1 //===- ScopeInfo.h - Information about a semantic context -------*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines FunctionScopeInfo and its subclasses, which contain
10 // information about a single function, block, lambda, or method body.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_SEMA_SCOPEINFO_H
15 #define LLVM_CLANG_SEMA_SCOPEINFO_H
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/ExprCXX.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 "clang/Sema/DeclSpec.h"
26 #include "llvm/ADT/DenseMap.h"
27 #include "llvm/ADT/DenseMapInfo.h"
28 #include "llvm/ADT/MapVector.h"
29 #include "llvm/ADT/PointerIntPair.h"
30 #include "llvm/ADT/SmallPtrSet.h"
31 #include "llvm/ADT/SmallSet.h"
32 #include "llvm/ADT/SmallVector.h"
33 #include "llvm/ADT/StringRef.h"
34 #include "llvm/ADT/StringSwitch.h"
35 #include "llvm/ADT/TinyPtrVector.h"
36 #include "llvm/Support/Casting.h"
37 #include "llvm/Support/ErrorHandling.h"
48 class ImplicitParamDecl;
50 class ObjCIvarRefExpr;
51 class ObjCMessageExpr;
52 class ObjCPropertyDecl;
53 class ObjCPropertyRefExpr;
60 class TemplateParameterList;
61 class TemplateTypeParmDecl;
66 /// Contains information about the compound statement currently being
68 class CompoundScopeInfo {
70 /// Whether this compound stamement contains `for' or `while' loops
71 /// with empty bodies.
72 bool HasEmptyLoopBodies = false;
74 /// Whether this compound statement corresponds to a GNU statement
78 CompoundScopeInfo(bool IsStmtExpr) : IsStmtExpr(IsStmtExpr) {}
80 void setHasEmptyLoopBodies() {
81 HasEmptyLoopBodies = true;
85 class PossiblyUnreachableDiag {
89 llvm::TinyPtrVector<const Stmt*> Stmts;
91 PossiblyUnreachableDiag(const PartialDiagnostic &PD, SourceLocation Loc,
92 ArrayRef<const Stmt *> Stmts)
93 : PD(PD), Loc(Loc), Stmts(Stmts) {}
96 /// Retains information about a function, method, or block that is
97 /// currently being parsed.
98 class FunctionScopeInfo {
108 /// What kind of scope we are describing.
111 /// Whether this function contains a VLA, \@try, try, C++
112 /// initializer, or anything else that can't be jumped past.
113 bool HasBranchProtectedScope : 1;
115 /// Whether this function contains any switches or direct gotos.
116 bool HasBranchIntoScope : 1;
118 /// Whether this function contains any indirect gotos.
119 bool HasIndirectGoto : 1;
121 /// Whether a statement was dropped because it was invalid.
122 bool HasDroppedStmt : 1;
124 /// True if current scope is for OpenMP declare reduction combiner.
125 bool HasOMPDeclareReductionCombiner : 1;
127 /// Whether there is a fallthrough statement in this function.
128 bool HasFallthroughStmt : 1;
130 /// Whether we make reference to a declaration that could be
132 bool HasPotentialAvailabilityViolations : 1;
134 /// A flag that is set when parsing a method that must call super's
135 /// implementation, such as \c -dealloc, \c -finalize, or any method marked
136 /// with \c __attribute__((objc_requires_super)).
137 bool ObjCShouldCallSuper : 1;
139 /// True when this is a method marked as a designated initializer.
140 bool ObjCIsDesignatedInit : 1;
142 /// This starts true for a method marked as designated initializer and will
143 /// be set to false if there is an invocation to a designated initializer of
145 bool ObjCWarnForNoDesignatedInitChain : 1;
147 /// True when this is an initializer method not marked as a designated
148 /// initializer within a class that has at least one initializer marked as a
149 /// designated initializer.
150 bool ObjCIsSecondaryInit : 1;
152 /// This starts true for a secondary initializer method and will be set to
153 /// false if there is an invocation of an initializer on 'self'.
154 bool ObjCWarnForNoInitDelegation : 1;
156 /// True only when this function has not already built, or attempted
157 /// to build, the initial and final coroutine suspend points
158 bool NeedsCoroutineSuspends : 1;
160 /// An enumeration represeting the kind of the first coroutine statement
161 /// in the function. One of co_return, co_await, or co_yield.
162 unsigned char FirstCoroutineStmtKind : 2;
164 /// First coroutine statement in the current function.
165 /// (ex co_return, co_await, co_yield)
166 SourceLocation FirstCoroutineStmtLoc;
168 /// First 'return' statement in the current function.
169 SourceLocation FirstReturnLoc;
171 /// First C++ 'try' statement in the current function.
172 SourceLocation FirstCXXTryLoc;
174 /// First SEH '__try' statement in the current function.
175 SourceLocation FirstSEHTryLoc;
177 /// Used to determine if errors occurred in this function or block.
178 DiagnosticErrorTrap ErrorTrap;
180 /// A SwitchStmt, along with a flag indicating if its list of case statements
181 /// is incomplete (because we dropped an invalid one while parsing).
182 using SwitchInfo = llvm::PointerIntPair<SwitchStmt*, 1, bool>;
184 /// SwitchStack - This is the current set of active switch statements in the
186 SmallVector<SwitchInfo, 8> SwitchStack;
188 /// The list of return statements that occur within the function or
189 /// block, if there is any chance of applying the named return value
190 /// optimization, or if we need to infer a return type.
191 SmallVector<ReturnStmt*, 4> Returns;
193 /// The promise object for this coroutine, if any.
194 VarDecl *CoroutinePromise = nullptr;
196 /// A mapping between the coroutine function parameters that were moved
197 /// to the coroutine frame, and their move statements.
198 llvm::SmallMapVector<ParmVarDecl *, Stmt *, 4> CoroutineParameterMoves;
200 /// The initial and final coroutine suspend points.
201 std::pair<Stmt *, Stmt *> CoroutineSuspends;
203 /// The stack of currently active compound stamement scopes in the
205 SmallVector<CompoundScopeInfo, 4> CompoundScopes;
207 /// The set of blocks that are introduced in this function.
208 llvm::SmallPtrSet<const BlockDecl *, 1> Blocks;
210 /// The set of __block variables that are introduced in this function.
211 llvm::TinyPtrVector<VarDecl *> ByrefBlockVars;
213 /// A list of PartialDiagnostics created but delayed within the
214 /// current function scope. These diagnostics are vetted for reachability
215 /// prior to being emitted.
216 SmallVector<PossiblyUnreachableDiag, 4> PossiblyUnreachableDiags;
218 /// A list of parameters which have the nonnull attribute and are
219 /// modified in the function.
220 llvm::SmallPtrSet<const ParmVarDecl *, 8> ModifiedNonNullParams;
223 /// Represents a simple identification of a weak object.
225 /// Part of the implementation of -Wrepeated-use-of-weak.
227 /// This is used to determine if two weak accesses refer to the same object.
228 /// Here are some examples of how various accesses are "profiled":
230 /// Access Expression | "Base" Decl | "Property" Decl
231 /// :---------------: | :-----------------: | :------------------------------:
232 /// self.property | self (VarDecl) | property (ObjCPropertyDecl)
233 /// self.implicitProp | self (VarDecl) | -implicitProp (ObjCMethodDecl)
234 /// self->ivar.prop | ivar (ObjCIvarDecl) | prop (ObjCPropertyDecl)
235 /// cxxObj.obj.prop | obj (FieldDecl) | prop (ObjCPropertyDecl)
236 /// [self foo].prop | 0 (unknown) | prop (ObjCPropertyDecl)
237 /// self.prop1.prop2 | prop1 (ObjCPropertyDecl) | prop2 (ObjCPropertyDecl)
238 /// MyClass.prop | MyClass (ObjCInterfaceDecl) | -prop (ObjCMethodDecl)
239 /// MyClass.foo.prop | +foo (ObjCMethodDecl) | -prop (ObjCPropertyDecl)
240 /// weakVar | 0 (known) | weakVar (VarDecl)
241 /// self->weakIvar | self (VarDecl) | weakIvar (ObjCIvarDecl)
243 /// Objects are identified with only two Decls to make it reasonably fast to
245 class WeakObjectProfileTy {
246 /// The base object decl, as described in the class documentation.
248 /// The extra flag is "true" if the Base and Property are enough to uniquely
249 /// identify the object in memory.
251 /// \sa isExactProfile()
252 using BaseInfoTy = llvm::PointerIntPair<const NamedDecl *, 1, bool>;
255 /// The "property" decl, as described in the class documentation.
257 /// Note that this may not actually be an ObjCPropertyDecl, e.g. in the
258 /// case of "implicit" properties (regular methods accessed via dot syntax).
259 const NamedDecl *Property = nullptr;
261 /// Used to find the proper base profile for a given base expression.
262 static BaseInfoTy getBaseInfo(const Expr *BaseE);
264 inline WeakObjectProfileTy();
265 static inline WeakObjectProfileTy getSentinel();
268 WeakObjectProfileTy(const ObjCPropertyRefExpr *RE);
269 WeakObjectProfileTy(const Expr *Base, const ObjCPropertyDecl *Property);
270 WeakObjectProfileTy(const DeclRefExpr *RE);
271 WeakObjectProfileTy(const ObjCIvarRefExpr *RE);
273 const NamedDecl *getBase() const { return Base.getPointer(); }
274 const NamedDecl *getProperty() const { return Property; }
276 /// Returns true if the object base specifies a known object in memory,
277 /// rather than, say, an instance variable or property of another object.
279 /// Note that this ignores the effects of aliasing; that is, \c foo.bar is
280 /// considered an exact profile if \c foo is a local variable, even if
281 /// another variable \c foo2 refers to the same object as \c foo.
283 /// For increased precision, accesses with base variables that are
284 /// properties or ivars of 'self' (e.g. self.prop1.prop2) are considered to
285 /// be exact, though this is not true for arbitrary variables
286 /// (foo.prop1.prop2).
287 bool isExactProfile() const {
288 return Base.getInt();
291 bool operator==(const WeakObjectProfileTy &Other) const {
292 return Base == Other.Base && Property == Other.Property;
295 // For use in DenseMap.
296 // We can't specialize the usual llvm::DenseMapInfo at the end of the file
297 // because by that point the DenseMap in FunctionScopeInfo has already been
301 static inline WeakObjectProfileTy getEmptyKey() {
302 return WeakObjectProfileTy();
305 static inline WeakObjectProfileTy getTombstoneKey() {
306 return WeakObjectProfileTy::getSentinel();
309 static unsigned getHashValue(const WeakObjectProfileTy &Val) {
310 using Pair = std::pair<BaseInfoTy, const NamedDecl *>;
312 return llvm::DenseMapInfo<Pair>::getHashValue(Pair(Val.Base,
316 static bool isEqual(const WeakObjectProfileTy &LHS,
317 const WeakObjectProfileTy &RHS) {
323 /// Represents a single use of a weak object.
325 /// Stores both the expression and whether the access is potentially unsafe
326 /// (i.e. it could potentially be warned about).
328 /// Part of the implementation of -Wrepeated-use-of-weak.
330 llvm::PointerIntPair<const Expr *, 1, bool> Rep;
333 WeakUseTy(const Expr *Use, bool IsRead) : Rep(Use, IsRead) {}
335 const Expr *getUseExpr() const { return Rep.getPointer(); }
336 bool isUnsafe() const { return Rep.getInt(); }
337 void markSafe() { Rep.setInt(false); }
339 bool operator==(const WeakUseTy &Other) const {
340 return Rep == Other.Rep;
344 /// Used to collect uses of a particular weak object in a function body.
346 /// Part of the implementation of -Wrepeated-use-of-weak.
347 using WeakUseVector = SmallVector<WeakUseTy, 4>;
349 /// Used to collect all uses of weak objects in a function body.
351 /// Part of the implementation of -Wrepeated-use-of-weak.
352 using WeakObjectUseMap =
353 llvm::SmallDenseMap<WeakObjectProfileTy, WeakUseVector, 8,
354 WeakObjectProfileTy::DenseMapInfo>;
357 /// Used to collect all uses of weak objects in this function body.
359 /// Part of the implementation of -Wrepeated-use-of-weak.
360 WeakObjectUseMap WeakObjectUses;
363 FunctionScopeInfo(const FunctionScopeInfo&) = default;
366 FunctionScopeInfo(DiagnosticsEngine &Diag)
367 : Kind(SK_Function), HasBranchProtectedScope(false),
368 HasBranchIntoScope(false), HasIndirectGoto(false),
369 HasDroppedStmt(false), HasOMPDeclareReductionCombiner(false),
370 HasFallthroughStmt(false), HasPotentialAvailabilityViolations(false),
371 ObjCShouldCallSuper(false), ObjCIsDesignatedInit(false),
372 ObjCWarnForNoDesignatedInitChain(false), ObjCIsSecondaryInit(false),
373 ObjCWarnForNoInitDelegation(false), NeedsCoroutineSuspends(true),
376 virtual ~FunctionScopeInfo();
378 /// Record that a weak object was accessed.
380 /// Part of the implementation of -Wrepeated-use-of-weak.
381 template <typename ExprT>
382 inline void recordUseOfWeak(const ExprT *E, bool IsRead = true);
384 void recordUseOfWeak(const ObjCMessageExpr *Msg,
385 const ObjCPropertyDecl *Prop);
387 /// Record that a given expression is a "safe" access of a weak object (e.g.
388 /// assigning it to a strong variable.)
390 /// Part of the implementation of -Wrepeated-use-of-weak.
391 void markSafeWeakUse(const Expr *E);
393 const WeakObjectUseMap &getWeakObjectUses() const {
394 return WeakObjectUses;
397 void setHasBranchIntoScope() {
398 HasBranchIntoScope = true;
401 void setHasBranchProtectedScope() {
402 HasBranchProtectedScope = true;
405 void setHasIndirectGoto() {
406 HasIndirectGoto = true;
409 void setHasDroppedStmt() {
410 HasDroppedStmt = true;
413 void setHasOMPDeclareReductionCombiner() {
414 HasOMPDeclareReductionCombiner = true;
417 void setHasFallthroughStmt() {
418 HasFallthroughStmt = true;
421 void setHasCXXTry(SourceLocation TryLoc) {
422 setHasBranchProtectedScope();
423 FirstCXXTryLoc = TryLoc;
426 void setHasSEHTry(SourceLocation TryLoc) {
427 setHasBranchProtectedScope();
428 FirstSEHTryLoc = TryLoc;
431 bool NeedsScopeChecking() const {
432 return !HasDroppedStmt &&
434 (HasBranchProtectedScope && HasBranchIntoScope));
437 // Add a block introduced in this function.
438 void addBlock(const BlockDecl *BD) {
442 // Add a __block variable introduced in this function.
443 void addByrefBlockVar(VarDecl *VD) {
444 ByrefBlockVars.push_back(VD);
447 bool isCoroutine() const { return !FirstCoroutineStmtLoc.isInvalid(); }
449 void setFirstCoroutineStmt(SourceLocation Loc, StringRef Keyword) {
450 assert(FirstCoroutineStmtLoc.isInvalid() &&
451 "first coroutine statement location already set");
452 FirstCoroutineStmtLoc = Loc;
453 FirstCoroutineStmtKind = llvm::StringSwitch<unsigned char>(Keyword)
454 .Case("co_return", 0)
456 .Case("co_yield", 2);
459 StringRef getFirstCoroutineStmtKeyword() const {
460 assert(FirstCoroutineStmtLoc.isValid()
461 && "no coroutine statement available");
462 switch (FirstCoroutineStmtKind) {
463 case 0: return "co_return";
464 case 1: return "co_await";
465 case 2: return "co_yield";
467 llvm_unreachable("FirstCoroutineStmtKind has an invalid value");
471 void setNeedsCoroutineSuspends(bool value = true) {
472 assert((!value || CoroutineSuspends.first == nullptr) &&
473 "we already have valid suspend points");
474 NeedsCoroutineSuspends = value;
477 bool hasInvalidCoroutineSuspends() const {
478 return !NeedsCoroutineSuspends && CoroutineSuspends.first == nullptr;
481 void setCoroutineSuspends(Stmt *Initial, Stmt *Final) {
482 assert(Initial && Final && "suspend points cannot be null");
483 assert(CoroutineSuspends.first == nullptr && "suspend points already set");
484 NeedsCoroutineSuspends = false;
485 CoroutineSuspends.first = Initial;
486 CoroutineSuspends.second = Final;
489 /// Clear out the information in this function scope, making it
490 /// suitable for reuse.
493 bool isPlainFunction() const { return Kind == SK_Function; }
497 // There are three categories of capture: capturing 'this', capturing
498 // local variables, and C++1y initialized captures (which can have an
499 // arbitrary initializer, and don't really capture in the traditional
502 // There are three ways to capture a local variable:
503 // - capture by copy in the C++11 sense,
504 // - capture by reference in the C++11 sense, and
505 // - __block capture.
506 // Lambdas explicitly specify capture by copy or capture by reference.
507 // For blocks, __block capture applies to variables with that annotation,
508 // variables of reference type are captured by reference, and other
509 // variables are captured by copy.
511 Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_VLA
515 /// If Kind == Cap_VLA, the captured type.
516 const VariableArrayType *CapturedVLA;
518 /// Otherwise, the captured variable (if any).
519 VarDecl *CapturedVar;
522 /// The source location at which the first capture occurred.
525 /// The location of the ellipsis that expands a parameter pack.
526 SourceLocation EllipsisLoc;
528 /// The type as it was captured, which is the type of the non-static data
529 /// member that would hold the capture.
530 QualType CaptureType;
532 /// The CaptureKind of this capture.
535 /// Whether this is a nested capture (a capture of an enclosing capturing
536 /// scope's capture).
539 /// Whether this is a capture of '*this'.
540 unsigned CapturesThis : 1;
542 /// Whether an explicit capture has been odr-used in the body of the
544 unsigned ODRUsed : 1;
546 /// Whether an explicit capture has been non-odr-used in the body of
548 unsigned NonODRUsed : 1;
550 /// Whether the capture is invalid (a capture was required but the entity is
552 unsigned Invalid : 1;
555 Capture(VarDecl *Var, bool Block, bool ByRef, bool IsNested,
556 SourceLocation Loc, SourceLocation EllipsisLoc, QualType CaptureType,
558 : CapturedVar(Var), Loc(Loc), EllipsisLoc(EllipsisLoc),
559 CaptureType(CaptureType),
560 Kind(Block ? Cap_Block : ByRef ? Cap_ByRef : Cap_ByCopy),
561 Nested(IsNested), CapturesThis(false), ODRUsed(false),
562 NonODRUsed(false), Invalid(Invalid) {}
564 enum IsThisCapture { ThisCapture };
565 Capture(IsThisCapture, bool IsNested, SourceLocation Loc,
566 QualType CaptureType, const bool ByCopy, bool Invalid)
567 : Loc(Loc), CaptureType(CaptureType),
568 Kind(ByCopy ? Cap_ByCopy : Cap_ByRef), Nested(IsNested),
569 CapturesThis(true), ODRUsed(false), NonODRUsed(false),
572 enum IsVLACapture { VLACapture };
573 Capture(IsVLACapture, const VariableArrayType *VLA, bool IsNested,
574 SourceLocation Loc, QualType CaptureType)
575 : CapturedVLA(VLA), Loc(Loc), CaptureType(CaptureType), Kind(Cap_VLA),
576 Nested(IsNested), CapturesThis(false), ODRUsed(false),
577 NonODRUsed(false), Invalid(false) {}
579 bool isThisCapture() const { return CapturesThis; }
580 bool isVariableCapture() const {
581 return !isThisCapture() && !isVLATypeCapture();
584 bool isCopyCapture() const { return Kind == Cap_ByCopy; }
585 bool isReferenceCapture() const { return Kind == Cap_ByRef; }
586 bool isBlockCapture() const { return Kind == Cap_Block; }
587 bool isVLATypeCapture() const { return Kind == Cap_VLA; }
589 bool isNested() const { return Nested; }
591 bool isInvalid() const { return Invalid; }
593 /// Determine whether this capture is an init-capture.
594 bool isInitCapture() const;
596 bool isODRUsed() const { return ODRUsed; }
597 bool isNonODRUsed() const { return NonODRUsed; }
598 void markUsed(bool IsODRUse) {
605 VarDecl *getVariable() const {
606 assert(isVariableCapture());
610 const VariableArrayType *getCapturedVLAType() const {
611 assert(isVLATypeCapture());
615 /// Retrieve the location at which this variable was captured.
616 SourceLocation getLocation() const { return Loc; }
618 /// Retrieve the source location of the ellipsis, whose presence
619 /// indicates that the capture is a pack expansion.
620 SourceLocation getEllipsisLoc() const { return EllipsisLoc; }
622 /// Retrieve the capture type for this capture, which is effectively
623 /// the type of the non-static data member in the lambda/block structure
624 /// that would store this capture.
625 QualType getCaptureType() const { return CaptureType; }
628 class CapturingScopeInfo : public FunctionScopeInfo {
630 CapturingScopeInfo(const CapturingScopeInfo&) = default;
633 enum ImplicitCaptureStyle {
634 ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block,
635 ImpCap_CapturedRegion
638 ImplicitCaptureStyle ImpCaptureStyle;
640 CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style)
641 : FunctionScopeInfo(Diag), ImpCaptureStyle(Style) {}
643 /// CaptureMap - A map of captured variables to (index+1) into Captures.
644 llvm::DenseMap<VarDecl*, unsigned> CaptureMap;
646 /// CXXThisCaptureIndex - The (index+1) of the capture of 'this';
647 /// zero if 'this' is not captured.
648 unsigned CXXThisCaptureIndex = 0;
650 /// Captures - The captures.
651 SmallVector<Capture, 4> Captures;
653 /// - Whether the target type of return statements in this context
654 /// is deduced (e.g. a lambda or block with omitted return type).
655 bool HasImplicitReturnType = false;
657 /// ReturnType - The target type of return statements in this context,
658 /// or null if unknown.
661 void addCapture(VarDecl *Var, bool isBlock, bool isByref, bool isNested,
662 SourceLocation Loc, SourceLocation EllipsisLoc,
663 QualType CaptureType, bool Invalid) {
664 Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc,
665 EllipsisLoc, CaptureType, Invalid));
666 CaptureMap[Var] = Captures.size();
669 void addVLATypeCapture(SourceLocation Loc, const VariableArrayType *VLAType,
670 QualType CaptureType) {
671 Captures.push_back(Capture(Capture::VLACapture, VLAType,
672 /*FIXME: IsNested*/ false, Loc, CaptureType));
675 void addThisCapture(bool isNested, SourceLocation Loc, QualType CaptureType,
678 /// Determine whether the C++ 'this' is captured.
679 bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; }
681 /// Retrieve the capture of C++ 'this', if it has been captured.
682 Capture &getCXXThisCapture() {
683 assert(isCXXThisCaptured() && "this has not been captured");
684 return Captures[CXXThisCaptureIndex - 1];
687 /// Determine whether the given variable has been captured.
688 bool isCaptured(VarDecl *Var) const {
689 return CaptureMap.count(Var);
692 /// Determine whether the given variable-array type has been captured.
693 bool isVLATypeCaptured(const VariableArrayType *VAT) const;
695 /// Retrieve the capture of the given variable, if it has been
696 /// captured already.
697 Capture &getCapture(VarDecl *Var) {
698 assert(isCaptured(Var) && "Variable has not been captured");
699 return Captures[CaptureMap[Var] - 1];
702 const Capture &getCapture(VarDecl *Var) const {
703 llvm::DenseMap<VarDecl*, unsigned>::const_iterator Known
704 = CaptureMap.find(Var);
705 assert(Known != CaptureMap.end() && "Variable has not been captured");
706 return Captures[Known->second - 1];
709 static bool classof(const FunctionScopeInfo *FSI) {
710 return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda
711 || FSI->Kind == SK_CapturedRegion;
715 /// Retains information about a block that is currently being parsed.
716 class BlockScopeInfo final : public CapturingScopeInfo {
720 /// TheScope - This is the scope for the block itself, which contains
724 /// BlockType - The function type of the block, if one was given.
725 /// Its return type may be BuiltinType::Dependent.
726 QualType FunctionType;
728 BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block)
729 : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block),
730 TheScope(BlockScope) {
734 ~BlockScopeInfo() override;
736 static bool classof(const FunctionScopeInfo *FSI) {
737 return FSI->Kind == SK_Block;
741 /// Retains information about a captured region.
742 class CapturedRegionScopeInfo final : public CapturingScopeInfo {
744 /// The CapturedDecl for this statement.
745 CapturedDecl *TheCapturedDecl;
747 /// The captured record type.
748 RecordDecl *TheRecordDecl;
750 /// This is the enclosing scope of the captured region.
753 /// The implicit parameter for the captured variables.
754 ImplicitParamDecl *ContextParam;
756 /// The kind of captured region.
757 unsigned short CapRegionKind;
759 unsigned short OpenMPLevel;
760 unsigned short OpenMPCaptureLevel;
762 CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD,
763 RecordDecl *RD, ImplicitParamDecl *Context,
764 CapturedRegionKind K, unsigned OpenMPLevel,
765 unsigned OpenMPCaptureLevel)
766 : CapturingScopeInfo(Diag, ImpCap_CapturedRegion),
767 TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S),
768 ContextParam(Context), CapRegionKind(K), OpenMPLevel(OpenMPLevel),
769 OpenMPCaptureLevel(OpenMPCaptureLevel) {
770 Kind = SK_CapturedRegion;
773 ~CapturedRegionScopeInfo() override;
775 /// A descriptive name for the kind of captured region this is.
776 StringRef getRegionName() const {
777 switch (CapRegionKind) {
779 return "default captured statement";
780 case CR_ObjCAtFinally:
781 return "Objective-C @finally statement";
783 return "OpenMP region";
785 llvm_unreachable("Invalid captured region kind!");
788 static bool classof(const FunctionScopeInfo *FSI) {
789 return FSI->Kind == SK_CapturedRegion;
793 class LambdaScopeInfo final :
794 public CapturingScopeInfo, public InventedTemplateParameterInfo {
796 /// The class that describes the lambda.
797 CXXRecordDecl *Lambda = nullptr;
799 /// The lambda's compiler-generated \c operator().
800 CXXMethodDecl *CallOperator = nullptr;
802 /// Source range covering the lambda introducer [...].
803 SourceRange IntroducerRange;
805 /// Source location of the '&' or '=' specifying the default capture
807 SourceLocation CaptureDefaultLoc;
809 /// The number of captures in the \c Captures list that are
810 /// explicit captures.
811 unsigned NumExplicitCaptures = 0;
813 /// Whether this is a mutable lambda.
814 bool Mutable = false;
816 /// Whether the (empty) parameter list is explicit.
817 bool ExplicitParams = false;
819 /// Whether any of the capture expressions requires cleanups.
822 /// Whether the lambda contains an unexpanded parameter pack.
823 bool ContainsUnexpandedParameterPack = false;
825 /// Packs introduced by this lambda, if any.
826 SmallVector<NamedDecl*, 4> LocalPacks;
828 /// Source range covering the explicit template parameter list (if it exists).
829 SourceRange ExplicitTemplateParamsRange;
831 /// If this is a generic lambda, and the template parameter
832 /// list has been created (from the TemplateParams) then store
833 /// a reference to it (cache it to avoid reconstructing it).
834 TemplateParameterList *GLTemplateParameterList = nullptr;
836 /// Contains all variable-referring-expressions (i.e. DeclRefExprs
837 /// or MemberExprs) that refer to local variables in a generic lambda
838 /// or a lambda in a potentially-evaluated-if-used context.
840 /// Potentially capturable variables of a nested lambda that might need
841 /// to be captured by the lambda are housed here.
842 /// This is specifically useful for generic lambdas or
843 /// lambdas within a potentially evaluated-if-used context.
844 /// If an enclosing variable is named in an expression of a lambda nested
845 /// within a generic lambda, we don't always know know whether the variable
846 /// will truly be odr-used (i.e. need to be captured) by that nested lambda,
847 /// until its instantiation. But we still need to capture it in the
848 /// enclosing lambda if all intervening lambdas can capture the variable.
849 llvm::SmallVector<Expr*, 4> PotentiallyCapturingExprs;
851 /// Contains all variable-referring-expressions that refer
852 /// to local variables that are usable as constant expressions and
853 /// do not involve an odr-use (they may still need to be captured
854 /// if the enclosing full-expression is instantiation dependent).
855 llvm::SmallSet<Expr *, 8> NonODRUsedCapturingExprs;
857 /// A map of explicit capture indices to their introducer source ranges.
858 llvm::DenseMap<unsigned, SourceRange> ExplicitCaptureRanges;
860 /// Contains all of the variables defined in this lambda that shadow variables
861 /// that were defined in parent contexts. Used to avoid warnings when the
862 /// shadowed variables are uncaptured by this lambda.
863 struct ShadowedOuterDecl {
865 const VarDecl *ShadowedDecl;
867 llvm::SmallVector<ShadowedOuterDecl, 4> ShadowingDecls;
869 SourceLocation PotentialThisCaptureLocation;
871 LambdaScopeInfo(DiagnosticsEngine &Diag)
872 : CapturingScopeInfo(Diag, ImpCap_None) {
876 /// Note when all explicit captures have been added.
877 void finishedExplicitCaptures() {
878 NumExplicitCaptures = Captures.size();
881 static bool classof(const FunctionScopeInfo *FSI) {
882 return FSI->Kind == SK_Lambda;
885 /// Is this scope known to be for a generic lambda? (This will be false until
886 /// we parse a template parameter list or the first 'auto'-typed parameter).
887 bool isGenericLambda() const {
888 return !TemplateParams.empty() || GLTemplateParameterList;
891 /// Add a variable that might potentially be captured by the
892 /// lambda and therefore the enclosing lambdas.
894 /// This is also used by enclosing lambda's to speculatively capture
895 /// variables that nested lambda's - depending on their enclosing
896 /// specialization - might need to capture.
898 /// void f(int, int); <-- don't capture
899 /// void f(const int&, double); <-- capture
901 /// const int x = 10;
902 /// auto L = [=](auto a) { // capture 'x'
903 /// return [=](auto b) {
904 /// f(x, a); // we may or may not need to capture 'x'
908 void addPotentialCapture(Expr *VarExpr) {
909 assert(isa<DeclRefExpr>(VarExpr) || isa<MemberExpr>(VarExpr) ||
910 isa<FunctionParmPackExpr>(VarExpr));
911 PotentiallyCapturingExprs.push_back(VarExpr);
914 void addPotentialThisCapture(SourceLocation Loc) {
915 PotentialThisCaptureLocation = Loc;
918 bool hasPotentialThisCapture() const {
919 return PotentialThisCaptureLocation.isValid();
922 /// Mark a variable's reference in a lambda as non-odr using.
924 /// For generic lambdas, if a variable is named in a potentially evaluated
925 /// expression, where the enclosing full expression is dependent then we
926 /// must capture the variable (given a default capture).
927 /// This is accomplished by recording all references to variables
928 /// (DeclRefExprs or MemberExprs) within said nested lambda in its array of
929 /// PotentialCaptures. All such variables have to be captured by that lambda,
930 /// except for as described below.
931 /// If that variable is usable as a constant expression and is named in a
932 /// manner that does not involve its odr-use (e.g. undergoes
933 /// lvalue-to-rvalue conversion, or discarded) record that it is so. Upon the
934 /// act of analyzing the enclosing full expression (ActOnFinishFullExpr)
935 /// if we can determine that the full expression is not instantiation-
936 /// dependent, then we can entirely avoid its capture.
942 /// Interestingly, this strategy would involve a capture of n, even though
943 /// it's obviously not odr-used here, because the full-expression is
944 /// instantiation-dependent. It could be useful to avoid capturing such
945 /// variables, even when they are referred to in an instantiation-dependent
946 /// expression, if we can unambiguously determine that they shall never be
947 /// odr-used. This would involve removal of the variable-referring-expression
948 /// from the array of PotentialCaptures during the lvalue-to-rvalue
949 /// conversions. But per the working draft N3797, (post-chicago 2013) we must
950 /// capture such variables.
951 /// Before anyone is tempted to implement a strategy for not-capturing 'n',
952 /// consider the insightful warning in:
953 /// /cfe-commits/Week-of-Mon-20131104/092596.html
954 /// "The problem is that the set of captures for a lambda is part of the ABI
955 /// (since lambda layout can be made visible through inline functions and the
956 /// like), and there are no guarantees as to which cases we'll manage to build
957 /// an lvalue-to-rvalue conversion in, when parsing a template -- some
958 /// seemingly harmless change elsewhere in Sema could cause us to start or stop
959 /// building such a node. So we need a rule that anyone can implement and get
960 /// exactly the same result".
961 void markVariableExprAsNonODRUsed(Expr *CapturingVarExpr) {
962 assert(isa<DeclRefExpr>(CapturingVarExpr) ||
963 isa<MemberExpr>(CapturingVarExpr) ||
964 isa<FunctionParmPackExpr>(CapturingVarExpr));
965 NonODRUsedCapturingExprs.insert(CapturingVarExpr);
967 bool isVariableExprMarkedAsNonODRUsed(Expr *CapturingVarExpr) const {
968 assert(isa<DeclRefExpr>(CapturingVarExpr) ||
969 isa<MemberExpr>(CapturingVarExpr) ||
970 isa<FunctionParmPackExpr>(CapturingVarExpr));
971 return NonODRUsedCapturingExprs.count(CapturingVarExpr);
973 void removePotentialCapture(Expr *E) {
974 PotentiallyCapturingExprs.erase(
975 std::remove(PotentiallyCapturingExprs.begin(),
976 PotentiallyCapturingExprs.end(), E),
977 PotentiallyCapturingExprs.end());
979 void clearPotentialCaptures() {
980 PotentiallyCapturingExprs.clear();
981 PotentialThisCaptureLocation = SourceLocation();
983 unsigned getNumPotentialVariableCaptures() const {
984 return PotentiallyCapturingExprs.size();
987 bool hasPotentialCaptures() const {
988 return getNumPotentialVariableCaptures() ||
989 PotentialThisCaptureLocation.isValid();
992 void visitPotentialCaptures(
993 llvm::function_ref<void(VarDecl *, Expr *)> Callback) const;
996 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy()
997 : Base(nullptr, false) {}
999 FunctionScopeInfo::WeakObjectProfileTy
1000 FunctionScopeInfo::WeakObjectProfileTy::getSentinel() {
1001 FunctionScopeInfo::WeakObjectProfileTy Result;
1002 Result.Base.setInt(true);
1006 template <typename ExprT>
1007 void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) {
1009 WeakUseVector &Uses = WeakObjectUses[WeakObjectProfileTy(E)];
1010 Uses.push_back(WeakUseTy(E, IsRead));
1013 inline void CapturingScopeInfo::addThisCapture(bool isNested,
1015 QualType CaptureType,
1017 Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, CaptureType,
1018 ByCopy, /*Invalid*/ false));
1019 CXXThisCaptureIndex = Captures.size();
1024 } // namespace clang
1026 #endif // LLVM_CLANG_SEMA_SCOPEINFO_H