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/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" 28 #include <algorithm> 29 30 namespace clang { 31 32 class Decl; 33 class BlockDecl; 34 class CapturedDecl; 35 class CXXMethodDecl; 36 class FieldDecl; 37 class ObjCPropertyDecl; 38 class IdentifierInfo; 39 class ImplicitParamDecl; 40 class LabelDecl; 41 class ReturnStmt; 42 class Scope; 43 class SwitchStmt; 44 class TemplateTypeParmDecl; 45 class TemplateParameterList; 46 class VarDecl; 47 class ObjCIvarRefExpr; 48 class ObjCPropertyRefExpr; 49 class ObjCMessageExpr; 50 51 namespace sema { 52 53 /// \brief Contains information about the compound statement currently being 54 /// parsed. 55 class CompoundScopeInfo { 56 public: 57 CompoundScopeInfo() 58 : HasEmptyLoopBodies(false) { } 59 60 /// \brief Whether this compound stamement contains `for' or `while' loops 61 /// with empty bodies. 62 bool HasEmptyLoopBodies; 63 64 void setHasEmptyLoopBodies() { 65 HasEmptyLoopBodies = true; 66 } 67 }; 68 69 class PossiblyUnreachableDiag { 70 public: 71 PartialDiagnostic PD; 72 SourceLocation Loc; 73 const Stmt *stmt; 74 75 PossiblyUnreachableDiag(const PartialDiagnostic &PD, SourceLocation Loc, 76 const Stmt *stmt) 77 : PD(PD), Loc(Loc), stmt(stmt) {} 78 }; 79 80 /// \brief Retains information about a function, method, or block that is 81 /// currently being parsed. 82 class FunctionScopeInfo { 83 protected: 84 enum ScopeKind { 85 SK_Function, 86 SK_Block, 87 SK_Lambda, 88 SK_CapturedRegion 89 }; 90 91 public: 92 /// \brief What kind of scope we are describing. 93 /// 94 ScopeKind Kind : 3; 95 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; 99 100 /// \brief Whether this function contains any switches or direct gotos. 101 bool HasBranchIntoScope : 1; 102 103 /// \brief Whether this function contains any indirect gotos. 104 bool HasIndirectGoto : 1; 105 106 /// \brief Whether a statement was dropped because it was invalid. 107 bool HasDroppedStmt : 1; 108 109 /// \brief True if current scope is for OpenMP declare reduction combiner. 110 bool HasOMPDeclareReductionCombiner : 1; 111 112 /// \brief Whether there is a fallthrough statement in this function. 113 bool HasFallthroughStmt : 1; 114 115 /// \brief Whether we make reference to a declaration that could be 116 /// unavailable. 117 bool HasPotentialAvailabilityViolations : 1; 118 119 /// 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; 123 124 /// 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 128 /// the super class. 129 bool ObjCWarnForNoDesignatedInitChain : 1; 130 131 /// 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; 138 139 /// \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; 142 143 /// \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; 146 147 /// First coroutine statement in the current function. 148 /// (ex co_return, co_await, co_yield) 149 SourceLocation FirstCoroutineStmtLoc; 150 151 /// First 'return' statement in the current function. 152 SourceLocation FirstReturnLoc; 153 154 /// First C++ 'try' statement in the current function. 155 SourceLocation FirstCXXTryLoc; 156 157 /// First SEH '__try' statement in the current function. 158 SourceLocation FirstSEHTryLoc; 159 160 /// \brief Used to determine if errors occurred in this function or block. 161 DiagnosticErrorTrap ErrorTrap; 162 163 /// SwitchStack - This is the current set of active switch statements in the 164 /// block. 165 SmallVector<SwitchStmt*, 8> SwitchStack; 166 167 /// \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; 171 172 /// \brief The promise object for this coroutine, if any. 173 VarDecl *CoroutinePromise = nullptr; 174 175 /// \brief The initial and final coroutine suspend points. 176 std::pair<Stmt *, Stmt *> CoroutineSuspends; 177 178 /// \brief The stack of currently active compound stamement scopes in the 179 /// function. 180 SmallVector<CompoundScopeInfo, 4> CompoundScopes; 181 182 /// \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; 186 187 /// \brief A list of parameters which have the nonnull attribute and are 188 /// modified in the function. 189 llvm::SmallPtrSet<const ParmVarDecl*, 8> ModifiedNonNullParams; 190 191 public: 192 /// Represents a simple identification of a weak object. 193 /// 194 /// Part of the implementation of -Wrepeated-use-of-weak. 195 /// 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": 198 /// 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) 211 /// 212 /// Objects are identified with only two Decls to make it reasonably fast to 213 /// compare them. 214 class WeakObjectProfileTy { 215 /// The base object decl, as described in the class documentation. 216 /// 217 /// The extra flag is "true" if the Base and Property are enough to uniquely 218 /// identify the object in memory. 219 /// 220 /// \sa isExactProfile() 221 typedef llvm::PointerIntPair<const NamedDecl *, 1, bool> BaseInfoTy; 222 BaseInfoTy Base; 223 224 /// The "property" decl, as described in the class documentation. 225 /// 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; 229 230 /// Used to find the proper base profile for a given base expression. 231 static BaseInfoTy getBaseInfo(const Expr *BaseE); 232 233 inline WeakObjectProfileTy(); 234 static inline WeakObjectProfileTy getSentinel(); 235 236 public: 237 WeakObjectProfileTy(const ObjCPropertyRefExpr *RE); 238 WeakObjectProfileTy(const Expr *Base, const ObjCPropertyDecl *Property); 239 WeakObjectProfileTy(const DeclRefExpr *RE); 240 WeakObjectProfileTy(const ObjCIvarRefExpr *RE); 241 242 const NamedDecl *getBase() const { return Base.getPointer(); } 243 const NamedDecl *getProperty() const { return Property; } 244 245 /// Returns true if the object base specifies a known object in memory, 246 /// rather than, say, an instance variable or property of another object. 247 /// 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. 251 /// 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(); 258 } 259 260 bool operator==(const WeakObjectProfileTy &Other) const { 261 return Base == Other.Base && Property == Other.Property; 262 } 263 264 // 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 267 // instantiated. 268 class DenseMapInfo { 269 public: 270 static inline WeakObjectProfileTy getEmptyKey() { 271 return WeakObjectProfileTy(); 272 } 273 static inline WeakObjectProfileTy getTombstoneKey() { 274 return WeakObjectProfileTy::getSentinel(); 275 } 276 277 static unsigned getHashValue(const WeakObjectProfileTy &Val) { 278 typedef std::pair<BaseInfoTy, const NamedDecl *> Pair; 279 return llvm::DenseMapInfo<Pair>::getHashValue(Pair(Val.Base, 280 Val.Property)); 281 } 282 283 static bool isEqual(const WeakObjectProfileTy &LHS, 284 const WeakObjectProfileTy &RHS) { 285 return LHS == RHS; 286 } 287 }; 288 }; 289 290 /// Represents a single use of a weak object. 291 /// 292 /// Stores both the expression and whether the access is potentially unsafe 293 /// (i.e. it could potentially be warned about). 294 /// 295 /// Part of the implementation of -Wrepeated-use-of-weak. 296 class WeakUseTy { 297 llvm::PointerIntPair<const Expr *, 1, bool> Rep; 298 public: 299 WeakUseTy(const Expr *Use, bool IsRead) : Rep(Use, IsRead) {} 300 301 const Expr *getUseExpr() const { return Rep.getPointer(); } 302 bool isUnsafe() const { return Rep.getInt(); } 303 void markSafe() { Rep.setInt(false); } 304 305 bool operator==(const WeakUseTy &Other) const { 306 return Rep == Other.Rep; 307 } 308 }; 309 310 /// Used to collect uses of a particular weak object in a function body. 311 /// 312 /// Part of the implementation of -Wrepeated-use-of-weak. 313 typedef SmallVector<WeakUseTy, 4> WeakUseVector; 314 315 /// Used to collect all uses of weak objects in a function body. 316 /// 317 /// Part of the implementation of -Wrepeated-use-of-weak. 318 typedef llvm::SmallDenseMap<WeakObjectProfileTy, WeakUseVector, 8, 319 WeakObjectProfileTy::DenseMapInfo> 320 WeakObjectUseMap; 321 322 private: 323 /// Used to collect all uses of weak objects in this function body. 324 /// 325 /// Part of the implementation of -Wrepeated-use-of-weak. 326 WeakObjectUseMap WeakObjectUses; 327 328 protected: 329 FunctionScopeInfo(const FunctionScopeInfo&) = default; 330 331 public: 332 /// Record that a weak object was accessed. 333 /// 334 /// Part of the implementation of -Wrepeated-use-of-weak. 335 template <typename ExprT> 336 inline void recordUseOfWeak(const ExprT *E, bool IsRead = true); 337 338 void recordUseOfWeak(const ObjCMessageExpr *Msg, 339 const ObjCPropertyDecl *Prop); 340 341 /// Record that a given expression is a "safe" access of a weak object (e.g. 342 /// assigning it to a strong variable.) 343 /// 344 /// Part of the implementation of -Wrepeated-use-of-weak. 345 void markSafeWeakUse(const Expr *E); 346 347 const WeakObjectUseMap &getWeakObjectUses() const { 348 return WeakObjectUses; 349 } 350 351 void setHasBranchIntoScope() { 352 HasBranchIntoScope = true; 353 } 354 355 void setHasBranchProtectedScope() { 356 HasBranchProtectedScope = true; 357 } 358 359 void setHasIndirectGoto() { 360 HasIndirectGoto = true; 361 } 362 363 void setHasDroppedStmt() { 364 HasDroppedStmt = true; 365 } 366 367 void setHasOMPDeclareReductionCombiner() { 368 HasOMPDeclareReductionCombiner = true; 369 } 370 371 void setHasFallthroughStmt() { 372 HasFallthroughStmt = true; 373 } 374 375 void setHasCXXTry(SourceLocation TryLoc) { 376 setHasBranchProtectedScope(); 377 FirstCXXTryLoc = TryLoc; 378 } 379 380 void setHasSEHTry(SourceLocation TryLoc) { 381 setHasBranchProtectedScope(); 382 FirstSEHTryLoc = TryLoc; 383 } 384 385 bool NeedsScopeChecking() const { 386 return !HasDroppedStmt && 387 (HasIndirectGoto || 388 (HasBranchProtectedScope && HasBranchIntoScope)); 389 } 390 391 bool isCoroutine() const { return !FirstCoroutineStmtLoc.isInvalid(); } 392 393 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) 399 .Case("co_await", 1) 400 .Case("co_yield", 2); 401 } 402 403 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"; 410 default: 411 llvm_unreachable("FirstCoroutineStmtKind has an invalid value"); 412 }; 413 } 414 415 void setNeedsCoroutineSuspends(bool value = true) { 416 assert((!value || CoroutineSuspends.first == nullptr) && 417 "we already have valid suspend points"); 418 NeedsCoroutineSuspends = value; 419 } 420 421 bool hasInvalidCoroutineSuspends() const { 422 return !NeedsCoroutineSuspends && CoroutineSuspends.first == nullptr; 423 } 424 425 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; 431 } 432 433 FunctionScopeInfo(DiagnosticsEngine &Diag) 434 : Kind(SK_Function), 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), 448 ErrorTrap(Diag) { } 449 450 virtual ~FunctionScopeInfo(); 451 452 /// \brief Clear out the information in this function scope, making it 453 /// suitable for reuse. 454 void Clear(); 455 }; 456 457 class CapturingScopeInfo : public FunctionScopeInfo { 458 protected: 459 CapturingScopeInfo(const CapturingScopeInfo&) = default; 460 461 public: 462 enum ImplicitCaptureStyle { 463 ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block, 464 ImpCap_CapturedRegion 465 }; 466 467 ImplicitCaptureStyle ImpCaptureStyle; 468 469 class Capture { 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 473 // sense at all). 474 // 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. 483 enum CaptureKind { 484 Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_VLA 485 }; 486 enum { 487 IsNestedCapture = 0x1, 488 IsThisCaptured = 0x2 489 }; 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; 498 499 /// \brief The source location at which the first capture occurred. 500 SourceLocation Loc; 501 502 /// \brief The location of the ellipsis that expands a parameter pack. 503 SourceLocation EllipsisLoc; 504 505 /// \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; 508 509 /// \brief Whether an explicit capture has been odr-used in the body of the 510 /// lambda. 511 bool ODRUsed; 512 513 /// \brief Whether an explicit capture has been non-odr-used in the body of 514 /// the lambda. 515 bool NonODRUsed; 516 517 public: 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 524 : Cap_ByCopy), 525 Loc(Loc), EllipsisLoc(EllipsisLoc), CaptureType(CaptureType), 526 ODRUsed(false), NonODRUsed(false) {} 527 528 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), 535 NonODRUsed(false) {} 536 537 bool isThisCapture() const { 538 return VarAndNestedAndThis.getInt() & IsThisCaptured; 539 } 540 bool isVariableCapture() const { 541 return !isThisCapture() && !isVLATypeCapture(); 542 } 543 bool isCopyCapture() const { 544 return InitExprAndCaptureKind.getInt() == Cap_ByCopy; 545 } 546 bool isReferenceCapture() const { 547 return InitExprAndCaptureKind.getInt() == Cap_ByRef; 548 } 549 bool isBlockCapture() const { 550 return InitExprAndCaptureKind.getInt() == Cap_Block; 551 } 552 bool isVLATypeCapture() const { 553 return InitExprAndCaptureKind.getInt() == Cap_VLA; 554 } 555 bool isNested() const { 556 return VarAndNestedAndThis.getInt() & IsNestedCapture; 557 } 558 bool isODRUsed() const { return ODRUsed; } 559 bool isNonODRUsed() const { return NonODRUsed; } 560 void markUsed(bool IsODRUse) { (IsODRUse ? ODRUsed : NonODRUsed) = true; } 561 562 VarDecl *getVariable() const { 563 return VarAndNestedAndThis.getPointer(); 564 } 565 566 /// \brief Retrieve the location at which this variable was captured. 567 SourceLocation getLocation() const { return Loc; } 568 569 /// \brief Retrieve the source location of the ellipsis, whose presence 570 /// indicates that the capture is a pack expansion. 571 SourceLocation getEllipsisLoc() const { return EllipsisLoc; } 572 573 /// \brief Retrieve the capture type for this capture, which is effectively 574 /// the type of the non-static data member in the lambda/block structure 575 /// that would store this capture. 576 QualType getCaptureType() const { 577 assert(!isThisCapture()); 578 return CaptureType; 579 } 580 581 Expr *getInitExpr() const { 582 assert(!isVLATypeCapture() && "no init expression for type capture"); 583 return static_cast<Expr *>(InitExprAndCaptureKind.getPointer()); 584 } 585 }; 586 587 CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style) 588 : FunctionScopeInfo(Diag), ImpCaptureStyle(Style), CXXThisCaptureIndex(0), 589 HasImplicitReturnType(false) 590 {} 591 592 /// CaptureMap - A map of captured variables to (index+1) into Captures. 593 llvm::DenseMap<VarDecl*, unsigned> CaptureMap; 594 595 /// CXXThisCaptureIndex - The (index+1) of the capture of 'this'; 596 /// zero if 'this' is not captured. 597 unsigned CXXThisCaptureIndex; 598 599 /// Captures - The captures. 600 SmallVector<Capture, 4> Captures; 601 602 /// \brief - Whether the target type of return statements in this context 603 /// is deduced (e.g. a lambda or block with omitted return type). 604 bool HasImplicitReturnType; 605 606 /// ReturnType - The target type of return statements in this context, 607 /// or null if unknown. 608 QualType ReturnType; 609 610 void addCapture(VarDecl *Var, bool isBlock, bool isByref, bool isNested, 611 SourceLocation Loc, SourceLocation EllipsisLoc, 612 QualType CaptureType, Expr *Cpy) { 613 Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc, 614 EllipsisLoc, CaptureType, Cpy)); 615 CaptureMap[Var] = Captures.size(); 616 } 617 618 void addVLATypeCapture(SourceLocation Loc, QualType CaptureType) { 619 Captures.push_back(Capture(/*Var*/ nullptr, /*isBlock*/ false, 620 /*isByref*/ false, /*isNested*/ false, Loc, 621 /*EllipsisLoc*/ SourceLocation(), CaptureType, 622 /*Cpy*/ nullptr)); 623 } 624 625 // Note, we do not need to add the type of 'this' since that is always 626 // retrievable from Sema::getCurrentThisType - and is also encoded within the 627 // type of the corresponding FieldDecl. 628 void addThisCapture(bool isNested, SourceLocation Loc, 629 Expr *Cpy, bool ByCopy); 630 631 /// \brief Determine whether the C++ 'this' is captured. 632 bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; } 633 634 /// \brief Retrieve the capture of C++ 'this', if it has been captured. 635 Capture &getCXXThisCapture() { 636 assert(isCXXThisCaptured() && "this has not been captured"); 637 return Captures[CXXThisCaptureIndex - 1]; 638 } 639 640 /// \brief Determine whether the given variable has been captured. 641 bool isCaptured(VarDecl *Var) const { 642 return CaptureMap.count(Var); 643 } 644 645 /// \brief Determine whether the given variable-array type has been captured. 646 bool isVLATypeCaptured(const VariableArrayType *VAT) const; 647 648 /// \brief Retrieve the capture of the given variable, if it has been 649 /// captured already. 650 Capture &getCapture(VarDecl *Var) { 651 assert(isCaptured(Var) && "Variable has not been captured"); 652 return Captures[CaptureMap[Var] - 1]; 653 } 654 655 const Capture &getCapture(VarDecl *Var) const { 656 llvm::DenseMap<VarDecl*, unsigned>::const_iterator Known 657 = CaptureMap.find(Var); 658 assert(Known != CaptureMap.end() && "Variable has not been captured"); 659 return Captures[Known->second - 1]; 660 } 661 662 static bool classof(const FunctionScopeInfo *FSI) { 663 return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda 664 || FSI->Kind == SK_CapturedRegion; 665 } 666 }; 667 668 /// \brief Retains information about a block that is currently being parsed. 669 class BlockScopeInfo final : public CapturingScopeInfo { 670 public: 671 BlockDecl *TheDecl; 672 673 /// TheScope - This is the scope for the block itself, which contains 674 /// arguments etc. 675 Scope *TheScope; 676 677 /// BlockType - The function type of the block, if one was given. 678 /// Its return type may be BuiltinType::Dependent. 679 QualType FunctionType; 680 681 BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block) 682 : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block), 683 TheScope(BlockScope) 684 { 685 Kind = SK_Block; 686 } 687 688 ~BlockScopeInfo() override; 689 690 static bool classof(const FunctionScopeInfo *FSI) { 691 return FSI->Kind == SK_Block; 692 } 693 }; 694 695 /// \brief Retains information about a captured region. 696 class CapturedRegionScopeInfo final : public CapturingScopeInfo { 697 public: 698 /// \brief The CapturedDecl for this statement. 699 CapturedDecl *TheCapturedDecl; 700 /// \brief The captured record type. 701 RecordDecl *TheRecordDecl; 702 /// \brief This is the enclosing scope of the captured region. 703 Scope *TheScope; 704 /// \brief The implicit parameter for the captured variables. 705 ImplicitParamDecl *ContextParam; 706 /// \brief The kind of captured region. 707 unsigned short CapRegionKind; 708 unsigned short OpenMPLevel; 709 710 CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD, 711 RecordDecl *RD, ImplicitParamDecl *Context, 712 CapturedRegionKind K, unsigned OpenMPLevel) 713 : CapturingScopeInfo(Diag, ImpCap_CapturedRegion), 714 TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S), 715 ContextParam(Context), CapRegionKind(K), OpenMPLevel(OpenMPLevel) 716 { 717 Kind = SK_CapturedRegion; 718 } 719 720 ~CapturedRegionScopeInfo() override; 721 722 /// \brief A descriptive name for the kind of captured region this is. 723 StringRef getRegionName() const { 724 switch (CapRegionKind) { 725 case CR_Default: 726 return "default captured statement"; 727 case CR_OpenMP: 728 return "OpenMP region"; 729 } 730 llvm_unreachable("Invalid captured region kind!"); 731 } 732 733 static bool classof(const FunctionScopeInfo *FSI) { 734 return FSI->Kind == SK_CapturedRegion; 735 } 736 }; 737 738 class LambdaScopeInfo final : public CapturingScopeInfo { 739 public: 740 /// \brief The class that describes the lambda. 741 CXXRecordDecl *Lambda; 742 743 /// \brief The lambda's compiler-generated \c operator(). 744 CXXMethodDecl *CallOperator; 745 746 /// \brief Source range covering the lambda introducer [...]. 747 SourceRange IntroducerRange; 748 749 /// \brief Source location of the '&' or '=' specifying the default capture 750 /// type, if any. 751 SourceLocation CaptureDefaultLoc; 752 753 /// \brief The number of captures in the \c Captures list that are 754 /// explicit captures. 755 unsigned NumExplicitCaptures; 756 757 /// \brief Whether this is a mutable lambda. 758 bool Mutable; 759 760 /// \brief Whether the (empty) parameter list is explicit. 761 bool ExplicitParams; 762 763 /// \brief Whether any of the capture expressions requires cleanups. 764 CleanupInfo Cleanup; 765 766 /// \brief Whether the lambda contains an unexpanded parameter pack. 767 bool ContainsUnexpandedParameterPack; 768 769 /// \brief If this is a generic lambda, use this as the depth of 770 /// each 'auto' parameter, during initial AST construction. 771 unsigned AutoTemplateParameterDepth; 772 773 /// \brief Store the list of the auto parameters for a generic lambda. 774 /// If this is a generic lambda, store the list of the auto 775 /// parameters converted into TemplateTypeParmDecls into a vector 776 /// that can be used to construct the generic lambda's template 777 /// parameter list, during initial AST construction. 778 SmallVector<TemplateTypeParmDecl*, 4> AutoTemplateParams; 779 780 /// If this is a generic lambda, and the template parameter 781 /// list has been created (from the AutoTemplateParams) then 782 /// store a reference to it (cache it to avoid reconstructing it). 783 TemplateParameterList *GLTemplateParameterList; 784 785 /// \brief Contains all variable-referring-expressions (i.e. DeclRefExprs 786 /// or MemberExprs) that refer to local variables in a generic lambda 787 /// or a lambda in a potentially-evaluated-if-used context. 788 /// 789 /// Potentially capturable variables of a nested lambda that might need 790 /// to be captured by the lambda are housed here. 791 /// This is specifically useful for generic lambdas or 792 /// lambdas within a a potentially evaluated-if-used context. 793 /// If an enclosing variable is named in an expression of a lambda nested 794 /// within a generic lambda, we don't always know know whether the variable 795 /// will truly be odr-used (i.e. need to be captured) by that nested lambda, 796 /// until its instantiation. But we still need to capture it in the 797 /// enclosing lambda if all intervening lambdas can capture the variable. 798 799 llvm::SmallVector<Expr*, 4> PotentiallyCapturingExprs; 800 801 /// \brief Contains all variable-referring-expressions that refer 802 /// to local variables that are usable as constant expressions and 803 /// do not involve an odr-use (they may still need to be captured 804 /// if the enclosing full-expression is instantiation dependent). 805 llvm::SmallSet<Expr *, 8> NonODRUsedCapturingExprs; 806 807 /// Contains all of the variables defined in this lambda that shadow variables 808 /// that were defined in parent contexts. Used to avoid warnings when the 809 /// shadowed variables are uncaptured by this lambda. 810 struct ShadowedOuterDecl { 811 const VarDecl *VD; 812 const VarDecl *ShadowedDecl; 813 }; 814 llvm::SmallVector<ShadowedOuterDecl, 4> ShadowingDecls; 815 816 SourceLocation PotentialThisCaptureLocation; 817 818 LambdaScopeInfo(DiagnosticsEngine &Diag) 819 : CapturingScopeInfo(Diag, ImpCap_None), Lambda(nullptr), 820 CallOperator(nullptr), NumExplicitCaptures(0), Mutable(false), 821 ExplicitParams(false), Cleanup{}, 822 ContainsUnexpandedParameterPack(false), AutoTemplateParameterDepth(0), 823 GLTemplateParameterList(nullptr) { 824 Kind = SK_Lambda; 825 } 826 827 /// \brief Note when all explicit captures have been added. 828 void finishedExplicitCaptures() { 829 NumExplicitCaptures = Captures.size(); 830 } 831 832 static bool classof(const FunctionScopeInfo *FSI) { 833 return FSI->Kind == SK_Lambda; 834 } 835 836 /// Is this scope known to be for a generic lambda? (This will be false until 837 /// we parse the first 'auto'-typed parameter. 838 bool isGenericLambda() const { 839 return !AutoTemplateParams.empty() || GLTemplateParameterList; 840 } 841 842 /// 843 /// \brief Add a variable that might potentially be captured by the 844 /// lambda and therefore the enclosing lambdas. 845 /// 846 /// This is also used by enclosing lambda's to speculatively capture 847 /// variables that nested lambda's - depending on their enclosing 848 /// specialization - might need to capture. 849 /// Consider: 850 /// void f(int, int); <-- don't capture 851 /// void f(const int&, double); <-- capture 852 /// void foo() { 853 /// const int x = 10; 854 /// auto L = [=](auto a) { // capture 'x' 855 /// return [=](auto b) { 856 /// f(x, a); // we may or may not need to capture 'x' 857 /// }; 858 /// }; 859 /// } 860 void addPotentialCapture(Expr *VarExpr) { 861 assert(isa<DeclRefExpr>(VarExpr) || isa<MemberExpr>(VarExpr)); 862 PotentiallyCapturingExprs.push_back(VarExpr); 863 } 864 865 void addPotentialThisCapture(SourceLocation Loc) { 866 PotentialThisCaptureLocation = Loc; 867 } 868 bool hasPotentialThisCapture() const { 869 return PotentialThisCaptureLocation.isValid(); 870 } 871 872 /// \brief Mark a variable's reference in a lambda as non-odr using. 873 /// 874 /// For generic lambdas, if a variable is named in a potentially evaluated 875 /// expression, where the enclosing full expression is dependent then we 876 /// must capture the variable (given a default capture). 877 /// This is accomplished by recording all references to variables 878 /// (DeclRefExprs or MemberExprs) within said nested lambda in its array of 879 /// PotentialCaptures. All such variables have to be captured by that lambda, 880 /// except for as described below. 881 /// If that variable is usable as a constant expression and is named in a 882 /// manner that does not involve its odr-use (e.g. undergoes 883 /// lvalue-to-rvalue conversion, or discarded) record that it is so. Upon the 884 /// act of analyzing the enclosing full expression (ActOnFinishFullExpr) 885 /// if we can determine that the full expression is not instantiation- 886 /// dependent, then we can entirely avoid its capture. 887 /// 888 /// const int n = 0; 889 /// [&] (auto x) { 890 /// (void)+n + x; 891 /// }; 892 /// Interestingly, this strategy would involve a capture of n, even though 893 /// it's obviously not odr-used here, because the full-expression is 894 /// instantiation-dependent. It could be useful to avoid capturing such 895 /// variables, even when they are referred to in an instantiation-dependent 896 /// expression, if we can unambiguously determine that they shall never be 897 /// odr-used. This would involve removal of the variable-referring-expression 898 /// from the array of PotentialCaptures during the lvalue-to-rvalue 899 /// conversions. But per the working draft N3797, (post-chicago 2013) we must 900 /// capture such variables. 901 /// Before anyone is tempted to implement a strategy for not-capturing 'n', 902 /// consider the insightful warning in: 903 /// /cfe-commits/Week-of-Mon-20131104/092596.html 904 /// "The problem is that the set of captures for a lambda is part of the ABI 905 /// (since lambda layout can be made visible through inline functions and the 906 /// like), and there are no guarantees as to which cases we'll manage to build 907 /// an lvalue-to-rvalue conversion in, when parsing a template -- some 908 /// seemingly harmless change elsewhere in Sema could cause us to start or stop 909 /// building such a node. So we need a rule that anyone can implement and get 910 /// exactly the same result". 911 /// 912 void markVariableExprAsNonODRUsed(Expr *CapturingVarExpr) { 913 assert(isa<DeclRefExpr>(CapturingVarExpr) 914 || isa<MemberExpr>(CapturingVarExpr)); 915 NonODRUsedCapturingExprs.insert(CapturingVarExpr); 916 } 917 bool isVariableExprMarkedAsNonODRUsed(Expr *CapturingVarExpr) const { 918 assert(isa<DeclRefExpr>(CapturingVarExpr) 919 || isa<MemberExpr>(CapturingVarExpr)); 920 return NonODRUsedCapturingExprs.count(CapturingVarExpr); 921 } 922 void removePotentialCapture(Expr *E) { 923 PotentiallyCapturingExprs.erase( 924 std::remove(PotentiallyCapturingExprs.begin(), 925 PotentiallyCapturingExprs.end(), E), 926 PotentiallyCapturingExprs.end()); 927 } 928 void clearPotentialCaptures() { 929 PotentiallyCapturingExprs.clear(); 930 PotentialThisCaptureLocation = SourceLocation(); 931 } 932 unsigned getNumPotentialVariableCaptures() const { 933 return PotentiallyCapturingExprs.size(); 934 } 935 936 bool hasPotentialCaptures() const { 937 return getNumPotentialVariableCaptures() || 938 PotentialThisCaptureLocation.isValid(); 939 } 940 941 // When passed the index, returns the VarDecl and Expr associated 942 // with the index. 943 void getPotentialVariableCapture(unsigned Idx, VarDecl *&VD, Expr *&E) const; 944 }; 945 946 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy() 947 : Base(nullptr, false), Property(nullptr) {} 948 949 FunctionScopeInfo::WeakObjectProfileTy 950 FunctionScopeInfo::WeakObjectProfileTy::getSentinel() { 951 FunctionScopeInfo::WeakObjectProfileTy Result; 952 Result.Base.setInt(true); 953 return Result; 954 } 955 956 template <typename ExprT> 957 void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) { 958 assert(E); 959 WeakUseVector &Uses = WeakObjectUses[WeakObjectProfileTy(E)]; 960 Uses.push_back(WeakUseTy(E, IsRead)); 961 } 962 963 inline void 964 CapturingScopeInfo::addThisCapture(bool isNested, SourceLocation Loc, 965 Expr *Cpy, 966 const bool ByCopy) { 967 Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, QualType(), 968 Cpy, ByCopy)); 969 CXXThisCaptureIndex = Captures.size(); 970 } 971 972 } // end namespace sema 973 } // end namespace clang 974 975 #endif 976