1 //===- ScopeInfo.h - Information about a semantic context -------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines FunctionScopeInfo and its subclasses, which contain 10 // information about a single function, block, lambda, or method body. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_SEMA_SCOPEINFO_H 15 #define LLVM_CLANG_SEMA_SCOPEINFO_H 16 17 #include "clang/AST/Expr.h" 18 #include "clang/AST/ExprCXX.h" 19 #include "clang/AST/Type.h" 20 #include "clang/Basic/CapturedStmt.h" 21 #include "clang/Basic/LLVM.h" 22 #include "clang/Basic/PartialDiagnostic.h" 23 #include "clang/Basic/SourceLocation.h" 24 #include "clang/Sema/CleanupInfo.h" 25 #include "clang/Sema/DeclSpec.h" 26 #include "llvm/ADT/DenseMap.h" 27 #include "llvm/ADT/DenseMapInfo.h" 28 #include "llvm/ADT/MapVector.h" 29 #include "llvm/ADT/PointerIntPair.h" 30 #include "llvm/ADT/SmallPtrSet.h" 31 #include "llvm/ADT/SmallSet.h" 32 #include "llvm/ADT/SmallVector.h" 33 #include "llvm/ADT/StringRef.h" 34 #include "llvm/ADT/StringSwitch.h" 35 #include "llvm/ADT/TinyPtrVector.h" 36 #include "llvm/Support/Casting.h" 37 #include "llvm/Support/ErrorHandling.h" 38 #include <algorithm> 39 #include <cassert> 40 #include <utility> 41 42 namespace clang { 43 44 class BlockDecl; 45 class CapturedDecl; 46 class CXXMethodDecl; 47 class CXXRecordDecl; 48 class ImplicitParamDecl; 49 class NamedDecl; 50 class ObjCIvarRefExpr; 51 class ObjCMessageExpr; 52 class ObjCPropertyDecl; 53 class ObjCPropertyRefExpr; 54 class ParmVarDecl; 55 class RecordDecl; 56 class ReturnStmt; 57 class Scope; 58 class Stmt; 59 class SwitchStmt; 60 class TemplateParameterList; 61 class VarDecl; 62 63 namespace sema { 64 65 /// Contains information about the compound statement currently being 66 /// parsed. 67 class CompoundScopeInfo { 68 public: 69 /// Whether this compound stamement contains `for' or `while' loops 70 /// with empty bodies. 71 bool HasEmptyLoopBodies = false; 72 73 /// Whether this compound statement corresponds to a GNU statement 74 /// expression. 75 bool IsStmtExpr; 76 77 /// FP options at the beginning of the compound statement, prior to 78 /// any pragma. 79 FPOptions InitialFPFeatures; 80 81 CompoundScopeInfo(bool IsStmtExpr, FPOptions FPO) 82 : IsStmtExpr(IsStmtExpr), InitialFPFeatures(FPO) {} 83 84 void setHasEmptyLoopBodies() { 85 HasEmptyLoopBodies = true; 86 } 87 }; 88 89 class PossiblyUnreachableDiag { 90 public: 91 PartialDiagnostic PD; 92 SourceLocation Loc; 93 llvm::TinyPtrVector<const Stmt*> Stmts; 94 95 PossiblyUnreachableDiag(const PartialDiagnostic &PD, SourceLocation Loc, 96 ArrayRef<const Stmt *> Stmts) 97 : PD(PD), Loc(Loc), Stmts(Stmts) {} 98 }; 99 100 /// Retains information about a function, method, or block that is 101 /// currently being parsed. 102 class FunctionScopeInfo { 103 protected: 104 enum ScopeKind { 105 SK_Function, 106 SK_Block, 107 SK_Lambda, 108 SK_CapturedRegion 109 }; 110 111 public: 112 /// What kind of scope we are describing. 113 ScopeKind Kind : 3; 114 115 /// Whether this function contains a VLA, \@try, try, C++ 116 /// initializer, or anything else that can't be jumped past. 117 bool HasBranchProtectedScope : 1; 118 119 /// Whether this function contains any switches or direct gotos. 120 bool HasBranchIntoScope : 1; 121 122 /// Whether this function contains any indirect gotos. 123 bool HasIndirectGoto : 1; 124 125 /// Whether this function contains any statement marked with 126 /// \c [[clang::musttail]]. 127 bool HasMustTail : 1; 128 129 /// Whether a statement was dropped because it was invalid. 130 bool HasDroppedStmt : 1; 131 132 /// True if current scope is for OpenMP declare reduction combiner. 133 bool HasOMPDeclareReductionCombiner : 1; 134 135 /// Whether there is a fallthrough statement in this function. 136 bool HasFallthroughStmt : 1; 137 138 /// Whether this function uses constrained floating point intrinsics 139 bool UsesFPIntrin : 1; 140 141 /// Whether we make reference to a declaration that could be 142 /// unavailable. 143 bool HasPotentialAvailabilityViolations : 1; 144 145 /// A flag that is set when parsing a method that must call super's 146 /// implementation, such as \c -dealloc, \c -finalize, or any method marked 147 /// with \c __attribute__((objc_requires_super)). 148 bool ObjCShouldCallSuper : 1; 149 150 /// True when this is a method marked as a designated initializer. 151 bool ObjCIsDesignatedInit : 1; 152 153 /// This starts true for a method marked as designated initializer and will 154 /// be set to false if there is an invocation to a designated initializer of 155 /// the super class. 156 bool ObjCWarnForNoDesignatedInitChain : 1; 157 158 /// True when this is an initializer method not marked as a designated 159 /// initializer within a class that has at least one initializer marked as a 160 /// designated initializer. 161 bool ObjCIsSecondaryInit : 1; 162 163 /// This starts true for a secondary initializer method and will be set to 164 /// false if there is an invocation of an initializer on 'self'. 165 bool ObjCWarnForNoInitDelegation : 1; 166 167 /// True only when this function has not already built, or attempted 168 /// to build, the initial and final coroutine suspend points 169 bool NeedsCoroutineSuspends : 1; 170 171 /// An enumeration represeting the kind of the first coroutine statement 172 /// in the function. One of co_return, co_await, or co_yield. 173 unsigned char FirstCoroutineStmtKind : 2; 174 175 /// Whether we found an immediate-escalating expression. 176 bool FoundImmediateEscalatingExpression : 1; 177 178 /// First coroutine statement in the current function. 179 /// (ex co_return, co_await, co_yield) 180 SourceLocation FirstCoroutineStmtLoc; 181 182 /// First 'return' statement in the current function. 183 SourceLocation FirstReturnLoc; 184 185 /// First C++ 'try' or ObjC @try statement in the current function. 186 SourceLocation FirstCXXOrObjCTryLoc; 187 enum { TryLocIsCXX, TryLocIsObjC, Unknown } FirstTryType = Unknown; 188 189 /// First SEH '__try' statement in the current function. 190 SourceLocation FirstSEHTryLoc; 191 192 private: 193 /// Used to determine if errors occurred in this function or block. 194 DiagnosticErrorTrap ErrorTrap; 195 196 public: 197 /// A SwitchStmt, along with a flag indicating if its list of case statements 198 /// is incomplete (because we dropped an invalid one while parsing). 199 using SwitchInfo = llvm::PointerIntPair<SwitchStmt*, 1, bool>; 200 201 /// SwitchStack - This is the current set of active switch statements in the 202 /// block. 203 SmallVector<SwitchInfo, 8> SwitchStack; 204 205 /// The list of return statements that occur within the function or 206 /// block, if there is any chance of applying the named return value 207 /// optimization, or if we need to infer a return type. 208 SmallVector<ReturnStmt*, 4> Returns; 209 210 /// The promise object for this coroutine, if any. 211 VarDecl *CoroutinePromise = nullptr; 212 213 /// A mapping between the coroutine function parameters that were moved 214 /// to the coroutine frame, and their move statements. 215 llvm::SmallMapVector<ParmVarDecl *, Stmt *, 4> CoroutineParameterMoves; 216 217 /// The initial and final coroutine suspend points. 218 std::pair<Stmt *, Stmt *> CoroutineSuspends; 219 220 /// The stack of currently active compound stamement scopes in the 221 /// function. 222 SmallVector<CompoundScopeInfo, 4> CompoundScopes; 223 224 /// The set of blocks that are introduced in this function. 225 llvm::SmallPtrSet<const BlockDecl *, 1> Blocks; 226 227 /// The set of __block variables that are introduced in this function. 228 llvm::TinyPtrVector<VarDecl *> ByrefBlockVars; 229 230 /// A list of PartialDiagnostics created but delayed within the 231 /// current function scope. These diagnostics are vetted for reachability 232 /// prior to being emitted. 233 SmallVector<PossiblyUnreachableDiag, 4> PossiblyUnreachableDiags; 234 235 /// A list of parameters which have the nonnull attribute and are 236 /// modified in the function. 237 llvm::SmallPtrSet<const ParmVarDecl *, 8> ModifiedNonNullParams; 238 239 /// The set of GNU address of label extension "&&label". 240 llvm::SmallVector<AddrLabelExpr *, 4> AddrLabels; 241 242 public: 243 /// Represents a simple identification of a weak object. 244 /// 245 /// Part of the implementation of -Wrepeated-use-of-weak. 246 /// 247 /// This is used to determine if two weak accesses refer to the same object. 248 /// Here are some examples of how various accesses are "profiled": 249 /// 250 /// Access Expression | "Base" Decl | "Property" Decl 251 /// :---------------: | :-----------------: | :------------------------------: 252 /// self.property | self (VarDecl) | property (ObjCPropertyDecl) 253 /// self.implicitProp | self (VarDecl) | -implicitProp (ObjCMethodDecl) 254 /// self->ivar.prop | ivar (ObjCIvarDecl) | prop (ObjCPropertyDecl) 255 /// cxxObj.obj.prop | obj (FieldDecl) | prop (ObjCPropertyDecl) 256 /// [self foo].prop | 0 (unknown) | prop (ObjCPropertyDecl) 257 /// self.prop1.prop2 | prop1 (ObjCPropertyDecl) | prop2 (ObjCPropertyDecl) 258 /// MyClass.prop | MyClass (ObjCInterfaceDecl) | -prop (ObjCMethodDecl) 259 /// MyClass.foo.prop | +foo (ObjCMethodDecl) | -prop (ObjCPropertyDecl) 260 /// weakVar | 0 (known) | weakVar (VarDecl) 261 /// self->weakIvar | self (VarDecl) | weakIvar (ObjCIvarDecl) 262 /// 263 /// Objects are identified with only two Decls to make it reasonably fast to 264 /// compare them. 265 class WeakObjectProfileTy { 266 /// The base object decl, as described in the class documentation. 267 /// 268 /// The extra flag is "true" if the Base and Property are enough to uniquely 269 /// identify the object in memory. 270 /// 271 /// \sa isExactProfile() 272 using BaseInfoTy = llvm::PointerIntPair<const NamedDecl *, 1, bool>; 273 BaseInfoTy Base; 274 275 /// The "property" decl, as described in the class documentation. 276 /// 277 /// Note that this may not actually be an ObjCPropertyDecl, e.g. in the 278 /// case of "implicit" properties (regular methods accessed via dot syntax). 279 const NamedDecl *Property = nullptr; 280 281 /// Used to find the proper base profile for a given base expression. 282 static BaseInfoTy getBaseInfo(const Expr *BaseE); 283 284 inline WeakObjectProfileTy(); 285 static inline WeakObjectProfileTy getSentinel(); 286 287 public: 288 WeakObjectProfileTy(const ObjCPropertyRefExpr *RE); 289 WeakObjectProfileTy(const Expr *Base, const ObjCPropertyDecl *Property); 290 WeakObjectProfileTy(const DeclRefExpr *RE); 291 WeakObjectProfileTy(const ObjCIvarRefExpr *RE); 292 293 const NamedDecl *getBase() const { return Base.getPointer(); } 294 const NamedDecl *getProperty() const { return Property; } 295 296 /// Returns true if the object base specifies a known object in memory, 297 /// rather than, say, an instance variable or property of another object. 298 /// 299 /// Note that this ignores the effects of aliasing; that is, \c foo.bar is 300 /// considered an exact profile if \c foo is a local variable, even if 301 /// another variable \c foo2 refers to the same object as \c foo. 302 /// 303 /// For increased precision, accesses with base variables that are 304 /// properties or ivars of 'self' (e.g. self.prop1.prop2) are considered to 305 /// be exact, though this is not true for arbitrary variables 306 /// (foo.prop1.prop2). 307 bool isExactProfile() const { 308 return Base.getInt(); 309 } 310 311 bool operator==(const WeakObjectProfileTy &Other) const { 312 return Base == Other.Base && Property == Other.Property; 313 } 314 315 // For use in DenseMap. 316 // We can't specialize the usual llvm::DenseMapInfo at the end of the file 317 // because by that point the DenseMap in FunctionScopeInfo has already been 318 // instantiated. 319 class DenseMapInfo { 320 public: 321 static inline WeakObjectProfileTy getEmptyKey() { 322 return WeakObjectProfileTy(); 323 } 324 325 static inline WeakObjectProfileTy getTombstoneKey() { 326 return WeakObjectProfileTy::getSentinel(); 327 } 328 329 static unsigned getHashValue(const WeakObjectProfileTy &Val) { 330 using Pair = std::pair<BaseInfoTy, const NamedDecl *>; 331 332 return llvm::DenseMapInfo<Pair>::getHashValue(Pair(Val.Base, 333 Val.Property)); 334 } 335 336 static bool isEqual(const WeakObjectProfileTy &LHS, 337 const WeakObjectProfileTy &RHS) { 338 return LHS == RHS; 339 } 340 }; 341 }; 342 343 /// Represents a single use of a weak object. 344 /// 345 /// Stores both the expression and whether the access is potentially unsafe 346 /// (i.e. it could potentially be warned about). 347 /// 348 /// Part of the implementation of -Wrepeated-use-of-weak. 349 class WeakUseTy { 350 llvm::PointerIntPair<const Expr *, 1, bool> Rep; 351 352 public: 353 WeakUseTy(const Expr *Use, bool IsRead) : Rep(Use, IsRead) {} 354 355 const Expr *getUseExpr() const { return Rep.getPointer(); } 356 bool isUnsafe() const { return Rep.getInt(); } 357 void markSafe() { Rep.setInt(false); } 358 359 bool operator==(const WeakUseTy &Other) const { 360 return Rep == Other.Rep; 361 } 362 }; 363 364 /// Used to collect uses of a particular weak object in a function body. 365 /// 366 /// Part of the implementation of -Wrepeated-use-of-weak. 367 using WeakUseVector = SmallVector<WeakUseTy, 4>; 368 369 /// Used to collect all uses of weak objects in a function body. 370 /// 371 /// Part of the implementation of -Wrepeated-use-of-weak. 372 using WeakObjectUseMap = 373 llvm::SmallDenseMap<WeakObjectProfileTy, WeakUseVector, 8, 374 WeakObjectProfileTy::DenseMapInfo>; 375 376 private: 377 /// Used to collect all uses of weak objects in this function body. 378 /// 379 /// Part of the implementation of -Wrepeated-use-of-weak. 380 WeakObjectUseMap WeakObjectUses; 381 382 protected: 383 FunctionScopeInfo(const FunctionScopeInfo&) = default; 384 385 public: 386 FunctionScopeInfo(DiagnosticsEngine &Diag) 387 : Kind(SK_Function), HasBranchProtectedScope(false), 388 HasBranchIntoScope(false), HasIndirectGoto(false), HasMustTail(false), 389 HasDroppedStmt(false), HasOMPDeclareReductionCombiner(false), 390 HasFallthroughStmt(false), UsesFPIntrin(false), 391 HasPotentialAvailabilityViolations(false), ObjCShouldCallSuper(false), 392 ObjCIsDesignatedInit(false), ObjCWarnForNoDesignatedInitChain(false), 393 ObjCIsSecondaryInit(false), ObjCWarnForNoInitDelegation(false), 394 NeedsCoroutineSuspends(true), FoundImmediateEscalatingExpression(false), 395 ErrorTrap(Diag) {} 396 397 virtual ~FunctionScopeInfo(); 398 399 /// Determine whether an unrecoverable error has occurred within this 400 /// function. Note that this may return false even if the function body is 401 /// invalid, because the errors may be suppressed if they're caused by prior 402 /// invalid declarations. 403 /// 404 /// FIXME: Migrate the caller of this to use containsErrors() instead once 405 /// it's ready. 406 bool hasUnrecoverableErrorOccurred() const { 407 return ErrorTrap.hasUnrecoverableErrorOccurred(); 408 } 409 410 /// Record that a weak object was accessed. 411 /// 412 /// Part of the implementation of -Wrepeated-use-of-weak. 413 template <typename ExprT> 414 inline void recordUseOfWeak(const ExprT *E, bool IsRead = true); 415 416 void recordUseOfWeak(const ObjCMessageExpr *Msg, 417 const ObjCPropertyDecl *Prop); 418 419 /// Record that a given expression is a "safe" access of a weak object (e.g. 420 /// assigning it to a strong variable.) 421 /// 422 /// Part of the implementation of -Wrepeated-use-of-weak. 423 void markSafeWeakUse(const Expr *E); 424 425 const WeakObjectUseMap &getWeakObjectUses() const { 426 return WeakObjectUses; 427 } 428 429 void setHasBranchIntoScope() { 430 HasBranchIntoScope = true; 431 } 432 433 void setHasBranchProtectedScope() { 434 HasBranchProtectedScope = true; 435 } 436 437 void setHasIndirectGoto() { 438 HasIndirectGoto = true; 439 } 440 441 void setHasMustTail() { HasMustTail = true; } 442 443 void setHasDroppedStmt() { 444 HasDroppedStmt = true; 445 } 446 447 void setHasOMPDeclareReductionCombiner() { 448 HasOMPDeclareReductionCombiner = true; 449 } 450 451 void setHasFallthroughStmt() { 452 HasFallthroughStmt = true; 453 } 454 455 void setUsesFPIntrin() { 456 UsesFPIntrin = true; 457 } 458 459 void setHasCXXTry(SourceLocation TryLoc) { 460 setHasBranchProtectedScope(); 461 FirstCXXOrObjCTryLoc = TryLoc; 462 FirstTryType = TryLocIsCXX; 463 } 464 465 void setHasObjCTry(SourceLocation TryLoc) { 466 setHasBranchProtectedScope(); 467 FirstCXXOrObjCTryLoc = TryLoc; 468 FirstTryType = TryLocIsObjC; 469 } 470 471 void setHasSEHTry(SourceLocation TryLoc) { 472 setHasBranchProtectedScope(); 473 FirstSEHTryLoc = TryLoc; 474 } 475 476 bool NeedsScopeChecking() const { 477 return !HasDroppedStmt && (HasIndirectGoto || HasMustTail || 478 (HasBranchProtectedScope && HasBranchIntoScope)); 479 } 480 481 // Add a block introduced in this function. 482 void addBlock(const BlockDecl *BD) { 483 Blocks.insert(BD); 484 } 485 486 // Add a __block variable introduced in this function. 487 void addByrefBlockVar(VarDecl *VD) { 488 ByrefBlockVars.push_back(VD); 489 } 490 491 bool isCoroutine() const { return !FirstCoroutineStmtLoc.isInvalid(); } 492 493 void setFirstCoroutineStmt(SourceLocation Loc, StringRef Keyword) { 494 assert(FirstCoroutineStmtLoc.isInvalid() && 495 "first coroutine statement location already set"); 496 FirstCoroutineStmtLoc = Loc; 497 FirstCoroutineStmtKind = llvm::StringSwitch<unsigned char>(Keyword) 498 .Case("co_return", 0) 499 .Case("co_await", 1) 500 .Case("co_yield", 2); 501 } 502 503 StringRef getFirstCoroutineStmtKeyword() const { 504 assert(FirstCoroutineStmtLoc.isValid() 505 && "no coroutine statement available"); 506 switch (FirstCoroutineStmtKind) { 507 case 0: return "co_return"; 508 case 1: return "co_await"; 509 case 2: return "co_yield"; 510 default: 511 llvm_unreachable("FirstCoroutineStmtKind has an invalid value"); 512 }; 513 } 514 515 void setNeedsCoroutineSuspends(bool value = true) { 516 assert((!value || CoroutineSuspends.first == nullptr) && 517 "we already have valid suspend points"); 518 NeedsCoroutineSuspends = value; 519 } 520 521 bool hasInvalidCoroutineSuspends() const { 522 return !NeedsCoroutineSuspends && CoroutineSuspends.first == nullptr; 523 } 524 525 void setCoroutineSuspends(Stmt *Initial, Stmt *Final) { 526 assert(Initial && Final && "suspend points cannot be null"); 527 assert(CoroutineSuspends.first == nullptr && "suspend points already set"); 528 NeedsCoroutineSuspends = false; 529 CoroutineSuspends.first = Initial; 530 CoroutineSuspends.second = Final; 531 } 532 533 /// Clear out the information in this function scope, making it 534 /// suitable for reuse. 535 void Clear(); 536 537 bool isPlainFunction() const { return Kind == SK_Function; } 538 }; 539 540 class Capture { 541 // There are three categories of capture: capturing 'this', capturing 542 // local variables, and C++1y initialized captures (which can have an 543 // arbitrary initializer, and don't really capture in the traditional 544 // sense at all). 545 // 546 // There are three ways to capture a local variable: 547 // - capture by copy in the C++11 sense, 548 // - capture by reference in the C++11 sense, and 549 // - __block capture. 550 // Lambdas explicitly specify capture by copy or capture by reference. 551 // For blocks, __block capture applies to variables with that annotation, 552 // variables of reference type are captured by reference, and other 553 // variables are captured by copy. 554 enum CaptureKind { 555 Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_VLA 556 }; 557 558 union { 559 /// If Kind == Cap_VLA, the captured type. 560 const VariableArrayType *CapturedVLA; 561 562 /// Otherwise, the captured variable (if any). 563 ValueDecl *CapturedVar; 564 }; 565 566 /// The source location at which the first capture occurred. 567 SourceLocation Loc; 568 569 /// The location of the ellipsis that expands a parameter pack. 570 SourceLocation EllipsisLoc; 571 572 /// The type as it was captured, which is the type of the non-static data 573 /// member that would hold the capture. 574 QualType CaptureType; 575 576 /// The CaptureKind of this capture. 577 unsigned Kind : 2; 578 579 /// Whether this is a nested capture (a capture of an enclosing capturing 580 /// scope's capture). 581 unsigned Nested : 1; 582 583 /// Whether this is a capture of '*this'. 584 unsigned CapturesThis : 1; 585 586 /// Whether an explicit capture has been odr-used in the body of the 587 /// lambda. 588 unsigned ODRUsed : 1; 589 590 /// Whether an explicit capture has been non-odr-used in the body of 591 /// the lambda. 592 unsigned NonODRUsed : 1; 593 594 /// Whether the capture is invalid (a capture was required but the entity is 595 /// non-capturable). 596 unsigned Invalid : 1; 597 598 public: 599 Capture(ValueDecl *Var, bool Block, bool ByRef, bool IsNested, 600 SourceLocation Loc, SourceLocation EllipsisLoc, QualType CaptureType, 601 bool Invalid) 602 : CapturedVar(Var), Loc(Loc), EllipsisLoc(EllipsisLoc), 603 CaptureType(CaptureType), Kind(Block ? Cap_Block 604 : ByRef ? Cap_ByRef 605 : Cap_ByCopy), 606 Nested(IsNested), CapturesThis(false), ODRUsed(false), 607 NonODRUsed(false), Invalid(Invalid) {} 608 609 enum IsThisCapture { ThisCapture }; 610 Capture(IsThisCapture, bool IsNested, SourceLocation Loc, 611 QualType CaptureType, const bool ByCopy, bool Invalid) 612 : Loc(Loc), CaptureType(CaptureType), 613 Kind(ByCopy ? Cap_ByCopy : Cap_ByRef), Nested(IsNested), 614 CapturesThis(true), ODRUsed(false), NonODRUsed(false), 615 Invalid(Invalid) {} 616 617 enum IsVLACapture { VLACapture }; 618 Capture(IsVLACapture, const VariableArrayType *VLA, bool IsNested, 619 SourceLocation Loc, QualType CaptureType) 620 : CapturedVLA(VLA), Loc(Loc), CaptureType(CaptureType), Kind(Cap_VLA), 621 Nested(IsNested), CapturesThis(false), ODRUsed(false), 622 NonODRUsed(false), Invalid(false) {} 623 624 bool isThisCapture() const { return CapturesThis; } 625 bool isVariableCapture() const { 626 return !isThisCapture() && !isVLATypeCapture(); 627 } 628 629 bool isCopyCapture() const { return Kind == Cap_ByCopy; } 630 bool isReferenceCapture() const { return Kind == Cap_ByRef; } 631 bool isBlockCapture() const { return Kind == Cap_Block; } 632 bool isVLATypeCapture() const { return Kind == Cap_VLA; } 633 634 bool isNested() const { return Nested; } 635 636 bool isInvalid() const { return Invalid; } 637 638 /// Determine whether this capture is an init-capture. 639 bool isInitCapture() const; 640 641 bool isODRUsed() const { return ODRUsed; } 642 bool isNonODRUsed() const { return NonODRUsed; } 643 void markUsed(bool IsODRUse) { 644 if (IsODRUse) 645 ODRUsed = true; 646 else 647 NonODRUsed = true; 648 } 649 650 ValueDecl *getVariable() const { 651 assert(isVariableCapture()); 652 return CapturedVar; 653 } 654 655 const VariableArrayType *getCapturedVLAType() const { 656 assert(isVLATypeCapture()); 657 return CapturedVLA; 658 } 659 660 /// Retrieve the location at which this variable was captured. 661 SourceLocation getLocation() const { return Loc; } 662 663 /// Retrieve the source location of the ellipsis, whose presence 664 /// indicates that the capture is a pack expansion. 665 SourceLocation getEllipsisLoc() const { return EllipsisLoc; } 666 667 /// Retrieve the capture type for this capture, which is effectively 668 /// the type of the non-static data member in the lambda/block structure 669 /// that would store this capture. 670 QualType getCaptureType() const { return CaptureType; } 671 }; 672 673 class CapturingScopeInfo : public FunctionScopeInfo { 674 protected: 675 CapturingScopeInfo(const CapturingScopeInfo&) = default; 676 677 public: 678 enum ImplicitCaptureStyle { 679 ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block, 680 ImpCap_CapturedRegion 681 }; 682 683 ImplicitCaptureStyle ImpCaptureStyle; 684 685 CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style) 686 : FunctionScopeInfo(Diag), ImpCaptureStyle(Style) {} 687 688 /// CaptureMap - A map of captured variables to (index+1) into Captures. 689 llvm::DenseMap<ValueDecl *, unsigned> CaptureMap; 690 691 /// CXXThisCaptureIndex - The (index+1) of the capture of 'this'; 692 /// zero if 'this' is not captured. 693 unsigned CXXThisCaptureIndex = 0; 694 695 /// Captures - The captures. 696 SmallVector<Capture, 4> Captures; 697 698 /// - Whether the target type of return statements in this context 699 /// is deduced (e.g. a lambda or block with omitted return type). 700 bool HasImplicitReturnType = false; 701 702 /// ReturnType - The target type of return statements in this context, 703 /// or null if unknown. 704 QualType ReturnType; 705 706 void addCapture(ValueDecl *Var, bool isBlock, bool isByref, bool isNested, 707 SourceLocation Loc, SourceLocation EllipsisLoc, 708 QualType CaptureType, bool Invalid) { 709 Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc, 710 EllipsisLoc, CaptureType, Invalid)); 711 CaptureMap[Var] = Captures.size(); 712 } 713 714 void addVLATypeCapture(SourceLocation Loc, const VariableArrayType *VLAType, 715 QualType CaptureType) { 716 Captures.push_back(Capture(Capture::VLACapture, VLAType, 717 /*FIXME: IsNested*/ false, Loc, CaptureType)); 718 } 719 720 void addThisCapture(bool isNested, SourceLocation Loc, QualType CaptureType, 721 bool ByCopy); 722 723 /// Determine whether the C++ 'this' is captured. 724 bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; } 725 726 /// Retrieve the capture of C++ 'this', if it has been captured. 727 Capture &getCXXThisCapture() { 728 assert(isCXXThisCaptured() && "this has not been captured"); 729 return Captures[CXXThisCaptureIndex - 1]; 730 } 731 732 /// Determine whether the given variable has been captured. 733 bool isCaptured(ValueDecl *Var) const { return CaptureMap.count(Var); } 734 735 /// Determine whether the given variable-array type has been captured. 736 bool isVLATypeCaptured(const VariableArrayType *VAT) const; 737 738 /// Retrieve the capture of the given variable, if it has been 739 /// captured already. 740 Capture &getCapture(ValueDecl *Var) { 741 assert(isCaptured(Var) && "Variable has not been captured"); 742 return Captures[CaptureMap[Var] - 1]; 743 } 744 745 const Capture &getCapture(ValueDecl *Var) const { 746 llvm::DenseMap<ValueDecl *, unsigned>::const_iterator Known = 747 CaptureMap.find(Var); 748 assert(Known != CaptureMap.end() && "Variable has not been captured"); 749 return Captures[Known->second - 1]; 750 } 751 752 static bool classof(const FunctionScopeInfo *FSI) { 753 return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda 754 || FSI->Kind == SK_CapturedRegion; 755 } 756 }; 757 758 /// Retains information about a block that is currently being parsed. 759 class BlockScopeInfo final : public CapturingScopeInfo { 760 public: 761 BlockDecl *TheDecl; 762 763 /// TheScope - This is the scope for the block itself, which contains 764 /// arguments etc. 765 Scope *TheScope; 766 767 /// BlockType - The function type of the block, if one was given. 768 /// Its return type may be BuiltinType::Dependent. 769 QualType FunctionType; 770 771 BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block) 772 : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block), 773 TheScope(BlockScope) { 774 Kind = SK_Block; 775 } 776 777 ~BlockScopeInfo() override; 778 779 static bool classof(const FunctionScopeInfo *FSI) { 780 return FSI->Kind == SK_Block; 781 } 782 }; 783 784 /// Retains information about a captured region. 785 class CapturedRegionScopeInfo final : public CapturingScopeInfo { 786 public: 787 /// The CapturedDecl for this statement. 788 CapturedDecl *TheCapturedDecl; 789 790 /// The captured record type. 791 RecordDecl *TheRecordDecl; 792 793 /// This is the enclosing scope of the captured region. 794 Scope *TheScope; 795 796 /// The implicit parameter for the captured variables. 797 ImplicitParamDecl *ContextParam; 798 799 /// The kind of captured region. 800 unsigned short CapRegionKind; 801 802 unsigned short OpenMPLevel; 803 unsigned short OpenMPCaptureLevel; 804 805 CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD, 806 RecordDecl *RD, ImplicitParamDecl *Context, 807 CapturedRegionKind K, unsigned OpenMPLevel, 808 unsigned OpenMPCaptureLevel) 809 : CapturingScopeInfo(Diag, ImpCap_CapturedRegion), 810 TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S), 811 ContextParam(Context), CapRegionKind(K), OpenMPLevel(OpenMPLevel), 812 OpenMPCaptureLevel(OpenMPCaptureLevel) { 813 Kind = SK_CapturedRegion; 814 } 815 816 ~CapturedRegionScopeInfo() override; 817 818 /// A descriptive name for the kind of captured region this is. 819 StringRef getRegionName() const { 820 switch (CapRegionKind) { 821 case CR_Default: 822 return "default captured statement"; 823 case CR_ObjCAtFinally: 824 return "Objective-C @finally statement"; 825 case CR_OpenMP: 826 return "OpenMP region"; 827 } 828 llvm_unreachable("Invalid captured region kind!"); 829 } 830 831 static bool classof(const FunctionScopeInfo *FSI) { 832 return FSI->Kind == SK_CapturedRegion; 833 } 834 }; 835 836 class LambdaScopeInfo final : 837 public CapturingScopeInfo, public InventedTemplateParameterInfo { 838 public: 839 /// The class that describes the lambda. 840 CXXRecordDecl *Lambda = nullptr; 841 842 /// The lambda's compiler-generated \c operator(). 843 CXXMethodDecl *CallOperator = nullptr; 844 845 /// Indicate that we parsed the parameter list 846 /// at which point the mutability of the lambda 847 /// is known. 848 bool AfterParameterList = true; 849 850 /// Source range covering the lambda introducer [...]. 851 SourceRange IntroducerRange; 852 853 /// Source location of the '&' or '=' specifying the default capture 854 /// type, if any. 855 SourceLocation CaptureDefaultLoc; 856 857 /// The number of captures in the \c Captures list that are 858 /// explicit captures. 859 unsigned NumExplicitCaptures = 0; 860 861 /// Whether this is a mutable lambda. Until the mutable keyword is parsed, 862 /// we assume the lambda is mutable. 863 bool Mutable = true; 864 865 /// Whether the (empty) parameter list is explicit. 866 bool ExplicitParams = false; 867 868 /// Whether any of the capture expressions requires cleanups. 869 CleanupInfo Cleanup; 870 871 /// Whether the lambda contains an unexpanded parameter pack. 872 bool ContainsUnexpandedParameterPack = false; 873 874 /// Packs introduced by this lambda, if any. 875 SmallVector<NamedDecl*, 4> LocalPacks; 876 877 /// Source range covering the explicit template parameter list (if it exists). 878 SourceRange ExplicitTemplateParamsRange; 879 880 /// The requires-clause immediately following the explicit template parameter 881 /// list, if any. (Note that there may be another requires-clause included as 882 /// part of the lambda-declarator.) 883 ExprResult RequiresClause; 884 885 /// If this is a generic lambda, and the template parameter 886 /// list has been created (from the TemplateParams) then store 887 /// a reference to it (cache it to avoid reconstructing it). 888 TemplateParameterList *GLTemplateParameterList = nullptr; 889 890 /// Contains all variable-referring-expressions (i.e. DeclRefExprs 891 /// or MemberExprs) that refer to local variables in a generic lambda 892 /// or a lambda in a potentially-evaluated-if-used context. 893 /// 894 /// Potentially capturable variables of a nested lambda that might need 895 /// to be captured by the lambda are housed here. 896 /// This is specifically useful for generic lambdas or 897 /// lambdas within a potentially evaluated-if-used context. 898 /// If an enclosing variable is named in an expression of a lambda nested 899 /// within a generic lambda, we don't always know whether the variable 900 /// will truly be odr-used (i.e. need to be captured) by that nested lambda, 901 /// until its instantiation. But we still need to capture it in the 902 /// enclosing lambda if all intervening lambdas can capture the variable. 903 llvm::SmallVector<Expr*, 4> PotentiallyCapturingExprs; 904 905 /// Contains all variable-referring-expressions that refer 906 /// to local variables that are usable as constant expressions and 907 /// do not involve an odr-use (they may still need to be captured 908 /// if the enclosing full-expression is instantiation dependent). 909 llvm::SmallSet<Expr *, 8> NonODRUsedCapturingExprs; 910 911 /// A map of explicit capture indices to their introducer source ranges. 912 llvm::DenseMap<unsigned, SourceRange> ExplicitCaptureRanges; 913 914 /// Contains all of the variables defined in this lambda that shadow variables 915 /// that were defined in parent contexts. Used to avoid warnings when the 916 /// shadowed variables are uncaptured by this lambda. 917 struct ShadowedOuterDecl { 918 const VarDecl *VD; 919 const VarDecl *ShadowedDecl; 920 }; 921 llvm::SmallVector<ShadowedOuterDecl, 4> ShadowingDecls; 922 923 SourceLocation PotentialThisCaptureLocation; 924 925 LambdaScopeInfo(DiagnosticsEngine &Diag) 926 : CapturingScopeInfo(Diag, ImpCap_None) { 927 Kind = SK_Lambda; 928 } 929 930 /// Note when all explicit captures have been added. 931 void finishedExplicitCaptures() { 932 NumExplicitCaptures = Captures.size(); 933 } 934 935 static bool classof(const FunctionScopeInfo *FSI) { 936 return FSI->Kind == SK_Lambda; 937 } 938 939 /// Is this scope known to be for a generic lambda? (This will be false until 940 /// we parse a template parameter list or the first 'auto'-typed parameter). 941 bool isGenericLambda() const { 942 return !TemplateParams.empty() || GLTemplateParameterList; 943 } 944 945 /// Add a variable that might potentially be captured by the 946 /// lambda and therefore the enclosing lambdas. 947 /// 948 /// This is also used by enclosing lambda's to speculatively capture 949 /// variables that nested lambda's - depending on their enclosing 950 /// specialization - might need to capture. 951 /// Consider: 952 /// void f(int, int); <-- don't capture 953 /// void f(const int&, double); <-- capture 954 /// void foo() { 955 /// const int x = 10; 956 /// auto L = [=](auto a) { // capture 'x' 957 /// return [=](auto b) { 958 /// f(x, a); // we may or may not need to capture 'x' 959 /// }; 960 /// }; 961 /// } 962 void addPotentialCapture(Expr *VarExpr) { 963 assert(isa<DeclRefExpr>(VarExpr) || isa<MemberExpr>(VarExpr) || 964 isa<FunctionParmPackExpr>(VarExpr)); 965 PotentiallyCapturingExprs.push_back(VarExpr); 966 } 967 968 void addPotentialThisCapture(SourceLocation Loc) { 969 PotentialThisCaptureLocation = Loc; 970 } 971 972 bool hasPotentialThisCapture() const { 973 return PotentialThisCaptureLocation.isValid(); 974 } 975 976 /// Mark a variable's reference in a lambda as non-odr using. 977 /// 978 /// For generic lambdas, if a variable is named in a potentially evaluated 979 /// expression, where the enclosing full expression is dependent then we 980 /// must capture the variable (given a default capture). 981 /// This is accomplished by recording all references to variables 982 /// (DeclRefExprs or MemberExprs) within said nested lambda in its array of 983 /// PotentialCaptures. All such variables have to be captured by that lambda, 984 /// except for as described below. 985 /// If that variable is usable as a constant expression and is named in a 986 /// manner that does not involve its odr-use (e.g. undergoes 987 /// lvalue-to-rvalue conversion, or discarded) record that it is so. Upon the 988 /// act of analyzing the enclosing full expression (ActOnFinishFullExpr) 989 /// if we can determine that the full expression is not instantiation- 990 /// dependent, then we can entirely avoid its capture. 991 /// 992 /// const int n = 0; 993 /// [&] (auto x) { 994 /// (void)+n + x; 995 /// }; 996 /// Interestingly, this strategy would involve a capture of n, even though 997 /// it's obviously not odr-used here, because the full-expression is 998 /// instantiation-dependent. It could be useful to avoid capturing such 999 /// variables, even when they are referred to in an instantiation-dependent 1000 /// expression, if we can unambiguously determine that they shall never be 1001 /// odr-used. This would involve removal of the variable-referring-expression 1002 /// from the array of PotentialCaptures during the lvalue-to-rvalue 1003 /// conversions. But per the working draft N3797, (post-chicago 2013) we must 1004 /// capture such variables. 1005 /// Before anyone is tempted to implement a strategy for not-capturing 'n', 1006 /// consider the insightful warning in: 1007 /// /cfe-commits/Week-of-Mon-20131104/092596.html 1008 /// "The problem is that the set of captures for a lambda is part of the ABI 1009 /// (since lambda layout can be made visible through inline functions and the 1010 /// like), and there are no guarantees as to which cases we'll manage to build 1011 /// an lvalue-to-rvalue conversion in, when parsing a template -- some 1012 /// seemingly harmless change elsewhere in Sema could cause us to start or stop 1013 /// building such a node. So we need a rule that anyone can implement and get 1014 /// exactly the same result". 1015 void markVariableExprAsNonODRUsed(Expr *CapturingVarExpr) { 1016 assert(isa<DeclRefExpr>(CapturingVarExpr) || 1017 isa<MemberExpr>(CapturingVarExpr) || 1018 isa<FunctionParmPackExpr>(CapturingVarExpr)); 1019 NonODRUsedCapturingExprs.insert(CapturingVarExpr); 1020 } 1021 bool isVariableExprMarkedAsNonODRUsed(Expr *CapturingVarExpr) const { 1022 assert(isa<DeclRefExpr>(CapturingVarExpr) || 1023 isa<MemberExpr>(CapturingVarExpr) || 1024 isa<FunctionParmPackExpr>(CapturingVarExpr)); 1025 return NonODRUsedCapturingExprs.count(CapturingVarExpr); 1026 } 1027 void removePotentialCapture(Expr *E) { 1028 llvm::erase_value(PotentiallyCapturingExprs, E); 1029 } 1030 void clearPotentialCaptures() { 1031 PotentiallyCapturingExprs.clear(); 1032 PotentialThisCaptureLocation = SourceLocation(); 1033 } 1034 unsigned getNumPotentialVariableCaptures() const { 1035 return PotentiallyCapturingExprs.size(); 1036 } 1037 1038 bool hasPotentialCaptures() const { 1039 return getNumPotentialVariableCaptures() || 1040 PotentialThisCaptureLocation.isValid(); 1041 } 1042 1043 void visitPotentialCaptures( 1044 llvm::function_ref<void(ValueDecl *, Expr *)> Callback) const; 1045 }; 1046 1047 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy() 1048 : Base(nullptr, false) {} 1049 1050 FunctionScopeInfo::WeakObjectProfileTy 1051 FunctionScopeInfo::WeakObjectProfileTy::getSentinel() { 1052 FunctionScopeInfo::WeakObjectProfileTy Result; 1053 Result.Base.setInt(true); 1054 return Result; 1055 } 1056 1057 template <typename ExprT> 1058 void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) { 1059 assert(E); 1060 WeakUseVector &Uses = WeakObjectUses[WeakObjectProfileTy(E)]; 1061 Uses.push_back(WeakUseTy(E, IsRead)); 1062 } 1063 1064 inline void CapturingScopeInfo::addThisCapture(bool isNested, 1065 SourceLocation Loc, 1066 QualType CaptureType, 1067 bool ByCopy) { 1068 Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, CaptureType, 1069 ByCopy, /*Invalid*/ false)); 1070 CXXThisCaptureIndex = Captures.size(); 1071 } 1072 1073 } // namespace sema 1074 1075 } // namespace clang 1076 1077 #endif // LLVM_CLANG_SEMA_SCOPEINFO_H 1078