoundScopes;
182 /// \brief A list of PartialDiagnostics created but delayed within the
183 /// current function scope. These diagnostics are vetted for reachability
184 /// prior to being emitted.
185 SmallVector<PossiblyUnreachableDiag, 4> PossiblyUnreachableDiags;
187 /// \brief A list of parameters which have the nonnull attribute and are
188 /// modified in the function.
189 llvm::SmallPtrSet<const ParmVarDecl*, 8> ModifiedNonNullParams;
192 /// Represents a simple identification of a weak object.
194 /// Part of the implementation of -Wrepeated-use-of-weak.
196 /// This is used to determine if two weak accesses refer to the same object.
197 /// Here are some examples of how various accesses are "profiled":
199 /// Access Expression | "Base" Decl | "Property" Decl
200 /// :---------------: | :-----------------: | :------------------------------:
201 /// self.property | self (VarDecl) | property (ObjCPropertyDecl)
202 /// self.implicitProp | self (VarDecl) | -implicitProp (ObjCMethodDecl)
203 /// self->ivar.prop | ivar (ObjCIvarDecl) | prop (ObjCPropertyDecl)
204 /// cxxObj.obj.prop | obj (FieldDecl) | prop (ObjCPropertyDecl)
205 /// [self foo].prop | 0 (unknown) | prop (ObjCPropertyDecl)
206 /// self.prop1.prop2 | prop1 (ObjCPropertyDecl) | prop2 (ObjCPropertyDecl)
207 /// MyClass.prop | MyClass (ObjCInterfaceDecl) | -prop (ObjCMethodDecl)
208 /// MyClass.foo.prop | +foo (ObjCMethodDecl) | -prop (ObjCPropertyDecl)
209 /// weakVar | 0 (known) | weakVar (VarDecl)
210 /// self->weakIvar | self (VarDecl) | weakIvar (ObjCIvarDecl)
212 /// Objects are identified with only two Decls to make it reasonably fast to
214 class WeakObjectProfileTy {
215 /// The base object decl, as described in the class documentation.
217 /// The extra flag is "true" if the Base and Property are enough to uniquely
218 /// identify the object in memory.
220 /// \sa isExactProfile()
221 typedef llvm::PointerIntPair<const NamedDecl *, 1, bool> BaseInfoTy;
224 /// The "property" decl, as described in the class documentation.
226 /// Note that this may not actually be an ObjCPropertyDecl, e.g. in the
227 /// case of "implicit" properties (regular methods accessed via dot syntax).
228 const NamedDecl *Property;
230 /// Used to find the proper base profile for a given base expression.
231 static BaseInfoTy getBaseInfo(const Expr *BaseE);
233 inline WeakObjectProfileTy();
234 static inline WeakObjectProfileTy getSentinel();
237 WeakObjectProfileTy(const ObjCPropertyRefExpr *RE);
238 WeakObjectProfileTy(const Expr *Base, const ObjCPropertyDecl *Property);
239 WeakObjectProfileTy(const DeclRefExpr *RE);
240 WeakObjectProfileTy(const ObjCIvarRefExpr *RE);
242 const NamedDecl *getBase() const { return Base.getPointer(); }
243 const NamedDecl *getProperty() const { return Property; }
245 /// Returns true if the object base specifies a known object in memory,
246 /// rather than, say, an instance variable or property of another object.
248 /// Note that this ignores the effects of aliasing; that is, \c foo.bar is
249 /// considered an exact profile if \c foo is a local variable, even if
250 /// another variable \c foo2 refers to the same object as \c foo.
252 /// For increased precision, accesses with base variables that are
253 /// properties or ivars of 'self' (e.g. self.prop1.prop2) are considered to
254 /// be exact, though this is not true for arbitrary variables
255 /// (foo.prop1.prop2).
256 bool isExactProfile() const {
257 return Base.getInt();
260 bool operator==(const WeakObjectProfileTy &Other) const {
261 return Base == Other.Base && Property == Other.Property;
264 // For use in DenseMap.
265 // We can't specialize the usual llvm::DenseMapInfo at the end of the file
266 // because by that point the DenseMap in FunctionScopeInfo has already been
270 static inline WeakObjectProfileTy getEmptyKey() {
271 return WeakObjectProfileTy();
273 static inline WeakObjectProfileTy getTombstoneKey() {
274 return WeakObjectProfileTy::getSentinel();
277 static unsigned getHashValue(const WeakObjectProfileTy &Val) {
278 typedef std::pair<BaseInfoTy, const NamedDecl *> Pair;
279 return llvm::DenseMapInfo<Pair>::getHashValue(Pair(Val.Base,
283 static bool isEqual(const WeakObjectProfileTy &LHS,
284 const WeakObjectProfileTy &RHS) {
290 /// Represents a single use of a weak object.
292 /// Stores both the expression and whether the access is potentially unsafe
293 /// (i.e. it could potentially be warned about).
295 /// Part of the implementation of -Wrepeated-use-of-weak.
297 llvm::PointerIntPair<const Expr *, 1, bool> Rep;
299 WeakUseTy(const Expr *Use, bool IsRead) : Rep(Use, IsRead) {}
301 const Expr *getUseExpr() const { return Rep.getPointer(); }
302 bool isUnsafe() const { return Rep.getInt(); }
303 void markSafe() { Rep.setInt(false); }
305 bool operator==(const WeakUseTy &Other) const {
306 return Rep == Other.Rep;
310 /// Used to collect uses of a particular weak object in a function body.
312 /// Part of the implementation of -Wrepeated-use-of-weak.
313 typedef SmallVector<WeakUseTy, 4> WeakUseVector;
315 /// Used to collect all uses of weak objects in a function body.
317 /// Part of the implementation of -Wrepeated-use-of-weak.
318 typedef llvm::SmallDenseMap<WeakObjectProfileTy, WeakUseVector, 8,
319 WeakObjectProfileTy::DenseMapInfo>
323 /// Used to collect all uses of weak objects in this function body.
325 /// Part of the implementation of -Wrepeated-use-of-weak.
326 WeakObjectUseMap WeakObjectUses;
329 FunctionScopeInfo(const FunctionScopeInfo&) = default;
332 /// Record that a weak object was accessed.
334 /// Part of the implementation of -Wrepeated-use-of-weak.
335 template <typename ExprT>
336 inline void recordUseOfWeak(const ExprT *E, bool IsRead = true);
338 void recordUseOfWeak(const ObjCMessageExpr *Msg,
339 const ObjCPropertyDecl *Prop);
341 /// Record that a given expression is a "safe" access of a weak object (e.g.
342 /// assigning it to a strong variable.)
344 /// Part of the implementation of -Wrepeated-use-of-weak.
345 void markSafeWeakUse(const Expr *E);
347 const WeakObjectUseMap &getWeakObjectUses() const {
348 return WeakObjectUses;
351 void setHasBranchIntoScope() {
352 HasBranchIntoScope = true;
355 void setHasBranchProtectedScope() {
356 HasBranchProtectedScope = true;
359 void setHasIndirectGoto() {
360 HasIndirectGoto = true;
363 void setHasDroppedStmt() {
364 HasDroppedStmt = true;
367 void setHasOMPDeclareReductionCombiner() {
368 HasOMPDeclareReductionCombiner = true;
371 void setHasFallthroughStmt() {
372 HasFallthroughStmt = true;
375 void setHasCXXTry(SourceLocation TryLoc) {
376 setHasBranchProtectedScope();
377 FirstCXXTryLoc = TryLoc;
380 void setHasSEHTry(SourceLocation TryLoc) {
381 setHasBranchProtectedScope();
382 FirstSEHTryLoc = TryLoc;
385 bool NeedsScopeChecking() const {
386 return !HasDroppedStmt &&
388 (HasBranchProtectedScope && HasBranchIntoScope));
391 bool isCoroutine() const { return !FirstCoroutineStmtLoc.isInvalid(); }
393 void setFirstCoroutineStmt(SourceLocation Loc, StringRef Keyword) {
394 assert(FirstCoroutineStmtLoc.isInvalid() &&
395 "first coroutine statement location already set");
396 FirstCoroutineStmtLoc = Loc;
397 FirstCoroutineStmtKind = llvm::StringSwitch<unsigned char>(Keyword)
398 .Case("co_return", 0)
400 .Case("co_yield", 2);
403 StringRef getFirstCoroutineStmtKeyword() const {
404 assert(FirstCoroutineStmtLoc.isValid()
405 && "no coroutine statement available");
406 switch (FirstCoroutineStmtKind) {
407 case 0: return "co_return";
408 case 1: return "co_await";
409 case 2: return "co_yield";
411 llvm_unreachable("FirstCoroutineStmtKind has an invalid value");
415 void setNeedsCoroutineSuspends(bool value = true) {
416 assert((!value || CoroutineSuspends.first == nullptr) &&
417 "we already have valid suspend points");
418 NeedsCoroutineSuspends = value;
421 bool hasInvalidCoroutineSuspends() const {
422 return !NeedsCoroutineSuspends && CoroutineSuspends.first == nullptr;
425 void setCoroutineSuspends(Stmt *Initial, Stmt *Final) {
426 assert(Initial && Final && "suspend points cannot be null");
427 assert(CoroutineSuspends.first == nullptr && "suspend points already set");
428 NeedsCoroutineSuspends = false;
429 CoroutineSuspends.first = Initial;
430 CoroutineSuspends.second = Final;
433 FunctionScopeInfo(DiagnosticsEngine &Diag)
435 HasBranchProtectedScope(false),
436 HasBranchIntoScope(false),
437 HasIndirectGoto(false),
438 HasDroppedStmt(false),
439 HasOMPDeclareReductionCombiner(false),
440 HasFallthroughStmt(false),
441 HasPotentialAvailabilityViolations(false),
442 ObjCShouldCallSuper(false),
443 ObjCIsDesignatedInit(false),
444 ObjCWarnForNoDesignatedInitChain(false),
445 ObjCIsSecondaryInit(false),
446 ObjCWarnForNoInitDelegation(false),
447 NeedsCoroutineSuspends(true),
450 virtual ~FunctionScopeInfo();
452 /// \brief Clear out the information in this function scope, making it
453 /// suitable for reuse.
457 class CapturingScopeInfo : public FunctionScopeInfo {
459 CapturingScopeInfo(const CapturingScopeInfo&) = default;
462 enum ImplicitCaptureStyle {
463 ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block,
464 ImpCap_CapturedRegion
467 ImplicitCaptureStyle ImpCaptureStyle;
470 // There are three categories of capture: capturing 'this', capturing
471 // local variables, and C++1y initialized captures (which can have an
472 // arbitrary initializer, and don't really capture in the traditional
475 // There are three ways to capture a local variable:
476 // - capture by copy in the C++11 sense,
477 // - capture by reference in the C++11 sense, and
478 // - __block capture.
479 // Lambdas explicitly specify capture by copy or capture by reference.
480 // For blocks, __block capture applies to variables with that annotation,
481 // variables of reference type are captured by reference, and other
482 // variables are captured by copy.
484 Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_VLA
487 IsNestedCapture = 0x1,
490 /// The variable being captured (if we are not capturing 'this') and whether
491 /// this is a nested capture, and whether we are capturing 'this'
492 llvm::PointerIntPair<VarDecl*, 2> VarAndNestedAndThis;
493 /// Expression to initialize a field of the given type, and the kind of
494 /// capture (if this is a capture and not an init-capture). The expression
495 /// is only required if we are capturing ByVal and the variable's type has
496 /// a non-trivial copy constructor.
497 llvm::PointerIntPair<void *, 2, CaptureKind> InitExprAndCaptureKind;
499 /// \brief The source location at which the first capture occurred.
502 /// \brief The location of the ellipsis that expands a parameter pack.
503 SourceLocation EllipsisLoc;
505 /// \brief The type as it was captured, which is in effect the type of the
506 /// non-static data member that would hold the capture.
507 QualType CaptureType;
509 /// \brief Whether an explicit capture has been odr-used in the body of the
513 /// \brief Whether an explicit capture has been non-odr-used in the body of
518 Capture(VarDecl *Var, bool Block, bool ByRef, bool IsNested,
519 SourceLocation Loc, SourceLocation EllipsisLoc,
520 QualType CaptureType, Expr *Cpy)
521 : VarAndNestedAndThis(Var, IsNested ? IsNestedCapture : 0),
522 InitExprAndCaptureKind(
523 Cpy, !Var ? Cap_VLA : Block ? Cap_Block : ByRef ? Cap_ByRef
525 Loc(Loc), EllipsisLoc(EllipsisLoc), CaptureType(CaptureType),
526 ODRUsed(false), NonODRUsed(false) {}
528 enum IsThisCapture { ThisCapture };
529 Capture(IsThisCapture, bool IsNested, SourceLocation Loc,
530 QualType CaptureType, Expr *Cpy, const bool ByCopy)
531 : VarAndNestedAndThis(
532 nullptr, (IsThisCaptured | (IsNested ? IsNestedCapture : 0))),
533 InitExprAndCaptureKind(Cpy, ByCopy ? Cap_ByCopy : Cap_ByRef),
534 Loc(Loc), EllipsisLoc(), CaptureType(CaptureType), ODRUsed(false),
537 bool isThisCapture() const {
538 return VarAndNestedAndThis.getInt() & IsThisCaptured;
540 bool isVariableCapture() const {
541 return !isThisCapture() && !isVLATypeCapture();
543 bool isCopyCapture() const {
544 return InitExprAndCaptureKind.getInt() == Cap_ByCopy;
546 bool isReferenceCapture() const {
547 return InitExprAndCaptureKind.getInt() == Cap_ByRef;
549 bool isBlockCapture() const {
550 return InitExprAndCaptureKind.getInt() == Cap_Block;
552 bool isVLATypeCapture() const {
553 return InitExprAndCaptureKind.getInt() == Cap_VLA;
555 bool isNested() const {
556 return VarAndNestedAndThis.getInt() & IsNestedCapture;
558 bool isODRUsed() const { return ODRUsed; }
559 bool isNonODRUsed() const { return NonODRUsed; }
560 void markUsed(bool IsODRUse) { (IsODRUse ? ODRUsed : NonODRUsed) = true; }
562 VarDecl *getVariable() const {
563 assert(isVariableCapture());
564 return VarAndNestedAndThis.getPointer();
567 /// \brief Retrieve the location at which this variable was captured.
568 SourceLocation getLocation() const { return Loc; }
570 /// \brief Retrieve the source location of the ellipsis, whose presence
571 /// indicates that the capture is a pack expansion.
572 SourceLocation getEllipsisLoc() const { return EllipsisLoc; }
574 /// \brief Retrieve the capture type for this capture, which is effectively
575 /// the type of the non-static data member in the lambda/block structure
576 /// that would store this capture.
577 QualType getCaptureType() const {
578 assert(!isThisCapture());
582 Expr *getInitExpr() const {
583 assert(!isVLATypeCapture() && "no init expression for type capture");
584 return static_cast<Expr *>(InitExprAndCaptureKind.getPointer());
588 CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style)
589 : FunctionScopeInfo(Diag), ImpCaptureStyle(Style), CXXThisCaptureIndex(0),
590 HasImplicitReturnType(false)
593 /// CaptureMap - A map of captured variables to (index+1) into Captures.
594 llvm::DenseMap<VarDecl*, unsigned> CaptureMap;
596 /// CXXThisCaptureIndex - The (index+1) of the capture of 'this';
597 /// zero if 'this' is not captured.
598 unsigned CXXThisCaptureIndex;
600 /// Captures - The captures.
601 SmallVector<Capture, 4> Captures;
603 /// \brief - Whether the target type of return statements in this context
604 /// is deduced (e.g. a lambda or block with omitted return type).
605 bool HasImplicitReturnType;
607 /// ReturnType - The target type of return statements in this context,
608 /// or null if unknown.
611 void addCapture(VarDecl *Var, bool isBlock, bool isByref, bool isNested,
612 SourceLocation Loc, SourceLocation EllipsisLoc,
613 QualType CaptureType, Expr *Cpy) {
614 Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc,
615 EllipsisLoc, CaptureType, Cpy));
616 CaptureMap[Var] = Captures.size();
619 void addVLATypeCapture(SourceLocation Loc, QualType CaptureType) {
620 Captures.push_back(Capture(/*Var*/ nullptr, /*isBlock*/ false,
621 /*isByref*/ false, /*isNested*/ false, Loc,
622 /*EllipsisLoc*/ SourceLocation(), CaptureType,
626 // Note, we do not need to add the type of 'this' since that is always
627 // retrievable from Sema::getCurrentThisType - and is also encoded within the
628 // type of the corresponding FieldDecl.
629 void addThisCapture(bool isNested, SourceLocation Loc,
630 Expr *Cpy, bool ByCopy);
632 /// \brief Determine whether the C++ 'this' is captured.
633 bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; }
635 /// \brief Retrieve the capture of C++ 'this', if it has been captured.
636 Capture &getCXXThisCapture() {
637 assert(isCXXThisCaptured() && "this has not been captured");
638 return Captures[CXXThisCaptureIndex - 1];
641 /// \brief Determine whether the given variable has been captured.
642 bool isCaptured(VarDecl *Var) const {
643 return CaptureMap.count(Var);
646 /// \brief Determine whether the given variable-array type has been captured.
647 bool isVLATypeCaptured(const VariableArrayType *VAT) const;
649 /// \brief Retrieve the capture of the given variable, if it has been
650 /// captured already.
651 Capture &getCapture(VarDecl *Var) {
652 assert(isCaptured(Var) && "Variable has not been captured");
653 return Captures[CaptureMap[Var] - 1];
656 const Capture &getCapture(VarDecl *Var) const {
657 llvm::DenseMap<VarDecl*, unsigned>::const_iterator Known
658 = CaptureMap.find(Var);
659 assert(Known != CaptureMap.end() && "Variable has not been captured");
660 return Captures[Known->second - 1];
663 static bool classof(const FunctionScopeInfo *FSI) {
664 return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda
665 || FSI->Kind == SK_CapturedRegion;
669 /// \brief Retains information about a block that is currently being parsed.
670 class BlockScopeInfo final : public CapturingScopeInfo {
674 /// TheScope - This is the scope for the block itself, which contains
678 /// BlockType - The function type of the block, if one was given.
679 /// Its return type may be BuiltinType::Dependent.
680 QualType FunctionType;
682 BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block)
683 : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block),
689 ~BlockScopeInfo() override;
691 static bool classof(const FunctionScopeInfo *FSI) {
692 return FSI->Kind == SK_Block;
696 /// \brief Retains information about a captured region.
697 class CapturedRegionScopeInfo final : public CapturingScopeInfo {
699 /// \brief The CapturedDecl for this statement.
700 CapturedDecl *TheCapturedDecl;
701 /// \brief The captured record type.
702 RecordDecl *TheRecordDecl;
703 /// \brief This is the enclosing scope of the captured region.
705 /// \brief The implicit parameter for the captured variables.
706 ImplicitParamDecl *ContextParam;
707 /// \brief The kind of captured region.
708 unsigned short CapRegionKind;
709 unsigned short OpenMPLevel;
711 CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD,
712 RecordDecl *RD, ImplicitParamDecl *Context,
713 CapturedRegionKind K, unsigned OpenMPLevel)
714 : CapturingScopeInfo(Diag, ImpCap_CapturedRegion),
715 TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S),
716 ContextParam(Context), CapRegionKind(K), OpenMPLevel(OpenMPLevel)
718 Kind = SK_CapturedRegion;
721 ~CapturedRegionScopeInfo() override;
723 /// \brief A descriptive name for the kind of captured region this is.
724 StringRef getRegionName() const {
725 switch (CapRegionKind) {
727 return "default captured statement";
729 return "OpenMP region";
731 llvm_unreachable("Invalid captured region kind!");
734 static bool classof(const FunctionScopeInfo *FSI) {
735 return FSI->Kind == SK_CapturedRegion;
739 class LambdaScopeInfo final : public CapturingScopeInfo {
741 /// \brief The class that describes the lambda.
742 CXXRecordDecl *Lambda;
744 /// \brief The lambda's compiler-generated \c operator().
745 CXXMethodDecl *CallOperator;
747 /// \brief Source range covering the lambda introducer [...].
748 SourceRange IntroducerRange;
750 /// \brief Source location of the '&' or '=' specifying the default capture
752 SourceLocation CaptureDefaultLoc;
754 /// \brief The number of captures in the \c Captures list that are
755 /// explicit captures.
756 unsigned NumExplicitCaptures;
758 /// \brief Whether this is a mutable lambda.
761 /// \brief Whether the (empty) parameter list is explicit.
764 /// \brief Whether any of the capture expressions requires cleanups.
767 /// \brief Whether the lambda contains an unexpanded parameter pack.
768 bool ContainsUnexpandedParameterPack;
770 /// \brief If this is a generic lambda, use this as the depth of
771 /// each 'auto' parameter, during initial AST construction.
772 unsigned AutoTemplateParameterDepth;
774 /// \brief Store the list of the auto parameters for a generic lambda.
775 /// If this is a generic lambda, store the list of the auto
776 /// parameters converted into TemplateTypeParmDecls into a vector
777 /// that can be used to construct the generic lambda's template
778 /// parameter list, during initial AST construction.
779 SmallVector<TemplateTypeParmDecl*, 4> AutoTemplateParams;
781 /// If this is a generic lambda, and the template parameter
782 /// list has been created (from the AutoTemplateParams) then
783 /// store a reference to it (cache it to avoid reconstructing it).
784 TemplateParameterList *GLTemplateParameterList;
786 /// \brief Contains all variable-referring-expressions (i.e. DeclRefExprs
787 /// or MemberExprs) that refer to local variables in a generic lambda
788 /// or a lambda in a potentially-evaluated-if-used context.
790 /// Potentially capturable variables of a nested lambda that might need
791 /// to be captured by the lambda are housed here.
792 /// This is specifically useful for generic lambdas or
793 /// lambdas within a a potentially evaluated-if-used context.
794 /// If an enclosing variable is named in an expression of a lambda nested
795 /// within a generic lambda, we don't always know know whether the variable
796 /// will truly be odr-used (i.e. need to be captured) by that nested lambda,
797 /// until its instantiation. But we still need to capture it in the
798 /// enclosing lambda if all intervening lambdas can capture the variable.
800 llvm::SmallVector<Expr*, 4> PotentiallyCapturingExprs;
802 /// \brief Contains all variable-referring-expressions that refer
803 /// to local variables that are usable as constant expressions and
804 /// do not involve an odr-use (they may still need to be captured
805 /// if the enclosing full-expression is instantiation dependent).
806 llvm::SmallSet<Expr *, 8> NonODRUsedCapturingExprs;
808 /// Contains all of the variables defined in this lambda that shadow variables
809 /// that were defined in parent contexts. Used to avoid warnings when the
810 /// shadowed variables are uncaptured by this lambda.
811 struct ShadowedOuterDecl {
813 const VarDecl *ShadowedDecl;
815 llvm::SmallVector<ShadowedOuterDecl, 4> ShadowingDecls;
817 SourceLocation PotentialThisCaptureLocation;
819 LambdaScopeInfo(DiagnosticsEngine &Diag)
820 : CapturingScopeInfo(Diag, ImpCap_None), Lambda(nullptr),
821 CallOperator(nullptr), NumExplicitCaptures(0), Mutable(false),
822 ExplicitParams(false), Cleanup{},
823 ContainsUnexpandedParameterPack(false), AutoTemplateParameterDepth(0),
824 GLTemplateParameterList(nullptr) {
828 /// \brief Note when all explicit captures have been added.
829 void finishedExplicitCaptures() {
830 NumExplicitCaptures = Captures.size();
833 static bool classof(const FunctionScopeInfo *FSI) {
834 return FSI->Kind == SK_Lambda;
837 /// Is this scope known to be for a generic lambda? (This will be false until
838 /// we parse the first 'auto'-typed parameter.
839 bool isGenericLambda() const {
840 return !AutoTemplateParams.empty() || GLTemplateParameterList;
844 /// \brief Add a variable that might potentially be captured by the
845 /// lambda and therefore the enclosing lambdas.
847 /// This is also used by enclosing lambda's to speculatively capture
848 /// variables that nested lambda's - depending on their enclosing
849 /// specialization - might need to capture.
851 /// void f(int, int); <-- don't capture
852 /// void f(const int&, double); <-- capture
854 /// const int x = 10;
855 /// auto L = [=](auto a) { // capture 'x'
856 /// return [=](auto b) {
857 /// f(x, a); // we may or may not need to capture 'x'
861 void addPotentialCapture(Expr *VarExpr) {
862 assert(isa<DeclRefExpr>(VarExpr) || isa<MemberExpr>(VarExpr));
863 PotentiallyCapturingExprs.push_back(VarExpr);
866 void addPotentialThisCapture(SourceLocation Loc) {
867 PotentialThisCaptureLocation = Loc;
869 bool hasPotentialThisCapture() const {
870 return PotentialThisCaptureLocation.isValid();
873 /// \brief Mark a variable's reference in a lambda as non-odr using.
875 /// For generic lambdas, if a variable is named in a potentially evaluated
876 /// expression, where the enclosing full expression is dependent then we
877 /// must capture the variable (given a default capture).
878 /// This is accomplished by recording all references to variables
879 /// (DeclRefExprs or MemberExprs) within said nested lambda in its array of
880 /// PotentialCaptures. All such variables have to be captured by that lambda,
881 /// except for as described below.
882 /// If that variable is usable as a constant expression and is named in a
883 /// manner that does not involve its odr-use (e.g. undergoes
884 /// lvalue-to-rvalue conversion, or discarded) record that it is so. Upon the
885 /// act of analyzing the enclosing full expression (ActOnFinishFullExpr)
886 /// if we can determine that the full expression is not instantiation-
887 /// dependent, then we can entirely avoid its capture.
893 /// Interestingly, this strategy would involve a capture of n, even though
894 /// it's obviously not odr-used here, because the full-expression is
895 /// instantiation-dependent. It could be useful to avoid capturing such
896 /// variables, even when they are referred to in an instantiation-dependent
897 /// expression, if we can unambiguously determine that they shall never be
898 /// odr-used. This would involve removal of the variable-referring-expression
899 /// from the array of PotentialCaptures during the lvalue-to-rvalue
900 /// conversions. But per the working draft N3797, (post-chicago 2013) we must
901 /// capture such variables.
902 /// Before anyone is tempted to implement a strategy for not-capturing 'n',
903 /// consider the insightful warning in:
904 /// /cfe-commits/Week-of-Mon-20131104/092596.html
905 /// "The problem is that the set of captures for a lambda is part of the ABI
906 /// (since lambda layout can be made visible through inline functions and the
907 /// like), and there are no guarantees as to which cases we'll manage to build
908 /// an lvalue-to-rvalue conversion in, when parsing a template -- some
909 /// seemingly harmless change elsewhere in Sema could cause us to start or stop
910 /// building such a node. So we need a rule that anyone can implement and get
911 /// exactly the same result".
913 void markVariableExprAsNonODRUsed(Expr *CapturingVarExpr) {
914 assert(isa<DeclRefExpr>(CapturingVarExpr)
915 || isa<MemberExpr>(CapturingVarExpr));
916 NonODRUsedCapturingExprs.insert(CapturingVarExpr);
918 bool isVariableExprMarkedAsNonODRUsed(Expr *CapturingVarExpr) const {
919 assert(isa<DeclRefExpr>(CapturingVarExpr)
920 || isa<MemberExpr>(CapturingVarExpr));
921 return NonODRUsedCapturingExprs.count(CapturingVarExpr);
923 void removePotentialCapture(Expr *E) {
924 PotentiallyCapturingExprs.erase(
925 std::remove(PotentiallyCapturingExprs.begin(),
926 PotentiallyCapturingExprs.end(), E),
927 PotentiallyCapturingExprs.end());
929 void clearPotentialCaptures() {
930 PotentiallyCapturingExprs.clear();
931 PotentialThisCaptureLocation = SourceLocation();
933 unsigned getNumPotentialVariableCaptures() const {
934 return PotentiallyCapturingExprs.size();
937 bool hasPotentialCaptures() const {
938 return getNumPotentialVariableCaptures() ||
939 PotentialThisCaptureLocation.isValid();
942 // When passed the index, returns the VarDecl and Expr associated
944 void getPotentialVariableCapture(unsigned Idx, VarDecl *&VD, Expr *&E) const;
947 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy()
948 : Base(nullptr, false), Property(nullptr) {}
950 FunctionScopeInfo::WeakObjectProfileTy
951 FunctionScopeInfo::WeakObjectProfileTy::getSentinel() {
952 FunctionScopeInfo::WeakObjectProfileTy Result;
953 Result.Base.setInt(true);
957 template <typename ExprT>
958 void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) {
960 WeakUseVector &Uses = WeakObjectUses[WeakObjectProfileTy(E)];
961 Uses.push_back(WeakUseTy(E, IsRead));
965 CapturingScopeInfo::addThisCapture(bool isNested, SourceLocation Loc,
968 Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, QualType(),
970 CXXThisCaptureIndex = Captures.size();
973 } // end namespace sema
974 } // end namespace clang