CFG.cpp revision 81bc7d07b701042371a5723b6f394cd2482ed7be
1//===--- CFG.cpp - Classes for representing and building CFGs----*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the CFG and CFGBuilder classes for representing and 11// building Control-Flow Graphs (CFGs) from ASTs. 12// 13//===----------------------------------------------------------------------===// 14 15#include "clang/Analysis/Support/SaveAndRestore.h" 16#include "clang/Analysis/CFG.h" 17#include "clang/AST/DeclCXX.h" 18#include "clang/AST/StmtVisitor.h" 19#include "clang/AST/PrettyPrinter.h" 20#include "llvm/Support/GraphWriter.h" 21#include "llvm/Support/Allocator.h" 22#include "llvm/Support/Format.h" 23#include "llvm/ADT/DenseMap.h" 24#include "llvm/ADT/SmallPtrSet.h" 25#include "llvm/ADT/OwningPtr.h" 26 27using namespace clang; 28 29namespace { 30 31static SourceLocation GetEndLoc(Decl* D) { 32 if (VarDecl* VD = dyn_cast<VarDecl>(D)) 33 if (Expr* Ex = VD->getInit()) 34 return Ex->getSourceRange().getEnd(); 35 36 return D->getLocation(); 37} 38 39class AddStmtChoice { 40public: 41 enum Kind { NotAlwaysAdd = 0, 42 AlwaysAdd = 1, 43 AsLValueNotAlwaysAdd = 2, 44 AlwaysAddAsLValue = 3 }; 45 46 AddStmtChoice(Kind kind) : k(kind) {} 47 48 bool alwaysAdd() const { return (unsigned)k & 0x1; } 49 bool asLValue() const { return k >= AsLValueNotAlwaysAdd; } 50 51private: 52 Kind k; 53}; 54 55/// LocalScope - Node in tree of local scopes created for C++ implicit 56/// destructor calls generation. It contains list of automatic variables 57/// declared in the scope and link to position in previous scope this scope 58/// began in. 59/// 60/// The process of creating local scopes is as follows: 61/// - Init CFGBuilder::ScopePos with invalid position (equivalent for null), 62/// - Before processing statements in scope (e.g. CompoundStmt) create 63/// LocalScope object using CFGBuilder::ScopePos as link to previous scope 64/// and set CFGBuilder::ScopePos to the end of new scope, 65/// - On every occurrence of VarDecl increase CFGBuilder::ScopePos if it points 66/// at this VarDecl, 67/// - For every normal (without jump) end of scope add to CFGBlock destructors 68/// for objects in the current scope, 69/// - For every jump add to CFGBlock destructors for objects 70/// between CFGBuilder::ScopePos and local scope position saved for jump 71/// target. Thanks to C++ restrictions on goto jumps we can be sure that 72/// jump target position will be on the path to root from CFGBuilder::ScopePos 73/// (adding any variable that doesn't need constructor to be called to 74/// LocalScope can break this assumption), 75/// 76class LocalScope { 77public: 78 typedef llvm::SmallVector<VarDecl*, 4> AutomaticVarsTy; 79 80 /// const_iterator - Iterates local scope backwards and jumps to previous 81 /// scope on reaching the beginning of currently iterated scope. 82 class const_iterator { 83 const LocalScope* Scope; 84 85 /// VarIter is guaranteed to be greater then 0 for every valid iterator. 86 /// Invalid iterator (with null Scope) has VarIter equal to 0. 87 unsigned VarIter; 88 89 public: 90 /// Create invalid iterator. Dereferencing invalid iterator is not allowed. 91 /// Incrementing invalid iterator is allowed and will result in invalid 92 /// iterator. 93 const_iterator() 94 : Scope(NULL), VarIter(0) {} 95 96 /// Create valid iterator. In case when S.Prev is an invalid iterator and 97 /// I is equal to 0, this will create invalid iterator. 98 const_iterator(const LocalScope& S, unsigned I) 99 : Scope(&S), VarIter(I) { 100 // Iterator to "end" of scope is not allowed. Handle it by going up 101 // in scopes tree possibly up to invalid iterator in the root. 102 if (VarIter == 0 && Scope) 103 *this = Scope->Prev; 104 } 105 106 VarDecl* const* operator->() const { 107 assert (Scope && "Dereferencing invalid iterator is not allowed"); 108 assert (VarIter != 0 && "Iterator has invalid value of VarIter member"); 109 return &Scope->Vars[VarIter - 1]; 110 } 111 VarDecl* operator*() const { 112 return *this->operator->(); 113 } 114 115 const_iterator& operator++() { 116 if (!Scope) 117 return *this; 118 119 assert (VarIter != 0 && "Iterator has invalid value of VarIter member"); 120 --VarIter; 121 if (VarIter == 0) 122 *this = Scope->Prev; 123 return *this; 124 } 125 const_iterator operator++(int) { 126 const_iterator P = *this; 127 ++*this; 128 return P; 129 } 130 131 bool operator==(const const_iterator& rhs) const { 132 return Scope == rhs.Scope && VarIter == rhs.VarIter; 133 } 134 bool operator!=(const const_iterator& rhs) const { 135 return !(*this == rhs); 136 } 137 138 operator bool() const { 139 return *this != const_iterator(); 140 } 141 142 int distance(const_iterator L); 143 }; 144 145 friend class const_iterator; 146 147private: 148 /// Automatic variables in order of declaration. 149 AutomaticVarsTy Vars; 150 /// Iterator to variable in previous scope that was declared just before 151 /// begin of this scope. 152 const_iterator Prev; 153 154public: 155 /// Constructs empty scope linked to previous scope in specified place. 156 LocalScope(const_iterator P) 157 : Vars() 158 , Prev(P) {} 159 160 /// Begin of scope in direction of CFG building (backwards). 161 const_iterator begin() const { return const_iterator(*this, Vars.size()); } 162 163 void addVar(VarDecl* VD) { 164 Vars.push_back(VD); 165 } 166}; 167 168/// distance - Calculates distance from this to L. L must be reachable from this 169/// (with use of ++ operator). Cost of calculating the distance is linear w.r.t. 170/// number of scopes between this and L. 171int LocalScope::const_iterator::distance(LocalScope::const_iterator L) { 172 int D = 0; 173 const_iterator F = *this; 174 while (F.Scope != L.Scope) { 175 assert (F != const_iterator() 176 && "L iterator is not reachable from F iterator."); 177 D += F.VarIter; 178 F = F.Scope->Prev; 179 } 180 D += F.VarIter - L.VarIter; 181 return D; 182} 183 184/// BlockScopePosPair - Structure for specifying position in CFG during its 185/// build process. It consists of CFGBlock that specifies position in CFG graph 186/// and LocalScope::const_iterator that specifies position in LocalScope graph. 187struct BlockScopePosPair { 188 BlockScopePosPair() {} 189 BlockScopePosPair(CFGBlock* B, LocalScope::const_iterator S) 190 : Block(B), ScopePos(S) {} 191 192 CFGBlock* Block; 193 LocalScope::const_iterator ScopePos; 194}; 195 196/// CFGBuilder - This class implements CFG construction from an AST. 197/// The builder is stateful: an instance of the builder should be used to only 198/// construct a single CFG. 199/// 200/// Example usage: 201/// 202/// CFGBuilder builder; 203/// CFG* cfg = builder.BuildAST(stmt1); 204/// 205/// CFG construction is done via a recursive walk of an AST. We actually parse 206/// the AST in reverse order so that the successor of a basic block is 207/// constructed prior to its predecessor. This allows us to nicely capture 208/// implicit fall-throughs without extra basic blocks. 209/// 210class CFGBuilder { 211 typedef BlockScopePosPair JumpTarget; 212 typedef BlockScopePosPair JumpSource; 213 214 ASTContext *Context; 215 llvm::OwningPtr<CFG> cfg; 216 217 CFGBlock* Block; 218 CFGBlock* Succ; 219 JumpTarget ContinueJumpTarget; 220 JumpTarget BreakJumpTarget; 221 CFGBlock* SwitchTerminatedBlock; 222 CFGBlock* DefaultCaseBlock; 223 CFGBlock* TryTerminatedBlock; 224 225 // Current position in local scope. 226 LocalScope::const_iterator ScopePos; 227 228 // LabelMap records the mapping from Label expressions to their jump targets. 229 typedef llvm::DenseMap<LabelStmt*, JumpTarget> LabelMapTy; 230 LabelMapTy LabelMap; 231 232 // A list of blocks that end with a "goto" that must be backpatched to their 233 // resolved targets upon completion of CFG construction. 234 typedef std::vector<JumpSource> BackpatchBlocksTy; 235 BackpatchBlocksTy BackpatchBlocks; 236 237 // A list of labels whose address has been taken (for indirect gotos). 238 typedef llvm::SmallPtrSet<LabelStmt*,5> LabelSetTy; 239 LabelSetTy AddressTakenLabels; 240 241 bool badCFG; 242 CFG::BuildOptions BuildOpts; 243 244public: 245 explicit CFGBuilder() : cfg(new CFG()), // crew a new CFG 246 Block(NULL), Succ(NULL), 247 SwitchTerminatedBlock(NULL), DefaultCaseBlock(NULL), 248 TryTerminatedBlock(NULL), badCFG(false) {} 249 250 // buildCFG - Used by external clients to construct the CFG. 251 CFG* buildCFG(const Decl *D, Stmt *Statement, ASTContext *C, 252 CFG::BuildOptions BO); 253 254private: 255 // Visitors to walk an AST and construct the CFG. 256 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc); 257 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc); 258 CFGBlock *VisitBlockExpr(BlockExpr* E, AddStmtChoice asc); 259 CFGBlock *VisitBreakStmt(BreakStmt *B); 260 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S); 261 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 262 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 263 CFGBlock *VisitCXXConstructExpr(CXXConstructExpr *C, AddStmtChoice asc); 264 CFGBlock *VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C, 265 AddStmtChoice asc); 266 CFGBlock *VisitCXXMemberCallExpr(CXXMemberCallExpr *C, AddStmtChoice asc); 267 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 268 CFGBlock *VisitCaseStmt(CaseStmt *C); 269 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 270 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 271 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, AddStmtChoice asc); 272 CFGBlock *VisitContinueStmt(ContinueStmt *C); 273 CFGBlock *VisitDeclStmt(DeclStmt *DS); 274 CFGBlock *VisitDeclSubExpr(Decl* D); 275 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 276 CFGBlock *VisitDoStmt(DoStmt *D); 277 CFGBlock *VisitForStmt(ForStmt *F); 278 CFGBlock *VisitGotoStmt(GotoStmt* G); 279 CFGBlock *VisitIfStmt(IfStmt *I); 280 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 281 CFGBlock *VisitLabelStmt(LabelStmt *L); 282 CFGBlock *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc); 283 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 284 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 285 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 286 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 287 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 288 CFGBlock *VisitReturnStmt(ReturnStmt* R); 289 CFGBlock *VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, AddStmtChoice asc); 290 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 291 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 292 CFGBlock *VisitWhileStmt(WhileStmt *W); 293 294 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 295 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 296 CFGBlock *VisitChildren(Stmt* S); 297 298 // NYS == Not Yet Supported 299 CFGBlock* NYS() { 300 badCFG = true; 301 return Block; 302 } 303 304 void autoCreateBlock() { if (!Block) Block = createBlock(); } 305 CFGBlock *createBlock(bool add_successor = true); 306 307 CFGBlock *addStmt(Stmt *S) { 308 return Visit(S, AddStmtChoice::AlwaysAdd); 309 } 310 CFGBlock *addInitializer(CXXBaseOrMemberInitializer *I); 311 void addAutomaticObjDtors(LocalScope::const_iterator B, 312 LocalScope::const_iterator E, Stmt* S); 313 void addImplicitDtorsForDestructor(const CXXDestructorDecl *DD); 314 315 // Local scopes creation. 316 LocalScope* createOrReuseLocalScope(LocalScope* Scope); 317 318 void addLocalScopeForStmt(Stmt* S); 319 LocalScope* addLocalScopeForDeclStmt(DeclStmt* DS, LocalScope* Scope = NULL); 320 LocalScope* addLocalScopeForVarDecl(VarDecl* VD, LocalScope* Scope = NULL); 321 322 void addLocalScopeAndDtors(Stmt* S); 323 324 // Interface to CFGBlock - adding CFGElements. 325 void AppendStmt(CFGBlock *B, Stmt *S, 326 AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 327 B->appendStmt(S, cfg->getBumpVectorContext(), asc.asLValue()); 328 } 329 void appendInitializer(CFGBlock *B, CXXBaseOrMemberInitializer *I) { 330 B->appendInitializer(I, cfg->getBumpVectorContext()); 331 } 332 void appendBaseDtor(CFGBlock *B, const CXXBaseSpecifier *BS) { 333 B->appendBaseDtor(BS, cfg->getBumpVectorContext()); 334 } 335 void appendMemberDtor(CFGBlock *B, FieldDecl *FD) { 336 B->appendMemberDtor(FD, cfg->getBumpVectorContext()); 337 } 338 339 void insertAutomaticObjDtors(CFGBlock* Blk, CFGBlock::iterator I, 340 LocalScope::const_iterator B, LocalScope::const_iterator E, Stmt* S); 341 void appendAutomaticObjDtors(CFGBlock* Blk, LocalScope::const_iterator B, 342 LocalScope::const_iterator E, Stmt* S); 343 void prependAutomaticObjDtorsWithTerminator(CFGBlock* Blk, 344 LocalScope::const_iterator B, LocalScope::const_iterator E); 345 346 void AddSuccessor(CFGBlock *B, CFGBlock *S) { 347 B->addSuccessor(S, cfg->getBumpVectorContext()); 348 } 349 350 /// TryResult - a class representing a variant over the values 351 /// 'true', 'false', or 'unknown'. This is returned by TryEvaluateBool, 352 /// and is used by the CFGBuilder to decide if a branch condition 353 /// can be decided up front during CFG construction. 354 class TryResult { 355 int X; 356 public: 357 TryResult(bool b) : X(b ? 1 : 0) {} 358 TryResult() : X(-1) {} 359 360 bool isTrue() const { return X == 1; } 361 bool isFalse() const { return X == 0; } 362 bool isKnown() const { return X >= 0; } 363 void negate() { 364 assert(isKnown()); 365 X ^= 0x1; 366 } 367 }; 368 369 /// TryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 370 /// if we can evaluate to a known value, otherwise return -1. 371 TryResult TryEvaluateBool(Expr *S) { 372 if (!BuildOpts.PruneTriviallyFalseEdges) 373 return TryResult(); 374 375 Expr::EvalResult Result; 376 if (!S->isTypeDependent() && !S->isValueDependent() && 377 S->Evaluate(Result, *Context) && Result.Val.isInt()) 378 return Result.Val.getInt().getBoolValue(); 379 380 return TryResult(); 381 } 382}; 383 384// FIXME: Add support for dependent-sized array types in C++? 385// Does it even make sense to build a CFG for an uninstantiated template? 386static VariableArrayType* FindVA(Type* t) { 387 while (ArrayType* vt = dyn_cast<ArrayType>(t)) { 388 if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt)) 389 if (vat->getSizeExpr()) 390 return vat; 391 392 t = vt->getElementType().getTypePtr(); 393 } 394 395 return 0; 396} 397 398/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 399/// arbitrary statement. Examples include a single expression or a function 400/// body (compound statement). The ownership of the returned CFG is 401/// transferred to the caller. If CFG construction fails, this method returns 402/// NULL. 403CFG* CFGBuilder::buildCFG(const Decl *D, Stmt* Statement, ASTContext* C, 404 CFG::BuildOptions BO) { 405 406 Context = C; 407 assert(cfg.get()); 408 if (!Statement) 409 return NULL; 410 411 BuildOpts = BO; 412 413 // Create an empty block that will serve as the exit block for the CFG. Since 414 // this is the first block added to the CFG, it will be implicitly registered 415 // as the exit block. 416 Succ = createBlock(); 417 assert(Succ == &cfg->getExit()); 418 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 419 420 if (BuildOpts.AddImplicitDtors) 421 if (const CXXDestructorDecl *DD = dyn_cast_or_null<CXXDestructorDecl>(D)) 422 addImplicitDtorsForDestructor(DD); 423 424 // Visit the statements and create the CFG. 425 CFGBlock *B = addStmt(Statement); 426 427 if (badCFG) 428 return NULL; 429 430 // For C++ constructor add initializers to CFG. 431 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 432 for (CXXConstructorDecl::init_const_reverse_iterator I = CD->init_rbegin(), 433 E = CD->init_rend(); I != E; ++I) { 434 B = addInitializer(*I); 435 if (badCFG) 436 return NULL; 437 } 438 } 439 440 if (B) 441 Succ = B; 442 443 // Backpatch the gotos whose label -> block mappings we didn't know when we 444 // encountered them. 445 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 446 E = BackpatchBlocks.end(); I != E; ++I ) { 447 448 CFGBlock* B = I->Block; 449 GotoStmt* G = cast<GotoStmt>(B->getTerminator()); 450 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 451 452 // If there is no target for the goto, then we are looking at an 453 // incomplete AST. Handle this by not registering a successor. 454 if (LI == LabelMap.end()) continue; 455 456 JumpTarget JT = LI->second; 457 prependAutomaticObjDtorsWithTerminator(B, I->ScopePos, JT.ScopePos); 458 AddSuccessor(B, JT.Block); 459 } 460 461 // Add successors to the Indirect Goto Dispatch block (if we have one). 462 if (CFGBlock* B = cfg->getIndirectGotoBlock()) 463 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 464 E = AddressTakenLabels.end(); I != E; ++I ) { 465 466 // Lookup the target block. 467 LabelMapTy::iterator LI = LabelMap.find(*I); 468 469 // If there is no target block that contains label, then we are looking 470 // at an incomplete AST. Handle this by not registering a successor. 471 if (LI == LabelMap.end()) continue; 472 473 AddSuccessor(B, LI->second.Block); 474 } 475 476 // Create an empty entry block that has no predecessors. 477 cfg->setEntry(createBlock()); 478 479 return cfg.take(); 480} 481 482/// createBlock - Used to lazily create blocks that are connected 483/// to the current (global) succcessor. 484CFGBlock* CFGBuilder::createBlock(bool add_successor) { 485 CFGBlock* B = cfg->createBlock(); 486 if (add_successor && Succ) 487 AddSuccessor(B, Succ); 488 return B; 489} 490 491/// addInitializer - Add C++ base or member initializer element to CFG. 492CFGBlock *CFGBuilder::addInitializer(CXXBaseOrMemberInitializer *I) { 493 if (!BuildOpts.AddInitializers) 494 return Block; 495 496 autoCreateBlock(); 497 appendInitializer(Block, I); 498 499 if (Expr *Init = I->getInit()) { 500 AddStmtChoice::Kind K = AddStmtChoice::NotAlwaysAdd; 501 if (FieldDecl *FD = I->getMember()) 502 if (FD->getType()->isReferenceType()) 503 K = AddStmtChoice::AsLValueNotAlwaysAdd; 504 505 return Visit(Init, AddStmtChoice(K)); 506 } 507 508 return Block; 509} 510 511/// addAutomaticObjDtors - Add to current block automatic objects destructors 512/// for objects in range of local scope positions. Use S as trigger statement 513/// for destructors. 514void CFGBuilder::addAutomaticObjDtors(LocalScope::const_iterator B, 515 LocalScope::const_iterator E, Stmt* S) { 516 if (!BuildOpts.AddImplicitDtors) 517 return; 518 519 if (B == E) 520 return; 521 522 autoCreateBlock(); 523 appendAutomaticObjDtors(Block, B, E, S); 524} 525 526/// addImplicitDtorsForDestructor - Add implicit destructors generated for 527/// base and member objects in destructor. 528void CFGBuilder::addImplicitDtorsForDestructor(const CXXDestructorDecl *DD) { 529 assert (BuildOpts.AddImplicitDtors 530 && "Can be called only when dtors should be added"); 531 const CXXRecordDecl *RD = DD->getParent(); 532 533 // At the end destroy virtual base objects. 534 for (CXXRecordDecl::base_class_const_iterator VI = RD->vbases_begin(), 535 VE = RD->vbases_end(); VI != VE; ++VI) { 536 const CXXRecordDecl *CD = VI->getType()->getAsCXXRecordDecl(); 537 if (!CD->hasTrivialDestructor()) { 538 autoCreateBlock(); 539 appendBaseDtor(Block, VI); 540 } 541 } 542 543 // Before virtual bases destroy direct base objects. 544 for (CXXRecordDecl::base_class_const_iterator BI = RD->bases_begin(), 545 BE = RD->bases_end(); BI != BE; ++BI) { 546 if (!BI->isVirtual()) { 547 const CXXRecordDecl *CD = BI->getType()->getAsCXXRecordDecl(); 548 if (!CD->hasTrivialDestructor()) { 549 autoCreateBlock(); 550 appendBaseDtor(Block, BI); 551 } 552 } 553 } 554 555 // First destroy member objects. 556 for (CXXRecordDecl::field_iterator FI = RD->field_begin(), 557 FE = RD->field_end(); FI != FE; ++FI) { 558 // Check for constant size array. Set type to array element type. 559 QualType QT = FI->getType(); 560 if (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) { 561 if (AT->getSize() == 0) 562 continue; 563 QT = AT->getElementType(); 564 } 565 566 if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl()) 567 if (!CD->hasTrivialDestructor()) { 568 autoCreateBlock(); 569 appendMemberDtor(Block, *FI); 570 } 571 } 572} 573 574/// createOrReuseLocalScope - If Scope is NULL create new LocalScope. Either 575/// way return valid LocalScope object. 576LocalScope* CFGBuilder::createOrReuseLocalScope(LocalScope* Scope) { 577 if (!Scope) { 578 Scope = cfg->getAllocator().Allocate<LocalScope>(); 579 new (Scope) LocalScope(ScopePos); 580 } 581 return Scope; 582} 583 584/// addLocalScopeForStmt - Add LocalScope to local scopes tree for statement 585/// that should create implicit scope (e.g. if/else substatements). 586void CFGBuilder::addLocalScopeForStmt(Stmt* S) { 587 if (!BuildOpts.AddImplicitDtors) 588 return; 589 590 LocalScope *Scope = 0; 591 592 // For compound statement we will be creating explicit scope. 593 if (CompoundStmt* CS = dyn_cast<CompoundStmt>(S)) { 594 for (CompoundStmt::body_iterator BI = CS->body_begin(), BE = CS->body_end() 595 ; BI != BE; ++BI) { 596 Stmt* SI = *BI; 597 if (LabelStmt* LS = dyn_cast<LabelStmt>(SI)) 598 SI = LS->getSubStmt(); 599 if (DeclStmt* DS = dyn_cast<DeclStmt>(SI)) 600 Scope = addLocalScopeForDeclStmt(DS, Scope); 601 } 602 return; 603 } 604 605 // For any other statement scope will be implicit and as such will be 606 // interesting only for DeclStmt. 607 if (LabelStmt* LS = dyn_cast<LabelStmt>(S)) 608 S = LS->getSubStmt(); 609 if (DeclStmt* DS = dyn_cast<DeclStmt>(S)) 610 addLocalScopeForDeclStmt(DS); 611} 612 613/// addLocalScopeForDeclStmt - Add LocalScope for declaration statement. Will 614/// reuse Scope if not NULL. 615LocalScope* CFGBuilder::addLocalScopeForDeclStmt(DeclStmt* DS, 616 LocalScope* Scope) { 617 if (!BuildOpts.AddImplicitDtors) 618 return Scope; 619 620 for (DeclStmt::decl_iterator DI = DS->decl_begin(), DE = DS->decl_end() 621 ; DI != DE; ++DI) { 622 if (VarDecl* VD = dyn_cast<VarDecl>(*DI)) 623 Scope = addLocalScopeForVarDecl(VD, Scope); 624 } 625 return Scope; 626} 627 628/// addLocalScopeForVarDecl - Add LocalScope for variable declaration. It will 629/// create add scope for automatic objects and temporary objects bound to 630/// const reference. Will reuse Scope if not NULL. 631LocalScope* CFGBuilder::addLocalScopeForVarDecl(VarDecl* VD, 632 LocalScope* Scope) { 633 if (!BuildOpts.AddImplicitDtors) 634 return Scope; 635 636 // Check if variable is local. 637 switch (VD->getStorageClass()) { 638 case SC_None: 639 case SC_Auto: 640 case SC_Register: 641 break; 642 default: return Scope; 643 } 644 645 // Check for const references bound to temporary. Set type to pointee. 646 QualType QT = VD->getType(); 647 if (const ReferenceType* RT = QT.getTypePtr()->getAs<ReferenceType>()) { 648 QT = RT->getPointeeType(); 649 if (!QT.isConstQualified()) 650 return Scope; 651 if (!VD->getInit() || !VD->getInit()->Classify(*Context).isRValue()) 652 return Scope; 653 } 654 655 // Check for constant size array. Set type to array element type. 656 if (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) { 657 if (AT->getSize() == 0) 658 return Scope; 659 QT = AT->getElementType(); 660 } 661 662 // Check if type is a C++ class with non-trivial destructor. 663 if (const CXXRecordDecl* CD = QT->getAsCXXRecordDecl()) 664 if (!CD->hasTrivialDestructor()) { 665 // Add the variable to scope 666 Scope = createOrReuseLocalScope(Scope); 667 Scope->addVar(VD); 668 ScopePos = Scope->begin(); 669 } 670 return Scope; 671} 672 673/// addLocalScopeAndDtors - For given statement add local scope for it and 674/// add destructors that will cleanup the scope. Will reuse Scope if not NULL. 675void CFGBuilder::addLocalScopeAndDtors(Stmt* S) { 676 if (!BuildOpts.AddImplicitDtors) 677 return; 678 679 LocalScope::const_iterator scopeBeginPos = ScopePos; 680 addLocalScopeForStmt(S); 681 addAutomaticObjDtors(ScopePos, scopeBeginPos, S); 682} 683 684/// insertAutomaticObjDtors - Insert destructor CFGElements for variables with 685/// automatic storage duration to CFGBlock's elements vector. Insertion will be 686/// performed in place specified with iterator. 687void CFGBuilder::insertAutomaticObjDtors(CFGBlock* Blk, CFGBlock::iterator I, 688 LocalScope::const_iterator B, LocalScope::const_iterator E, Stmt* S) { 689 BumpVectorContext& C = cfg->getBumpVectorContext(); 690 I = Blk->beginAutomaticObjDtorsInsert(I, B.distance(E), C); 691 while (B != E) 692 I = Blk->insertAutomaticObjDtor(I, *B++, S); 693} 694 695/// appendAutomaticObjDtors - Append destructor CFGElements for variables with 696/// automatic storage duration to CFGBlock's elements vector. Elements will be 697/// appended to physical end of the vector which happens to be logical 698/// beginning. 699void CFGBuilder::appendAutomaticObjDtors(CFGBlock* Blk, 700 LocalScope::const_iterator B, LocalScope::const_iterator E, Stmt* S) { 701 insertAutomaticObjDtors(Blk, Blk->begin(), B, E, S); 702} 703 704/// prependAutomaticObjDtorsWithTerminator - Prepend destructor CFGElements for 705/// variables with automatic storage duration to CFGBlock's elements vector. 706/// Elements will be prepended to physical beginning of the vector which 707/// happens to be logical end. Use blocks terminator as statement that specifies 708/// destructors call site. 709void CFGBuilder::prependAutomaticObjDtorsWithTerminator(CFGBlock* Blk, 710 LocalScope::const_iterator B, LocalScope::const_iterator E) { 711 insertAutomaticObjDtors(Blk, Blk->end(), B, E, Blk->getTerminator()); 712} 713 714/// Visit - Walk the subtree of a statement and add extra 715/// blocks for ternary operators, &&, and ||. We also process "," and 716/// DeclStmts (which may contain nested control-flow). 717CFGBlock* CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 718tryAgain: 719 if (!S) { 720 badCFG = true; 721 return 0; 722 } 723 switch (S->getStmtClass()) { 724 default: 725 return VisitStmt(S, asc); 726 727 case Stmt::AddrLabelExprClass: 728 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 729 730 case Stmt::BinaryOperatorClass: 731 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 732 733 case Stmt::BlockExprClass: 734 return VisitBlockExpr(cast<BlockExpr>(S), asc); 735 736 case Stmt::BreakStmtClass: 737 return VisitBreakStmt(cast<BreakStmt>(S)); 738 739 case Stmt::CallExprClass: 740 case Stmt::CXXOperatorCallExprClass: 741 return VisitCallExpr(cast<CallExpr>(S), asc); 742 743 case Stmt::CaseStmtClass: 744 return VisitCaseStmt(cast<CaseStmt>(S)); 745 746 case Stmt::ChooseExprClass: 747 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 748 749 case Stmt::CompoundStmtClass: 750 return VisitCompoundStmt(cast<CompoundStmt>(S)); 751 752 case Stmt::ConditionalOperatorClass: 753 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 754 755 case Stmt::ContinueStmtClass: 756 return VisitContinueStmt(cast<ContinueStmt>(S)); 757 758 case Stmt::CXXCatchStmtClass: 759 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 760 761 case Stmt::CXXExprWithTemporariesClass: { 762 // FIXME: Handle temporaries. For now, just visit the subexpression 763 // so we don't artificially create extra blocks. 764 return Visit(cast<CXXExprWithTemporaries>(S)->getSubExpr(), asc); 765 } 766 767 case Stmt::CXXConstructExprClass: 768 return VisitCXXConstructExpr(cast<CXXConstructExpr>(S), asc); 769 770 case Stmt::CXXTemporaryObjectExprClass: 771 return VisitCXXTemporaryObjectExpr(cast<CXXTemporaryObjectExpr>(S), asc); 772 773 case Stmt::CXXMemberCallExprClass: 774 return VisitCXXMemberCallExpr(cast<CXXMemberCallExpr>(S), asc); 775 776 case Stmt::CXXThrowExprClass: 777 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 778 779 case Stmt::CXXTryStmtClass: 780 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 781 782 case Stmt::DeclStmtClass: 783 return VisitDeclStmt(cast<DeclStmt>(S)); 784 785 case Stmt::DefaultStmtClass: 786 return VisitDefaultStmt(cast<DefaultStmt>(S)); 787 788 case Stmt::DoStmtClass: 789 return VisitDoStmt(cast<DoStmt>(S)); 790 791 case Stmt::ForStmtClass: 792 return VisitForStmt(cast<ForStmt>(S)); 793 794 case Stmt::GotoStmtClass: 795 return VisitGotoStmt(cast<GotoStmt>(S)); 796 797 case Stmt::IfStmtClass: 798 return VisitIfStmt(cast<IfStmt>(S)); 799 800 case Stmt::IndirectGotoStmtClass: 801 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 802 803 case Stmt::LabelStmtClass: 804 return VisitLabelStmt(cast<LabelStmt>(S)); 805 806 case Stmt::MemberExprClass: 807 return VisitMemberExpr(cast<MemberExpr>(S), asc); 808 809 case Stmt::ObjCAtCatchStmtClass: 810 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 811 812 case Stmt::ObjCAtSynchronizedStmtClass: 813 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 814 815 case Stmt::ObjCAtThrowStmtClass: 816 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 817 818 case Stmt::ObjCAtTryStmtClass: 819 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 820 821 case Stmt::ObjCForCollectionStmtClass: 822 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 823 824 case Stmt::ParenExprClass: 825 S = cast<ParenExpr>(S)->getSubExpr(); 826 goto tryAgain; 827 828 case Stmt::NullStmtClass: 829 return Block; 830 831 case Stmt::ReturnStmtClass: 832 return VisitReturnStmt(cast<ReturnStmt>(S)); 833 834 case Stmt::SizeOfAlignOfExprClass: 835 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 836 837 case Stmt::StmtExprClass: 838 return VisitStmtExpr(cast<StmtExpr>(S), asc); 839 840 case Stmt::SwitchStmtClass: 841 return VisitSwitchStmt(cast<SwitchStmt>(S)); 842 843 case Stmt::WhileStmtClass: 844 return VisitWhileStmt(cast<WhileStmt>(S)); 845 } 846} 847 848CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 849 if (asc.alwaysAdd()) { 850 autoCreateBlock(); 851 AppendStmt(Block, S, asc); 852 } 853 854 return VisitChildren(S); 855} 856 857/// VisitChildren - Visit the children of a Stmt. 858CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 859 CFGBlock *B = Block; 860 for (Stmt::child_iterator I = Terminator->child_begin(), 861 E = Terminator->child_end(); I != E; ++I) { 862 if (*I) B = Visit(*I); 863 } 864 return B; 865} 866 867CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 868 AddStmtChoice asc) { 869 AddressTakenLabels.insert(A->getLabel()); 870 871 if (asc.alwaysAdd()) { 872 autoCreateBlock(); 873 AppendStmt(Block, A, asc); 874 } 875 876 return Block; 877} 878 879CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 880 AddStmtChoice asc) { 881 if (B->isLogicalOp()) { // && or || 882 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 883 AppendStmt(ConfluenceBlock, B, asc); 884 885 if (badCFG) 886 return 0; 887 888 // create the block evaluating the LHS 889 CFGBlock* LHSBlock = createBlock(false); 890 LHSBlock->setTerminator(B); 891 892 // create the block evaluating the RHS 893 Succ = ConfluenceBlock; 894 Block = NULL; 895 CFGBlock* RHSBlock = addStmt(B->getRHS()); 896 897 if (RHSBlock) { 898 if (badCFG) 899 return 0; 900 } 901 else { 902 // Create an empty block for cases where the RHS doesn't require 903 // any explicit statements in the CFG. 904 RHSBlock = createBlock(); 905 } 906 907 // See if this is a known constant. 908 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 909 if (KnownVal.isKnown() && (B->getOpcode() == BO_LOr)) 910 KnownVal.negate(); 911 912 // Now link the LHSBlock with RHSBlock. 913 if (B->getOpcode() == BO_LOr) { 914 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 915 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 916 } else { 917 assert(B->getOpcode() == BO_LAnd); 918 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 919 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 920 } 921 922 // Generate the blocks for evaluating the LHS. 923 Block = LHSBlock; 924 return addStmt(B->getLHS()); 925 } 926 else if (B->getOpcode() == BO_Comma) { // , 927 autoCreateBlock(); 928 AppendStmt(Block, B, asc); 929 addStmt(B->getRHS()); 930 return addStmt(B->getLHS()); 931 } 932 else if (B->isAssignmentOp()) { 933 if (asc.alwaysAdd()) { 934 autoCreateBlock(); 935 AppendStmt(Block, B, asc); 936 } 937 938 Visit(B->getLHS(), AddStmtChoice::AsLValueNotAlwaysAdd); 939 return Visit(B->getRHS()); 940 } 941 942 if (asc.alwaysAdd()) { 943 autoCreateBlock(); 944 AppendStmt(Block, B, asc); 945 } 946 947 CFGBlock *RBlock = Visit(B->getRHS()); 948 CFGBlock *LBlock = Visit(B->getLHS()); 949 // If visiting RHS causes us to finish 'Block', e.g. the RHS is a StmtExpr 950 // containing a DoStmt, and the LHS doesn't create a new block, then we should 951 // return RBlock. Otherwise we'll incorrectly return NULL. 952 return (LBlock ? LBlock : RBlock); 953} 954 955CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 956 if (asc.alwaysAdd()) { 957 autoCreateBlock(); 958 AppendStmt(Block, E, asc); 959 } 960 return Block; 961} 962 963CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 964 // "break" is a control-flow statement. Thus we stop processing the current 965 // block. 966 if (badCFG) 967 return 0; 968 969 // Now create a new block that ends with the break statement. 970 Block = createBlock(false); 971 Block->setTerminator(B); 972 973 // If there is no target for the break, then we are looking at an incomplete 974 // AST. This means that the CFG cannot be constructed. 975 if (BreakJumpTarget.Block) { 976 addAutomaticObjDtors(ScopePos, BreakJumpTarget.ScopePos, B); 977 AddSuccessor(Block, BreakJumpTarget.Block); 978 } else 979 badCFG = true; 980 981 982 return Block; 983} 984 985static bool CanThrow(Expr *E) { 986 QualType Ty = E->getType(); 987 if (Ty->isFunctionPointerType()) 988 Ty = Ty->getAs<PointerType>()->getPointeeType(); 989 else if (Ty->isBlockPointerType()) 990 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 991 992 const FunctionType *FT = Ty->getAs<FunctionType>(); 993 if (FT) { 994 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 995 if (Proto->hasEmptyExceptionSpec()) 996 return false; 997 } 998 return true; 999} 1000 1001CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 1002 // If this is a call to a no-return function, this stops the block here. 1003 bool NoReturn = false; 1004 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 1005 NoReturn = true; 1006 } 1007 1008 bool AddEHEdge = false; 1009 1010 // Languages without exceptions are assumed to not throw. 1011 if (Context->getLangOptions().Exceptions) { 1012 if (BuildOpts.AddEHEdges) 1013 AddEHEdge = true; 1014 } 1015 1016 if (FunctionDecl *FD = C->getDirectCallee()) { 1017 if (FD->hasAttr<NoReturnAttr>()) 1018 NoReturn = true; 1019 if (FD->hasAttr<NoThrowAttr>()) 1020 AddEHEdge = false; 1021 } 1022 1023 if (!CanThrow(C->getCallee())) 1024 AddEHEdge = false; 1025 1026 if (!NoReturn && !AddEHEdge) { 1027 if (asc.asLValue()) 1028 return VisitStmt(C, AddStmtChoice::AlwaysAddAsLValue); 1029 else 1030 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 1031 } 1032 1033 if (Block) { 1034 Succ = Block; 1035 if (badCFG) 1036 return 0; 1037 } 1038 1039 Block = createBlock(!NoReturn); 1040 AppendStmt(Block, C, asc); 1041 1042 if (NoReturn) { 1043 // Wire this to the exit block directly. 1044 AddSuccessor(Block, &cfg->getExit()); 1045 } 1046 if (AddEHEdge) { 1047 // Add exceptional edges. 1048 if (TryTerminatedBlock) 1049 AddSuccessor(Block, TryTerminatedBlock); 1050 else 1051 AddSuccessor(Block, &cfg->getExit()); 1052 } 1053 1054 return VisitChildren(C); 1055} 1056 1057CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 1058 AddStmtChoice asc) { 1059 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 1060 AppendStmt(ConfluenceBlock, C, asc); 1061 if (badCFG) 1062 return 0; 1063 1064 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 1065 : AddStmtChoice::AlwaysAdd; 1066 1067 Succ = ConfluenceBlock; 1068 Block = NULL; 1069 CFGBlock* LHSBlock = Visit(C->getLHS(), asc); 1070 if (badCFG) 1071 return 0; 1072 1073 Succ = ConfluenceBlock; 1074 Block = NULL; 1075 CFGBlock* RHSBlock = Visit(C->getRHS(), asc); 1076 if (badCFG) 1077 return 0; 1078 1079 Block = createBlock(false); 1080 // See if this is a known constant. 1081 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 1082 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 1083 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 1084 Block->setTerminator(C); 1085 return addStmt(C->getCond()); 1086} 1087 1088 1089CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 1090 addLocalScopeAndDtors(C); 1091 CFGBlock* LastBlock = Block; 1092 1093 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 1094 I != E; ++I ) { 1095 // If we hit a segment of code just containing ';' (NullStmts), we can 1096 // get a null block back. In such cases, just use the LastBlock 1097 if (CFGBlock *newBlock = addStmt(*I)) 1098 LastBlock = newBlock; 1099 1100 if (badCFG) 1101 return NULL; 1102 } 1103 1104 return LastBlock; 1105} 1106 1107CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 1108 AddStmtChoice asc) { 1109 // Create the confluence block that will "merge" the results of the ternary 1110 // expression. 1111 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 1112 AppendStmt(ConfluenceBlock, C, asc); 1113 if (badCFG) 1114 return 0; 1115 1116 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 1117 : AddStmtChoice::AlwaysAdd; 1118 1119 // Create a block for the LHS expression if there is an LHS expression. A 1120 // GCC extension allows LHS to be NULL, causing the condition to be the 1121 // value that is returned instead. 1122 // e.g: x ?: y is shorthand for: x ? x : y; 1123 Succ = ConfluenceBlock; 1124 Block = NULL; 1125 CFGBlock* LHSBlock = NULL; 1126 if (C->getLHS()) { 1127 LHSBlock = Visit(C->getLHS(), asc); 1128 if (badCFG) 1129 return 0; 1130 Block = NULL; 1131 } 1132 1133 // Create the block for the RHS expression. 1134 Succ = ConfluenceBlock; 1135 CFGBlock* RHSBlock = Visit(C->getRHS(), asc); 1136 if (badCFG) 1137 return 0; 1138 1139 // Create the block that will contain the condition. 1140 Block = createBlock(false); 1141 1142 // See if this is a known constant. 1143 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 1144 if (LHSBlock) { 1145 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 1146 } else { 1147 if (KnownVal.isFalse()) { 1148 // If we know the condition is false, add NULL as the successor for 1149 // the block containing the condition. In this case, the confluence 1150 // block will have just one predecessor. 1151 AddSuccessor(Block, 0); 1152 assert(ConfluenceBlock->pred_size() == 1); 1153 } else { 1154 // If we have no LHS expression, add the ConfluenceBlock as a direct 1155 // successor for the block containing the condition. Moreover, we need to 1156 // reverse the order of the predecessors in the ConfluenceBlock because 1157 // the RHSBlock will have been added to the succcessors already, and we 1158 // want the first predecessor to the the block containing the expression 1159 // for the case when the ternary expression evaluates to true. 1160 AddSuccessor(Block, ConfluenceBlock); 1161 assert(ConfluenceBlock->pred_size() == 2); 1162 std::reverse(ConfluenceBlock->pred_begin(), 1163 ConfluenceBlock->pred_end()); 1164 } 1165 } 1166 1167 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 1168 Block->setTerminator(C); 1169 return addStmt(C->getCond()); 1170} 1171 1172CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 1173 autoCreateBlock(); 1174 1175 if (DS->isSingleDecl()) { 1176 AppendStmt(Block, DS); 1177 return VisitDeclSubExpr(DS->getSingleDecl()); 1178 } 1179 1180 CFGBlock *B = 0; 1181 1182 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 1183 typedef llvm::SmallVector<Decl*,10> BufTy; 1184 BufTy Buf(DS->decl_begin(), DS->decl_end()); 1185 1186 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 1187 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 1188 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 1189 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 1190 1191 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 1192 // automatically freed with the CFG. 1193 DeclGroupRef DG(*I); 1194 Decl *D = *I; 1195 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 1196 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 1197 1198 // Append the fake DeclStmt to block. 1199 AppendStmt(Block, DSNew); 1200 B = VisitDeclSubExpr(D); 1201 } 1202 1203 return B; 1204} 1205 1206/// VisitDeclSubExpr - Utility method to add block-level expressions for 1207/// initializers in Decls. 1208CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 1209 assert(Block); 1210 1211 VarDecl *VD = dyn_cast<VarDecl>(D); 1212 1213 if (!VD) 1214 return Block; 1215 1216 Expr *Init = VD->getInit(); 1217 1218 if (Init) { 1219 AddStmtChoice::Kind k = 1220 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 1221 : AddStmtChoice::NotAlwaysAdd; 1222 Visit(Init, AddStmtChoice(k)); 1223 } 1224 1225 // If the type of VD is a VLA, then we must process its size expressions. 1226 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 1227 VA = FindVA(VA->getElementType().getTypePtr())) 1228 Block = addStmt(VA->getSizeExpr()); 1229 1230 // Remove variable from local scope. 1231 if (ScopePos && VD == *ScopePos) 1232 ++ScopePos; 1233 1234 return Block; 1235} 1236 1237CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 1238 // We may see an if statement in the middle of a basic block, or it may be the 1239 // first statement we are processing. In either case, we create a new basic 1240 // block. First, we create the blocks for the then...else statements, and 1241 // then we create the block containing the if statement. If we were in the 1242 // middle of a block, we stop processing that block. That block is then the 1243 // implicit successor for the "then" and "else" clauses. 1244 1245 // Save local scope position because in case of condition variable ScopePos 1246 // won't be restored when traversing AST. 1247 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 1248 1249 // Create local scope for possible condition variable. 1250 // Store scope position. Add implicit destructor. 1251 if (VarDecl* VD = I->getConditionVariable()) { 1252 LocalScope::const_iterator BeginScopePos = ScopePos; 1253 addLocalScopeForVarDecl(VD); 1254 addAutomaticObjDtors(ScopePos, BeginScopePos, I); 1255 } 1256 1257 // The block we were proccessing is now finished. Make it the successor 1258 // block. 1259 if (Block) { 1260 Succ = Block; 1261 if (badCFG) 1262 return 0; 1263 } 1264 1265 // Process the false branch. 1266 CFGBlock* ElseBlock = Succ; 1267 1268 if (Stmt* Else = I->getElse()) { 1269 SaveAndRestore<CFGBlock*> sv(Succ); 1270 1271 // NULL out Block so that the recursive call to Visit will 1272 // create a new basic block. 1273 Block = NULL; 1274 1275 // If branch is not a compound statement create implicit scope 1276 // and add destructors. 1277 if (!isa<CompoundStmt>(Else)) 1278 addLocalScopeAndDtors(Else); 1279 1280 ElseBlock = addStmt(Else); 1281 1282 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 1283 ElseBlock = sv.get(); 1284 else if (Block) { 1285 if (badCFG) 1286 return 0; 1287 } 1288 } 1289 1290 // Process the true branch. 1291 CFGBlock* ThenBlock; 1292 { 1293 Stmt* Then = I->getThen(); 1294 assert(Then); 1295 SaveAndRestore<CFGBlock*> sv(Succ); 1296 Block = NULL; 1297 1298 // If branch is not a compound statement create implicit scope 1299 // and add destructors. 1300 if (!isa<CompoundStmt>(Then)) 1301 addLocalScopeAndDtors(Then); 1302 1303 ThenBlock = addStmt(Then); 1304 1305 if (!ThenBlock) { 1306 // We can reach here if the "then" body has all NullStmts. 1307 // Create an empty block so we can distinguish between true and false 1308 // branches in path-sensitive analyses. 1309 ThenBlock = createBlock(false); 1310 AddSuccessor(ThenBlock, sv.get()); 1311 } else if (Block) { 1312 if (badCFG) 1313 return 0; 1314 } 1315 } 1316 1317 // Now create a new block containing the if statement. 1318 Block = createBlock(false); 1319 1320 // Set the terminator of the new block to the If statement. 1321 Block->setTerminator(I); 1322 1323 // See if this is a known constant. 1324 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 1325 1326 // Now add the successors. 1327 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 1328 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 1329 1330 // Add the condition as the last statement in the new block. This may create 1331 // new blocks as the condition may contain control-flow. Any newly created 1332 // blocks will be pointed to be "Block". 1333 Block = addStmt(I->getCond()); 1334 1335 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 1336 // and the condition variable initialization to the CFG. 1337 if (VarDecl *VD = I->getConditionVariable()) { 1338 if (Expr *Init = VD->getInit()) { 1339 autoCreateBlock(); 1340 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 1341 addStmt(Init); 1342 } 1343 } 1344 1345 return Block; 1346} 1347 1348 1349CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 1350 // If we were in the middle of a block we stop processing that block. 1351 // 1352 // NOTE: If a "return" appears in the middle of a block, this means that the 1353 // code afterwards is DEAD (unreachable). We still keep a basic block 1354 // for that code; a simple "mark-and-sweep" from the entry block will be 1355 // able to report such dead blocks. 1356 1357 // Create the new block. 1358 Block = createBlock(false); 1359 1360 // The Exit block is the only successor. 1361 addAutomaticObjDtors(ScopePos, LocalScope::const_iterator(), R); 1362 AddSuccessor(Block, &cfg->getExit()); 1363 1364 // Add the return statement to the block. This may create new blocks if R 1365 // contains control-flow (short-circuit operations). 1366 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 1367} 1368 1369CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 1370 // Get the block of the labeled statement. Add it to our map. 1371 addStmt(L->getSubStmt()); 1372 CFGBlock* LabelBlock = Block; 1373 1374 if (!LabelBlock) // This can happen when the body is empty, i.e. 1375 LabelBlock = createBlock(); // scopes that only contains NullStmts. 1376 1377 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 1378 LabelMap[ L ] = JumpTarget(LabelBlock, ScopePos); 1379 1380 // Labels partition blocks, so this is the end of the basic block we were 1381 // processing (L is the block's label). Because this is label (and we have 1382 // already processed the substatement) there is no extra control-flow to worry 1383 // about. 1384 LabelBlock->setLabel(L); 1385 if (badCFG) 1386 return 0; 1387 1388 // We set Block to NULL to allow lazy creation of a new block (if necessary); 1389 Block = NULL; 1390 1391 // This block is now the implicit successor of other blocks. 1392 Succ = LabelBlock; 1393 1394 return LabelBlock; 1395} 1396 1397CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 1398 // Goto is a control-flow statement. Thus we stop processing the current 1399 // block and create a new one. 1400 1401 Block = createBlock(false); 1402 Block->setTerminator(G); 1403 1404 // If we already know the mapping to the label block add the successor now. 1405 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 1406 1407 if (I == LabelMap.end()) 1408 // We will need to backpatch this block later. 1409 BackpatchBlocks.push_back(JumpSource(Block, ScopePos)); 1410 else { 1411 JumpTarget JT = I->second; 1412 addAutomaticObjDtors(ScopePos, JT.ScopePos, G); 1413 AddSuccessor(Block, JT.Block); 1414 } 1415 1416 return Block; 1417} 1418 1419CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 1420 CFGBlock* LoopSuccessor = NULL; 1421 1422 // Save local scope position because in case of condition variable ScopePos 1423 // won't be restored when traversing AST. 1424 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 1425 1426 // Create local scope for init statement and possible condition variable. 1427 // Add destructor for init statement and condition variable. 1428 // Store scope position for continue statement. 1429 if (Stmt* Init = F->getInit()) 1430 addLocalScopeForStmt(Init); 1431 LocalScope::const_iterator LoopBeginScopePos = ScopePos; 1432 1433 if (VarDecl* VD = F->getConditionVariable()) 1434 addLocalScopeForVarDecl(VD); 1435 LocalScope::const_iterator ContinueScopePos = ScopePos; 1436 1437 addAutomaticObjDtors(ScopePos, save_scope_pos.get(), F); 1438 1439 // "for" is a control-flow statement. Thus we stop processing the current 1440 // block. 1441 if (Block) { 1442 if (badCFG) 1443 return 0; 1444 LoopSuccessor = Block; 1445 } else 1446 LoopSuccessor = Succ; 1447 1448 // Save the current value for the break targets. 1449 // All breaks should go to the code following the loop. 1450 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget); 1451 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 1452 1453 // Because of short-circuit evaluation, the condition of the loop can span 1454 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1455 // evaluate the condition. 1456 CFGBlock* ExitConditionBlock = createBlock(false); 1457 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1458 1459 // Set the terminator for the "exit" condition block. 1460 ExitConditionBlock->setTerminator(F); 1461 1462 // Now add the actual condition to the condition block. Because the condition 1463 // itself may contain control-flow, new blocks may be created. 1464 if (Stmt* C = F->getCond()) { 1465 Block = ExitConditionBlock; 1466 EntryConditionBlock = addStmt(C); 1467 assert(Block == EntryConditionBlock || 1468 (Block == 0 && EntryConditionBlock == Succ)); 1469 1470 // If this block contains a condition variable, add both the condition 1471 // variable and initializer to the CFG. 1472 if (VarDecl *VD = F->getConditionVariable()) { 1473 if (Expr *Init = VD->getInit()) { 1474 autoCreateBlock(); 1475 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 1476 EntryConditionBlock = addStmt(Init); 1477 assert(Block == EntryConditionBlock); 1478 } 1479 } 1480 1481 if (Block) { 1482 if (badCFG) 1483 return 0; 1484 } 1485 } 1486 1487 // The condition block is the implicit successor for the loop body as well as 1488 // any code above the loop. 1489 Succ = EntryConditionBlock; 1490 1491 // See if this is a known constant. 1492 TryResult KnownVal(true); 1493 1494 if (F->getCond()) 1495 KnownVal = TryEvaluateBool(F->getCond()); 1496 1497 // Now create the loop body. 1498 { 1499 assert(F->getBody()); 1500 1501 // Save the current values for Block, Succ, and continue targets. 1502 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ); 1503 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget); 1504 1505 // Create a new block to contain the (bottom) of the loop body. 1506 Block = NULL; 1507 1508 // Loop body should end with destructor of Condition variable (if any). 1509 addAutomaticObjDtors(ScopePos, LoopBeginScopePos, F); 1510 1511 if (Stmt* I = F->getInc()) { 1512 // Generate increment code in its own basic block. This is the target of 1513 // continue statements. 1514 Succ = addStmt(I); 1515 } else { 1516 // No increment code. Create a special, empty, block that is used as the 1517 // target block for "looping back" to the start of the loop. 1518 assert(Succ == EntryConditionBlock); 1519 Succ = Block ? Block : createBlock(); 1520 } 1521 1522 // Finish up the increment (or empty) block if it hasn't been already. 1523 if (Block) { 1524 assert(Block == Succ); 1525 if (badCFG) 1526 return 0; 1527 Block = 0; 1528 } 1529 1530 ContinueJumpTarget = JumpTarget(Succ, ContinueScopePos); 1531 1532 // The starting block for the loop increment is the block that should 1533 // represent the 'loop target' for looping back to the start of the loop. 1534 ContinueJumpTarget.Block->setLoopTarget(F); 1535 1536 // If body is not a compound statement create implicit scope 1537 // and add destructors. 1538 if (!isa<CompoundStmt>(F->getBody())) 1539 addLocalScopeAndDtors(F->getBody()); 1540 1541 // Now populate the body block, and in the process create new blocks as we 1542 // walk the body of the loop. 1543 CFGBlock* BodyBlock = addStmt(F->getBody()); 1544 1545 if (!BodyBlock) 1546 BodyBlock = ContinueJumpTarget.Block;//can happen for "for (...;...;...);" 1547 else if (badCFG) 1548 return 0; 1549 1550 // This new body block is a successor to our "exit" condition block. 1551 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1552 } 1553 1554 // Link up the condition block with the code that follows the loop. (the 1555 // false branch). 1556 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1557 1558 // If the loop contains initialization, create a new block for those 1559 // statements. This block can also contain statements that precede the loop. 1560 if (Stmt* I = F->getInit()) { 1561 Block = createBlock(); 1562 return addStmt(I); 1563 } else { 1564 // There is no loop initialization. We are thus basically a while loop. 1565 // NULL out Block to force lazy block construction. 1566 Block = NULL; 1567 Succ = EntryConditionBlock; 1568 return EntryConditionBlock; 1569 } 1570} 1571 1572CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) { 1573 if (asc.alwaysAdd()) { 1574 autoCreateBlock(); 1575 AppendStmt(Block, M, asc); 1576 } 1577 return Visit(M->getBase(), 1578 M->isArrow() ? AddStmtChoice::NotAlwaysAdd 1579 : AddStmtChoice::AsLValueNotAlwaysAdd); 1580} 1581 1582CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1583 // Objective-C fast enumeration 'for' statements: 1584 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1585 // 1586 // for ( Type newVariable in collection_expression ) { statements } 1587 // 1588 // becomes: 1589 // 1590 // prologue: 1591 // 1. collection_expression 1592 // T. jump to loop_entry 1593 // loop_entry: 1594 // 1. side-effects of element expression 1595 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1596 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1597 // TB: 1598 // statements 1599 // T. jump to loop_entry 1600 // FB: 1601 // what comes after 1602 // 1603 // and 1604 // 1605 // Type existingItem; 1606 // for ( existingItem in expression ) { statements } 1607 // 1608 // becomes: 1609 // 1610 // the same with newVariable replaced with existingItem; the binding works 1611 // the same except that for one ObjCForCollectionStmt::getElement() returns 1612 // a DeclStmt and the other returns a DeclRefExpr. 1613 // 1614 1615 CFGBlock* LoopSuccessor = 0; 1616 1617 if (Block) { 1618 if (badCFG) 1619 return 0; 1620 LoopSuccessor = Block; 1621 Block = 0; 1622 } else 1623 LoopSuccessor = Succ; 1624 1625 // Build the condition blocks. 1626 CFGBlock* ExitConditionBlock = createBlock(false); 1627 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1628 1629 // Set the terminator for the "exit" condition block. 1630 ExitConditionBlock->setTerminator(S); 1631 1632 // The last statement in the block should be the ObjCForCollectionStmt, which 1633 // performs the actual binding to 'element' and determines if there are any 1634 // more items in the collection. 1635 AppendStmt(ExitConditionBlock, S); 1636 Block = ExitConditionBlock; 1637 1638 // Walk the 'element' expression to see if there are any side-effects. We 1639 // generate new blocks as necesary. We DON'T add the statement by default to 1640 // the CFG unless it contains control-flow. 1641 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1642 if (Block) { 1643 if (badCFG) 1644 return 0; 1645 Block = 0; 1646 } 1647 1648 // The condition block is the implicit successor for the loop body as well as 1649 // any code above the loop. 1650 Succ = EntryConditionBlock; 1651 1652 // Now create the true branch. 1653 { 1654 // Save the current values for Succ, continue and break targets. 1655 SaveAndRestore<CFGBlock*> save_Succ(Succ); 1656 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget), 1657 save_break(BreakJumpTarget); 1658 1659 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 1660 ContinueJumpTarget = JumpTarget(EntryConditionBlock, ScopePos); 1661 1662 CFGBlock* BodyBlock = addStmt(S->getBody()); 1663 1664 if (!BodyBlock) 1665 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1666 else if (Block) { 1667 if (badCFG) 1668 return 0; 1669 } 1670 1671 // This new body block is a successor to our "exit" condition block. 1672 AddSuccessor(ExitConditionBlock, BodyBlock); 1673 } 1674 1675 // Link up the condition block with the code that follows the loop. 1676 // (the false branch). 1677 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1678 1679 // Now create a prologue block to contain the collection expression. 1680 Block = createBlock(); 1681 return addStmt(S->getCollection()); 1682} 1683 1684CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1685 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1686 1687 // Inline the body. 1688 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1689 1690 // The sync body starts its own basic block. This makes it a little easier 1691 // for diagnostic clients. 1692 if (SyncBlock) { 1693 if (badCFG) 1694 return 0; 1695 1696 Block = 0; 1697 Succ = SyncBlock; 1698 } 1699 1700 // Add the @synchronized to the CFG. 1701 autoCreateBlock(); 1702 AppendStmt(Block, S, AddStmtChoice::AlwaysAdd); 1703 1704 // Inline the sync expression. 1705 return addStmt(S->getSynchExpr()); 1706} 1707 1708CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1709 // FIXME 1710 return NYS(); 1711} 1712 1713CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1714 CFGBlock* LoopSuccessor = NULL; 1715 1716 // Save local scope position because in case of condition variable ScopePos 1717 // won't be restored when traversing AST. 1718 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 1719 1720 // Create local scope for possible condition variable. 1721 // Store scope position for continue statement. 1722 LocalScope::const_iterator LoopBeginScopePos = ScopePos; 1723 if (VarDecl* VD = W->getConditionVariable()) { 1724 addLocalScopeForVarDecl(VD); 1725 addAutomaticObjDtors(ScopePos, LoopBeginScopePos, W); 1726 } 1727 1728 // "while" is a control-flow statement. Thus we stop processing the current 1729 // block. 1730 if (Block) { 1731 if (badCFG) 1732 return 0; 1733 LoopSuccessor = Block; 1734 } else 1735 LoopSuccessor = Succ; 1736 1737 // Because of short-circuit evaluation, the condition of the loop can span 1738 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1739 // evaluate the condition. 1740 CFGBlock* ExitConditionBlock = createBlock(false); 1741 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1742 1743 // Set the terminator for the "exit" condition block. 1744 ExitConditionBlock->setTerminator(W); 1745 1746 // Now add the actual condition to the condition block. Because the condition 1747 // itself may contain control-flow, new blocks may be created. Thus we update 1748 // "Succ" after adding the condition. 1749 if (Stmt* C = W->getCond()) { 1750 Block = ExitConditionBlock; 1751 EntryConditionBlock = addStmt(C); 1752 // The condition might finish the current 'Block'. 1753 Block = EntryConditionBlock; 1754 1755 // If this block contains a condition variable, add both the condition 1756 // variable and initializer to the CFG. 1757 if (VarDecl *VD = W->getConditionVariable()) { 1758 if (Expr *Init = VD->getInit()) { 1759 autoCreateBlock(); 1760 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1761 EntryConditionBlock = addStmt(Init); 1762 assert(Block == EntryConditionBlock); 1763 } 1764 } 1765 1766 if (Block) { 1767 if (badCFG) 1768 return 0; 1769 } 1770 } 1771 1772 // The condition block is the implicit successor for the loop body as well as 1773 // any code above the loop. 1774 Succ = EntryConditionBlock; 1775 1776 // See if this is a known constant. 1777 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1778 1779 // Process the loop body. 1780 { 1781 assert(W->getBody()); 1782 1783 // Save the current values for Block, Succ, and continue and break targets 1784 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ); 1785 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget), 1786 save_break(BreakJumpTarget); 1787 1788 // Create an empty block to represent the transition block for looping back 1789 // to the head of the loop. 1790 Block = 0; 1791 assert(Succ == EntryConditionBlock); 1792 Succ = createBlock(); 1793 Succ->setLoopTarget(W); 1794 ContinueJumpTarget = JumpTarget(Succ, LoopBeginScopePos); 1795 1796 // All breaks should go to the code following the loop. 1797 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 1798 1799 // NULL out Block to force lazy instantiation of blocks for the body. 1800 Block = NULL; 1801 1802 // Loop body should end with destructor of Condition variable (if any). 1803 addAutomaticObjDtors(ScopePos, LoopBeginScopePos, W); 1804 1805 // If body is not a compound statement create implicit scope 1806 // and add destructors. 1807 if (!isa<CompoundStmt>(W->getBody())) 1808 addLocalScopeAndDtors(W->getBody()); 1809 1810 // Create the body. The returned block is the entry to the loop body. 1811 CFGBlock* BodyBlock = addStmt(W->getBody()); 1812 1813 if (!BodyBlock) 1814 BodyBlock = ContinueJumpTarget.Block; // can happen for "while(...) ;" 1815 else if (Block) { 1816 if (badCFG) 1817 return 0; 1818 } 1819 1820 // Add the loop body entry as a successor to the condition. 1821 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1822 } 1823 1824 // Link up the condition block with the code that follows the loop. (the 1825 // false branch). 1826 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1827 1828 // There can be no more statements in the condition block since we loop back 1829 // to this block. NULL out Block to force lazy creation of another block. 1830 Block = NULL; 1831 1832 // Return the condition block, which is the dominating block for the loop. 1833 Succ = EntryConditionBlock; 1834 return EntryConditionBlock; 1835} 1836 1837 1838CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1839 // FIXME: For now we pretend that @catch and the code it contains does not 1840 // exit. 1841 return Block; 1842} 1843 1844CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1845 // FIXME: This isn't complete. We basically treat @throw like a return 1846 // statement. 1847 1848 // If we were in the middle of a block we stop processing that block. 1849 if (badCFG) 1850 return 0; 1851 1852 // Create the new block. 1853 Block = createBlock(false); 1854 1855 // The Exit block is the only successor. 1856 AddSuccessor(Block, &cfg->getExit()); 1857 1858 // Add the statement to the block. This may create new blocks if S contains 1859 // control-flow (short-circuit operations). 1860 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1861} 1862 1863CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1864 // If we were in the middle of a block we stop processing that block. 1865 if (badCFG) 1866 return 0; 1867 1868 // Create the new block. 1869 Block = createBlock(false); 1870 1871 if (TryTerminatedBlock) 1872 // The current try statement is the only successor. 1873 AddSuccessor(Block, TryTerminatedBlock); 1874 else 1875 // otherwise the Exit block is the only successor. 1876 AddSuccessor(Block, &cfg->getExit()); 1877 1878 // Add the statement to the block. This may create new blocks if S contains 1879 // control-flow (short-circuit operations). 1880 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1881} 1882 1883CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1884 CFGBlock* LoopSuccessor = NULL; 1885 1886 // "do...while" is a control-flow statement. Thus we stop processing the 1887 // current block. 1888 if (Block) { 1889 if (badCFG) 1890 return 0; 1891 LoopSuccessor = Block; 1892 } else 1893 LoopSuccessor = Succ; 1894 1895 // Because of short-circuit evaluation, the condition of the loop can span 1896 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1897 // evaluate the condition. 1898 CFGBlock* ExitConditionBlock = createBlock(false); 1899 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1900 1901 // Set the terminator for the "exit" condition block. 1902 ExitConditionBlock->setTerminator(D); 1903 1904 // Now add the actual condition to the condition block. Because the condition 1905 // itself may contain control-flow, new blocks may be created. 1906 if (Stmt* C = D->getCond()) { 1907 Block = ExitConditionBlock; 1908 EntryConditionBlock = addStmt(C); 1909 if (Block) { 1910 if (badCFG) 1911 return 0; 1912 } 1913 } 1914 1915 // The condition block is the implicit successor for the loop body. 1916 Succ = EntryConditionBlock; 1917 1918 // See if this is a known constant. 1919 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1920 1921 // Process the loop body. 1922 CFGBlock* BodyBlock = NULL; 1923 { 1924 assert(D->getBody()); 1925 1926 // Save the current values for Block, Succ, and continue and break targets 1927 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ); 1928 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget), 1929 save_break(BreakJumpTarget); 1930 1931 // All continues within this loop should go to the condition block 1932 ContinueJumpTarget = JumpTarget(EntryConditionBlock, ScopePos); 1933 1934 // All breaks should go to the code following the loop. 1935 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 1936 1937 // NULL out Block to force lazy instantiation of blocks for the body. 1938 Block = NULL; 1939 1940 // If body is not a compound statement create implicit scope 1941 // and add destructors. 1942 if (!isa<CompoundStmt>(D->getBody())) 1943 addLocalScopeAndDtors(D->getBody()); 1944 1945 // Create the body. The returned block is the entry to the loop body. 1946 BodyBlock = addStmt(D->getBody()); 1947 1948 if (!BodyBlock) 1949 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1950 else if (Block) { 1951 if (badCFG) 1952 return 0; 1953 } 1954 1955 if (!KnownVal.isFalse()) { 1956 // Add an intermediate block between the BodyBlock and the 1957 // ExitConditionBlock to represent the "loop back" transition. Create an 1958 // empty block to represent the transition block for looping back to the 1959 // head of the loop. 1960 // FIXME: Can we do this more efficiently without adding another block? 1961 Block = NULL; 1962 Succ = BodyBlock; 1963 CFGBlock *LoopBackBlock = createBlock(); 1964 LoopBackBlock->setLoopTarget(D); 1965 1966 // Add the loop body entry as a successor to the condition. 1967 AddSuccessor(ExitConditionBlock, LoopBackBlock); 1968 } 1969 else 1970 AddSuccessor(ExitConditionBlock, NULL); 1971 } 1972 1973 // Link up the condition block with the code that follows the loop. 1974 // (the false branch). 1975 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1976 1977 // There can be no more statements in the body block(s) since we loop back to 1978 // the body. NULL out Block to force lazy creation of another block. 1979 Block = NULL; 1980 1981 // Return the loop body, which is the dominating block for the loop. 1982 Succ = BodyBlock; 1983 return BodyBlock; 1984} 1985 1986CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1987 // "continue" is a control-flow statement. Thus we stop processing the 1988 // current block. 1989 if (badCFG) 1990 return 0; 1991 1992 // Now create a new block that ends with the continue statement. 1993 Block = createBlock(false); 1994 Block->setTerminator(C); 1995 1996 // If there is no target for the continue, then we are looking at an 1997 // incomplete AST. This means the CFG cannot be constructed. 1998 if (ContinueJumpTarget.Block) { 1999 addAutomaticObjDtors(ScopePos, ContinueJumpTarget.ScopePos, C); 2000 AddSuccessor(Block, ContinueJumpTarget.Block); 2001 } else 2002 badCFG = true; 2003 2004 return Block; 2005} 2006 2007CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 2008 AddStmtChoice asc) { 2009 2010 if (asc.alwaysAdd()) { 2011 autoCreateBlock(); 2012 AppendStmt(Block, E); 2013 } 2014 2015 // VLA types have expressions that must be evaluated. 2016 if (E->isArgumentType()) { 2017 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 2018 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 2019 addStmt(VA->getSizeExpr()); 2020 } 2021 2022 return Block; 2023} 2024 2025/// VisitStmtExpr - Utility method to handle (nested) statement 2026/// expressions (a GCC extension). 2027CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 2028 if (asc.alwaysAdd()) { 2029 autoCreateBlock(); 2030 AppendStmt(Block, SE); 2031 } 2032 return VisitCompoundStmt(SE->getSubStmt()); 2033} 2034 2035CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 2036 // "switch" is a control-flow statement. Thus we stop processing the current 2037 // block. 2038 CFGBlock* SwitchSuccessor = NULL; 2039 2040 // Save local scope position because in case of condition variable ScopePos 2041 // won't be restored when traversing AST. 2042 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 2043 2044 // Create local scope for possible condition variable. 2045 // Store scope position. Add implicit destructor. 2046 if (VarDecl* VD = Terminator->getConditionVariable()) { 2047 LocalScope::const_iterator SwitchBeginScopePos = ScopePos; 2048 addLocalScopeForVarDecl(VD); 2049 addAutomaticObjDtors(ScopePos, SwitchBeginScopePos, Terminator); 2050 } 2051 2052 if (Block) { 2053 if (badCFG) 2054 return 0; 2055 SwitchSuccessor = Block; 2056 } else SwitchSuccessor = Succ; 2057 2058 // Save the current "switch" context. 2059 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 2060 save_default(DefaultCaseBlock); 2061 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget); 2062 2063 // Set the "default" case to be the block after the switch statement. If the 2064 // switch statement contains a "default:", this value will be overwritten with 2065 // the block for that code. 2066 DefaultCaseBlock = SwitchSuccessor; 2067 2068 // Create a new block that will contain the switch statement. 2069 SwitchTerminatedBlock = createBlock(false); 2070 2071 // Now process the switch body. The code after the switch is the implicit 2072 // successor. 2073 Succ = SwitchSuccessor; 2074 BreakJumpTarget = JumpTarget(SwitchSuccessor, ScopePos); 2075 2076 // When visiting the body, the case statements should automatically get linked 2077 // up to the switch. We also don't keep a pointer to the body, since all 2078 // control-flow from the switch goes to case/default statements. 2079 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 2080 Block = NULL; 2081 2082 // If body is not a compound statement create implicit scope 2083 // and add destructors. 2084 if (!isa<CompoundStmt>(Terminator->getBody())) 2085 addLocalScopeAndDtors(Terminator->getBody()); 2086 2087 addStmt(Terminator->getBody()); 2088 if (Block) { 2089 if (badCFG) 2090 return 0; 2091 } 2092 2093 // If we have no "default:" case, the default transition is to the code 2094 // following the switch body. 2095 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 2096 2097 // Add the terminator and condition in the switch block. 2098 SwitchTerminatedBlock->setTerminator(Terminator); 2099 assert(Terminator->getCond() && "switch condition must be non-NULL"); 2100 Block = SwitchTerminatedBlock; 2101 Block = addStmt(Terminator->getCond()); 2102 2103 // Finally, if the SwitchStmt contains a condition variable, add both the 2104 // SwitchStmt and the condition variable initialization to the CFG. 2105 if (VarDecl *VD = Terminator->getConditionVariable()) { 2106 if (Expr *Init = VD->getInit()) { 2107 autoCreateBlock(); 2108 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 2109 addStmt(Init); 2110 } 2111 } 2112 2113 return Block; 2114} 2115 2116CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 2117 // CaseStmts are essentially labels, so they are the first statement in a 2118 // block. 2119 CFGBlock *TopBlock = 0, *LastBlock = 0; 2120 2121 if (Stmt *Sub = CS->getSubStmt()) { 2122 // For deeply nested chains of CaseStmts, instead of doing a recursion 2123 // (which can blow out the stack), manually unroll and create blocks 2124 // along the way. 2125 while (isa<CaseStmt>(Sub)) { 2126 CFGBlock *CurrentBlock = createBlock(false); 2127 CurrentBlock->setLabel(CS); 2128 2129 if (TopBlock) 2130 AddSuccessor(LastBlock, CurrentBlock); 2131 else 2132 TopBlock = CurrentBlock; 2133 2134 AddSuccessor(SwitchTerminatedBlock, CurrentBlock); 2135 LastBlock = CurrentBlock; 2136 2137 CS = cast<CaseStmt>(Sub); 2138 Sub = CS->getSubStmt(); 2139 } 2140 2141 addStmt(Sub); 2142 } 2143 2144 CFGBlock* CaseBlock = Block; 2145 if (!CaseBlock) 2146 CaseBlock = createBlock(); 2147 2148 // Cases statements partition blocks, so this is the top of the basic block we 2149 // were processing (the "case XXX:" is the label). 2150 CaseBlock->setLabel(CS); 2151 2152 if (badCFG) 2153 return 0; 2154 2155 // Add this block to the list of successors for the block with the switch 2156 // statement. 2157 assert(SwitchTerminatedBlock); 2158 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 2159 2160 // We set Block to NULL to allow lazy creation of a new block (if necessary) 2161 Block = NULL; 2162 2163 if (TopBlock) { 2164 AddSuccessor(LastBlock, CaseBlock); 2165 Succ = TopBlock; 2166 } 2167 else { 2168 // This block is now the implicit successor of other blocks. 2169 Succ = CaseBlock; 2170 } 2171 2172 return Succ; 2173} 2174 2175CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 2176 if (Terminator->getSubStmt()) 2177 addStmt(Terminator->getSubStmt()); 2178 2179 DefaultCaseBlock = Block; 2180 2181 if (!DefaultCaseBlock) 2182 DefaultCaseBlock = createBlock(); 2183 2184 // Default statements partition blocks, so this is the top of the basic block 2185 // we were processing (the "default:" is the label). 2186 DefaultCaseBlock->setLabel(Terminator); 2187 2188 if (badCFG) 2189 return 0; 2190 2191 // Unlike case statements, we don't add the default block to the successors 2192 // for the switch statement immediately. This is done when we finish 2193 // processing the switch statement. This allows for the default case 2194 // (including a fall-through to the code after the switch statement) to always 2195 // be the last successor of a switch-terminated block. 2196 2197 // We set Block to NULL to allow lazy creation of a new block (if necessary) 2198 Block = NULL; 2199 2200 // This block is now the implicit successor of other blocks. 2201 Succ = DefaultCaseBlock; 2202 2203 return DefaultCaseBlock; 2204} 2205 2206CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 2207 // "try"/"catch" is a control-flow statement. Thus we stop processing the 2208 // current block. 2209 CFGBlock* TrySuccessor = NULL; 2210 2211 if (Block) { 2212 if (badCFG) 2213 return 0; 2214 TrySuccessor = Block; 2215 } else TrySuccessor = Succ; 2216 2217 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 2218 2219 // Create a new block that will contain the try statement. 2220 CFGBlock *NewTryTerminatedBlock = createBlock(false); 2221 // Add the terminator in the try block. 2222 NewTryTerminatedBlock->setTerminator(Terminator); 2223 2224 bool HasCatchAll = false; 2225 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 2226 // The code after the try is the implicit successor. 2227 Succ = TrySuccessor; 2228 CXXCatchStmt *CS = Terminator->getHandler(h); 2229 if (CS->getExceptionDecl() == 0) { 2230 HasCatchAll = true; 2231 } 2232 Block = NULL; 2233 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 2234 if (CatchBlock == 0) 2235 return 0; 2236 // Add this block to the list of successors for the block with the try 2237 // statement. 2238 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 2239 } 2240 if (!HasCatchAll) { 2241 if (PrevTryTerminatedBlock) 2242 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 2243 else 2244 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 2245 } 2246 2247 // The code after the try is the implicit successor. 2248 Succ = TrySuccessor; 2249 2250 // Save the current "try" context. 2251 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 2252 TryTerminatedBlock = NewTryTerminatedBlock; 2253 2254 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 2255 Block = NULL; 2256 Block = addStmt(Terminator->getTryBlock()); 2257 return Block; 2258} 2259 2260CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 2261 // CXXCatchStmt are treated like labels, so they are the first statement in a 2262 // block. 2263 2264 // Save local scope position because in case of exception variable ScopePos 2265 // won't be restored when traversing AST. 2266 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 2267 2268 // Create local scope for possible exception variable. 2269 // Store scope position. Add implicit destructor. 2270 if (VarDecl* VD = CS->getExceptionDecl()) { 2271 LocalScope::const_iterator BeginScopePos = ScopePos; 2272 addLocalScopeForVarDecl(VD); 2273 addAutomaticObjDtors(ScopePos, BeginScopePos, CS); 2274 } 2275 2276 if (CS->getHandlerBlock()) 2277 addStmt(CS->getHandlerBlock()); 2278 2279 CFGBlock* CatchBlock = Block; 2280 if (!CatchBlock) 2281 CatchBlock = createBlock(); 2282 2283 CatchBlock->setLabel(CS); 2284 2285 if (badCFG) 2286 return 0; 2287 2288 // We set Block to NULL to allow lazy creation of a new block (if necessary) 2289 Block = NULL; 2290 2291 return CatchBlock; 2292} 2293 2294CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C, 2295 AddStmtChoice asc) { 2296 AddStmtChoice::Kind K = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 2297 : AddStmtChoice::AlwaysAdd; 2298 autoCreateBlock(); 2299 AppendStmt(Block, C, AddStmtChoice(K)); 2300 return VisitChildren(C); 2301} 2302 2303CFGBlock *CFGBuilder::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C, 2304 AddStmtChoice asc) { 2305 AddStmtChoice::Kind K = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 2306 : AddStmtChoice::AlwaysAdd; 2307 autoCreateBlock(); 2308 AppendStmt(Block, C, AddStmtChoice(K)); 2309 return VisitChildren(C); 2310} 2311 2312CFGBlock *CFGBuilder::VisitCXXMemberCallExpr(CXXMemberCallExpr *C, 2313 AddStmtChoice asc) { 2314 AddStmtChoice::Kind K = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 2315 : AddStmtChoice::AlwaysAdd; 2316 autoCreateBlock(); 2317 AppendStmt(Block, C, AddStmtChoice(K)); 2318 return VisitChildren(C); 2319} 2320 2321CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 2322 // Lazily create the indirect-goto dispatch block if there isn't one already. 2323 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 2324 2325 if (!IBlock) { 2326 IBlock = createBlock(false); 2327 cfg->setIndirectGotoBlock(IBlock); 2328 } 2329 2330 // IndirectGoto is a control-flow statement. Thus we stop processing the 2331 // current block and create a new one. 2332 if (badCFG) 2333 return 0; 2334 2335 Block = createBlock(false); 2336 Block->setTerminator(I); 2337 AddSuccessor(Block, IBlock); 2338 return addStmt(I->getTarget()); 2339} 2340 2341} // end anonymous namespace 2342 2343/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 2344/// no successors or predecessors. If this is the first block created in the 2345/// CFG, it is automatically set to be the Entry and Exit of the CFG. 2346CFGBlock* CFG::createBlock() { 2347 bool first_block = begin() == end(); 2348 2349 // Create the block. 2350 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 2351 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 2352 Blocks.push_back(Mem, BlkBVC); 2353 2354 // If this is the first block, set it as the Entry and Exit. 2355 if (first_block) 2356 Entry = Exit = &back(); 2357 2358 // Return the block. 2359 return &back(); 2360} 2361 2362/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 2363/// CFG is returned to the caller. 2364CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 2365 BuildOptions BO) { 2366 CFGBuilder Builder; 2367 return Builder.buildCFG(D, Statement, C, BO); 2368} 2369 2370//===----------------------------------------------------------------------===// 2371// CFG: Queries for BlkExprs. 2372//===----------------------------------------------------------------------===// 2373 2374namespace { 2375 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 2376} 2377 2378static void FindSubExprAssignments(Stmt *S, 2379 llvm::SmallPtrSet<Expr*,50>& Set) { 2380 if (!S) 2381 return; 2382 2383 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 2384 Stmt *child = *I; 2385 if (!child) 2386 continue; 2387 2388 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 2389 if (B->isAssignmentOp()) Set.insert(B); 2390 2391 FindSubExprAssignments(child, Set); 2392 } 2393} 2394 2395static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 2396 BlkExprMapTy* M = new BlkExprMapTy(); 2397 2398 // Look for assignments that are used as subexpressions. These are the only 2399 // assignments that we want to *possibly* register as a block-level 2400 // expression. Basically, if an assignment occurs both in a subexpression and 2401 // at the block-level, it is a block-level expression. 2402 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 2403 2404 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 2405 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 2406 if (CFGStmt S = BI->getAs<CFGStmt>()) 2407 FindSubExprAssignments(S, SubExprAssignments); 2408 2409 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 2410 2411 // Iterate over the statements again on identify the Expr* and Stmt* at the 2412 // block-level that are block-level expressions. 2413 2414 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) { 2415 CFGStmt CS = BI->getAs<CFGStmt>(); 2416 if (!CS.isValid()) 2417 continue; 2418 if (Expr* Exp = dyn_cast<Expr>(CS.getStmt())) { 2419 2420 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 2421 // Assignment expressions that are not nested within another 2422 // expression are really "statements" whose value is never used by 2423 // another expression. 2424 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 2425 continue; 2426 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 2427 // Special handling for statement expressions. The last statement in 2428 // the statement expression is also a block-level expr. 2429 const CompoundStmt* C = Terminator->getSubStmt(); 2430 if (!C->body_empty()) { 2431 unsigned x = M->size(); 2432 (*M)[C->body_back()] = x; 2433 } 2434 } 2435 2436 unsigned x = M->size(); 2437 (*M)[Exp] = x; 2438 } 2439 } 2440 2441 // Look at terminators. The condition is a block-level expression. 2442 2443 Stmt* S = (*I)->getTerminatorCondition(); 2444 2445 if (S && M->find(S) == M->end()) { 2446 unsigned x = M->size(); 2447 (*M)[S] = x; 2448 } 2449 } 2450 2451 return M; 2452} 2453 2454CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 2455 assert(S != NULL); 2456 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 2457 2458 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 2459 BlkExprMapTy::iterator I = M->find(S); 2460 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 2461} 2462 2463unsigned CFG::getNumBlkExprs() { 2464 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 2465 return M->size(); 2466 else { 2467 // We assume callers interested in the number of BlkExprs will want 2468 // the map constructed if it doesn't already exist. 2469 BlkExprMap = (void*) PopulateBlkExprMap(*this); 2470 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 2471 } 2472} 2473 2474//===----------------------------------------------------------------------===// 2475// Filtered walking of the CFG. 2476//===----------------------------------------------------------------------===// 2477 2478bool CFGBlock::FilterEdge(const CFGBlock::FilterOptions &F, 2479 const CFGBlock *From, const CFGBlock *To) { 2480 2481 if (F.IgnoreDefaultsWithCoveredEnums) { 2482 // If the 'To' has no label or is labeled but the label isn't a 2483 // CaseStmt then filter this edge. 2484 if (const SwitchStmt *S = 2485 dyn_cast_or_null<SwitchStmt>(From->getTerminator().getStmt())) { 2486 if (S->isAllEnumCasesCovered()) { 2487 const Stmt *L = To->getLabel(); 2488 if (!L || !isa<CaseStmt>(L)) 2489 return true; 2490 } 2491 } 2492 } 2493 2494 return false; 2495} 2496 2497//===----------------------------------------------------------------------===// 2498// Cleanup: CFG dstor. 2499//===----------------------------------------------------------------------===// 2500 2501CFG::~CFG() { 2502 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 2503} 2504 2505//===----------------------------------------------------------------------===// 2506// CFG pretty printing 2507//===----------------------------------------------------------------------===// 2508 2509namespace { 2510 2511class StmtPrinterHelper : public PrinterHelper { 2512 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 2513 typedef llvm::DenseMap<Decl*,std::pair<unsigned,unsigned> > DeclMapTy; 2514 StmtMapTy StmtMap; 2515 DeclMapTy DeclMap; 2516 signed CurrentBlock; 2517 unsigned CurrentStmt; 2518 const LangOptions &LangOpts; 2519public: 2520 2521 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 2522 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 2523 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 2524 unsigned j = 1; 2525 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 2526 BI != BEnd; ++BI, ++j ) { 2527 if (CFGStmt SE = BI->getAs<CFGStmt>()) { 2528 std::pair<unsigned, unsigned> P((*I)->getBlockID(), j); 2529 StmtMap[SE] = P; 2530 2531 if (DeclStmt* DS = dyn_cast<DeclStmt>(SE.getStmt())) { 2532 DeclMap[DS->getSingleDecl()] = P; 2533 2534 } else if (IfStmt* IS = dyn_cast<IfStmt>(SE.getStmt())) { 2535 if (VarDecl* VD = IS->getConditionVariable()) 2536 DeclMap[VD] = P; 2537 2538 } else if (ForStmt* FS = dyn_cast<ForStmt>(SE.getStmt())) { 2539 if (VarDecl* VD = FS->getConditionVariable()) 2540 DeclMap[VD] = P; 2541 2542 } else if (WhileStmt* WS = dyn_cast<WhileStmt>(SE.getStmt())) { 2543 if (VarDecl* VD = WS->getConditionVariable()) 2544 DeclMap[VD] = P; 2545 2546 } else if (SwitchStmt* SS = dyn_cast<SwitchStmt>(SE.getStmt())) { 2547 if (VarDecl* VD = SS->getConditionVariable()) 2548 DeclMap[VD] = P; 2549 2550 } else if (CXXCatchStmt* CS = dyn_cast<CXXCatchStmt>(SE.getStmt())) { 2551 if (VarDecl* VD = CS->getExceptionDecl()) 2552 DeclMap[VD] = P; 2553 } 2554 } 2555 } 2556 } 2557 } 2558 2559 virtual ~StmtPrinterHelper() {} 2560 2561 const LangOptions &getLangOpts() const { return LangOpts; } 2562 void setBlockID(signed i) { CurrentBlock = i; } 2563 void setStmtID(unsigned i) { CurrentStmt = i; } 2564 2565 virtual bool handledStmt(Stmt* S, llvm::raw_ostream& OS) { 2566 StmtMapTy::iterator I = StmtMap.find(S); 2567 2568 if (I == StmtMap.end()) 2569 return false; 2570 2571 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 2572 && I->second.second == CurrentStmt) { 2573 return false; 2574 } 2575 2576 OS << "[B" << I->second.first << "." << I->second.second << "]"; 2577 return true; 2578 } 2579 2580 bool handleDecl(Decl* D, llvm::raw_ostream& OS) { 2581 DeclMapTy::iterator I = DeclMap.find(D); 2582 2583 if (I == DeclMap.end()) 2584 return false; 2585 2586 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 2587 && I->second.second == CurrentStmt) { 2588 return false; 2589 } 2590 2591 OS << "[B" << I->second.first << "." << I->second.second << "]"; 2592 return true; 2593 } 2594}; 2595} // end anonymous namespace 2596 2597 2598namespace { 2599class CFGBlockTerminatorPrint 2600 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 2601 2602 llvm::raw_ostream& OS; 2603 StmtPrinterHelper* Helper; 2604 PrintingPolicy Policy; 2605public: 2606 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 2607 const PrintingPolicy &Policy) 2608 : OS(os), Helper(helper), Policy(Policy) {} 2609 2610 void VisitIfStmt(IfStmt* I) { 2611 OS << "if "; 2612 I->getCond()->printPretty(OS,Helper,Policy); 2613 } 2614 2615 // Default case. 2616 void VisitStmt(Stmt* Terminator) { 2617 Terminator->printPretty(OS, Helper, Policy); 2618 } 2619 2620 void VisitForStmt(ForStmt* F) { 2621 OS << "for (" ; 2622 if (F->getInit()) 2623 OS << "..."; 2624 OS << "; "; 2625 if (Stmt* C = F->getCond()) 2626 C->printPretty(OS, Helper, Policy); 2627 OS << "; "; 2628 if (F->getInc()) 2629 OS << "..."; 2630 OS << ")"; 2631 } 2632 2633 void VisitWhileStmt(WhileStmt* W) { 2634 OS << "while " ; 2635 if (Stmt* C = W->getCond()) 2636 C->printPretty(OS, Helper, Policy); 2637 } 2638 2639 void VisitDoStmt(DoStmt* D) { 2640 OS << "do ... while "; 2641 if (Stmt* C = D->getCond()) 2642 C->printPretty(OS, Helper, Policy); 2643 } 2644 2645 void VisitSwitchStmt(SwitchStmt* Terminator) { 2646 OS << "switch "; 2647 Terminator->getCond()->printPretty(OS, Helper, Policy); 2648 } 2649 2650 void VisitCXXTryStmt(CXXTryStmt* CS) { 2651 OS << "try ..."; 2652 } 2653 2654 void VisitConditionalOperator(ConditionalOperator* C) { 2655 C->getCond()->printPretty(OS, Helper, Policy); 2656 OS << " ? ... : ..."; 2657 } 2658 2659 void VisitChooseExpr(ChooseExpr* C) { 2660 OS << "__builtin_choose_expr( "; 2661 C->getCond()->printPretty(OS, Helper, Policy); 2662 OS << " )"; 2663 } 2664 2665 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 2666 OS << "goto *"; 2667 I->getTarget()->printPretty(OS, Helper, Policy); 2668 } 2669 2670 void VisitBinaryOperator(BinaryOperator* B) { 2671 if (!B->isLogicalOp()) { 2672 VisitExpr(B); 2673 return; 2674 } 2675 2676 B->getLHS()->printPretty(OS, Helper, Policy); 2677 2678 switch (B->getOpcode()) { 2679 case BO_LOr: 2680 OS << " || ..."; 2681 return; 2682 case BO_LAnd: 2683 OS << " && ..."; 2684 return; 2685 default: 2686 assert(false && "Invalid logical operator."); 2687 } 2688 } 2689 2690 void VisitExpr(Expr* E) { 2691 E->printPretty(OS, Helper, Policy); 2692 } 2693}; 2694} // end anonymous namespace 2695 2696static void print_elem(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2697 const CFGElement &E) { 2698 if (CFGStmt CS = E.getAs<CFGStmt>()) { 2699 Stmt *S = CS; 2700 2701 if (Helper) { 2702 2703 // special printing for statement-expressions. 2704 if (StmtExpr* SE = dyn_cast<StmtExpr>(S)) { 2705 CompoundStmt* Sub = SE->getSubStmt(); 2706 2707 if (Sub->child_begin() != Sub->child_end()) { 2708 OS << "({ ... ; "; 2709 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2710 OS << " })\n"; 2711 return; 2712 } 2713 } 2714 // special printing for comma expressions. 2715 if (BinaryOperator* B = dyn_cast<BinaryOperator>(S)) { 2716 if (B->getOpcode() == BO_Comma) { 2717 OS << "... , "; 2718 Helper->handledStmt(B->getRHS(),OS); 2719 OS << '\n'; 2720 return; 2721 } 2722 } 2723 } 2724 S->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2725 2726 if (isa<CXXOperatorCallExpr>(S)) { 2727 OS << " (OperatorCall)"; 2728 } 2729 else if (isa<CXXBindTemporaryExpr>(S)) { 2730 OS << " (BindTemporary)"; 2731 } 2732 2733 // Expressions need a newline. 2734 if (isa<Expr>(S)) 2735 OS << '\n'; 2736 2737 } else if (CFGInitializer IE = E.getAs<CFGInitializer>()) { 2738 CXXBaseOrMemberInitializer* I = IE; 2739 if (I->isBaseInitializer()) 2740 OS << I->getBaseClass()->getAsCXXRecordDecl()->getName(); 2741 else OS << I->getMember()->getName(); 2742 2743 OS << "("; 2744 if (Expr* IE = I->getInit()) 2745 IE->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2746 OS << ")"; 2747 2748 if (I->isBaseInitializer()) 2749 OS << " (Base initializer)\n"; 2750 else OS << " (Member initializer)\n"; 2751 2752 } else if (CFGAutomaticObjDtor DE = E.getAs<CFGAutomaticObjDtor>()){ 2753 VarDecl* VD = DE.getVarDecl(); 2754 Helper->handleDecl(VD, OS); 2755 2756 const Type* T = VD->getType().getTypePtr(); 2757 if (const ReferenceType* RT = T->getAs<ReferenceType>()) 2758 T = RT->getPointeeType().getTypePtr(); 2759 else if (const Type *ET = T->getArrayElementTypeNoTypeQual()) 2760 T = ET; 2761 2762 OS << ".~" << T->getAsCXXRecordDecl()->getName().str() << "()"; 2763 OS << " (Implicit destructor)\n"; 2764 2765 } else if (CFGBaseDtor BE = E.getAs<CFGBaseDtor>()) { 2766 const CXXBaseSpecifier *BS = BE.getBaseSpecifier(); 2767 OS << "~" << BS->getType()->getAsCXXRecordDecl()->getName() << "()"; 2768 OS << " (Base object destructor)\n"; 2769 2770 } else if (CFGMemberDtor ME = E.getAs<CFGMemberDtor>()) { 2771 FieldDecl *FD = ME.getFieldDecl(); 2772 2773 const Type *T = FD->getType().getTypePtr(); 2774 if (const Type *ET = T->getArrayElementTypeNoTypeQual()) 2775 T = ET; 2776 2777 OS << "this->" << FD->getName(); 2778 OS << ".~" << T->getAsCXXRecordDecl()->getName() << "()"; 2779 OS << " (Member object destructor)\n"; 2780 } 2781} 2782 2783static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2784 const CFGBlock& B, 2785 StmtPrinterHelper* Helper, bool print_edges) { 2786 2787 if (Helper) Helper->setBlockID(B.getBlockID()); 2788 2789 // Print the header. 2790 OS << "\n [ B" << B.getBlockID(); 2791 2792 if (&B == &cfg->getEntry()) 2793 OS << " (ENTRY) ]\n"; 2794 else if (&B == &cfg->getExit()) 2795 OS << " (EXIT) ]\n"; 2796 else if (&B == cfg->getIndirectGotoBlock()) 2797 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2798 else 2799 OS << " ]\n"; 2800 2801 // Print the label of this block. 2802 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2803 2804 if (print_edges) 2805 OS << " "; 2806 2807 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2808 OS << L->getName(); 2809 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2810 OS << "case "; 2811 C->getLHS()->printPretty(OS, Helper, 2812 PrintingPolicy(Helper->getLangOpts())); 2813 if (C->getRHS()) { 2814 OS << " ... "; 2815 C->getRHS()->printPretty(OS, Helper, 2816 PrintingPolicy(Helper->getLangOpts())); 2817 } 2818 } else if (isa<DefaultStmt>(Label)) 2819 OS << "default"; 2820 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2821 OS << "catch ("; 2822 if (CS->getExceptionDecl()) 2823 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2824 0); 2825 else 2826 OS << "..."; 2827 OS << ")"; 2828 2829 } else 2830 assert(false && "Invalid label statement in CFGBlock."); 2831 2832 OS << ":\n"; 2833 } 2834 2835 // Iterate through the statements in the block and print them. 2836 unsigned j = 1; 2837 2838 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2839 I != E ; ++I, ++j ) { 2840 2841 // Print the statement # in the basic block and the statement itself. 2842 if (print_edges) 2843 OS << " "; 2844 2845 OS << llvm::format("%3d", j) << ": "; 2846 2847 if (Helper) 2848 Helper->setStmtID(j); 2849 2850 print_elem(OS,Helper,*I); 2851 } 2852 2853 // Print the terminator of this block. 2854 if (B.getTerminator()) { 2855 if (print_edges) 2856 OS << " "; 2857 2858 OS << " T: "; 2859 2860 if (Helper) Helper->setBlockID(-1); 2861 2862 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2863 PrintingPolicy(Helper->getLangOpts())); 2864 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator().getStmt())); 2865 OS << '\n'; 2866 } 2867 2868 if (print_edges) { 2869 // Print the predecessors of this block. 2870 OS << " Predecessors (" << B.pred_size() << "):"; 2871 unsigned i = 0; 2872 2873 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2874 I != E; ++I, ++i) { 2875 2876 if (i == 8 || (i-8) == 0) 2877 OS << "\n "; 2878 2879 OS << " B" << (*I)->getBlockID(); 2880 } 2881 2882 OS << '\n'; 2883 2884 // Print the successors of this block. 2885 OS << " Successors (" << B.succ_size() << "):"; 2886 i = 0; 2887 2888 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2889 I != E; ++I, ++i) { 2890 2891 if (i == 8 || (i-8) % 10 == 0) 2892 OS << "\n "; 2893 2894 if (*I) 2895 OS << " B" << (*I)->getBlockID(); 2896 else 2897 OS << " NULL"; 2898 } 2899 2900 OS << '\n'; 2901 } 2902} 2903 2904 2905/// dump - A simple pretty printer of a CFG that outputs to stderr. 2906void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2907 2908/// print - A simple pretty printer of a CFG that outputs to an ostream. 2909void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2910 StmtPrinterHelper Helper(this, LO); 2911 2912 // Print the entry block. 2913 print_block(OS, this, getEntry(), &Helper, true); 2914 2915 // Iterate through the CFGBlocks and print them one by one. 2916 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2917 // Skip the entry block, because we already printed it. 2918 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2919 continue; 2920 2921 print_block(OS, this, **I, &Helper, true); 2922 } 2923 2924 // Print the exit block. 2925 print_block(OS, this, getExit(), &Helper, true); 2926 OS.flush(); 2927} 2928 2929/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2930void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2931 print(llvm::errs(), cfg, LO); 2932} 2933 2934/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2935/// Generally this will only be called from CFG::print. 2936void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2937 const LangOptions &LO) const { 2938 StmtPrinterHelper Helper(cfg, LO); 2939 print_block(OS, cfg, *this, &Helper, true); 2940} 2941 2942/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2943void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2944 const LangOptions &LO) const { 2945 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2946 TPrinter.Visit(const_cast<Stmt*>(getTerminator().getStmt())); 2947} 2948 2949Stmt* CFGBlock::getTerminatorCondition() { 2950 Stmt *Terminator = this->Terminator; 2951 if (!Terminator) 2952 return NULL; 2953 2954 Expr* E = NULL; 2955 2956 switch (Terminator->getStmtClass()) { 2957 default: 2958 break; 2959 2960 case Stmt::ForStmtClass: 2961 E = cast<ForStmt>(Terminator)->getCond(); 2962 break; 2963 2964 case Stmt::WhileStmtClass: 2965 E = cast<WhileStmt>(Terminator)->getCond(); 2966 break; 2967 2968 case Stmt::DoStmtClass: 2969 E = cast<DoStmt>(Terminator)->getCond(); 2970 break; 2971 2972 case Stmt::IfStmtClass: 2973 E = cast<IfStmt>(Terminator)->getCond(); 2974 break; 2975 2976 case Stmt::ChooseExprClass: 2977 E = cast<ChooseExpr>(Terminator)->getCond(); 2978 break; 2979 2980 case Stmt::IndirectGotoStmtClass: 2981 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2982 break; 2983 2984 case Stmt::SwitchStmtClass: 2985 E = cast<SwitchStmt>(Terminator)->getCond(); 2986 break; 2987 2988 case Stmt::ConditionalOperatorClass: 2989 E = cast<ConditionalOperator>(Terminator)->getCond(); 2990 break; 2991 2992 case Stmt::BinaryOperatorClass: // '&&' and '||' 2993 E = cast<BinaryOperator>(Terminator)->getLHS(); 2994 break; 2995 2996 case Stmt::ObjCForCollectionStmtClass: 2997 return Terminator; 2998 } 2999 3000 return E ? E->IgnoreParens() : NULL; 3001} 3002 3003bool CFGBlock::hasBinaryBranchTerminator() const { 3004 const Stmt *Terminator = this->Terminator; 3005 if (!Terminator) 3006 return false; 3007 3008 Expr* E = NULL; 3009 3010 switch (Terminator->getStmtClass()) { 3011 default: 3012 return false; 3013 3014 case Stmt::ForStmtClass: 3015 case Stmt::WhileStmtClass: 3016 case Stmt::DoStmtClass: 3017 case Stmt::IfStmtClass: 3018 case Stmt::ChooseExprClass: 3019 case Stmt::ConditionalOperatorClass: 3020 case Stmt::BinaryOperatorClass: 3021 return true; 3022 } 3023 3024 return E ? E->IgnoreParens() : NULL; 3025} 3026 3027 3028//===----------------------------------------------------------------------===// 3029// CFG Graphviz Visualization 3030//===----------------------------------------------------------------------===// 3031 3032 3033#ifndef NDEBUG 3034static StmtPrinterHelper* GraphHelper; 3035#endif 3036 3037void CFG::viewCFG(const LangOptions &LO) const { 3038#ifndef NDEBUG 3039 StmtPrinterHelper H(this, LO); 3040 GraphHelper = &H; 3041 llvm::ViewGraph(this,"CFG"); 3042 GraphHelper = NULL; 3043#endif 3044} 3045 3046namespace llvm { 3047template<> 3048struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 3049 3050 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 3051 3052 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 3053 3054#ifndef NDEBUG 3055 std::string OutSStr; 3056 llvm::raw_string_ostream Out(OutSStr); 3057 print_block(Out,Graph, *Node, GraphHelper, false); 3058 std::string& OutStr = Out.str(); 3059 3060 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 3061 3062 // Process string output to make it nicer... 3063 for (unsigned i = 0; i != OutStr.length(); ++i) 3064 if (OutStr[i] == '\n') { // Left justify 3065 OutStr[i] = '\\'; 3066 OutStr.insert(OutStr.begin()+i+1, 'l'); 3067 } 3068 3069 return OutStr; 3070#else 3071 return ""; 3072#endif 3073 } 3074}; 3075} // end namespace llvm 3076