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 void setFirstCoroutineStmt(SourceLocation Loc, StringRef Keyword) { 392 assert(FirstCoroutineStmtLoc.isInvalid() && 393 "first coroutine statement location already set"); 394 FirstCoroutineStmtLoc = Loc; 395 FirstCoroutineStmtKind = llvm::StringSwitch<unsigned char>(Keyword) 396 .Case("co_return", 0) 397 .Case("co_await", 1) 398 .Case("co_yield", 2); 399 } 400 401 StringRef getFirstCoroutineStmtKeyword() const { 402 assert(FirstCoroutineStmtLoc.isValid() 403 && "no coroutine statement available"); 404 switch (FirstCoroutineStmtKind) { 405 case 0: return "co_return"; 406 case 1: return "co_await"; 407 case 2: return "co_yield"; 408 default: 409 llvm_unreachable("FirstCoroutineStmtKind has an invalid value"); 410 }; 411 } 412 413 void setNeedsCoroutineSuspends(bool value = true) { 414 assert((!value || CoroutineSuspends.first == nullptr) && 415 "we already have valid suspend points"); 416 NeedsCoroutineSuspends = value; 417 } 418 419 bool hasInvalidCoroutineSuspends() const { 420 return !NeedsCoroutineSuspends && CoroutineSuspends.first == nullptr; 421 } 422 423 void setCoroutineSuspends(Stmt *Initial, Stmt *Final) { 424 assert(Initial && Final && "suspend points cannot be null"); 425 assert(CoroutineSuspends.first == nullptr && "suspend points already set"); 426 NeedsCoroutineSuspends = false; 427 CoroutineSuspends.first = Initial; 428 CoroutineSuspends.second = Final; 429 } 430 431 FunctionScopeInfo(DiagnosticsEngine &Diag) 432 : Kind(SK_Function), 433 HasBranchProtectedScope(false), 434 HasBranchIntoScope(false), 435 HasIndirectGoto(false), 436 HasDroppedStmt(false), 437 HasOMPDeclareReductionCombiner(false), 438 HasFallthroughStmt(false), 439 HasPotentialAvailabilityViolations(false), 440 ObjCShouldCallSuper(false), 441 ObjCIsDesignatedInit(false), 442 ObjCWarnForNoDesignatedInitChain(false), 443 ObjCIsSecondaryInit(false), 444 ObjCWarnForNoInitDelegation(false), 445 NeedsCoroutineSuspends(true), 446 ErrorTrap(Diag) { } 447 448 virtual ~FunctionScopeInfo(); 449 450 /// \brief Clear out the information in this function scope, making it 451 /// suitable for reuse. 452 void Clear(); 453 }; 454 455 class CapturingScopeInfo : public FunctionScopeInfo { 456 protected: 457 CapturingScopeInfo(const CapturingScopeInfo&) = default; 458 459 public: 460 enum ImplicitCaptureStyle { 461 ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block, 462 ImpCap_CapturedRegion 463 }; 464 465 ImplicitCaptureStyle ImpCaptureStyle; 466 467 class Capture { 468 // There are three categories of capture: capturing 'this', capturing 469 // local variables, and C++1y initialized captures (which can have an 470 // arbitrary initializer, and don't really capture in the traditional 471 // sense at all). 472 // 473 // There are three ways to capture a local variable: 474 // - capture by copy in the C++11 sense, 475 // - capture by reference in the C++11 sense, and 476 // - __block capture. 477 // Lambdas explicitly specify capture by copy or capture by reference. 478 // For blocks, __block capture applies to variables with that annotation, 479 // variables of reference type are captured by reference, and other 480 // variables are captured by copy. 481 enum CaptureKind { 482 Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_VLA 483 }; 484 enum { 485 IsNestedCapture = 0x1, 486 IsThisCaptured = 0x2 487 }; 488 /// The variable being captured (if we are not capturing 'this') and whether 489 /// this is a nested capture, and whether we are capturing 'this' 490 llvm::PointerIntPair<VarDecl*, 2> VarAndNestedAndThis; 491 /// Expression to initialize a field of the given type, and the kind of 492 /// capture (if this is a capture and not an init-capture). The expression 493 /// is only required if we are capturing ByVal and the variable's type has 494 /// a non-trivial copy constructor. 495 llvm::PointerIntPair<void *, 2, CaptureKind> InitExprAndCaptureKind; 496 497 /// \brief The source location at which the first capture occurred. 498 SourceLocation Loc; 499 500 /// \brief The location of the ellipsis that expands a parameter pack. 501 SourceLocation EllipsisLoc; 502 503 /// \brief The type as it was captured, which is in effect the type of the 504 /// non-static data member that would hold the capture. 505 QualType CaptureType; 506 507 /// \brief Whether an explicit capture has been odr-used in the body of the 508 /// lambda. 509 bool ODRUsed; 510 511 /// \brief Whether an explicit capture has been non-odr-used in the body of 512 /// the lambda. 513 bool NonODRUsed; 514 515 public: 516 Capture(VarDecl *Var, bool Block, bool ByRef, bool IsNested, 517 SourceLocation Loc, SourceLocation EllipsisLoc, 518 QualType CaptureType, Expr *Cpy) 519 : VarAndNestedAndThis(Var, IsNested ? IsNestedCapture : 0), 520 InitExprAndCaptureKind( 521 Cpy, !Var ? Cap_VLA : Block ? Cap_Block : ByRef ? Cap_ByRef 522 : Cap_ByCopy), 523 Loc(Loc), EllipsisLoc(EllipsisLoc), CaptureType(CaptureType), 524 ODRUsed(false), NonODRUsed(false) {} 525 526 enum IsThisCapture { ThisCapture }; 527 Capture(IsThisCapture, bool IsNested, SourceLocation Loc, 528 QualType CaptureType, Expr *Cpy, const bool ByCopy) 529 : VarAndNestedAndThis( 530 nullptr, (IsThisCaptured | (IsNested ? IsNestedCapture : 0))), 531 InitExprAndCaptureKind(Cpy, ByCopy ? Cap_ByCopy : Cap_ByRef), 532 Loc(Loc), EllipsisLoc(), CaptureType(CaptureType), ODRUsed(false), 533 NonODRUsed(false) {} 534 535 bool isThisCapture() const { 536 return VarAndNestedAndThis.getInt() & IsThisCaptured; 537 } 538 bool isVariableCapture() const { 539 return !isThisCapture() && !isVLATypeCapture(); 540 } 541 bool isCopyCapture() const { 542 return InitExprAndCaptureKind.getInt() == Cap_ByCopy; 543 } 544 bool isReferenceCapture() const { 545 return InitExprAndCaptureKind.getInt() == Cap_ByRef; 546 } 547 bool isBlockCapture() const { 548 return InitExprAndCaptureKind.getInt() == Cap_Block; 549 } 550 bool isVLATypeCapture() const { 551 return InitExprAndCaptureKind.getInt() == Cap_VLA; 552 } 553 bool isNested() const { 554 return VarAndNestedAndThis.getInt() & IsNestedCapture; 555 } 556 bool isODRUsed() const { return ODRUsed; } 557 bool isNonODRUsed() const { return NonODRUsed; } 558 void markUsed(bool IsODRUse) { (IsODRUse ? ODRUsed : NonODRUsed) = true; } 559 560 VarDecl *getVariable() const { 561 return VarAndNestedAndThis.getPointer(); 562 } 563 564 /// \brief Retrieve the location at which this variable was captured. 565 SourceLocation getLocation() const { return Loc; } 566 567 /// \brief Retrieve the source location of the ellipsis, whose presence 568 /// indicates that the capture is a pack expansion. 569 SourceLocation getEllipsisLoc() const { return EllipsisLoc; } 570 571 /// \brief Retrieve the capture type for this capture, which is effectively 572 /// the type of the non-static data member in the lambda/block structure 573 /// that would store this capture. 574 QualType getCaptureType() const { 575 assert(!isThisCapture()); 576 return CaptureType; 577 } 578 579 Expr *getInitExpr() const { 580 assert(!isVLATypeCapture() && "no init expression for type capture"); 581 return static_cast<Expr *>(InitExprAndCaptureKind.getPointer()); 582 } 583 }; 584 585 CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style) 586 : FunctionScopeInfo(Diag), ImpCaptureStyle(Style), CXXThisCaptureIndex(0), 587 HasImplicitReturnType(false) 588 {} 589 590 /// CaptureMap - A map of captured variables to (index+1) into Captures. 591 llvm::DenseMap<VarDecl*, unsigned> CaptureMap; 592 593 /// CXXThisCaptureIndex - The (index+1) of the capture of 'this'; 594 /// zero if 'this' is not captured. 595 unsigned CXXThisCaptureIndex; 596 597 /// Captures - The captures. 598 SmallVector<Capture, 4> Captures; 599 600 /// \brief - Whether the target type of return statements in this context 601 /// is deduced (e.g. a lambda or block with omitted return type). 602 bool HasImplicitReturnType; 603 604 /// ReturnType - The target type of return statements in this context, 605 /// or null if unknown. 606 QualType ReturnType; 607 608 void addCapture(VarDecl *Var, bool isBlock, bool isByref, bool isNested, 609 SourceLocation Loc, SourceLocation EllipsisLoc, 610 QualType CaptureType, Expr *Cpy) { 611 Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc, 612 EllipsisLoc, CaptureType, Cpy)); 613 CaptureMap[Var] = Captures.size(); 614 } 615 616 void addVLATypeCapture(SourceLocation Loc, QualType CaptureType) { 617 Captures.push_back(Capture(/*Var*/ nullptr, /*isBlock*/ false, 618 /*isByref*/ false, /*isNested*/ false, Loc, 619 /*EllipsisLoc*/ SourceLocation(), CaptureType, 620 /*Cpy*/ nullptr)); 621 } 622 623 // Note, we do not need to add the type of 'this' since that is always 624 // retrievable from Sema::getCurrentThisType - and is also encoded within the 625 // type of the corresponding FieldDecl. 626 void addThisCapture(bool isNested, SourceLocation Loc, 627 Expr *Cpy, bool ByCopy); 628 629 /// \brief Determine whether the C++ 'this' is captured. 630 bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; } 631 632 /// \brief Retrieve the capture of C++ 'this', if it has been captured. 633 Capture &getCXXThisCapture() { 634 assert(isCXXThisCaptured() && "this has not been captured"); 635 return Captures[CXXThisCaptureIndex - 1]; 636 } 637 638 /// \brief Determine whether the given variable has been captured. 639 bool isCaptured(VarDecl *Var) const { 640 return CaptureMap.count(Var); 641 } 642 643 /// \brief Determine whether the given variable-array type has been captured. 644 bool isVLATypeCaptured(const VariableArrayType *VAT) const; 645 646 /// \brief Retrieve the capture of the given variable, if it has been 647 /// captured already. 648 Capture &getCapture(VarDecl *Var) { 649 assert(isCaptured(Var) && "Variable has not been captured"); 650 return Captures[CaptureMap[Var] - 1]; 651 } 652 653 const Capture &getCapture(VarDecl *Var) const { 654 llvm::DenseMap<VarDecl*, unsigned>::const_iterator Known 655 = CaptureMap.find(Var); 656 assert(Known != CaptureMap.end() && "Variable has not been captured"); 657 return Captures[Known->second - 1]; 658 } 659 660 static bool classof(const FunctionScopeInfo *FSI) { 661 return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda 662 || FSI->Kind == SK_CapturedRegion; 663 } 664 }; 665 666 /// \brief Retains information about a block that is currently being parsed. 667 class BlockScopeInfo final : public CapturingScopeInfo { 668 public: 669 BlockDecl *TheDecl; 670 671 /// TheScope - This is the scope for the block itself, which contains 672 /// arguments etc. 673 Scope *TheScope; 674 675 /// BlockType - The function type of the block, if one was given. 676 /// Its return type may be BuiltinType::Dependent. 677 QualType FunctionType; 678 679 BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block) 680 : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block), 681 TheScope(BlockScope) 682 { 683 Kind = SK_Block; 684 } 685 686 ~BlockScopeInfo() override; 687 688 static bool classof(const FunctionScopeInfo *FSI) { 689 return FSI->Kind == SK_Block; 690 } 691 }; 692 693 /// \brief Retains information about a captured region. 694 class CapturedRegionScopeInfo final : public CapturingScopeInfo { 695 public: 696 /// \brief The CapturedDecl for this statement. 697 CapturedDecl *TheCapturedDecl; 698 /// \brief The captured record type. 699 RecordDecl *TheRecordDecl; 700 /// \brief This is the enclosing scope of the captured region. 701 Scope *TheScope; 702 /// \brief The implicit parameter for the captured variables. 703 ImplicitParamDecl *ContextParam; 704 /// \brief The kind of captured region. 705 unsigned short CapRegionKind; 706 unsigned short OpenMPLevel; 707 708 CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD, 709 RecordDecl *RD, ImplicitParamDecl *Context, 710 CapturedRegionKind K, unsigned OpenMPLevel) 711 : CapturingScopeInfo(Diag, ImpCap_CapturedRegion), 712 TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S), 713 ContextParam(Context), CapRegionKind(K), OpenMPLevel(OpenMPLevel) 714 { 715 Kind = SK_CapturedRegion; 716 } 717 718 ~CapturedRegionScopeInfo() override; 719 720 /// \brief A descriptive name for the kind of captured region this is. 721 StringRef getRegionName() const { 722 switch (CapRegionKind) { 723 case CR_Default: 724 return "default captured statement"; 725 case CR_OpenMP: 726 return "OpenMP region"; 727 } 728 llvm_unreachable("Invalid captured region kind!"); 729 } 730 731 static bool classof(const FunctionScopeInfo *FSI) { 732 return FSI->Kind == SK_CapturedRegion; 733 } 734 }; 735 736 class LambdaScopeInfo final : public CapturingScopeInfo { 737 public: 738 /// \brief The class that describes the lambda. 739 CXXRecordDecl *Lambda; 740 741 /// \brief The lambda's compiler-generated \c operator(). 742 CXXMethodDecl *CallOperator; 743 744 /// \brief Source range covering the lambda introducer [...]. 745 SourceRange IntroducerRange; 746 747 /// \brief Source location of the '&' or '=' specifying the default capture 748 /// type, if any. 749 SourceLocation CaptureDefaultLoc; 750 751 /// \brief The number of captures in the \c Captures list that are 752 /// explicit captures. 753 unsigned NumExplicitCaptures; 754 755 /// \brief Whether this is a mutable lambda. 756 bool Mutable; 757 758 /// \brief Whether the (empty) parameter list is explicit. 759 bool ExplicitParams; 760 761 /// \brief Whether any of the capture expressions requires cleanups. 762 CleanupInfo Cleanup; 763 764 /// \brief Whether the lambda contains an unexpanded parameter pack. 765 bool ContainsUnexpandedParameterPack; 766 767 /// \brief If this is a generic lambda, use this as the depth of 768 /// each 'auto' parameter, during initial AST construction. 769 unsigned AutoTemplateParameterDepth; 770 771 /// \brief Store the list of the auto parameters for a generic lambda. 772 /// If this is a generic lambda, store the list of the auto 773 /// parameters converted into TemplateTypeParmDecls into a vector 774 /// that can be used to construct the generic lambda's template 775 /// parameter list, during initial AST construction. 776 SmallVector<TemplateTypeParmDecl*, 4> AutoTemplateParams; 777 778 /// If this is a generic lambda, and the template parameter 779 /// list has been created (from the AutoTemplateParams) then 780 /// store a reference to it (cache it to avoid reconstructing it). 781 TemplateParameterList *GLTemplateParameterList; 782 783 /// \brief Contains all variable-referring-expressions (i.e. DeclRefExprs 784 /// or MemberExprs) that refer to local variables in a generic lambda 785 /// or a lambda in a potentially-evaluated-if-used context. 786 /// 787 /// Potentially capturable variables of a nested lambda that might need 788 /// to be captured by the lambda are housed here. 789 /// This is specifically useful for generic lambdas or 790 /// lambdas within a a potentially evaluated-if-used context. 791 /// If an enclosing variable is named in an expression of a lambda nested 792 /// within a generic lambda, we don't always know know whether the variable 793 /// will truly be odr-used (i.e. need to be captured) by that nested lambda, 794 /// until its instantiation. But we still need to capture it in the 795 /// enclosing lambda if all intervening lambdas can capture the variable. 796 797 llvm::SmallVector<Expr*, 4> PotentiallyCapturingExprs; 798 799 /// \brief Contains all variable-referring-expressions that refer 800 /// to local variables that are usable as constant expressions and 801 /// do not involve an odr-use (they may still need to be captured 802 /// if the enclosing full-expression is instantiation dependent). 803 llvm::SmallSet<Expr *, 8> NonODRUsedCapturingExprs; 804 805 /// Contains all of the variables defined in this lambda that shadow variables 806 /// that were defined in parent contexts. Used to avoid warnings when the 807 /// shadowed variables are uncaptured by this lambda. 808 struct ShadowedOuterDecl { 809 const VarDecl *VD; 810 const VarDecl *ShadowedDecl; 811 }; 812 llvm::SmallVector<ShadowedOuterDecl, 4> ShadowingDecls; 813 814 SourceLocation PotentialThisCaptureLocation; 815 816 LambdaScopeInfo(DiagnosticsEngine &Diag) 817 : CapturingScopeInfo(Diag, ImpCap_None), Lambda(nullptr), 818 CallOperator(nullptr), NumExplicitCaptures(0), Mutable(false), 819 ExplicitParams(false), Cleanup{}, 820 ContainsUnexpandedParameterPack(false), AutoTemplateParameterDepth(0), 821 GLTemplateParameterList(nullptr) { 822 Kind = SK_Lambda; 823 } 824 825 /// \brief Note when all explicit captures have been added. 826 void finishedExplicitCaptures() { 827 NumExplicitCaptures = Captures.size(); 828 } 829 830 static bool classof(const FunctionScopeInfo *FSI) { 831 return FSI->Kind == SK_Lambda; 832 } 833 834 /// 835 /// \brief Add a variable that might potentially be captured by the 836 /// lambda and therefore the enclosing lambdas. 837 /// 838 /// This is also used by enclosing lambda's to speculatively capture 839 /// variables that nested lambda's - depending on their enclosing 840 /// specialization - might need to capture. 841 /// Consider: 842 /// void f(int, int); <-- don't capture 843 /// void f(const int&, double); <-- capture 844 /// void foo() { 845 /// const int x = 10; 846 /// auto L = [=](auto a) { // capture 'x' 847 /// return [=](auto b) { 848 /// f(x, a); // we may or may not need to capture 'x' 849 /// }; 850 /// }; 851 /// } 852 void addPotentialCapture(Expr *VarExpr) { 853 assert(isa<DeclRefExpr>(VarExpr) || isa<MemberExpr>(VarExpr)); 854 PotentiallyCapturingExprs.push_back(VarExpr); 855 } 856 857 void addPotentialThisCapture(SourceLocation Loc) { 858 PotentialThisCaptureLocation = Loc; 859 } 860 bool hasPotentialThisCapture() const { 861 return PotentialThisCaptureLocation.isValid(); 862 } 863 864 /// \brief Mark a variable's reference in a lambda as non-odr using. 865 /// 866 /// For generic lambdas, if a variable is named in a potentially evaluated 867 /// expression, where the enclosing full expression is dependent then we 868 /// must capture the variable (given a default capture). 869 /// This is accomplished by recording all references to variables 870 /// (DeclRefExprs or MemberExprs) within said nested lambda in its array of 871 /// PotentialCaptures. All such variables have to be captured by that lambda, 872 /// except for as described below. 873 /// If that variable is usable as a constant expression and is named in a 874 /// manner that does not involve its odr-use (e.g. undergoes 875 /// lvalue-to-rvalue conversion, or discarded) record that it is so. Upon the 876 /// act of analyzing the enclosing full expression (ActOnFinishFullExpr) 877 /// if we can determine that the full expression is not instantiation- 878 /// dependent, then we can entirely avoid its capture. 879 /// 880 /// const int n = 0; 881 /// [&] (auto x) { 882 /// (void)+n + x; 883 /// }; 884 /// Interestingly, this strategy would involve a capture of n, even though 885 /// it's obviously not odr-used here, because the full-expression is 886 /// instantiation-dependent. It could be useful to avoid capturing such 887 /// variables, even when they are referred to in an instantiation-dependent 888 /// expression, if we can unambiguously determine that they shall never be 889 /// odr-used. This would involve removal of the variable-referring-expression 890 /// from the array of PotentialCaptures during the lvalue-to-rvalue 891 /// conversions. But per the working draft N3797, (post-chicago 2013) we must 892 /// capture such variables. 893 /// Before anyone is tempted to implement a strategy for not-capturing 'n', 894 /// consider the insightful warning in: 895 /// /cfe-commits/Week-of-Mon-20131104/092596.html 896 /// "The problem is that the set of captures for a lambda is part of the ABI 897 /// (since lambda layout can be made visible through inline functions and the 898 /// like), and there are no guarantees as to which cases we'll manage to build 899 /// an lvalue-to-rvalue conversion in, when parsing a template -- some 900 /// seemingly harmless change elsewhere in Sema could cause us to start or stop 901 /// building such a node. So we need a rule that anyone can implement and get 902 /// exactly the same result". 903 /// 904 void markVariableExprAsNonODRUsed(Expr *CapturingVarExpr) { 905 assert(isa<DeclRefExpr>(CapturingVarExpr) 906 || isa<MemberExpr>(CapturingVarExpr)); 907 NonODRUsedCapturingExprs.insert(CapturingVarExpr); 908 } 909 bool isVariableExprMarkedAsNonODRUsed(Expr *CapturingVarExpr) const { 910 assert(isa<DeclRefExpr>(CapturingVarExpr) 911 || isa<MemberExpr>(CapturingVarExpr)); 912 return NonODRUsedCapturingExprs.count(CapturingVarExpr); 913 } 914 void removePotentialCapture(Expr *E) { 915 PotentiallyCapturingExprs.erase( 916 std::remove(PotentiallyCapturingExprs.begin(), 917 PotentiallyCapturingExprs.end(), E), 918 PotentiallyCapturingExprs.end()); 919 } 920 void clearPotentialCaptures() { 921 PotentiallyCapturingExprs.clear(); 922 PotentialThisCaptureLocation = SourceLocation(); 923 } 924 unsigned getNumPotentialVariableCaptures() const { 925 return PotentiallyCapturingExprs.size(); 926 } 927 928 bool hasPotentialCaptures() const { 929 return getNumPotentialVariableCaptures() || 930 PotentialThisCaptureLocation.isValid(); 931 } 932 933 // When passed the index, returns the VarDecl and Expr associated 934 // with the index. 935 void getPotentialVariableCapture(unsigned Idx, VarDecl *&VD, Expr *&E) const; 936 }; 937 938 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy() 939 : Base(nullptr, false), Property(nullptr) {} 940 941 FunctionScopeInfo::WeakObjectProfileTy 942 FunctionScopeInfo::WeakObjectProfileTy::getSentinel() { 943 FunctionScopeInfo::WeakObjectProfileTy Result; 944 Result.Base.setInt(true); 945 return Result; 946 } 947 948 template <typename ExprT> 949 void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) { 950 assert(E); 951 WeakUseVector &Uses = WeakObjectUses[WeakObjectProfileTy(E)]; 952 Uses.push_back(WeakUseTy(E, IsRead)); 953 } 954 955 inline void 956 CapturingScopeInfo::addThisCapture(bool isNested, SourceLocation Loc, 957 Expr *Cpy, 958 const bool ByCopy) { 959 Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, QualType(), 960 Cpy, ByCopy)); 961 CXXThisCaptureIndex = Captures.size(); 962 } 963 964 } // end namespace sema 965 } // end namespace clang 966 967 #endif 968