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