CFG.cpp revision 21f6d6ea71b89aeae6b9262c8cbdff7f6328e749
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 *VisitCXXMemberCallExpr(CXXMemberCallExpr *C, AddStmtChoice asc); 115 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 116 CFGBlock *VisitCaseStmt(CaseStmt *C); 117 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 118 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 119 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, AddStmtChoice asc); 120 CFGBlock *VisitContinueStmt(ContinueStmt *C); 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 *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc); 131 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 132 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 133 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 134 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 135 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 136 CFGBlock *VisitReturnStmt(ReturnStmt* R); 137 CFGBlock *VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, AddStmtChoice asc); 138 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 139 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 140 CFGBlock *VisitWhileStmt(WhileStmt *W); 141 142 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 143 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 144 CFGBlock *VisitChildren(Stmt* S); 145 146 // NYS == Not Yet Supported 147 CFGBlock* NYS() { 148 badCFG = true; 149 return Block; 150 } 151 152 CFGBlock *StartScope(Stmt *S, CFGBlock *B) { 153 if (!AddScopes) 154 return B; 155 156 if (B == 0) 157 B = createBlock(); 158 B->StartScope(S, cfg->getBumpVectorContext()); 159 return B; 160 } 161 162 void EndScope(Stmt *S) { 163 if (!AddScopes) 164 return; 165 166 if (Block == 0) 167 Block = createBlock(); 168 Block->EndScope(S, cfg->getBumpVectorContext()); 169 } 170 171 void autoCreateBlock() { if (!Block) Block = createBlock(); } 172 CFGBlock *createBlock(bool add_successor = true); 173 bool FinishBlock(CFGBlock* B); 174 CFGBlock *addStmt(Stmt *S, AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 175 return Visit(S, asc); 176 } 177 178 void AppendStmt(CFGBlock *B, Stmt *S, 179 AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 180 B->appendStmt(S, cfg->getBumpVectorContext(), asc.asLValue()); 181 } 182 183 void AddSuccessor(CFGBlock *B, CFGBlock *S) { 184 B->addSuccessor(S, cfg->getBumpVectorContext()); 185 } 186 187 /// TryResult - a class representing a variant over the values 188 /// 'true', 'false', or 'unknown'. This is returned by TryEvaluateBool, 189 /// and is used by the CFGBuilder to decide if a branch condition 190 /// can be decided up front during CFG construction. 191 class TryResult { 192 int X; 193 public: 194 TryResult(bool b) : X(b ? 1 : 0) {} 195 TryResult() : X(-1) {} 196 197 bool isTrue() const { return X == 1; } 198 bool isFalse() const { return X == 0; } 199 bool isKnown() const { return X >= 0; } 200 void negate() { 201 assert(isKnown()); 202 X ^= 0x1; 203 } 204 }; 205 206 /// TryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 207 /// if we can evaluate to a known value, otherwise return -1. 208 TryResult TryEvaluateBool(Expr *S) { 209 Expr::EvalResult Result; 210 if (!S->isTypeDependent() && !S->isValueDependent() && 211 S->Evaluate(Result, *Context) && Result.Val.isInt()) 212 return Result.Val.getInt().getBoolValue(); 213 214 return TryResult(); 215 } 216 217 bool badCFG; 218 219 // True iff EH edges on CallExprs should be added to the CFG. 220 bool AddEHEdges; 221 222 // True iff scope start and scope end notes should be added to the CFG. 223 bool AddScopes; 224}; 225 226// FIXME: Add support for dependent-sized array types in C++? 227// Does it even make sense to build a CFG for an uninstantiated template? 228static VariableArrayType* FindVA(Type* t) { 229 while (ArrayType* vt = dyn_cast<ArrayType>(t)) { 230 if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt)) 231 if (vat->getSizeExpr()) 232 return vat; 233 234 t = vt->getElementType().getTypePtr(); 235 } 236 237 return 0; 238} 239 240/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 241/// arbitrary statement. Examples include a single expression or a function 242/// body (compound statement). The ownership of the returned CFG is 243/// transferred to the caller. If CFG construction fails, this method returns 244/// NULL. 245CFG* CFGBuilder::buildCFG(const Decl *D, Stmt* Statement, ASTContext* C, 246 bool addehedges, bool AddScopes) { 247 AddEHEdges = addehedges; 248 Context = C; 249 assert(cfg.get()); 250 if (!Statement) 251 return NULL; 252 253 this->AddScopes = AddScopes; 254 badCFG = false; 255 256 // Create an empty block that will serve as the exit block for the CFG. Since 257 // this is the first block added to the CFG, it will be implicitly registered 258 // as the exit block. 259 Succ = createBlock(); 260 assert(Succ == &cfg->getExit()); 261 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 262 263 // Visit the statements and create the CFG. 264 CFGBlock* B = addStmt(Statement); 265 266 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 267 // FIXME: Add code for base initializers and member initializers. 268 (void)CD; 269 } 270 if (!B) 271 B = Succ; 272 273 if (B) { 274 // Finalize the last constructed block. This usually involves reversing the 275 // order of the statements in the block. 276 if (Block) FinishBlock(B); 277 278 // Backpatch the gotos whose label -> block mappings we didn't know when we 279 // encountered them. 280 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 281 E = BackpatchBlocks.end(); I != E; ++I ) { 282 283 CFGBlock* B = *I; 284 GotoStmt* G = cast<GotoStmt>(B->getTerminator()); 285 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 286 287 // If there is no target for the goto, then we are looking at an 288 // incomplete AST. Handle this by not registering a successor. 289 if (LI == LabelMap.end()) continue; 290 291 AddSuccessor(B, LI->second); 292 } 293 294 // Add successors to the Indirect Goto Dispatch block (if we have one). 295 if (CFGBlock* B = cfg->getIndirectGotoBlock()) 296 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 297 E = AddressTakenLabels.end(); I != E; ++I ) { 298 299 // Lookup the target block. 300 LabelMapTy::iterator LI = LabelMap.find(*I); 301 302 // If there is no target block that contains label, then we are looking 303 // at an incomplete AST. Handle this by not registering a successor. 304 if (LI == LabelMap.end()) continue; 305 306 AddSuccessor(B, LI->second); 307 } 308 309 Succ = B; 310 } 311 312 // Create an empty entry block that has no predecessors. 313 cfg->setEntry(createBlock()); 314 315 return badCFG ? NULL : cfg.take(); 316} 317 318/// createBlock - Used to lazily create blocks that are connected 319/// to the current (global) succcessor. 320CFGBlock* CFGBuilder::createBlock(bool add_successor) { 321 CFGBlock* B = cfg->createBlock(); 322 if (add_successor && Succ) 323 AddSuccessor(B, Succ); 324 return B; 325} 326 327/// FinishBlock - "Finalize" the block by checking if we have a bad CFG. 328bool CFGBuilder::FinishBlock(CFGBlock* B) { 329 if (badCFG) 330 return false; 331 332 assert(B); 333 return true; 334} 335 336/// Visit - Walk the subtree of a statement and add extra 337/// blocks for ternary operators, &&, and ||. We also process "," and 338/// DeclStmts (which may contain nested control-flow). 339CFGBlock* CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 340tryAgain: 341 switch (S->getStmtClass()) { 342 default: 343 return VisitStmt(S, asc); 344 345 case Stmt::AddrLabelExprClass: 346 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 347 348 case Stmt::BinaryOperatorClass: 349 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 350 351 case Stmt::BlockExprClass: 352 return VisitBlockExpr(cast<BlockExpr>(S), asc); 353 354 case Stmt::BreakStmtClass: 355 return VisitBreakStmt(cast<BreakStmt>(S)); 356 357 case Stmt::CallExprClass: 358 return VisitCallExpr(cast<CallExpr>(S), asc); 359 360 case Stmt::CaseStmtClass: 361 return VisitCaseStmt(cast<CaseStmt>(S)); 362 363 case Stmt::ChooseExprClass: 364 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 365 366 case Stmt::CompoundStmtClass: 367 return VisitCompoundStmt(cast<CompoundStmt>(S)); 368 369 case Stmt::ConditionalOperatorClass: 370 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 371 372 case Stmt::ContinueStmtClass: 373 return VisitContinueStmt(cast<ContinueStmt>(S)); 374 375 case Stmt::CXXCatchStmtClass: 376 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 377 378 case Stmt::CXXMemberCallExprClass: 379 return VisitCXXMemberCallExpr(cast<CXXMemberCallExpr>(S), asc); 380 381 case Stmt::CXXThrowExprClass: 382 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 383 384 case Stmt::CXXTryStmtClass: 385 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 386 387 case Stmt::DeclStmtClass: 388 return VisitDeclStmt(cast<DeclStmt>(S)); 389 390 case Stmt::DefaultStmtClass: 391 return VisitDefaultStmt(cast<DefaultStmt>(S)); 392 393 case Stmt::DoStmtClass: 394 return VisitDoStmt(cast<DoStmt>(S)); 395 396 case Stmt::ForStmtClass: 397 return VisitForStmt(cast<ForStmt>(S)); 398 399 case Stmt::GotoStmtClass: 400 return VisitGotoStmt(cast<GotoStmt>(S)); 401 402 case Stmt::IfStmtClass: 403 return VisitIfStmt(cast<IfStmt>(S)); 404 405 case Stmt::IndirectGotoStmtClass: 406 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 407 408 case Stmt::LabelStmtClass: 409 return VisitLabelStmt(cast<LabelStmt>(S)); 410 411 case Stmt::MemberExprClass: 412 return VisitMemberExpr(cast<MemberExpr>(S), asc); 413 414 case Stmt::ObjCAtCatchStmtClass: 415 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 416 417 case Stmt::ObjCAtSynchronizedStmtClass: 418 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 419 420 case Stmt::ObjCAtThrowStmtClass: 421 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 422 423 case Stmt::ObjCAtTryStmtClass: 424 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 425 426 case Stmt::ObjCForCollectionStmtClass: 427 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 428 429 case Stmt::ParenExprClass: 430 S = cast<ParenExpr>(S)->getSubExpr(); 431 goto tryAgain; 432 433 case Stmt::NullStmtClass: 434 return Block; 435 436 case Stmt::ReturnStmtClass: 437 return VisitReturnStmt(cast<ReturnStmt>(S)); 438 439 case Stmt::SizeOfAlignOfExprClass: 440 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 441 442 case Stmt::StmtExprClass: 443 return VisitStmtExpr(cast<StmtExpr>(S), asc); 444 445 case Stmt::SwitchStmtClass: 446 return VisitSwitchStmt(cast<SwitchStmt>(S)); 447 448 case Stmt::WhileStmtClass: 449 return VisitWhileStmt(cast<WhileStmt>(S)); 450 } 451} 452 453CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 454 if (asc.alwaysAdd()) { 455 autoCreateBlock(); 456 AppendStmt(Block, S, asc); 457 } 458 459 return VisitChildren(S); 460} 461 462/// VisitChildren - Visit the children of a Stmt. 463CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 464 CFGBlock *B = Block; 465 for (Stmt::child_iterator I = Terminator->child_begin(), 466 E = Terminator->child_end(); I != E; ++I) { 467 if (*I) B = Visit(*I); 468 } 469 return B; 470} 471 472CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 473 AddStmtChoice asc) { 474 AddressTakenLabels.insert(A->getLabel()); 475 476 if (asc.alwaysAdd()) { 477 autoCreateBlock(); 478 AppendStmt(Block, A, asc); 479 } 480 481 return Block; 482} 483 484CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 485 AddStmtChoice asc) { 486 if (B->isLogicalOp()) { // && or || 487 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 488 AppendStmt(ConfluenceBlock, B, asc); 489 490 if (!FinishBlock(ConfluenceBlock)) 491 return 0; 492 493 // create the block evaluating the LHS 494 CFGBlock* LHSBlock = createBlock(false); 495 LHSBlock->setTerminator(B); 496 497 // create the block evaluating the RHS 498 Succ = ConfluenceBlock; 499 Block = NULL; 500 CFGBlock* RHSBlock = addStmt(B->getRHS()); 501 if (!FinishBlock(RHSBlock)) 502 return 0; 503 504 // See if this is a known constant. 505 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 506 if (KnownVal.isKnown() && (B->getOpcode() == BinaryOperator::LOr)) 507 KnownVal.negate(); 508 509 // Now link the LHSBlock with RHSBlock. 510 if (B->getOpcode() == BinaryOperator::LOr) { 511 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 512 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 513 } else { 514 assert(B->getOpcode() == BinaryOperator::LAnd); 515 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 516 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 517 } 518 519 // Generate the blocks for evaluating the LHS. 520 Block = LHSBlock; 521 return addStmt(B->getLHS()); 522 } 523 else if (B->getOpcode() == BinaryOperator::Comma) { // , 524 autoCreateBlock(); 525 AppendStmt(Block, B, asc); 526 addStmt(B->getRHS()); 527 return addStmt(B->getLHS()); 528 } 529 530 return VisitStmt(B, asc); 531} 532 533CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 534 if (asc.alwaysAdd()) { 535 autoCreateBlock(); 536 AppendStmt(Block, E, asc); 537 } 538 return Block; 539} 540 541CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 542 // "break" is a control-flow statement. Thus we stop processing the current 543 // block. 544 if (Block && !FinishBlock(Block)) 545 return 0; 546 547 // Now create a new block that ends with the break statement. 548 Block = createBlock(false); 549 Block->setTerminator(B); 550 551 // If there is no target for the break, then we are looking at an incomplete 552 // AST. This means that the CFG cannot be constructed. 553 if (BreakTargetBlock) 554 AddSuccessor(Block, BreakTargetBlock); 555 else 556 badCFG = true; 557 558 559 return Block; 560} 561 562static bool CanThrow(Expr *E) { 563 QualType Ty = E->getType(); 564 if (Ty->isFunctionPointerType()) 565 Ty = Ty->getAs<PointerType>()->getPointeeType(); 566 else if (Ty->isBlockPointerType()) 567 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 568 569 const FunctionType *FT = Ty->getAs<FunctionType>(); 570 if (FT) { 571 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 572 if (Proto->hasEmptyExceptionSpec()) 573 return false; 574 } 575 return true; 576} 577 578CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 579 // If this is a call to a no-return function, this stops the block here. 580 bool NoReturn = false; 581 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 582 NoReturn = true; 583 } 584 585 bool AddEHEdge = false; 586 587 // Languages without exceptions are assumed to not throw. 588 if (Context->getLangOptions().Exceptions) { 589 if (AddEHEdges) 590 AddEHEdge = true; 591 } 592 593 if (FunctionDecl *FD = C->getDirectCallee()) { 594 if (FD->hasAttr<NoReturnAttr>()) 595 NoReturn = true; 596 if (FD->hasAttr<NoThrowAttr>()) 597 AddEHEdge = false; 598 } 599 600 if (!CanThrow(C->getCallee())) 601 AddEHEdge = false; 602 603 if (!NoReturn && !AddEHEdge) 604 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 605 606 if (Block) { 607 Succ = Block; 608 if (!FinishBlock(Block)) 609 return 0; 610 } 611 612 Block = createBlock(!NoReturn); 613 AppendStmt(Block, C, asc); 614 615 if (NoReturn) { 616 // Wire this to the exit block directly. 617 AddSuccessor(Block, &cfg->getExit()); 618 } 619 if (AddEHEdge) { 620 // Add exceptional edges. 621 if (TryTerminatedBlock) 622 AddSuccessor(Block, TryTerminatedBlock); 623 else 624 AddSuccessor(Block, &cfg->getExit()); 625 } 626 627 return VisitChildren(C); 628} 629 630CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 631 AddStmtChoice asc) { 632 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 633 AppendStmt(ConfluenceBlock, C, asc); 634 if (!FinishBlock(ConfluenceBlock)) 635 return 0; 636 637 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 638 : AddStmtChoice::AlwaysAdd; 639 640 Succ = ConfluenceBlock; 641 Block = NULL; 642 CFGBlock* LHSBlock = addStmt(C->getLHS(), asc); 643 if (!FinishBlock(LHSBlock)) 644 return 0; 645 646 Succ = ConfluenceBlock; 647 Block = NULL; 648 CFGBlock* RHSBlock = addStmt(C->getRHS(), asc); 649 if (!FinishBlock(RHSBlock)) 650 return 0; 651 652 Block = createBlock(false); 653 // See if this is a known constant. 654 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 655 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 656 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 657 Block->setTerminator(C); 658 return addStmt(C->getCond()); 659} 660 661 662CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 663 EndScope(C); 664 665 CFGBlock* LastBlock = Block; 666 667 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 668 I != E; ++I ) { 669 LastBlock = addStmt(*I); 670 671 if (badCFG) 672 return NULL; 673 } 674 675 LastBlock = StartScope(C, LastBlock); 676 677 return LastBlock; 678} 679 680CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 681 AddStmtChoice asc) { 682 // Create the confluence block that will "merge" the results of the ternary 683 // expression. 684 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 685 AppendStmt(ConfluenceBlock, C, asc); 686 if (!FinishBlock(ConfluenceBlock)) 687 return 0; 688 689 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 690 : AddStmtChoice::AlwaysAdd; 691 692 // Create a block for the LHS expression if there is an LHS expression. A 693 // GCC extension allows LHS to be NULL, causing the condition to be the 694 // value that is returned instead. 695 // e.g: x ?: y is shorthand for: x ? x : y; 696 Succ = ConfluenceBlock; 697 Block = NULL; 698 CFGBlock* LHSBlock = NULL; 699 if (C->getLHS()) { 700 LHSBlock = addStmt(C->getLHS(), asc); 701 if (!FinishBlock(LHSBlock)) 702 return 0; 703 Block = NULL; 704 } 705 706 // Create the block for the RHS expression. 707 Succ = ConfluenceBlock; 708 CFGBlock* RHSBlock = addStmt(C->getRHS(), asc); 709 if (!FinishBlock(RHSBlock)) 710 return 0; 711 712 // Create the block that will contain the condition. 713 Block = createBlock(false); 714 715 // See if this is a known constant. 716 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 717 if (LHSBlock) { 718 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 719 } else { 720 if (KnownVal.isFalse()) { 721 // If we know the condition is false, add NULL as the successor for 722 // the block containing the condition. In this case, the confluence 723 // block will have just one predecessor. 724 AddSuccessor(Block, 0); 725 assert(ConfluenceBlock->pred_size() == 1); 726 } else { 727 // If we have no LHS expression, add the ConfluenceBlock as a direct 728 // successor for the block containing the condition. Moreover, we need to 729 // reverse the order of the predecessors in the ConfluenceBlock because 730 // the RHSBlock will have been added to the succcessors already, and we 731 // want the first predecessor to the the block containing the expression 732 // for the case when the ternary expression evaluates to true. 733 AddSuccessor(Block, ConfluenceBlock); 734 assert(ConfluenceBlock->pred_size() == 2); 735 std::reverse(ConfluenceBlock->pred_begin(), 736 ConfluenceBlock->pred_end()); 737 } 738 } 739 740 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 741 Block->setTerminator(C); 742 return addStmt(C->getCond()); 743} 744 745CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 746 autoCreateBlock(); 747 748 if (DS->isSingleDecl()) { 749 AppendStmt(Block, DS); 750 return VisitDeclSubExpr(DS->getSingleDecl()); 751 } 752 753 CFGBlock *B = 0; 754 755 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 756 typedef llvm::SmallVector<Decl*,10> BufTy; 757 BufTy Buf(DS->decl_begin(), DS->decl_end()); 758 759 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 760 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 761 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 762 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 763 764 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 765 // automatically freed with the CFG. 766 DeclGroupRef DG(*I); 767 Decl *D = *I; 768 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 769 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 770 771 // Append the fake DeclStmt to block. 772 AppendStmt(Block, DSNew); 773 B = VisitDeclSubExpr(D); 774 } 775 776 return B; 777} 778 779/// VisitDeclSubExpr - Utility method to add block-level expressions for 780/// initializers in Decls. 781CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 782 assert(Block); 783 784 VarDecl *VD = dyn_cast<VarDecl>(D); 785 786 if (!VD) 787 return Block; 788 789 Expr *Init = VD->getInit(); 790 791 if (Init) { 792 AddStmtChoice::Kind k = 793 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 794 : AddStmtChoice::NotAlwaysAdd; 795 Visit(Init, AddStmtChoice(k)); 796 } 797 798 // If the type of VD is a VLA, then we must process its size expressions. 799 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 800 VA = FindVA(VA->getElementType().getTypePtr())) 801 Block = addStmt(VA->getSizeExpr()); 802 803 return Block; 804} 805 806CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 807 // We may see an if statement in the middle of a basic block, or it may be the 808 // first statement we are processing. In either case, we create a new basic 809 // block. First, we create the blocks for the then...else statements, and 810 // then we create the block containing the if statement. If we were in the 811 // middle of a block, we stop processing that block. That block is then the 812 // implicit successor for the "then" and "else" clauses. 813 814 // The block we were proccessing is now finished. Make it the successor 815 // block. 816 if (Block) { 817 Succ = Block; 818 if (!FinishBlock(Block)) 819 return 0; 820 } 821 822 // Process the false branch. 823 CFGBlock* ElseBlock = Succ; 824 825 if (Stmt* Else = I->getElse()) { 826 SaveAndRestore<CFGBlock*> sv(Succ); 827 828 // NULL out Block so that the recursive call to Visit will 829 // create a new basic block. 830 Block = NULL; 831 ElseBlock = addStmt(Else); 832 833 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 834 ElseBlock = sv.get(); 835 else if (Block) { 836 if (!FinishBlock(ElseBlock)) 837 return 0; 838 } 839 } 840 841 // Process the true branch. 842 CFGBlock* ThenBlock; 843 { 844 Stmt* Then = I->getThen(); 845 assert(Then); 846 SaveAndRestore<CFGBlock*> sv(Succ); 847 Block = NULL; 848 ThenBlock = addStmt(Then); 849 850 if (!ThenBlock) { 851 // We can reach here if the "then" body has all NullStmts. 852 // Create an empty block so we can distinguish between true and false 853 // branches in path-sensitive analyses. 854 ThenBlock = createBlock(false); 855 AddSuccessor(ThenBlock, sv.get()); 856 } else if (Block) { 857 if (!FinishBlock(ThenBlock)) 858 return 0; 859 } 860 } 861 862 // Now create a new block containing the if statement. 863 Block = createBlock(false); 864 865 // Set the terminator of the new block to the If statement. 866 Block->setTerminator(I); 867 868 // See if this is a known constant. 869 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 870 871 // Now add the successors. 872 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 873 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 874 875 // Add the condition as the last statement in the new block. This may create 876 // new blocks as the condition may contain control-flow. Any newly created 877 // blocks will be pointed to be "Block". 878 Block = addStmt(I->getCond()); 879 880 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 881 // and the condition variable initialization to the CFG. 882 if (VarDecl *VD = I->getConditionVariable()) { 883 if (Expr *Init = VD->getInit()) { 884 autoCreateBlock(); 885 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 886 addStmt(Init); 887 } 888 } 889 890 return Block; 891} 892 893 894CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 895 // If we were in the middle of a block we stop processing that block. 896 // 897 // NOTE: If a "return" appears in the middle of a block, this means that the 898 // code afterwards is DEAD (unreachable). We still keep a basic block 899 // for that code; a simple "mark-and-sweep" from the entry block will be 900 // able to report such dead blocks. 901 if (Block) 902 FinishBlock(Block); 903 904 // Create the new block. 905 Block = createBlock(false); 906 907 // The Exit block is the only successor. 908 AddSuccessor(Block, &cfg->getExit()); 909 910 // Add the return statement to the block. This may create new blocks if R 911 // contains control-flow (short-circuit operations). 912 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 913} 914 915CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 916 // Get the block of the labeled statement. Add it to our map. 917 addStmt(L->getSubStmt()); 918 CFGBlock* LabelBlock = Block; 919 920 if (!LabelBlock) // This can happen when the body is empty, i.e. 921 LabelBlock = createBlock(); // scopes that only contains NullStmts. 922 923 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 924 LabelMap[ L ] = LabelBlock; 925 926 // Labels partition blocks, so this is the end of the basic block we were 927 // processing (L is the block's label). Because this is label (and we have 928 // already processed the substatement) there is no extra control-flow to worry 929 // about. 930 LabelBlock->setLabel(L); 931 if (!FinishBlock(LabelBlock)) 932 return 0; 933 934 // We set Block to NULL to allow lazy creation of a new block (if necessary); 935 Block = NULL; 936 937 // This block is now the implicit successor of other blocks. 938 Succ = LabelBlock; 939 940 return LabelBlock; 941} 942 943CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 944 // Goto is a control-flow statement. Thus we stop processing the current 945 // block and create a new one. 946 if (Block) 947 FinishBlock(Block); 948 949 Block = createBlock(false); 950 Block->setTerminator(G); 951 952 // If we already know the mapping to the label block add the successor now. 953 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 954 955 if (I == LabelMap.end()) 956 // We will need to backpatch this block later. 957 BackpatchBlocks.push_back(Block); 958 else 959 AddSuccessor(Block, I->second); 960 961 return Block; 962} 963 964CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 965 CFGBlock* LoopSuccessor = NULL; 966 967 // "for" is a control-flow statement. Thus we stop processing the current 968 // block. 969 if (Block) { 970 if (!FinishBlock(Block)) 971 return 0; 972 LoopSuccessor = Block; 973 } else 974 LoopSuccessor = Succ; 975 976 // Because of short-circuit evaluation, the condition of the loop can span 977 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 978 // evaluate the condition. 979 CFGBlock* ExitConditionBlock = createBlock(false); 980 CFGBlock* EntryConditionBlock = ExitConditionBlock; 981 982 // Set the terminator for the "exit" condition block. 983 ExitConditionBlock->setTerminator(F); 984 985 // Now add the actual condition to the condition block. Because the condition 986 // itself may contain control-flow, new blocks may be created. 987 if (Stmt* C = F->getCond()) { 988 Block = ExitConditionBlock; 989 EntryConditionBlock = addStmt(C); 990 assert(Block == EntryConditionBlock); 991 992 // If this block contains a condition variable, add both the condition 993 // variable and initializer to the CFG. 994 if (VarDecl *VD = F->getConditionVariable()) { 995 if (Expr *Init = VD->getInit()) { 996 autoCreateBlock(); 997 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 998 EntryConditionBlock = addStmt(Init); 999 assert(Block == EntryConditionBlock); 1000 } 1001 } 1002 1003 if (Block) { 1004 if (!FinishBlock(EntryConditionBlock)) 1005 return 0; 1006 } 1007 } 1008 1009 // The condition block is the implicit successor for the loop body as well as 1010 // any code above the loop. 1011 Succ = EntryConditionBlock; 1012 1013 // See if this is a known constant. 1014 TryResult KnownVal(true); 1015 1016 if (F->getCond()) 1017 KnownVal = TryEvaluateBool(F->getCond()); 1018 1019 // Now create the loop body. 1020 { 1021 assert(F->getBody()); 1022 1023 // Save the current values for Block, Succ, and continue and break targets 1024 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1025 save_continue(ContinueTargetBlock), 1026 save_break(BreakTargetBlock); 1027 1028 // Create a new block to contain the (bottom) of the loop body. 1029 Block = NULL; 1030 1031 if (Stmt* I = F->getInc()) { 1032 // Generate increment code in its own basic block. This is the target of 1033 // continue statements. 1034 Succ = addStmt(I); 1035 } else { 1036 // No increment code. Create a special, empty, block that is used as the 1037 // target block for "looping back" to the start of the loop. 1038 assert(Succ == EntryConditionBlock); 1039 Succ = createBlock(); 1040 } 1041 1042 // Finish up the increment (or empty) block if it hasn't been already. 1043 if (Block) { 1044 assert(Block == Succ); 1045 if (!FinishBlock(Block)) 1046 return 0; 1047 Block = 0; 1048 } 1049 1050 ContinueTargetBlock = Succ; 1051 1052 // The starting block for the loop increment is the block that should 1053 // represent the 'loop target' for looping back to the start of the loop. 1054 ContinueTargetBlock->setLoopTarget(F); 1055 1056 // All breaks should go to the code following the loop. 1057 BreakTargetBlock = LoopSuccessor; 1058 1059 // Now populate the body block, and in the process create new blocks as we 1060 // walk the body of the loop. 1061 CFGBlock* BodyBlock = addStmt(F->getBody()); 1062 1063 if (!BodyBlock) 1064 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1065 else if (Block && !FinishBlock(BodyBlock)) 1066 return 0; 1067 1068 // This new body block is a successor to our "exit" condition block. 1069 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1070 } 1071 1072 // Link up the condition block with the code that follows the loop. (the 1073 // false branch). 1074 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1075 1076 // If the loop contains initialization, create a new block for those 1077 // statements. This block can also contain statements that precede the loop. 1078 if (Stmt* I = F->getInit()) { 1079 Block = createBlock(); 1080 return addStmt(I); 1081 } else { 1082 // There is no loop initialization. We are thus basically a while loop. 1083 // NULL out Block to force lazy block construction. 1084 Block = NULL; 1085 Succ = EntryConditionBlock; 1086 return EntryConditionBlock; 1087 } 1088} 1089 1090CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) { 1091 if (asc.alwaysAdd()) { 1092 autoCreateBlock(); 1093 AppendStmt(Block, M, asc); 1094 } 1095 return Visit(M->getBase(), 1096 M->isArrow() ? AddStmtChoice::NotAlwaysAdd 1097 : AddStmtChoice::AsLValueNotAlwaysAdd); 1098} 1099 1100CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1101 // Objective-C fast enumeration 'for' statements: 1102 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1103 // 1104 // for ( Type newVariable in collection_expression ) { statements } 1105 // 1106 // becomes: 1107 // 1108 // prologue: 1109 // 1. collection_expression 1110 // T. jump to loop_entry 1111 // loop_entry: 1112 // 1. side-effects of element expression 1113 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1114 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1115 // TB: 1116 // statements 1117 // T. jump to loop_entry 1118 // FB: 1119 // what comes after 1120 // 1121 // and 1122 // 1123 // Type existingItem; 1124 // for ( existingItem in expression ) { statements } 1125 // 1126 // becomes: 1127 // 1128 // the same with newVariable replaced with existingItem; the binding works 1129 // the same except that for one ObjCForCollectionStmt::getElement() returns 1130 // a DeclStmt and the other returns a DeclRefExpr. 1131 // 1132 1133 CFGBlock* LoopSuccessor = 0; 1134 1135 if (Block) { 1136 if (!FinishBlock(Block)) 1137 return 0; 1138 LoopSuccessor = Block; 1139 Block = 0; 1140 } else 1141 LoopSuccessor = Succ; 1142 1143 // Build the condition blocks. 1144 CFGBlock* ExitConditionBlock = createBlock(false); 1145 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1146 1147 // Set the terminator for the "exit" condition block. 1148 ExitConditionBlock->setTerminator(S); 1149 1150 // The last statement in the block should be the ObjCForCollectionStmt, which 1151 // performs the actual binding to 'element' and determines if there are any 1152 // more items in the collection. 1153 AppendStmt(ExitConditionBlock, S); 1154 Block = ExitConditionBlock; 1155 1156 // Walk the 'element' expression to see if there are any side-effects. We 1157 // generate new blocks as necesary. We DON'T add the statement by default to 1158 // the CFG unless it contains control-flow. 1159 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1160 if (Block) { 1161 if (!FinishBlock(EntryConditionBlock)) 1162 return 0; 1163 Block = 0; 1164 } 1165 1166 // The condition block is the implicit successor for the loop body as well as 1167 // any code above the loop. 1168 Succ = EntryConditionBlock; 1169 1170 // Now create the true branch. 1171 { 1172 // Save the current values for Succ, continue and break targets. 1173 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1174 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1175 1176 BreakTargetBlock = LoopSuccessor; 1177 ContinueTargetBlock = EntryConditionBlock; 1178 1179 CFGBlock* BodyBlock = addStmt(S->getBody()); 1180 1181 if (!BodyBlock) 1182 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1183 else if (Block) { 1184 if (!FinishBlock(BodyBlock)) 1185 return 0; 1186 } 1187 1188 // This new body block is a successor to our "exit" condition block. 1189 AddSuccessor(ExitConditionBlock, BodyBlock); 1190 } 1191 1192 // Link up the condition block with the code that follows the loop. 1193 // (the false branch). 1194 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1195 1196 // Now create a prologue block to contain the collection expression. 1197 Block = createBlock(); 1198 return addStmt(S->getCollection()); 1199} 1200 1201CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1202 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1203 1204 // Inline the body. 1205 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1206 1207 // The sync body starts its own basic block. This makes it a little easier 1208 // for diagnostic clients. 1209 if (SyncBlock) { 1210 if (!FinishBlock(SyncBlock)) 1211 return 0; 1212 1213 Block = 0; 1214 } 1215 1216 Succ = SyncBlock; 1217 1218 // Inline the sync expression. 1219 return addStmt(S->getSynchExpr()); 1220} 1221 1222CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1223 // FIXME 1224 return NYS(); 1225} 1226 1227CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1228 CFGBlock* LoopSuccessor = NULL; 1229 1230 // "while" is a control-flow statement. Thus we stop processing the current 1231 // block. 1232 if (Block) { 1233 if (!FinishBlock(Block)) 1234 return 0; 1235 LoopSuccessor = Block; 1236 } else 1237 LoopSuccessor = Succ; 1238 1239 // Because of short-circuit evaluation, the condition of the loop can span 1240 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1241 // evaluate the condition. 1242 CFGBlock* ExitConditionBlock = createBlock(false); 1243 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1244 1245 // Set the terminator for the "exit" condition block. 1246 ExitConditionBlock->setTerminator(W); 1247 1248 // Now add the actual condition to the condition block. Because the condition 1249 // itself may contain control-flow, new blocks may be created. Thus we update 1250 // "Succ" after adding the condition. 1251 if (Stmt* C = W->getCond()) { 1252 Block = ExitConditionBlock; 1253 EntryConditionBlock = addStmt(C); 1254 assert(Block == EntryConditionBlock); 1255 1256 // If this block contains a condition variable, add both the condition 1257 // variable and initializer to the CFG. 1258 if (VarDecl *VD = W->getConditionVariable()) { 1259 if (Expr *Init = VD->getInit()) { 1260 autoCreateBlock(); 1261 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1262 EntryConditionBlock = addStmt(Init); 1263 assert(Block == EntryConditionBlock); 1264 } 1265 } 1266 1267 if (Block) { 1268 if (!FinishBlock(EntryConditionBlock)) 1269 return 0; 1270 } 1271 } 1272 1273 // The condition block is the implicit successor for the loop body as well as 1274 // any code above the loop. 1275 Succ = EntryConditionBlock; 1276 1277 // See if this is a known constant. 1278 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1279 1280 // Process the loop body. 1281 { 1282 assert(W->getBody()); 1283 1284 // Save the current values for Block, Succ, and continue and break targets 1285 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1286 save_continue(ContinueTargetBlock), 1287 save_break(BreakTargetBlock); 1288 1289 // Create an empty block to represent the transition block for looping back 1290 // to the head of the loop. 1291 Block = 0; 1292 assert(Succ == EntryConditionBlock); 1293 Succ = createBlock(); 1294 Succ->setLoopTarget(W); 1295 ContinueTargetBlock = Succ; 1296 1297 // All breaks should go to the code following the loop. 1298 BreakTargetBlock = LoopSuccessor; 1299 1300 // NULL out Block to force lazy instantiation of blocks for the body. 1301 Block = NULL; 1302 1303 // Create the body. The returned block is the entry to the loop body. 1304 CFGBlock* BodyBlock = addStmt(W->getBody()); 1305 1306 if (!BodyBlock) 1307 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1308 else if (Block) { 1309 if (!FinishBlock(BodyBlock)) 1310 return 0; 1311 } 1312 1313 // Add the loop body entry as a successor to the condition. 1314 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1315 } 1316 1317 // Link up the condition block with the code that follows the loop. (the 1318 // false branch). 1319 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1320 1321 // There can be no more statements in the condition block since we loop back 1322 // to this block. NULL out Block to force lazy creation of another block. 1323 Block = NULL; 1324 1325 // Return the condition block, which is the dominating block for the loop. 1326 Succ = EntryConditionBlock; 1327 return EntryConditionBlock; 1328} 1329 1330 1331CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1332 // FIXME: For now we pretend that @catch and the code it contains does not 1333 // exit. 1334 return Block; 1335} 1336 1337CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1338 // FIXME: This isn't complete. We basically treat @throw like a return 1339 // statement. 1340 1341 // If we were in the middle of a block we stop processing that block. 1342 if (Block && !FinishBlock(Block)) 1343 return 0; 1344 1345 // Create the new block. 1346 Block = createBlock(false); 1347 1348 // The Exit block is the only successor. 1349 AddSuccessor(Block, &cfg->getExit()); 1350 1351 // Add the statement to the block. This may create new blocks if S contains 1352 // control-flow (short-circuit operations). 1353 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1354} 1355 1356CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1357 // If we were in the middle of a block we stop processing that block. 1358 if (Block && !FinishBlock(Block)) 1359 return 0; 1360 1361 // Create the new block. 1362 Block = createBlock(false); 1363 1364 if (TryTerminatedBlock) 1365 // The current try statement is the only successor. 1366 AddSuccessor(Block, TryTerminatedBlock); 1367 else 1368 // otherwise the Exit block is the only successor. 1369 AddSuccessor(Block, &cfg->getExit()); 1370 1371 // Add the statement to the block. This may create new blocks if S contains 1372 // control-flow (short-circuit operations). 1373 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1374} 1375 1376CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1377 CFGBlock* LoopSuccessor = NULL; 1378 1379 // "do...while" is a control-flow statement. Thus we stop processing the 1380 // current block. 1381 if (Block) { 1382 if (!FinishBlock(Block)) 1383 return 0; 1384 LoopSuccessor = Block; 1385 } else 1386 LoopSuccessor = Succ; 1387 1388 // Because of short-circuit evaluation, the condition of the loop can span 1389 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1390 // evaluate the condition. 1391 CFGBlock* ExitConditionBlock = createBlock(false); 1392 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1393 1394 // Set the terminator for the "exit" condition block. 1395 ExitConditionBlock->setTerminator(D); 1396 1397 // Now add the actual condition to the condition block. Because the condition 1398 // itself may contain control-flow, new blocks may be created. 1399 if (Stmt* C = D->getCond()) { 1400 Block = ExitConditionBlock; 1401 EntryConditionBlock = addStmt(C); 1402 if (Block) { 1403 if (!FinishBlock(EntryConditionBlock)) 1404 return 0; 1405 } 1406 } 1407 1408 // The condition block is the implicit successor for the loop body. 1409 Succ = EntryConditionBlock; 1410 1411 // See if this is a known constant. 1412 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1413 1414 // Process the loop body. 1415 CFGBlock* BodyBlock = NULL; 1416 { 1417 assert(D->getBody()); 1418 1419 // Save the current values for Block, Succ, and continue and break targets 1420 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1421 save_continue(ContinueTargetBlock), 1422 save_break(BreakTargetBlock); 1423 1424 // All continues within this loop should go to the condition block 1425 ContinueTargetBlock = EntryConditionBlock; 1426 1427 // All breaks should go to the code following the loop. 1428 BreakTargetBlock = LoopSuccessor; 1429 1430 // NULL out Block to force lazy instantiation of blocks for the body. 1431 Block = NULL; 1432 1433 // Create the body. The returned block is the entry to the loop body. 1434 BodyBlock = addStmt(D->getBody()); 1435 1436 if (!BodyBlock) 1437 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1438 else if (Block) { 1439 if (!FinishBlock(BodyBlock)) 1440 return 0; 1441 } 1442 1443 // Add an intermediate block between the BodyBlock and the 1444 // ExitConditionBlock to represent the "loop back" transition. Create an 1445 // empty block to represent the transition block for looping back to the 1446 // head of the loop. 1447 // FIXME: Can we do this more efficiently without adding another block? 1448 Block = NULL; 1449 Succ = BodyBlock; 1450 CFGBlock *LoopBackBlock = createBlock(); 1451 LoopBackBlock->setLoopTarget(D); 1452 1453 // Add the loop body entry as a successor to the condition. 1454 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : LoopBackBlock); 1455 } 1456 1457 // Link up the condition block with the code that follows the loop. 1458 // (the false branch). 1459 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1460 1461 // There can be no more statements in the body block(s) since we loop back to 1462 // the body. NULL out Block to force lazy creation of another block. 1463 Block = NULL; 1464 1465 // Return the loop body, which is the dominating block for the loop. 1466 Succ = BodyBlock; 1467 return BodyBlock; 1468} 1469 1470CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1471 // "continue" is a control-flow statement. Thus we stop processing the 1472 // current block. 1473 if (Block && !FinishBlock(Block)) 1474 return 0; 1475 1476 // Now create a new block that ends with the continue statement. 1477 Block = createBlock(false); 1478 Block->setTerminator(C); 1479 1480 // If there is no target for the continue, then we are looking at an 1481 // incomplete AST. This means the CFG cannot be constructed. 1482 if (ContinueTargetBlock) 1483 AddSuccessor(Block, ContinueTargetBlock); 1484 else 1485 badCFG = true; 1486 1487 return Block; 1488} 1489 1490CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1491 AddStmtChoice asc) { 1492 1493 if (asc.alwaysAdd()) { 1494 autoCreateBlock(); 1495 AppendStmt(Block, E); 1496 } 1497 1498 // VLA types have expressions that must be evaluated. 1499 if (E->isArgumentType()) { 1500 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1501 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1502 addStmt(VA->getSizeExpr()); 1503 } 1504 1505 return Block; 1506} 1507 1508/// VisitStmtExpr - Utility method to handle (nested) statement 1509/// expressions (a GCC extension). 1510CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1511 if (asc.alwaysAdd()) { 1512 autoCreateBlock(); 1513 AppendStmt(Block, SE); 1514 } 1515 return VisitCompoundStmt(SE->getSubStmt()); 1516} 1517 1518CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1519 // "switch" is a control-flow statement. Thus we stop processing the current 1520 // block. 1521 CFGBlock* SwitchSuccessor = NULL; 1522 1523 if (Block) { 1524 if (!FinishBlock(Block)) 1525 return 0; 1526 SwitchSuccessor = Block; 1527 } else SwitchSuccessor = Succ; 1528 1529 // Save the current "switch" context. 1530 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1531 save_break(BreakTargetBlock), 1532 save_default(DefaultCaseBlock); 1533 1534 // Set the "default" case to be the block after the switch statement. If the 1535 // switch statement contains a "default:", this value will be overwritten with 1536 // the block for that code. 1537 DefaultCaseBlock = SwitchSuccessor; 1538 1539 // Create a new block that will contain the switch statement. 1540 SwitchTerminatedBlock = createBlock(false); 1541 1542 // Now process the switch body. The code after the switch is the implicit 1543 // successor. 1544 Succ = SwitchSuccessor; 1545 BreakTargetBlock = SwitchSuccessor; 1546 1547 // When visiting the body, the case statements should automatically get linked 1548 // up to the switch. We also don't keep a pointer to the body, since all 1549 // control-flow from the switch goes to case/default statements. 1550 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1551 Block = NULL; 1552 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1553 if (Block) { 1554 if (!FinishBlock(BodyBlock)) 1555 return 0; 1556 } 1557 1558 // If we have no "default:" case, the default transition is to the code 1559 // following the switch body. 1560 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1561 1562 // Add the terminator and condition in the switch block. 1563 SwitchTerminatedBlock->setTerminator(Terminator); 1564 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1565 Block = SwitchTerminatedBlock; 1566 Block = addStmt(Terminator->getCond()); 1567 1568 // Finally, if the SwitchStmt contains a condition variable, add both the 1569 // SwitchStmt and the condition variable initialization to the CFG. 1570 if (VarDecl *VD = Terminator->getConditionVariable()) { 1571 if (Expr *Init = VD->getInit()) { 1572 autoCreateBlock(); 1573 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1574 addStmt(Init); 1575 } 1576 } 1577 1578 return Block; 1579} 1580 1581CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1582 // CaseStmts are essentially labels, so they are the first statement in a 1583 // block. 1584 1585 if (CS->getSubStmt()) 1586 addStmt(CS->getSubStmt()); 1587 1588 CFGBlock* CaseBlock = Block; 1589 if (!CaseBlock) 1590 CaseBlock = createBlock(); 1591 1592 // Cases statements partition blocks, so this is the top of the basic block we 1593 // were processing (the "case XXX:" is the label). 1594 CaseBlock->setLabel(CS); 1595 1596 if (!FinishBlock(CaseBlock)) 1597 return 0; 1598 1599 // Add this block to the list of successors for the block with the switch 1600 // statement. 1601 assert(SwitchTerminatedBlock); 1602 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1603 1604 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1605 Block = NULL; 1606 1607 // This block is now the implicit successor of other blocks. 1608 Succ = CaseBlock; 1609 1610 return CaseBlock; 1611} 1612 1613CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1614 if (Terminator->getSubStmt()) 1615 addStmt(Terminator->getSubStmt()); 1616 1617 DefaultCaseBlock = Block; 1618 1619 if (!DefaultCaseBlock) 1620 DefaultCaseBlock = createBlock(); 1621 1622 // Default statements partition blocks, so this is the top of the basic block 1623 // we were processing (the "default:" is the label). 1624 DefaultCaseBlock->setLabel(Terminator); 1625 1626 if (!FinishBlock(DefaultCaseBlock)) 1627 return 0; 1628 1629 // Unlike case statements, we don't add the default block to the successors 1630 // for the switch statement immediately. This is done when we finish 1631 // processing the switch statement. This allows for the default case 1632 // (including a fall-through to the code after the switch statement) to always 1633 // be the last successor of a switch-terminated block. 1634 1635 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1636 Block = NULL; 1637 1638 // This block is now the implicit successor of other blocks. 1639 Succ = DefaultCaseBlock; 1640 1641 return DefaultCaseBlock; 1642} 1643 1644CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1645 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1646 // current block. 1647 CFGBlock* TrySuccessor = NULL; 1648 1649 if (Block) { 1650 if (!FinishBlock(Block)) 1651 return 0; 1652 TrySuccessor = Block; 1653 } else TrySuccessor = Succ; 1654 1655 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1656 1657 // Create a new block that will contain the try statement. 1658 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1659 // Add the terminator in the try block. 1660 NewTryTerminatedBlock->setTerminator(Terminator); 1661 1662 bool HasCatchAll = false; 1663 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1664 // The code after the try is the implicit successor. 1665 Succ = TrySuccessor; 1666 CXXCatchStmt *CS = Terminator->getHandler(h); 1667 if (CS->getExceptionDecl() == 0) { 1668 HasCatchAll = true; 1669 } 1670 Block = NULL; 1671 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1672 if (CatchBlock == 0) 1673 return 0; 1674 // Add this block to the list of successors for the block with the try 1675 // statement. 1676 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1677 } 1678 if (!HasCatchAll) { 1679 if (PrevTryTerminatedBlock) 1680 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1681 else 1682 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1683 } 1684 1685 // The code after the try is the implicit successor. 1686 Succ = TrySuccessor; 1687 1688 // Save the current "try" context. 1689 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1690 TryTerminatedBlock = NewTryTerminatedBlock; 1691 1692 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1693 Block = NULL; 1694 Block = addStmt(Terminator->getTryBlock()); 1695 return Block; 1696} 1697 1698CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1699 // CXXCatchStmt are treated like labels, so they are the first statement in a 1700 // block. 1701 1702 if (CS->getHandlerBlock()) 1703 addStmt(CS->getHandlerBlock()); 1704 1705 CFGBlock* CatchBlock = Block; 1706 if (!CatchBlock) 1707 CatchBlock = createBlock(); 1708 1709 CatchBlock->setLabel(CS); 1710 1711 if (!FinishBlock(CatchBlock)) 1712 return 0; 1713 1714 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1715 Block = NULL; 1716 1717 return CatchBlock; 1718} 1719 1720CFGBlock *CFGBuilder::VisitCXXMemberCallExpr(CXXMemberCallExpr *C, 1721 AddStmtChoice asc) { 1722 AddStmtChoice::Kind K = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 1723 : AddStmtChoice::AlwaysAdd; 1724 autoCreateBlock(); 1725 AppendStmt(Block, C, AddStmtChoice(K)); 1726 return VisitChildren(C); 1727} 1728 1729CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1730 // Lazily create the indirect-goto dispatch block if there isn't one already. 1731 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1732 1733 if (!IBlock) { 1734 IBlock = createBlock(false); 1735 cfg->setIndirectGotoBlock(IBlock); 1736 } 1737 1738 // IndirectGoto is a control-flow statement. Thus we stop processing the 1739 // current block and create a new one. 1740 if (Block && !FinishBlock(Block)) 1741 return 0; 1742 1743 Block = createBlock(false); 1744 Block->setTerminator(I); 1745 AddSuccessor(Block, IBlock); 1746 return addStmt(I->getTarget()); 1747} 1748 1749} // end anonymous namespace 1750 1751/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1752/// no successors or predecessors. If this is the first block created in the 1753/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1754CFGBlock* CFG::createBlock() { 1755 bool first_block = begin() == end(); 1756 1757 // Create the block. 1758 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1759 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1760 Blocks.push_back(Mem, BlkBVC); 1761 1762 // If this is the first block, set it as the Entry and Exit. 1763 if (first_block) 1764 Entry = Exit = &back(); 1765 1766 // Return the block. 1767 return &back(); 1768} 1769 1770/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1771/// CFG is returned to the caller. 1772CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1773 bool AddEHEdges, bool AddScopes) { 1774 CFGBuilder Builder; 1775 return Builder.buildCFG(D, Statement, C, AddEHEdges, AddScopes); 1776} 1777 1778//===----------------------------------------------------------------------===// 1779// CFG: Queries for BlkExprs. 1780//===----------------------------------------------------------------------===// 1781 1782namespace { 1783 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1784} 1785 1786static void FindSubExprAssignments(Stmt *S, 1787 llvm::SmallPtrSet<Expr*,50>& Set) { 1788 if (!S) 1789 return; 1790 1791 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1792 Stmt *child = *I; 1793 if (!child) 1794 continue; 1795 1796 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1797 if (B->isAssignmentOp()) Set.insert(B); 1798 1799 FindSubExprAssignments(child, Set); 1800 } 1801} 1802 1803static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1804 BlkExprMapTy* M = new BlkExprMapTy(); 1805 1806 // Look for assignments that are used as subexpressions. These are the only 1807 // assignments that we want to *possibly* register as a block-level 1808 // expression. Basically, if an assignment occurs both in a subexpression and 1809 // at the block-level, it is a block-level expression. 1810 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1811 1812 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1813 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1814 FindSubExprAssignments(*BI, SubExprAssignments); 1815 1816 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1817 1818 // Iterate over the statements again on identify the Expr* and Stmt* at the 1819 // block-level that are block-level expressions. 1820 1821 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1822 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1823 1824 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1825 // Assignment expressions that are not nested within another 1826 // expression are really "statements" whose value is never used by 1827 // another expression. 1828 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1829 continue; 1830 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1831 // Special handling for statement expressions. The last statement in 1832 // the statement expression is also a block-level expr. 1833 const CompoundStmt* C = Terminator->getSubStmt(); 1834 if (!C->body_empty()) { 1835 unsigned x = M->size(); 1836 (*M)[C->body_back()] = x; 1837 } 1838 } 1839 1840 unsigned x = M->size(); 1841 (*M)[Exp] = x; 1842 } 1843 1844 // Look at terminators. The condition is a block-level expression. 1845 1846 Stmt* S = (*I)->getTerminatorCondition(); 1847 1848 if (S && M->find(S) == M->end()) { 1849 unsigned x = M->size(); 1850 (*M)[S] = x; 1851 } 1852 } 1853 1854 return M; 1855} 1856 1857CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1858 assert(S != NULL); 1859 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1860 1861 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1862 BlkExprMapTy::iterator I = M->find(S); 1863 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1864} 1865 1866unsigned CFG::getNumBlkExprs() { 1867 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1868 return M->size(); 1869 else { 1870 // We assume callers interested in the number of BlkExprs will want 1871 // the map constructed if it doesn't already exist. 1872 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1873 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1874 } 1875} 1876 1877//===----------------------------------------------------------------------===// 1878// Cleanup: CFG dstor. 1879//===----------------------------------------------------------------------===// 1880 1881CFG::~CFG() { 1882 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1883} 1884 1885//===----------------------------------------------------------------------===// 1886// CFG pretty printing 1887//===----------------------------------------------------------------------===// 1888 1889namespace { 1890 1891class StmtPrinterHelper : public PrinterHelper { 1892 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1893 StmtMapTy StmtMap; 1894 signed CurrentBlock; 1895 unsigned CurrentStmt; 1896 const LangOptions &LangOpts; 1897public: 1898 1899 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1900 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1901 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1902 unsigned j = 1; 1903 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1904 BI != BEnd; ++BI, ++j ) 1905 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1906 } 1907 } 1908 1909 virtual ~StmtPrinterHelper() {} 1910 1911 const LangOptions &getLangOpts() const { return LangOpts; } 1912 void setBlockID(signed i) { CurrentBlock = i; } 1913 void setStmtID(unsigned i) { CurrentStmt = i; } 1914 1915 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1916 1917 StmtMapTy::iterator I = StmtMap.find(Terminator); 1918 1919 if (I == StmtMap.end()) 1920 return false; 1921 1922 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 1923 && I->second.second == CurrentStmt) { 1924 return false; 1925 } 1926 1927 OS << "[B" << I->second.first << "." << I->second.second << "]"; 1928 return true; 1929 } 1930}; 1931} // end anonymous namespace 1932 1933 1934namespace { 1935class CFGBlockTerminatorPrint 1936 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 1937 1938 llvm::raw_ostream& OS; 1939 StmtPrinterHelper* Helper; 1940 PrintingPolicy Policy; 1941public: 1942 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 1943 const PrintingPolicy &Policy) 1944 : OS(os), Helper(helper), Policy(Policy) {} 1945 1946 void VisitIfStmt(IfStmt* I) { 1947 OS << "if "; 1948 I->getCond()->printPretty(OS,Helper,Policy); 1949 } 1950 1951 // Default case. 1952 void VisitStmt(Stmt* Terminator) { 1953 Terminator->printPretty(OS, Helper, Policy); 1954 } 1955 1956 void VisitForStmt(ForStmt* F) { 1957 OS << "for (" ; 1958 if (F->getInit()) 1959 OS << "..."; 1960 OS << "; "; 1961 if (Stmt* C = F->getCond()) 1962 C->printPretty(OS, Helper, Policy); 1963 OS << "; "; 1964 if (F->getInc()) 1965 OS << "..."; 1966 OS << ")"; 1967 } 1968 1969 void VisitWhileStmt(WhileStmt* W) { 1970 OS << "while " ; 1971 if (Stmt* C = W->getCond()) 1972 C->printPretty(OS, Helper, Policy); 1973 } 1974 1975 void VisitDoStmt(DoStmt* D) { 1976 OS << "do ... while "; 1977 if (Stmt* C = D->getCond()) 1978 C->printPretty(OS, Helper, Policy); 1979 } 1980 1981 void VisitSwitchStmt(SwitchStmt* Terminator) { 1982 OS << "switch "; 1983 Terminator->getCond()->printPretty(OS, Helper, Policy); 1984 } 1985 1986 void VisitCXXTryStmt(CXXTryStmt* CS) { 1987 OS << "try ..."; 1988 } 1989 1990 void VisitConditionalOperator(ConditionalOperator* C) { 1991 C->getCond()->printPretty(OS, Helper, Policy); 1992 OS << " ? ... : ..."; 1993 } 1994 1995 void VisitChooseExpr(ChooseExpr* C) { 1996 OS << "__builtin_choose_expr( "; 1997 C->getCond()->printPretty(OS, Helper, Policy); 1998 OS << " )"; 1999 } 2000 2001 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 2002 OS << "goto *"; 2003 I->getTarget()->printPretty(OS, Helper, Policy); 2004 } 2005 2006 void VisitBinaryOperator(BinaryOperator* B) { 2007 if (!B->isLogicalOp()) { 2008 VisitExpr(B); 2009 return; 2010 } 2011 2012 B->getLHS()->printPretty(OS, Helper, Policy); 2013 2014 switch (B->getOpcode()) { 2015 case BinaryOperator::LOr: 2016 OS << " || ..."; 2017 return; 2018 case BinaryOperator::LAnd: 2019 OS << " && ..."; 2020 return; 2021 default: 2022 assert(false && "Invalid logical operator."); 2023 } 2024 } 2025 2026 void VisitExpr(Expr* E) { 2027 E->printPretty(OS, Helper, Policy); 2028 } 2029}; 2030} // end anonymous namespace 2031 2032 2033static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2034 const CFGElement &E) { 2035 Stmt *Terminator = E; 2036 2037 if (E.asStartScope()) { 2038 OS << "start scope\n"; 2039 return; 2040 } 2041 if (E.asEndScope()) { 2042 OS << "end scope\n"; 2043 return; 2044 } 2045 2046 if (Helper) { 2047 // special printing for statement-expressions. 2048 if (StmtExpr* SE = dyn_cast<StmtExpr>(Terminator)) { 2049 CompoundStmt* Sub = SE->getSubStmt(); 2050 2051 if (Sub->child_begin() != Sub->child_end()) { 2052 OS << "({ ... ; "; 2053 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2054 OS << " })\n"; 2055 return; 2056 } 2057 } 2058 2059 // special printing for comma expressions. 2060 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Terminator)) { 2061 if (B->getOpcode() == BinaryOperator::Comma) { 2062 OS << "... , "; 2063 Helper->handledStmt(B->getRHS(),OS); 2064 OS << '\n'; 2065 return; 2066 } 2067 } 2068 } 2069 2070 Terminator->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2071 2072 // Expressions need a newline. 2073 if (isa<Expr>(Terminator)) OS << '\n'; 2074} 2075 2076static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2077 const CFGBlock& B, 2078 StmtPrinterHelper* Helper, bool print_edges) { 2079 2080 if (Helper) Helper->setBlockID(B.getBlockID()); 2081 2082 // Print the header. 2083 OS << "\n [ B" << B.getBlockID(); 2084 2085 if (&B == &cfg->getEntry()) 2086 OS << " (ENTRY) ]\n"; 2087 else if (&B == &cfg->getExit()) 2088 OS << " (EXIT) ]\n"; 2089 else if (&B == cfg->getIndirectGotoBlock()) 2090 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2091 else 2092 OS << " ]\n"; 2093 2094 // Print the label of this block. 2095 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2096 2097 if (print_edges) 2098 OS << " "; 2099 2100 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2101 OS << L->getName(); 2102 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2103 OS << "case "; 2104 C->getLHS()->printPretty(OS, Helper, 2105 PrintingPolicy(Helper->getLangOpts())); 2106 if (C->getRHS()) { 2107 OS << " ... "; 2108 C->getRHS()->printPretty(OS, Helper, 2109 PrintingPolicy(Helper->getLangOpts())); 2110 } 2111 } else if (isa<DefaultStmt>(Label)) 2112 OS << "default"; 2113 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2114 OS << "catch ("; 2115 if (CS->getExceptionDecl()) 2116 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2117 0); 2118 else 2119 OS << "..."; 2120 OS << ")"; 2121 2122 } else 2123 assert(false && "Invalid label statement in CFGBlock."); 2124 2125 OS << ":\n"; 2126 } 2127 2128 // Iterate through the statements in the block and print them. 2129 unsigned j = 1; 2130 2131 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2132 I != E ; ++I, ++j ) { 2133 2134 // Print the statement # in the basic block and the statement itself. 2135 if (print_edges) 2136 OS << " "; 2137 2138 OS << llvm::format("%3d", j) << ": "; 2139 2140 if (Helper) 2141 Helper->setStmtID(j); 2142 2143 print_stmt(OS,Helper,*I); 2144 } 2145 2146 // Print the terminator of this block. 2147 if (B.getTerminator()) { 2148 if (print_edges) 2149 OS << " "; 2150 2151 OS << " T: "; 2152 2153 if (Helper) Helper->setBlockID(-1); 2154 2155 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2156 PrintingPolicy(Helper->getLangOpts())); 2157 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2158 OS << '\n'; 2159 } 2160 2161 if (print_edges) { 2162 // Print the predecessors of this block. 2163 OS << " Predecessors (" << B.pred_size() << "):"; 2164 unsigned i = 0; 2165 2166 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2167 I != E; ++I, ++i) { 2168 2169 if (i == 8 || (i-8) == 0) 2170 OS << "\n "; 2171 2172 OS << " B" << (*I)->getBlockID(); 2173 } 2174 2175 OS << '\n'; 2176 2177 // Print the successors of this block. 2178 OS << " Successors (" << B.succ_size() << "):"; 2179 i = 0; 2180 2181 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2182 I != E; ++I, ++i) { 2183 2184 if (i == 8 || (i-8) % 10 == 0) 2185 OS << "\n "; 2186 2187 if (*I) 2188 OS << " B" << (*I)->getBlockID(); 2189 else 2190 OS << " NULL"; 2191 } 2192 2193 OS << '\n'; 2194 } 2195} 2196 2197 2198/// dump - A simple pretty printer of a CFG that outputs to stderr. 2199void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2200 2201/// print - A simple pretty printer of a CFG that outputs to an ostream. 2202void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2203 StmtPrinterHelper Helper(this, LO); 2204 2205 // Print the entry block. 2206 print_block(OS, this, getEntry(), &Helper, true); 2207 2208 // Iterate through the CFGBlocks and print them one by one. 2209 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2210 // Skip the entry block, because we already printed it. 2211 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2212 continue; 2213 2214 print_block(OS, this, **I, &Helper, true); 2215 } 2216 2217 // Print the exit block. 2218 print_block(OS, this, getExit(), &Helper, true); 2219 OS.flush(); 2220} 2221 2222/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2223void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2224 print(llvm::errs(), cfg, LO); 2225} 2226 2227/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2228/// Generally this will only be called from CFG::print. 2229void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2230 const LangOptions &LO) const { 2231 StmtPrinterHelper Helper(cfg, LO); 2232 print_block(OS, cfg, *this, &Helper, true); 2233} 2234 2235/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2236void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2237 const LangOptions &LO) const { 2238 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2239 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2240} 2241 2242Stmt* CFGBlock::getTerminatorCondition() { 2243 2244 if (!Terminator) 2245 return NULL; 2246 2247 Expr* E = NULL; 2248 2249 switch (Terminator->getStmtClass()) { 2250 default: 2251 break; 2252 2253 case Stmt::ForStmtClass: 2254 E = cast<ForStmt>(Terminator)->getCond(); 2255 break; 2256 2257 case Stmt::WhileStmtClass: 2258 E = cast<WhileStmt>(Terminator)->getCond(); 2259 break; 2260 2261 case Stmt::DoStmtClass: 2262 E = cast<DoStmt>(Terminator)->getCond(); 2263 break; 2264 2265 case Stmt::IfStmtClass: 2266 E = cast<IfStmt>(Terminator)->getCond(); 2267 break; 2268 2269 case Stmt::ChooseExprClass: 2270 E = cast<ChooseExpr>(Terminator)->getCond(); 2271 break; 2272 2273 case Stmt::IndirectGotoStmtClass: 2274 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2275 break; 2276 2277 case Stmt::SwitchStmtClass: 2278 E = cast<SwitchStmt>(Terminator)->getCond(); 2279 break; 2280 2281 case Stmt::ConditionalOperatorClass: 2282 E = cast<ConditionalOperator>(Terminator)->getCond(); 2283 break; 2284 2285 case Stmt::BinaryOperatorClass: // '&&' and '||' 2286 E = cast<BinaryOperator>(Terminator)->getLHS(); 2287 break; 2288 2289 case Stmt::ObjCForCollectionStmtClass: 2290 return Terminator; 2291 } 2292 2293 return E ? E->IgnoreParens() : NULL; 2294} 2295 2296bool CFGBlock::hasBinaryBranchTerminator() const { 2297 2298 if (!Terminator) 2299 return false; 2300 2301 Expr* E = NULL; 2302 2303 switch (Terminator->getStmtClass()) { 2304 default: 2305 return false; 2306 2307 case Stmt::ForStmtClass: 2308 case Stmt::WhileStmtClass: 2309 case Stmt::DoStmtClass: 2310 case Stmt::IfStmtClass: 2311 case Stmt::ChooseExprClass: 2312 case Stmt::ConditionalOperatorClass: 2313 case Stmt::BinaryOperatorClass: 2314 return true; 2315 } 2316 2317 return E ? E->IgnoreParens() : NULL; 2318} 2319 2320 2321//===----------------------------------------------------------------------===// 2322// CFG Graphviz Visualization 2323//===----------------------------------------------------------------------===// 2324 2325 2326#ifndef NDEBUG 2327static StmtPrinterHelper* GraphHelper; 2328#endif 2329 2330void CFG::viewCFG(const LangOptions &LO) const { 2331#ifndef NDEBUG 2332 StmtPrinterHelper H(this, LO); 2333 GraphHelper = &H; 2334 llvm::ViewGraph(this,"CFG"); 2335 GraphHelper = NULL; 2336#endif 2337} 2338 2339namespace llvm { 2340template<> 2341struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2342 2343 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2344 2345 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2346 2347#ifndef NDEBUG 2348 std::string OutSStr; 2349 llvm::raw_string_ostream Out(OutSStr); 2350 print_block(Out,Graph, *Node, GraphHelper, false); 2351 std::string& OutStr = Out.str(); 2352 2353 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2354 2355 // Process string output to make it nicer... 2356 for (unsigned i = 0; i != OutStr.length(); ++i) 2357 if (OutStr[i] == '\n') { // Left justify 2358 OutStr[i] = '\\'; 2359 OutStr.insert(OutStr.begin()+i+1, 'l'); 2360 } 2361 2362 return OutStr; 2363#else 2364 return ""; 2365#endif 2366 } 2367}; 2368} // end namespace llvm 2369