CFG.cpp revision c8cc79dc43fdf92c099deb0603499a16f84f0dc4
1//===--- CFG.cpp - Classes for representing and building CFGs----*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the CFG and CFGBuilder classes for representing and 11// building Control-Flow Graphs (CFGs) from ASTs. 12// 13//===----------------------------------------------------------------------===// 14 15#include "clang/Analysis/Support/SaveAndRestore.h" 16#include "clang/Analysis/CFG.h" 17#include "clang/AST/DeclCXX.h" 18#include "clang/AST/StmtVisitor.h" 19#include "clang/AST/PrettyPrinter.h" 20#include "llvm/Support/GraphWriter.h" 21#include "llvm/Support/Allocator.h" 22#include "llvm/Support/Format.h" 23#include "llvm/ADT/DenseMap.h" 24#include "llvm/ADT/SmallPtrSet.h" 25#include "llvm/ADT/OwningPtr.h" 26 27using namespace clang; 28 29namespace { 30 31static SourceLocation GetEndLoc(Decl* D) { 32 if (VarDecl* VD = dyn_cast<VarDecl>(D)) 33 if (Expr* Ex = VD->getInit()) 34 return Ex->getSourceRange().getEnd(); 35 36 return D->getLocation(); 37} 38 39class AddStmtChoice { 40public: 41 enum Kind { NotAlwaysAdd = 0, 42 AlwaysAdd = 1, 43 AsLValueNotAlwaysAdd = 2, 44 AlwaysAddAsLValue = 3 }; 45 46 AddStmtChoice(Kind kind) : k(kind) {} 47 48 bool alwaysAdd() const { return (unsigned)k & 0x1; } 49 bool asLValue() const { return k >= AsLValueNotAlwaysAdd; } 50 51private: 52 Kind k; 53}; 54 55/// CFGBuilder - This class implements CFG construction from an AST. 56/// The builder is stateful: an instance of the builder should be used to only 57/// construct a single CFG. 58/// 59/// Example usage: 60/// 61/// CFGBuilder builder; 62/// CFG* cfg = builder.BuildAST(stmt1); 63/// 64/// CFG construction is done via a recursive walk of an AST. We actually parse 65/// the AST in reverse order so that the successor of a basic block is 66/// constructed prior to its predecessor. This allows us to nicely capture 67/// implicit fall-throughs without extra basic blocks. 68/// 69class CFGBuilder { 70 ASTContext *Context; 71 llvm::OwningPtr<CFG> cfg; 72 73 CFGBlock* Block; 74 CFGBlock* Succ; 75 CFGBlock* ContinueTargetBlock; 76 CFGBlock* BreakTargetBlock; 77 CFGBlock* SwitchTerminatedBlock; 78 CFGBlock* DefaultCaseBlock; 79 CFGBlock* TryTerminatedBlock; 80 81 // LabelMap records the mapping from Label expressions to their blocks. 82 typedef llvm::DenseMap<LabelStmt*,CFGBlock*> LabelMapTy; 83 LabelMapTy LabelMap; 84 85 // A list of blocks that end with a "goto" that must be backpatched to their 86 // resolved targets upon completion of CFG construction. 87 typedef std::vector<CFGBlock*> BackpatchBlocksTy; 88 BackpatchBlocksTy BackpatchBlocks; 89 90 // A list of labels whose address has been taken (for indirect gotos). 91 typedef llvm::SmallPtrSet<LabelStmt*,5> LabelSetTy; 92 LabelSetTy AddressTakenLabels; 93 94public: 95 explicit CFGBuilder() : cfg(new CFG()), // crew a new CFG 96 Block(NULL), Succ(NULL), 97 ContinueTargetBlock(NULL), BreakTargetBlock(NULL), 98 SwitchTerminatedBlock(NULL), DefaultCaseBlock(NULL), 99 TryTerminatedBlock(NULL) {} 100 101 // buildCFG - Used by external clients to construct the CFG. 102 CFG* buildCFG(const Decl *D, Stmt *Statement, ASTContext *C, 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 *VisitCXXCatchStmt(CXXCatchStmt *S); 112 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 113 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 114 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 115 CFGBlock *VisitCaseStmt(CaseStmt *C); 116 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 117 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 118 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, AddStmtChoice asc); 119 CFGBlock *VisitContinueStmt(ContinueStmt *C); 120 CFGBlock *VisitDeclStmt(DeclStmt *DS); 121 CFGBlock *VisitDeclSubExpr(Decl* D); 122 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 123 CFGBlock *VisitDoStmt(DoStmt *D); 124 CFGBlock *VisitForStmt(ForStmt *F); 125 CFGBlock *VisitGotoStmt(GotoStmt* G); 126 CFGBlock *VisitIfStmt(IfStmt *I); 127 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 128 CFGBlock *VisitLabelStmt(LabelStmt *L); 129 CFGBlock *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc); 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::MemberExprClass: 408 return VisitMemberExpr(cast<MemberExpr>(S), asc); 409 410 case Stmt::ObjCAtCatchStmtClass: 411 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 412 413 case Stmt::ObjCAtSynchronizedStmtClass: 414 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 415 416 case Stmt::ObjCAtThrowStmtClass: 417 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 418 419 case Stmt::ObjCAtTryStmtClass: 420 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 421 422 case Stmt::ObjCForCollectionStmtClass: 423 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 424 425 case Stmt::ParenExprClass: 426 S = cast<ParenExpr>(S)->getSubExpr(); 427 goto tryAgain; 428 429 case Stmt::NullStmtClass: 430 return Block; 431 432 case Stmt::ReturnStmtClass: 433 return VisitReturnStmt(cast<ReturnStmt>(S)); 434 435 case Stmt::SizeOfAlignOfExprClass: 436 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 437 438 case Stmt::StmtExprClass: 439 return VisitStmtExpr(cast<StmtExpr>(S), asc); 440 441 case Stmt::SwitchStmtClass: 442 return VisitSwitchStmt(cast<SwitchStmt>(S)); 443 444 case Stmt::WhileStmtClass: 445 return VisitWhileStmt(cast<WhileStmt>(S)); 446 } 447} 448 449CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 450 if (asc.alwaysAdd()) { 451 autoCreateBlock(); 452 AppendStmt(Block, S, asc); 453 } 454 455 return VisitChildren(S); 456} 457 458/// VisitChildren - Visit the children of a Stmt. 459CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 460 CFGBlock *B = Block; 461 for (Stmt::child_iterator I = Terminator->child_begin(), 462 E = Terminator->child_end(); I != E; ++I) { 463 if (*I) B = Visit(*I); 464 } 465 return B; 466} 467 468CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 469 AddStmtChoice asc) { 470 AddressTakenLabels.insert(A->getLabel()); 471 472 if (asc.alwaysAdd()) { 473 autoCreateBlock(); 474 AppendStmt(Block, A, asc); 475 } 476 477 return Block; 478} 479 480CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 481 AddStmtChoice asc) { 482 if (B->isLogicalOp()) { // && or || 483 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 484 AppendStmt(ConfluenceBlock, B, asc); 485 486 if (!FinishBlock(ConfluenceBlock)) 487 return 0; 488 489 // create the block evaluating the LHS 490 CFGBlock* LHSBlock = createBlock(false); 491 LHSBlock->setTerminator(B); 492 493 // create the block evaluating the RHS 494 Succ = ConfluenceBlock; 495 Block = NULL; 496 CFGBlock* RHSBlock = addStmt(B->getRHS()); 497 if (!FinishBlock(RHSBlock)) 498 return 0; 499 500 // See if this is a known constant. 501 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 502 if (KnownVal.isKnown() && (B->getOpcode() == BinaryOperator::LOr)) 503 KnownVal.negate(); 504 505 // Now link the LHSBlock with RHSBlock. 506 if (B->getOpcode() == BinaryOperator::LOr) { 507 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 508 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 509 } else { 510 assert(B->getOpcode() == BinaryOperator::LAnd); 511 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 512 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 513 } 514 515 // Generate the blocks for evaluating the LHS. 516 Block = LHSBlock; 517 return addStmt(B->getLHS()); 518 } 519 else if (B->getOpcode() == BinaryOperator::Comma) { // , 520 autoCreateBlock(); 521 AppendStmt(Block, B, asc); 522 addStmt(B->getRHS()); 523 return addStmt(B->getLHS()); 524 } 525 526 return VisitStmt(B, asc); 527} 528 529CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 530 if (asc.alwaysAdd()) { 531 autoCreateBlock(); 532 AppendStmt(Block, E, asc); 533 } 534 return Block; 535} 536 537CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 538 // "break" is a control-flow statement. Thus we stop processing the current 539 // block. 540 if (Block && !FinishBlock(Block)) 541 return 0; 542 543 // Now create a new block that ends with the break statement. 544 Block = createBlock(false); 545 Block->setTerminator(B); 546 547 // If there is no target for the break, then we are looking at an incomplete 548 // AST. This means that the CFG cannot be constructed. 549 if (BreakTargetBlock) 550 AddSuccessor(Block, BreakTargetBlock); 551 else 552 badCFG = true; 553 554 555 return Block; 556} 557 558static bool CanThrow(Expr *E) { 559 QualType Ty = E->getType(); 560 if (Ty->isFunctionPointerType()) 561 Ty = Ty->getAs<PointerType>()->getPointeeType(); 562 else if (Ty->isBlockPointerType()) 563 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 564 565 const FunctionType *FT = Ty->getAs<FunctionType>(); 566 if (FT) { 567 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 568 if (Proto->hasEmptyExceptionSpec()) 569 return false; 570 } 571 return true; 572} 573 574CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 575 // If this is a call to a no-return function, this stops the block here. 576 bool NoReturn = false; 577 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 578 NoReturn = true; 579 } 580 581 bool AddEHEdge = false; 582 583 // Languages without exceptions are assumed to not throw. 584 if (Context->getLangOptions().Exceptions) { 585 if (AddEHEdges) 586 AddEHEdge = true; 587 } 588 589 if (FunctionDecl *FD = C->getDirectCallee()) { 590 if (FD->hasAttr<NoReturnAttr>()) 591 NoReturn = true; 592 if (FD->hasAttr<NoThrowAttr>()) 593 AddEHEdge = false; 594 } 595 596 if (!CanThrow(C->getCallee())) 597 AddEHEdge = false; 598 599 if (!NoReturn && !AddEHEdge) 600 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 601 602 if (Block) { 603 Succ = Block; 604 if (!FinishBlock(Block)) 605 return 0; 606 } 607 608 Block = createBlock(!NoReturn); 609 AppendStmt(Block, C, asc); 610 611 if (NoReturn) { 612 // Wire this to the exit block directly. 613 AddSuccessor(Block, &cfg->getExit()); 614 } 615 if (AddEHEdge) { 616 // Add exceptional edges. 617 if (TryTerminatedBlock) 618 AddSuccessor(Block, TryTerminatedBlock); 619 else 620 AddSuccessor(Block, &cfg->getExit()); 621 } 622 623 return VisitChildren(C); 624} 625 626CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 627 AddStmtChoice asc) { 628 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 629 AppendStmt(ConfluenceBlock, C, asc); 630 if (!FinishBlock(ConfluenceBlock)) 631 return 0; 632 633 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 634 : AddStmtChoice::AlwaysAdd; 635 636 Succ = ConfluenceBlock; 637 Block = NULL; 638 CFGBlock* LHSBlock = addStmt(C->getLHS(), asc); 639 if (!FinishBlock(LHSBlock)) 640 return 0; 641 642 Succ = ConfluenceBlock; 643 Block = NULL; 644 CFGBlock* RHSBlock = addStmt(C->getRHS(), asc); 645 if (!FinishBlock(RHSBlock)) 646 return 0; 647 648 Block = createBlock(false); 649 // See if this is a known constant. 650 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 651 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 652 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 653 Block->setTerminator(C); 654 return addStmt(C->getCond()); 655} 656 657 658CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 659 EndScope(C); 660 661 CFGBlock* LastBlock = Block; 662 663 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 664 I != E; ++I ) { 665 LastBlock = addStmt(*I); 666 667 if (badCFG) 668 return NULL; 669 } 670 671 LastBlock = StartScope(C, LastBlock); 672 673 return LastBlock; 674} 675 676CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 677 AddStmtChoice asc) { 678 // Create the confluence block that will "merge" the results of the ternary 679 // expression. 680 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 681 AppendStmt(ConfluenceBlock, C, asc); 682 if (!FinishBlock(ConfluenceBlock)) 683 return 0; 684 685 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 686 : AddStmtChoice::AlwaysAdd; 687 688 // Create a block for the LHS expression if there is an LHS expression. A 689 // GCC extension allows LHS to be NULL, causing the condition to be the 690 // value that is returned instead. 691 // e.g: x ?: y is shorthand for: x ? x : y; 692 Succ = ConfluenceBlock; 693 Block = NULL; 694 CFGBlock* LHSBlock = NULL; 695 if (C->getLHS()) { 696 LHSBlock = addStmt(C->getLHS(), asc); 697 if (!FinishBlock(LHSBlock)) 698 return 0; 699 Block = NULL; 700 } 701 702 // Create the block for the RHS expression. 703 Succ = ConfluenceBlock; 704 CFGBlock* RHSBlock = addStmt(C->getRHS(), asc); 705 if (!FinishBlock(RHSBlock)) 706 return 0; 707 708 // Create the block that will contain the condition. 709 Block = createBlock(false); 710 711 // See if this is a known constant. 712 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 713 if (LHSBlock) { 714 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 715 } else { 716 if (KnownVal.isFalse()) { 717 // If we know the condition is false, add NULL as the successor for 718 // the block containing the condition. In this case, the confluence 719 // block will have just one predecessor. 720 AddSuccessor(Block, 0); 721 assert(ConfluenceBlock->pred_size() == 1); 722 } else { 723 // If we have no LHS expression, add the ConfluenceBlock as a direct 724 // successor for the block containing the condition. Moreover, we need to 725 // reverse the order of the predecessors in the ConfluenceBlock because 726 // the RHSBlock will have been added to the succcessors already, and we 727 // want the first predecessor to the the block containing the expression 728 // for the case when the ternary expression evaluates to true. 729 AddSuccessor(Block, ConfluenceBlock); 730 assert(ConfluenceBlock->pred_size() == 2); 731 std::reverse(ConfluenceBlock->pred_begin(), 732 ConfluenceBlock->pred_end()); 733 } 734 } 735 736 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 737 Block->setTerminator(C); 738 return addStmt(C->getCond()); 739} 740 741CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 742 autoCreateBlock(); 743 744 if (DS->isSingleDecl()) { 745 AppendStmt(Block, DS); 746 return VisitDeclSubExpr(DS->getSingleDecl()); 747 } 748 749 CFGBlock *B = 0; 750 751 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 752 typedef llvm::SmallVector<Decl*,10> BufTy; 753 BufTy Buf(DS->decl_begin(), DS->decl_end()); 754 755 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 756 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 757 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 758 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 759 760 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 761 // automatically freed with the CFG. 762 DeclGroupRef DG(*I); 763 Decl *D = *I; 764 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 765 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 766 767 // Append the fake DeclStmt to block. 768 AppendStmt(Block, DSNew); 769 B = VisitDeclSubExpr(D); 770 } 771 772 return B; 773} 774 775/// VisitDeclSubExpr - Utility method to add block-level expressions for 776/// initializers in Decls. 777CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 778 assert(Block); 779 780 VarDecl *VD = dyn_cast<VarDecl>(D); 781 782 if (!VD) 783 return Block; 784 785 Expr *Init = VD->getInit(); 786 787 if (Init) { 788 AddStmtChoice::Kind k = 789 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 790 : AddStmtChoice::NotAlwaysAdd; 791 Visit(Init, AddStmtChoice(k)); 792 } 793 794 // If the type of VD is a VLA, then we must process its size expressions. 795 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 796 VA = FindVA(VA->getElementType().getTypePtr())) 797 Block = addStmt(VA->getSizeExpr()); 798 799 return Block; 800} 801 802CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 803 // We may see an if statement in the middle of a basic block, or it may be the 804 // first statement we are processing. In either case, we create a new basic 805 // block. First, we create the blocks for the then...else statements, and 806 // then we create the block containing the if statement. If we were in the 807 // middle of a block, we stop processing that block. That block is then the 808 // implicit successor for the "then" and "else" clauses. 809 810 // The block we were proccessing is now finished. Make it the successor 811 // block. 812 if (Block) { 813 Succ = Block; 814 if (!FinishBlock(Block)) 815 return 0; 816 } 817 818 // Process the false branch. 819 CFGBlock* ElseBlock = Succ; 820 821 if (Stmt* Else = I->getElse()) { 822 SaveAndRestore<CFGBlock*> sv(Succ); 823 824 // NULL out Block so that the recursive call to Visit will 825 // create a new basic block. 826 Block = NULL; 827 ElseBlock = addStmt(Else); 828 829 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 830 ElseBlock = sv.get(); 831 else if (Block) { 832 if (!FinishBlock(ElseBlock)) 833 return 0; 834 } 835 } 836 837 // Process the true branch. 838 CFGBlock* ThenBlock; 839 { 840 Stmt* Then = I->getThen(); 841 assert(Then); 842 SaveAndRestore<CFGBlock*> sv(Succ); 843 Block = NULL; 844 ThenBlock = addStmt(Then); 845 846 if (!ThenBlock) { 847 // We can reach here if the "then" body has all NullStmts. 848 // Create an empty block so we can distinguish between true and false 849 // branches in path-sensitive analyses. 850 ThenBlock = createBlock(false); 851 AddSuccessor(ThenBlock, sv.get()); 852 } else if (Block) { 853 if (!FinishBlock(ThenBlock)) 854 return 0; 855 } 856 } 857 858 // Now create a new block containing the if statement. 859 Block = createBlock(false); 860 861 // Set the terminator of the new block to the If statement. 862 Block->setTerminator(I); 863 864 // See if this is a known constant. 865 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 866 867 // Now add the successors. 868 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 869 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 870 871 // Add the condition as the last statement in the new block. This may create 872 // new blocks as the condition may contain control-flow. Any newly created 873 // blocks will be pointed to be "Block". 874 Block = addStmt(I->getCond()); 875 876 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 877 // and the condition variable initialization to the CFG. 878 if (VarDecl *VD = I->getConditionVariable()) { 879 if (Expr *Init = VD->getInit()) { 880 autoCreateBlock(); 881 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 882 addStmt(Init); 883 } 884 } 885 886 return Block; 887} 888 889 890CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 891 // If we were in the middle of a block we stop processing that block. 892 // 893 // NOTE: If a "return" appears in the middle of a block, this means that the 894 // code afterwards is DEAD (unreachable). We still keep a basic block 895 // for that code; a simple "mark-and-sweep" from the entry block will be 896 // able to report such dead blocks. 897 if (Block) 898 FinishBlock(Block); 899 900 // Create the new block. 901 Block = createBlock(false); 902 903 // The Exit block is the only successor. 904 AddSuccessor(Block, &cfg->getExit()); 905 906 // Add the return statement to the block. This may create new blocks if R 907 // contains control-flow (short-circuit operations). 908 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 909} 910 911CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 912 // Get the block of the labeled statement. Add it to our map. 913 addStmt(L->getSubStmt()); 914 CFGBlock* LabelBlock = Block; 915 916 if (!LabelBlock) // This can happen when the body is empty, i.e. 917 LabelBlock = createBlock(); // scopes that only contains NullStmts. 918 919 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 920 LabelMap[ L ] = LabelBlock; 921 922 // Labels partition blocks, so this is the end of the basic block we were 923 // processing (L is the block's label). Because this is label (and we have 924 // already processed the substatement) there is no extra control-flow to worry 925 // about. 926 LabelBlock->setLabel(L); 927 if (!FinishBlock(LabelBlock)) 928 return 0; 929 930 // We set Block to NULL to allow lazy creation of a new block (if necessary); 931 Block = NULL; 932 933 // This block is now the implicit successor of other blocks. 934 Succ = LabelBlock; 935 936 return LabelBlock; 937} 938 939CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 940 // Goto is a control-flow statement. Thus we stop processing the current 941 // block and create a new one. 942 if (Block) 943 FinishBlock(Block); 944 945 Block = createBlock(false); 946 Block->setTerminator(G); 947 948 // If we already know the mapping to the label block add the successor now. 949 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 950 951 if (I == LabelMap.end()) 952 // We will need to backpatch this block later. 953 BackpatchBlocks.push_back(Block); 954 else 955 AddSuccessor(Block, I->second); 956 957 return Block; 958} 959 960CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 961 CFGBlock* LoopSuccessor = NULL; 962 963 // "for" is a control-flow statement. Thus we stop processing the current 964 // block. 965 if (Block) { 966 if (!FinishBlock(Block)) 967 return 0; 968 LoopSuccessor = Block; 969 } else 970 LoopSuccessor = Succ; 971 972 // Because of short-circuit evaluation, the condition of the loop can span 973 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 974 // evaluate the condition. 975 CFGBlock* ExitConditionBlock = createBlock(false); 976 CFGBlock* EntryConditionBlock = ExitConditionBlock; 977 978 // Set the terminator for the "exit" condition block. 979 ExitConditionBlock->setTerminator(F); 980 981 // Now add the actual condition to the condition block. Because the condition 982 // itself may contain control-flow, new blocks may be created. 983 if (Stmt* C = F->getCond()) { 984 Block = ExitConditionBlock; 985 EntryConditionBlock = addStmt(C); 986 assert(Block == EntryConditionBlock); 987 988 // If this block contains a condition variable, add both the condition 989 // variable and initializer to the CFG. 990 if (VarDecl *VD = F->getConditionVariable()) { 991 if (Expr *Init = VD->getInit()) { 992 autoCreateBlock(); 993 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 994 EntryConditionBlock = addStmt(Init); 995 assert(Block == EntryConditionBlock); 996 } 997 } 998 999 if (Block) { 1000 if (!FinishBlock(EntryConditionBlock)) 1001 return 0; 1002 } 1003 } 1004 1005 // The condition block is the implicit successor for the loop body as well as 1006 // any code above the loop. 1007 Succ = EntryConditionBlock; 1008 1009 // See if this is a known constant. 1010 TryResult KnownVal(true); 1011 1012 if (F->getCond()) 1013 KnownVal = TryEvaluateBool(F->getCond()); 1014 1015 // Now create the loop body. 1016 { 1017 assert(F->getBody()); 1018 1019 // Save the current values for Block, Succ, and continue and break targets 1020 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1021 save_continue(ContinueTargetBlock), 1022 save_break(BreakTargetBlock); 1023 1024 // Create a new block to contain the (bottom) of the loop body. 1025 Block = NULL; 1026 1027 if (Stmt* I = F->getInc()) { 1028 // Generate increment code in its own basic block. This is the target of 1029 // continue statements. 1030 Succ = addStmt(I); 1031 } else { 1032 // No increment code. Create a special, empty, block that is used as the 1033 // target block for "looping back" to the start of the loop. 1034 assert(Succ == EntryConditionBlock); 1035 Succ = createBlock(); 1036 } 1037 1038 // Finish up the increment (or empty) block if it hasn't been already. 1039 if (Block) { 1040 assert(Block == Succ); 1041 if (!FinishBlock(Block)) 1042 return 0; 1043 Block = 0; 1044 } 1045 1046 ContinueTargetBlock = Succ; 1047 1048 // The starting block for the loop increment is the block that should 1049 // represent the 'loop target' for looping back to the start of the loop. 1050 ContinueTargetBlock->setLoopTarget(F); 1051 1052 // All breaks should go to the code following the loop. 1053 BreakTargetBlock = LoopSuccessor; 1054 1055 // Now populate the body block, and in the process create new blocks as we 1056 // walk the body of the loop. 1057 CFGBlock* BodyBlock = addStmt(F->getBody()); 1058 1059 if (!BodyBlock) 1060 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1061 else if (Block && !FinishBlock(BodyBlock)) 1062 return 0; 1063 1064 // This new body block is a successor to our "exit" condition block. 1065 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1066 } 1067 1068 // Link up the condition block with the code that follows the loop. (the 1069 // false branch). 1070 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1071 1072 // If the loop contains initialization, create a new block for those 1073 // statements. This block can also contain statements that precede the loop. 1074 if (Stmt* I = F->getInit()) { 1075 Block = createBlock(); 1076 return addStmt(I); 1077 } else { 1078 // There is no loop initialization. We are thus basically a while loop. 1079 // NULL out Block to force lazy block construction. 1080 Block = NULL; 1081 Succ = EntryConditionBlock; 1082 return EntryConditionBlock; 1083 } 1084} 1085 1086CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) { 1087 if (asc.alwaysAdd()) { 1088 autoCreateBlock(); 1089 AppendStmt(Block, M, asc); 1090 } 1091 return Visit(M->getBase(), 1092 M->isArrow() ? AddStmtChoice::NotAlwaysAdd 1093 : AddStmtChoice::AsLValueNotAlwaysAdd); 1094} 1095 1096CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1097 // Objective-C fast enumeration 'for' statements: 1098 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1099 // 1100 // for ( Type newVariable in collection_expression ) { statements } 1101 // 1102 // becomes: 1103 // 1104 // prologue: 1105 // 1. collection_expression 1106 // T. jump to loop_entry 1107 // loop_entry: 1108 // 1. side-effects of element expression 1109 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1110 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1111 // TB: 1112 // statements 1113 // T. jump to loop_entry 1114 // FB: 1115 // what comes after 1116 // 1117 // and 1118 // 1119 // Type existingItem; 1120 // for ( existingItem in expression ) { statements } 1121 // 1122 // becomes: 1123 // 1124 // the same with newVariable replaced with existingItem; the binding works 1125 // the same except that for one ObjCForCollectionStmt::getElement() returns 1126 // a DeclStmt and the other returns a DeclRefExpr. 1127 // 1128 1129 CFGBlock* LoopSuccessor = 0; 1130 1131 if (Block) { 1132 if (!FinishBlock(Block)) 1133 return 0; 1134 LoopSuccessor = Block; 1135 Block = 0; 1136 } else 1137 LoopSuccessor = Succ; 1138 1139 // Build the condition blocks. 1140 CFGBlock* ExitConditionBlock = createBlock(false); 1141 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1142 1143 // Set the terminator for the "exit" condition block. 1144 ExitConditionBlock->setTerminator(S); 1145 1146 // The last statement in the block should be the ObjCForCollectionStmt, which 1147 // performs the actual binding to 'element' and determines if there are any 1148 // more items in the collection. 1149 AppendStmt(ExitConditionBlock, S); 1150 Block = ExitConditionBlock; 1151 1152 // Walk the 'element' expression to see if there are any side-effects. We 1153 // generate new blocks as necesary. We DON'T add the statement by default to 1154 // the CFG unless it contains control-flow. 1155 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1156 if (Block) { 1157 if (!FinishBlock(EntryConditionBlock)) 1158 return 0; 1159 Block = 0; 1160 } 1161 1162 // The condition block is the implicit successor for the loop body as well as 1163 // any code above the loop. 1164 Succ = EntryConditionBlock; 1165 1166 // Now create the true branch. 1167 { 1168 // Save the current values for Succ, continue and break targets. 1169 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1170 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1171 1172 BreakTargetBlock = LoopSuccessor; 1173 ContinueTargetBlock = EntryConditionBlock; 1174 1175 CFGBlock* BodyBlock = addStmt(S->getBody()); 1176 1177 if (!BodyBlock) 1178 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1179 else if (Block) { 1180 if (!FinishBlock(BodyBlock)) 1181 return 0; 1182 } 1183 1184 // This new body block is a successor to our "exit" condition block. 1185 AddSuccessor(ExitConditionBlock, BodyBlock); 1186 } 1187 1188 // Link up the condition block with the code that follows the loop. 1189 // (the false branch). 1190 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1191 1192 // Now create a prologue block to contain the collection expression. 1193 Block = createBlock(); 1194 return addStmt(S->getCollection()); 1195} 1196 1197CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1198 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1199 1200 // Inline the body. 1201 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1202 1203 // The sync body starts its own basic block. This makes it a little easier 1204 // for diagnostic clients. 1205 if (SyncBlock) { 1206 if (!FinishBlock(SyncBlock)) 1207 return 0; 1208 1209 Block = 0; 1210 } 1211 1212 Succ = SyncBlock; 1213 1214 // Inline the sync expression. 1215 return addStmt(S->getSynchExpr()); 1216} 1217 1218CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1219 // FIXME 1220 return NYS(); 1221} 1222 1223CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1224 CFGBlock* LoopSuccessor = NULL; 1225 1226 // "while" is a control-flow statement. Thus we stop processing the current 1227 // block. 1228 if (Block) { 1229 if (!FinishBlock(Block)) 1230 return 0; 1231 LoopSuccessor = Block; 1232 } else 1233 LoopSuccessor = Succ; 1234 1235 // Because of short-circuit evaluation, the condition of the loop can span 1236 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1237 // evaluate the condition. 1238 CFGBlock* ExitConditionBlock = createBlock(false); 1239 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1240 1241 // Set the terminator for the "exit" condition block. 1242 ExitConditionBlock->setTerminator(W); 1243 1244 // Now add the actual condition to the condition block. Because the condition 1245 // itself may contain control-flow, new blocks may be created. Thus we update 1246 // "Succ" after adding the condition. 1247 if (Stmt* C = W->getCond()) { 1248 Block = ExitConditionBlock; 1249 EntryConditionBlock = addStmt(C); 1250 assert(Block == EntryConditionBlock); 1251 1252 // If this block contains a condition variable, add both the condition 1253 // variable and initializer to the CFG. 1254 if (VarDecl *VD = W->getConditionVariable()) { 1255 if (Expr *Init = VD->getInit()) { 1256 autoCreateBlock(); 1257 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1258 EntryConditionBlock = addStmt(Init); 1259 assert(Block == EntryConditionBlock); 1260 } 1261 } 1262 1263 if (Block) { 1264 if (!FinishBlock(EntryConditionBlock)) 1265 return 0; 1266 } 1267 } 1268 1269 // The condition block is the implicit successor for the loop body as well as 1270 // any code above the loop. 1271 Succ = EntryConditionBlock; 1272 1273 // See if this is a known constant. 1274 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1275 1276 // Process the loop body. 1277 { 1278 assert(W->getBody()); 1279 1280 // Save the current values for Block, Succ, and continue and break targets 1281 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1282 save_continue(ContinueTargetBlock), 1283 save_break(BreakTargetBlock); 1284 1285 // Create an empty block to represent the transition block for looping back 1286 // to the head of the loop. 1287 Block = 0; 1288 assert(Succ == EntryConditionBlock); 1289 Succ = createBlock(); 1290 Succ->setLoopTarget(W); 1291 ContinueTargetBlock = Succ; 1292 1293 // All breaks should go to the code following the loop. 1294 BreakTargetBlock = LoopSuccessor; 1295 1296 // NULL out Block to force lazy instantiation of blocks for the body. 1297 Block = NULL; 1298 1299 // Create the body. The returned block is the entry to the loop body. 1300 CFGBlock* BodyBlock = addStmt(W->getBody()); 1301 1302 if (!BodyBlock) 1303 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1304 else if (Block) { 1305 if (!FinishBlock(BodyBlock)) 1306 return 0; 1307 } 1308 1309 // Add the loop body entry as a successor to the condition. 1310 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1311 } 1312 1313 // Link up the condition block with the code that follows the loop. (the 1314 // false branch). 1315 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1316 1317 // There can be no more statements in the condition block since we loop back 1318 // to this block. NULL out Block to force lazy creation of another block. 1319 Block = NULL; 1320 1321 // Return the condition block, which is the dominating block for the loop. 1322 Succ = EntryConditionBlock; 1323 return EntryConditionBlock; 1324} 1325 1326 1327CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1328 // FIXME: For now we pretend that @catch and the code it contains does not 1329 // exit. 1330 return Block; 1331} 1332 1333CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1334 // FIXME: This isn't complete. We basically treat @throw like a return 1335 // statement. 1336 1337 // If we were in the middle of a block we stop processing that block. 1338 if (Block && !FinishBlock(Block)) 1339 return 0; 1340 1341 // Create the new block. 1342 Block = createBlock(false); 1343 1344 // The Exit block is the only successor. 1345 AddSuccessor(Block, &cfg->getExit()); 1346 1347 // Add the statement to the block. This may create new blocks if S contains 1348 // control-flow (short-circuit operations). 1349 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1350} 1351 1352CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1353 // If we were in the middle of a block we stop processing that block. 1354 if (Block && !FinishBlock(Block)) 1355 return 0; 1356 1357 // Create the new block. 1358 Block = createBlock(false); 1359 1360 if (TryTerminatedBlock) 1361 // The current try statement is the only successor. 1362 AddSuccessor(Block, TryTerminatedBlock); 1363 else 1364 // otherwise the Exit block is the only successor. 1365 AddSuccessor(Block, &cfg->getExit()); 1366 1367 // Add the statement to the block. This may create new blocks if S contains 1368 // control-flow (short-circuit operations). 1369 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1370} 1371 1372CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1373 CFGBlock* LoopSuccessor = NULL; 1374 1375 // "do...while" is a control-flow statement. Thus we stop processing the 1376 // current block. 1377 if (Block) { 1378 if (!FinishBlock(Block)) 1379 return 0; 1380 LoopSuccessor = Block; 1381 } else 1382 LoopSuccessor = Succ; 1383 1384 // Because of short-circuit evaluation, the condition of the loop can span 1385 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1386 // evaluate the condition. 1387 CFGBlock* ExitConditionBlock = createBlock(false); 1388 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1389 1390 // Set the terminator for the "exit" condition block. 1391 ExitConditionBlock->setTerminator(D); 1392 1393 // Now add the actual condition to the condition block. Because the condition 1394 // itself may contain control-flow, new blocks may be created. 1395 if (Stmt* C = D->getCond()) { 1396 Block = ExitConditionBlock; 1397 EntryConditionBlock = addStmt(C); 1398 if (Block) { 1399 if (!FinishBlock(EntryConditionBlock)) 1400 return 0; 1401 } 1402 } 1403 1404 // The condition block is the implicit successor for the loop body. 1405 Succ = EntryConditionBlock; 1406 1407 // See if this is a known constant. 1408 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1409 1410 // Process the loop body. 1411 CFGBlock* BodyBlock = NULL; 1412 { 1413 assert(D->getBody()); 1414 1415 // Save the current values for Block, Succ, and continue and break targets 1416 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1417 save_continue(ContinueTargetBlock), 1418 save_break(BreakTargetBlock); 1419 1420 // All continues within this loop should go to the condition block 1421 ContinueTargetBlock = EntryConditionBlock; 1422 1423 // All breaks should go to the code following the loop. 1424 BreakTargetBlock = LoopSuccessor; 1425 1426 // NULL out Block to force lazy instantiation of blocks for the body. 1427 Block = NULL; 1428 1429 // Create the body. The returned block is the entry to the loop body. 1430 BodyBlock = addStmt(D->getBody()); 1431 1432 if (!BodyBlock) 1433 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1434 else if (Block) { 1435 if (!FinishBlock(BodyBlock)) 1436 return 0; 1437 } 1438 1439 // Add an intermediate block between the BodyBlock and the 1440 // ExitConditionBlock to represent the "loop back" transition. Create an 1441 // empty block to represent the transition block for looping back to the 1442 // head of the loop. 1443 // FIXME: Can we do this more efficiently without adding another block? 1444 Block = NULL; 1445 Succ = BodyBlock; 1446 CFGBlock *LoopBackBlock = createBlock(); 1447 LoopBackBlock->setLoopTarget(D); 1448 1449 // Add the loop body entry as a successor to the condition. 1450 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : LoopBackBlock); 1451 } 1452 1453 // Link up the condition block with the code that follows the loop. 1454 // (the false branch). 1455 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1456 1457 // There can be no more statements in the body block(s) since we loop back to 1458 // the body. NULL out Block to force lazy creation of another block. 1459 Block = NULL; 1460 1461 // Return the loop body, which is the dominating block for the loop. 1462 Succ = BodyBlock; 1463 return BodyBlock; 1464} 1465 1466CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1467 // "continue" is a control-flow statement. Thus we stop processing the 1468 // current block. 1469 if (Block && !FinishBlock(Block)) 1470 return 0; 1471 1472 // Now create a new block that ends with the continue statement. 1473 Block = createBlock(false); 1474 Block->setTerminator(C); 1475 1476 // If there is no target for the continue, then we are looking at an 1477 // incomplete AST. This means the CFG cannot be constructed. 1478 if (ContinueTargetBlock) 1479 AddSuccessor(Block, ContinueTargetBlock); 1480 else 1481 badCFG = true; 1482 1483 return Block; 1484} 1485 1486CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1487 AddStmtChoice asc) { 1488 1489 if (asc.alwaysAdd()) { 1490 autoCreateBlock(); 1491 AppendStmt(Block, E); 1492 } 1493 1494 // VLA types have expressions that must be evaluated. 1495 if (E->isArgumentType()) { 1496 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1497 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1498 addStmt(VA->getSizeExpr()); 1499 } 1500 1501 return Block; 1502} 1503 1504/// VisitStmtExpr - Utility method to handle (nested) statement 1505/// expressions (a GCC extension). 1506CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1507 if (asc.alwaysAdd()) { 1508 autoCreateBlock(); 1509 AppendStmt(Block, SE); 1510 } 1511 return VisitCompoundStmt(SE->getSubStmt()); 1512} 1513 1514CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1515 // "switch" is a control-flow statement. Thus we stop processing the current 1516 // block. 1517 CFGBlock* SwitchSuccessor = NULL; 1518 1519 if (Block) { 1520 if (!FinishBlock(Block)) 1521 return 0; 1522 SwitchSuccessor = Block; 1523 } else SwitchSuccessor = Succ; 1524 1525 // Save the current "switch" context. 1526 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1527 save_break(BreakTargetBlock), 1528 save_default(DefaultCaseBlock); 1529 1530 // Set the "default" case to be the block after the switch statement. If the 1531 // switch statement contains a "default:", this value will be overwritten with 1532 // the block for that code. 1533 DefaultCaseBlock = SwitchSuccessor; 1534 1535 // Create a new block that will contain the switch statement. 1536 SwitchTerminatedBlock = createBlock(false); 1537 1538 // Now process the switch body. The code after the switch is the implicit 1539 // successor. 1540 Succ = SwitchSuccessor; 1541 BreakTargetBlock = SwitchSuccessor; 1542 1543 // When visiting the body, the case statements should automatically get linked 1544 // up to the switch. We also don't keep a pointer to the body, since all 1545 // control-flow from the switch goes to case/default statements. 1546 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1547 Block = NULL; 1548 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1549 if (Block) { 1550 if (!FinishBlock(BodyBlock)) 1551 return 0; 1552 } 1553 1554 // If we have no "default:" case, the default transition is to the code 1555 // following the switch body. 1556 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1557 1558 // Add the terminator and condition in the switch block. 1559 SwitchTerminatedBlock->setTerminator(Terminator); 1560 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1561 Block = SwitchTerminatedBlock; 1562 Block = addStmt(Terminator->getCond()); 1563 1564 // Finally, if the SwitchStmt contains a condition variable, add both the 1565 // SwitchStmt and the condition variable initialization to the CFG. 1566 if (VarDecl *VD = Terminator->getConditionVariable()) { 1567 if (Expr *Init = VD->getInit()) { 1568 autoCreateBlock(); 1569 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1570 addStmt(Init); 1571 } 1572 } 1573 1574 return Block; 1575} 1576 1577CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1578 // CaseStmts are essentially labels, so they are the first statement in a 1579 // block. 1580 1581 if (CS->getSubStmt()) 1582 addStmt(CS->getSubStmt()); 1583 1584 CFGBlock* CaseBlock = Block; 1585 if (!CaseBlock) 1586 CaseBlock = createBlock(); 1587 1588 // Cases statements partition blocks, so this is the top of the basic block we 1589 // were processing (the "case XXX:" is the label). 1590 CaseBlock->setLabel(CS); 1591 1592 if (!FinishBlock(CaseBlock)) 1593 return 0; 1594 1595 // Add this block to the list of successors for the block with the switch 1596 // statement. 1597 assert(SwitchTerminatedBlock); 1598 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1599 1600 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1601 Block = NULL; 1602 1603 // This block is now the implicit successor of other blocks. 1604 Succ = CaseBlock; 1605 1606 return CaseBlock; 1607} 1608 1609CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1610 if (Terminator->getSubStmt()) 1611 addStmt(Terminator->getSubStmt()); 1612 1613 DefaultCaseBlock = Block; 1614 1615 if (!DefaultCaseBlock) 1616 DefaultCaseBlock = createBlock(); 1617 1618 // Default statements partition blocks, so this is the top of the basic block 1619 // we were processing (the "default:" is the label). 1620 DefaultCaseBlock->setLabel(Terminator); 1621 1622 if (!FinishBlock(DefaultCaseBlock)) 1623 return 0; 1624 1625 // Unlike case statements, we don't add the default block to the successors 1626 // for the switch statement immediately. This is done when we finish 1627 // processing the switch statement. This allows for the default case 1628 // (including a fall-through to the code after the switch statement) to always 1629 // be the last successor of a switch-terminated block. 1630 1631 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1632 Block = NULL; 1633 1634 // This block is now the implicit successor of other blocks. 1635 Succ = DefaultCaseBlock; 1636 1637 return DefaultCaseBlock; 1638} 1639 1640CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1641 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1642 // current block. 1643 CFGBlock* TrySuccessor = NULL; 1644 1645 if (Block) { 1646 if (!FinishBlock(Block)) 1647 return 0; 1648 TrySuccessor = Block; 1649 } else TrySuccessor = Succ; 1650 1651 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1652 1653 // Create a new block that will contain the try statement. 1654 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1655 // Add the terminator in the try block. 1656 NewTryTerminatedBlock->setTerminator(Terminator); 1657 1658 bool HasCatchAll = false; 1659 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1660 // The code after the try is the implicit successor. 1661 Succ = TrySuccessor; 1662 CXXCatchStmt *CS = Terminator->getHandler(h); 1663 if (CS->getExceptionDecl() == 0) { 1664 HasCatchAll = true; 1665 } 1666 Block = NULL; 1667 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1668 if (CatchBlock == 0) 1669 return 0; 1670 // Add this block to the list of successors for the block with the try 1671 // statement. 1672 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1673 } 1674 if (!HasCatchAll) { 1675 if (PrevTryTerminatedBlock) 1676 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1677 else 1678 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1679 } 1680 1681 // The code after the try is the implicit successor. 1682 Succ = TrySuccessor; 1683 1684 // Save the current "try" context. 1685 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1686 TryTerminatedBlock = NewTryTerminatedBlock; 1687 1688 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1689 Block = NULL; 1690 Block = addStmt(Terminator->getTryBlock()); 1691 return Block; 1692} 1693 1694CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1695 // CXXCatchStmt are treated like labels, so they are the first statement in a 1696 // block. 1697 1698 if (CS->getHandlerBlock()) 1699 addStmt(CS->getHandlerBlock()); 1700 1701 CFGBlock* CatchBlock = Block; 1702 if (!CatchBlock) 1703 CatchBlock = createBlock(); 1704 1705 CatchBlock->setLabel(CS); 1706 1707 if (!FinishBlock(CatchBlock)) 1708 return 0; 1709 1710 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1711 Block = NULL; 1712 1713 return CatchBlock; 1714} 1715 1716CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1717 // Lazily create the indirect-goto dispatch block if there isn't one already. 1718 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1719 1720 if (!IBlock) { 1721 IBlock = createBlock(false); 1722 cfg->setIndirectGotoBlock(IBlock); 1723 } 1724 1725 // IndirectGoto is a control-flow statement. Thus we stop processing the 1726 // current block and create a new one. 1727 if (Block && !FinishBlock(Block)) 1728 return 0; 1729 1730 Block = createBlock(false); 1731 Block->setTerminator(I); 1732 AddSuccessor(Block, IBlock); 1733 return addStmt(I->getTarget()); 1734} 1735 1736} // end anonymous namespace 1737 1738/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1739/// no successors or predecessors. If this is the first block created in the 1740/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1741CFGBlock* CFG::createBlock() { 1742 bool first_block = begin() == end(); 1743 1744 // Create the block. 1745 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1746 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1747 Blocks.push_back(Mem, BlkBVC); 1748 1749 // If this is the first block, set it as the Entry and Exit. 1750 if (first_block) 1751 Entry = Exit = &back(); 1752 1753 // Return the block. 1754 return &back(); 1755} 1756 1757/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1758/// CFG is returned to the caller. 1759CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1760 bool AddEHEdges, bool AddScopes) { 1761 CFGBuilder Builder; 1762 return Builder.buildCFG(D, Statement, C, AddEHEdges, AddScopes); 1763} 1764 1765//===----------------------------------------------------------------------===// 1766// CFG: Queries for BlkExprs. 1767//===----------------------------------------------------------------------===// 1768 1769namespace { 1770 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1771} 1772 1773static void FindSubExprAssignments(Stmt *S, 1774 llvm::SmallPtrSet<Expr*,50>& Set) { 1775 if (!S) 1776 return; 1777 1778 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1779 Stmt *child = *I; 1780 if (!child) 1781 continue; 1782 1783 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1784 if (B->isAssignmentOp()) Set.insert(B); 1785 1786 FindSubExprAssignments(child, Set); 1787 } 1788} 1789 1790static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1791 BlkExprMapTy* M = new BlkExprMapTy(); 1792 1793 // Look for assignments that are used as subexpressions. These are the only 1794 // assignments that we want to *possibly* register as a block-level 1795 // expression. Basically, if an assignment occurs both in a subexpression and 1796 // at the block-level, it is a block-level expression. 1797 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1798 1799 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1800 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1801 FindSubExprAssignments(*BI, SubExprAssignments); 1802 1803 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1804 1805 // Iterate over the statements again on identify the Expr* and Stmt* at the 1806 // block-level that are block-level expressions. 1807 1808 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1809 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1810 1811 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1812 // Assignment expressions that are not nested within another 1813 // expression are really "statements" whose value is never used by 1814 // another expression. 1815 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1816 continue; 1817 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1818 // Special handling for statement expressions. The last statement in 1819 // the statement expression is also a block-level expr. 1820 const CompoundStmt* C = Terminator->getSubStmt(); 1821 if (!C->body_empty()) { 1822 unsigned x = M->size(); 1823 (*M)[C->body_back()] = x; 1824 } 1825 } 1826 1827 unsigned x = M->size(); 1828 (*M)[Exp] = x; 1829 } 1830 1831 // Look at terminators. The condition is a block-level expression. 1832 1833 Stmt* S = (*I)->getTerminatorCondition(); 1834 1835 if (S && M->find(S) == M->end()) { 1836 unsigned x = M->size(); 1837 (*M)[S] = x; 1838 } 1839 } 1840 1841 return M; 1842} 1843 1844CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1845 assert(S != NULL); 1846 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1847 1848 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1849 BlkExprMapTy::iterator I = M->find(S); 1850 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1851} 1852 1853unsigned CFG::getNumBlkExprs() { 1854 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1855 return M->size(); 1856 else { 1857 // We assume callers interested in the number of BlkExprs will want 1858 // the map constructed if it doesn't already exist. 1859 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1860 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1861 } 1862} 1863 1864//===----------------------------------------------------------------------===// 1865// Cleanup: CFG dstor. 1866//===----------------------------------------------------------------------===// 1867 1868CFG::~CFG() { 1869 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1870} 1871 1872//===----------------------------------------------------------------------===// 1873// CFG pretty printing 1874//===----------------------------------------------------------------------===// 1875 1876namespace { 1877 1878class StmtPrinterHelper : public PrinterHelper { 1879 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1880 StmtMapTy StmtMap; 1881 signed CurrentBlock; 1882 unsigned CurrentStmt; 1883 const LangOptions &LangOpts; 1884public: 1885 1886 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1887 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1888 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1889 unsigned j = 1; 1890 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1891 BI != BEnd; ++BI, ++j ) 1892 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1893 } 1894 } 1895 1896 virtual ~StmtPrinterHelper() {} 1897 1898 const LangOptions &getLangOpts() const { return LangOpts; } 1899 void setBlockID(signed i) { CurrentBlock = i; } 1900 void setStmtID(unsigned i) { CurrentStmt = i; } 1901 1902 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1903 1904 StmtMapTy::iterator I = StmtMap.find(Terminator); 1905 1906 if (I == StmtMap.end()) 1907 return false; 1908 1909 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 1910 && I->second.second == CurrentStmt) { 1911 return false; 1912 } 1913 1914 OS << "[B" << I->second.first << "." << I->second.second << "]"; 1915 return true; 1916 } 1917}; 1918} // end anonymous namespace 1919 1920 1921namespace { 1922class CFGBlockTerminatorPrint 1923 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 1924 1925 llvm::raw_ostream& OS; 1926 StmtPrinterHelper* Helper; 1927 PrintingPolicy Policy; 1928public: 1929 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 1930 const PrintingPolicy &Policy) 1931 : OS(os), Helper(helper), Policy(Policy) {} 1932 1933 void VisitIfStmt(IfStmt* I) { 1934 OS << "if "; 1935 I->getCond()->printPretty(OS,Helper,Policy); 1936 } 1937 1938 // Default case. 1939 void VisitStmt(Stmt* Terminator) { 1940 Terminator->printPretty(OS, Helper, Policy); 1941 } 1942 1943 void VisitForStmt(ForStmt* F) { 1944 OS << "for (" ; 1945 if (F->getInit()) 1946 OS << "..."; 1947 OS << "; "; 1948 if (Stmt* C = F->getCond()) 1949 C->printPretty(OS, Helper, Policy); 1950 OS << "; "; 1951 if (F->getInc()) 1952 OS << "..."; 1953 OS << ")"; 1954 } 1955 1956 void VisitWhileStmt(WhileStmt* W) { 1957 OS << "while " ; 1958 if (Stmt* C = W->getCond()) 1959 C->printPretty(OS, Helper, Policy); 1960 } 1961 1962 void VisitDoStmt(DoStmt* D) { 1963 OS << "do ... while "; 1964 if (Stmt* C = D->getCond()) 1965 C->printPretty(OS, Helper, Policy); 1966 } 1967 1968 void VisitSwitchStmt(SwitchStmt* Terminator) { 1969 OS << "switch "; 1970 Terminator->getCond()->printPretty(OS, Helper, Policy); 1971 } 1972 1973 void VisitCXXTryStmt(CXXTryStmt* CS) { 1974 OS << "try ..."; 1975 } 1976 1977 void VisitConditionalOperator(ConditionalOperator* C) { 1978 C->getCond()->printPretty(OS, Helper, Policy); 1979 OS << " ? ... : ..."; 1980 } 1981 1982 void VisitChooseExpr(ChooseExpr* C) { 1983 OS << "__builtin_choose_expr( "; 1984 C->getCond()->printPretty(OS, Helper, Policy); 1985 OS << " )"; 1986 } 1987 1988 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1989 OS << "goto *"; 1990 I->getTarget()->printPretty(OS, Helper, Policy); 1991 } 1992 1993 void VisitBinaryOperator(BinaryOperator* B) { 1994 if (!B->isLogicalOp()) { 1995 VisitExpr(B); 1996 return; 1997 } 1998 1999 B->getLHS()->printPretty(OS, Helper, Policy); 2000 2001 switch (B->getOpcode()) { 2002 case BinaryOperator::LOr: 2003 OS << " || ..."; 2004 return; 2005 case BinaryOperator::LAnd: 2006 OS << " && ..."; 2007 return; 2008 default: 2009 assert(false && "Invalid logical operator."); 2010 } 2011 } 2012 2013 void VisitExpr(Expr* E) { 2014 E->printPretty(OS, Helper, Policy); 2015 } 2016}; 2017} // end anonymous namespace 2018 2019 2020static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2021 const CFGElement &E) { 2022 Stmt *Terminator = E; 2023 2024 if (E.asStartScope()) { 2025 OS << "start scope\n"; 2026 return; 2027 } 2028 if (E.asEndScope()) { 2029 OS << "end scope\n"; 2030 return; 2031 } 2032 2033 if (Helper) { 2034 // special printing for statement-expressions. 2035 if (StmtExpr* SE = dyn_cast<StmtExpr>(Terminator)) { 2036 CompoundStmt* Sub = SE->getSubStmt(); 2037 2038 if (Sub->child_begin() != Sub->child_end()) { 2039 OS << "({ ... ; "; 2040 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2041 OS << " })\n"; 2042 return; 2043 } 2044 } 2045 2046 // special printing for comma expressions. 2047 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Terminator)) { 2048 if (B->getOpcode() == BinaryOperator::Comma) { 2049 OS << "... , "; 2050 Helper->handledStmt(B->getRHS(),OS); 2051 OS << '\n'; 2052 return; 2053 } 2054 } 2055 } 2056 2057 Terminator->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2058 2059 // Expressions need a newline. 2060 if (isa<Expr>(Terminator)) OS << '\n'; 2061} 2062 2063static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2064 const CFGBlock& B, 2065 StmtPrinterHelper* Helper, bool print_edges) { 2066 2067 if (Helper) Helper->setBlockID(B.getBlockID()); 2068 2069 // Print the header. 2070 OS << "\n [ B" << B.getBlockID(); 2071 2072 if (&B == &cfg->getEntry()) 2073 OS << " (ENTRY) ]\n"; 2074 else if (&B == &cfg->getExit()) 2075 OS << " (EXIT) ]\n"; 2076 else if (&B == cfg->getIndirectGotoBlock()) 2077 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2078 else 2079 OS << " ]\n"; 2080 2081 // Print the label of this block. 2082 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2083 2084 if (print_edges) 2085 OS << " "; 2086 2087 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2088 OS << L->getName(); 2089 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2090 OS << "case "; 2091 C->getLHS()->printPretty(OS, Helper, 2092 PrintingPolicy(Helper->getLangOpts())); 2093 if (C->getRHS()) { 2094 OS << " ... "; 2095 C->getRHS()->printPretty(OS, Helper, 2096 PrintingPolicy(Helper->getLangOpts())); 2097 } 2098 } else if (isa<DefaultStmt>(Label)) 2099 OS << "default"; 2100 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2101 OS << "catch ("; 2102 if (CS->getExceptionDecl()) 2103 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2104 0); 2105 else 2106 OS << "..."; 2107 OS << ")"; 2108 2109 } else 2110 assert(false && "Invalid label statement in CFGBlock."); 2111 2112 OS << ":\n"; 2113 } 2114 2115 // Iterate through the statements in the block and print them. 2116 unsigned j = 1; 2117 2118 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2119 I != E ; ++I, ++j ) { 2120 2121 // Print the statement # in the basic block and the statement itself. 2122 if (print_edges) 2123 OS << " "; 2124 2125 OS << llvm::format("%3d", j) << ": "; 2126 2127 if (Helper) 2128 Helper->setStmtID(j); 2129 2130 print_stmt(OS,Helper,*I); 2131 } 2132 2133 // Print the terminator of this block. 2134 if (B.getTerminator()) { 2135 if (print_edges) 2136 OS << " "; 2137 2138 OS << " T: "; 2139 2140 if (Helper) Helper->setBlockID(-1); 2141 2142 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2143 PrintingPolicy(Helper->getLangOpts())); 2144 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2145 OS << '\n'; 2146 } 2147 2148 if (print_edges) { 2149 // Print the predecessors of this block. 2150 OS << " Predecessors (" << B.pred_size() << "):"; 2151 unsigned i = 0; 2152 2153 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2154 I != E; ++I, ++i) { 2155 2156 if (i == 8 || (i-8) == 0) 2157 OS << "\n "; 2158 2159 OS << " B" << (*I)->getBlockID(); 2160 } 2161 2162 OS << '\n'; 2163 2164 // Print the successors of this block. 2165 OS << " Successors (" << B.succ_size() << "):"; 2166 i = 0; 2167 2168 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2169 I != E; ++I, ++i) { 2170 2171 if (i == 8 || (i-8) % 10 == 0) 2172 OS << "\n "; 2173 2174 if (*I) 2175 OS << " B" << (*I)->getBlockID(); 2176 else 2177 OS << " NULL"; 2178 } 2179 2180 OS << '\n'; 2181 } 2182} 2183 2184 2185/// dump - A simple pretty printer of a CFG that outputs to stderr. 2186void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2187 2188/// print - A simple pretty printer of a CFG that outputs to an ostream. 2189void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2190 StmtPrinterHelper Helper(this, LO); 2191 2192 // Print the entry block. 2193 print_block(OS, this, getEntry(), &Helper, true); 2194 2195 // Iterate through the CFGBlocks and print them one by one. 2196 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2197 // Skip the entry block, because we already printed it. 2198 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2199 continue; 2200 2201 print_block(OS, this, **I, &Helper, true); 2202 } 2203 2204 // Print the exit block. 2205 print_block(OS, this, getExit(), &Helper, true); 2206 OS.flush(); 2207} 2208 2209/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2210void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2211 print(llvm::errs(), cfg, LO); 2212} 2213 2214/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2215/// Generally this will only be called from CFG::print. 2216void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2217 const LangOptions &LO) const { 2218 StmtPrinterHelper Helper(cfg, LO); 2219 print_block(OS, cfg, *this, &Helper, true); 2220} 2221 2222/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2223void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2224 const LangOptions &LO) const { 2225 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2226 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2227} 2228 2229Stmt* CFGBlock::getTerminatorCondition() { 2230 2231 if (!Terminator) 2232 return NULL; 2233 2234 Expr* E = NULL; 2235 2236 switch (Terminator->getStmtClass()) { 2237 default: 2238 break; 2239 2240 case Stmt::ForStmtClass: 2241 E = cast<ForStmt>(Terminator)->getCond(); 2242 break; 2243 2244 case Stmt::WhileStmtClass: 2245 E = cast<WhileStmt>(Terminator)->getCond(); 2246 break; 2247 2248 case Stmt::DoStmtClass: 2249 E = cast<DoStmt>(Terminator)->getCond(); 2250 break; 2251 2252 case Stmt::IfStmtClass: 2253 E = cast<IfStmt>(Terminator)->getCond(); 2254 break; 2255 2256 case Stmt::ChooseExprClass: 2257 E = cast<ChooseExpr>(Terminator)->getCond(); 2258 break; 2259 2260 case Stmt::IndirectGotoStmtClass: 2261 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2262 break; 2263 2264 case Stmt::SwitchStmtClass: 2265 E = cast<SwitchStmt>(Terminator)->getCond(); 2266 break; 2267 2268 case Stmt::ConditionalOperatorClass: 2269 E = cast<ConditionalOperator>(Terminator)->getCond(); 2270 break; 2271 2272 case Stmt::BinaryOperatorClass: // '&&' and '||' 2273 E = cast<BinaryOperator>(Terminator)->getLHS(); 2274 break; 2275 2276 case Stmt::ObjCForCollectionStmtClass: 2277 return Terminator; 2278 } 2279 2280 return E ? E->IgnoreParens() : NULL; 2281} 2282 2283bool CFGBlock::hasBinaryBranchTerminator() const { 2284 2285 if (!Terminator) 2286 return false; 2287 2288 Expr* E = NULL; 2289 2290 switch (Terminator->getStmtClass()) { 2291 default: 2292 return false; 2293 2294 case Stmt::ForStmtClass: 2295 case Stmt::WhileStmtClass: 2296 case Stmt::DoStmtClass: 2297 case Stmt::IfStmtClass: 2298 case Stmt::ChooseExprClass: 2299 case Stmt::ConditionalOperatorClass: 2300 case Stmt::BinaryOperatorClass: 2301 return true; 2302 } 2303 2304 return E ? E->IgnoreParens() : NULL; 2305} 2306 2307 2308//===----------------------------------------------------------------------===// 2309// CFG Graphviz Visualization 2310//===----------------------------------------------------------------------===// 2311 2312 2313#ifndef NDEBUG 2314static StmtPrinterHelper* GraphHelper; 2315#endif 2316 2317void CFG::viewCFG(const LangOptions &LO) const { 2318#ifndef NDEBUG 2319 StmtPrinterHelper H(this, LO); 2320 GraphHelper = &H; 2321 llvm::ViewGraph(this,"CFG"); 2322 GraphHelper = NULL; 2323#endif 2324} 2325 2326namespace llvm { 2327template<> 2328struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2329 2330 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2331 2332 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2333 2334#ifndef NDEBUG 2335 std::string OutSStr; 2336 llvm::raw_string_ostream Out(OutSStr); 2337 print_block(Out,Graph, *Node, GraphHelper, false); 2338 std::string& OutStr = Out.str(); 2339 2340 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2341 2342 // Process string output to make it nicer... 2343 for (unsigned i = 0; i != OutStr.length(); ++i) 2344 if (OutStr[i] == '\n') { // Left justify 2345 OutStr[i] = '\\'; 2346 OutStr.insert(OutStr.begin()+i+1, 'l'); 2347 } 2348 2349 return OutStr; 2350#else 2351 return ""; 2352#endif 2353 } 2354}; 2355} // end namespace llvm 2356