CFG.cpp revision 4c45aa1b00b91847acfb082acfaced3ffa294d1d
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, AlwaysAdd, AlwaysAddAsLValue }; 42public: 43 AddStmtChoice(Kind kind) : k(kind) {} 44 bool alwaysAdd() const { return k != NotAlwaysAdd; } 45 bool asLValue() const { return k == AlwaysAddAsLValue; } 46private: 47 Kind k; 48}; 49 50/// CFGBuilder - This class implements CFG construction from an AST. 51/// The builder is stateful: an instance of the builder should be used to only 52/// construct a single CFG. 53/// 54/// Example usage: 55/// 56/// CFGBuilder builder; 57/// CFG* cfg = builder.BuildAST(stmt1); 58/// 59/// CFG construction is done via a recursive walk of an AST. We actually parse 60/// the AST in reverse order so that the successor of a basic block is 61/// constructed prior to its predecessor. This allows us to nicely capture 62/// implicit fall-throughs without extra basic blocks. 63/// 64class CFGBuilder { 65 ASTContext *Context; 66 llvm::OwningPtr<CFG> cfg; 67 68 CFGBlock* Block; 69 CFGBlock* Succ; 70 CFGBlock* ContinueTargetBlock; 71 CFGBlock* BreakTargetBlock; 72 CFGBlock* SwitchTerminatedBlock; 73 CFGBlock* DefaultCaseBlock; 74 CFGBlock* TryTerminatedBlock; 75 76 // LabelMap records the mapping from Label expressions to their blocks. 77 typedef llvm::DenseMap<LabelStmt*,CFGBlock*> LabelMapTy; 78 LabelMapTy LabelMap; 79 80 // A list of blocks that end with a "goto" that must be backpatched to their 81 // resolved targets upon completion of CFG construction. 82 typedef std::vector<CFGBlock*> BackpatchBlocksTy; 83 BackpatchBlocksTy BackpatchBlocks; 84 85 // A list of labels whose address has been taken (for indirect gotos). 86 typedef llvm::SmallPtrSet<LabelStmt*,5> LabelSetTy; 87 LabelSetTy AddressTakenLabels; 88 89public: 90 explicit CFGBuilder() : cfg(new CFG()), // crew a new CFG 91 Block(NULL), Succ(NULL), 92 ContinueTargetBlock(NULL), BreakTargetBlock(NULL), 93 SwitchTerminatedBlock(NULL), DefaultCaseBlock(NULL), 94 TryTerminatedBlock(NULL) {} 95 96 // buildCFG - Used by external clients to construct the CFG. 97 CFG* buildCFG(const Decl *D, Stmt *Statement, ASTContext *C, bool AddEHEdges, 98 bool AddScopes); 99 100private: 101 // Visitors to walk an AST and construct the CFG. 102 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc); 103 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc); 104 CFGBlock *VisitBlockExpr(BlockExpr* E, AddStmtChoice asc); 105 CFGBlock *VisitBreakStmt(BreakStmt *B); 106 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 107 CFGBlock *VisitCaseStmt(CaseStmt *C); 108 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 109 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 110 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, 111 AddStmtChoice asc); 112 CFGBlock *VisitContinueStmt(ContinueStmt *C); 113 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S); 114 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 115 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 116 CFGBlock *VisitDeclStmt(DeclStmt *DS); 117 CFGBlock *VisitDeclSubExpr(Decl* D); 118 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 119 CFGBlock *VisitDoStmt(DoStmt *D); 120 CFGBlock *VisitForStmt(ForStmt *F); 121 CFGBlock *VisitGotoStmt(GotoStmt* G); 122 CFGBlock *VisitIfStmt(IfStmt *I); 123 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 124 CFGBlock *VisitLabelStmt(LabelStmt *L); 125 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 126 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 127 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 128 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 129 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 130 CFGBlock *VisitReturnStmt(ReturnStmt* R); 131 CFGBlock *VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, AddStmtChoice asc); 132 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 133 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 134 CFGBlock *VisitWhileStmt(WhileStmt *W); 135 136 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 137 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 138 CFGBlock *VisitChildren(Stmt* S); 139 140 // NYS == Not Yet Supported 141 CFGBlock* NYS() { 142 badCFG = true; 143 return Block; 144 } 145 146 CFGBlock *StartScope(Stmt *S, CFGBlock *B) { 147 if (!AddScopes) 148 return B; 149 150 if (B == 0) 151 B = createBlock(); 152 B->StartScope(S, cfg->getBumpVectorContext()); 153 return B; 154 } 155 156 void EndScope(Stmt *S) { 157 if (!AddScopes) 158 return; 159 160 if (Block == 0) 161 Block = createBlock(); 162 Block->EndScope(S, cfg->getBumpVectorContext()); 163 } 164 165 void autoCreateBlock() { if (!Block) Block = createBlock(); } 166 CFGBlock *createBlock(bool add_successor = true); 167 bool FinishBlock(CFGBlock* B); 168 CFGBlock *addStmt(Stmt *S, AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 169 return Visit(S, asc); 170 } 171 172 void AppendStmt(CFGBlock *B, Stmt *S, 173 AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 174 B->appendStmt(S, cfg->getBumpVectorContext(), asc.asLValue()); 175 } 176 177 void AddSuccessor(CFGBlock *B, CFGBlock *S) { 178 B->addSuccessor(S, cfg->getBumpVectorContext()); 179 } 180 181 /// TryResult - a class representing a variant over the values 182 /// 'true', 'false', or 'unknown'. This is returned by TryEvaluateBool, 183 /// and is used by the CFGBuilder to decide if a branch condition 184 /// can be decided up front during CFG construction. 185 class TryResult { 186 int X; 187 public: 188 TryResult(bool b) : X(b ? 1 : 0) {} 189 TryResult() : X(-1) {} 190 191 bool isTrue() const { return X == 1; } 192 bool isFalse() const { return X == 0; } 193 bool isKnown() const { return X >= 0; } 194 void negate() { 195 assert(isKnown()); 196 X ^= 0x1; 197 } 198 }; 199 200 /// TryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 201 /// if we can evaluate to a known value, otherwise return -1. 202 TryResult TryEvaluateBool(Expr *S) { 203 Expr::EvalResult Result; 204 if (!S->isTypeDependent() && !S->isValueDependent() && 205 S->Evaluate(Result, *Context) && Result.Val.isInt()) 206 return Result.Val.getInt().getBoolValue(); 207 208 return TryResult(); 209 } 210 211 bool badCFG; 212 213 // True iff EH edges on CallExprs should be added to the CFG. 214 bool AddEHEdges; 215 216 // True iff scope start and scope end notes should be added to the CFG. 217 bool AddScopes; 218}; 219 220// FIXME: Add support for dependent-sized array types in C++? 221// Does it even make sense to build a CFG for an uninstantiated template? 222static VariableArrayType* FindVA(Type* t) { 223 while (ArrayType* vt = dyn_cast<ArrayType>(t)) { 224 if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt)) 225 if (vat->getSizeExpr()) 226 return vat; 227 228 t = vt->getElementType().getTypePtr(); 229 } 230 231 return 0; 232} 233 234/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 235/// arbitrary statement. Examples include a single expression or a function 236/// body (compound statement). The ownership of the returned CFG is 237/// transferred to the caller. If CFG construction fails, this method returns 238/// NULL. 239CFG* CFGBuilder::buildCFG(const Decl *D, Stmt* Statement, ASTContext* C, 240 bool AddEHEdges, bool AddScopes) { 241 Context = C; 242 assert(cfg.get()); 243 if (!Statement) 244 return NULL; 245 246 this->AddScopes = AddScopes; 247 badCFG = false; 248 249 // Create an empty block that will serve as the exit block for the CFG. Since 250 // this is the first block added to the CFG, it will be implicitly registered 251 // as the exit block. 252 Succ = createBlock(); 253 assert(Succ == &cfg->getExit()); 254 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 255 256 // Visit the statements and create the CFG. 257 CFGBlock* B = addStmt(Statement); 258 259 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 260 // FIXME: Add code for base initializers and member initializers. 261 (void)CD; 262 } 263 if (!B) 264 B = Succ; 265 266 if (B) { 267 // Finalize the last constructed block. This usually involves reversing the 268 // order of the statements in the block. 269 if (Block) FinishBlock(B); 270 271 // Backpatch the gotos whose label -> block mappings we didn't know when we 272 // encountered them. 273 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 274 E = BackpatchBlocks.end(); I != E; ++I ) { 275 276 CFGBlock* B = *I; 277 GotoStmt* G = cast<GotoStmt>(B->getTerminator()); 278 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 279 280 // If there is no target for the goto, then we are looking at an 281 // incomplete AST. Handle this by not registering a successor. 282 if (LI == LabelMap.end()) continue; 283 284 AddSuccessor(B, LI->second); 285 } 286 287 // Add successors to the Indirect Goto Dispatch block (if we have one). 288 if (CFGBlock* B = cfg->getIndirectGotoBlock()) 289 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 290 E = AddressTakenLabels.end(); I != E; ++I ) { 291 292 // Lookup the target block. 293 LabelMapTy::iterator LI = LabelMap.find(*I); 294 295 // If there is no target block that contains label, then we are looking 296 // at an incomplete AST. Handle this by not registering a successor. 297 if (LI == LabelMap.end()) continue; 298 299 AddSuccessor(B, LI->second); 300 } 301 302 Succ = B; 303 } 304 305 // Create an empty entry block that has no predecessors. 306 cfg->setEntry(createBlock()); 307 308 return badCFG ? NULL : cfg.take(); 309} 310 311/// createBlock - Used to lazily create blocks that are connected 312/// to the current (global) succcessor. 313CFGBlock* CFGBuilder::createBlock(bool add_successor) { 314 CFGBlock* B = cfg->createBlock(); 315 if (add_successor && Succ) 316 AddSuccessor(B, Succ); 317 return B; 318} 319 320/// FinishBlock - "Finalize" the block by checking if we have a bad CFG. 321bool CFGBuilder::FinishBlock(CFGBlock* B) { 322 if (badCFG) 323 return false; 324 325 assert(B); 326 return true; 327} 328 329/// Visit - Walk the subtree of a statement and add extra 330/// blocks for ternary operators, &&, and ||. We also process "," and 331/// DeclStmts (which may contain nested control-flow). 332CFGBlock* CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 333tryAgain: 334 switch (S->getStmtClass()) { 335 default: 336 return VisitStmt(S, asc); 337 338 case Stmt::AddrLabelExprClass: 339 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 340 341 case Stmt::BinaryOperatorClass: 342 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 343 344 case Stmt::BlockExprClass: 345 return VisitBlockExpr(cast<BlockExpr>(S), asc); 346 347 case Stmt::BreakStmtClass: 348 return VisitBreakStmt(cast<BreakStmt>(S)); 349 350 case Stmt::CallExprClass: 351 return VisitCallExpr(cast<CallExpr>(S), asc); 352 353 case Stmt::CaseStmtClass: 354 return VisitCaseStmt(cast<CaseStmt>(S)); 355 356 case Stmt::ChooseExprClass: 357 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 358 359 case Stmt::CompoundStmtClass: 360 return VisitCompoundStmt(cast<CompoundStmt>(S)); 361 362 case Stmt::ConditionalOperatorClass: 363 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 364 365 case Stmt::ContinueStmtClass: 366 return VisitContinueStmt(cast<ContinueStmt>(S)); 367 368 case Stmt::CXXCatchStmtClass: 369 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 370 371 case Stmt::CXXThrowExprClass: 372 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 373 374 case Stmt::CXXTryStmtClass: 375 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 376 377 case Stmt::DeclStmtClass: 378 return VisitDeclStmt(cast<DeclStmt>(S)); 379 380 case Stmt::DefaultStmtClass: 381 return VisitDefaultStmt(cast<DefaultStmt>(S)); 382 383 case Stmt::DoStmtClass: 384 return VisitDoStmt(cast<DoStmt>(S)); 385 386 case Stmt::ForStmtClass: 387 return VisitForStmt(cast<ForStmt>(S)); 388 389 case Stmt::GotoStmtClass: 390 return VisitGotoStmt(cast<GotoStmt>(S)); 391 392 case Stmt::IfStmtClass: 393 return VisitIfStmt(cast<IfStmt>(S)); 394 395 case Stmt::IndirectGotoStmtClass: 396 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 397 398 case Stmt::LabelStmtClass: 399 return VisitLabelStmt(cast<LabelStmt>(S)); 400 401 case Stmt::ObjCAtCatchStmtClass: 402 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 403 404 case Stmt::ObjCAtSynchronizedStmtClass: 405 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 406 407 case Stmt::ObjCAtThrowStmtClass: 408 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 409 410 case Stmt::ObjCAtTryStmtClass: 411 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 412 413 case Stmt::ObjCForCollectionStmtClass: 414 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 415 416 case Stmt::ParenExprClass: 417 S = cast<ParenExpr>(S)->getSubExpr(); 418 goto tryAgain; 419 420 case Stmt::NullStmtClass: 421 return Block; 422 423 case Stmt::ReturnStmtClass: 424 return VisitReturnStmt(cast<ReturnStmt>(S)); 425 426 case Stmt::SizeOfAlignOfExprClass: 427 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 428 429 case Stmt::StmtExprClass: 430 return VisitStmtExpr(cast<StmtExpr>(S), asc); 431 432 case Stmt::SwitchStmtClass: 433 return VisitSwitchStmt(cast<SwitchStmt>(S)); 434 435 case Stmt::WhileStmtClass: 436 return VisitWhileStmt(cast<WhileStmt>(S)); 437 } 438} 439 440CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 441 if (asc.alwaysAdd()) { 442 autoCreateBlock(); 443 AppendStmt(Block, S, asc); 444 } 445 446 return VisitChildren(S); 447} 448 449/// VisitChildren - Visit the children of a Stmt. 450CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 451 CFGBlock *B = Block; 452 for (Stmt::child_iterator I = Terminator->child_begin(), 453 E = Terminator->child_end(); I != E; ++I) { 454 if (*I) B = Visit(*I); 455 } 456 return B; 457} 458 459CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 460 AddStmtChoice asc) { 461 AddressTakenLabels.insert(A->getLabel()); 462 463 if (asc.alwaysAdd()) { 464 autoCreateBlock(); 465 AppendStmt(Block, A, asc); 466 } 467 468 return Block; 469} 470 471CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 472 AddStmtChoice asc) { 473 if (B->isLogicalOp()) { // && or || 474 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 475 AppendStmt(ConfluenceBlock, B, asc); 476 477 if (!FinishBlock(ConfluenceBlock)) 478 return 0; 479 480 // create the block evaluating the LHS 481 CFGBlock* LHSBlock = createBlock(false); 482 LHSBlock->setTerminator(B); 483 484 // create the block evaluating the RHS 485 Succ = ConfluenceBlock; 486 Block = NULL; 487 CFGBlock* RHSBlock = addStmt(B->getRHS()); 488 if (!FinishBlock(RHSBlock)) 489 return 0; 490 491 // See if this is a known constant. 492 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 493 if (KnownVal.isKnown() && (B->getOpcode() == BinaryOperator::LOr)) 494 KnownVal.negate(); 495 496 // Now link the LHSBlock with RHSBlock. 497 if (B->getOpcode() == BinaryOperator::LOr) { 498 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 499 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 500 } else { 501 assert(B->getOpcode() == BinaryOperator::LAnd); 502 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 503 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 504 } 505 506 // Generate the blocks for evaluating the LHS. 507 Block = LHSBlock; 508 return addStmt(B->getLHS()); 509 } 510 else if (B->getOpcode() == BinaryOperator::Comma) { // , 511 autoCreateBlock(); 512 AppendStmt(Block, B, asc); 513 addStmt(B->getRHS()); 514 return addStmt(B->getLHS()); 515 } 516 517 return VisitStmt(B, asc); 518} 519 520CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 521 if (asc.alwaysAdd()) { 522 autoCreateBlock(); 523 AppendStmt(Block, E, asc); 524 } 525 return Block; 526} 527 528CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 529 // "break" is a control-flow statement. Thus we stop processing the current 530 // block. 531 if (Block && !FinishBlock(Block)) 532 return 0; 533 534 // Now create a new block that ends with the break statement. 535 Block = createBlock(false); 536 Block->setTerminator(B); 537 538 // If there is no target for the break, then we are looking at an incomplete 539 // AST. This means that the CFG cannot be constructed. 540 if (BreakTargetBlock) 541 AddSuccessor(Block, BreakTargetBlock); 542 else 543 badCFG = true; 544 545 546 return Block; 547} 548 549static bool CanThrow(Expr *E) { 550 QualType Ty = E->getType(); 551 if (Ty->isFunctionPointerType()) 552 Ty = Ty->getAs<PointerType>()->getPointeeType(); 553 else if (Ty->isBlockPointerType()) 554 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 555 556 const FunctionType *FT = Ty->getAs<FunctionType>(); 557 if (FT) { 558 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 559 if (Proto->hasEmptyExceptionSpec()) 560 return false; 561 } 562 return true; 563} 564 565CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 566 // If this is a call to a no-return function, this stops the block here. 567 bool NoReturn = false; 568 if (C->getCallee()->getType().getNoReturnAttr()) { 569 NoReturn = true; 570 } 571 572 bool AddEHEdge = false; 573 574 // Languages without exceptions are assumed to not throw. 575 if (Context->getLangOptions().Exceptions) { 576 if (AddEHEdges) 577 AddEHEdge = true; 578 } 579 580 if (FunctionDecl *FD = C->getDirectCallee()) { 581 if (FD->hasAttr<NoReturnAttr>()) 582 NoReturn = true; 583 if (FD->hasAttr<NoThrowAttr>()) 584 AddEHEdge = false; 585 } 586 587 if (!CanThrow(C->getCallee())) 588 AddEHEdge = false; 589 590 if (!NoReturn && !AddEHEdge) 591 return VisitStmt(C, asc); 592 593 if (Block) { 594 Succ = Block; 595 if (!FinishBlock(Block)) 596 return 0; 597 } 598 599 Block = createBlock(!NoReturn); 600 AppendStmt(Block, C, asc); 601 602 if (NoReturn) { 603 // Wire this to the exit block directly. 604 AddSuccessor(Block, &cfg->getExit()); 605 } 606 if (AddEHEdge) { 607 // Add exceptional edges. 608 if (TryTerminatedBlock) 609 AddSuccessor(Block, TryTerminatedBlock); 610 else 611 AddSuccessor(Block, &cfg->getExit()); 612 } 613 614 return VisitChildren(C); 615} 616 617CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 618 AddStmtChoice asc) { 619 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 620 AppendStmt(ConfluenceBlock, C, asc); 621 if (!FinishBlock(ConfluenceBlock)) 622 return 0; 623 624 Succ = ConfluenceBlock; 625 Block = NULL; 626 CFGBlock* LHSBlock = addStmt(C->getLHS()); 627 if (!FinishBlock(LHSBlock)) 628 return 0; 629 630 Succ = ConfluenceBlock; 631 Block = NULL; 632 CFGBlock* RHSBlock = addStmt(C->getRHS()); 633 if (!FinishBlock(RHSBlock)) 634 return 0; 635 636 Block = createBlock(false); 637 // See if this is a known constant. 638 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 639 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 640 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 641 Block->setTerminator(C); 642 return addStmt(C->getCond()); 643} 644 645 646CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 647 EndScope(C); 648 649 CFGBlock* LastBlock = Block; 650 651 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 652 I != E; ++I ) { 653 LastBlock = addStmt(*I); 654 655 if (badCFG) 656 return NULL; 657 } 658 659 LastBlock = StartScope(C, LastBlock); 660 661 return LastBlock; 662} 663 664CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 665 AddStmtChoice asc) { 666 // Create the confluence block that will "merge" the results of the ternary 667 // expression. 668 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 669 AppendStmt(ConfluenceBlock, C, asc); 670 if (!FinishBlock(ConfluenceBlock)) 671 return 0; 672 673 // Create a block for the LHS expression if there is an LHS expression. A 674 // GCC extension allows LHS to be NULL, causing the condition to be the 675 // value that is returned instead. 676 // e.g: x ?: y is shorthand for: x ? x : y; 677 Succ = ConfluenceBlock; 678 Block = NULL; 679 CFGBlock* LHSBlock = NULL; 680 if (C->getLHS()) { 681 LHSBlock = addStmt(C->getLHS()); 682 if (!FinishBlock(LHSBlock)) 683 return 0; 684 Block = NULL; 685 } 686 687 // Create the block for the RHS expression. 688 Succ = ConfluenceBlock; 689 CFGBlock* RHSBlock = addStmt(C->getRHS()); 690 if (!FinishBlock(RHSBlock)) 691 return 0; 692 693 // Create the block that will contain the condition. 694 Block = createBlock(false); 695 696 // See if this is a known constant. 697 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 698 if (LHSBlock) { 699 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 700 } else { 701 if (KnownVal.isFalse()) { 702 // If we know the condition is false, add NULL as the successor for 703 // the block containing the condition. In this case, the confluence 704 // block will have just one predecessor. 705 AddSuccessor(Block, 0); 706 assert(ConfluenceBlock->pred_size() == 1); 707 } else { 708 // If we have no LHS expression, add the ConfluenceBlock as a direct 709 // successor for the block containing the condition. Moreover, we need to 710 // reverse the order of the predecessors in the ConfluenceBlock because 711 // the RHSBlock will have been added to the succcessors already, and we 712 // want the first predecessor to the the block containing the expression 713 // for the case when the ternary expression evaluates to true. 714 AddSuccessor(Block, ConfluenceBlock); 715 assert(ConfluenceBlock->pred_size() == 2); 716 std::reverse(ConfluenceBlock->pred_begin(), 717 ConfluenceBlock->pred_end()); 718 } 719 } 720 721 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 722 Block->setTerminator(C); 723 return addStmt(C->getCond()); 724} 725 726CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 727 autoCreateBlock(); 728 729 if (DS->isSingleDecl()) { 730 AppendStmt(Block, DS); 731 return VisitDeclSubExpr(DS->getSingleDecl()); 732 } 733 734 CFGBlock *B = 0; 735 736 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 737 typedef llvm::SmallVector<Decl*,10> BufTy; 738 BufTy Buf(DS->decl_begin(), DS->decl_end()); 739 740 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 741 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 742 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 743 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 744 745 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 746 // automatically freed with the CFG. 747 DeclGroupRef DG(*I); 748 Decl *D = *I; 749 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 750 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 751 752 // Append the fake DeclStmt to block. 753 AppendStmt(Block, DSNew); 754 B = VisitDeclSubExpr(D); 755 } 756 757 return B; 758} 759 760/// VisitDeclSubExpr - Utility method to add block-level expressions for 761/// initializers in Decls. 762CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 763 assert(Block); 764 765 VarDecl *VD = dyn_cast<VarDecl>(D); 766 767 if (!VD) 768 return Block; 769 770 Expr *Init = VD->getInit(); 771 772 if (Init) { 773 // Optimization: Don't create separate block-level statements for literals. 774 switch (Init->getStmtClass()) { 775 case Stmt::IntegerLiteralClass: 776 case Stmt::CharacterLiteralClass: 777 case Stmt::StringLiteralClass: 778 break; 779 default: 780 Block = addStmt(Init, 781 VD->getType()->isReferenceType() 782 ? AddStmtChoice::AlwaysAddAsLValue 783 : AddStmtChoice::AlwaysAdd); 784 } 785 } 786 787 // If the type of VD is a VLA, then we must process its size expressions. 788 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 789 VA = FindVA(VA->getElementType().getTypePtr())) 790 Block = addStmt(VA->getSizeExpr()); 791 792 return Block; 793} 794 795CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 796 // We may see an if statement in the middle of a basic block, or it may be the 797 // first statement we are processing. In either case, we create a new basic 798 // block. First, we create the blocks for the then...else statements, and 799 // then we create the block containing the if statement. If we were in the 800 // middle of a block, we stop processing that block. That block is then the 801 // implicit successor for the "then" and "else" clauses. 802 803 // The block we were proccessing is now finished. Make it the successor 804 // block. 805 if (Block) { 806 Succ = Block; 807 if (!FinishBlock(Block)) 808 return 0; 809 } 810 811 // Process the false branch. 812 CFGBlock* ElseBlock = Succ; 813 814 if (Stmt* Else = I->getElse()) { 815 SaveAndRestore<CFGBlock*> sv(Succ); 816 817 // NULL out Block so that the recursive call to Visit will 818 // create a new basic block. 819 Block = NULL; 820 ElseBlock = addStmt(Else); 821 822 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 823 ElseBlock = sv.get(); 824 else if (Block) { 825 if (!FinishBlock(ElseBlock)) 826 return 0; 827 } 828 } 829 830 // Process the true branch. 831 CFGBlock* ThenBlock; 832 { 833 Stmt* Then = I->getThen(); 834 assert(Then); 835 SaveAndRestore<CFGBlock*> sv(Succ); 836 Block = NULL; 837 ThenBlock = addStmt(Then); 838 839 if (!ThenBlock) { 840 // We can reach here if the "then" body has all NullStmts. 841 // Create an empty block so we can distinguish between true and false 842 // branches in path-sensitive analyses. 843 ThenBlock = createBlock(false); 844 AddSuccessor(ThenBlock, sv.get()); 845 } else if (Block) { 846 if (!FinishBlock(ThenBlock)) 847 return 0; 848 } 849 } 850 851 // Now create a new block containing the if statement. 852 Block = createBlock(false); 853 854 // Set the terminator of the new block to the If statement. 855 Block->setTerminator(I); 856 857 // See if this is a known constant. 858 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 859 860 // Now add the successors. 861 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 862 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 863 864 // Add the condition as the last statement in the new block. This may create 865 // new blocks as the condition may contain control-flow. Any newly created 866 // blocks will be pointed to be "Block". 867 Block = addStmt(I->getCond()); 868 869 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 870 // and the condition variable initialization to the CFG. 871 if (VarDecl *VD = I->getConditionVariable()) { 872 if (Expr *Init = VD->getInit()) { 873 autoCreateBlock(); 874 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 875 addStmt(Init); 876 } 877 } 878 879 return Block; 880} 881 882 883CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 884 // If we were in the middle of a block we stop processing that block. 885 // 886 // NOTE: If a "return" appears in the middle of a block, this means that the 887 // code afterwards is DEAD (unreachable). We still keep a basic block 888 // for that code; a simple "mark-and-sweep" from the entry block will be 889 // able to report such dead blocks. 890 if (Block) 891 FinishBlock(Block); 892 893 // Create the new block. 894 Block = createBlock(false); 895 896 // The Exit block is the only successor. 897 AddSuccessor(Block, &cfg->getExit()); 898 899 // Add the return statement to the block. This may create new blocks if R 900 // contains control-flow (short-circuit operations). 901 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 902} 903 904CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 905 // Get the block of the labeled statement. Add it to our map. 906 addStmt(L->getSubStmt()); 907 CFGBlock* LabelBlock = Block; 908 909 if (!LabelBlock) // This can happen when the body is empty, i.e. 910 LabelBlock = createBlock(); // scopes that only contains NullStmts. 911 912 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 913 LabelMap[ L ] = LabelBlock; 914 915 // Labels partition blocks, so this is the end of the basic block we were 916 // processing (L is the block's label). Because this is label (and we have 917 // already processed the substatement) there is no extra control-flow to worry 918 // about. 919 LabelBlock->setLabel(L); 920 if (!FinishBlock(LabelBlock)) 921 return 0; 922 923 // We set Block to NULL to allow lazy creation of a new block (if necessary); 924 Block = NULL; 925 926 // This block is now the implicit successor of other blocks. 927 Succ = LabelBlock; 928 929 return LabelBlock; 930} 931 932CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 933 // Goto is a control-flow statement. Thus we stop processing the current 934 // block and create a new one. 935 if (Block) 936 FinishBlock(Block); 937 938 Block = createBlock(false); 939 Block->setTerminator(G); 940 941 // If we already know the mapping to the label block add the successor now. 942 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 943 944 if (I == LabelMap.end()) 945 // We will need to backpatch this block later. 946 BackpatchBlocks.push_back(Block); 947 else 948 AddSuccessor(Block, I->second); 949 950 return Block; 951} 952 953CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 954 CFGBlock* LoopSuccessor = NULL; 955 956 // "for" is a control-flow statement. Thus we stop processing the current 957 // block. 958 if (Block) { 959 if (!FinishBlock(Block)) 960 return 0; 961 LoopSuccessor = Block; 962 } else 963 LoopSuccessor = Succ; 964 965 // Because of short-circuit evaluation, the condition of the loop can span 966 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 967 // evaluate the condition. 968 CFGBlock* ExitConditionBlock = createBlock(false); 969 CFGBlock* EntryConditionBlock = ExitConditionBlock; 970 971 // Set the terminator for the "exit" condition block. 972 ExitConditionBlock->setTerminator(F); 973 974 // Now add the actual condition to the condition block. Because the condition 975 // itself may contain control-flow, new blocks may be created. 976 if (Stmt* C = F->getCond()) { 977 Block = ExitConditionBlock; 978 EntryConditionBlock = addStmt(C); 979 assert(Block == EntryConditionBlock); 980 981 // If this block contains a condition variable, add both the condition 982 // variable and initializer to the CFG. 983 if (VarDecl *VD = F->getConditionVariable()) { 984 if (Expr *Init = VD->getInit()) { 985 autoCreateBlock(); 986 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 987 EntryConditionBlock = addStmt(Init); 988 assert(Block == EntryConditionBlock); 989 } 990 } 991 992 if (Block) { 993 if (!FinishBlock(EntryConditionBlock)) 994 return 0; 995 } 996 } 997 998 // The condition block is the implicit successor for the loop body as well as 999 // any code above the loop. 1000 Succ = EntryConditionBlock; 1001 1002 // See if this is a known constant. 1003 TryResult KnownVal(true); 1004 1005 if (F->getCond()) 1006 KnownVal = TryEvaluateBool(F->getCond()); 1007 1008 // Now create the loop body. 1009 { 1010 assert(F->getBody()); 1011 1012 // Save the current values for Block, Succ, and continue and break targets 1013 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1014 save_continue(ContinueTargetBlock), 1015 save_break(BreakTargetBlock); 1016 1017 // Create a new block to contain the (bottom) of the loop body. 1018 Block = NULL; 1019 1020 if (Stmt* I = F->getInc()) { 1021 // Generate increment code in its own basic block. This is the target of 1022 // continue statements. 1023 Succ = addStmt(I); 1024 } else { 1025 // No increment code. Create a special, empty, block that is used as the 1026 // target block for "looping back" to the start of the loop. 1027 assert(Succ == EntryConditionBlock); 1028 Succ = createBlock(); 1029 } 1030 1031 // Finish up the increment (or empty) block if it hasn't been already. 1032 if (Block) { 1033 assert(Block == Succ); 1034 if (!FinishBlock(Block)) 1035 return 0; 1036 Block = 0; 1037 } 1038 1039 ContinueTargetBlock = Succ; 1040 1041 // The starting block for the loop increment is the block that should 1042 // represent the 'loop target' for looping back to the start of the loop. 1043 ContinueTargetBlock->setLoopTarget(F); 1044 1045 // All breaks should go to the code following the loop. 1046 BreakTargetBlock = LoopSuccessor; 1047 1048 // Now populate the body block, and in the process create new blocks as we 1049 // walk the body of the loop. 1050 CFGBlock* BodyBlock = addStmt(F->getBody()); 1051 1052 if (!BodyBlock) 1053 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1054 else if (Block && !FinishBlock(BodyBlock)) 1055 return 0; 1056 1057 // This new body block is a successor to our "exit" condition block. 1058 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1059 } 1060 1061 // Link up the condition block with the code that follows the loop. (the 1062 // false branch). 1063 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1064 1065 // If the loop contains initialization, create a new block for those 1066 // statements. This block can also contain statements that precede the loop. 1067 if (Stmt* I = F->getInit()) { 1068 Block = createBlock(); 1069 return addStmt(I); 1070 } else { 1071 // There is no loop initialization. We are thus basically a while loop. 1072 // NULL out Block to force lazy block construction. 1073 Block = NULL; 1074 Succ = EntryConditionBlock; 1075 return EntryConditionBlock; 1076 } 1077} 1078 1079CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1080 // Objective-C fast enumeration 'for' statements: 1081 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1082 // 1083 // for ( Type newVariable in collection_expression ) { statements } 1084 // 1085 // becomes: 1086 // 1087 // prologue: 1088 // 1. collection_expression 1089 // T. jump to loop_entry 1090 // loop_entry: 1091 // 1. side-effects of element expression 1092 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1093 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1094 // TB: 1095 // statements 1096 // T. jump to loop_entry 1097 // FB: 1098 // what comes after 1099 // 1100 // and 1101 // 1102 // Type existingItem; 1103 // for ( existingItem in expression ) { statements } 1104 // 1105 // becomes: 1106 // 1107 // the same with newVariable replaced with existingItem; the binding works 1108 // the same except that for one ObjCForCollectionStmt::getElement() returns 1109 // a DeclStmt and the other returns a DeclRefExpr. 1110 // 1111 1112 CFGBlock* LoopSuccessor = 0; 1113 1114 if (Block) { 1115 if (!FinishBlock(Block)) 1116 return 0; 1117 LoopSuccessor = Block; 1118 Block = 0; 1119 } else 1120 LoopSuccessor = Succ; 1121 1122 // Build the condition blocks. 1123 CFGBlock* ExitConditionBlock = createBlock(false); 1124 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1125 1126 // Set the terminator for the "exit" condition block. 1127 ExitConditionBlock->setTerminator(S); 1128 1129 // The last statement in the block should be the ObjCForCollectionStmt, which 1130 // performs the actual binding to 'element' and determines if there are any 1131 // more items in the collection. 1132 AppendStmt(ExitConditionBlock, S); 1133 Block = ExitConditionBlock; 1134 1135 // Walk the 'element' expression to see if there are any side-effects. We 1136 // generate new blocks as necesary. We DON'T add the statement by default to 1137 // the CFG unless it contains control-flow. 1138 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1139 if (Block) { 1140 if (!FinishBlock(EntryConditionBlock)) 1141 return 0; 1142 Block = 0; 1143 } 1144 1145 // The condition block is the implicit successor for the loop body as well as 1146 // any code above the loop. 1147 Succ = EntryConditionBlock; 1148 1149 // Now create the true branch. 1150 { 1151 // Save the current values for Succ, continue and break targets. 1152 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1153 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1154 1155 BreakTargetBlock = LoopSuccessor; 1156 ContinueTargetBlock = EntryConditionBlock; 1157 1158 CFGBlock* BodyBlock = addStmt(S->getBody()); 1159 1160 if (!BodyBlock) 1161 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1162 else if (Block) { 1163 if (!FinishBlock(BodyBlock)) 1164 return 0; 1165 } 1166 1167 // This new body block is a successor to our "exit" condition block. 1168 AddSuccessor(ExitConditionBlock, BodyBlock); 1169 } 1170 1171 // Link up the condition block with the code that follows the loop. 1172 // (the false branch). 1173 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1174 1175 // Now create a prologue block to contain the collection expression. 1176 Block = createBlock(); 1177 return addStmt(S->getCollection()); 1178} 1179 1180CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1181 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1182 1183 // Inline the body. 1184 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1185 1186 // The sync body starts its own basic block. This makes it a little easier 1187 // for diagnostic clients. 1188 if (SyncBlock) { 1189 if (!FinishBlock(SyncBlock)) 1190 return 0; 1191 1192 Block = 0; 1193 } 1194 1195 Succ = SyncBlock; 1196 1197 // Inline the sync expression. 1198 return addStmt(S->getSynchExpr()); 1199} 1200 1201CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1202 // FIXME 1203 return NYS(); 1204} 1205 1206CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1207 CFGBlock* LoopSuccessor = NULL; 1208 1209 // "while" is a control-flow statement. Thus we stop processing the current 1210 // block. 1211 if (Block) { 1212 if (!FinishBlock(Block)) 1213 return 0; 1214 LoopSuccessor = Block; 1215 } else 1216 LoopSuccessor = Succ; 1217 1218 // Because of short-circuit evaluation, the condition of the loop can span 1219 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1220 // evaluate the condition. 1221 CFGBlock* ExitConditionBlock = createBlock(false); 1222 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1223 1224 // Set the terminator for the "exit" condition block. 1225 ExitConditionBlock->setTerminator(W); 1226 1227 // Now add the actual condition to the condition block. Because the condition 1228 // itself may contain control-flow, new blocks may be created. Thus we update 1229 // "Succ" after adding the condition. 1230 if (Stmt* C = W->getCond()) { 1231 Block = ExitConditionBlock; 1232 EntryConditionBlock = addStmt(C); 1233 assert(Block == EntryConditionBlock); 1234 1235 // If this block contains a condition variable, add both the condition 1236 // variable and initializer to the CFG. 1237 if (VarDecl *VD = W->getConditionVariable()) { 1238 if (Expr *Init = VD->getInit()) { 1239 autoCreateBlock(); 1240 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1241 EntryConditionBlock = addStmt(Init); 1242 assert(Block == EntryConditionBlock); 1243 } 1244 } 1245 1246 if (Block) { 1247 if (!FinishBlock(EntryConditionBlock)) 1248 return 0; 1249 } 1250 } 1251 1252 // The condition block is the implicit successor for the loop body as well as 1253 // any code above the loop. 1254 Succ = EntryConditionBlock; 1255 1256 // See if this is a known constant. 1257 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1258 1259 // Process the loop body. 1260 { 1261 assert(W->getBody()); 1262 1263 // Save the current values for Block, Succ, and continue and break targets 1264 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1265 save_continue(ContinueTargetBlock), 1266 save_break(BreakTargetBlock); 1267 1268 // Create an empty block to represent the transition block for looping back 1269 // to the head of the loop. 1270 Block = 0; 1271 assert(Succ == EntryConditionBlock); 1272 Succ = createBlock(); 1273 Succ->setLoopTarget(W); 1274 ContinueTargetBlock = Succ; 1275 1276 // All breaks should go to the code following the loop. 1277 BreakTargetBlock = LoopSuccessor; 1278 1279 // NULL out Block to force lazy instantiation of blocks for the body. 1280 Block = NULL; 1281 1282 // Create the body. The returned block is the entry to the loop body. 1283 CFGBlock* BodyBlock = addStmt(W->getBody()); 1284 1285 if (!BodyBlock) 1286 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1287 else if (Block) { 1288 if (!FinishBlock(BodyBlock)) 1289 return 0; 1290 } 1291 1292 // Add the loop body entry as a successor to the condition. 1293 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1294 } 1295 1296 // Link up the condition block with the code that follows the loop. (the 1297 // false branch). 1298 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1299 1300 // There can be no more statements in the condition block since we loop back 1301 // to this block. NULL out Block to force lazy creation of another block. 1302 Block = NULL; 1303 1304 // Return the condition block, which is the dominating block for the loop. 1305 Succ = EntryConditionBlock; 1306 return EntryConditionBlock; 1307} 1308 1309 1310CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1311 // FIXME: For now we pretend that @catch and the code it contains does not 1312 // exit. 1313 return Block; 1314} 1315 1316CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1317 // FIXME: This isn't complete. We basically treat @throw like a return 1318 // statement. 1319 1320 // If we were in the middle of a block we stop processing that block. 1321 if (Block && !FinishBlock(Block)) 1322 return 0; 1323 1324 // Create the new block. 1325 Block = createBlock(false); 1326 1327 // The Exit block is the only successor. 1328 AddSuccessor(Block, &cfg->getExit()); 1329 1330 // Add the statement to the block. This may create new blocks if S contains 1331 // control-flow (short-circuit operations). 1332 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1333} 1334 1335CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1336 // If we were in the middle of a block we stop processing that block. 1337 if (Block && !FinishBlock(Block)) 1338 return 0; 1339 1340 // Create the new block. 1341 Block = createBlock(false); 1342 1343 if (TryTerminatedBlock) 1344 // The current try statement is the only successor. 1345 AddSuccessor(Block, TryTerminatedBlock); 1346 else 1347 // otherwise the Exit block is the only successor. 1348 AddSuccessor(Block, &cfg->getExit()); 1349 1350 // Add the statement to the block. This may create new blocks if S contains 1351 // control-flow (short-circuit operations). 1352 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1353} 1354 1355CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1356 CFGBlock* LoopSuccessor = NULL; 1357 1358 // "do...while" is a control-flow statement. Thus we stop processing the 1359 // current block. 1360 if (Block) { 1361 if (!FinishBlock(Block)) 1362 return 0; 1363 LoopSuccessor = Block; 1364 } else 1365 LoopSuccessor = Succ; 1366 1367 // Because of short-circuit evaluation, the condition of the loop can span 1368 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1369 // evaluate the condition. 1370 CFGBlock* ExitConditionBlock = createBlock(false); 1371 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1372 1373 // Set the terminator for the "exit" condition block. 1374 ExitConditionBlock->setTerminator(D); 1375 1376 // Now add the actual condition to the condition block. Because the condition 1377 // itself may contain control-flow, new blocks may be created. 1378 if (Stmt* C = D->getCond()) { 1379 Block = ExitConditionBlock; 1380 EntryConditionBlock = addStmt(C); 1381 if (Block) { 1382 if (!FinishBlock(EntryConditionBlock)) 1383 return 0; 1384 } 1385 } 1386 1387 // The condition block is the implicit successor for the loop body. 1388 Succ = EntryConditionBlock; 1389 1390 // See if this is a known constant. 1391 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1392 1393 // Process the loop body. 1394 CFGBlock* BodyBlock = NULL; 1395 { 1396 assert(D->getBody()); 1397 1398 // Save the current values for Block, Succ, and continue and break targets 1399 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1400 save_continue(ContinueTargetBlock), 1401 save_break(BreakTargetBlock); 1402 1403 // All continues within this loop should go to the condition block 1404 ContinueTargetBlock = EntryConditionBlock; 1405 1406 // All breaks should go to the code following the loop. 1407 BreakTargetBlock = LoopSuccessor; 1408 1409 // NULL out Block to force lazy instantiation of blocks for the body. 1410 Block = NULL; 1411 1412 // Create the body. The returned block is the entry to the loop body. 1413 BodyBlock = addStmt(D->getBody()); 1414 1415 if (!BodyBlock) 1416 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1417 else if (Block) { 1418 if (!FinishBlock(BodyBlock)) 1419 return 0; 1420 } 1421 1422 // Add an intermediate block between the BodyBlock and the 1423 // ExitConditionBlock to represent the "loop back" transition. Create an 1424 // empty block to represent the transition block for looping back to the 1425 // head of the loop. 1426 // FIXME: Can we do this more efficiently without adding another block? 1427 Block = NULL; 1428 Succ = BodyBlock; 1429 CFGBlock *LoopBackBlock = createBlock(); 1430 LoopBackBlock->setLoopTarget(D); 1431 1432 // Add the loop body entry as a successor to the condition. 1433 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : LoopBackBlock); 1434 } 1435 1436 // Link up the condition block with the code that follows the loop. 1437 // (the false branch). 1438 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1439 1440 // There can be no more statements in the body block(s) since we loop back to 1441 // the body. NULL out Block to force lazy creation of another block. 1442 Block = NULL; 1443 1444 // Return the loop body, which is the dominating block for the loop. 1445 Succ = BodyBlock; 1446 return BodyBlock; 1447} 1448 1449CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1450 // "continue" is a control-flow statement. Thus we stop processing the 1451 // current block. 1452 if (Block && !FinishBlock(Block)) 1453 return 0; 1454 1455 // Now create a new block that ends with the continue statement. 1456 Block = createBlock(false); 1457 Block->setTerminator(C); 1458 1459 // If there is no target for the continue, then we are looking at an 1460 // incomplete AST. This means the CFG cannot be constructed. 1461 if (ContinueTargetBlock) 1462 AddSuccessor(Block, ContinueTargetBlock); 1463 else 1464 badCFG = true; 1465 1466 return Block; 1467} 1468 1469CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1470 AddStmtChoice asc) { 1471 1472 if (asc.alwaysAdd()) { 1473 autoCreateBlock(); 1474 AppendStmt(Block, E); 1475 } 1476 1477 // VLA types have expressions that must be evaluated. 1478 if (E->isArgumentType()) { 1479 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1480 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1481 addStmt(VA->getSizeExpr()); 1482 } 1483 1484 return Block; 1485} 1486 1487/// VisitStmtExpr - Utility method to handle (nested) statement 1488/// expressions (a GCC extension). 1489CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1490 if (asc.alwaysAdd()) { 1491 autoCreateBlock(); 1492 AppendStmt(Block, SE); 1493 } 1494 return VisitCompoundStmt(SE->getSubStmt()); 1495} 1496 1497CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1498 // "switch" is a control-flow statement. Thus we stop processing the current 1499 // block. 1500 CFGBlock* SwitchSuccessor = NULL; 1501 1502 if (Block) { 1503 if (!FinishBlock(Block)) 1504 return 0; 1505 SwitchSuccessor = Block; 1506 } else SwitchSuccessor = Succ; 1507 1508 // Save the current "switch" context. 1509 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1510 save_break(BreakTargetBlock), 1511 save_default(DefaultCaseBlock); 1512 1513 // Set the "default" case to be the block after the switch statement. If the 1514 // switch statement contains a "default:", this value will be overwritten with 1515 // the block for that code. 1516 DefaultCaseBlock = SwitchSuccessor; 1517 1518 // Create a new block that will contain the switch statement. 1519 SwitchTerminatedBlock = createBlock(false); 1520 1521 // Now process the switch body. The code after the switch is the implicit 1522 // successor. 1523 Succ = SwitchSuccessor; 1524 BreakTargetBlock = SwitchSuccessor; 1525 1526 // When visiting the body, the case statements should automatically get linked 1527 // up to the switch. We also don't keep a pointer to the body, since all 1528 // control-flow from the switch goes to case/default statements. 1529 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1530 Block = NULL; 1531 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1532 if (Block) { 1533 if (!FinishBlock(BodyBlock)) 1534 return 0; 1535 } 1536 1537 // If we have no "default:" case, the default transition is to the code 1538 // following the switch body. 1539 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1540 1541 // Add the terminator and condition in the switch block. 1542 SwitchTerminatedBlock->setTerminator(Terminator); 1543 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1544 Block = SwitchTerminatedBlock; 1545 Block = addStmt(Terminator->getCond()); 1546 1547 // Finally, if the SwitchStmt contains a condition variable, add both the 1548 // SwitchStmt and the condition variable initialization to the CFG. 1549 if (VarDecl *VD = Terminator->getConditionVariable()) { 1550 if (Expr *Init = VD->getInit()) { 1551 autoCreateBlock(); 1552 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1553 addStmt(Init); 1554 } 1555 } 1556 1557 return Block; 1558} 1559 1560CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1561 // CaseStmts are essentially labels, so they are the first statement in a 1562 // block. 1563 1564 if (CS->getSubStmt()) 1565 addStmt(CS->getSubStmt()); 1566 1567 CFGBlock* CaseBlock = Block; 1568 if (!CaseBlock) 1569 CaseBlock = createBlock(); 1570 1571 // Cases statements partition blocks, so this is the top of the basic block we 1572 // were processing (the "case XXX:" is the label). 1573 CaseBlock->setLabel(CS); 1574 1575 if (!FinishBlock(CaseBlock)) 1576 return 0; 1577 1578 // Add this block to the list of successors for the block with the switch 1579 // statement. 1580 assert(SwitchTerminatedBlock); 1581 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1582 1583 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1584 Block = NULL; 1585 1586 // This block is now the implicit successor of other blocks. 1587 Succ = CaseBlock; 1588 1589 return CaseBlock; 1590} 1591 1592CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1593 if (Terminator->getSubStmt()) 1594 addStmt(Terminator->getSubStmt()); 1595 1596 DefaultCaseBlock = Block; 1597 1598 if (!DefaultCaseBlock) 1599 DefaultCaseBlock = createBlock(); 1600 1601 // Default statements partition blocks, so this is the top of the basic block 1602 // we were processing (the "default:" is the label). 1603 DefaultCaseBlock->setLabel(Terminator); 1604 1605 if (!FinishBlock(DefaultCaseBlock)) 1606 return 0; 1607 1608 // Unlike case statements, we don't add the default block to the successors 1609 // for the switch statement immediately. This is done when we finish 1610 // processing the switch statement. This allows for the default case 1611 // (including a fall-through to the code after the switch statement) to always 1612 // be the last successor of a switch-terminated block. 1613 1614 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1615 Block = NULL; 1616 1617 // This block is now the implicit successor of other blocks. 1618 Succ = DefaultCaseBlock; 1619 1620 return DefaultCaseBlock; 1621} 1622 1623CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1624 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1625 // current block. 1626 CFGBlock* TrySuccessor = NULL; 1627 1628 if (Block) { 1629 if (!FinishBlock(Block)) 1630 return 0; 1631 TrySuccessor = Block; 1632 } else TrySuccessor = Succ; 1633 1634 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1635 1636 // Create a new block that will contain the try statement. 1637 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1638 // Add the terminator in the try block. 1639 NewTryTerminatedBlock->setTerminator(Terminator); 1640 1641 bool HasCatchAll = false; 1642 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1643 // The code after the try is the implicit successor. 1644 Succ = TrySuccessor; 1645 CXXCatchStmt *CS = Terminator->getHandler(h); 1646 if (CS->getExceptionDecl() == 0) { 1647 HasCatchAll = true; 1648 } 1649 Block = NULL; 1650 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1651 if (CatchBlock == 0) 1652 return 0; 1653 // Add this block to the list of successors for the block with the try 1654 // statement. 1655 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1656 } 1657 if (!HasCatchAll) { 1658 if (PrevTryTerminatedBlock) 1659 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1660 else 1661 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1662 } 1663 1664 // The code after the try is the implicit successor. 1665 Succ = TrySuccessor; 1666 1667 // Save the current "try" context. 1668 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1669 TryTerminatedBlock = NewTryTerminatedBlock; 1670 1671 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1672 Block = NULL; 1673 Block = addStmt(Terminator->getTryBlock()); 1674 return Block; 1675} 1676 1677CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1678 // CXXCatchStmt are treated like labels, so they are the first statement in a 1679 // block. 1680 1681 if (CS->getHandlerBlock()) 1682 addStmt(CS->getHandlerBlock()); 1683 1684 CFGBlock* CatchBlock = Block; 1685 if (!CatchBlock) 1686 CatchBlock = createBlock(); 1687 1688 CatchBlock->setLabel(CS); 1689 1690 if (!FinishBlock(CatchBlock)) 1691 return 0; 1692 1693 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1694 Block = NULL; 1695 1696 return CatchBlock; 1697} 1698 1699CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1700 // Lazily create the indirect-goto dispatch block if there isn't one already. 1701 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1702 1703 if (!IBlock) { 1704 IBlock = createBlock(false); 1705 cfg->setIndirectGotoBlock(IBlock); 1706 } 1707 1708 // IndirectGoto is a control-flow statement. Thus we stop processing the 1709 // current block and create a new one. 1710 if (Block && !FinishBlock(Block)) 1711 return 0; 1712 1713 Block = createBlock(false); 1714 Block->setTerminator(I); 1715 AddSuccessor(Block, IBlock); 1716 return addStmt(I->getTarget()); 1717} 1718 1719} // end anonymous namespace 1720 1721/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1722/// no successors or predecessors. If this is the first block created in the 1723/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1724CFGBlock* CFG::createBlock() { 1725 bool first_block = begin() == end(); 1726 1727 // Create the block. 1728 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1729 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1730 Blocks.push_back(Mem, BlkBVC); 1731 1732 // If this is the first block, set it as the Entry and Exit. 1733 if (first_block) 1734 Entry = Exit = &back(); 1735 1736 // Return the block. 1737 return &back(); 1738} 1739 1740/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1741/// CFG is returned to the caller. 1742CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1743 bool AddEHEdges, bool AddScopes) { 1744 CFGBuilder Builder; 1745 return Builder.buildCFG(D, Statement, C, AddEHEdges, AddScopes); 1746} 1747 1748//===----------------------------------------------------------------------===// 1749// CFG: Queries for BlkExprs. 1750//===----------------------------------------------------------------------===// 1751 1752namespace { 1753 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1754} 1755 1756static void FindSubExprAssignments(Stmt *S, 1757 llvm::SmallPtrSet<Expr*,50>& Set) { 1758 if (!S) 1759 return; 1760 1761 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1762 Stmt *child = *I; 1763 if (!child) 1764 continue; 1765 1766 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1767 if (B->isAssignmentOp()) Set.insert(B); 1768 1769 FindSubExprAssignments(child, Set); 1770 } 1771} 1772 1773static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1774 BlkExprMapTy* M = new BlkExprMapTy(); 1775 1776 // Look for assignments that are used as subexpressions. These are the only 1777 // assignments that we want to *possibly* register as a block-level 1778 // expression. Basically, if an assignment occurs both in a subexpression and 1779 // at the block-level, it is a block-level expression. 1780 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1781 1782 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1783 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1784 FindSubExprAssignments(*BI, SubExprAssignments); 1785 1786 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1787 1788 // Iterate over the statements again on identify the Expr* and Stmt* at the 1789 // block-level that are block-level expressions. 1790 1791 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1792 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1793 1794 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1795 // Assignment expressions that are not nested within another 1796 // expression are really "statements" whose value is never used by 1797 // another expression. 1798 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1799 continue; 1800 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1801 // Special handling for statement expressions. The last statement in 1802 // the statement expression is also a block-level expr. 1803 const CompoundStmt* C = Terminator->getSubStmt(); 1804 if (!C->body_empty()) { 1805 unsigned x = M->size(); 1806 (*M)[C->body_back()] = x; 1807 } 1808 } 1809 1810 unsigned x = M->size(); 1811 (*M)[Exp] = x; 1812 } 1813 1814 // Look at terminators. The condition is a block-level expression. 1815 1816 Stmt* S = (*I)->getTerminatorCondition(); 1817 1818 if (S && M->find(S) == M->end()) { 1819 unsigned x = M->size(); 1820 (*M)[S] = x; 1821 } 1822 } 1823 1824 return M; 1825} 1826 1827CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1828 assert(S != NULL); 1829 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1830 1831 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1832 BlkExprMapTy::iterator I = M->find(S); 1833 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1834} 1835 1836unsigned CFG::getNumBlkExprs() { 1837 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1838 return M->size(); 1839 else { 1840 // We assume callers interested in the number of BlkExprs will want 1841 // the map constructed if it doesn't already exist. 1842 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1843 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1844 } 1845} 1846 1847//===----------------------------------------------------------------------===// 1848// Cleanup: CFG dstor. 1849//===----------------------------------------------------------------------===// 1850 1851CFG::~CFG() { 1852 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1853} 1854 1855//===----------------------------------------------------------------------===// 1856// CFG pretty printing 1857//===----------------------------------------------------------------------===// 1858 1859namespace { 1860 1861class StmtPrinterHelper : public PrinterHelper { 1862 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1863 StmtMapTy StmtMap; 1864 signed CurrentBlock; 1865 unsigned CurrentStmt; 1866 const LangOptions &LangOpts; 1867public: 1868 1869 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1870 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1871 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1872 unsigned j = 1; 1873 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1874 BI != BEnd; ++BI, ++j ) 1875 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1876 } 1877 } 1878 1879 virtual ~StmtPrinterHelper() {} 1880 1881 const LangOptions &getLangOpts() const { return LangOpts; } 1882 void setBlockID(signed i) { CurrentBlock = i; } 1883 void setStmtID(unsigned i) { CurrentStmt = i; } 1884 1885 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1886 1887 StmtMapTy::iterator I = StmtMap.find(Terminator); 1888 1889 if (I == StmtMap.end()) 1890 return false; 1891 1892 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 1893 && I->second.second == CurrentStmt) { 1894 return false; 1895 } 1896 1897 OS << "[B" << I->second.first << "." << I->second.second << "]"; 1898 return true; 1899 } 1900}; 1901} // end anonymous namespace 1902 1903 1904namespace { 1905class CFGBlockTerminatorPrint 1906 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 1907 1908 llvm::raw_ostream& OS; 1909 StmtPrinterHelper* Helper; 1910 PrintingPolicy Policy; 1911public: 1912 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 1913 const PrintingPolicy &Policy) 1914 : OS(os), Helper(helper), Policy(Policy) {} 1915 1916 void VisitIfStmt(IfStmt* I) { 1917 OS << "if "; 1918 I->getCond()->printPretty(OS,Helper,Policy); 1919 } 1920 1921 // Default case. 1922 void VisitStmt(Stmt* Terminator) { 1923 Terminator->printPretty(OS, Helper, Policy); 1924 } 1925 1926 void VisitForStmt(ForStmt* F) { 1927 OS << "for (" ; 1928 if (F->getInit()) 1929 OS << "..."; 1930 OS << "; "; 1931 if (Stmt* C = F->getCond()) 1932 C->printPretty(OS, Helper, Policy); 1933 OS << "; "; 1934 if (F->getInc()) 1935 OS << "..."; 1936 OS << ")"; 1937 } 1938 1939 void VisitWhileStmt(WhileStmt* W) { 1940 OS << "while " ; 1941 if (Stmt* C = W->getCond()) 1942 C->printPretty(OS, Helper, Policy); 1943 } 1944 1945 void VisitDoStmt(DoStmt* D) { 1946 OS << "do ... while "; 1947 if (Stmt* C = D->getCond()) 1948 C->printPretty(OS, Helper, Policy); 1949 } 1950 1951 void VisitSwitchStmt(SwitchStmt* Terminator) { 1952 OS << "switch "; 1953 Terminator->getCond()->printPretty(OS, Helper, Policy); 1954 } 1955 1956 void VisitCXXTryStmt(CXXTryStmt* CS) { 1957 OS << "try ..."; 1958 } 1959 1960 void VisitConditionalOperator(ConditionalOperator* C) { 1961 C->getCond()->printPretty(OS, Helper, Policy); 1962 OS << " ? ... : ..."; 1963 } 1964 1965 void VisitChooseExpr(ChooseExpr* C) { 1966 OS << "__builtin_choose_expr( "; 1967 C->getCond()->printPretty(OS, Helper, Policy); 1968 OS << " )"; 1969 } 1970 1971 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1972 OS << "goto *"; 1973 I->getTarget()->printPretty(OS, Helper, Policy); 1974 } 1975 1976 void VisitBinaryOperator(BinaryOperator* B) { 1977 if (!B->isLogicalOp()) { 1978 VisitExpr(B); 1979 return; 1980 } 1981 1982 B->getLHS()->printPretty(OS, Helper, Policy); 1983 1984 switch (B->getOpcode()) { 1985 case BinaryOperator::LOr: 1986 OS << " || ..."; 1987 return; 1988 case BinaryOperator::LAnd: 1989 OS << " && ..."; 1990 return; 1991 default: 1992 assert(false && "Invalid logical operator."); 1993 } 1994 } 1995 1996 void VisitExpr(Expr* E) { 1997 E->printPretty(OS, Helper, Policy); 1998 } 1999}; 2000} // end anonymous namespace 2001 2002 2003static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2004 const CFGElement &E) { 2005 Stmt *Terminator = E; 2006 2007 if (E.asStartScope()) { 2008 OS << "start scope\n"; 2009 return; 2010 } 2011 if (E.asEndScope()) { 2012 OS << "end scope\n"; 2013 return; 2014 } 2015 2016 if (Helper) { 2017 // special printing for statement-expressions. 2018 if (StmtExpr* SE = dyn_cast<StmtExpr>(Terminator)) { 2019 CompoundStmt* Sub = SE->getSubStmt(); 2020 2021 if (Sub->child_begin() != Sub->child_end()) { 2022 OS << "({ ... ; "; 2023 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2024 OS << " })\n"; 2025 return; 2026 } 2027 } 2028 2029 // special printing for comma expressions. 2030 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Terminator)) { 2031 if (B->getOpcode() == BinaryOperator::Comma) { 2032 OS << "... , "; 2033 Helper->handledStmt(B->getRHS(),OS); 2034 OS << '\n'; 2035 return; 2036 } 2037 } 2038 } 2039 2040 Terminator->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2041 2042 // Expressions need a newline. 2043 if (isa<Expr>(Terminator)) OS << '\n'; 2044} 2045 2046static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2047 const CFGBlock& B, 2048 StmtPrinterHelper* Helper, bool print_edges) { 2049 2050 if (Helper) Helper->setBlockID(B.getBlockID()); 2051 2052 // Print the header. 2053 OS << "\n [ B" << B.getBlockID(); 2054 2055 if (&B == &cfg->getEntry()) 2056 OS << " (ENTRY) ]\n"; 2057 else if (&B == &cfg->getExit()) 2058 OS << " (EXIT) ]\n"; 2059 else if (&B == cfg->getIndirectGotoBlock()) 2060 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2061 else 2062 OS << " ]\n"; 2063 2064 // Print the label of this block. 2065 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2066 2067 if (print_edges) 2068 OS << " "; 2069 2070 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2071 OS << L->getName(); 2072 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2073 OS << "case "; 2074 C->getLHS()->printPretty(OS, Helper, 2075 PrintingPolicy(Helper->getLangOpts())); 2076 if (C->getRHS()) { 2077 OS << " ... "; 2078 C->getRHS()->printPretty(OS, Helper, 2079 PrintingPolicy(Helper->getLangOpts())); 2080 } 2081 } else if (isa<DefaultStmt>(Label)) 2082 OS << "default"; 2083 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2084 OS << "catch ("; 2085 if (CS->getExceptionDecl()) 2086 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2087 0); 2088 else 2089 OS << "..."; 2090 OS << ")"; 2091 2092 } else 2093 assert(false && "Invalid label statement in CFGBlock."); 2094 2095 OS << ":\n"; 2096 } 2097 2098 // Iterate through the statements in the block and print them. 2099 unsigned j = 1; 2100 2101 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2102 I != E ; ++I, ++j ) { 2103 2104 // Print the statement # in the basic block and the statement itself. 2105 if (print_edges) 2106 OS << " "; 2107 2108 OS << llvm::format("%3d", j) << ": "; 2109 2110 if (Helper) 2111 Helper->setStmtID(j); 2112 2113 print_stmt(OS,Helper,*I); 2114 } 2115 2116 // Print the terminator of this block. 2117 if (B.getTerminator()) { 2118 if (print_edges) 2119 OS << " "; 2120 2121 OS << " T: "; 2122 2123 if (Helper) Helper->setBlockID(-1); 2124 2125 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2126 PrintingPolicy(Helper->getLangOpts())); 2127 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2128 OS << '\n'; 2129 } 2130 2131 if (print_edges) { 2132 // Print the predecessors of this block. 2133 OS << " Predecessors (" << B.pred_size() << "):"; 2134 unsigned i = 0; 2135 2136 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2137 I != E; ++I, ++i) { 2138 2139 if (i == 8 || (i-8) == 0) 2140 OS << "\n "; 2141 2142 OS << " B" << (*I)->getBlockID(); 2143 } 2144 2145 OS << '\n'; 2146 2147 // Print the successors of this block. 2148 OS << " Successors (" << B.succ_size() << "):"; 2149 i = 0; 2150 2151 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2152 I != E; ++I, ++i) { 2153 2154 if (i == 8 || (i-8) % 10 == 0) 2155 OS << "\n "; 2156 2157 if (*I) 2158 OS << " B" << (*I)->getBlockID(); 2159 else 2160 OS << " NULL"; 2161 } 2162 2163 OS << '\n'; 2164 } 2165} 2166 2167 2168/// dump - A simple pretty printer of a CFG that outputs to stderr. 2169void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2170 2171/// print - A simple pretty printer of a CFG that outputs to an ostream. 2172void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2173 StmtPrinterHelper Helper(this, LO); 2174 2175 // Print the entry block. 2176 print_block(OS, this, getEntry(), &Helper, true); 2177 2178 // Iterate through the CFGBlocks and print them one by one. 2179 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2180 // Skip the entry block, because we already printed it. 2181 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2182 continue; 2183 2184 print_block(OS, this, **I, &Helper, true); 2185 } 2186 2187 // Print the exit block. 2188 print_block(OS, this, getExit(), &Helper, true); 2189 OS.flush(); 2190} 2191 2192/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2193void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2194 print(llvm::errs(), cfg, LO); 2195} 2196 2197/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2198/// Generally this will only be called from CFG::print. 2199void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2200 const LangOptions &LO) const { 2201 StmtPrinterHelper Helper(cfg, LO); 2202 print_block(OS, cfg, *this, &Helper, true); 2203} 2204 2205/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2206void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2207 const LangOptions &LO) const { 2208 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2209 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2210} 2211 2212Stmt* CFGBlock::getTerminatorCondition() { 2213 2214 if (!Terminator) 2215 return NULL; 2216 2217 Expr* E = NULL; 2218 2219 switch (Terminator->getStmtClass()) { 2220 default: 2221 break; 2222 2223 case Stmt::ForStmtClass: 2224 E = cast<ForStmt>(Terminator)->getCond(); 2225 break; 2226 2227 case Stmt::WhileStmtClass: 2228 E = cast<WhileStmt>(Terminator)->getCond(); 2229 break; 2230 2231 case Stmt::DoStmtClass: 2232 E = cast<DoStmt>(Terminator)->getCond(); 2233 break; 2234 2235 case Stmt::IfStmtClass: 2236 E = cast<IfStmt>(Terminator)->getCond(); 2237 break; 2238 2239 case Stmt::ChooseExprClass: 2240 E = cast<ChooseExpr>(Terminator)->getCond(); 2241 break; 2242 2243 case Stmt::IndirectGotoStmtClass: 2244 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2245 break; 2246 2247 case Stmt::SwitchStmtClass: 2248 E = cast<SwitchStmt>(Terminator)->getCond(); 2249 break; 2250 2251 case Stmt::ConditionalOperatorClass: 2252 E = cast<ConditionalOperator>(Terminator)->getCond(); 2253 break; 2254 2255 case Stmt::BinaryOperatorClass: // '&&' and '||' 2256 E = cast<BinaryOperator>(Terminator)->getLHS(); 2257 break; 2258 2259 case Stmt::ObjCForCollectionStmtClass: 2260 return Terminator; 2261 } 2262 2263 return E ? E->IgnoreParens() : NULL; 2264} 2265 2266bool CFGBlock::hasBinaryBranchTerminator() const { 2267 2268 if (!Terminator) 2269 return false; 2270 2271 Expr* E = NULL; 2272 2273 switch (Terminator->getStmtClass()) { 2274 default: 2275 return false; 2276 2277 case Stmt::ForStmtClass: 2278 case Stmt::WhileStmtClass: 2279 case Stmt::DoStmtClass: 2280 case Stmt::IfStmtClass: 2281 case Stmt::ChooseExprClass: 2282 case Stmt::ConditionalOperatorClass: 2283 case Stmt::BinaryOperatorClass: 2284 return true; 2285 } 2286 2287 return E ? E->IgnoreParens() : NULL; 2288} 2289 2290 2291//===----------------------------------------------------------------------===// 2292// CFG Graphviz Visualization 2293//===----------------------------------------------------------------------===// 2294 2295 2296#ifndef NDEBUG 2297static StmtPrinterHelper* GraphHelper; 2298#endif 2299 2300void CFG::viewCFG(const LangOptions &LO) const { 2301#ifndef NDEBUG 2302 StmtPrinterHelper H(this, LO); 2303 GraphHelper = &H; 2304 llvm::ViewGraph(this,"CFG"); 2305 GraphHelper = NULL; 2306#endif 2307} 2308 2309namespace llvm { 2310template<> 2311struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2312 2313 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2314 2315 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2316 2317#ifndef NDEBUG 2318 std::string OutSStr; 2319 llvm::raw_string_ostream Out(OutSStr); 2320 print_block(Out,Graph, *Node, GraphHelper, false); 2321 std::string& OutStr = Out.str(); 2322 2323 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2324 2325 // Process string output to make it nicer... 2326 for (unsigned i = 0; i != OutStr.length(); ++i) 2327 if (OutStr[i] == '\n') { // Left justify 2328 OutStr[i] = '\\'; 2329 OutStr.insert(OutStr.begin()+i+1, 'l'); 2330 } 2331 2332 return OutStr; 2333#else 2334 return ""; 2335#endif 2336 } 2337}; 2338} // end namespace llvm 2339