CFG.cpp revision 334c19566104d3333cf662f0017088a18eddfa81
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/// CFGBuilder - This class implements CFG construction from an AST. 56/// The builder is stateful: an instance of the builder should be used to only 57/// construct a single CFG. 58/// 59/// Example usage: 60/// 61/// CFGBuilder builder; 62/// CFG* cfg = builder.BuildAST(stmt1); 63/// 64/// CFG construction is done via a recursive walk of an AST. We actually parse 65/// the AST in reverse order so that the successor of a basic block is 66/// constructed prior to its predecessor. This allows us to nicely capture 67/// implicit fall-throughs without extra basic blocks. 68/// 69class CFGBuilder { 70 ASTContext *Context; 71 llvm::OwningPtr<CFG> cfg; 72 73 CFGBlock* Block; 74 CFGBlock* Succ; 75 CFGBlock* ContinueTargetBlock; 76 CFGBlock* BreakTargetBlock; 77 CFGBlock* SwitchTerminatedBlock; 78 CFGBlock* DefaultCaseBlock; 79 CFGBlock* TryTerminatedBlock; 80 81 // LabelMap records the mapping from Label expressions to their blocks. 82 typedef llvm::DenseMap<LabelStmt*,CFGBlock*> LabelMapTy; 83 LabelMapTy LabelMap; 84 85 // A list of blocks that end with a "goto" that must be backpatched to their 86 // resolved targets upon completion of CFG construction. 87 typedef std::vector<CFGBlock*> BackpatchBlocksTy; 88 BackpatchBlocksTy BackpatchBlocks; 89 90 // A list of labels whose address has been taken (for indirect gotos). 91 typedef llvm::SmallPtrSet<LabelStmt*,5> LabelSetTy; 92 LabelSetTy AddressTakenLabels; 93 94public: 95 explicit CFGBuilder() : cfg(new CFG()), // crew a new CFG 96 Block(NULL), Succ(NULL), 97 ContinueTargetBlock(NULL), BreakTargetBlock(NULL), 98 SwitchTerminatedBlock(NULL), DefaultCaseBlock(NULL), 99 TryTerminatedBlock(NULL) {} 100 101 // buildCFG - Used by external clients to construct the CFG. 102 CFG* buildCFG(const Decl *D, Stmt *Statement, ASTContext *C, 103 bool pruneTriviallyFalseEdges, bool AddEHEdges, 104 bool AddScopes); 105 106private: 107 // Visitors to walk an AST and construct the CFG. 108 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc); 109 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc); 110 CFGBlock *VisitBlockExpr(BlockExpr* E, AddStmtChoice asc); 111 CFGBlock *VisitBreakStmt(BreakStmt *B); 112 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S); 113 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 114 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 115 CFGBlock *VisitCXXMemberCallExpr(CXXMemberCallExpr *C, AddStmtChoice asc); 116 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 117 CFGBlock *VisitCaseStmt(CaseStmt *C); 118 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 119 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 120 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, AddStmtChoice asc); 121 CFGBlock *VisitContinueStmt(ContinueStmt *C); 122 CFGBlock *VisitDeclStmt(DeclStmt *DS); 123 CFGBlock *VisitDeclSubExpr(Decl* D); 124 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 125 CFGBlock *VisitDoStmt(DoStmt *D); 126 CFGBlock *VisitForStmt(ForStmt *F); 127 CFGBlock *VisitGotoStmt(GotoStmt* G); 128 CFGBlock *VisitIfStmt(IfStmt *I); 129 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 130 CFGBlock *VisitLabelStmt(LabelStmt *L); 131 CFGBlock *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc); 132 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 133 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 134 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 135 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 136 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 137 CFGBlock *VisitReturnStmt(ReturnStmt* R); 138 CFGBlock *VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, AddStmtChoice asc); 139 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 140 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 141 CFGBlock *VisitWhileStmt(WhileStmt *W); 142 143 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 144 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 145 CFGBlock *VisitChildren(Stmt* S); 146 147 // NYS == Not Yet Supported 148 CFGBlock* NYS() { 149 badCFG = true; 150 return Block; 151 } 152 153 CFGBlock *StartScope(Stmt *S, CFGBlock *B) { 154 if (!AddScopes) 155 return B; 156 157 if (B == 0) 158 B = createBlock(); 159 B->StartScope(S, cfg->getBumpVectorContext()); 160 return B; 161 } 162 163 void EndScope(Stmt *S) { 164 if (!AddScopes) 165 return; 166 167 if (Block == 0) 168 Block = createBlock(); 169 Block->EndScope(S, cfg->getBumpVectorContext()); 170 } 171 172 void autoCreateBlock() { if (!Block) Block = createBlock(); } 173 CFGBlock *createBlock(bool add_successor = true); 174 bool FinishBlock(CFGBlock* B); 175 CFGBlock *addStmt(Stmt *S) { 176 return Visit(S, AddStmtChoice::AlwaysAdd); 177 } 178 179 void AppendStmt(CFGBlock *B, Stmt *S, 180 AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 181 B->appendStmt(S, cfg->getBumpVectorContext(), asc.asLValue()); 182 } 183 184 void AddSuccessor(CFGBlock *B, CFGBlock *S) { 185 B->addSuccessor(S, cfg->getBumpVectorContext()); 186 } 187 188 /// TryResult - a class representing a variant over the values 189 /// 'true', 'false', or 'unknown'. This is returned by TryEvaluateBool, 190 /// and is used by the CFGBuilder to decide if a branch condition 191 /// can be decided up front during CFG construction. 192 class TryResult { 193 int X; 194 public: 195 TryResult(bool b) : X(b ? 1 : 0) {} 196 TryResult() : X(-1) {} 197 198 bool isTrue() const { return X == 1; } 199 bool isFalse() const { return X == 0; } 200 bool isKnown() const { return X >= 0; } 201 void negate() { 202 assert(isKnown()); 203 X ^= 0x1; 204 } 205 }; 206 207 /// TryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 208 /// if we can evaluate to a known value, otherwise return -1. 209 TryResult TryEvaluateBool(Expr *S) { 210 if (!PruneTriviallyFalseEdges) 211 return TryResult(); 212 213 Expr::EvalResult Result; 214 if (!S->isTypeDependent() && !S->isValueDependent() && 215 S->Evaluate(Result, *Context) && Result.Val.isInt()) 216 return Result.Val.getInt().getBoolValue(); 217 218 return TryResult(); 219 } 220 221 bool badCFG; 222 223 // True iff trivially false edges should be pruned from the CFG. 224 bool PruneTriviallyFalseEdges; 225 226 // True iff EH edges on CallExprs should be added to the CFG. 227 bool AddEHEdges; 228 229 // True iff scope start and scope end notes should be added to the CFG. 230 bool AddScopes; 231}; 232 233// FIXME: Add support for dependent-sized array types in C++? 234// Does it even make sense to build a CFG for an uninstantiated template? 235static VariableArrayType* FindVA(Type* t) { 236 while (ArrayType* vt = dyn_cast<ArrayType>(t)) { 237 if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt)) 238 if (vat->getSizeExpr()) 239 return vat; 240 241 t = vt->getElementType().getTypePtr(); 242 } 243 244 return 0; 245} 246 247/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 248/// arbitrary statement. Examples include a single expression or a function 249/// body (compound statement). The ownership of the returned CFG is 250/// transferred to the caller. If CFG construction fails, this method returns 251/// NULL. 252CFG* CFGBuilder::buildCFG(const Decl *D, Stmt* Statement, ASTContext* C, 253 bool pruneTriviallyFalseEdges, 254 bool addehedges, bool AddScopes) { 255 256 AddEHEdges = addehedges; 257 PruneTriviallyFalseEdges = pruneTriviallyFalseEdges; 258 259 Context = C; 260 assert(cfg.get()); 261 if (!Statement) 262 return NULL; 263 264 this->AddScopes = AddScopes; 265 badCFG = false; 266 267 // Create an empty block that will serve as the exit block for the CFG. Since 268 // this is the first block added to the CFG, it will be implicitly registered 269 // as the exit block. 270 Succ = createBlock(); 271 assert(Succ == &cfg->getExit()); 272 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 273 274 // Visit the statements and create the CFG. 275 CFGBlock* B = addStmt(Statement); 276 277 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 278 // FIXME: Add code for base initializers and member initializers. 279 (void)CD; 280 } 281 if (!B) 282 B = Succ; 283 284 if (B) { 285 // Finalize the last constructed block. This usually involves reversing the 286 // order of the statements in the block. 287 if (Block) FinishBlock(B); 288 289 // Backpatch the gotos whose label -> block mappings we didn't know when we 290 // encountered them. 291 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 292 E = BackpatchBlocks.end(); I != E; ++I ) { 293 294 CFGBlock* B = *I; 295 GotoStmt* G = cast<GotoStmt>(B->getTerminator()); 296 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 297 298 // If there is no target for the goto, then we are looking at an 299 // incomplete AST. Handle this by not registering a successor. 300 if (LI == LabelMap.end()) continue; 301 302 AddSuccessor(B, LI->second); 303 } 304 305 // Add successors to the Indirect Goto Dispatch block (if we have one). 306 if (CFGBlock* B = cfg->getIndirectGotoBlock()) 307 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 308 E = AddressTakenLabels.end(); I != E; ++I ) { 309 310 // Lookup the target block. 311 LabelMapTy::iterator LI = LabelMap.find(*I); 312 313 // If there is no target block that contains label, then we are looking 314 // at an incomplete AST. Handle this by not registering a successor. 315 if (LI == LabelMap.end()) continue; 316 317 AddSuccessor(B, LI->second); 318 } 319 320 Succ = B; 321 } 322 323 // Create an empty entry block that has no predecessors. 324 cfg->setEntry(createBlock()); 325 326 return badCFG ? NULL : cfg.take(); 327} 328 329/// createBlock - Used to lazily create blocks that are connected 330/// to the current (global) succcessor. 331CFGBlock* CFGBuilder::createBlock(bool add_successor) { 332 CFGBlock* B = cfg->createBlock(); 333 if (add_successor && Succ) 334 AddSuccessor(B, Succ); 335 return B; 336} 337 338/// FinishBlock - "Finalize" the block by checking if we have a bad CFG. 339bool CFGBuilder::FinishBlock(CFGBlock* B) { 340 if (badCFG) 341 return false; 342 343 assert(B); 344 return true; 345} 346 347/// Visit - Walk the subtree of a statement and add extra 348/// blocks for ternary operators, &&, and ||. We also process "," and 349/// DeclStmts (which may contain nested control-flow). 350CFGBlock* CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 351tryAgain: 352 if (!S) { 353 badCFG = true; 354 return 0; 355 } 356 switch (S->getStmtClass()) { 357 default: 358 return VisitStmt(S, asc); 359 360 case Stmt::AddrLabelExprClass: 361 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 362 363 case Stmt::BinaryOperatorClass: 364 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 365 366 case Stmt::BlockExprClass: 367 return VisitBlockExpr(cast<BlockExpr>(S), asc); 368 369 case Stmt::BreakStmtClass: 370 return VisitBreakStmt(cast<BreakStmt>(S)); 371 372 case Stmt::CallExprClass: 373 return VisitCallExpr(cast<CallExpr>(S), asc); 374 375 case Stmt::CaseStmtClass: 376 return VisitCaseStmt(cast<CaseStmt>(S)); 377 378 case Stmt::ChooseExprClass: 379 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 380 381 case Stmt::CompoundStmtClass: 382 return VisitCompoundStmt(cast<CompoundStmt>(S)); 383 384 case Stmt::ConditionalOperatorClass: 385 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 386 387 case Stmt::ContinueStmtClass: 388 return VisitContinueStmt(cast<ContinueStmt>(S)); 389 390 case Stmt::CXXCatchStmtClass: 391 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 392 393 case Stmt::CXXMemberCallExprClass: 394 return VisitCXXMemberCallExpr(cast<CXXMemberCallExpr>(S), asc); 395 396 case Stmt::CXXThrowExprClass: 397 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 398 399 case Stmt::CXXTryStmtClass: 400 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 401 402 case Stmt::DeclStmtClass: 403 return VisitDeclStmt(cast<DeclStmt>(S)); 404 405 case Stmt::DefaultStmtClass: 406 return VisitDefaultStmt(cast<DefaultStmt>(S)); 407 408 case Stmt::DoStmtClass: 409 return VisitDoStmt(cast<DoStmt>(S)); 410 411 case Stmt::ForStmtClass: 412 return VisitForStmt(cast<ForStmt>(S)); 413 414 case Stmt::GotoStmtClass: 415 return VisitGotoStmt(cast<GotoStmt>(S)); 416 417 case Stmt::IfStmtClass: 418 return VisitIfStmt(cast<IfStmt>(S)); 419 420 case Stmt::IndirectGotoStmtClass: 421 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 422 423 case Stmt::LabelStmtClass: 424 return VisitLabelStmt(cast<LabelStmt>(S)); 425 426 case Stmt::MemberExprClass: 427 return VisitMemberExpr(cast<MemberExpr>(S), asc); 428 429 case Stmt::ObjCAtCatchStmtClass: 430 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 431 432 case Stmt::ObjCAtSynchronizedStmtClass: 433 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 434 435 case Stmt::ObjCAtThrowStmtClass: 436 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 437 438 case Stmt::ObjCAtTryStmtClass: 439 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 440 441 case Stmt::ObjCForCollectionStmtClass: 442 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 443 444 case Stmt::ParenExprClass: 445 S = cast<ParenExpr>(S)->getSubExpr(); 446 goto tryAgain; 447 448 case Stmt::NullStmtClass: 449 return Block; 450 451 case Stmt::ReturnStmtClass: 452 return VisitReturnStmt(cast<ReturnStmt>(S)); 453 454 case Stmt::SizeOfAlignOfExprClass: 455 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 456 457 case Stmt::StmtExprClass: 458 return VisitStmtExpr(cast<StmtExpr>(S), asc); 459 460 case Stmt::SwitchStmtClass: 461 return VisitSwitchStmt(cast<SwitchStmt>(S)); 462 463 case Stmt::WhileStmtClass: 464 return VisitWhileStmt(cast<WhileStmt>(S)); 465 } 466} 467 468CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 469 if (asc.alwaysAdd()) { 470 autoCreateBlock(); 471 AppendStmt(Block, S, asc); 472 } 473 474 return VisitChildren(S); 475} 476 477/// VisitChildren - Visit the children of a Stmt. 478CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 479 CFGBlock *B = Block; 480 for (Stmt::child_iterator I = Terminator->child_begin(), 481 E = Terminator->child_end(); I != E; ++I) { 482 if (*I) B = Visit(*I); 483 } 484 return B; 485} 486 487CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 488 AddStmtChoice asc) { 489 AddressTakenLabels.insert(A->getLabel()); 490 491 if (asc.alwaysAdd()) { 492 autoCreateBlock(); 493 AppendStmt(Block, A, asc); 494 } 495 496 return Block; 497} 498 499CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 500 AddStmtChoice asc) { 501 if (B->isLogicalOp()) { // && or || 502 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 503 AppendStmt(ConfluenceBlock, B, asc); 504 505 if (!FinishBlock(ConfluenceBlock)) 506 return 0; 507 508 // create the block evaluating the LHS 509 CFGBlock* LHSBlock = createBlock(false); 510 LHSBlock->setTerminator(B); 511 512 // create the block evaluating the RHS 513 Succ = ConfluenceBlock; 514 Block = NULL; 515 CFGBlock* RHSBlock = addStmt(B->getRHS()); 516 517 if (RHSBlock) { 518 if (!FinishBlock(RHSBlock)) 519 return 0; 520 } 521 else { 522 // Create an empty block for cases where the RHS doesn't require 523 // any explicit statements in the CFG. 524 RHSBlock = createBlock(); 525 } 526 527 // See if this is a known constant. 528 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 529 if (KnownVal.isKnown() && (B->getOpcode() == BinaryOperator::LOr)) 530 KnownVal.negate(); 531 532 // Now link the LHSBlock with RHSBlock. 533 if (B->getOpcode() == BinaryOperator::LOr) { 534 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 535 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 536 } else { 537 assert(B->getOpcode() == BinaryOperator::LAnd); 538 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 539 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 540 } 541 542 // Generate the blocks for evaluating the LHS. 543 Block = LHSBlock; 544 return addStmt(B->getLHS()); 545 } 546 else if (B->getOpcode() == BinaryOperator::Comma) { // , 547 autoCreateBlock(); 548 AppendStmt(Block, B, asc); 549 addStmt(B->getRHS()); 550 return addStmt(B->getLHS()); 551 } 552 else if (B->isAssignmentOp()) { 553 if (asc.alwaysAdd()) { 554 autoCreateBlock(); 555 AppendStmt(Block, B, asc); 556 } 557 558 Visit(B->getRHS()); 559 return Visit(B->getLHS(), AddStmtChoice::AsLValueNotAlwaysAdd); 560 } 561 562 return VisitStmt(B, asc); 563} 564 565CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 566 if (asc.alwaysAdd()) { 567 autoCreateBlock(); 568 AppendStmt(Block, E, asc); 569 } 570 return Block; 571} 572 573CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 574 // "break" is a control-flow statement. Thus we stop processing the current 575 // block. 576 if (Block && !FinishBlock(Block)) 577 return 0; 578 579 // Now create a new block that ends with the break statement. 580 Block = createBlock(false); 581 Block->setTerminator(B); 582 583 // If there is no target for the break, then we are looking at an incomplete 584 // AST. This means that the CFG cannot be constructed. 585 if (BreakTargetBlock) 586 AddSuccessor(Block, BreakTargetBlock); 587 else 588 badCFG = true; 589 590 591 return Block; 592} 593 594static bool CanThrow(Expr *E) { 595 QualType Ty = E->getType(); 596 if (Ty->isFunctionPointerType()) 597 Ty = Ty->getAs<PointerType>()->getPointeeType(); 598 else if (Ty->isBlockPointerType()) 599 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 600 601 const FunctionType *FT = Ty->getAs<FunctionType>(); 602 if (FT) { 603 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 604 if (Proto->hasEmptyExceptionSpec()) 605 return false; 606 } 607 return true; 608} 609 610CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 611 // If this is a call to a no-return function, this stops the block here. 612 bool NoReturn = false; 613 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 614 NoReturn = true; 615 } 616 617 bool AddEHEdge = false; 618 619 // Languages without exceptions are assumed to not throw. 620 if (Context->getLangOptions().Exceptions) { 621 if (AddEHEdges) 622 AddEHEdge = true; 623 } 624 625 if (FunctionDecl *FD = C->getDirectCallee()) { 626 if (FD->hasAttr<NoReturnAttr>()) 627 NoReturn = true; 628 if (FD->hasAttr<NoThrowAttr>()) 629 AddEHEdge = false; 630 } 631 632 if (!CanThrow(C->getCallee())) 633 AddEHEdge = false; 634 635 if (!NoReturn && !AddEHEdge) { 636 if (asc.asLValue()) 637 return VisitStmt(C, AddStmtChoice::AlwaysAddAsLValue); 638 else 639 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 640 } 641 642 if (Block) { 643 Succ = Block; 644 if (!FinishBlock(Block)) 645 return 0; 646 } 647 648 Block = createBlock(!NoReturn); 649 AppendStmt(Block, C, asc); 650 651 if (NoReturn) { 652 // Wire this to the exit block directly. 653 AddSuccessor(Block, &cfg->getExit()); 654 } 655 if (AddEHEdge) { 656 // Add exceptional edges. 657 if (TryTerminatedBlock) 658 AddSuccessor(Block, TryTerminatedBlock); 659 else 660 AddSuccessor(Block, &cfg->getExit()); 661 } 662 663 return VisitChildren(C); 664} 665 666CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 667 AddStmtChoice asc) { 668 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 669 AppendStmt(ConfluenceBlock, C, asc); 670 if (!FinishBlock(ConfluenceBlock)) 671 return 0; 672 673 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 674 : AddStmtChoice::AlwaysAdd; 675 676 Succ = ConfluenceBlock; 677 Block = NULL; 678 CFGBlock* LHSBlock = Visit(C->getLHS(), asc); 679 if (!FinishBlock(LHSBlock)) 680 return 0; 681 682 Succ = ConfluenceBlock; 683 Block = NULL; 684 CFGBlock* RHSBlock = Visit(C->getRHS(), asc); 685 if (!FinishBlock(RHSBlock)) 686 return 0; 687 688 Block = createBlock(false); 689 // See if this is a known constant. 690 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 691 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 692 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 693 Block->setTerminator(C); 694 return addStmt(C->getCond()); 695} 696 697 698CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 699 EndScope(C); 700 701 CFGBlock* LastBlock = Block; 702 703 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 704 I != E; ++I ) { 705 // If we hit a segment of code just containing ';' (NullStmts), we can 706 // get a null block back. In such cases, just use the LastBlock 707 if (CFGBlock *newBlock = addStmt(*I)) 708 LastBlock = newBlock; 709 710 if (badCFG) 711 return NULL; 712 } 713 714 LastBlock = StartScope(C, LastBlock); 715 716 return LastBlock; 717} 718 719CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 720 AddStmtChoice asc) { 721 // Create the confluence block that will "merge" the results of the ternary 722 // expression. 723 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 724 AppendStmt(ConfluenceBlock, C, asc); 725 if (!FinishBlock(ConfluenceBlock)) 726 return 0; 727 728 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 729 : AddStmtChoice::AlwaysAdd; 730 731 // Create a block for the LHS expression if there is an LHS expression. A 732 // GCC extension allows LHS to be NULL, causing the condition to be the 733 // value that is returned instead. 734 // e.g: x ?: y is shorthand for: x ? x : y; 735 Succ = ConfluenceBlock; 736 Block = NULL; 737 CFGBlock* LHSBlock = NULL; 738 if (C->getLHS()) { 739 LHSBlock = Visit(C->getLHS(), asc); 740 if (!FinishBlock(LHSBlock)) 741 return 0; 742 Block = NULL; 743 } 744 745 // Create the block for the RHS expression. 746 Succ = ConfluenceBlock; 747 CFGBlock* RHSBlock = Visit(C->getRHS(), asc); 748 if (!FinishBlock(RHSBlock)) 749 return 0; 750 751 // Create the block that will contain the condition. 752 Block = createBlock(false); 753 754 // See if this is a known constant. 755 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 756 if (LHSBlock) { 757 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 758 } else { 759 if (KnownVal.isFalse()) { 760 // If we know the condition is false, add NULL as the successor for 761 // the block containing the condition. In this case, the confluence 762 // block will have just one predecessor. 763 AddSuccessor(Block, 0); 764 assert(ConfluenceBlock->pred_size() == 1); 765 } else { 766 // If we have no LHS expression, add the ConfluenceBlock as a direct 767 // successor for the block containing the condition. Moreover, we need to 768 // reverse the order of the predecessors in the ConfluenceBlock because 769 // the RHSBlock will have been added to the succcessors already, and we 770 // want the first predecessor to the the block containing the expression 771 // for the case when the ternary expression evaluates to true. 772 AddSuccessor(Block, ConfluenceBlock); 773 assert(ConfluenceBlock->pred_size() == 2); 774 std::reverse(ConfluenceBlock->pred_begin(), 775 ConfluenceBlock->pred_end()); 776 } 777 } 778 779 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 780 Block->setTerminator(C); 781 return addStmt(C->getCond()); 782} 783 784CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 785 autoCreateBlock(); 786 787 if (DS->isSingleDecl()) { 788 AppendStmt(Block, DS); 789 return VisitDeclSubExpr(DS->getSingleDecl()); 790 } 791 792 CFGBlock *B = 0; 793 794 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 795 typedef llvm::SmallVector<Decl*,10> BufTy; 796 BufTy Buf(DS->decl_begin(), DS->decl_end()); 797 798 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 799 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 800 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 801 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 802 803 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 804 // automatically freed with the CFG. 805 DeclGroupRef DG(*I); 806 Decl *D = *I; 807 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 808 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 809 810 // Append the fake DeclStmt to block. 811 AppendStmt(Block, DSNew); 812 B = VisitDeclSubExpr(D); 813 } 814 815 return B; 816} 817 818/// VisitDeclSubExpr - Utility method to add block-level expressions for 819/// initializers in Decls. 820CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 821 assert(Block); 822 823 VarDecl *VD = dyn_cast<VarDecl>(D); 824 825 if (!VD) 826 return Block; 827 828 Expr *Init = VD->getInit(); 829 830 if (Init) { 831 AddStmtChoice::Kind k = 832 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 833 : AddStmtChoice::NotAlwaysAdd; 834 Visit(Init, AddStmtChoice(k)); 835 } 836 837 // If the type of VD is a VLA, then we must process its size expressions. 838 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 839 VA = FindVA(VA->getElementType().getTypePtr())) 840 Block = addStmt(VA->getSizeExpr()); 841 842 return Block; 843} 844 845CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 846 // We may see an if statement in the middle of a basic block, or it may be the 847 // first statement we are processing. In either case, we create a new basic 848 // block. First, we create the blocks for the then...else statements, and 849 // then we create the block containing the if statement. If we were in the 850 // middle of a block, we stop processing that block. That block is then the 851 // implicit successor for the "then" and "else" clauses. 852 853 // The block we were proccessing is now finished. Make it the successor 854 // block. 855 if (Block) { 856 Succ = Block; 857 if (!FinishBlock(Block)) 858 return 0; 859 } 860 861 // Process the false branch. 862 CFGBlock* ElseBlock = Succ; 863 864 if (Stmt* Else = I->getElse()) { 865 SaveAndRestore<CFGBlock*> sv(Succ); 866 867 // NULL out Block so that the recursive call to Visit will 868 // create a new basic block. 869 Block = NULL; 870 ElseBlock = addStmt(Else); 871 872 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 873 ElseBlock = sv.get(); 874 else if (Block) { 875 if (!FinishBlock(ElseBlock)) 876 return 0; 877 } 878 } 879 880 // Process the true branch. 881 CFGBlock* ThenBlock; 882 { 883 Stmt* Then = I->getThen(); 884 assert(Then); 885 SaveAndRestore<CFGBlock*> sv(Succ); 886 Block = NULL; 887 ThenBlock = addStmt(Then); 888 889 if (!ThenBlock) { 890 // We can reach here if the "then" body has all NullStmts. 891 // Create an empty block so we can distinguish between true and false 892 // branches in path-sensitive analyses. 893 ThenBlock = createBlock(false); 894 AddSuccessor(ThenBlock, sv.get()); 895 } else if (Block) { 896 if (!FinishBlock(ThenBlock)) 897 return 0; 898 } 899 } 900 901 // Now create a new block containing the if statement. 902 Block = createBlock(false); 903 904 // Set the terminator of the new block to the If statement. 905 Block->setTerminator(I); 906 907 // See if this is a known constant. 908 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 909 910 // Now add the successors. 911 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 912 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 913 914 // Add the condition as the last statement in the new block. This may create 915 // new blocks as the condition may contain control-flow. Any newly created 916 // blocks will be pointed to be "Block". 917 Block = addStmt(I->getCond()); 918 919 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 920 // and the condition variable initialization to the CFG. 921 if (VarDecl *VD = I->getConditionVariable()) { 922 if (Expr *Init = VD->getInit()) { 923 autoCreateBlock(); 924 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 925 addStmt(Init); 926 } 927 } 928 929 return Block; 930} 931 932 933CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 934 // If we were in the middle of a block we stop processing that block. 935 // 936 // NOTE: If a "return" appears in the middle of a block, this means that the 937 // code afterwards is DEAD (unreachable). We still keep a basic block 938 // for that code; a simple "mark-and-sweep" from the entry block will be 939 // able to report such dead blocks. 940 if (Block) 941 FinishBlock(Block); 942 943 // Create the new block. 944 Block = createBlock(false); 945 946 // The Exit block is the only successor. 947 AddSuccessor(Block, &cfg->getExit()); 948 949 // Add the return statement to the block. This may create new blocks if R 950 // contains control-flow (short-circuit operations). 951 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 952} 953 954CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 955 // Get the block of the labeled statement. Add it to our map. 956 addStmt(L->getSubStmt()); 957 CFGBlock* LabelBlock = Block; 958 959 if (!LabelBlock) // This can happen when the body is empty, i.e. 960 LabelBlock = createBlock(); // scopes that only contains NullStmts. 961 962 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 963 LabelMap[ L ] = LabelBlock; 964 965 // Labels partition blocks, so this is the end of the basic block we were 966 // processing (L is the block's label). Because this is label (and we have 967 // already processed the substatement) there is no extra control-flow to worry 968 // about. 969 LabelBlock->setLabel(L); 970 if (!FinishBlock(LabelBlock)) 971 return 0; 972 973 // We set Block to NULL to allow lazy creation of a new block (if necessary); 974 Block = NULL; 975 976 // This block is now the implicit successor of other blocks. 977 Succ = LabelBlock; 978 979 return LabelBlock; 980} 981 982CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 983 // Goto is a control-flow statement. Thus we stop processing the current 984 // block and create a new one. 985 if (Block) 986 FinishBlock(Block); 987 988 Block = createBlock(false); 989 Block->setTerminator(G); 990 991 // If we already know the mapping to the label block add the successor now. 992 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 993 994 if (I == LabelMap.end()) 995 // We will need to backpatch this block later. 996 BackpatchBlocks.push_back(Block); 997 else 998 AddSuccessor(Block, I->second); 999 1000 return Block; 1001} 1002 1003CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 1004 CFGBlock* LoopSuccessor = NULL; 1005 1006 // "for" is a control-flow statement. Thus we stop processing the current 1007 // block. 1008 if (Block) { 1009 if (!FinishBlock(Block)) 1010 return 0; 1011 LoopSuccessor = Block; 1012 } else 1013 LoopSuccessor = Succ; 1014 1015 // Save the current value for the break targets. 1016 // All breaks should go to the code following the loop. 1017 SaveAndRestore<CFGBlock*> save_break(BreakTargetBlock); 1018 BreakTargetBlock = LoopSuccessor; 1019 1020 // Because of short-circuit evaluation, the condition of the loop can span 1021 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1022 // evaluate the condition. 1023 CFGBlock* ExitConditionBlock = createBlock(false); 1024 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1025 1026 // Set the terminator for the "exit" condition block. 1027 ExitConditionBlock->setTerminator(F); 1028 1029 // Now add the actual condition to the condition block. Because the condition 1030 // itself may contain control-flow, new blocks may be created. 1031 if (Stmt* C = F->getCond()) { 1032 Block = ExitConditionBlock; 1033 EntryConditionBlock = addStmt(C); 1034 assert(Block == EntryConditionBlock); 1035 1036 // If this block contains a condition variable, add both the condition 1037 // variable and initializer to the CFG. 1038 if (VarDecl *VD = F->getConditionVariable()) { 1039 if (Expr *Init = VD->getInit()) { 1040 autoCreateBlock(); 1041 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 1042 EntryConditionBlock = addStmt(Init); 1043 assert(Block == EntryConditionBlock); 1044 } 1045 } 1046 1047 if (Block) { 1048 if (!FinishBlock(EntryConditionBlock)) 1049 return 0; 1050 } 1051 } 1052 1053 // The condition block is the implicit successor for the loop body as well as 1054 // any code above the loop. 1055 Succ = EntryConditionBlock; 1056 1057 // See if this is a known constant. 1058 TryResult KnownVal(true); 1059 1060 if (F->getCond()) 1061 KnownVal = TryEvaluateBool(F->getCond()); 1062 1063 // Now create the loop body. 1064 { 1065 assert(F->getBody()); 1066 1067 // Save the current values for Block, Succ, and continue targets. 1068 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1069 save_continue(ContinueTargetBlock); 1070 1071 // Create a new block to contain the (bottom) of the loop body. 1072 Block = NULL; 1073 1074 if (Stmt* I = F->getInc()) { 1075 // Generate increment code in its own basic block. This is the target of 1076 // continue statements. 1077 Succ = addStmt(I); 1078 } else { 1079 // No increment code. Create a special, empty, block that is used as the 1080 // target block for "looping back" to the start of the loop. 1081 assert(Succ == EntryConditionBlock); 1082 Succ = createBlock(); 1083 } 1084 1085 // Finish up the increment (or empty) block if it hasn't been already. 1086 if (Block) { 1087 assert(Block == Succ); 1088 if (!FinishBlock(Block)) 1089 return 0; 1090 Block = 0; 1091 } 1092 1093 ContinueTargetBlock = Succ; 1094 1095 // The starting block for the loop increment is the block that should 1096 // represent the 'loop target' for looping back to the start of the loop. 1097 ContinueTargetBlock->setLoopTarget(F); 1098 1099 // Now populate the body block, and in the process create new blocks as we 1100 // walk the body of the loop. 1101 CFGBlock* BodyBlock = addStmt(F->getBody()); 1102 1103 if (!BodyBlock) 1104 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1105 else if (Block && !FinishBlock(BodyBlock)) 1106 return 0; 1107 1108 // This new body block is a successor to our "exit" condition block. 1109 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1110 } 1111 1112 // Link up the condition block with the code that follows the loop. (the 1113 // false branch). 1114 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1115 1116 // If the loop contains initialization, create a new block for those 1117 // statements. This block can also contain statements that precede the loop. 1118 if (Stmt* I = F->getInit()) { 1119 Block = createBlock(); 1120 return addStmt(I); 1121 } else { 1122 // There is no loop initialization. We are thus basically a while loop. 1123 // NULL out Block to force lazy block construction. 1124 Block = NULL; 1125 Succ = EntryConditionBlock; 1126 return EntryConditionBlock; 1127 } 1128} 1129 1130CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) { 1131 if (asc.alwaysAdd()) { 1132 autoCreateBlock(); 1133 AppendStmt(Block, M, asc); 1134 } 1135 return Visit(M->getBase(), 1136 M->isArrow() ? AddStmtChoice::NotAlwaysAdd 1137 : AddStmtChoice::AsLValueNotAlwaysAdd); 1138} 1139 1140CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1141 // Objective-C fast enumeration 'for' statements: 1142 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1143 // 1144 // for ( Type newVariable in collection_expression ) { statements } 1145 // 1146 // becomes: 1147 // 1148 // prologue: 1149 // 1. collection_expression 1150 // T. jump to loop_entry 1151 // loop_entry: 1152 // 1. side-effects of element expression 1153 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1154 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1155 // TB: 1156 // statements 1157 // T. jump to loop_entry 1158 // FB: 1159 // what comes after 1160 // 1161 // and 1162 // 1163 // Type existingItem; 1164 // for ( existingItem in expression ) { statements } 1165 // 1166 // becomes: 1167 // 1168 // the same with newVariable replaced with existingItem; the binding works 1169 // the same except that for one ObjCForCollectionStmt::getElement() returns 1170 // a DeclStmt and the other returns a DeclRefExpr. 1171 // 1172 1173 CFGBlock* LoopSuccessor = 0; 1174 1175 if (Block) { 1176 if (!FinishBlock(Block)) 1177 return 0; 1178 LoopSuccessor = Block; 1179 Block = 0; 1180 } else 1181 LoopSuccessor = Succ; 1182 1183 // Build the condition blocks. 1184 CFGBlock* ExitConditionBlock = createBlock(false); 1185 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1186 1187 // Set the terminator for the "exit" condition block. 1188 ExitConditionBlock->setTerminator(S); 1189 1190 // The last statement in the block should be the ObjCForCollectionStmt, which 1191 // performs the actual binding to 'element' and determines if there are any 1192 // more items in the collection. 1193 AppendStmt(ExitConditionBlock, S); 1194 Block = ExitConditionBlock; 1195 1196 // Walk the 'element' expression to see if there are any side-effects. We 1197 // generate new blocks as necesary. We DON'T add the statement by default to 1198 // the CFG unless it contains control-flow. 1199 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1200 if (Block) { 1201 if (!FinishBlock(EntryConditionBlock)) 1202 return 0; 1203 Block = 0; 1204 } 1205 1206 // The condition block is the implicit successor for the loop body as well as 1207 // any code above the loop. 1208 Succ = EntryConditionBlock; 1209 1210 // Now create the true branch. 1211 { 1212 // Save the current values for Succ, continue and break targets. 1213 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1214 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1215 1216 BreakTargetBlock = LoopSuccessor; 1217 ContinueTargetBlock = EntryConditionBlock; 1218 1219 CFGBlock* BodyBlock = addStmt(S->getBody()); 1220 1221 if (!BodyBlock) 1222 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1223 else if (Block) { 1224 if (!FinishBlock(BodyBlock)) 1225 return 0; 1226 } 1227 1228 // This new body block is a successor to our "exit" condition block. 1229 AddSuccessor(ExitConditionBlock, BodyBlock); 1230 } 1231 1232 // Link up the condition block with the code that follows the loop. 1233 // (the false branch). 1234 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1235 1236 // Now create a prologue block to contain the collection expression. 1237 Block = createBlock(); 1238 return addStmt(S->getCollection()); 1239} 1240 1241CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1242 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1243 1244 // Inline the body. 1245 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1246 1247 // The sync body starts its own basic block. This makes it a little easier 1248 // for diagnostic clients. 1249 if (SyncBlock) { 1250 if (!FinishBlock(SyncBlock)) 1251 return 0; 1252 1253 Block = 0; 1254 Succ = SyncBlock; 1255 } 1256 1257 // Inline the sync expression. 1258 return addStmt(S->getSynchExpr()); 1259} 1260 1261CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1262 // FIXME 1263 return NYS(); 1264} 1265 1266CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1267 CFGBlock* LoopSuccessor = NULL; 1268 1269 // "while" is a control-flow statement. Thus we stop processing the current 1270 // block. 1271 if (Block) { 1272 if (!FinishBlock(Block)) 1273 return 0; 1274 LoopSuccessor = Block; 1275 } else 1276 LoopSuccessor = Succ; 1277 1278 // Because of short-circuit evaluation, the condition of the loop can span 1279 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1280 // evaluate the condition. 1281 CFGBlock* ExitConditionBlock = createBlock(false); 1282 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1283 1284 // Set the terminator for the "exit" condition block. 1285 ExitConditionBlock->setTerminator(W); 1286 1287 // Now add the actual condition to the condition block. Because the condition 1288 // itself may contain control-flow, new blocks may be created. Thus we update 1289 // "Succ" after adding the condition. 1290 if (Stmt* C = W->getCond()) { 1291 Block = ExitConditionBlock; 1292 EntryConditionBlock = addStmt(C); 1293 assert(Block == EntryConditionBlock); 1294 1295 // If this block contains a condition variable, add both the condition 1296 // variable and initializer to the CFG. 1297 if (VarDecl *VD = W->getConditionVariable()) { 1298 if (Expr *Init = VD->getInit()) { 1299 autoCreateBlock(); 1300 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1301 EntryConditionBlock = addStmt(Init); 1302 assert(Block == EntryConditionBlock); 1303 } 1304 } 1305 1306 if (Block) { 1307 if (!FinishBlock(EntryConditionBlock)) 1308 return 0; 1309 } 1310 } 1311 1312 // The condition block is the implicit successor for the loop body as well as 1313 // any code above the loop. 1314 Succ = EntryConditionBlock; 1315 1316 // See if this is a known constant. 1317 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1318 1319 // Process the loop body. 1320 { 1321 assert(W->getBody()); 1322 1323 // Save the current values for Block, Succ, and continue and break targets 1324 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1325 save_continue(ContinueTargetBlock), 1326 save_break(BreakTargetBlock); 1327 1328 // Create an empty block to represent the transition block for looping back 1329 // to the head of the loop. 1330 Block = 0; 1331 assert(Succ == EntryConditionBlock); 1332 Succ = createBlock(); 1333 Succ->setLoopTarget(W); 1334 ContinueTargetBlock = Succ; 1335 1336 // All breaks should go to the code following the loop. 1337 BreakTargetBlock = LoopSuccessor; 1338 1339 // NULL out Block to force lazy instantiation of blocks for the body. 1340 Block = NULL; 1341 1342 // Create the body. The returned block is the entry to the loop body. 1343 CFGBlock* BodyBlock = addStmt(W->getBody()); 1344 1345 if (!BodyBlock) 1346 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1347 else if (Block) { 1348 if (!FinishBlock(BodyBlock)) 1349 return 0; 1350 } 1351 1352 // Add the loop body entry as a successor to the condition. 1353 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1354 } 1355 1356 // Link up the condition block with the code that follows the loop. (the 1357 // false branch). 1358 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1359 1360 // There can be no more statements in the condition block since we loop back 1361 // to this block. NULL out Block to force lazy creation of another block. 1362 Block = NULL; 1363 1364 // Return the condition block, which is the dominating block for the loop. 1365 Succ = EntryConditionBlock; 1366 return EntryConditionBlock; 1367} 1368 1369 1370CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1371 // FIXME: For now we pretend that @catch and the code it contains does not 1372 // exit. 1373 return Block; 1374} 1375 1376CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1377 // FIXME: This isn't complete. We basically treat @throw like a return 1378 // statement. 1379 1380 // If we were in the middle of a block we stop processing that block. 1381 if (Block && !FinishBlock(Block)) 1382 return 0; 1383 1384 // Create the new block. 1385 Block = createBlock(false); 1386 1387 // The Exit block is the only successor. 1388 AddSuccessor(Block, &cfg->getExit()); 1389 1390 // Add the statement to the block. This may create new blocks if S contains 1391 // control-flow (short-circuit operations). 1392 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1393} 1394 1395CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1396 // If we were in the middle of a block we stop processing that block. 1397 if (Block && !FinishBlock(Block)) 1398 return 0; 1399 1400 // Create the new block. 1401 Block = createBlock(false); 1402 1403 if (TryTerminatedBlock) 1404 // The current try statement is the only successor. 1405 AddSuccessor(Block, TryTerminatedBlock); 1406 else 1407 // otherwise the Exit block is the only successor. 1408 AddSuccessor(Block, &cfg->getExit()); 1409 1410 // Add the statement to the block. This may create new blocks if S contains 1411 // control-flow (short-circuit operations). 1412 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1413} 1414 1415CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1416 CFGBlock* LoopSuccessor = NULL; 1417 1418 // "do...while" is a control-flow statement. Thus we stop processing the 1419 // current block. 1420 if (Block) { 1421 if (!FinishBlock(Block)) 1422 return 0; 1423 LoopSuccessor = Block; 1424 } else 1425 LoopSuccessor = Succ; 1426 1427 // Because of short-circuit evaluation, the condition of the loop can span 1428 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1429 // evaluate the condition. 1430 CFGBlock* ExitConditionBlock = createBlock(false); 1431 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1432 1433 // Set the terminator for the "exit" condition block. 1434 ExitConditionBlock->setTerminator(D); 1435 1436 // Now add the actual condition to the condition block. Because the condition 1437 // itself may contain control-flow, new blocks may be created. 1438 if (Stmt* C = D->getCond()) { 1439 Block = ExitConditionBlock; 1440 EntryConditionBlock = addStmt(C); 1441 if (Block) { 1442 if (!FinishBlock(EntryConditionBlock)) 1443 return 0; 1444 } 1445 } 1446 1447 // The condition block is the implicit successor for the loop body. 1448 Succ = EntryConditionBlock; 1449 1450 // See if this is a known constant. 1451 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1452 1453 // Process the loop body. 1454 CFGBlock* BodyBlock = NULL; 1455 { 1456 assert(D->getBody()); 1457 1458 // Save the current values for Block, Succ, and continue and break targets 1459 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1460 save_continue(ContinueTargetBlock), 1461 save_break(BreakTargetBlock); 1462 1463 // All continues within this loop should go to the condition block 1464 ContinueTargetBlock = EntryConditionBlock; 1465 1466 // All breaks should go to the code following the loop. 1467 BreakTargetBlock = LoopSuccessor; 1468 1469 // NULL out Block to force lazy instantiation of blocks for the body. 1470 Block = NULL; 1471 1472 // Create the body. The returned block is the entry to the loop body. 1473 BodyBlock = addStmt(D->getBody()); 1474 1475 if (!BodyBlock) 1476 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1477 else if (Block) { 1478 if (!FinishBlock(BodyBlock)) 1479 return 0; 1480 } 1481 1482 if (!KnownVal.isFalse()) { 1483 // Add an intermediate block between the BodyBlock and the 1484 // ExitConditionBlock to represent the "loop back" transition. Create an 1485 // empty block to represent the transition block for looping back to the 1486 // head of the loop. 1487 // FIXME: Can we do this more efficiently without adding another block? 1488 Block = NULL; 1489 Succ = BodyBlock; 1490 CFGBlock *LoopBackBlock = createBlock(); 1491 LoopBackBlock->setLoopTarget(D); 1492 1493 // Add the loop body entry as a successor to the condition. 1494 AddSuccessor(ExitConditionBlock, LoopBackBlock); 1495 } 1496 else 1497 AddSuccessor(ExitConditionBlock, NULL); 1498 } 1499 1500 // Link up the condition block with the code that follows the loop. 1501 // (the false branch). 1502 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1503 1504 // There can be no more statements in the body block(s) since we loop back to 1505 // the body. NULL out Block to force lazy creation of another block. 1506 Block = NULL; 1507 1508 // Return the loop body, which is the dominating block for the loop. 1509 Succ = BodyBlock; 1510 return BodyBlock; 1511} 1512 1513CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1514 // "continue" is a control-flow statement. Thus we stop processing the 1515 // current block. 1516 if (Block && !FinishBlock(Block)) 1517 return 0; 1518 1519 // Now create a new block that ends with the continue statement. 1520 Block = createBlock(false); 1521 Block->setTerminator(C); 1522 1523 // If there is no target for the continue, then we are looking at an 1524 // incomplete AST. This means the CFG cannot be constructed. 1525 if (ContinueTargetBlock) 1526 AddSuccessor(Block, ContinueTargetBlock); 1527 else 1528 badCFG = true; 1529 1530 return Block; 1531} 1532 1533CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1534 AddStmtChoice asc) { 1535 1536 if (asc.alwaysAdd()) { 1537 autoCreateBlock(); 1538 AppendStmt(Block, E); 1539 } 1540 1541 // VLA types have expressions that must be evaluated. 1542 if (E->isArgumentType()) { 1543 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1544 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1545 addStmt(VA->getSizeExpr()); 1546 } 1547 1548 return Block; 1549} 1550 1551/// VisitStmtExpr - Utility method to handle (nested) statement 1552/// expressions (a GCC extension). 1553CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1554 if (asc.alwaysAdd()) { 1555 autoCreateBlock(); 1556 AppendStmt(Block, SE); 1557 } 1558 return VisitCompoundStmt(SE->getSubStmt()); 1559} 1560 1561CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1562 // "switch" is a control-flow statement. Thus we stop processing the current 1563 // block. 1564 CFGBlock* SwitchSuccessor = NULL; 1565 1566 if (Block) { 1567 if (!FinishBlock(Block)) 1568 return 0; 1569 SwitchSuccessor = Block; 1570 } else SwitchSuccessor = Succ; 1571 1572 // Save the current "switch" context. 1573 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1574 save_break(BreakTargetBlock), 1575 save_default(DefaultCaseBlock); 1576 1577 // Set the "default" case to be the block after the switch statement. If the 1578 // switch statement contains a "default:", this value will be overwritten with 1579 // the block for that code. 1580 DefaultCaseBlock = SwitchSuccessor; 1581 1582 // Create a new block that will contain the switch statement. 1583 SwitchTerminatedBlock = createBlock(false); 1584 1585 // Now process the switch body. The code after the switch is the implicit 1586 // successor. 1587 Succ = SwitchSuccessor; 1588 BreakTargetBlock = SwitchSuccessor; 1589 1590 // When visiting the body, the case statements should automatically get linked 1591 // up to the switch. We also don't keep a pointer to the body, since all 1592 // control-flow from the switch goes to case/default statements. 1593 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1594 Block = NULL; 1595 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1596 if (Block) { 1597 if (!FinishBlock(BodyBlock)) 1598 return 0; 1599 } 1600 1601 // If we have no "default:" case, the default transition is to the code 1602 // following the switch body. 1603 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1604 1605 // Add the terminator and condition in the switch block. 1606 SwitchTerminatedBlock->setTerminator(Terminator); 1607 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1608 Block = SwitchTerminatedBlock; 1609 Block = addStmt(Terminator->getCond()); 1610 1611 // Finally, if the SwitchStmt contains a condition variable, add both the 1612 // SwitchStmt and the condition variable initialization to the CFG. 1613 if (VarDecl *VD = Terminator->getConditionVariable()) { 1614 if (Expr *Init = VD->getInit()) { 1615 autoCreateBlock(); 1616 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1617 addStmt(Init); 1618 } 1619 } 1620 1621 return Block; 1622} 1623 1624CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1625 // CaseStmts are essentially labels, so they are the first statement in a 1626 // block. 1627 CFGBlock *TopBlock = 0, *LastBlock = 0; 1628 1629 if (Stmt *Sub = CS->getSubStmt()) { 1630 // For deeply nested chains of CaseStmts, instead of doing a recursion 1631 // (which can blow out the stack), manually unroll and create blocks 1632 // along the way. 1633 while (isa<CaseStmt>(Sub)) { 1634 CFGBlock *CurrentBlock = createBlock(false); 1635 CurrentBlock->setLabel(CS); 1636 1637 if (TopBlock) 1638 AddSuccessor(LastBlock, CurrentBlock); 1639 else 1640 TopBlock = CurrentBlock; 1641 1642 AddSuccessor(SwitchTerminatedBlock, CurrentBlock); 1643 LastBlock = CurrentBlock; 1644 1645 CS = cast<CaseStmt>(Sub); 1646 Sub = CS->getSubStmt(); 1647 } 1648 1649 addStmt(Sub); 1650 } 1651 1652 CFGBlock* CaseBlock = Block; 1653 if (!CaseBlock) 1654 CaseBlock = createBlock(); 1655 1656 // Cases statements partition blocks, so this is the top of the basic block we 1657 // were processing (the "case XXX:" is the label). 1658 CaseBlock->setLabel(CS); 1659 1660 if (!FinishBlock(CaseBlock)) 1661 return 0; 1662 1663 // Add this block to the list of successors for the block with the switch 1664 // statement. 1665 assert(SwitchTerminatedBlock); 1666 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1667 1668 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1669 Block = NULL; 1670 1671 if (TopBlock) { 1672 AddSuccessor(LastBlock, CaseBlock); 1673 Succ = TopBlock; 1674 } 1675 else { 1676 // This block is now the implicit successor of other blocks. 1677 Succ = CaseBlock; 1678 } 1679 1680 return Succ; 1681} 1682 1683CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1684 if (Terminator->getSubStmt()) 1685 addStmt(Terminator->getSubStmt()); 1686 1687 DefaultCaseBlock = Block; 1688 1689 if (!DefaultCaseBlock) 1690 DefaultCaseBlock = createBlock(); 1691 1692 // Default statements partition blocks, so this is the top of the basic block 1693 // we were processing (the "default:" is the label). 1694 DefaultCaseBlock->setLabel(Terminator); 1695 1696 if (!FinishBlock(DefaultCaseBlock)) 1697 return 0; 1698 1699 // Unlike case statements, we don't add the default block to the successors 1700 // for the switch statement immediately. This is done when we finish 1701 // processing the switch statement. This allows for the default case 1702 // (including a fall-through to the code after the switch statement) to always 1703 // be the last successor of a switch-terminated block. 1704 1705 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1706 Block = NULL; 1707 1708 // This block is now the implicit successor of other blocks. 1709 Succ = DefaultCaseBlock; 1710 1711 return DefaultCaseBlock; 1712} 1713 1714CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1715 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1716 // current block. 1717 CFGBlock* TrySuccessor = NULL; 1718 1719 if (Block) { 1720 if (!FinishBlock(Block)) 1721 return 0; 1722 TrySuccessor = Block; 1723 } else TrySuccessor = Succ; 1724 1725 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1726 1727 // Create a new block that will contain the try statement. 1728 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1729 // Add the terminator in the try block. 1730 NewTryTerminatedBlock->setTerminator(Terminator); 1731 1732 bool HasCatchAll = false; 1733 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1734 // The code after the try is the implicit successor. 1735 Succ = TrySuccessor; 1736 CXXCatchStmt *CS = Terminator->getHandler(h); 1737 if (CS->getExceptionDecl() == 0) { 1738 HasCatchAll = true; 1739 } 1740 Block = NULL; 1741 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1742 if (CatchBlock == 0) 1743 return 0; 1744 // Add this block to the list of successors for the block with the try 1745 // statement. 1746 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1747 } 1748 if (!HasCatchAll) { 1749 if (PrevTryTerminatedBlock) 1750 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1751 else 1752 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1753 } 1754 1755 // The code after the try is the implicit successor. 1756 Succ = TrySuccessor; 1757 1758 // Save the current "try" context. 1759 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1760 TryTerminatedBlock = NewTryTerminatedBlock; 1761 1762 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1763 Block = NULL; 1764 Block = addStmt(Terminator->getTryBlock()); 1765 return Block; 1766} 1767 1768CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1769 // CXXCatchStmt are treated like labels, so they are the first statement in a 1770 // block. 1771 1772 if (CS->getHandlerBlock()) 1773 addStmt(CS->getHandlerBlock()); 1774 1775 CFGBlock* CatchBlock = Block; 1776 if (!CatchBlock) 1777 CatchBlock = createBlock(); 1778 1779 CatchBlock->setLabel(CS); 1780 1781 if (!FinishBlock(CatchBlock)) 1782 return 0; 1783 1784 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1785 Block = NULL; 1786 1787 return CatchBlock; 1788} 1789 1790CFGBlock *CFGBuilder::VisitCXXMemberCallExpr(CXXMemberCallExpr *C, 1791 AddStmtChoice asc) { 1792 AddStmtChoice::Kind K = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 1793 : AddStmtChoice::AlwaysAdd; 1794 autoCreateBlock(); 1795 AppendStmt(Block, C, AddStmtChoice(K)); 1796 return VisitChildren(C); 1797} 1798 1799CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1800 // Lazily create the indirect-goto dispatch block if there isn't one already. 1801 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1802 1803 if (!IBlock) { 1804 IBlock = createBlock(false); 1805 cfg->setIndirectGotoBlock(IBlock); 1806 } 1807 1808 // IndirectGoto is a control-flow statement. Thus we stop processing the 1809 // current block and create a new one. 1810 if (Block && !FinishBlock(Block)) 1811 return 0; 1812 1813 Block = createBlock(false); 1814 Block->setTerminator(I); 1815 AddSuccessor(Block, IBlock); 1816 return addStmt(I->getTarget()); 1817} 1818 1819} // end anonymous namespace 1820 1821/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1822/// no successors or predecessors. If this is the first block created in the 1823/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1824CFGBlock* CFG::createBlock() { 1825 bool first_block = begin() == end(); 1826 1827 // Create the block. 1828 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1829 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1830 Blocks.push_back(Mem, BlkBVC); 1831 1832 // If this is the first block, set it as the Entry and Exit. 1833 if (first_block) 1834 Entry = Exit = &back(); 1835 1836 // Return the block. 1837 return &back(); 1838} 1839 1840/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1841/// CFG is returned to the caller. 1842CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1843 bool PruneTriviallyFalse, 1844 bool AddEHEdges, bool AddScopes) { 1845 CFGBuilder Builder; 1846 return Builder.buildCFG(D, Statement, C, PruneTriviallyFalse, 1847 AddEHEdges, AddScopes); 1848} 1849 1850//===----------------------------------------------------------------------===// 1851// CFG: Queries for BlkExprs. 1852//===----------------------------------------------------------------------===// 1853 1854namespace { 1855 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1856} 1857 1858static void FindSubExprAssignments(Stmt *S, 1859 llvm::SmallPtrSet<Expr*,50>& Set) { 1860 if (!S) 1861 return; 1862 1863 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1864 Stmt *child = *I; 1865 if (!child) 1866 continue; 1867 1868 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1869 if (B->isAssignmentOp()) Set.insert(B); 1870 1871 FindSubExprAssignments(child, Set); 1872 } 1873} 1874 1875static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1876 BlkExprMapTy* M = new BlkExprMapTy(); 1877 1878 // Look for assignments that are used as subexpressions. These are the only 1879 // assignments that we want to *possibly* register as a block-level 1880 // expression. Basically, if an assignment occurs both in a subexpression and 1881 // at the block-level, it is a block-level expression. 1882 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1883 1884 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1885 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1886 FindSubExprAssignments(*BI, SubExprAssignments); 1887 1888 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1889 1890 // Iterate over the statements again on identify the Expr* and Stmt* at the 1891 // block-level that are block-level expressions. 1892 1893 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1894 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1895 1896 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1897 // Assignment expressions that are not nested within another 1898 // expression are really "statements" whose value is never used by 1899 // another expression. 1900 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1901 continue; 1902 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1903 // Special handling for statement expressions. The last statement in 1904 // the statement expression is also a block-level expr. 1905 const CompoundStmt* C = Terminator->getSubStmt(); 1906 if (!C->body_empty()) { 1907 unsigned x = M->size(); 1908 (*M)[C->body_back()] = x; 1909 } 1910 } 1911 1912 unsigned x = M->size(); 1913 (*M)[Exp] = x; 1914 } 1915 1916 // Look at terminators. The condition is a block-level expression. 1917 1918 Stmt* S = (*I)->getTerminatorCondition(); 1919 1920 if (S && M->find(S) == M->end()) { 1921 unsigned x = M->size(); 1922 (*M)[S] = x; 1923 } 1924 } 1925 1926 return M; 1927} 1928 1929CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1930 assert(S != NULL); 1931 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1932 1933 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1934 BlkExprMapTy::iterator I = M->find(S); 1935 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1936} 1937 1938unsigned CFG::getNumBlkExprs() { 1939 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1940 return M->size(); 1941 else { 1942 // We assume callers interested in the number of BlkExprs will want 1943 // the map constructed if it doesn't already exist. 1944 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1945 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1946 } 1947} 1948 1949//===----------------------------------------------------------------------===// 1950// Cleanup: CFG dstor. 1951//===----------------------------------------------------------------------===// 1952 1953CFG::~CFG() { 1954 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1955} 1956 1957//===----------------------------------------------------------------------===// 1958// CFG pretty printing 1959//===----------------------------------------------------------------------===// 1960 1961namespace { 1962 1963class StmtPrinterHelper : public PrinterHelper { 1964 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1965 StmtMapTy StmtMap; 1966 signed CurrentBlock; 1967 unsigned CurrentStmt; 1968 const LangOptions &LangOpts; 1969public: 1970 1971 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1972 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1973 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1974 unsigned j = 1; 1975 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1976 BI != BEnd; ++BI, ++j ) 1977 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1978 } 1979 } 1980 1981 virtual ~StmtPrinterHelper() {} 1982 1983 const LangOptions &getLangOpts() const { return LangOpts; } 1984 void setBlockID(signed i) { CurrentBlock = i; } 1985 void setStmtID(unsigned i) { CurrentStmt = i; } 1986 1987 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1988 1989 StmtMapTy::iterator I = StmtMap.find(Terminator); 1990 1991 if (I == StmtMap.end()) 1992 return false; 1993 1994 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 1995 && I->second.second == CurrentStmt) { 1996 return false; 1997 } 1998 1999 OS << "[B" << I->second.first << "." << I->second.second << "]"; 2000 return true; 2001 } 2002}; 2003} // end anonymous namespace 2004 2005 2006namespace { 2007class CFGBlockTerminatorPrint 2008 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 2009 2010 llvm::raw_ostream& OS; 2011 StmtPrinterHelper* Helper; 2012 PrintingPolicy Policy; 2013public: 2014 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 2015 const PrintingPolicy &Policy) 2016 : OS(os), Helper(helper), Policy(Policy) {} 2017 2018 void VisitIfStmt(IfStmt* I) { 2019 OS << "if "; 2020 I->getCond()->printPretty(OS,Helper,Policy); 2021 } 2022 2023 // Default case. 2024 void VisitStmt(Stmt* Terminator) { 2025 Terminator->printPretty(OS, Helper, Policy); 2026 } 2027 2028 void VisitForStmt(ForStmt* F) { 2029 OS << "for (" ; 2030 if (F->getInit()) 2031 OS << "..."; 2032 OS << "; "; 2033 if (Stmt* C = F->getCond()) 2034 C->printPretty(OS, Helper, Policy); 2035 OS << "; "; 2036 if (F->getInc()) 2037 OS << "..."; 2038 OS << ")"; 2039 } 2040 2041 void VisitWhileStmt(WhileStmt* W) { 2042 OS << "while " ; 2043 if (Stmt* C = W->getCond()) 2044 C->printPretty(OS, Helper, Policy); 2045 } 2046 2047 void VisitDoStmt(DoStmt* D) { 2048 OS << "do ... while "; 2049 if (Stmt* C = D->getCond()) 2050 C->printPretty(OS, Helper, Policy); 2051 } 2052 2053 void VisitSwitchStmt(SwitchStmt* Terminator) { 2054 OS << "switch "; 2055 Terminator->getCond()->printPretty(OS, Helper, Policy); 2056 } 2057 2058 void VisitCXXTryStmt(CXXTryStmt* CS) { 2059 OS << "try ..."; 2060 } 2061 2062 void VisitConditionalOperator(ConditionalOperator* C) { 2063 C->getCond()->printPretty(OS, Helper, Policy); 2064 OS << " ? ... : ..."; 2065 } 2066 2067 void VisitChooseExpr(ChooseExpr* C) { 2068 OS << "__builtin_choose_expr( "; 2069 C->getCond()->printPretty(OS, Helper, Policy); 2070 OS << " )"; 2071 } 2072 2073 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 2074 OS << "goto *"; 2075 I->getTarget()->printPretty(OS, Helper, Policy); 2076 } 2077 2078 void VisitBinaryOperator(BinaryOperator* B) { 2079 if (!B->isLogicalOp()) { 2080 VisitExpr(B); 2081 return; 2082 } 2083 2084 B->getLHS()->printPretty(OS, Helper, Policy); 2085 2086 switch (B->getOpcode()) { 2087 case BinaryOperator::LOr: 2088 OS << " || ..."; 2089 return; 2090 case BinaryOperator::LAnd: 2091 OS << " && ..."; 2092 return; 2093 default: 2094 assert(false && "Invalid logical operator."); 2095 } 2096 } 2097 2098 void VisitExpr(Expr* E) { 2099 E->printPretty(OS, Helper, Policy); 2100 } 2101}; 2102} // end anonymous namespace 2103 2104 2105static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2106 const CFGElement &E) { 2107 Stmt *Terminator = E; 2108 2109 if (E.asStartScope()) { 2110 OS << "start scope\n"; 2111 return; 2112 } 2113 if (E.asEndScope()) { 2114 OS << "end scope\n"; 2115 return; 2116 } 2117 2118 if (Helper) { 2119 // special printing for statement-expressions. 2120 if (StmtExpr* SE = dyn_cast<StmtExpr>(Terminator)) { 2121 CompoundStmt* Sub = SE->getSubStmt(); 2122 2123 if (Sub->child_begin() != Sub->child_end()) { 2124 OS << "({ ... ; "; 2125 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2126 OS << " })\n"; 2127 return; 2128 } 2129 } 2130 2131 // special printing for comma expressions. 2132 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Terminator)) { 2133 if (B->getOpcode() == BinaryOperator::Comma) { 2134 OS << "... , "; 2135 Helper->handledStmt(B->getRHS(),OS); 2136 OS << '\n'; 2137 return; 2138 } 2139 } 2140 } 2141 2142 Terminator->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2143 2144 // Expressions need a newline. 2145 if (isa<Expr>(Terminator)) OS << '\n'; 2146} 2147 2148static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2149 const CFGBlock& B, 2150 StmtPrinterHelper* Helper, bool print_edges) { 2151 2152 if (Helper) Helper->setBlockID(B.getBlockID()); 2153 2154 // Print the header. 2155 OS << "\n [ B" << B.getBlockID(); 2156 2157 if (&B == &cfg->getEntry()) 2158 OS << " (ENTRY) ]\n"; 2159 else if (&B == &cfg->getExit()) 2160 OS << " (EXIT) ]\n"; 2161 else if (&B == cfg->getIndirectGotoBlock()) 2162 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2163 else 2164 OS << " ]\n"; 2165 2166 // Print the label of this block. 2167 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2168 2169 if (print_edges) 2170 OS << " "; 2171 2172 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2173 OS << L->getName(); 2174 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2175 OS << "case "; 2176 C->getLHS()->printPretty(OS, Helper, 2177 PrintingPolicy(Helper->getLangOpts())); 2178 if (C->getRHS()) { 2179 OS << " ... "; 2180 C->getRHS()->printPretty(OS, Helper, 2181 PrintingPolicy(Helper->getLangOpts())); 2182 } 2183 } else if (isa<DefaultStmt>(Label)) 2184 OS << "default"; 2185 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2186 OS << "catch ("; 2187 if (CS->getExceptionDecl()) 2188 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2189 0); 2190 else 2191 OS << "..."; 2192 OS << ")"; 2193 2194 } else 2195 assert(false && "Invalid label statement in CFGBlock."); 2196 2197 OS << ":\n"; 2198 } 2199 2200 // Iterate through the statements in the block and print them. 2201 unsigned j = 1; 2202 2203 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2204 I != E ; ++I, ++j ) { 2205 2206 // Print the statement # in the basic block and the statement itself. 2207 if (print_edges) 2208 OS << " "; 2209 2210 OS << llvm::format("%3d", j) << ": "; 2211 2212 if (Helper) 2213 Helper->setStmtID(j); 2214 2215 print_stmt(OS,Helper,*I); 2216 } 2217 2218 // Print the terminator of this block. 2219 if (B.getTerminator()) { 2220 if (print_edges) 2221 OS << " "; 2222 2223 OS << " T: "; 2224 2225 if (Helper) Helper->setBlockID(-1); 2226 2227 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2228 PrintingPolicy(Helper->getLangOpts())); 2229 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2230 OS << '\n'; 2231 } 2232 2233 if (print_edges) { 2234 // Print the predecessors of this block. 2235 OS << " Predecessors (" << B.pred_size() << "):"; 2236 unsigned i = 0; 2237 2238 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2239 I != E; ++I, ++i) { 2240 2241 if (i == 8 || (i-8) == 0) 2242 OS << "\n "; 2243 2244 OS << " B" << (*I)->getBlockID(); 2245 } 2246 2247 OS << '\n'; 2248 2249 // Print the successors of this block. 2250 OS << " Successors (" << B.succ_size() << "):"; 2251 i = 0; 2252 2253 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2254 I != E; ++I, ++i) { 2255 2256 if (i == 8 || (i-8) % 10 == 0) 2257 OS << "\n "; 2258 2259 if (*I) 2260 OS << " B" << (*I)->getBlockID(); 2261 else 2262 OS << " NULL"; 2263 } 2264 2265 OS << '\n'; 2266 } 2267} 2268 2269 2270/// dump - A simple pretty printer of a CFG that outputs to stderr. 2271void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2272 2273/// print - A simple pretty printer of a CFG that outputs to an ostream. 2274void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2275 StmtPrinterHelper Helper(this, LO); 2276 2277 // Print the entry block. 2278 print_block(OS, this, getEntry(), &Helper, true); 2279 2280 // Iterate through the CFGBlocks and print them one by one. 2281 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2282 // Skip the entry block, because we already printed it. 2283 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2284 continue; 2285 2286 print_block(OS, this, **I, &Helper, true); 2287 } 2288 2289 // Print the exit block. 2290 print_block(OS, this, getExit(), &Helper, true); 2291 OS.flush(); 2292} 2293 2294/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2295void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2296 print(llvm::errs(), cfg, LO); 2297} 2298 2299/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2300/// Generally this will only be called from CFG::print. 2301void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2302 const LangOptions &LO) const { 2303 StmtPrinterHelper Helper(cfg, LO); 2304 print_block(OS, cfg, *this, &Helper, true); 2305} 2306 2307/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2308void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2309 const LangOptions &LO) const { 2310 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2311 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2312} 2313 2314Stmt* CFGBlock::getTerminatorCondition() { 2315 2316 if (!Terminator) 2317 return NULL; 2318 2319 Expr* E = NULL; 2320 2321 switch (Terminator->getStmtClass()) { 2322 default: 2323 break; 2324 2325 case Stmt::ForStmtClass: 2326 E = cast<ForStmt>(Terminator)->getCond(); 2327 break; 2328 2329 case Stmt::WhileStmtClass: 2330 E = cast<WhileStmt>(Terminator)->getCond(); 2331 break; 2332 2333 case Stmt::DoStmtClass: 2334 E = cast<DoStmt>(Terminator)->getCond(); 2335 break; 2336 2337 case Stmt::IfStmtClass: 2338 E = cast<IfStmt>(Terminator)->getCond(); 2339 break; 2340 2341 case Stmt::ChooseExprClass: 2342 E = cast<ChooseExpr>(Terminator)->getCond(); 2343 break; 2344 2345 case Stmt::IndirectGotoStmtClass: 2346 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2347 break; 2348 2349 case Stmt::SwitchStmtClass: 2350 E = cast<SwitchStmt>(Terminator)->getCond(); 2351 break; 2352 2353 case Stmt::ConditionalOperatorClass: 2354 E = cast<ConditionalOperator>(Terminator)->getCond(); 2355 break; 2356 2357 case Stmt::BinaryOperatorClass: // '&&' and '||' 2358 E = cast<BinaryOperator>(Terminator)->getLHS(); 2359 break; 2360 2361 case Stmt::ObjCForCollectionStmtClass: 2362 return Terminator; 2363 } 2364 2365 return E ? E->IgnoreParens() : NULL; 2366} 2367 2368bool CFGBlock::hasBinaryBranchTerminator() const { 2369 2370 if (!Terminator) 2371 return false; 2372 2373 Expr* E = NULL; 2374 2375 switch (Terminator->getStmtClass()) { 2376 default: 2377 return false; 2378 2379 case Stmt::ForStmtClass: 2380 case Stmt::WhileStmtClass: 2381 case Stmt::DoStmtClass: 2382 case Stmt::IfStmtClass: 2383 case Stmt::ChooseExprClass: 2384 case Stmt::ConditionalOperatorClass: 2385 case Stmt::BinaryOperatorClass: 2386 return true; 2387 } 2388 2389 return E ? E->IgnoreParens() : NULL; 2390} 2391 2392 2393//===----------------------------------------------------------------------===// 2394// CFG Graphviz Visualization 2395//===----------------------------------------------------------------------===// 2396 2397 2398#ifndef NDEBUG 2399static StmtPrinterHelper* GraphHelper; 2400#endif 2401 2402void CFG::viewCFG(const LangOptions &LO) const { 2403#ifndef NDEBUG 2404 StmtPrinterHelper H(this, LO); 2405 GraphHelper = &H; 2406 llvm::ViewGraph(this,"CFG"); 2407 GraphHelper = NULL; 2408#endif 2409} 2410 2411namespace llvm { 2412template<> 2413struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2414 2415 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2416 2417 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2418 2419#ifndef NDEBUG 2420 std::string OutSStr; 2421 llvm::raw_string_ostream Out(OutSStr); 2422 print_block(Out,Graph, *Node, GraphHelper, false); 2423 std::string& OutStr = Out.str(); 2424 2425 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2426 2427 // Process string output to make it nicer... 2428 for (unsigned i = 0; i != OutStr.length(); ++i) 2429 if (OutStr[i] == '\n') { // Left justify 2430 OutStr[i] = '\\'; 2431 OutStr.insert(OutStr.begin()+i+1, 'l'); 2432 } 2433 2434 return OutStr; 2435#else 2436 return ""; 2437#endif 2438 } 2439}; 2440} // end namespace llvm 2441