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