1 //===--- ScopeInfo.h - Information about a semantic context -----*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines FunctionScopeInfo and its subclasses, which contain
11 // information about a single function, block, lambda, or method body.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #ifndef LLVM_CLANG_SEMA_SCOPEINFO_H
16 #define LLVM_CLANG_SEMA_SCOPEINFO_H
17
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/Ownership.h"
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/SmallSet.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include <algorithm>
27
28 namespace clang {
29
30 class Decl;
31 class BlockDecl;
32 class CapturedDecl;
33 class CXXMethodDecl;
34 class FieldDecl;
35 class ObjCPropertyDecl;
36 class IdentifierInfo;
37 class ImplicitParamDecl;
38 class LabelDecl;
39 class ReturnStmt;
40 class Scope;
41 class SwitchStmt;
42 class TemplateTypeParmDecl;
43 class TemplateParameterList;
44 class VarDecl;
45 class ObjCIvarRefExpr;
46 class ObjCPropertyRefExpr;
47 class ObjCMessageExpr;
48
49 namespace sema {
50
51 /// \brief Contains information about the compound statement currently being
52 /// parsed.
53 class CompoundScopeInfo {
54 public:
CompoundScopeInfo()55 CompoundScopeInfo()
56 : HasEmptyLoopBodies(false) { }
57
58 /// \brief Whether this compound stamement contains `for' or `while' loops
59 /// with empty bodies.
60 bool HasEmptyLoopBodies;
61
setHasEmptyLoopBodies()62 void setHasEmptyLoopBodies() {
63 HasEmptyLoopBodies = true;
64 }
65 };
66
67 class PossiblyUnreachableDiag {
68 public:
69 PartialDiagnostic PD;
70 SourceLocation Loc;
71 const Stmt *stmt;
72
PossiblyUnreachableDiag(const PartialDiagnostic & PD,SourceLocation Loc,const Stmt * stmt)73 PossiblyUnreachableDiag(const PartialDiagnostic &PD, SourceLocation Loc,
74 const Stmt *stmt)
75 : PD(PD), Loc(Loc), stmt(stmt) {}
76 };
77
78 /// \brief Retains information about a function, method, or block that is
79 /// currently being parsed.
80 class FunctionScopeInfo {
81 protected:
82 enum ScopeKind {
83 SK_Function,
84 SK_Block,
85 SK_Lambda,
86 SK_CapturedRegion
87 };
88
89 public:
90 /// \brief What kind of scope we are describing.
91 ///
92 ScopeKind Kind;
93
94 /// \brief Whether this function contains a VLA, \@try, try, C++
95 /// initializer, or anything else that can't be jumped past.
96 bool HasBranchProtectedScope;
97
98 /// \brief Whether this function contains any switches or direct gotos.
99 bool HasBranchIntoScope;
100
101 /// \brief Whether this function contains any indirect gotos.
102 bool HasIndirectGoto;
103
104 /// \brief Whether a statement was dropped because it was invalid.
105 bool HasDroppedStmt;
106
107 /// A flag that is set when parsing a method that must call super's
108 /// implementation, such as \c -dealloc, \c -finalize, or any method marked
109 /// with \c __attribute__((objc_requires_super)).
110 bool ObjCShouldCallSuper;
111
112 /// True when this is a method marked as a designated initializer.
113 bool ObjCIsDesignatedInit;
114 /// This starts true for a method marked as designated initializer and will
115 /// be set to false if there is an invocation to a designated initializer of
116 /// the super class.
117 bool ObjCWarnForNoDesignatedInitChain;
118
119 /// True when this is an initializer method not marked as a designated
120 /// initializer within a class that has at least one initializer marked as a
121 /// designated initializer.
122 bool ObjCIsSecondaryInit;
123 /// This starts true for a secondary initializer method and will be set to
124 /// false if there is an invocation of an initializer on 'self'.
125 bool ObjCWarnForNoInitDelegation;
126
127 /// \brief Used to determine if errors occurred in this function or block.
128 DiagnosticErrorTrap ErrorTrap;
129
130 /// SwitchStack - This is the current set of active switch statements in the
131 /// block.
132 SmallVector<SwitchStmt*, 8> SwitchStack;
133
134 /// \brief The list of return statements that occur within the function or
135 /// block, if there is any chance of applying the named return value
136 /// optimization, or if we need to infer a return type.
137 SmallVector<ReturnStmt*, 4> Returns;
138
139 /// \brief The stack of currently active compound stamement scopes in the
140 /// function.
141 SmallVector<CompoundScopeInfo, 4> CompoundScopes;
142
143 /// \brief A list of PartialDiagnostics created but delayed within the
144 /// current function scope. These diagnostics are vetted for reachability
145 /// prior to being emitted.
146 SmallVector<PossiblyUnreachableDiag, 4> PossiblyUnreachableDiags;
147
148 /// \brief A list of parameters which have the nonnull attribute and are
149 /// modified in the function.
150 llvm::SmallPtrSet<const ParmVarDecl*, 8> ModifiedNonNullParams;
151
152 public:
153 /// Represents a simple identification of a weak object.
154 ///
155 /// Part of the implementation of -Wrepeated-use-of-weak.
156 ///
157 /// This is used to determine if two weak accesses refer to the same object.
158 /// Here are some examples of how various accesses are "profiled":
159 ///
160 /// Access Expression | "Base" Decl | "Property" Decl
161 /// :---------------: | :-----------------: | :------------------------------:
162 /// self.property | self (VarDecl) | property (ObjCPropertyDecl)
163 /// self.implicitProp | self (VarDecl) | -implicitProp (ObjCMethodDecl)
164 /// self->ivar.prop | ivar (ObjCIvarDecl) | prop (ObjCPropertyDecl)
165 /// cxxObj.obj.prop | obj (FieldDecl) | prop (ObjCPropertyDecl)
166 /// [self foo].prop | 0 (unknown) | prop (ObjCPropertyDecl)
167 /// self.prop1.prop2 | prop1 (ObjCPropertyDecl) | prop2 (ObjCPropertyDecl)
168 /// MyClass.prop | MyClass (ObjCInterfaceDecl) | -prop (ObjCMethodDecl)
169 /// weakVar | 0 (known) | weakVar (VarDecl)
170 /// self->weakIvar | self (VarDecl) | weakIvar (ObjCIvarDecl)
171 ///
172 /// Objects are identified with only two Decls to make it reasonably fast to
173 /// compare them.
174 class WeakObjectProfileTy {
175 /// The base object decl, as described in the class documentation.
176 ///
177 /// The extra flag is "true" if the Base and Property are enough to uniquely
178 /// identify the object in memory.
179 ///
180 /// \sa isExactProfile()
181 typedef llvm::PointerIntPair<const NamedDecl *, 1, bool> BaseInfoTy;
182 BaseInfoTy Base;
183
184 /// The "property" decl, as described in the class documentation.
185 ///
186 /// Note that this may not actually be an ObjCPropertyDecl, e.g. in the
187 /// case of "implicit" properties (regular methods accessed via dot syntax).
188 const NamedDecl *Property;
189
190 /// Used to find the proper base profile for a given base expression.
191 static BaseInfoTy getBaseInfo(const Expr *BaseE);
192
193 inline WeakObjectProfileTy();
194 static inline WeakObjectProfileTy getSentinel();
195
196 public:
197 WeakObjectProfileTy(const ObjCPropertyRefExpr *RE);
198 WeakObjectProfileTy(const Expr *Base, const ObjCPropertyDecl *Property);
199 WeakObjectProfileTy(const DeclRefExpr *RE);
200 WeakObjectProfileTy(const ObjCIvarRefExpr *RE);
201
getBase()202 const NamedDecl *getBase() const { return Base.getPointer(); }
getProperty()203 const NamedDecl *getProperty() const { return Property; }
204
205 /// Returns true if the object base specifies a known object in memory,
206 /// rather than, say, an instance variable or property of another object.
207 ///
208 /// Note that this ignores the effects of aliasing; that is, \c foo.bar is
209 /// considered an exact profile if \c foo is a local variable, even if
210 /// another variable \c foo2 refers to the same object as \c foo.
211 ///
212 /// For increased precision, accesses with base variables that are
213 /// properties or ivars of 'self' (e.g. self.prop1.prop2) are considered to
214 /// be exact, though this is not true for arbitrary variables
215 /// (foo.prop1.prop2).
isExactProfile()216 bool isExactProfile() const {
217 return Base.getInt();
218 }
219
220 bool operator==(const WeakObjectProfileTy &Other) const {
221 return Base == Other.Base && Property == Other.Property;
222 }
223
224 // For use in DenseMap.
225 // We can't specialize the usual llvm::DenseMapInfo at the end of the file
226 // because by that point the DenseMap in FunctionScopeInfo has already been
227 // instantiated.
228 class DenseMapInfo {
229 public:
getEmptyKey()230 static inline WeakObjectProfileTy getEmptyKey() {
231 return WeakObjectProfileTy();
232 }
getTombstoneKey()233 static inline WeakObjectProfileTy getTombstoneKey() {
234 return WeakObjectProfileTy::getSentinel();
235 }
236
getHashValue(const WeakObjectProfileTy & Val)237 static unsigned getHashValue(const WeakObjectProfileTy &Val) {
238 typedef std::pair<BaseInfoTy, const NamedDecl *> Pair;
239 return llvm::DenseMapInfo<Pair>::getHashValue(Pair(Val.Base,
240 Val.Property));
241 }
242
isEqual(const WeakObjectProfileTy & LHS,const WeakObjectProfileTy & RHS)243 static bool isEqual(const WeakObjectProfileTy &LHS,
244 const WeakObjectProfileTy &RHS) {
245 return LHS == RHS;
246 }
247 };
248 };
249
250 /// Represents a single use of a weak object.
251 ///
252 /// Stores both the expression and whether the access is potentially unsafe
253 /// (i.e. it could potentially be warned about).
254 ///
255 /// Part of the implementation of -Wrepeated-use-of-weak.
256 class WeakUseTy {
257 llvm::PointerIntPair<const Expr *, 1, bool> Rep;
258 public:
WeakUseTy(const Expr * Use,bool IsRead)259 WeakUseTy(const Expr *Use, bool IsRead) : Rep(Use, IsRead) {}
260
getUseExpr()261 const Expr *getUseExpr() const { return Rep.getPointer(); }
isUnsafe()262 bool isUnsafe() const { return Rep.getInt(); }
markSafe()263 void markSafe() { Rep.setInt(false); }
264
265 bool operator==(const WeakUseTy &Other) const {
266 return Rep == Other.Rep;
267 }
268 };
269
270 /// Used to collect uses of a particular weak object in a function body.
271 ///
272 /// Part of the implementation of -Wrepeated-use-of-weak.
273 typedef SmallVector<WeakUseTy, 4> WeakUseVector;
274
275 /// Used to collect all uses of weak objects in a function body.
276 ///
277 /// Part of the implementation of -Wrepeated-use-of-weak.
278 typedef llvm::SmallDenseMap<WeakObjectProfileTy, WeakUseVector, 8,
279 WeakObjectProfileTy::DenseMapInfo>
280 WeakObjectUseMap;
281
282 private:
283 /// Used to collect all uses of weak objects in this function body.
284 ///
285 /// Part of the implementation of -Wrepeated-use-of-weak.
286 WeakObjectUseMap WeakObjectUses;
287
288 public:
289 /// Record that a weak object was accessed.
290 ///
291 /// Part of the implementation of -Wrepeated-use-of-weak.
292 template <typename ExprT>
293 inline void recordUseOfWeak(const ExprT *E, bool IsRead = true);
294
295 void recordUseOfWeak(const ObjCMessageExpr *Msg,
296 const ObjCPropertyDecl *Prop);
297
298 /// Record that a given expression is a "safe" access of a weak object (e.g.
299 /// assigning it to a strong variable.)
300 ///
301 /// Part of the implementation of -Wrepeated-use-of-weak.
302 void markSafeWeakUse(const Expr *E);
303
getWeakObjectUses()304 const WeakObjectUseMap &getWeakObjectUses() const {
305 return WeakObjectUses;
306 }
307
setHasBranchIntoScope()308 void setHasBranchIntoScope() {
309 HasBranchIntoScope = true;
310 }
311
setHasBranchProtectedScope()312 void setHasBranchProtectedScope() {
313 HasBranchProtectedScope = true;
314 }
315
setHasIndirectGoto()316 void setHasIndirectGoto() {
317 HasIndirectGoto = true;
318 }
319
setHasDroppedStmt()320 void setHasDroppedStmt() {
321 HasDroppedStmt = true;
322 }
323
NeedsScopeChecking()324 bool NeedsScopeChecking() const {
325 return !HasDroppedStmt &&
326 (HasIndirectGoto ||
327 (HasBranchProtectedScope && HasBranchIntoScope));
328 }
329
FunctionScopeInfo(DiagnosticsEngine & Diag)330 FunctionScopeInfo(DiagnosticsEngine &Diag)
331 : Kind(SK_Function),
332 HasBranchProtectedScope(false),
333 HasBranchIntoScope(false),
334 HasIndirectGoto(false),
335 HasDroppedStmt(false),
336 ObjCShouldCallSuper(false),
337 ObjCIsDesignatedInit(false),
338 ObjCWarnForNoDesignatedInitChain(false),
339 ObjCIsSecondaryInit(false),
340 ObjCWarnForNoInitDelegation(false),
341 ErrorTrap(Diag) { }
342
343 virtual ~FunctionScopeInfo();
344
345 /// \brief Clear out the information in this function scope, making it
346 /// suitable for reuse.
347 void Clear();
348 };
349
350 class CapturingScopeInfo : public FunctionScopeInfo {
351 public:
352 enum ImplicitCaptureStyle {
353 ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block,
354 ImpCap_CapturedRegion
355 };
356
357 ImplicitCaptureStyle ImpCaptureStyle;
358
359 class Capture {
360 // There are three categories of capture: capturing 'this', capturing
361 // local variables, and C++1y initialized captures (which can have an
362 // arbitrary initializer, and don't really capture in the traditional
363 // sense at all).
364 //
365 // There are three ways to capture a local variable:
366 // - capture by copy in the C++11 sense,
367 // - capture by reference in the C++11 sense, and
368 // - __block capture.
369 // Lambdas explicitly specify capture by copy or capture by reference.
370 // For blocks, __block capture applies to variables with that annotation,
371 // variables of reference type are captured by reference, and other
372 // variables are captured by copy.
373 enum CaptureKind {
374 Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_This
375 };
376
377 /// The variable being captured (if we are not capturing 'this') and whether
378 /// this is a nested capture.
379 llvm::PointerIntPair<VarDecl*, 1, bool> VarAndNested;
380
381 /// Expression to initialize a field of the given type, and the kind of
382 /// capture (if this is a capture and not an init-capture). The expression
383 /// is only required if we are capturing ByVal and the variable's type has
384 /// a non-trivial copy constructor.
385 llvm::PointerIntPair<void *, 2, CaptureKind> InitExprAndCaptureKind;
386
387 /// \brief The source location at which the first capture occurred.
388 SourceLocation Loc;
389
390 /// \brief The location of the ellipsis that expands a parameter pack.
391 SourceLocation EllipsisLoc;
392
393 /// \brief The type as it was captured, which is in effect the type of the
394 /// non-static data member that would hold the capture.
395 QualType CaptureType;
396
397 public:
Capture(VarDecl * Var,bool Block,bool ByRef,bool IsNested,SourceLocation Loc,SourceLocation EllipsisLoc,QualType CaptureType,Expr * Cpy)398 Capture(VarDecl *Var, bool Block, bool ByRef, bool IsNested,
399 SourceLocation Loc, SourceLocation EllipsisLoc,
400 QualType CaptureType, Expr *Cpy)
401 : VarAndNested(Var, IsNested),
402 InitExprAndCaptureKind(Cpy, Block ? Cap_Block :
403 ByRef ? Cap_ByRef : Cap_ByCopy),
404 Loc(Loc), EllipsisLoc(EllipsisLoc), CaptureType(CaptureType) {}
405
406 enum IsThisCapture { ThisCapture };
Capture(IsThisCapture,bool IsNested,SourceLocation Loc,QualType CaptureType,Expr * Cpy)407 Capture(IsThisCapture, bool IsNested, SourceLocation Loc,
408 QualType CaptureType, Expr *Cpy)
409 : VarAndNested(nullptr, IsNested),
410 InitExprAndCaptureKind(Cpy, Cap_This),
411 Loc(Loc), EllipsisLoc(), CaptureType(CaptureType) {}
412
isThisCapture()413 bool isThisCapture() const {
414 return InitExprAndCaptureKind.getInt() == Cap_This;
415 }
isVariableCapture()416 bool isVariableCapture() const {
417 return InitExprAndCaptureKind.getInt() != Cap_This && !isVLATypeCapture();
418 }
isCopyCapture()419 bool isCopyCapture() const {
420 return InitExprAndCaptureKind.getInt() == Cap_ByCopy &&
421 !isVLATypeCapture();
422 }
isReferenceCapture()423 bool isReferenceCapture() const {
424 return InitExprAndCaptureKind.getInt() == Cap_ByRef;
425 }
isBlockCapture()426 bool isBlockCapture() const {
427 return InitExprAndCaptureKind.getInt() == Cap_Block;
428 }
isVLATypeCapture()429 bool isVLATypeCapture() const {
430 return InitExprAndCaptureKind.getInt() == Cap_ByCopy &&
431 getVariable() == nullptr;
432 }
isNested()433 bool isNested() const { return VarAndNested.getInt(); }
434
getVariable()435 VarDecl *getVariable() const {
436 return VarAndNested.getPointer();
437 }
438
439 /// \brief Retrieve the location at which this variable was captured.
getLocation()440 SourceLocation getLocation() const { return Loc; }
441
442 /// \brief Retrieve the source location of the ellipsis, whose presence
443 /// indicates that the capture is a pack expansion.
getEllipsisLoc()444 SourceLocation getEllipsisLoc() const { return EllipsisLoc; }
445
446 /// \brief Retrieve the capture type for this capture, which is effectively
447 /// the type of the non-static data member in the lambda/block structure
448 /// that would store this capture.
getCaptureType()449 QualType getCaptureType() const { return CaptureType; }
450
getInitExpr()451 Expr *getInitExpr() const {
452 assert(!isVLATypeCapture() && "no init expression for type capture");
453 return static_cast<Expr *>(InitExprAndCaptureKind.getPointer());
454 }
455 };
456
CapturingScopeInfo(DiagnosticsEngine & Diag,ImplicitCaptureStyle Style)457 CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style)
458 : FunctionScopeInfo(Diag), ImpCaptureStyle(Style), CXXThisCaptureIndex(0),
459 HasImplicitReturnType(false)
460 {}
461
462 /// CaptureMap - A map of captured variables to (index+1) into Captures.
463 llvm::DenseMap<VarDecl*, unsigned> CaptureMap;
464
465 /// CXXThisCaptureIndex - The (index+1) of the capture of 'this';
466 /// zero if 'this' is not captured.
467 unsigned CXXThisCaptureIndex;
468
469 /// Captures - The captures.
470 SmallVector<Capture, 4> Captures;
471
472 /// \brief - Whether the target type of return statements in this context
473 /// is deduced (e.g. a lambda or block with omitted return type).
474 bool HasImplicitReturnType;
475
476 /// ReturnType - The target type of return statements in this context,
477 /// or null if unknown.
478 QualType ReturnType;
479
addCapture(VarDecl * Var,bool isBlock,bool isByref,bool isNested,SourceLocation Loc,SourceLocation EllipsisLoc,QualType CaptureType,Expr * Cpy)480 void addCapture(VarDecl *Var, bool isBlock, bool isByref, bool isNested,
481 SourceLocation Loc, SourceLocation EllipsisLoc,
482 QualType CaptureType, Expr *Cpy) {
483 Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc,
484 EllipsisLoc, CaptureType, Cpy));
485 CaptureMap[Var] = Captures.size();
486 }
487
addVLATypeCapture(SourceLocation Loc,QualType CaptureType)488 void addVLATypeCapture(SourceLocation Loc, QualType CaptureType) {
489 Captures.push_back(Capture(/*Var*/ nullptr, /*isBlock*/ false,
490 /*isByref*/ false, /*isNested*/ false, Loc,
491 /*EllipsisLoc*/ SourceLocation(), CaptureType,
492 /*Cpy*/ nullptr));
493 }
494
495 void addThisCapture(bool isNested, SourceLocation Loc, QualType CaptureType,
496 Expr *Cpy);
497
498 /// \brief Determine whether the C++ 'this' is captured.
isCXXThisCaptured()499 bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; }
500
501 /// \brief Retrieve the capture of C++ 'this', if it has been captured.
getCXXThisCapture()502 Capture &getCXXThisCapture() {
503 assert(isCXXThisCaptured() && "this has not been captured");
504 return Captures[CXXThisCaptureIndex - 1];
505 }
506
507 /// \brief Determine whether the given variable has been captured.
isCaptured(VarDecl * Var)508 bool isCaptured(VarDecl *Var) const {
509 return CaptureMap.count(Var);
510 }
511
512 /// \brief Determine whether the given variable-array type has been captured.
513 bool isVLATypeCaptured(const VariableArrayType *VAT) const;
514
515 /// \brief Retrieve the capture of the given variable, if it has been
516 /// captured already.
getCapture(VarDecl * Var)517 Capture &getCapture(VarDecl *Var) {
518 assert(isCaptured(Var) && "Variable has not been captured");
519 return Captures[CaptureMap[Var] - 1];
520 }
521
getCapture(VarDecl * Var)522 const Capture &getCapture(VarDecl *Var) const {
523 llvm::DenseMap<VarDecl*, unsigned>::const_iterator Known
524 = CaptureMap.find(Var);
525 assert(Known != CaptureMap.end() && "Variable has not been captured");
526 return Captures[Known->second - 1];
527 }
528
classof(const FunctionScopeInfo * FSI)529 static bool classof(const FunctionScopeInfo *FSI) {
530 return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda
531 || FSI->Kind == SK_CapturedRegion;
532 }
533 };
534
535 /// \brief Retains information about a block that is currently being parsed.
536 class BlockScopeInfo : public CapturingScopeInfo {
537 public:
538 BlockDecl *TheDecl;
539
540 /// TheScope - This is the scope for the block itself, which contains
541 /// arguments etc.
542 Scope *TheScope;
543
544 /// BlockType - The function type of the block, if one was given.
545 /// Its return type may be BuiltinType::Dependent.
546 QualType FunctionType;
547
BlockScopeInfo(DiagnosticsEngine & Diag,Scope * BlockScope,BlockDecl * Block)548 BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block)
549 : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block),
550 TheScope(BlockScope)
551 {
552 Kind = SK_Block;
553 }
554
555 virtual ~BlockScopeInfo();
556
classof(const FunctionScopeInfo * FSI)557 static bool classof(const FunctionScopeInfo *FSI) {
558 return FSI->Kind == SK_Block;
559 }
560 };
561
562 /// \brief Retains information about a captured region.
563 class CapturedRegionScopeInfo: public CapturingScopeInfo {
564 public:
565 /// \brief The CapturedDecl for this statement.
566 CapturedDecl *TheCapturedDecl;
567 /// \brief The captured record type.
568 RecordDecl *TheRecordDecl;
569 /// \brief This is the enclosing scope of the captured region.
570 Scope *TheScope;
571 /// \brief The implicit parameter for the captured variables.
572 ImplicitParamDecl *ContextParam;
573 /// \brief The kind of captured region.
574 CapturedRegionKind CapRegionKind;
575
CapturedRegionScopeInfo(DiagnosticsEngine & Diag,Scope * S,CapturedDecl * CD,RecordDecl * RD,ImplicitParamDecl * Context,CapturedRegionKind K)576 CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD,
577 RecordDecl *RD, ImplicitParamDecl *Context,
578 CapturedRegionKind K)
579 : CapturingScopeInfo(Diag, ImpCap_CapturedRegion),
580 TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S),
581 ContextParam(Context), CapRegionKind(K)
582 {
583 Kind = SK_CapturedRegion;
584 }
585
586 virtual ~CapturedRegionScopeInfo();
587
588 /// \brief A descriptive name for the kind of captured region this is.
getRegionName()589 StringRef getRegionName() const {
590 switch (CapRegionKind) {
591 case CR_Default:
592 return "default captured statement";
593 case CR_OpenMP:
594 return "OpenMP region";
595 }
596 llvm_unreachable("Invalid captured region kind!");
597 }
598
classof(const FunctionScopeInfo * FSI)599 static bool classof(const FunctionScopeInfo *FSI) {
600 return FSI->Kind == SK_CapturedRegion;
601 }
602 };
603
604 class LambdaScopeInfo : public CapturingScopeInfo {
605 public:
606 /// \brief The class that describes the lambda.
607 CXXRecordDecl *Lambda;
608
609 /// \brief The lambda's compiler-generated \c operator().
610 CXXMethodDecl *CallOperator;
611
612 /// \brief Source range covering the lambda introducer [...].
613 SourceRange IntroducerRange;
614
615 /// \brief Source location of the '&' or '=' specifying the default capture
616 /// type, if any.
617 SourceLocation CaptureDefaultLoc;
618
619 /// \brief The number of captures in the \c Captures list that are
620 /// explicit captures.
621 unsigned NumExplicitCaptures;
622
623 /// \brief Whether this is a mutable lambda.
624 bool Mutable;
625
626 /// \brief Whether the (empty) parameter list is explicit.
627 bool ExplicitParams;
628
629 /// \brief Whether any of the capture expressions requires cleanups.
630 bool ExprNeedsCleanups;
631
632 /// \brief Whether the lambda contains an unexpanded parameter pack.
633 bool ContainsUnexpandedParameterPack;
634
635 /// \brief Variables used to index into by-copy array captures.
636 SmallVector<VarDecl *, 4> ArrayIndexVars;
637
638 /// \brief Offsets into the ArrayIndexVars array at which each capture starts
639 /// its list of array index variables.
640 SmallVector<unsigned, 4> ArrayIndexStarts;
641
642 /// \brief If this is a generic lambda, use this as the depth of
643 /// each 'auto' parameter, during initial AST construction.
644 unsigned AutoTemplateParameterDepth;
645
646 /// \brief Store the list of the auto parameters for a generic lambda.
647 /// If this is a generic lambda, store the list of the auto
648 /// parameters converted into TemplateTypeParmDecls into a vector
649 /// that can be used to construct the generic lambda's template
650 /// parameter list, during initial AST construction.
651 SmallVector<TemplateTypeParmDecl*, 4> AutoTemplateParams;
652
653 /// If this is a generic lambda, and the template parameter
654 /// list has been created (from the AutoTemplateParams) then
655 /// store a reference to it (cache it to avoid reconstructing it).
656 TemplateParameterList *GLTemplateParameterList;
657
658 /// \brief Contains all variable-referring-expressions (i.e. DeclRefExprs
659 /// or MemberExprs) that refer to local variables in a generic lambda
660 /// or a lambda in a potentially-evaluated-if-used context.
661 ///
662 /// Potentially capturable variables of a nested lambda that might need
663 /// to be captured by the lambda are housed here.
664 /// This is specifically useful for generic lambdas or
665 /// lambdas within a a potentially evaluated-if-used context.
666 /// If an enclosing variable is named in an expression of a lambda nested
667 /// within a generic lambda, we don't always know know whether the variable
668 /// will truly be odr-used (i.e. need to be captured) by that nested lambda,
669 /// until its instantiation. But we still need to capture it in the
670 /// enclosing lambda if all intervening lambdas can capture the variable.
671
672 llvm::SmallVector<Expr*, 4> PotentiallyCapturingExprs;
673
674 /// \brief Contains all variable-referring-expressions that refer
675 /// to local variables that are usable as constant expressions and
676 /// do not involve an odr-use (they may still need to be captured
677 /// if the enclosing full-expression is instantiation dependent).
678 llvm::SmallSet<Expr*, 8> NonODRUsedCapturingExprs;
679
680 SourceLocation PotentialThisCaptureLocation;
681
LambdaScopeInfo(DiagnosticsEngine & Diag)682 LambdaScopeInfo(DiagnosticsEngine &Diag)
683 : CapturingScopeInfo(Diag, ImpCap_None), Lambda(nullptr),
684 CallOperator(nullptr), NumExplicitCaptures(0), Mutable(false),
685 ExprNeedsCleanups(false), ContainsUnexpandedParameterPack(false),
686 AutoTemplateParameterDepth(0), GLTemplateParameterList(nullptr)
687 {
688 Kind = SK_Lambda;
689 }
690
691 virtual ~LambdaScopeInfo();
692
693 /// \brief Note when all explicit captures have been added.
finishedExplicitCaptures()694 void finishedExplicitCaptures() {
695 NumExplicitCaptures = Captures.size();
696 }
697
classof(const FunctionScopeInfo * FSI)698 static bool classof(const FunctionScopeInfo *FSI) {
699 return FSI->Kind == SK_Lambda;
700 }
701
702 ///
703 /// \brief Add a variable that might potentially be captured by the
704 /// lambda and therefore the enclosing lambdas.
705 ///
706 /// This is also used by enclosing lambda's to speculatively capture
707 /// variables that nested lambda's - depending on their enclosing
708 /// specialization - might need to capture.
709 /// Consider:
710 /// void f(int, int); <-- don't capture
711 /// void f(const int&, double); <-- capture
712 /// void foo() {
713 /// const int x = 10;
714 /// auto L = [=](auto a) { // capture 'x'
715 /// return [=](auto b) {
716 /// f(x, a); // we may or may not need to capture 'x'
717 /// };
718 /// };
719 /// }
addPotentialCapture(Expr * VarExpr)720 void addPotentialCapture(Expr *VarExpr) {
721 assert(isa<DeclRefExpr>(VarExpr) || isa<MemberExpr>(VarExpr));
722 PotentiallyCapturingExprs.push_back(VarExpr);
723 }
724
addPotentialThisCapture(SourceLocation Loc)725 void addPotentialThisCapture(SourceLocation Loc) {
726 PotentialThisCaptureLocation = Loc;
727 }
hasPotentialThisCapture()728 bool hasPotentialThisCapture() const {
729 return PotentialThisCaptureLocation.isValid();
730 }
731
732 /// \brief Mark a variable's reference in a lambda as non-odr using.
733 ///
734 /// For generic lambdas, if a variable is named in a potentially evaluated
735 /// expression, where the enclosing full expression is dependent then we
736 /// must capture the variable (given a default capture).
737 /// This is accomplished by recording all references to variables
738 /// (DeclRefExprs or MemberExprs) within said nested lambda in its array of
739 /// PotentialCaptures. All such variables have to be captured by that lambda,
740 /// except for as described below.
741 /// If that variable is usable as a constant expression and is named in a
742 /// manner that does not involve its odr-use (e.g. undergoes
743 /// lvalue-to-rvalue conversion, or discarded) record that it is so. Upon the
744 /// act of analyzing the enclosing full expression (ActOnFinishFullExpr)
745 /// if we can determine that the full expression is not instantiation-
746 /// dependent, then we can entirely avoid its capture.
747 ///
748 /// const int n = 0;
749 /// [&] (auto x) {
750 /// (void)+n + x;
751 /// };
752 /// Interestingly, this strategy would involve a capture of n, even though
753 /// it's obviously not odr-used here, because the full-expression is
754 /// instantiation-dependent. It could be useful to avoid capturing such
755 /// variables, even when they are referred to in an instantiation-dependent
756 /// expression, if we can unambiguously determine that they shall never be
757 /// odr-used. This would involve removal of the variable-referring-expression
758 /// from the array of PotentialCaptures during the lvalue-to-rvalue
759 /// conversions. But per the working draft N3797, (post-chicago 2013) we must
760 /// capture such variables.
761 /// Before anyone is tempted to implement a strategy for not-capturing 'n',
762 /// consider the insightful warning in:
763 /// /cfe-commits/Week-of-Mon-20131104/092596.html
764 /// "The problem is that the set of captures for a lambda is part of the ABI
765 /// (since lambda layout can be made visible through inline functions and the
766 /// like), and there are no guarantees as to which cases we'll manage to build
767 /// an lvalue-to-rvalue conversion in, when parsing a template -- some
768 /// seemingly harmless change elsewhere in Sema could cause us to start or stop
769 /// building such a node. So we need a rule that anyone can implement and get
770 /// exactly the same result".
771 ///
markVariableExprAsNonODRUsed(Expr * CapturingVarExpr)772 void markVariableExprAsNonODRUsed(Expr *CapturingVarExpr) {
773 assert(isa<DeclRefExpr>(CapturingVarExpr)
774 || isa<MemberExpr>(CapturingVarExpr));
775 NonODRUsedCapturingExprs.insert(CapturingVarExpr);
776 }
isVariableExprMarkedAsNonODRUsed(Expr * CapturingVarExpr)777 bool isVariableExprMarkedAsNonODRUsed(Expr *CapturingVarExpr) const {
778 assert(isa<DeclRefExpr>(CapturingVarExpr)
779 || isa<MemberExpr>(CapturingVarExpr));
780 return NonODRUsedCapturingExprs.count(CapturingVarExpr);
781 }
removePotentialCapture(Expr * E)782 void removePotentialCapture(Expr *E) {
783 PotentiallyCapturingExprs.erase(
784 std::remove(PotentiallyCapturingExprs.begin(),
785 PotentiallyCapturingExprs.end(), E),
786 PotentiallyCapturingExprs.end());
787 }
clearPotentialCaptures()788 void clearPotentialCaptures() {
789 PotentiallyCapturingExprs.clear();
790 PotentialThisCaptureLocation = SourceLocation();
791 }
getNumPotentialVariableCaptures()792 unsigned getNumPotentialVariableCaptures() const {
793 return PotentiallyCapturingExprs.size();
794 }
795
hasPotentialCaptures()796 bool hasPotentialCaptures() const {
797 return getNumPotentialVariableCaptures() ||
798 PotentialThisCaptureLocation.isValid();
799 }
800
801 // When passed the index, returns the VarDecl and Expr associated
802 // with the index.
803 void getPotentialVariableCapture(unsigned Idx, VarDecl *&VD, Expr *&E) const;
804 };
805
WeakObjectProfileTy()806 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy()
807 : Base(nullptr, false), Property(nullptr) {}
808
809 FunctionScopeInfo::WeakObjectProfileTy
getSentinel()810 FunctionScopeInfo::WeakObjectProfileTy::getSentinel() {
811 FunctionScopeInfo::WeakObjectProfileTy Result;
812 Result.Base.setInt(true);
813 return Result;
814 }
815
816 template <typename ExprT>
recordUseOfWeak(const ExprT * E,bool IsRead)817 void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) {
818 assert(E);
819 WeakUseVector &Uses = WeakObjectUses[WeakObjectProfileTy(E)];
820 Uses.push_back(WeakUseTy(E, IsRead));
821 }
822
823 inline void
addThisCapture(bool isNested,SourceLocation Loc,QualType CaptureType,Expr * Cpy)824 CapturingScopeInfo::addThisCapture(bool isNested, SourceLocation Loc,
825 QualType CaptureType, Expr *Cpy) {
826 Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, CaptureType,
827 Cpy));
828 CXXThisCaptureIndex = Captures.size();
829
830 if (LambdaScopeInfo *LSI = dyn_cast<LambdaScopeInfo>(this))
831 LSI->ArrayIndexStarts.push_back(LSI->ArrayIndexVars.size());
832 }
833
834 } // end namespace sema
835 } // end namespace clang
836
837 #endif
838