CFG.cpp revision 264ba48dc98f3f843935a485d5b086f7e0fdc4f1
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 >= AlwaysAddAsLValue; } 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, bool AddEHEdges, 103 bool AddScopes); 104 105private: 106 // Visitors to walk an AST and construct the CFG. 107 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc); 108 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc); 109 CFGBlock *VisitBlockExpr(BlockExpr* E, AddStmtChoice asc); 110 CFGBlock *VisitBreakStmt(BreakStmt *B); 111 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 112 CFGBlock *VisitCaseStmt(CaseStmt *C); 113 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 114 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 115 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, 116 AddStmtChoice asc); 117 CFGBlock *VisitContinueStmt(ContinueStmt *C); 118 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S); 119 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 120 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 121 CFGBlock *VisitDeclStmt(DeclStmt *DS); 122 CFGBlock *VisitDeclSubExpr(Decl* D); 123 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 124 CFGBlock *VisitDoStmt(DoStmt *D); 125 CFGBlock *VisitForStmt(ForStmt *F); 126 CFGBlock *VisitGotoStmt(GotoStmt* G); 127 CFGBlock *VisitIfStmt(IfStmt *I); 128 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 129 CFGBlock *VisitLabelStmt(LabelStmt *L); 130 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 131 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 132 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 133 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 134 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 135 CFGBlock *VisitReturnStmt(ReturnStmt* R); 136 CFGBlock *VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, AddStmtChoice asc); 137 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 138 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 139 CFGBlock *VisitWhileStmt(WhileStmt *W); 140 141 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 142 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 143 CFGBlock *VisitChildren(Stmt* S); 144 145 // NYS == Not Yet Supported 146 CFGBlock* NYS() { 147 badCFG = true; 148 return Block; 149 } 150 151 CFGBlock *StartScope(Stmt *S, CFGBlock *B) { 152 if (!AddScopes) 153 return B; 154 155 if (B == 0) 156 B = createBlock(); 157 B->StartScope(S, cfg->getBumpVectorContext()); 158 return B; 159 } 160 161 void EndScope(Stmt *S) { 162 if (!AddScopes) 163 return; 164 165 if (Block == 0) 166 Block = createBlock(); 167 Block->EndScope(S, cfg->getBumpVectorContext()); 168 } 169 170 void autoCreateBlock() { if (!Block) Block = createBlock(); } 171 CFGBlock *createBlock(bool add_successor = true); 172 bool FinishBlock(CFGBlock* B); 173 CFGBlock *addStmt(Stmt *S, AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 174 return Visit(S, asc); 175 } 176 177 void AppendStmt(CFGBlock *B, Stmt *S, 178 AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 179 B->appendStmt(S, cfg->getBumpVectorContext(), asc.asLValue()); 180 } 181 182 void AddSuccessor(CFGBlock *B, CFGBlock *S) { 183 B->addSuccessor(S, cfg->getBumpVectorContext()); 184 } 185 186 /// TryResult - a class representing a variant over the values 187 /// 'true', 'false', or 'unknown'. This is returned by TryEvaluateBool, 188 /// and is used by the CFGBuilder to decide if a branch condition 189 /// can be decided up front during CFG construction. 190 class TryResult { 191 int X; 192 public: 193 TryResult(bool b) : X(b ? 1 : 0) {} 194 TryResult() : X(-1) {} 195 196 bool isTrue() const { return X == 1; } 197 bool isFalse() const { return X == 0; } 198 bool isKnown() const { return X >= 0; } 199 void negate() { 200 assert(isKnown()); 201 X ^= 0x1; 202 } 203 }; 204 205 /// TryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 206 /// if we can evaluate to a known value, otherwise return -1. 207 TryResult TryEvaluateBool(Expr *S) { 208 Expr::EvalResult Result; 209 if (!S->isTypeDependent() && !S->isValueDependent() && 210 S->Evaluate(Result, *Context) && Result.Val.isInt()) 211 return Result.Val.getInt().getBoolValue(); 212 213 return TryResult(); 214 } 215 216 bool badCFG; 217 218 // True iff EH edges on CallExprs should be added to the CFG. 219 bool AddEHEdges; 220 221 // True iff scope start and scope end notes should be added to the CFG. 222 bool AddScopes; 223}; 224 225// FIXME: Add support for dependent-sized array types in C++? 226// Does it even make sense to build a CFG for an uninstantiated template? 227static VariableArrayType* FindVA(Type* t) { 228 while (ArrayType* vt = dyn_cast<ArrayType>(t)) { 229 if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt)) 230 if (vat->getSizeExpr()) 231 return vat; 232 233 t = vt->getElementType().getTypePtr(); 234 } 235 236 return 0; 237} 238 239/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 240/// arbitrary statement. Examples include a single expression or a function 241/// body (compound statement). The ownership of the returned CFG is 242/// transferred to the caller. If CFG construction fails, this method returns 243/// NULL. 244CFG* CFGBuilder::buildCFG(const Decl *D, Stmt* Statement, ASTContext* C, 245 bool addehedges, bool AddScopes) { 246 AddEHEdges = addehedges; 247 Context = C; 248 assert(cfg.get()); 249 if (!Statement) 250 return NULL; 251 252 this->AddScopes = AddScopes; 253 badCFG = false; 254 255 // Create an empty block that will serve as the exit block for the CFG. Since 256 // this is the first block added to the CFG, it will be implicitly registered 257 // as the exit block. 258 Succ = createBlock(); 259 assert(Succ == &cfg->getExit()); 260 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 261 262 // Visit the statements and create the CFG. 263 CFGBlock* B = addStmt(Statement); 264 265 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 266 // FIXME: Add code for base initializers and member initializers. 267 (void)CD; 268 } 269 if (!B) 270 B = Succ; 271 272 if (B) { 273 // Finalize the last constructed block. This usually involves reversing the 274 // order of the statements in the block. 275 if (Block) FinishBlock(B); 276 277 // Backpatch the gotos whose label -> block mappings we didn't know when we 278 // encountered them. 279 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 280 E = BackpatchBlocks.end(); I != E; ++I ) { 281 282 CFGBlock* B = *I; 283 GotoStmt* G = cast<GotoStmt>(B->getTerminator()); 284 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 285 286 // If there is no target for the goto, then we are looking at an 287 // incomplete AST. Handle this by not registering a successor. 288 if (LI == LabelMap.end()) continue; 289 290 AddSuccessor(B, LI->second); 291 } 292 293 // Add successors to the Indirect Goto Dispatch block (if we have one). 294 if (CFGBlock* B = cfg->getIndirectGotoBlock()) 295 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 296 E = AddressTakenLabels.end(); I != E; ++I ) { 297 298 // Lookup the target block. 299 LabelMapTy::iterator LI = LabelMap.find(*I); 300 301 // If there is no target block that contains label, then we are looking 302 // at an incomplete AST. Handle this by not registering a successor. 303 if (LI == LabelMap.end()) continue; 304 305 AddSuccessor(B, LI->second); 306 } 307 308 Succ = B; 309 } 310 311 // Create an empty entry block that has no predecessors. 312 cfg->setEntry(createBlock()); 313 314 return badCFG ? NULL : cfg.take(); 315} 316 317/// createBlock - Used to lazily create blocks that are connected 318/// to the current (global) succcessor. 319CFGBlock* CFGBuilder::createBlock(bool add_successor) { 320 CFGBlock* B = cfg->createBlock(); 321 if (add_successor && Succ) 322 AddSuccessor(B, Succ); 323 return B; 324} 325 326/// FinishBlock - "Finalize" the block by checking if we have a bad CFG. 327bool CFGBuilder::FinishBlock(CFGBlock* B) { 328 if (badCFG) 329 return false; 330 331 assert(B); 332 return true; 333} 334 335/// Visit - Walk the subtree of a statement and add extra 336/// blocks for ternary operators, &&, and ||. We also process "," and 337/// DeclStmts (which may contain nested control-flow). 338CFGBlock* CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 339tryAgain: 340 switch (S->getStmtClass()) { 341 default: 342 return VisitStmt(S, asc); 343 344 case Stmt::AddrLabelExprClass: 345 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 346 347 case Stmt::BinaryOperatorClass: 348 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 349 350 case Stmt::BlockExprClass: 351 return VisitBlockExpr(cast<BlockExpr>(S), asc); 352 353 case Stmt::BreakStmtClass: 354 return VisitBreakStmt(cast<BreakStmt>(S)); 355 356 case Stmt::CallExprClass: 357 return VisitCallExpr(cast<CallExpr>(S), asc); 358 359 case Stmt::CaseStmtClass: 360 return VisitCaseStmt(cast<CaseStmt>(S)); 361 362 case Stmt::ChooseExprClass: 363 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 364 365 case Stmt::CompoundStmtClass: 366 return VisitCompoundStmt(cast<CompoundStmt>(S)); 367 368 case Stmt::ConditionalOperatorClass: 369 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 370 371 case Stmt::ContinueStmtClass: 372 return VisitContinueStmt(cast<ContinueStmt>(S)); 373 374 case Stmt::CXXCatchStmtClass: 375 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 376 377 case Stmt::CXXThrowExprClass: 378 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 379 380 case Stmt::CXXTryStmtClass: 381 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 382 383 case Stmt::DeclStmtClass: 384 return VisitDeclStmt(cast<DeclStmt>(S)); 385 386 case Stmt::DefaultStmtClass: 387 return VisitDefaultStmt(cast<DefaultStmt>(S)); 388 389 case Stmt::DoStmtClass: 390 return VisitDoStmt(cast<DoStmt>(S)); 391 392 case Stmt::ForStmtClass: 393 return VisitForStmt(cast<ForStmt>(S)); 394 395 case Stmt::GotoStmtClass: 396 return VisitGotoStmt(cast<GotoStmt>(S)); 397 398 case Stmt::IfStmtClass: 399 return VisitIfStmt(cast<IfStmt>(S)); 400 401 case Stmt::IndirectGotoStmtClass: 402 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 403 404 case Stmt::LabelStmtClass: 405 return VisitLabelStmt(cast<LabelStmt>(S)); 406 407 case Stmt::ObjCAtCatchStmtClass: 408 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 409 410 case Stmt::ObjCAtSynchronizedStmtClass: 411 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 412 413 case Stmt::ObjCAtThrowStmtClass: 414 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 415 416 case Stmt::ObjCAtTryStmtClass: 417 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 418 419 case Stmt::ObjCForCollectionStmtClass: 420 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 421 422 case Stmt::ParenExprClass: 423 S = cast<ParenExpr>(S)->getSubExpr(); 424 goto tryAgain; 425 426 case Stmt::NullStmtClass: 427 return Block; 428 429 case Stmt::ReturnStmtClass: 430 return VisitReturnStmt(cast<ReturnStmt>(S)); 431 432 case Stmt::SizeOfAlignOfExprClass: 433 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 434 435 case Stmt::StmtExprClass: 436 return VisitStmtExpr(cast<StmtExpr>(S), asc); 437 438 case Stmt::SwitchStmtClass: 439 return VisitSwitchStmt(cast<SwitchStmt>(S)); 440 441 case Stmt::WhileStmtClass: 442 return VisitWhileStmt(cast<WhileStmt>(S)); 443 } 444} 445 446CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 447 if (asc.alwaysAdd()) { 448 autoCreateBlock(); 449 AppendStmt(Block, S, asc); 450 } 451 452 return VisitChildren(S); 453} 454 455/// VisitChildren - Visit the children of a Stmt. 456CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 457 CFGBlock *B = Block; 458 for (Stmt::child_iterator I = Terminator->child_begin(), 459 E = Terminator->child_end(); I != E; ++I) { 460 if (*I) B = Visit(*I); 461 } 462 return B; 463} 464 465CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 466 AddStmtChoice asc) { 467 AddressTakenLabels.insert(A->getLabel()); 468 469 if (asc.alwaysAdd()) { 470 autoCreateBlock(); 471 AppendStmt(Block, A, asc); 472 } 473 474 return Block; 475} 476 477CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 478 AddStmtChoice asc) { 479 if (B->isLogicalOp()) { // && or || 480 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 481 AppendStmt(ConfluenceBlock, B, asc); 482 483 if (!FinishBlock(ConfluenceBlock)) 484 return 0; 485 486 // create the block evaluating the LHS 487 CFGBlock* LHSBlock = createBlock(false); 488 LHSBlock->setTerminator(B); 489 490 // create the block evaluating the RHS 491 Succ = ConfluenceBlock; 492 Block = NULL; 493 CFGBlock* RHSBlock = addStmt(B->getRHS()); 494 if (!FinishBlock(RHSBlock)) 495 return 0; 496 497 // See if this is a known constant. 498 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 499 if (KnownVal.isKnown() && (B->getOpcode() == BinaryOperator::LOr)) 500 KnownVal.negate(); 501 502 // Now link the LHSBlock with RHSBlock. 503 if (B->getOpcode() == BinaryOperator::LOr) { 504 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 505 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 506 } else { 507 assert(B->getOpcode() == BinaryOperator::LAnd); 508 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 509 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 510 } 511 512 // Generate the blocks for evaluating the LHS. 513 Block = LHSBlock; 514 return addStmt(B->getLHS()); 515 } 516 else if (B->getOpcode() == BinaryOperator::Comma) { // , 517 autoCreateBlock(); 518 AppendStmt(Block, B, asc); 519 addStmt(B->getRHS()); 520 return addStmt(B->getLHS()); 521 } 522 523 return VisitStmt(B, asc); 524} 525 526CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 527 if (asc.alwaysAdd()) { 528 autoCreateBlock(); 529 AppendStmt(Block, E, asc); 530 } 531 return Block; 532} 533 534CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 535 // "break" is a control-flow statement. Thus we stop processing the current 536 // block. 537 if (Block && !FinishBlock(Block)) 538 return 0; 539 540 // Now create a new block that ends with the break statement. 541 Block = createBlock(false); 542 Block->setTerminator(B); 543 544 // If there is no target for the break, then we are looking at an incomplete 545 // AST. This means that the CFG cannot be constructed. 546 if (BreakTargetBlock) 547 AddSuccessor(Block, BreakTargetBlock); 548 else 549 badCFG = true; 550 551 552 return Block; 553} 554 555static bool CanThrow(Expr *E) { 556 QualType Ty = E->getType(); 557 if (Ty->isFunctionPointerType()) 558 Ty = Ty->getAs<PointerType>()->getPointeeType(); 559 else if (Ty->isBlockPointerType()) 560 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 561 562 const FunctionType *FT = Ty->getAs<FunctionType>(); 563 if (FT) { 564 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 565 if (Proto->hasEmptyExceptionSpec()) 566 return false; 567 } 568 return true; 569} 570 571CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 572 // If this is a call to a no-return function, this stops the block here. 573 bool NoReturn = false; 574 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 575 NoReturn = true; 576 } 577 578 bool AddEHEdge = false; 579 580 // Languages without exceptions are assumed to not throw. 581 if (Context->getLangOptions().Exceptions) { 582 if (AddEHEdges) 583 AddEHEdge = true; 584 } 585 586 if (FunctionDecl *FD = C->getDirectCallee()) { 587 if (FD->hasAttr<NoReturnAttr>()) 588 NoReturn = true; 589 if (FD->hasAttr<NoThrowAttr>()) 590 AddEHEdge = false; 591 } 592 593 if (!CanThrow(C->getCallee())) 594 AddEHEdge = false; 595 596 if (!NoReturn && !AddEHEdge) 597 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 598 599 if (Block) { 600 Succ = Block; 601 if (!FinishBlock(Block)) 602 return 0; 603 } 604 605 Block = createBlock(!NoReturn); 606 AppendStmt(Block, C, asc); 607 608 if (NoReturn) { 609 // Wire this to the exit block directly. 610 AddSuccessor(Block, &cfg->getExit()); 611 } 612 if (AddEHEdge) { 613 // Add exceptional edges. 614 if (TryTerminatedBlock) 615 AddSuccessor(Block, TryTerminatedBlock); 616 else 617 AddSuccessor(Block, &cfg->getExit()); 618 } 619 620 return VisitChildren(C); 621} 622 623CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 624 AddStmtChoice asc) { 625 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 626 AppendStmt(ConfluenceBlock, C, asc); 627 if (!FinishBlock(ConfluenceBlock)) 628 return 0; 629 630 Succ = ConfluenceBlock; 631 Block = NULL; 632 CFGBlock* LHSBlock = addStmt(C->getLHS()); 633 if (!FinishBlock(LHSBlock)) 634 return 0; 635 636 Succ = ConfluenceBlock; 637 Block = NULL; 638 CFGBlock* RHSBlock = addStmt(C->getRHS()); 639 if (!FinishBlock(RHSBlock)) 640 return 0; 641 642 Block = createBlock(false); 643 // See if this is a known constant. 644 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 645 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 646 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 647 Block->setTerminator(C); 648 return addStmt(C->getCond()); 649} 650 651 652CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 653 EndScope(C); 654 655 CFGBlock* LastBlock = Block; 656 657 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 658 I != E; ++I ) { 659 LastBlock = addStmt(*I); 660 661 if (badCFG) 662 return NULL; 663 } 664 665 LastBlock = StartScope(C, LastBlock); 666 667 return LastBlock; 668} 669 670CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 671 AddStmtChoice asc) { 672 // Create the confluence block that will "merge" the results of the ternary 673 // expression. 674 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 675 AppendStmt(ConfluenceBlock, C, asc); 676 if (!FinishBlock(ConfluenceBlock)) 677 return 0; 678 679 // Create a block for the LHS expression if there is an LHS expression. A 680 // GCC extension allows LHS to be NULL, causing the condition to be the 681 // value that is returned instead. 682 // e.g: x ?: y is shorthand for: x ? x : y; 683 Succ = ConfluenceBlock; 684 Block = NULL; 685 CFGBlock* LHSBlock = NULL; 686 if (C->getLHS()) { 687 LHSBlock = addStmt(C->getLHS()); 688 if (!FinishBlock(LHSBlock)) 689 return 0; 690 Block = NULL; 691 } 692 693 // Create the block for the RHS expression. 694 Succ = ConfluenceBlock; 695 CFGBlock* RHSBlock = addStmt(C->getRHS()); 696 if (!FinishBlock(RHSBlock)) 697 return 0; 698 699 // Create the block that will contain the condition. 700 Block = createBlock(false); 701 702 // See if this is a known constant. 703 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 704 if (LHSBlock) { 705 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 706 } else { 707 if (KnownVal.isFalse()) { 708 // If we know the condition is false, add NULL as the successor for 709 // the block containing the condition. In this case, the confluence 710 // block will have just one predecessor. 711 AddSuccessor(Block, 0); 712 assert(ConfluenceBlock->pred_size() == 1); 713 } else { 714 // If we have no LHS expression, add the ConfluenceBlock as a direct 715 // successor for the block containing the condition. Moreover, we need to 716 // reverse the order of the predecessors in the ConfluenceBlock because 717 // the RHSBlock will have been added to the succcessors already, and we 718 // want the first predecessor to the the block containing the expression 719 // for the case when the ternary expression evaluates to true. 720 AddSuccessor(Block, ConfluenceBlock); 721 assert(ConfluenceBlock->pred_size() == 2); 722 std::reverse(ConfluenceBlock->pred_begin(), 723 ConfluenceBlock->pred_end()); 724 } 725 } 726 727 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 728 Block->setTerminator(C); 729 return addStmt(C->getCond()); 730} 731 732CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 733 autoCreateBlock(); 734 735 if (DS->isSingleDecl()) { 736 AppendStmt(Block, DS); 737 return VisitDeclSubExpr(DS->getSingleDecl()); 738 } 739 740 CFGBlock *B = 0; 741 742 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 743 typedef llvm::SmallVector<Decl*,10> BufTy; 744 BufTy Buf(DS->decl_begin(), DS->decl_end()); 745 746 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 747 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 748 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 749 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 750 751 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 752 // automatically freed with the CFG. 753 DeclGroupRef DG(*I); 754 Decl *D = *I; 755 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 756 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 757 758 // Append the fake DeclStmt to block. 759 AppendStmt(Block, DSNew); 760 B = VisitDeclSubExpr(D); 761 } 762 763 return B; 764} 765 766/// VisitDeclSubExpr - Utility method to add block-level expressions for 767/// initializers in Decls. 768CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 769 assert(Block); 770 771 VarDecl *VD = dyn_cast<VarDecl>(D); 772 773 if (!VD) 774 return Block; 775 776 Expr *Init = VD->getInit(); 777 778 if (Init) { 779 AddStmtChoice::Kind k = 780 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 781 : AddStmtChoice::NotAlwaysAdd; 782 Visit(Init, AddStmtChoice(k)); 783 } 784 785 // If the type of VD is a VLA, then we must process its size expressions. 786 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 787 VA = FindVA(VA->getElementType().getTypePtr())) 788 Block = addStmt(VA->getSizeExpr()); 789 790 return Block; 791} 792 793CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 794 // We may see an if statement in the middle of a basic block, or it may be the 795 // first statement we are processing. In either case, we create a new basic 796 // block. First, we create the blocks for the then...else statements, and 797 // then we create the block containing the if statement. If we were in the 798 // middle of a block, we stop processing that block. That block is then the 799 // implicit successor for the "then" and "else" clauses. 800 801 // The block we were proccessing is now finished. Make it the successor 802 // block. 803 if (Block) { 804 Succ = Block; 805 if (!FinishBlock(Block)) 806 return 0; 807 } 808 809 // Process the false branch. 810 CFGBlock* ElseBlock = Succ; 811 812 if (Stmt* Else = I->getElse()) { 813 SaveAndRestore<CFGBlock*> sv(Succ); 814 815 // NULL out Block so that the recursive call to Visit will 816 // create a new basic block. 817 Block = NULL; 818 ElseBlock = addStmt(Else); 819 820 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 821 ElseBlock = sv.get(); 822 else if (Block) { 823 if (!FinishBlock(ElseBlock)) 824 return 0; 825 } 826 } 827 828 // Process the true branch. 829 CFGBlock* ThenBlock; 830 { 831 Stmt* Then = I->getThen(); 832 assert(Then); 833 SaveAndRestore<CFGBlock*> sv(Succ); 834 Block = NULL; 835 ThenBlock = addStmt(Then); 836 837 if (!ThenBlock) { 838 // We can reach here if the "then" body has all NullStmts. 839 // Create an empty block so we can distinguish between true and false 840 // branches in path-sensitive analyses. 841 ThenBlock = createBlock(false); 842 AddSuccessor(ThenBlock, sv.get()); 843 } else if (Block) { 844 if (!FinishBlock(ThenBlock)) 845 return 0; 846 } 847 } 848 849 // Now create a new block containing the if statement. 850 Block = createBlock(false); 851 852 // Set the terminator of the new block to the If statement. 853 Block->setTerminator(I); 854 855 // See if this is a known constant. 856 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 857 858 // Now add the successors. 859 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 860 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 861 862 // Add the condition as the last statement in the new block. This may create 863 // new blocks as the condition may contain control-flow. Any newly created 864 // blocks will be pointed to be "Block". 865 Block = addStmt(I->getCond()); 866 867 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 868 // and the condition variable initialization to the CFG. 869 if (VarDecl *VD = I->getConditionVariable()) { 870 if (Expr *Init = VD->getInit()) { 871 autoCreateBlock(); 872 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 873 addStmt(Init); 874 } 875 } 876 877 return Block; 878} 879 880 881CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 882 // If we were in the middle of a block we stop processing that block. 883 // 884 // NOTE: If a "return" appears in the middle of a block, this means that the 885 // code afterwards is DEAD (unreachable). We still keep a basic block 886 // for that code; a simple "mark-and-sweep" from the entry block will be 887 // able to report such dead blocks. 888 if (Block) 889 FinishBlock(Block); 890 891 // Create the new block. 892 Block = createBlock(false); 893 894 // The Exit block is the only successor. 895 AddSuccessor(Block, &cfg->getExit()); 896 897 // Add the return statement to the block. This may create new blocks if R 898 // contains control-flow (short-circuit operations). 899 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 900} 901 902CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 903 // Get the block of the labeled statement. Add it to our map. 904 addStmt(L->getSubStmt()); 905 CFGBlock* LabelBlock = Block; 906 907 if (!LabelBlock) // This can happen when the body is empty, i.e. 908 LabelBlock = createBlock(); // scopes that only contains NullStmts. 909 910 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 911 LabelMap[ L ] = LabelBlock; 912 913 // Labels partition blocks, so this is the end of the basic block we were 914 // processing (L is the block's label). Because this is label (and we have 915 // already processed the substatement) there is no extra control-flow to worry 916 // about. 917 LabelBlock->setLabel(L); 918 if (!FinishBlock(LabelBlock)) 919 return 0; 920 921 // We set Block to NULL to allow lazy creation of a new block (if necessary); 922 Block = NULL; 923 924 // This block is now the implicit successor of other blocks. 925 Succ = LabelBlock; 926 927 return LabelBlock; 928} 929 930CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 931 // Goto is a control-flow statement. Thus we stop processing the current 932 // block and create a new one. 933 if (Block) 934 FinishBlock(Block); 935 936 Block = createBlock(false); 937 Block->setTerminator(G); 938 939 // If we already know the mapping to the label block add the successor now. 940 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 941 942 if (I == LabelMap.end()) 943 // We will need to backpatch this block later. 944 BackpatchBlocks.push_back(Block); 945 else 946 AddSuccessor(Block, I->second); 947 948 return Block; 949} 950 951CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 952 CFGBlock* LoopSuccessor = NULL; 953 954 // "for" is a control-flow statement. Thus we stop processing the current 955 // block. 956 if (Block) { 957 if (!FinishBlock(Block)) 958 return 0; 959 LoopSuccessor = Block; 960 } else 961 LoopSuccessor = Succ; 962 963 // Because of short-circuit evaluation, the condition of the loop can span 964 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 965 // evaluate the condition. 966 CFGBlock* ExitConditionBlock = createBlock(false); 967 CFGBlock* EntryConditionBlock = ExitConditionBlock; 968 969 // Set the terminator for the "exit" condition block. 970 ExitConditionBlock->setTerminator(F); 971 972 // Now add the actual condition to the condition block. Because the condition 973 // itself may contain control-flow, new blocks may be created. 974 if (Stmt* C = F->getCond()) { 975 Block = ExitConditionBlock; 976 EntryConditionBlock = addStmt(C); 977 assert(Block == EntryConditionBlock); 978 979 // If this block contains a condition variable, add both the condition 980 // variable and initializer to the CFG. 981 if (VarDecl *VD = F->getConditionVariable()) { 982 if (Expr *Init = VD->getInit()) { 983 autoCreateBlock(); 984 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 985 EntryConditionBlock = addStmt(Init); 986 assert(Block == EntryConditionBlock); 987 } 988 } 989 990 if (Block) { 991 if (!FinishBlock(EntryConditionBlock)) 992 return 0; 993 } 994 } 995 996 // The condition block is the implicit successor for the loop body as well as 997 // any code above the loop. 998 Succ = EntryConditionBlock; 999 1000 // See if this is a known constant. 1001 TryResult KnownVal(true); 1002 1003 if (F->getCond()) 1004 KnownVal = TryEvaluateBool(F->getCond()); 1005 1006 // Now create the loop body. 1007 { 1008 assert(F->getBody()); 1009 1010 // Save the current values for Block, Succ, and continue and break targets 1011 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1012 save_continue(ContinueTargetBlock), 1013 save_break(BreakTargetBlock); 1014 1015 // Create a new block to contain the (bottom) of the loop body. 1016 Block = NULL; 1017 1018 if (Stmt* I = F->getInc()) { 1019 // Generate increment code in its own basic block. This is the target of 1020 // continue statements. 1021 Succ = addStmt(I); 1022 } else { 1023 // No increment code. Create a special, empty, block that is used as the 1024 // target block for "looping back" to the start of the loop. 1025 assert(Succ == EntryConditionBlock); 1026 Succ = createBlock(); 1027 } 1028 1029 // Finish up the increment (or empty) block if it hasn't been already. 1030 if (Block) { 1031 assert(Block == Succ); 1032 if (!FinishBlock(Block)) 1033 return 0; 1034 Block = 0; 1035 } 1036 1037 ContinueTargetBlock = Succ; 1038 1039 // The starting block for the loop increment is the block that should 1040 // represent the 'loop target' for looping back to the start of the loop. 1041 ContinueTargetBlock->setLoopTarget(F); 1042 1043 // All breaks should go to the code following the loop. 1044 BreakTargetBlock = LoopSuccessor; 1045 1046 // Now populate the body block, and in the process create new blocks as we 1047 // walk the body of the loop. 1048 CFGBlock* BodyBlock = addStmt(F->getBody()); 1049 1050 if (!BodyBlock) 1051 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1052 else if (Block && !FinishBlock(BodyBlock)) 1053 return 0; 1054 1055 // This new body block is a successor to our "exit" condition block. 1056 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1057 } 1058 1059 // Link up the condition block with the code that follows the loop. (the 1060 // false branch). 1061 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1062 1063 // If the loop contains initialization, create a new block for those 1064 // statements. This block can also contain statements that precede the loop. 1065 if (Stmt* I = F->getInit()) { 1066 Block = createBlock(); 1067 return addStmt(I); 1068 } else { 1069 // There is no loop initialization. We are thus basically a while loop. 1070 // NULL out Block to force lazy block construction. 1071 Block = NULL; 1072 Succ = EntryConditionBlock; 1073 return EntryConditionBlock; 1074 } 1075} 1076 1077CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1078 // Objective-C fast enumeration 'for' statements: 1079 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1080 // 1081 // for ( Type newVariable in collection_expression ) { statements } 1082 // 1083 // becomes: 1084 // 1085 // prologue: 1086 // 1. collection_expression 1087 // T. jump to loop_entry 1088 // loop_entry: 1089 // 1. side-effects of element expression 1090 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1091 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1092 // TB: 1093 // statements 1094 // T. jump to loop_entry 1095 // FB: 1096 // what comes after 1097 // 1098 // and 1099 // 1100 // Type existingItem; 1101 // for ( existingItem in expression ) { statements } 1102 // 1103 // becomes: 1104 // 1105 // the same with newVariable replaced with existingItem; the binding works 1106 // the same except that for one ObjCForCollectionStmt::getElement() returns 1107 // a DeclStmt and the other returns a DeclRefExpr. 1108 // 1109 1110 CFGBlock* LoopSuccessor = 0; 1111 1112 if (Block) { 1113 if (!FinishBlock(Block)) 1114 return 0; 1115 LoopSuccessor = Block; 1116 Block = 0; 1117 } else 1118 LoopSuccessor = Succ; 1119 1120 // Build the condition blocks. 1121 CFGBlock* ExitConditionBlock = createBlock(false); 1122 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1123 1124 // Set the terminator for the "exit" condition block. 1125 ExitConditionBlock->setTerminator(S); 1126 1127 // The last statement in the block should be the ObjCForCollectionStmt, which 1128 // performs the actual binding to 'element' and determines if there are any 1129 // more items in the collection. 1130 AppendStmt(ExitConditionBlock, S); 1131 Block = ExitConditionBlock; 1132 1133 // Walk the 'element' expression to see if there are any side-effects. We 1134 // generate new blocks as necesary. We DON'T add the statement by default to 1135 // the CFG unless it contains control-flow. 1136 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1137 if (Block) { 1138 if (!FinishBlock(EntryConditionBlock)) 1139 return 0; 1140 Block = 0; 1141 } 1142 1143 // The condition block is the implicit successor for the loop body as well as 1144 // any code above the loop. 1145 Succ = EntryConditionBlock; 1146 1147 // Now create the true branch. 1148 { 1149 // Save the current values for Succ, continue and break targets. 1150 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1151 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1152 1153 BreakTargetBlock = LoopSuccessor; 1154 ContinueTargetBlock = EntryConditionBlock; 1155 1156 CFGBlock* BodyBlock = addStmt(S->getBody()); 1157 1158 if (!BodyBlock) 1159 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1160 else if (Block) { 1161 if (!FinishBlock(BodyBlock)) 1162 return 0; 1163 } 1164 1165 // This new body block is a successor to our "exit" condition block. 1166 AddSuccessor(ExitConditionBlock, BodyBlock); 1167 } 1168 1169 // Link up the condition block with the code that follows the loop. 1170 // (the false branch). 1171 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1172 1173 // Now create a prologue block to contain the collection expression. 1174 Block = createBlock(); 1175 return addStmt(S->getCollection()); 1176} 1177 1178CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1179 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1180 1181 // Inline the body. 1182 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1183 1184 // The sync body starts its own basic block. This makes it a little easier 1185 // for diagnostic clients. 1186 if (SyncBlock) { 1187 if (!FinishBlock(SyncBlock)) 1188 return 0; 1189 1190 Block = 0; 1191 } 1192 1193 Succ = SyncBlock; 1194 1195 // Inline the sync expression. 1196 return addStmt(S->getSynchExpr()); 1197} 1198 1199CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1200 // FIXME 1201 return NYS(); 1202} 1203 1204CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1205 CFGBlock* LoopSuccessor = NULL; 1206 1207 // "while" is a control-flow statement. Thus we stop processing the current 1208 // block. 1209 if (Block) { 1210 if (!FinishBlock(Block)) 1211 return 0; 1212 LoopSuccessor = Block; 1213 } else 1214 LoopSuccessor = Succ; 1215 1216 // Because of short-circuit evaluation, the condition of the loop can span 1217 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1218 // evaluate the condition. 1219 CFGBlock* ExitConditionBlock = createBlock(false); 1220 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1221 1222 // Set the terminator for the "exit" condition block. 1223 ExitConditionBlock->setTerminator(W); 1224 1225 // Now add the actual condition to the condition block. Because the condition 1226 // itself may contain control-flow, new blocks may be created. Thus we update 1227 // "Succ" after adding the condition. 1228 if (Stmt* C = W->getCond()) { 1229 Block = ExitConditionBlock; 1230 EntryConditionBlock = addStmt(C); 1231 assert(Block == EntryConditionBlock); 1232 1233 // If this block contains a condition variable, add both the condition 1234 // variable and initializer to the CFG. 1235 if (VarDecl *VD = W->getConditionVariable()) { 1236 if (Expr *Init = VD->getInit()) { 1237 autoCreateBlock(); 1238 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1239 EntryConditionBlock = addStmt(Init); 1240 assert(Block == EntryConditionBlock); 1241 } 1242 } 1243 1244 if (Block) { 1245 if (!FinishBlock(EntryConditionBlock)) 1246 return 0; 1247 } 1248 } 1249 1250 // The condition block is the implicit successor for the loop body as well as 1251 // any code above the loop. 1252 Succ = EntryConditionBlock; 1253 1254 // See if this is a known constant. 1255 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1256 1257 // Process the loop body. 1258 { 1259 assert(W->getBody()); 1260 1261 // Save the current values for Block, Succ, and continue and break targets 1262 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1263 save_continue(ContinueTargetBlock), 1264 save_break(BreakTargetBlock); 1265 1266 // Create an empty block to represent the transition block for looping back 1267 // to the head of the loop. 1268 Block = 0; 1269 assert(Succ == EntryConditionBlock); 1270 Succ = createBlock(); 1271 Succ->setLoopTarget(W); 1272 ContinueTargetBlock = Succ; 1273 1274 // All breaks should go to the code following the loop. 1275 BreakTargetBlock = LoopSuccessor; 1276 1277 // NULL out Block to force lazy instantiation of blocks for the body. 1278 Block = NULL; 1279 1280 // Create the body. The returned block is the entry to the loop body. 1281 CFGBlock* BodyBlock = addStmt(W->getBody()); 1282 1283 if (!BodyBlock) 1284 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1285 else if (Block) { 1286 if (!FinishBlock(BodyBlock)) 1287 return 0; 1288 } 1289 1290 // Add the loop body entry as a successor to the condition. 1291 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1292 } 1293 1294 // Link up the condition block with the code that follows the loop. (the 1295 // false branch). 1296 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1297 1298 // There can be no more statements in the condition block since we loop back 1299 // to this block. NULL out Block to force lazy creation of another block. 1300 Block = NULL; 1301 1302 // Return the condition block, which is the dominating block for the loop. 1303 Succ = EntryConditionBlock; 1304 return EntryConditionBlock; 1305} 1306 1307 1308CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1309 // FIXME: For now we pretend that @catch and the code it contains does not 1310 // exit. 1311 return Block; 1312} 1313 1314CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1315 // FIXME: This isn't complete. We basically treat @throw like a return 1316 // statement. 1317 1318 // If we were in the middle of a block we stop processing that block. 1319 if (Block && !FinishBlock(Block)) 1320 return 0; 1321 1322 // Create the new block. 1323 Block = createBlock(false); 1324 1325 // The Exit block is the only successor. 1326 AddSuccessor(Block, &cfg->getExit()); 1327 1328 // Add the statement to the block. This may create new blocks if S contains 1329 // control-flow (short-circuit operations). 1330 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1331} 1332 1333CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1334 // If we were in the middle of a block we stop processing that block. 1335 if (Block && !FinishBlock(Block)) 1336 return 0; 1337 1338 // Create the new block. 1339 Block = createBlock(false); 1340 1341 if (TryTerminatedBlock) 1342 // The current try statement is the only successor. 1343 AddSuccessor(Block, TryTerminatedBlock); 1344 else 1345 // otherwise the Exit block is the only successor. 1346 AddSuccessor(Block, &cfg->getExit()); 1347 1348 // Add the statement to the block. This may create new blocks if S contains 1349 // control-flow (short-circuit operations). 1350 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1351} 1352 1353CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1354 CFGBlock* LoopSuccessor = NULL; 1355 1356 // "do...while" is a control-flow statement. Thus we stop processing the 1357 // current block. 1358 if (Block) { 1359 if (!FinishBlock(Block)) 1360 return 0; 1361 LoopSuccessor = Block; 1362 } else 1363 LoopSuccessor = Succ; 1364 1365 // Because of short-circuit evaluation, the condition of the loop can span 1366 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1367 // evaluate the condition. 1368 CFGBlock* ExitConditionBlock = createBlock(false); 1369 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1370 1371 // Set the terminator for the "exit" condition block. 1372 ExitConditionBlock->setTerminator(D); 1373 1374 // Now add the actual condition to the condition block. Because the condition 1375 // itself may contain control-flow, new blocks may be created. 1376 if (Stmt* C = D->getCond()) { 1377 Block = ExitConditionBlock; 1378 EntryConditionBlock = addStmt(C); 1379 if (Block) { 1380 if (!FinishBlock(EntryConditionBlock)) 1381 return 0; 1382 } 1383 } 1384 1385 // The condition block is the implicit successor for the loop body. 1386 Succ = EntryConditionBlock; 1387 1388 // See if this is a known constant. 1389 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1390 1391 // Process the loop body. 1392 CFGBlock* BodyBlock = NULL; 1393 { 1394 assert(D->getBody()); 1395 1396 // Save the current values for Block, Succ, and continue and break targets 1397 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1398 save_continue(ContinueTargetBlock), 1399 save_break(BreakTargetBlock); 1400 1401 // All continues within this loop should go to the condition block 1402 ContinueTargetBlock = EntryConditionBlock; 1403 1404 // All breaks should go to the code following the loop. 1405 BreakTargetBlock = LoopSuccessor; 1406 1407 // NULL out Block to force lazy instantiation of blocks for the body. 1408 Block = NULL; 1409 1410 // Create the body. The returned block is the entry to the loop body. 1411 BodyBlock = addStmt(D->getBody()); 1412 1413 if (!BodyBlock) 1414 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1415 else if (Block) { 1416 if (!FinishBlock(BodyBlock)) 1417 return 0; 1418 } 1419 1420 // Add an intermediate block between the BodyBlock and the 1421 // ExitConditionBlock to represent the "loop back" transition. Create an 1422 // empty block to represent the transition block for looping back to the 1423 // head of the loop. 1424 // FIXME: Can we do this more efficiently without adding another block? 1425 Block = NULL; 1426 Succ = BodyBlock; 1427 CFGBlock *LoopBackBlock = createBlock(); 1428 LoopBackBlock->setLoopTarget(D); 1429 1430 // Add the loop body entry as a successor to the condition. 1431 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : LoopBackBlock); 1432 } 1433 1434 // Link up the condition block with the code that follows the loop. 1435 // (the false branch). 1436 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1437 1438 // There can be no more statements in the body block(s) since we loop back to 1439 // the body. NULL out Block to force lazy creation of another block. 1440 Block = NULL; 1441 1442 // Return the loop body, which is the dominating block for the loop. 1443 Succ = BodyBlock; 1444 return BodyBlock; 1445} 1446 1447CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1448 // "continue" is a control-flow statement. Thus we stop processing the 1449 // current block. 1450 if (Block && !FinishBlock(Block)) 1451 return 0; 1452 1453 // Now create a new block that ends with the continue statement. 1454 Block = createBlock(false); 1455 Block->setTerminator(C); 1456 1457 // If there is no target for the continue, then we are looking at an 1458 // incomplete AST. This means the CFG cannot be constructed. 1459 if (ContinueTargetBlock) 1460 AddSuccessor(Block, ContinueTargetBlock); 1461 else 1462 badCFG = true; 1463 1464 return Block; 1465} 1466 1467CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1468 AddStmtChoice asc) { 1469 1470 if (asc.alwaysAdd()) { 1471 autoCreateBlock(); 1472 AppendStmt(Block, E); 1473 } 1474 1475 // VLA types have expressions that must be evaluated. 1476 if (E->isArgumentType()) { 1477 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1478 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1479 addStmt(VA->getSizeExpr()); 1480 } 1481 1482 return Block; 1483} 1484 1485/// VisitStmtExpr - Utility method to handle (nested) statement 1486/// expressions (a GCC extension). 1487CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1488 if (asc.alwaysAdd()) { 1489 autoCreateBlock(); 1490 AppendStmt(Block, SE); 1491 } 1492 return VisitCompoundStmt(SE->getSubStmt()); 1493} 1494 1495CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1496 // "switch" is a control-flow statement. Thus we stop processing the current 1497 // block. 1498 CFGBlock* SwitchSuccessor = NULL; 1499 1500 if (Block) { 1501 if (!FinishBlock(Block)) 1502 return 0; 1503 SwitchSuccessor = Block; 1504 } else SwitchSuccessor = Succ; 1505 1506 // Save the current "switch" context. 1507 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1508 save_break(BreakTargetBlock), 1509 save_default(DefaultCaseBlock); 1510 1511 // Set the "default" case to be the block after the switch statement. If the 1512 // switch statement contains a "default:", this value will be overwritten with 1513 // the block for that code. 1514 DefaultCaseBlock = SwitchSuccessor; 1515 1516 // Create a new block that will contain the switch statement. 1517 SwitchTerminatedBlock = createBlock(false); 1518 1519 // Now process the switch body. The code after the switch is the implicit 1520 // successor. 1521 Succ = SwitchSuccessor; 1522 BreakTargetBlock = SwitchSuccessor; 1523 1524 // When visiting the body, the case statements should automatically get linked 1525 // up to the switch. We also don't keep a pointer to the body, since all 1526 // control-flow from the switch goes to case/default statements. 1527 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1528 Block = NULL; 1529 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1530 if (Block) { 1531 if (!FinishBlock(BodyBlock)) 1532 return 0; 1533 } 1534 1535 // If we have no "default:" case, the default transition is to the code 1536 // following the switch body. 1537 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1538 1539 // Add the terminator and condition in the switch block. 1540 SwitchTerminatedBlock->setTerminator(Terminator); 1541 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1542 Block = SwitchTerminatedBlock; 1543 Block = addStmt(Terminator->getCond()); 1544 1545 // Finally, if the SwitchStmt contains a condition variable, add both the 1546 // SwitchStmt and the condition variable initialization to the CFG. 1547 if (VarDecl *VD = Terminator->getConditionVariable()) { 1548 if (Expr *Init = VD->getInit()) { 1549 autoCreateBlock(); 1550 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1551 addStmt(Init); 1552 } 1553 } 1554 1555 return Block; 1556} 1557 1558CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1559 // CaseStmts are essentially labels, so they are the first statement in a 1560 // block. 1561 1562 if (CS->getSubStmt()) 1563 addStmt(CS->getSubStmt()); 1564 1565 CFGBlock* CaseBlock = Block; 1566 if (!CaseBlock) 1567 CaseBlock = createBlock(); 1568 1569 // Cases statements partition blocks, so this is the top of the basic block we 1570 // were processing (the "case XXX:" is the label). 1571 CaseBlock->setLabel(CS); 1572 1573 if (!FinishBlock(CaseBlock)) 1574 return 0; 1575 1576 // Add this block to the list of successors for the block with the switch 1577 // statement. 1578 assert(SwitchTerminatedBlock); 1579 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1580 1581 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1582 Block = NULL; 1583 1584 // This block is now the implicit successor of other blocks. 1585 Succ = CaseBlock; 1586 1587 return CaseBlock; 1588} 1589 1590CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1591 if (Terminator->getSubStmt()) 1592 addStmt(Terminator->getSubStmt()); 1593 1594 DefaultCaseBlock = Block; 1595 1596 if (!DefaultCaseBlock) 1597 DefaultCaseBlock = createBlock(); 1598 1599 // Default statements partition blocks, so this is the top of the basic block 1600 // we were processing (the "default:" is the label). 1601 DefaultCaseBlock->setLabel(Terminator); 1602 1603 if (!FinishBlock(DefaultCaseBlock)) 1604 return 0; 1605 1606 // Unlike case statements, we don't add the default block to the successors 1607 // for the switch statement immediately. This is done when we finish 1608 // processing the switch statement. This allows for the default case 1609 // (including a fall-through to the code after the switch statement) to always 1610 // be the last successor of a switch-terminated block. 1611 1612 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1613 Block = NULL; 1614 1615 // This block is now the implicit successor of other blocks. 1616 Succ = DefaultCaseBlock; 1617 1618 return DefaultCaseBlock; 1619} 1620 1621CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1622 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1623 // current block. 1624 CFGBlock* TrySuccessor = NULL; 1625 1626 if (Block) { 1627 if (!FinishBlock(Block)) 1628 return 0; 1629 TrySuccessor = Block; 1630 } else TrySuccessor = Succ; 1631 1632 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1633 1634 // Create a new block that will contain the try statement. 1635 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1636 // Add the terminator in the try block. 1637 NewTryTerminatedBlock->setTerminator(Terminator); 1638 1639 bool HasCatchAll = false; 1640 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1641 // The code after the try is the implicit successor. 1642 Succ = TrySuccessor; 1643 CXXCatchStmt *CS = Terminator->getHandler(h); 1644 if (CS->getExceptionDecl() == 0) { 1645 HasCatchAll = true; 1646 } 1647 Block = NULL; 1648 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1649 if (CatchBlock == 0) 1650 return 0; 1651 // Add this block to the list of successors for the block with the try 1652 // statement. 1653 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1654 } 1655 if (!HasCatchAll) { 1656 if (PrevTryTerminatedBlock) 1657 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1658 else 1659 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1660 } 1661 1662 // The code after the try is the implicit successor. 1663 Succ = TrySuccessor; 1664 1665 // Save the current "try" context. 1666 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1667 TryTerminatedBlock = NewTryTerminatedBlock; 1668 1669 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1670 Block = NULL; 1671 Block = addStmt(Terminator->getTryBlock()); 1672 return Block; 1673} 1674 1675CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1676 // CXXCatchStmt are treated like labels, so they are the first statement in a 1677 // block. 1678 1679 if (CS->getHandlerBlock()) 1680 addStmt(CS->getHandlerBlock()); 1681 1682 CFGBlock* CatchBlock = Block; 1683 if (!CatchBlock) 1684 CatchBlock = createBlock(); 1685 1686 CatchBlock->setLabel(CS); 1687 1688 if (!FinishBlock(CatchBlock)) 1689 return 0; 1690 1691 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1692 Block = NULL; 1693 1694 return CatchBlock; 1695} 1696 1697CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1698 // Lazily create the indirect-goto dispatch block if there isn't one already. 1699 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1700 1701 if (!IBlock) { 1702 IBlock = createBlock(false); 1703 cfg->setIndirectGotoBlock(IBlock); 1704 } 1705 1706 // IndirectGoto is a control-flow statement. Thus we stop processing the 1707 // current block and create a new one. 1708 if (Block && !FinishBlock(Block)) 1709 return 0; 1710 1711 Block = createBlock(false); 1712 Block->setTerminator(I); 1713 AddSuccessor(Block, IBlock); 1714 return addStmt(I->getTarget()); 1715} 1716 1717} // end anonymous namespace 1718 1719/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1720/// no successors or predecessors. If this is the first block created in the 1721/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1722CFGBlock* CFG::createBlock() { 1723 bool first_block = begin() == end(); 1724 1725 // Create the block. 1726 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1727 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1728 Blocks.push_back(Mem, BlkBVC); 1729 1730 // If this is the first block, set it as the Entry and Exit. 1731 if (first_block) 1732 Entry = Exit = &back(); 1733 1734 // Return the block. 1735 return &back(); 1736} 1737 1738/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1739/// CFG is returned to the caller. 1740CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1741 bool AddEHEdges, bool AddScopes) { 1742 CFGBuilder Builder; 1743 return Builder.buildCFG(D, Statement, C, AddEHEdges, AddScopes); 1744} 1745 1746//===----------------------------------------------------------------------===// 1747// CFG: Queries for BlkExprs. 1748//===----------------------------------------------------------------------===// 1749 1750namespace { 1751 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1752} 1753 1754static void FindSubExprAssignments(Stmt *S, 1755 llvm::SmallPtrSet<Expr*,50>& Set) { 1756 if (!S) 1757 return; 1758 1759 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1760 Stmt *child = *I; 1761 if (!child) 1762 continue; 1763 1764 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1765 if (B->isAssignmentOp()) Set.insert(B); 1766 1767 FindSubExprAssignments(child, Set); 1768 } 1769} 1770 1771static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1772 BlkExprMapTy* M = new BlkExprMapTy(); 1773 1774 // Look for assignments that are used as subexpressions. These are the only 1775 // assignments that we want to *possibly* register as a block-level 1776 // expression. Basically, if an assignment occurs both in a subexpression and 1777 // at the block-level, it is a block-level expression. 1778 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1779 1780 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1781 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1782 FindSubExprAssignments(*BI, SubExprAssignments); 1783 1784 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1785 1786 // Iterate over the statements again on identify the Expr* and Stmt* at the 1787 // block-level that are block-level expressions. 1788 1789 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1790 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1791 1792 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1793 // Assignment expressions that are not nested within another 1794 // expression are really "statements" whose value is never used by 1795 // another expression. 1796 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1797 continue; 1798 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1799 // Special handling for statement expressions. The last statement in 1800 // the statement expression is also a block-level expr. 1801 const CompoundStmt* C = Terminator->getSubStmt(); 1802 if (!C->body_empty()) { 1803 unsigned x = M->size(); 1804 (*M)[C->body_back()] = x; 1805 } 1806 } 1807 1808 unsigned x = M->size(); 1809 (*M)[Exp] = x; 1810 } 1811 1812 // Look at terminators. The condition is a block-level expression. 1813 1814 Stmt* S = (*I)->getTerminatorCondition(); 1815 1816 if (S && M->find(S) == M->end()) { 1817 unsigned x = M->size(); 1818 (*M)[S] = x; 1819 } 1820 } 1821 1822 return M; 1823} 1824 1825CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1826 assert(S != NULL); 1827 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1828 1829 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1830 BlkExprMapTy::iterator I = M->find(S); 1831 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1832} 1833 1834unsigned CFG::getNumBlkExprs() { 1835 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1836 return M->size(); 1837 else { 1838 // We assume callers interested in the number of BlkExprs will want 1839 // the map constructed if it doesn't already exist. 1840 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1841 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1842 } 1843} 1844 1845//===----------------------------------------------------------------------===// 1846// Cleanup: CFG dstor. 1847//===----------------------------------------------------------------------===// 1848 1849CFG::~CFG() { 1850 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1851} 1852 1853//===----------------------------------------------------------------------===// 1854// CFG pretty printing 1855//===----------------------------------------------------------------------===// 1856 1857namespace { 1858 1859class StmtPrinterHelper : public PrinterHelper { 1860 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1861 StmtMapTy StmtMap; 1862 signed CurrentBlock; 1863 unsigned CurrentStmt; 1864 const LangOptions &LangOpts; 1865public: 1866 1867 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1868 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1869 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1870 unsigned j = 1; 1871 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1872 BI != BEnd; ++BI, ++j ) 1873 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1874 } 1875 } 1876 1877 virtual ~StmtPrinterHelper() {} 1878 1879 const LangOptions &getLangOpts() const { return LangOpts; } 1880 void setBlockID(signed i) { CurrentBlock = i; } 1881 void setStmtID(unsigned i) { CurrentStmt = i; } 1882 1883 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1884 1885 StmtMapTy::iterator I = StmtMap.find(Terminator); 1886 1887 if (I == StmtMap.end()) 1888 return false; 1889 1890 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 1891 && I->second.second == CurrentStmt) { 1892 return false; 1893 } 1894 1895 OS << "[B" << I->second.first << "." << I->second.second << "]"; 1896 return true; 1897 } 1898}; 1899} // end anonymous namespace 1900 1901 1902namespace { 1903class CFGBlockTerminatorPrint 1904 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 1905 1906 llvm::raw_ostream& OS; 1907 StmtPrinterHelper* Helper; 1908 PrintingPolicy Policy; 1909public: 1910 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 1911 const PrintingPolicy &Policy) 1912 : OS(os), Helper(helper), Policy(Policy) {} 1913 1914 void VisitIfStmt(IfStmt* I) { 1915 OS << "if "; 1916 I->getCond()->printPretty(OS,Helper,Policy); 1917 } 1918 1919 // Default case. 1920 void VisitStmt(Stmt* Terminator) { 1921 Terminator->printPretty(OS, Helper, Policy); 1922 } 1923 1924 void VisitForStmt(ForStmt* F) { 1925 OS << "for (" ; 1926 if (F->getInit()) 1927 OS << "..."; 1928 OS << "; "; 1929 if (Stmt* C = F->getCond()) 1930 C->printPretty(OS, Helper, Policy); 1931 OS << "; "; 1932 if (F->getInc()) 1933 OS << "..."; 1934 OS << ")"; 1935 } 1936 1937 void VisitWhileStmt(WhileStmt* W) { 1938 OS << "while " ; 1939 if (Stmt* C = W->getCond()) 1940 C->printPretty(OS, Helper, Policy); 1941 } 1942 1943 void VisitDoStmt(DoStmt* D) { 1944 OS << "do ... while "; 1945 if (Stmt* C = D->getCond()) 1946 C->printPretty(OS, Helper, Policy); 1947 } 1948 1949 void VisitSwitchStmt(SwitchStmt* Terminator) { 1950 OS << "switch "; 1951 Terminator->getCond()->printPretty(OS, Helper, Policy); 1952 } 1953 1954 void VisitCXXTryStmt(CXXTryStmt* CS) { 1955 OS << "try ..."; 1956 } 1957 1958 void VisitConditionalOperator(ConditionalOperator* C) { 1959 C->getCond()->printPretty(OS, Helper, Policy); 1960 OS << " ? ... : ..."; 1961 } 1962 1963 void VisitChooseExpr(ChooseExpr* C) { 1964 OS << "__builtin_choose_expr( "; 1965 C->getCond()->printPretty(OS, Helper, Policy); 1966 OS << " )"; 1967 } 1968 1969 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1970 OS << "goto *"; 1971 I->getTarget()->printPretty(OS, Helper, Policy); 1972 } 1973 1974 void VisitBinaryOperator(BinaryOperator* B) { 1975 if (!B->isLogicalOp()) { 1976 VisitExpr(B); 1977 return; 1978 } 1979 1980 B->getLHS()->printPretty(OS, Helper, Policy); 1981 1982 switch (B->getOpcode()) { 1983 case BinaryOperator::LOr: 1984 OS << " || ..."; 1985 return; 1986 case BinaryOperator::LAnd: 1987 OS << " && ..."; 1988 return; 1989 default: 1990 assert(false && "Invalid logical operator."); 1991 } 1992 } 1993 1994 void VisitExpr(Expr* E) { 1995 E->printPretty(OS, Helper, Policy); 1996 } 1997}; 1998} // end anonymous namespace 1999 2000 2001static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2002 const CFGElement &E) { 2003 Stmt *Terminator = E; 2004 2005 if (E.asStartScope()) { 2006 OS << "start scope\n"; 2007 return; 2008 } 2009 if (E.asEndScope()) { 2010 OS << "end scope\n"; 2011 return; 2012 } 2013 2014 if (Helper) { 2015 // special printing for statement-expressions. 2016 if (StmtExpr* SE = dyn_cast<StmtExpr>(Terminator)) { 2017 CompoundStmt* Sub = SE->getSubStmt(); 2018 2019 if (Sub->child_begin() != Sub->child_end()) { 2020 OS << "({ ... ; "; 2021 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2022 OS << " })\n"; 2023 return; 2024 } 2025 } 2026 2027 // special printing for comma expressions. 2028 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Terminator)) { 2029 if (B->getOpcode() == BinaryOperator::Comma) { 2030 OS << "... , "; 2031 Helper->handledStmt(B->getRHS(),OS); 2032 OS << '\n'; 2033 return; 2034 } 2035 } 2036 } 2037 2038 Terminator->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2039 2040 // Expressions need a newline. 2041 if (isa<Expr>(Terminator)) OS << '\n'; 2042} 2043 2044static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2045 const CFGBlock& B, 2046 StmtPrinterHelper* Helper, bool print_edges) { 2047 2048 if (Helper) Helper->setBlockID(B.getBlockID()); 2049 2050 // Print the header. 2051 OS << "\n [ B" << B.getBlockID(); 2052 2053 if (&B == &cfg->getEntry()) 2054 OS << " (ENTRY) ]\n"; 2055 else if (&B == &cfg->getExit()) 2056 OS << " (EXIT) ]\n"; 2057 else if (&B == cfg->getIndirectGotoBlock()) 2058 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2059 else 2060 OS << " ]\n"; 2061 2062 // Print the label of this block. 2063 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2064 2065 if (print_edges) 2066 OS << " "; 2067 2068 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2069 OS << L->getName(); 2070 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2071 OS << "case "; 2072 C->getLHS()->printPretty(OS, Helper, 2073 PrintingPolicy(Helper->getLangOpts())); 2074 if (C->getRHS()) { 2075 OS << " ... "; 2076 C->getRHS()->printPretty(OS, Helper, 2077 PrintingPolicy(Helper->getLangOpts())); 2078 } 2079 } else if (isa<DefaultStmt>(Label)) 2080 OS << "default"; 2081 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2082 OS << "catch ("; 2083 if (CS->getExceptionDecl()) 2084 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2085 0); 2086 else 2087 OS << "..."; 2088 OS << ")"; 2089 2090 } else 2091 assert(false && "Invalid label statement in CFGBlock."); 2092 2093 OS << ":\n"; 2094 } 2095 2096 // Iterate through the statements in the block and print them. 2097 unsigned j = 1; 2098 2099 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2100 I != E ; ++I, ++j ) { 2101 2102 // Print the statement # in the basic block and the statement itself. 2103 if (print_edges) 2104 OS << " "; 2105 2106 OS << llvm::format("%3d", j) << ": "; 2107 2108 if (Helper) 2109 Helper->setStmtID(j); 2110 2111 print_stmt(OS,Helper,*I); 2112 } 2113 2114 // Print the terminator of this block. 2115 if (B.getTerminator()) { 2116 if (print_edges) 2117 OS << " "; 2118 2119 OS << " T: "; 2120 2121 if (Helper) Helper->setBlockID(-1); 2122 2123 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2124 PrintingPolicy(Helper->getLangOpts())); 2125 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2126 OS << '\n'; 2127 } 2128 2129 if (print_edges) { 2130 // Print the predecessors of this block. 2131 OS << " Predecessors (" << B.pred_size() << "):"; 2132 unsigned i = 0; 2133 2134 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2135 I != E; ++I, ++i) { 2136 2137 if (i == 8 || (i-8) == 0) 2138 OS << "\n "; 2139 2140 OS << " B" << (*I)->getBlockID(); 2141 } 2142 2143 OS << '\n'; 2144 2145 // Print the successors of this block. 2146 OS << " Successors (" << B.succ_size() << "):"; 2147 i = 0; 2148 2149 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2150 I != E; ++I, ++i) { 2151 2152 if (i == 8 || (i-8) % 10 == 0) 2153 OS << "\n "; 2154 2155 if (*I) 2156 OS << " B" << (*I)->getBlockID(); 2157 else 2158 OS << " NULL"; 2159 } 2160 2161 OS << '\n'; 2162 } 2163} 2164 2165 2166/// dump - A simple pretty printer of a CFG that outputs to stderr. 2167void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2168 2169/// print - A simple pretty printer of a CFG that outputs to an ostream. 2170void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2171 StmtPrinterHelper Helper(this, LO); 2172 2173 // Print the entry block. 2174 print_block(OS, this, getEntry(), &Helper, true); 2175 2176 // Iterate through the CFGBlocks and print them one by one. 2177 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2178 // Skip the entry block, because we already printed it. 2179 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2180 continue; 2181 2182 print_block(OS, this, **I, &Helper, true); 2183 } 2184 2185 // Print the exit block. 2186 print_block(OS, this, getExit(), &Helper, true); 2187 OS.flush(); 2188} 2189 2190/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2191void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2192 print(llvm::errs(), cfg, LO); 2193} 2194 2195/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2196/// Generally this will only be called from CFG::print. 2197void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2198 const LangOptions &LO) const { 2199 StmtPrinterHelper Helper(cfg, LO); 2200 print_block(OS, cfg, *this, &Helper, true); 2201} 2202 2203/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2204void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2205 const LangOptions &LO) const { 2206 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2207 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2208} 2209 2210Stmt* CFGBlock::getTerminatorCondition() { 2211 2212 if (!Terminator) 2213 return NULL; 2214 2215 Expr* E = NULL; 2216 2217 switch (Terminator->getStmtClass()) { 2218 default: 2219 break; 2220 2221 case Stmt::ForStmtClass: 2222 E = cast<ForStmt>(Terminator)->getCond(); 2223 break; 2224 2225 case Stmt::WhileStmtClass: 2226 E = cast<WhileStmt>(Terminator)->getCond(); 2227 break; 2228 2229 case Stmt::DoStmtClass: 2230 E = cast<DoStmt>(Terminator)->getCond(); 2231 break; 2232 2233 case Stmt::IfStmtClass: 2234 E = cast<IfStmt>(Terminator)->getCond(); 2235 break; 2236 2237 case Stmt::ChooseExprClass: 2238 E = cast<ChooseExpr>(Terminator)->getCond(); 2239 break; 2240 2241 case Stmt::IndirectGotoStmtClass: 2242 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2243 break; 2244 2245 case Stmt::SwitchStmtClass: 2246 E = cast<SwitchStmt>(Terminator)->getCond(); 2247 break; 2248 2249 case Stmt::ConditionalOperatorClass: 2250 E = cast<ConditionalOperator>(Terminator)->getCond(); 2251 break; 2252 2253 case Stmt::BinaryOperatorClass: // '&&' and '||' 2254 E = cast<BinaryOperator>(Terminator)->getLHS(); 2255 break; 2256 2257 case Stmt::ObjCForCollectionStmtClass: 2258 return Terminator; 2259 } 2260 2261 return E ? E->IgnoreParens() : NULL; 2262} 2263 2264bool CFGBlock::hasBinaryBranchTerminator() const { 2265 2266 if (!Terminator) 2267 return false; 2268 2269 Expr* E = NULL; 2270 2271 switch (Terminator->getStmtClass()) { 2272 default: 2273 return false; 2274 2275 case Stmt::ForStmtClass: 2276 case Stmt::WhileStmtClass: 2277 case Stmt::DoStmtClass: 2278 case Stmt::IfStmtClass: 2279 case Stmt::ChooseExprClass: 2280 case Stmt::ConditionalOperatorClass: 2281 case Stmt::BinaryOperatorClass: 2282 return true; 2283 } 2284 2285 return E ? E->IgnoreParens() : NULL; 2286} 2287 2288 2289//===----------------------------------------------------------------------===// 2290// CFG Graphviz Visualization 2291//===----------------------------------------------------------------------===// 2292 2293 2294#ifndef NDEBUG 2295static StmtPrinterHelper* GraphHelper; 2296#endif 2297 2298void CFG::viewCFG(const LangOptions &LO) const { 2299#ifndef NDEBUG 2300 StmtPrinterHelper H(this, LO); 2301 GraphHelper = &H; 2302 llvm::ViewGraph(this,"CFG"); 2303 GraphHelper = NULL; 2304#endif 2305} 2306 2307namespace llvm { 2308template<> 2309struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2310 2311 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2312 2313 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2314 2315#ifndef NDEBUG 2316 std::string OutSStr; 2317 llvm::raw_string_ostream Out(OutSStr); 2318 print_block(Out,Graph, *Node, GraphHelper, false); 2319 std::string& OutStr = Out.str(); 2320 2321 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2322 2323 // Process string output to make it nicer... 2324 for (unsigned i = 0; i != OutStr.length(); ++i) 2325 if (OutStr[i] == '\n') { // Left justify 2326 OutStr[i] = '\\'; 2327 OutStr.insert(OutStr.begin()+i+1, 'l'); 2328 } 2329 2330 return OutStr; 2331#else 2332 return ""; 2333#endif 2334 } 2335}; 2336} // end namespace llvm 2337