CFG.cpp revision fc61d94fbdbcd2b423976e21f24d423fcd442486
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 if (!S) { 342 badCFG = true; 343 return 0; 344 } 345 switch (S->getStmtClass()) { 346 default: 347 return VisitStmt(S, asc); 348 349 case Stmt::AddrLabelExprClass: 350 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 351 352 case Stmt::BinaryOperatorClass: 353 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 354 355 case Stmt::BlockExprClass: 356 return VisitBlockExpr(cast<BlockExpr>(S), asc); 357 358 case Stmt::BreakStmtClass: 359 return VisitBreakStmt(cast<BreakStmt>(S)); 360 361 case Stmt::CallExprClass: 362 return VisitCallExpr(cast<CallExpr>(S), asc); 363 364 case Stmt::CaseStmtClass: 365 return VisitCaseStmt(cast<CaseStmt>(S)); 366 367 case Stmt::ChooseExprClass: 368 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 369 370 case Stmt::CompoundStmtClass: 371 return VisitCompoundStmt(cast<CompoundStmt>(S)); 372 373 case Stmt::ConditionalOperatorClass: 374 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 375 376 case Stmt::ContinueStmtClass: 377 return VisitContinueStmt(cast<ContinueStmt>(S)); 378 379 case Stmt::CXXCatchStmtClass: 380 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 381 382 case Stmt::CXXMemberCallExprClass: 383 return VisitCXXMemberCallExpr(cast<CXXMemberCallExpr>(S), asc); 384 385 case Stmt::CXXThrowExprClass: 386 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 387 388 case Stmt::CXXTryStmtClass: 389 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 390 391 case Stmt::DeclStmtClass: 392 return VisitDeclStmt(cast<DeclStmt>(S)); 393 394 case Stmt::DefaultStmtClass: 395 return VisitDefaultStmt(cast<DefaultStmt>(S)); 396 397 case Stmt::DoStmtClass: 398 return VisitDoStmt(cast<DoStmt>(S)); 399 400 case Stmt::ForStmtClass: 401 return VisitForStmt(cast<ForStmt>(S)); 402 403 case Stmt::GotoStmtClass: 404 return VisitGotoStmt(cast<GotoStmt>(S)); 405 406 case Stmt::IfStmtClass: 407 return VisitIfStmt(cast<IfStmt>(S)); 408 409 case Stmt::IndirectGotoStmtClass: 410 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 411 412 case Stmt::LabelStmtClass: 413 return VisitLabelStmt(cast<LabelStmt>(S)); 414 415 case Stmt::MemberExprClass: 416 return VisitMemberExpr(cast<MemberExpr>(S), asc); 417 418 case Stmt::ObjCAtCatchStmtClass: 419 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 420 421 case Stmt::ObjCAtSynchronizedStmtClass: 422 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 423 424 case Stmt::ObjCAtThrowStmtClass: 425 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 426 427 case Stmt::ObjCAtTryStmtClass: 428 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 429 430 case Stmt::ObjCForCollectionStmtClass: 431 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 432 433 case Stmt::ParenExprClass: 434 S = cast<ParenExpr>(S)->getSubExpr(); 435 goto tryAgain; 436 437 case Stmt::NullStmtClass: 438 return Block; 439 440 case Stmt::ReturnStmtClass: 441 return VisitReturnStmt(cast<ReturnStmt>(S)); 442 443 case Stmt::SizeOfAlignOfExprClass: 444 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 445 446 case Stmt::StmtExprClass: 447 return VisitStmtExpr(cast<StmtExpr>(S), asc); 448 449 case Stmt::SwitchStmtClass: 450 return VisitSwitchStmt(cast<SwitchStmt>(S)); 451 452 case Stmt::WhileStmtClass: 453 return VisitWhileStmt(cast<WhileStmt>(S)); 454 } 455} 456 457CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 458 if (asc.alwaysAdd()) { 459 autoCreateBlock(); 460 AppendStmt(Block, S, asc); 461 } 462 463 return VisitChildren(S); 464} 465 466/// VisitChildren - Visit the children of a Stmt. 467CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 468 CFGBlock *B = Block; 469 for (Stmt::child_iterator I = Terminator->child_begin(), 470 E = Terminator->child_end(); I != E; ++I) { 471 if (*I) B = Visit(*I); 472 } 473 return B; 474} 475 476CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 477 AddStmtChoice asc) { 478 AddressTakenLabels.insert(A->getLabel()); 479 480 if (asc.alwaysAdd()) { 481 autoCreateBlock(); 482 AppendStmt(Block, A, asc); 483 } 484 485 return Block; 486} 487 488CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 489 AddStmtChoice asc) { 490 if (B->isLogicalOp()) { // && or || 491 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 492 AppendStmt(ConfluenceBlock, B, asc); 493 494 if (!FinishBlock(ConfluenceBlock)) 495 return 0; 496 497 // create the block evaluating the LHS 498 CFGBlock* LHSBlock = createBlock(false); 499 LHSBlock->setTerminator(B); 500 501 // create the block evaluating the RHS 502 Succ = ConfluenceBlock; 503 Block = NULL; 504 CFGBlock* RHSBlock = addStmt(B->getRHS()); 505 506 if (RHSBlock) { 507 if (!FinishBlock(RHSBlock)) 508 return 0; 509 } 510 else { 511 // Create an empty block for cases where the RHS doesn't require 512 // any explicit statements in the CFG. 513 RHSBlock = createBlock(); 514 } 515 516 // See if this is a known constant. 517 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 518 if (KnownVal.isKnown() && (B->getOpcode() == BinaryOperator::LOr)) 519 KnownVal.negate(); 520 521 // Now link the LHSBlock with RHSBlock. 522 if (B->getOpcode() == BinaryOperator::LOr) { 523 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 524 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 525 } else { 526 assert(B->getOpcode() == BinaryOperator::LAnd); 527 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 528 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 529 } 530 531 // Generate the blocks for evaluating the LHS. 532 Block = LHSBlock; 533 return addStmt(B->getLHS()); 534 } 535 else if (B->getOpcode() == BinaryOperator::Comma) { // , 536 autoCreateBlock(); 537 AppendStmt(Block, B, asc); 538 addStmt(B->getRHS()); 539 return addStmt(B->getLHS()); 540 } 541 else if (B->isAssignmentOp()) { 542 if (asc.alwaysAdd()) { 543 autoCreateBlock(); 544 AppendStmt(Block, B, asc); 545 } 546 547 Visit(B->getRHS()); 548 return Visit(B->getLHS(), AddStmtChoice::AsLValueNotAlwaysAdd); 549 } 550 551 return VisitStmt(B, asc); 552} 553 554CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 555 if (asc.alwaysAdd()) { 556 autoCreateBlock(); 557 AppendStmt(Block, E, asc); 558 } 559 return Block; 560} 561 562CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 563 // "break" is a control-flow statement. Thus we stop processing the current 564 // block. 565 if (Block && !FinishBlock(Block)) 566 return 0; 567 568 // Now create a new block that ends with the break statement. 569 Block = createBlock(false); 570 Block->setTerminator(B); 571 572 // If there is no target for the break, then we are looking at an incomplete 573 // AST. This means that the CFG cannot be constructed. 574 if (BreakTargetBlock) 575 AddSuccessor(Block, BreakTargetBlock); 576 else 577 badCFG = true; 578 579 580 return Block; 581} 582 583static bool CanThrow(Expr *E) { 584 QualType Ty = E->getType(); 585 if (Ty->isFunctionPointerType()) 586 Ty = Ty->getAs<PointerType>()->getPointeeType(); 587 else if (Ty->isBlockPointerType()) 588 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 589 590 const FunctionType *FT = Ty->getAs<FunctionType>(); 591 if (FT) { 592 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 593 if (Proto->hasEmptyExceptionSpec()) 594 return false; 595 } 596 return true; 597} 598 599CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 600 // If this is a call to a no-return function, this stops the block here. 601 bool NoReturn = false; 602 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 603 NoReturn = true; 604 } 605 606 bool AddEHEdge = false; 607 608 // Languages without exceptions are assumed to not throw. 609 if (Context->getLangOptions().Exceptions) { 610 if (AddEHEdges) 611 AddEHEdge = true; 612 } 613 614 if (FunctionDecl *FD = C->getDirectCallee()) { 615 if (FD->hasAttr<NoReturnAttr>()) 616 NoReturn = true; 617 if (FD->hasAttr<NoThrowAttr>()) 618 AddEHEdge = false; 619 } 620 621 if (!CanThrow(C->getCallee())) 622 AddEHEdge = false; 623 624 if (!NoReturn && !AddEHEdge) { 625 if (asc.asLValue()) 626 return VisitStmt(C, AddStmtChoice::AlwaysAddAsLValue); 627 else 628 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 629 } 630 631 if (Block) { 632 Succ = Block; 633 if (!FinishBlock(Block)) 634 return 0; 635 } 636 637 Block = createBlock(!NoReturn); 638 AppendStmt(Block, C, asc); 639 640 if (NoReturn) { 641 // Wire this to the exit block directly. 642 AddSuccessor(Block, &cfg->getExit()); 643 } 644 if (AddEHEdge) { 645 // Add exceptional edges. 646 if (TryTerminatedBlock) 647 AddSuccessor(Block, TryTerminatedBlock); 648 else 649 AddSuccessor(Block, &cfg->getExit()); 650 } 651 652 return VisitChildren(C); 653} 654 655CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 656 AddStmtChoice asc) { 657 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 658 AppendStmt(ConfluenceBlock, C, asc); 659 if (!FinishBlock(ConfluenceBlock)) 660 return 0; 661 662 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 663 : AddStmtChoice::AlwaysAdd; 664 665 Succ = ConfluenceBlock; 666 Block = NULL; 667 CFGBlock* LHSBlock = addStmt(C->getLHS(), asc); 668 if (!FinishBlock(LHSBlock)) 669 return 0; 670 671 Succ = ConfluenceBlock; 672 Block = NULL; 673 CFGBlock* RHSBlock = addStmt(C->getRHS(), asc); 674 if (!FinishBlock(RHSBlock)) 675 return 0; 676 677 Block = createBlock(false); 678 // See if this is a known constant. 679 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 680 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 681 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 682 Block->setTerminator(C); 683 return addStmt(C->getCond()); 684} 685 686 687CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 688 EndScope(C); 689 690 CFGBlock* LastBlock = Block; 691 692 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 693 I != E; ++I ) { 694 LastBlock = addStmt(*I); 695 696 if (badCFG) 697 return NULL; 698 } 699 700 LastBlock = StartScope(C, LastBlock); 701 702 return LastBlock; 703} 704 705CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 706 AddStmtChoice asc) { 707 // Create the confluence block that will "merge" the results of the ternary 708 // expression. 709 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 710 AppendStmt(ConfluenceBlock, C, asc); 711 if (!FinishBlock(ConfluenceBlock)) 712 return 0; 713 714 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 715 : AddStmtChoice::AlwaysAdd; 716 717 // Create a block for the LHS expression if there is an LHS expression. A 718 // GCC extension allows LHS to be NULL, causing the condition to be the 719 // value that is returned instead. 720 // e.g: x ?: y is shorthand for: x ? x : y; 721 Succ = ConfluenceBlock; 722 Block = NULL; 723 CFGBlock* LHSBlock = NULL; 724 if (C->getLHS()) { 725 LHSBlock = addStmt(C->getLHS(), asc); 726 if (!FinishBlock(LHSBlock)) 727 return 0; 728 Block = NULL; 729 } 730 731 // Create the block for the RHS expression. 732 Succ = ConfluenceBlock; 733 CFGBlock* RHSBlock = addStmt(C->getRHS(), asc); 734 if (!FinishBlock(RHSBlock)) 735 return 0; 736 737 // Create the block that will contain the condition. 738 Block = createBlock(false); 739 740 // See if this is a known constant. 741 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 742 if (LHSBlock) { 743 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 744 } else { 745 if (KnownVal.isFalse()) { 746 // If we know the condition is false, add NULL as the successor for 747 // the block containing the condition. In this case, the confluence 748 // block will have just one predecessor. 749 AddSuccessor(Block, 0); 750 assert(ConfluenceBlock->pred_size() == 1); 751 } else { 752 // If we have no LHS expression, add the ConfluenceBlock as a direct 753 // successor for the block containing the condition. Moreover, we need to 754 // reverse the order of the predecessors in the ConfluenceBlock because 755 // the RHSBlock will have been added to the succcessors already, and we 756 // want the first predecessor to the the block containing the expression 757 // for the case when the ternary expression evaluates to true. 758 AddSuccessor(Block, ConfluenceBlock); 759 assert(ConfluenceBlock->pred_size() == 2); 760 std::reverse(ConfluenceBlock->pred_begin(), 761 ConfluenceBlock->pred_end()); 762 } 763 } 764 765 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 766 Block->setTerminator(C); 767 return addStmt(C->getCond()); 768} 769 770CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 771 autoCreateBlock(); 772 773 if (DS->isSingleDecl()) { 774 AppendStmt(Block, DS); 775 return VisitDeclSubExpr(DS->getSingleDecl()); 776 } 777 778 CFGBlock *B = 0; 779 780 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 781 typedef llvm::SmallVector<Decl*,10> BufTy; 782 BufTy Buf(DS->decl_begin(), DS->decl_end()); 783 784 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 785 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 786 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 787 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 788 789 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 790 // automatically freed with the CFG. 791 DeclGroupRef DG(*I); 792 Decl *D = *I; 793 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 794 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 795 796 // Append the fake DeclStmt to block. 797 AppendStmt(Block, DSNew); 798 B = VisitDeclSubExpr(D); 799 } 800 801 return B; 802} 803 804/// VisitDeclSubExpr - Utility method to add block-level expressions for 805/// initializers in Decls. 806CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 807 assert(Block); 808 809 VarDecl *VD = dyn_cast<VarDecl>(D); 810 811 if (!VD) 812 return Block; 813 814 Expr *Init = VD->getInit(); 815 816 if (Init) { 817 AddStmtChoice::Kind k = 818 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 819 : AddStmtChoice::NotAlwaysAdd; 820 Visit(Init, AddStmtChoice(k)); 821 } 822 823 // If the type of VD is a VLA, then we must process its size expressions. 824 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 825 VA = FindVA(VA->getElementType().getTypePtr())) 826 Block = addStmt(VA->getSizeExpr()); 827 828 return Block; 829} 830 831CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 832 // We may see an if statement in the middle of a basic block, or it may be the 833 // first statement we are processing. In either case, we create a new basic 834 // block. First, we create the blocks for the then...else statements, and 835 // then we create the block containing the if statement. If we were in the 836 // middle of a block, we stop processing that block. That block is then the 837 // implicit successor for the "then" and "else" clauses. 838 839 // The block we were proccessing is now finished. Make it the successor 840 // block. 841 if (Block) { 842 Succ = Block; 843 if (!FinishBlock(Block)) 844 return 0; 845 } 846 847 // Process the false branch. 848 CFGBlock* ElseBlock = Succ; 849 850 if (Stmt* Else = I->getElse()) { 851 SaveAndRestore<CFGBlock*> sv(Succ); 852 853 // NULL out Block so that the recursive call to Visit will 854 // create a new basic block. 855 Block = NULL; 856 ElseBlock = addStmt(Else); 857 858 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 859 ElseBlock = sv.get(); 860 else if (Block) { 861 if (!FinishBlock(ElseBlock)) 862 return 0; 863 } 864 } 865 866 // Process the true branch. 867 CFGBlock* ThenBlock; 868 { 869 Stmt* Then = I->getThen(); 870 assert(Then); 871 SaveAndRestore<CFGBlock*> sv(Succ); 872 Block = NULL; 873 ThenBlock = addStmt(Then); 874 875 if (!ThenBlock) { 876 // We can reach here if the "then" body has all NullStmts. 877 // Create an empty block so we can distinguish between true and false 878 // branches in path-sensitive analyses. 879 ThenBlock = createBlock(false); 880 AddSuccessor(ThenBlock, sv.get()); 881 } else if (Block) { 882 if (!FinishBlock(ThenBlock)) 883 return 0; 884 } 885 } 886 887 // Now create a new block containing the if statement. 888 Block = createBlock(false); 889 890 // Set the terminator of the new block to the If statement. 891 Block->setTerminator(I); 892 893 // See if this is a known constant. 894 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 895 896 // Now add the successors. 897 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 898 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 899 900 // Add the condition as the last statement in the new block. This may create 901 // new blocks as the condition may contain control-flow. Any newly created 902 // blocks will be pointed to be "Block". 903 Block = addStmt(I->getCond()); 904 905 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 906 // and the condition variable initialization to the CFG. 907 if (VarDecl *VD = I->getConditionVariable()) { 908 if (Expr *Init = VD->getInit()) { 909 autoCreateBlock(); 910 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 911 addStmt(Init); 912 } 913 } 914 915 return Block; 916} 917 918 919CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 920 // If we were in the middle of a block we stop processing that block. 921 // 922 // NOTE: If a "return" appears in the middle of a block, this means that the 923 // code afterwards is DEAD (unreachable). We still keep a basic block 924 // for that code; a simple "mark-and-sweep" from the entry block will be 925 // able to report such dead blocks. 926 if (Block) 927 FinishBlock(Block); 928 929 // Create the new block. 930 Block = createBlock(false); 931 932 // The Exit block is the only successor. 933 AddSuccessor(Block, &cfg->getExit()); 934 935 // Add the return statement to the block. This may create new blocks if R 936 // contains control-flow (short-circuit operations). 937 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 938} 939 940CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 941 // Get the block of the labeled statement. Add it to our map. 942 addStmt(L->getSubStmt()); 943 CFGBlock* LabelBlock = Block; 944 945 if (!LabelBlock) // This can happen when the body is empty, i.e. 946 LabelBlock = createBlock(); // scopes that only contains NullStmts. 947 948 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 949 LabelMap[ L ] = LabelBlock; 950 951 // Labels partition blocks, so this is the end of the basic block we were 952 // processing (L is the block's label). Because this is label (and we have 953 // already processed the substatement) there is no extra control-flow to worry 954 // about. 955 LabelBlock->setLabel(L); 956 if (!FinishBlock(LabelBlock)) 957 return 0; 958 959 // We set Block to NULL to allow lazy creation of a new block (if necessary); 960 Block = NULL; 961 962 // This block is now the implicit successor of other blocks. 963 Succ = LabelBlock; 964 965 return LabelBlock; 966} 967 968CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 969 // Goto is a control-flow statement. Thus we stop processing the current 970 // block and create a new one. 971 if (Block) 972 FinishBlock(Block); 973 974 Block = createBlock(false); 975 Block->setTerminator(G); 976 977 // If we already know the mapping to the label block add the successor now. 978 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 979 980 if (I == LabelMap.end()) 981 // We will need to backpatch this block later. 982 BackpatchBlocks.push_back(Block); 983 else 984 AddSuccessor(Block, I->second); 985 986 return Block; 987} 988 989CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 990 CFGBlock* LoopSuccessor = NULL; 991 992 // "for" is a control-flow statement. Thus we stop processing the current 993 // block. 994 if (Block) { 995 if (!FinishBlock(Block)) 996 return 0; 997 LoopSuccessor = Block; 998 } else 999 LoopSuccessor = Succ; 1000 1001 // Save the current value for the break targets. 1002 // All breaks should go to the code following the loop. 1003 SaveAndRestore<CFGBlock*> save_break(BreakTargetBlock); 1004 BreakTargetBlock = LoopSuccessor; 1005 1006 // Because of short-circuit evaluation, the condition of the loop can span 1007 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1008 // evaluate the condition. 1009 CFGBlock* ExitConditionBlock = createBlock(false); 1010 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1011 1012 // Set the terminator for the "exit" condition block. 1013 ExitConditionBlock->setTerminator(F); 1014 1015 // Now add the actual condition to the condition block. Because the condition 1016 // itself may contain control-flow, new blocks may be created. 1017 if (Stmt* C = F->getCond()) { 1018 Block = ExitConditionBlock; 1019 EntryConditionBlock = addStmt(C); 1020 assert(Block == EntryConditionBlock); 1021 1022 // If this block contains a condition variable, add both the condition 1023 // variable and initializer to the CFG. 1024 if (VarDecl *VD = F->getConditionVariable()) { 1025 if (Expr *Init = VD->getInit()) { 1026 autoCreateBlock(); 1027 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 1028 EntryConditionBlock = addStmt(Init); 1029 assert(Block == EntryConditionBlock); 1030 } 1031 } 1032 1033 if (Block) { 1034 if (!FinishBlock(EntryConditionBlock)) 1035 return 0; 1036 } 1037 } 1038 1039 // The condition block is the implicit successor for the loop body as well as 1040 // any code above the loop. 1041 Succ = EntryConditionBlock; 1042 1043 // See if this is a known constant. 1044 TryResult KnownVal(true); 1045 1046 if (F->getCond()) 1047 KnownVal = TryEvaluateBool(F->getCond()); 1048 1049 // Now create the loop body. 1050 { 1051 assert(F->getBody()); 1052 1053 // Save the current values for Block, Succ, and continue targets. 1054 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1055 save_continue(ContinueTargetBlock); 1056 1057 // Create a new block to contain the (bottom) of the loop body. 1058 Block = NULL; 1059 1060 if (Stmt* I = F->getInc()) { 1061 // Generate increment code in its own basic block. This is the target of 1062 // continue statements. 1063 Succ = addStmt(I); 1064 } else { 1065 // No increment code. Create a special, empty, block that is used as the 1066 // target block for "looping back" to the start of the loop. 1067 assert(Succ == EntryConditionBlock); 1068 Succ = createBlock(); 1069 } 1070 1071 // Finish up the increment (or empty) block if it hasn't been already. 1072 if (Block) { 1073 assert(Block == Succ); 1074 if (!FinishBlock(Block)) 1075 return 0; 1076 Block = 0; 1077 } 1078 1079 ContinueTargetBlock = Succ; 1080 1081 // The starting block for the loop increment is the block that should 1082 // represent the 'loop target' for looping back to the start of the loop. 1083 ContinueTargetBlock->setLoopTarget(F); 1084 1085 // Now populate the body block, and in the process create new blocks as we 1086 // walk the body of the loop. 1087 CFGBlock* BodyBlock = addStmt(F->getBody()); 1088 1089 if (!BodyBlock) 1090 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1091 else if (Block && !FinishBlock(BodyBlock)) 1092 return 0; 1093 1094 // This new body block is a successor to our "exit" condition block. 1095 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1096 } 1097 1098 // Link up the condition block with the code that follows the loop. (the 1099 // false branch). 1100 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1101 1102 // If the loop contains initialization, create a new block for those 1103 // statements. This block can also contain statements that precede the loop. 1104 if (Stmt* I = F->getInit()) { 1105 Block = createBlock(); 1106 return addStmt(I); 1107 } else { 1108 // There is no loop initialization. We are thus basically a while loop. 1109 // NULL out Block to force lazy block construction. 1110 Block = NULL; 1111 Succ = EntryConditionBlock; 1112 return EntryConditionBlock; 1113 } 1114} 1115 1116CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) { 1117 if (asc.alwaysAdd()) { 1118 autoCreateBlock(); 1119 AppendStmt(Block, M, asc); 1120 } 1121 return Visit(M->getBase(), 1122 M->isArrow() ? AddStmtChoice::NotAlwaysAdd 1123 : AddStmtChoice::AsLValueNotAlwaysAdd); 1124} 1125 1126CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1127 // Objective-C fast enumeration 'for' statements: 1128 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1129 // 1130 // for ( Type newVariable in collection_expression ) { statements } 1131 // 1132 // becomes: 1133 // 1134 // prologue: 1135 // 1. collection_expression 1136 // T. jump to loop_entry 1137 // loop_entry: 1138 // 1. side-effects of element expression 1139 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1140 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1141 // TB: 1142 // statements 1143 // T. jump to loop_entry 1144 // FB: 1145 // what comes after 1146 // 1147 // and 1148 // 1149 // Type existingItem; 1150 // for ( existingItem in expression ) { statements } 1151 // 1152 // becomes: 1153 // 1154 // the same with newVariable replaced with existingItem; the binding works 1155 // the same except that for one ObjCForCollectionStmt::getElement() returns 1156 // a DeclStmt and the other returns a DeclRefExpr. 1157 // 1158 1159 CFGBlock* LoopSuccessor = 0; 1160 1161 if (Block) { 1162 if (!FinishBlock(Block)) 1163 return 0; 1164 LoopSuccessor = Block; 1165 Block = 0; 1166 } else 1167 LoopSuccessor = Succ; 1168 1169 // Build the condition blocks. 1170 CFGBlock* ExitConditionBlock = createBlock(false); 1171 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1172 1173 // Set the terminator for the "exit" condition block. 1174 ExitConditionBlock->setTerminator(S); 1175 1176 // The last statement in the block should be the ObjCForCollectionStmt, which 1177 // performs the actual binding to 'element' and determines if there are any 1178 // more items in the collection. 1179 AppendStmt(ExitConditionBlock, S); 1180 Block = ExitConditionBlock; 1181 1182 // Walk the 'element' expression to see if there are any side-effects. We 1183 // generate new blocks as necesary. We DON'T add the statement by default to 1184 // the CFG unless it contains control-flow. 1185 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1186 if (Block) { 1187 if (!FinishBlock(EntryConditionBlock)) 1188 return 0; 1189 Block = 0; 1190 } 1191 1192 // The condition block is the implicit successor for the loop body as well as 1193 // any code above the loop. 1194 Succ = EntryConditionBlock; 1195 1196 // Now create the true branch. 1197 { 1198 // Save the current values for Succ, continue and break targets. 1199 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1200 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1201 1202 BreakTargetBlock = LoopSuccessor; 1203 ContinueTargetBlock = EntryConditionBlock; 1204 1205 CFGBlock* BodyBlock = addStmt(S->getBody()); 1206 1207 if (!BodyBlock) 1208 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1209 else if (Block) { 1210 if (!FinishBlock(BodyBlock)) 1211 return 0; 1212 } 1213 1214 // This new body block is a successor to our "exit" condition block. 1215 AddSuccessor(ExitConditionBlock, BodyBlock); 1216 } 1217 1218 // Link up the condition block with the code that follows the loop. 1219 // (the false branch). 1220 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1221 1222 // Now create a prologue block to contain the collection expression. 1223 Block = createBlock(); 1224 return addStmt(S->getCollection()); 1225} 1226 1227CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1228 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1229 1230 // Inline the body. 1231 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1232 1233 // The sync body starts its own basic block. This makes it a little easier 1234 // for diagnostic clients. 1235 if (SyncBlock) { 1236 if (!FinishBlock(SyncBlock)) 1237 return 0; 1238 1239 Block = 0; 1240 Succ = SyncBlock; 1241 } 1242 1243 // Inline the sync expression. 1244 return addStmt(S->getSynchExpr()); 1245} 1246 1247CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1248 // FIXME 1249 return NYS(); 1250} 1251 1252CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1253 CFGBlock* LoopSuccessor = NULL; 1254 1255 // "while" is a control-flow statement. Thus we stop processing the current 1256 // block. 1257 if (Block) { 1258 if (!FinishBlock(Block)) 1259 return 0; 1260 LoopSuccessor = Block; 1261 } else 1262 LoopSuccessor = Succ; 1263 1264 // Because of short-circuit evaluation, the condition of the loop can span 1265 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1266 // evaluate the condition. 1267 CFGBlock* ExitConditionBlock = createBlock(false); 1268 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1269 1270 // Set the terminator for the "exit" condition block. 1271 ExitConditionBlock->setTerminator(W); 1272 1273 // Now add the actual condition to the condition block. Because the condition 1274 // itself may contain control-flow, new blocks may be created. Thus we update 1275 // "Succ" after adding the condition. 1276 if (Stmt* C = W->getCond()) { 1277 Block = ExitConditionBlock; 1278 EntryConditionBlock = addStmt(C); 1279 assert(Block == EntryConditionBlock); 1280 1281 // If this block contains a condition variable, add both the condition 1282 // variable and initializer to the CFG. 1283 if (VarDecl *VD = W->getConditionVariable()) { 1284 if (Expr *Init = VD->getInit()) { 1285 autoCreateBlock(); 1286 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1287 EntryConditionBlock = addStmt(Init); 1288 assert(Block == EntryConditionBlock); 1289 } 1290 } 1291 1292 if (Block) { 1293 if (!FinishBlock(EntryConditionBlock)) 1294 return 0; 1295 } 1296 } 1297 1298 // The condition block is the implicit successor for the loop body as well as 1299 // any code above the loop. 1300 Succ = EntryConditionBlock; 1301 1302 // See if this is a known constant. 1303 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1304 1305 // Process the loop body. 1306 { 1307 assert(W->getBody()); 1308 1309 // Save the current values for Block, Succ, and continue and break targets 1310 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1311 save_continue(ContinueTargetBlock), 1312 save_break(BreakTargetBlock); 1313 1314 // Create an empty block to represent the transition block for looping back 1315 // to the head of the loop. 1316 Block = 0; 1317 assert(Succ == EntryConditionBlock); 1318 Succ = createBlock(); 1319 Succ->setLoopTarget(W); 1320 ContinueTargetBlock = Succ; 1321 1322 // All breaks should go to the code following the loop. 1323 BreakTargetBlock = LoopSuccessor; 1324 1325 // NULL out Block to force lazy instantiation of blocks for the body. 1326 Block = NULL; 1327 1328 // Create the body. The returned block is the entry to the loop body. 1329 CFGBlock* BodyBlock = addStmt(W->getBody()); 1330 1331 if (!BodyBlock) 1332 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1333 else if (Block) { 1334 if (!FinishBlock(BodyBlock)) 1335 return 0; 1336 } 1337 1338 // Add the loop body entry as a successor to the condition. 1339 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1340 } 1341 1342 // Link up the condition block with the code that follows the loop. (the 1343 // false branch). 1344 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1345 1346 // There can be no more statements in the condition block since we loop back 1347 // to this block. NULL out Block to force lazy creation of another block. 1348 Block = NULL; 1349 1350 // Return the condition block, which is the dominating block for the loop. 1351 Succ = EntryConditionBlock; 1352 return EntryConditionBlock; 1353} 1354 1355 1356CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1357 // FIXME: For now we pretend that @catch and the code it contains does not 1358 // exit. 1359 return Block; 1360} 1361 1362CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1363 // FIXME: This isn't complete. We basically treat @throw like a return 1364 // statement. 1365 1366 // If we were in the middle of a block we stop processing that block. 1367 if (Block && !FinishBlock(Block)) 1368 return 0; 1369 1370 // Create the new block. 1371 Block = createBlock(false); 1372 1373 // The Exit block is the only successor. 1374 AddSuccessor(Block, &cfg->getExit()); 1375 1376 // Add the statement to the block. This may create new blocks if S contains 1377 // control-flow (short-circuit operations). 1378 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1379} 1380 1381CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1382 // If we were in the middle of a block we stop processing that block. 1383 if (Block && !FinishBlock(Block)) 1384 return 0; 1385 1386 // Create the new block. 1387 Block = createBlock(false); 1388 1389 if (TryTerminatedBlock) 1390 // The current try statement is the only successor. 1391 AddSuccessor(Block, TryTerminatedBlock); 1392 else 1393 // otherwise the Exit block is the only successor. 1394 AddSuccessor(Block, &cfg->getExit()); 1395 1396 // Add the statement to the block. This may create new blocks if S contains 1397 // control-flow (short-circuit operations). 1398 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1399} 1400 1401CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1402 CFGBlock* LoopSuccessor = NULL; 1403 1404 // "do...while" is a control-flow statement. Thus we stop processing the 1405 // current block. 1406 if (Block) { 1407 if (!FinishBlock(Block)) 1408 return 0; 1409 LoopSuccessor = Block; 1410 } else 1411 LoopSuccessor = Succ; 1412 1413 // Because of short-circuit evaluation, the condition of the loop can span 1414 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1415 // evaluate the condition. 1416 CFGBlock* ExitConditionBlock = createBlock(false); 1417 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1418 1419 // Set the terminator for the "exit" condition block. 1420 ExitConditionBlock->setTerminator(D); 1421 1422 // Now add the actual condition to the condition block. Because the condition 1423 // itself may contain control-flow, new blocks may be created. 1424 if (Stmt* C = D->getCond()) { 1425 Block = ExitConditionBlock; 1426 EntryConditionBlock = addStmt(C); 1427 if (Block) { 1428 if (!FinishBlock(EntryConditionBlock)) 1429 return 0; 1430 } 1431 } 1432 1433 // The condition block is the implicit successor for the loop body. 1434 Succ = EntryConditionBlock; 1435 1436 // See if this is a known constant. 1437 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1438 1439 // Process the loop body. 1440 CFGBlock* BodyBlock = NULL; 1441 { 1442 assert(D->getBody()); 1443 1444 // Save the current values for Block, Succ, and continue and break targets 1445 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1446 save_continue(ContinueTargetBlock), 1447 save_break(BreakTargetBlock); 1448 1449 // All continues within this loop should go to the condition block 1450 ContinueTargetBlock = EntryConditionBlock; 1451 1452 // All breaks should go to the code following the loop. 1453 BreakTargetBlock = LoopSuccessor; 1454 1455 // NULL out Block to force lazy instantiation of blocks for the body. 1456 Block = NULL; 1457 1458 // Create the body. The returned block is the entry to the loop body. 1459 BodyBlock = addStmt(D->getBody()); 1460 1461 if (!BodyBlock) 1462 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1463 else if (Block) { 1464 if (!FinishBlock(BodyBlock)) 1465 return 0; 1466 } 1467 1468 // Add an intermediate block between the BodyBlock and the 1469 // ExitConditionBlock to represent the "loop back" transition. Create an 1470 // empty block to represent the transition block for looping back to the 1471 // head of the loop. 1472 // FIXME: Can we do this more efficiently without adding another block? 1473 Block = NULL; 1474 Succ = BodyBlock; 1475 CFGBlock *LoopBackBlock = createBlock(); 1476 LoopBackBlock->setLoopTarget(D); 1477 1478 // Add the loop body entry as a successor to the condition. 1479 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : LoopBackBlock); 1480 } 1481 1482 // Link up the condition block with the code that follows the loop. 1483 // (the false branch). 1484 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1485 1486 // There can be no more statements in the body block(s) since we loop back to 1487 // the body. NULL out Block to force lazy creation of another block. 1488 Block = NULL; 1489 1490 // Return the loop body, which is the dominating block for the loop. 1491 Succ = BodyBlock; 1492 return BodyBlock; 1493} 1494 1495CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1496 // "continue" is a control-flow statement. Thus we stop processing the 1497 // current block. 1498 if (Block && !FinishBlock(Block)) 1499 return 0; 1500 1501 // Now create a new block that ends with the continue statement. 1502 Block = createBlock(false); 1503 Block->setTerminator(C); 1504 1505 // If there is no target for the continue, then we are looking at an 1506 // incomplete AST. This means the CFG cannot be constructed. 1507 if (ContinueTargetBlock) 1508 AddSuccessor(Block, ContinueTargetBlock); 1509 else 1510 badCFG = true; 1511 1512 return Block; 1513} 1514 1515CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1516 AddStmtChoice asc) { 1517 1518 if (asc.alwaysAdd()) { 1519 autoCreateBlock(); 1520 AppendStmt(Block, E); 1521 } 1522 1523 // VLA types have expressions that must be evaluated. 1524 if (E->isArgumentType()) { 1525 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1526 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1527 addStmt(VA->getSizeExpr()); 1528 } 1529 1530 return Block; 1531} 1532 1533/// VisitStmtExpr - Utility method to handle (nested) statement 1534/// expressions (a GCC extension). 1535CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1536 if (asc.alwaysAdd()) { 1537 autoCreateBlock(); 1538 AppendStmt(Block, SE); 1539 } 1540 return VisitCompoundStmt(SE->getSubStmt()); 1541} 1542 1543CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1544 // "switch" is a control-flow statement. Thus we stop processing the current 1545 // block. 1546 CFGBlock* SwitchSuccessor = NULL; 1547 1548 if (Block) { 1549 if (!FinishBlock(Block)) 1550 return 0; 1551 SwitchSuccessor = Block; 1552 } else SwitchSuccessor = Succ; 1553 1554 // Save the current "switch" context. 1555 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1556 save_break(BreakTargetBlock), 1557 save_default(DefaultCaseBlock); 1558 1559 // Set the "default" case to be the block after the switch statement. If the 1560 // switch statement contains a "default:", this value will be overwritten with 1561 // the block for that code. 1562 DefaultCaseBlock = SwitchSuccessor; 1563 1564 // Create a new block that will contain the switch statement. 1565 SwitchTerminatedBlock = createBlock(false); 1566 1567 // Now process the switch body. The code after the switch is the implicit 1568 // successor. 1569 Succ = SwitchSuccessor; 1570 BreakTargetBlock = SwitchSuccessor; 1571 1572 // When visiting the body, the case statements should automatically get linked 1573 // up to the switch. We also don't keep a pointer to the body, since all 1574 // control-flow from the switch goes to case/default statements. 1575 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1576 Block = NULL; 1577 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1578 if (Block) { 1579 if (!FinishBlock(BodyBlock)) 1580 return 0; 1581 } 1582 1583 // If we have no "default:" case, the default transition is to the code 1584 // following the switch body. 1585 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1586 1587 // Add the terminator and condition in the switch block. 1588 SwitchTerminatedBlock->setTerminator(Terminator); 1589 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1590 Block = SwitchTerminatedBlock; 1591 Block = addStmt(Terminator->getCond()); 1592 1593 // Finally, if the SwitchStmt contains a condition variable, add both the 1594 // SwitchStmt and the condition variable initialization to the CFG. 1595 if (VarDecl *VD = Terminator->getConditionVariable()) { 1596 if (Expr *Init = VD->getInit()) { 1597 autoCreateBlock(); 1598 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1599 addStmt(Init); 1600 } 1601 } 1602 1603 return Block; 1604} 1605 1606CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1607 // CaseStmts are essentially labels, so they are the first statement in a 1608 // block. 1609 1610 if (CS->getSubStmt()) 1611 addStmt(CS->getSubStmt()); 1612 1613 CFGBlock* CaseBlock = Block; 1614 if (!CaseBlock) 1615 CaseBlock = createBlock(); 1616 1617 // Cases statements partition blocks, so this is the top of the basic block we 1618 // were processing (the "case XXX:" is the label). 1619 CaseBlock->setLabel(CS); 1620 1621 if (!FinishBlock(CaseBlock)) 1622 return 0; 1623 1624 // Add this block to the list of successors for the block with the switch 1625 // statement. 1626 assert(SwitchTerminatedBlock); 1627 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1628 1629 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1630 Block = NULL; 1631 1632 // This block is now the implicit successor of other blocks. 1633 Succ = CaseBlock; 1634 1635 return CaseBlock; 1636} 1637 1638CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1639 if (Terminator->getSubStmt()) 1640 addStmt(Terminator->getSubStmt()); 1641 1642 DefaultCaseBlock = Block; 1643 1644 if (!DefaultCaseBlock) 1645 DefaultCaseBlock = createBlock(); 1646 1647 // Default statements partition blocks, so this is the top of the basic block 1648 // we were processing (the "default:" is the label). 1649 DefaultCaseBlock->setLabel(Terminator); 1650 1651 if (!FinishBlock(DefaultCaseBlock)) 1652 return 0; 1653 1654 // Unlike case statements, we don't add the default block to the successors 1655 // for the switch statement immediately. This is done when we finish 1656 // processing the switch statement. This allows for the default case 1657 // (including a fall-through to the code after the switch statement) to always 1658 // be the last successor of a switch-terminated block. 1659 1660 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1661 Block = NULL; 1662 1663 // This block is now the implicit successor of other blocks. 1664 Succ = DefaultCaseBlock; 1665 1666 return DefaultCaseBlock; 1667} 1668 1669CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1670 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1671 // current block. 1672 CFGBlock* TrySuccessor = NULL; 1673 1674 if (Block) { 1675 if (!FinishBlock(Block)) 1676 return 0; 1677 TrySuccessor = Block; 1678 } else TrySuccessor = Succ; 1679 1680 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1681 1682 // Create a new block that will contain the try statement. 1683 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1684 // Add the terminator in the try block. 1685 NewTryTerminatedBlock->setTerminator(Terminator); 1686 1687 bool HasCatchAll = false; 1688 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1689 // The code after the try is the implicit successor. 1690 Succ = TrySuccessor; 1691 CXXCatchStmt *CS = Terminator->getHandler(h); 1692 if (CS->getExceptionDecl() == 0) { 1693 HasCatchAll = true; 1694 } 1695 Block = NULL; 1696 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1697 if (CatchBlock == 0) 1698 return 0; 1699 // Add this block to the list of successors for the block with the try 1700 // statement. 1701 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1702 } 1703 if (!HasCatchAll) { 1704 if (PrevTryTerminatedBlock) 1705 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1706 else 1707 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1708 } 1709 1710 // The code after the try is the implicit successor. 1711 Succ = TrySuccessor; 1712 1713 // Save the current "try" context. 1714 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1715 TryTerminatedBlock = NewTryTerminatedBlock; 1716 1717 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1718 Block = NULL; 1719 Block = addStmt(Terminator->getTryBlock()); 1720 return Block; 1721} 1722 1723CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1724 // CXXCatchStmt are treated like labels, so they are the first statement in a 1725 // block. 1726 1727 if (CS->getHandlerBlock()) 1728 addStmt(CS->getHandlerBlock()); 1729 1730 CFGBlock* CatchBlock = Block; 1731 if (!CatchBlock) 1732 CatchBlock = createBlock(); 1733 1734 CatchBlock->setLabel(CS); 1735 1736 if (!FinishBlock(CatchBlock)) 1737 return 0; 1738 1739 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1740 Block = NULL; 1741 1742 return CatchBlock; 1743} 1744 1745CFGBlock *CFGBuilder::VisitCXXMemberCallExpr(CXXMemberCallExpr *C, 1746 AddStmtChoice asc) { 1747 AddStmtChoice::Kind K = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 1748 : AddStmtChoice::AlwaysAdd; 1749 autoCreateBlock(); 1750 AppendStmt(Block, C, AddStmtChoice(K)); 1751 return VisitChildren(C); 1752} 1753 1754CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1755 // Lazily create the indirect-goto dispatch block if there isn't one already. 1756 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1757 1758 if (!IBlock) { 1759 IBlock = createBlock(false); 1760 cfg->setIndirectGotoBlock(IBlock); 1761 } 1762 1763 // IndirectGoto is a control-flow statement. Thus we stop processing the 1764 // current block and create a new one. 1765 if (Block && !FinishBlock(Block)) 1766 return 0; 1767 1768 Block = createBlock(false); 1769 Block->setTerminator(I); 1770 AddSuccessor(Block, IBlock); 1771 return addStmt(I->getTarget()); 1772} 1773 1774} // end anonymous namespace 1775 1776/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1777/// no successors or predecessors. If this is the first block created in the 1778/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1779CFGBlock* CFG::createBlock() { 1780 bool first_block = begin() == end(); 1781 1782 // Create the block. 1783 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1784 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1785 Blocks.push_back(Mem, BlkBVC); 1786 1787 // If this is the first block, set it as the Entry and Exit. 1788 if (first_block) 1789 Entry = Exit = &back(); 1790 1791 // Return the block. 1792 return &back(); 1793} 1794 1795/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1796/// CFG is returned to the caller. 1797CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1798 bool AddEHEdges, bool AddScopes) { 1799 CFGBuilder Builder; 1800 return Builder.buildCFG(D, Statement, C, AddEHEdges, AddScopes); 1801} 1802 1803//===----------------------------------------------------------------------===// 1804// CFG: Queries for BlkExprs. 1805//===----------------------------------------------------------------------===// 1806 1807namespace { 1808 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1809} 1810 1811static void FindSubExprAssignments(Stmt *S, 1812 llvm::SmallPtrSet<Expr*,50>& Set) { 1813 if (!S) 1814 return; 1815 1816 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1817 Stmt *child = *I; 1818 if (!child) 1819 continue; 1820 1821 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1822 if (B->isAssignmentOp()) Set.insert(B); 1823 1824 FindSubExprAssignments(child, Set); 1825 } 1826} 1827 1828static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1829 BlkExprMapTy* M = new BlkExprMapTy(); 1830 1831 // Look for assignments that are used as subexpressions. These are the only 1832 // assignments that we want to *possibly* register as a block-level 1833 // expression. Basically, if an assignment occurs both in a subexpression and 1834 // at the block-level, it is a block-level expression. 1835 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1836 1837 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1838 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1839 FindSubExprAssignments(*BI, SubExprAssignments); 1840 1841 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1842 1843 // Iterate over the statements again on identify the Expr* and Stmt* at the 1844 // block-level that are block-level expressions. 1845 1846 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1847 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1848 1849 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1850 // Assignment expressions that are not nested within another 1851 // expression are really "statements" whose value is never used by 1852 // another expression. 1853 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1854 continue; 1855 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1856 // Special handling for statement expressions. The last statement in 1857 // the statement expression is also a block-level expr. 1858 const CompoundStmt* C = Terminator->getSubStmt(); 1859 if (!C->body_empty()) { 1860 unsigned x = M->size(); 1861 (*M)[C->body_back()] = x; 1862 } 1863 } 1864 1865 unsigned x = M->size(); 1866 (*M)[Exp] = x; 1867 } 1868 1869 // Look at terminators. The condition is a block-level expression. 1870 1871 Stmt* S = (*I)->getTerminatorCondition(); 1872 1873 if (S && M->find(S) == M->end()) { 1874 unsigned x = M->size(); 1875 (*M)[S] = x; 1876 } 1877 } 1878 1879 return M; 1880} 1881 1882CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1883 assert(S != NULL); 1884 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1885 1886 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1887 BlkExprMapTy::iterator I = M->find(S); 1888 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1889} 1890 1891unsigned CFG::getNumBlkExprs() { 1892 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1893 return M->size(); 1894 else { 1895 // We assume callers interested in the number of BlkExprs will want 1896 // the map constructed if it doesn't already exist. 1897 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1898 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1899 } 1900} 1901 1902//===----------------------------------------------------------------------===// 1903// Cleanup: CFG dstor. 1904//===----------------------------------------------------------------------===// 1905 1906CFG::~CFG() { 1907 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1908} 1909 1910//===----------------------------------------------------------------------===// 1911// CFG pretty printing 1912//===----------------------------------------------------------------------===// 1913 1914namespace { 1915 1916class StmtPrinterHelper : public PrinterHelper { 1917 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1918 StmtMapTy StmtMap; 1919 signed CurrentBlock; 1920 unsigned CurrentStmt; 1921 const LangOptions &LangOpts; 1922public: 1923 1924 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1925 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1926 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1927 unsigned j = 1; 1928 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1929 BI != BEnd; ++BI, ++j ) 1930 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1931 } 1932 } 1933 1934 virtual ~StmtPrinterHelper() {} 1935 1936 const LangOptions &getLangOpts() const { return LangOpts; } 1937 void setBlockID(signed i) { CurrentBlock = i; } 1938 void setStmtID(unsigned i) { CurrentStmt = i; } 1939 1940 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1941 1942 StmtMapTy::iterator I = StmtMap.find(Terminator); 1943 1944 if (I == StmtMap.end()) 1945 return false; 1946 1947 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 1948 && I->second.second == CurrentStmt) { 1949 return false; 1950 } 1951 1952 OS << "[B" << I->second.first << "." << I->second.second << "]"; 1953 return true; 1954 } 1955}; 1956} // end anonymous namespace 1957 1958 1959namespace { 1960class CFGBlockTerminatorPrint 1961 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 1962 1963 llvm::raw_ostream& OS; 1964 StmtPrinterHelper* Helper; 1965 PrintingPolicy Policy; 1966public: 1967 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 1968 const PrintingPolicy &Policy) 1969 : OS(os), Helper(helper), Policy(Policy) {} 1970 1971 void VisitIfStmt(IfStmt* I) { 1972 OS << "if "; 1973 I->getCond()->printPretty(OS,Helper,Policy); 1974 } 1975 1976 // Default case. 1977 void VisitStmt(Stmt* Terminator) { 1978 Terminator->printPretty(OS, Helper, Policy); 1979 } 1980 1981 void VisitForStmt(ForStmt* F) { 1982 OS << "for (" ; 1983 if (F->getInit()) 1984 OS << "..."; 1985 OS << "; "; 1986 if (Stmt* C = F->getCond()) 1987 C->printPretty(OS, Helper, Policy); 1988 OS << "; "; 1989 if (F->getInc()) 1990 OS << "..."; 1991 OS << ")"; 1992 } 1993 1994 void VisitWhileStmt(WhileStmt* W) { 1995 OS << "while " ; 1996 if (Stmt* C = W->getCond()) 1997 C->printPretty(OS, Helper, Policy); 1998 } 1999 2000 void VisitDoStmt(DoStmt* D) { 2001 OS << "do ... while "; 2002 if (Stmt* C = D->getCond()) 2003 C->printPretty(OS, Helper, Policy); 2004 } 2005 2006 void VisitSwitchStmt(SwitchStmt* Terminator) { 2007 OS << "switch "; 2008 Terminator->getCond()->printPretty(OS, Helper, Policy); 2009 } 2010 2011 void VisitCXXTryStmt(CXXTryStmt* CS) { 2012 OS << "try ..."; 2013 } 2014 2015 void VisitConditionalOperator(ConditionalOperator* C) { 2016 C->getCond()->printPretty(OS, Helper, Policy); 2017 OS << " ? ... : ..."; 2018 } 2019 2020 void VisitChooseExpr(ChooseExpr* C) { 2021 OS << "__builtin_choose_expr( "; 2022 C->getCond()->printPretty(OS, Helper, Policy); 2023 OS << " )"; 2024 } 2025 2026 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 2027 OS << "goto *"; 2028 I->getTarget()->printPretty(OS, Helper, Policy); 2029 } 2030 2031 void VisitBinaryOperator(BinaryOperator* B) { 2032 if (!B->isLogicalOp()) { 2033 VisitExpr(B); 2034 return; 2035 } 2036 2037 B->getLHS()->printPretty(OS, Helper, Policy); 2038 2039 switch (B->getOpcode()) { 2040 case BinaryOperator::LOr: 2041 OS << " || ..."; 2042 return; 2043 case BinaryOperator::LAnd: 2044 OS << " && ..."; 2045 return; 2046 default: 2047 assert(false && "Invalid logical operator."); 2048 } 2049 } 2050 2051 void VisitExpr(Expr* E) { 2052 E->printPretty(OS, Helper, Policy); 2053 } 2054}; 2055} // end anonymous namespace 2056 2057 2058static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2059 const CFGElement &E) { 2060 Stmt *Terminator = E; 2061 2062 if (E.asStartScope()) { 2063 OS << "start scope\n"; 2064 return; 2065 } 2066 if (E.asEndScope()) { 2067 OS << "end scope\n"; 2068 return; 2069 } 2070 2071 if (Helper) { 2072 // special printing for statement-expressions. 2073 if (StmtExpr* SE = dyn_cast<StmtExpr>(Terminator)) { 2074 CompoundStmt* Sub = SE->getSubStmt(); 2075 2076 if (Sub->child_begin() != Sub->child_end()) { 2077 OS << "({ ... ; "; 2078 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2079 OS << " })\n"; 2080 return; 2081 } 2082 } 2083 2084 // special printing for comma expressions. 2085 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Terminator)) { 2086 if (B->getOpcode() == BinaryOperator::Comma) { 2087 OS << "... , "; 2088 Helper->handledStmt(B->getRHS(),OS); 2089 OS << '\n'; 2090 return; 2091 } 2092 } 2093 } 2094 2095 Terminator->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2096 2097 // Expressions need a newline. 2098 if (isa<Expr>(Terminator)) OS << '\n'; 2099} 2100 2101static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2102 const CFGBlock& B, 2103 StmtPrinterHelper* Helper, bool print_edges) { 2104 2105 if (Helper) Helper->setBlockID(B.getBlockID()); 2106 2107 // Print the header. 2108 OS << "\n [ B" << B.getBlockID(); 2109 2110 if (&B == &cfg->getEntry()) 2111 OS << " (ENTRY) ]\n"; 2112 else if (&B == &cfg->getExit()) 2113 OS << " (EXIT) ]\n"; 2114 else if (&B == cfg->getIndirectGotoBlock()) 2115 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2116 else 2117 OS << " ]\n"; 2118 2119 // Print the label of this block. 2120 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2121 2122 if (print_edges) 2123 OS << " "; 2124 2125 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2126 OS << L->getName(); 2127 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2128 OS << "case "; 2129 C->getLHS()->printPretty(OS, Helper, 2130 PrintingPolicy(Helper->getLangOpts())); 2131 if (C->getRHS()) { 2132 OS << " ... "; 2133 C->getRHS()->printPretty(OS, Helper, 2134 PrintingPolicy(Helper->getLangOpts())); 2135 } 2136 } else if (isa<DefaultStmt>(Label)) 2137 OS << "default"; 2138 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2139 OS << "catch ("; 2140 if (CS->getExceptionDecl()) 2141 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2142 0); 2143 else 2144 OS << "..."; 2145 OS << ")"; 2146 2147 } else 2148 assert(false && "Invalid label statement in CFGBlock."); 2149 2150 OS << ":\n"; 2151 } 2152 2153 // Iterate through the statements in the block and print them. 2154 unsigned j = 1; 2155 2156 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2157 I != E ; ++I, ++j ) { 2158 2159 // Print the statement # in the basic block and the statement itself. 2160 if (print_edges) 2161 OS << " "; 2162 2163 OS << llvm::format("%3d", j) << ": "; 2164 2165 if (Helper) 2166 Helper->setStmtID(j); 2167 2168 print_stmt(OS,Helper,*I); 2169 } 2170 2171 // Print the terminator of this block. 2172 if (B.getTerminator()) { 2173 if (print_edges) 2174 OS << " "; 2175 2176 OS << " T: "; 2177 2178 if (Helper) Helper->setBlockID(-1); 2179 2180 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2181 PrintingPolicy(Helper->getLangOpts())); 2182 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2183 OS << '\n'; 2184 } 2185 2186 if (print_edges) { 2187 // Print the predecessors of this block. 2188 OS << " Predecessors (" << B.pred_size() << "):"; 2189 unsigned i = 0; 2190 2191 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2192 I != E; ++I, ++i) { 2193 2194 if (i == 8 || (i-8) == 0) 2195 OS << "\n "; 2196 2197 OS << " B" << (*I)->getBlockID(); 2198 } 2199 2200 OS << '\n'; 2201 2202 // Print the successors of this block. 2203 OS << " Successors (" << B.succ_size() << "):"; 2204 i = 0; 2205 2206 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2207 I != E; ++I, ++i) { 2208 2209 if (i == 8 || (i-8) % 10 == 0) 2210 OS << "\n "; 2211 2212 if (*I) 2213 OS << " B" << (*I)->getBlockID(); 2214 else 2215 OS << " NULL"; 2216 } 2217 2218 OS << '\n'; 2219 } 2220} 2221 2222 2223/// dump - A simple pretty printer of a CFG that outputs to stderr. 2224void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2225 2226/// print - A simple pretty printer of a CFG that outputs to an ostream. 2227void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2228 StmtPrinterHelper Helper(this, LO); 2229 2230 // Print the entry block. 2231 print_block(OS, this, getEntry(), &Helper, true); 2232 2233 // Iterate through the CFGBlocks and print them one by one. 2234 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2235 // Skip the entry block, because we already printed it. 2236 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2237 continue; 2238 2239 print_block(OS, this, **I, &Helper, true); 2240 } 2241 2242 // Print the exit block. 2243 print_block(OS, this, getExit(), &Helper, true); 2244 OS.flush(); 2245} 2246 2247/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2248void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2249 print(llvm::errs(), cfg, LO); 2250} 2251 2252/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2253/// Generally this will only be called from CFG::print. 2254void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2255 const LangOptions &LO) const { 2256 StmtPrinterHelper Helper(cfg, LO); 2257 print_block(OS, cfg, *this, &Helper, true); 2258} 2259 2260/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2261void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2262 const LangOptions &LO) const { 2263 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2264 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2265} 2266 2267Stmt* CFGBlock::getTerminatorCondition() { 2268 2269 if (!Terminator) 2270 return NULL; 2271 2272 Expr* E = NULL; 2273 2274 switch (Terminator->getStmtClass()) { 2275 default: 2276 break; 2277 2278 case Stmt::ForStmtClass: 2279 E = cast<ForStmt>(Terminator)->getCond(); 2280 break; 2281 2282 case Stmt::WhileStmtClass: 2283 E = cast<WhileStmt>(Terminator)->getCond(); 2284 break; 2285 2286 case Stmt::DoStmtClass: 2287 E = cast<DoStmt>(Terminator)->getCond(); 2288 break; 2289 2290 case Stmt::IfStmtClass: 2291 E = cast<IfStmt>(Terminator)->getCond(); 2292 break; 2293 2294 case Stmt::ChooseExprClass: 2295 E = cast<ChooseExpr>(Terminator)->getCond(); 2296 break; 2297 2298 case Stmt::IndirectGotoStmtClass: 2299 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2300 break; 2301 2302 case Stmt::SwitchStmtClass: 2303 E = cast<SwitchStmt>(Terminator)->getCond(); 2304 break; 2305 2306 case Stmt::ConditionalOperatorClass: 2307 E = cast<ConditionalOperator>(Terminator)->getCond(); 2308 break; 2309 2310 case Stmt::BinaryOperatorClass: // '&&' and '||' 2311 E = cast<BinaryOperator>(Terminator)->getLHS(); 2312 break; 2313 2314 case Stmt::ObjCForCollectionStmtClass: 2315 return Terminator; 2316 } 2317 2318 return E ? E->IgnoreParens() : NULL; 2319} 2320 2321bool CFGBlock::hasBinaryBranchTerminator() const { 2322 2323 if (!Terminator) 2324 return false; 2325 2326 Expr* E = NULL; 2327 2328 switch (Terminator->getStmtClass()) { 2329 default: 2330 return false; 2331 2332 case Stmt::ForStmtClass: 2333 case Stmt::WhileStmtClass: 2334 case Stmt::DoStmtClass: 2335 case Stmt::IfStmtClass: 2336 case Stmt::ChooseExprClass: 2337 case Stmt::ConditionalOperatorClass: 2338 case Stmt::BinaryOperatorClass: 2339 return true; 2340 } 2341 2342 return E ? E->IgnoreParens() : NULL; 2343} 2344 2345 2346//===----------------------------------------------------------------------===// 2347// CFG Graphviz Visualization 2348//===----------------------------------------------------------------------===// 2349 2350 2351#ifndef NDEBUG 2352static StmtPrinterHelper* GraphHelper; 2353#endif 2354 2355void CFG::viewCFG(const LangOptions &LO) const { 2356#ifndef NDEBUG 2357 StmtPrinterHelper H(this, LO); 2358 GraphHelper = &H; 2359 llvm::ViewGraph(this,"CFG"); 2360 GraphHelper = NULL; 2361#endif 2362} 2363 2364namespace llvm { 2365template<> 2366struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2367 2368 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2369 2370 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2371 2372#ifndef NDEBUG 2373 std::string OutSStr; 2374 llvm::raw_string_ostream Out(OutSStr); 2375 print_block(Out,Graph, *Node, GraphHelper, false); 2376 std::string& OutStr = Out.str(); 2377 2378 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2379 2380 // Process string output to make it nicer... 2381 for (unsigned i = 0; i != OutStr.length(); ++i) 2382 if (OutStr[i] == '\n') { // Left justify 2383 OutStr[i] = '\\'; 2384 OutStr.insert(OutStr.begin()+i+1, 'l'); 2385 } 2386 2387 return OutStr; 2388#else 2389 return ""; 2390#endif 2391 } 2392}; 2393} // end namespace llvm 2394