CFG.cpp revision 12e3f890b96bbb747f196db51c7178716136ec8b
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, 103 bool pruneTriviallyFalseEdges, bool AddEHEdges, 104 bool AddScopes); 105 106private: 107 // Visitors to walk an AST and construct the CFG. 108 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc); 109 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc); 110 CFGBlock *VisitBlockExpr(BlockExpr* E, AddStmtChoice asc); 111 CFGBlock *VisitBreakStmt(BreakStmt *B); 112 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S); 113 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 114 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 115 CFGBlock *VisitCXXMemberCallExpr(CXXMemberCallExpr *C, AddStmtChoice asc); 116 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 117 CFGBlock *VisitCaseStmt(CaseStmt *C); 118 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 119 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 120 CFGBlock *VisitConditionalOperator(ConditionalOperator *C, AddStmtChoice asc); 121 CFGBlock *VisitContinueStmt(ContinueStmt *C); 122 CFGBlock *VisitDeclStmt(DeclStmt *DS); 123 CFGBlock *VisitDeclSubExpr(Decl* D); 124 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 125 CFGBlock *VisitDoStmt(DoStmt *D); 126 CFGBlock *VisitForStmt(ForStmt *F); 127 CFGBlock *VisitGotoStmt(GotoStmt* G); 128 CFGBlock *VisitIfStmt(IfStmt *I); 129 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 130 CFGBlock *VisitLabelStmt(LabelStmt *L); 131 CFGBlock *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc); 132 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 133 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 134 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 135 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 136 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 137 CFGBlock *VisitReturnStmt(ReturnStmt* R); 138 CFGBlock *VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, AddStmtChoice asc); 139 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 140 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 141 CFGBlock *VisitWhileStmt(WhileStmt *W); 142 143 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 144 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 145 CFGBlock *VisitChildren(Stmt* S); 146 147 // NYS == Not Yet Supported 148 CFGBlock* NYS() { 149 badCFG = true; 150 return Block; 151 } 152 153 CFGBlock *StartScope(Stmt *S, CFGBlock *B) { 154 if (!AddScopes) 155 return B; 156 157 if (B == 0) 158 B = createBlock(); 159 B->StartScope(S, cfg->getBumpVectorContext()); 160 return B; 161 } 162 163 void EndScope(Stmt *S) { 164 if (!AddScopes) 165 return; 166 167 if (Block == 0) 168 Block = createBlock(); 169 Block->EndScope(S, cfg->getBumpVectorContext()); 170 } 171 172 void autoCreateBlock() { if (!Block) Block = createBlock(); } 173 CFGBlock *createBlock(bool add_successor = true); 174 bool FinishBlock(CFGBlock* B); 175 CFGBlock *addStmt(Stmt *S) { 176 return Visit(S, AddStmtChoice::AlwaysAdd); 177 } 178 179 void AppendStmt(CFGBlock *B, Stmt *S, 180 AddStmtChoice asc = AddStmtChoice::AlwaysAdd) { 181 B->appendStmt(S, cfg->getBumpVectorContext(), asc.asLValue()); 182 } 183 184 void AddSuccessor(CFGBlock *B, CFGBlock *S) { 185 B->addSuccessor(S, cfg->getBumpVectorContext()); 186 } 187 188 /// TryResult - a class representing a variant over the values 189 /// 'true', 'false', or 'unknown'. This is returned by TryEvaluateBool, 190 /// and is used by the CFGBuilder to decide if a branch condition 191 /// can be decided up front during CFG construction. 192 class TryResult { 193 int X; 194 public: 195 TryResult(bool b) : X(b ? 1 : 0) {} 196 TryResult() : X(-1) {} 197 198 bool isTrue() const { return X == 1; } 199 bool isFalse() const { return X == 0; } 200 bool isKnown() const { return X >= 0; } 201 void negate() { 202 assert(isKnown()); 203 X ^= 0x1; 204 } 205 }; 206 207 /// TryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 208 /// if we can evaluate to a known value, otherwise return -1. 209 TryResult TryEvaluateBool(Expr *S) { 210 if (!PruneTriviallyFalseEdges) 211 return TryResult(); 212 213 Expr::EvalResult Result; 214 if (!S->isTypeDependent() && !S->isValueDependent() && 215 S->Evaluate(Result, *Context) && Result.Val.isInt()) 216 return Result.Val.getInt().getBoolValue(); 217 218 return TryResult(); 219 } 220 221 bool badCFG; 222 223 // True iff trivially false edges should be pruned from the CFG. 224 bool PruneTriviallyFalseEdges; 225 226 // True iff EH edges on CallExprs should be added to the CFG. 227 bool AddEHEdges; 228 229 // True iff scope start and scope end notes should be added to the CFG. 230 bool AddScopes; 231}; 232 233// FIXME: Add support for dependent-sized array types in C++? 234// Does it even make sense to build a CFG for an uninstantiated template? 235static VariableArrayType* FindVA(Type* t) { 236 while (ArrayType* vt = dyn_cast<ArrayType>(t)) { 237 if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt)) 238 if (vat->getSizeExpr()) 239 return vat; 240 241 t = vt->getElementType().getTypePtr(); 242 } 243 244 return 0; 245} 246 247/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 248/// arbitrary statement. Examples include a single expression or a function 249/// body (compound statement). The ownership of the returned CFG is 250/// transferred to the caller. If CFG construction fails, this method returns 251/// NULL. 252CFG* CFGBuilder::buildCFG(const Decl *D, Stmt* Statement, ASTContext* C, 253 bool pruneTriviallyFalseEdges, 254 bool addehedges, bool AddScopes) { 255 256 AddEHEdges = addehedges; 257 PruneTriviallyFalseEdges = pruneTriviallyFalseEdges; 258 259 Context = C; 260 assert(cfg.get()); 261 if (!Statement) 262 return NULL; 263 264 this->AddScopes = AddScopes; 265 badCFG = false; 266 267 // Create an empty block that will serve as the exit block for the CFG. Since 268 // this is the first block added to the CFG, it will be implicitly registered 269 // as the exit block. 270 Succ = createBlock(); 271 assert(Succ == &cfg->getExit()); 272 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 273 274 // Visit the statements and create the CFG. 275 CFGBlock* B = addStmt(Statement); 276 277 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 278 // FIXME: Add code for base initializers and member initializers. 279 (void)CD; 280 } 281 if (!B) 282 B = Succ; 283 284 if (B) { 285 // Finalize the last constructed block. This usually involves reversing the 286 // order of the statements in the block. 287 if (Block) FinishBlock(B); 288 289 // Backpatch the gotos whose label -> block mappings we didn't know when we 290 // encountered them. 291 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 292 E = BackpatchBlocks.end(); I != E; ++I ) { 293 294 CFGBlock* B = *I; 295 GotoStmt* G = cast<GotoStmt>(B->getTerminator()); 296 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 297 298 // If there is no target for the goto, then we are looking at an 299 // incomplete AST. Handle this by not registering a successor. 300 if (LI == LabelMap.end()) continue; 301 302 AddSuccessor(B, LI->second); 303 } 304 305 // Add successors to the Indirect Goto Dispatch block (if we have one). 306 if (CFGBlock* B = cfg->getIndirectGotoBlock()) 307 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 308 E = AddressTakenLabels.end(); I != E; ++I ) { 309 310 // Lookup the target block. 311 LabelMapTy::iterator LI = LabelMap.find(*I); 312 313 // If there is no target block that contains label, then we are looking 314 // at an incomplete AST. Handle this by not registering a successor. 315 if (LI == LabelMap.end()) continue; 316 317 AddSuccessor(B, LI->second); 318 } 319 320 Succ = B; 321 } 322 323 // Create an empty entry block that has no predecessors. 324 cfg->setEntry(createBlock()); 325 326 return badCFG ? NULL : cfg.take(); 327} 328 329/// createBlock - Used to lazily create blocks that are connected 330/// to the current (global) succcessor. 331CFGBlock* CFGBuilder::createBlock(bool add_successor) { 332 CFGBlock* B = cfg->createBlock(); 333 if (add_successor && Succ) 334 AddSuccessor(B, Succ); 335 return B; 336} 337 338/// FinishBlock - "Finalize" the block by checking if we have a bad CFG. 339bool CFGBuilder::FinishBlock(CFGBlock* B) { 340 if (badCFG) 341 return false; 342 343 assert(B); 344 return true; 345} 346 347/// Visit - Walk the subtree of a statement and add extra 348/// blocks for ternary operators, &&, and ||. We also process "," and 349/// DeclStmts (which may contain nested control-flow). 350CFGBlock* CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 351tryAgain: 352 if (!S) { 353 badCFG = true; 354 return 0; 355 } 356 switch (S->getStmtClass()) { 357 default: 358 return VisitStmt(S, asc); 359 360 case Stmt::AddrLabelExprClass: 361 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 362 363 case Stmt::BinaryOperatorClass: 364 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 365 366 case Stmt::BlockExprClass: 367 return VisitBlockExpr(cast<BlockExpr>(S), asc); 368 369 case Stmt::BreakStmtClass: 370 return VisitBreakStmt(cast<BreakStmt>(S)); 371 372 case Stmt::CallExprClass: 373 case Stmt::CXXOperatorCallExprClass: 374 return VisitCallExpr(cast<CallExpr>(S), asc); 375 376 case Stmt::CaseStmtClass: 377 return VisitCaseStmt(cast<CaseStmt>(S)); 378 379 case Stmt::ChooseExprClass: 380 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 381 382 case Stmt::CompoundStmtClass: 383 return VisitCompoundStmt(cast<CompoundStmt>(S)); 384 385 case Stmt::ConditionalOperatorClass: 386 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 387 388 case Stmt::ContinueStmtClass: 389 return VisitContinueStmt(cast<ContinueStmt>(S)); 390 391 case Stmt::CXXCatchStmtClass: 392 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 393 394 case Stmt::CXXExprWithTemporariesClass: { 395 // FIXME: Handle temporaries. For now, just visit the subexpression 396 // so we don't artificially create extra blocks. 397 return Visit(cast<CXXExprWithTemporaries>(S)->getSubExpr(), asc); 398 } 399 400 case Stmt::CXXMemberCallExprClass: 401 return VisitCXXMemberCallExpr(cast<CXXMemberCallExpr>(S), asc); 402 403 case Stmt::CXXThrowExprClass: 404 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 405 406 case Stmt::CXXTryStmtClass: 407 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 408 409 case Stmt::DeclStmtClass: 410 return VisitDeclStmt(cast<DeclStmt>(S)); 411 412 case Stmt::DefaultStmtClass: 413 return VisitDefaultStmt(cast<DefaultStmt>(S)); 414 415 case Stmt::DoStmtClass: 416 return VisitDoStmt(cast<DoStmt>(S)); 417 418 case Stmt::ForStmtClass: 419 return VisitForStmt(cast<ForStmt>(S)); 420 421 case Stmt::GotoStmtClass: 422 return VisitGotoStmt(cast<GotoStmt>(S)); 423 424 case Stmt::IfStmtClass: 425 return VisitIfStmt(cast<IfStmt>(S)); 426 427 case Stmt::IndirectGotoStmtClass: 428 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 429 430 case Stmt::LabelStmtClass: 431 return VisitLabelStmt(cast<LabelStmt>(S)); 432 433 case Stmt::MemberExprClass: 434 return VisitMemberExpr(cast<MemberExpr>(S), asc); 435 436 case Stmt::ObjCAtCatchStmtClass: 437 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 438 439 case Stmt::ObjCAtSynchronizedStmtClass: 440 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 441 442 case Stmt::ObjCAtThrowStmtClass: 443 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 444 445 case Stmt::ObjCAtTryStmtClass: 446 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 447 448 case Stmt::ObjCForCollectionStmtClass: 449 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 450 451 case Stmt::ParenExprClass: 452 S = cast<ParenExpr>(S)->getSubExpr(); 453 goto tryAgain; 454 455 case Stmt::NullStmtClass: 456 return Block; 457 458 case Stmt::ReturnStmtClass: 459 return VisitReturnStmt(cast<ReturnStmt>(S)); 460 461 case Stmt::SizeOfAlignOfExprClass: 462 return VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), asc); 463 464 case Stmt::StmtExprClass: 465 return VisitStmtExpr(cast<StmtExpr>(S), asc); 466 467 case Stmt::SwitchStmtClass: 468 return VisitSwitchStmt(cast<SwitchStmt>(S)); 469 470 case Stmt::WhileStmtClass: 471 return VisitWhileStmt(cast<WhileStmt>(S)); 472 } 473} 474 475CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 476 if (asc.alwaysAdd()) { 477 autoCreateBlock(); 478 AppendStmt(Block, S, asc); 479 } 480 481 return VisitChildren(S); 482} 483 484/// VisitChildren - Visit the children of a Stmt. 485CFGBlock *CFGBuilder::VisitChildren(Stmt* Terminator) { 486 CFGBlock *B = Block; 487 for (Stmt::child_iterator I = Terminator->child_begin(), 488 E = Terminator->child_end(); I != E; ++I) { 489 if (*I) B = Visit(*I); 490 } 491 return B; 492} 493 494CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 495 AddStmtChoice asc) { 496 AddressTakenLabels.insert(A->getLabel()); 497 498 if (asc.alwaysAdd()) { 499 autoCreateBlock(); 500 AppendStmt(Block, A, asc); 501 } 502 503 return Block; 504} 505 506CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 507 AddStmtChoice asc) { 508 if (B->isLogicalOp()) { // && or || 509 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 510 AppendStmt(ConfluenceBlock, B, asc); 511 512 if (!FinishBlock(ConfluenceBlock)) 513 return 0; 514 515 // create the block evaluating the LHS 516 CFGBlock* LHSBlock = createBlock(false); 517 LHSBlock->setTerminator(B); 518 519 // create the block evaluating the RHS 520 Succ = ConfluenceBlock; 521 Block = NULL; 522 CFGBlock* RHSBlock = addStmt(B->getRHS()); 523 524 if (RHSBlock) { 525 if (!FinishBlock(RHSBlock)) 526 return 0; 527 } 528 else { 529 // Create an empty block for cases where the RHS doesn't require 530 // any explicit statements in the CFG. 531 RHSBlock = createBlock(); 532 } 533 534 // See if this is a known constant. 535 TryResult KnownVal = TryEvaluateBool(B->getLHS()); 536 if (KnownVal.isKnown() && (B->getOpcode() == BO_LOr)) 537 KnownVal.negate(); 538 539 // Now link the LHSBlock with RHSBlock. 540 if (B->getOpcode() == BO_LOr) { 541 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 542 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 543 } else { 544 assert(B->getOpcode() == BO_LAnd); 545 AddSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 546 AddSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 547 } 548 549 // Generate the blocks for evaluating the LHS. 550 Block = LHSBlock; 551 return addStmt(B->getLHS()); 552 } 553 else if (B->getOpcode() == BO_Comma) { // , 554 autoCreateBlock(); 555 AppendStmt(Block, B, asc); 556 addStmt(B->getRHS()); 557 return addStmt(B->getLHS()); 558 } 559 else if (B->isAssignmentOp()) { 560 if (asc.alwaysAdd()) { 561 autoCreateBlock(); 562 AppendStmt(Block, B, asc); 563 } 564 565 Visit(B->getRHS()); 566 return Visit(B->getLHS(), AddStmtChoice::AsLValueNotAlwaysAdd); 567 } 568 569 return VisitStmt(B, asc); 570} 571 572CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 573 if (asc.alwaysAdd()) { 574 autoCreateBlock(); 575 AppendStmt(Block, E, asc); 576 } 577 return Block; 578} 579 580CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 581 // "break" is a control-flow statement. Thus we stop processing the current 582 // block. 583 if (Block && !FinishBlock(Block)) 584 return 0; 585 586 // Now create a new block that ends with the break statement. 587 Block = createBlock(false); 588 Block->setTerminator(B); 589 590 // If there is no target for the break, then we are looking at an incomplete 591 // AST. This means that the CFG cannot be constructed. 592 if (BreakTargetBlock) 593 AddSuccessor(Block, BreakTargetBlock); 594 else 595 badCFG = true; 596 597 598 return Block; 599} 600 601static bool CanThrow(Expr *E) { 602 QualType Ty = E->getType(); 603 if (Ty->isFunctionPointerType()) 604 Ty = Ty->getAs<PointerType>()->getPointeeType(); 605 else if (Ty->isBlockPointerType()) 606 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 607 608 const FunctionType *FT = Ty->getAs<FunctionType>(); 609 if (FT) { 610 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 611 if (Proto->hasEmptyExceptionSpec()) 612 return false; 613 } 614 return true; 615} 616 617CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 618 // If this is a call to a no-return function, this stops the block here. 619 bool NoReturn = false; 620 if (getFunctionExtInfo(*C->getCallee()->getType()).getNoReturn()) { 621 NoReturn = true; 622 } 623 624 bool AddEHEdge = false; 625 626 // Languages without exceptions are assumed to not throw. 627 if (Context->getLangOptions().Exceptions) { 628 if (AddEHEdges) 629 AddEHEdge = true; 630 } 631 632 if (FunctionDecl *FD = C->getDirectCallee()) { 633 if (FD->hasAttr<NoReturnAttr>()) 634 NoReturn = true; 635 if (FD->hasAttr<NoThrowAttr>()) 636 AddEHEdge = false; 637 } 638 639 if (!CanThrow(C->getCallee())) 640 AddEHEdge = false; 641 642 if (!NoReturn && !AddEHEdge) { 643 if (asc.asLValue()) 644 return VisitStmt(C, AddStmtChoice::AlwaysAddAsLValue); 645 else 646 return VisitStmt(C, AddStmtChoice::AlwaysAdd); 647 } 648 649 if (Block) { 650 Succ = Block; 651 if (!FinishBlock(Block)) 652 return 0; 653 } 654 655 Block = createBlock(!NoReturn); 656 AppendStmt(Block, C, asc); 657 658 if (NoReturn) { 659 // Wire this to the exit block directly. 660 AddSuccessor(Block, &cfg->getExit()); 661 } 662 if (AddEHEdge) { 663 // Add exceptional edges. 664 if (TryTerminatedBlock) 665 AddSuccessor(Block, TryTerminatedBlock); 666 else 667 AddSuccessor(Block, &cfg->getExit()); 668 } 669 670 return VisitChildren(C); 671} 672 673CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 674 AddStmtChoice asc) { 675 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 676 AppendStmt(ConfluenceBlock, C, asc); 677 if (!FinishBlock(ConfluenceBlock)) 678 return 0; 679 680 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 681 : AddStmtChoice::AlwaysAdd; 682 683 Succ = ConfluenceBlock; 684 Block = NULL; 685 CFGBlock* LHSBlock = Visit(C->getLHS(), asc); 686 if (!FinishBlock(LHSBlock)) 687 return 0; 688 689 Succ = ConfluenceBlock; 690 Block = NULL; 691 CFGBlock* RHSBlock = Visit(C->getRHS(), asc); 692 if (!FinishBlock(RHSBlock)) 693 return 0; 694 695 Block = createBlock(false); 696 // See if this is a known constant. 697 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 698 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 699 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 700 Block->setTerminator(C); 701 return addStmt(C->getCond()); 702} 703 704 705CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) { 706 EndScope(C); 707 708 CFGBlock* LastBlock = Block; 709 710 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 711 I != E; ++I ) { 712 // If we hit a segment of code just containing ';' (NullStmts), we can 713 // get a null block back. In such cases, just use the LastBlock 714 if (CFGBlock *newBlock = addStmt(*I)) 715 LastBlock = newBlock; 716 717 if (badCFG) 718 return NULL; 719 } 720 721 LastBlock = StartScope(C, LastBlock); 722 723 return LastBlock; 724} 725 726CFGBlock *CFGBuilder::VisitConditionalOperator(ConditionalOperator *C, 727 AddStmtChoice asc) { 728 // Create the confluence block that will "merge" the results of the ternary 729 // expression. 730 CFGBlock* ConfluenceBlock = Block ? Block : createBlock(); 731 AppendStmt(ConfluenceBlock, C, asc); 732 if (!FinishBlock(ConfluenceBlock)) 733 return 0; 734 735 asc = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 736 : AddStmtChoice::AlwaysAdd; 737 738 // Create a block for the LHS expression if there is an LHS expression. A 739 // GCC extension allows LHS to be NULL, causing the condition to be the 740 // value that is returned instead. 741 // e.g: x ?: y is shorthand for: x ? x : y; 742 Succ = ConfluenceBlock; 743 Block = NULL; 744 CFGBlock* LHSBlock = NULL; 745 if (C->getLHS()) { 746 LHSBlock = Visit(C->getLHS(), asc); 747 if (!FinishBlock(LHSBlock)) 748 return 0; 749 Block = NULL; 750 } 751 752 // Create the block for the RHS expression. 753 Succ = ConfluenceBlock; 754 CFGBlock* RHSBlock = Visit(C->getRHS(), asc); 755 if (!FinishBlock(RHSBlock)) 756 return 0; 757 758 // Create the block that will contain the condition. 759 Block = createBlock(false); 760 761 // See if this is a known constant. 762 const TryResult& KnownVal = TryEvaluateBool(C->getCond()); 763 if (LHSBlock) { 764 AddSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 765 } else { 766 if (KnownVal.isFalse()) { 767 // If we know the condition is false, add NULL as the successor for 768 // the block containing the condition. In this case, the confluence 769 // block will have just one predecessor. 770 AddSuccessor(Block, 0); 771 assert(ConfluenceBlock->pred_size() == 1); 772 } else { 773 // If we have no LHS expression, add the ConfluenceBlock as a direct 774 // successor for the block containing the condition. Moreover, we need to 775 // reverse the order of the predecessors in the ConfluenceBlock because 776 // the RHSBlock will have been added to the succcessors already, and we 777 // want the first predecessor to the the block containing the expression 778 // for the case when the ternary expression evaluates to true. 779 AddSuccessor(Block, ConfluenceBlock); 780 assert(ConfluenceBlock->pred_size() == 2); 781 std::reverse(ConfluenceBlock->pred_begin(), 782 ConfluenceBlock->pred_end()); 783 } 784 } 785 786 AddSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 787 Block->setTerminator(C); 788 return addStmt(C->getCond()); 789} 790 791CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 792 autoCreateBlock(); 793 794 if (DS->isSingleDecl()) { 795 AppendStmt(Block, DS); 796 return VisitDeclSubExpr(DS->getSingleDecl()); 797 } 798 799 CFGBlock *B = 0; 800 801 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 802 typedef llvm::SmallVector<Decl*,10> BufTy; 803 BufTy Buf(DS->decl_begin(), DS->decl_end()); 804 805 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 806 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 807 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 808 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 809 810 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 811 // automatically freed with the CFG. 812 DeclGroupRef DG(*I); 813 Decl *D = *I; 814 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 815 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 816 817 // Append the fake DeclStmt to block. 818 AppendStmt(Block, DSNew); 819 B = VisitDeclSubExpr(D); 820 } 821 822 return B; 823} 824 825/// VisitDeclSubExpr - Utility method to add block-level expressions for 826/// initializers in Decls. 827CFGBlock *CFGBuilder::VisitDeclSubExpr(Decl* D) { 828 assert(Block); 829 830 VarDecl *VD = dyn_cast<VarDecl>(D); 831 832 if (!VD) 833 return Block; 834 835 Expr *Init = VD->getInit(); 836 837 if (Init) { 838 AddStmtChoice::Kind k = 839 VD->getType()->isReferenceType() ? AddStmtChoice::AsLValueNotAlwaysAdd 840 : AddStmtChoice::NotAlwaysAdd; 841 Visit(Init, AddStmtChoice(k)); 842 } 843 844 // If the type of VD is a VLA, then we must process its size expressions. 845 for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0; 846 VA = FindVA(VA->getElementType().getTypePtr())) 847 Block = addStmt(VA->getSizeExpr()); 848 849 return Block; 850} 851 852CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) { 853 // We may see an if statement in the middle of a basic block, or it may be the 854 // first statement we are processing. In either case, we create a new basic 855 // block. First, we create the blocks for the then...else statements, and 856 // then we create the block containing the if statement. If we were in the 857 // middle of a block, we stop processing that block. That block is then the 858 // implicit successor for the "then" and "else" clauses. 859 860 // The block we were proccessing is now finished. Make it the successor 861 // block. 862 if (Block) { 863 Succ = Block; 864 if (!FinishBlock(Block)) 865 return 0; 866 } 867 868 // Process the false branch. 869 CFGBlock* ElseBlock = Succ; 870 871 if (Stmt* Else = I->getElse()) { 872 SaveAndRestore<CFGBlock*> sv(Succ); 873 874 // NULL out Block so that the recursive call to Visit will 875 // create a new basic block. 876 Block = NULL; 877 ElseBlock = addStmt(Else); 878 879 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 880 ElseBlock = sv.get(); 881 else if (Block) { 882 if (!FinishBlock(ElseBlock)) 883 return 0; 884 } 885 } 886 887 // Process the true branch. 888 CFGBlock* ThenBlock; 889 { 890 Stmt* Then = I->getThen(); 891 assert(Then); 892 SaveAndRestore<CFGBlock*> sv(Succ); 893 Block = NULL; 894 ThenBlock = addStmt(Then); 895 896 if (!ThenBlock) { 897 // We can reach here if the "then" body has all NullStmts. 898 // Create an empty block so we can distinguish between true and false 899 // branches in path-sensitive analyses. 900 ThenBlock = createBlock(false); 901 AddSuccessor(ThenBlock, sv.get()); 902 } else if (Block) { 903 if (!FinishBlock(ThenBlock)) 904 return 0; 905 } 906 } 907 908 // Now create a new block containing the if statement. 909 Block = createBlock(false); 910 911 // Set the terminator of the new block to the If statement. 912 Block->setTerminator(I); 913 914 // See if this is a known constant. 915 const TryResult &KnownVal = TryEvaluateBool(I->getCond()); 916 917 // Now add the successors. 918 AddSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 919 AddSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 920 921 // Add the condition as the last statement in the new block. This may create 922 // new blocks as the condition may contain control-flow. Any newly created 923 // blocks will be pointed to be "Block". 924 Block = addStmt(I->getCond()); 925 926 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 927 // and the condition variable initialization to the CFG. 928 if (VarDecl *VD = I->getConditionVariable()) { 929 if (Expr *Init = VD->getInit()) { 930 autoCreateBlock(); 931 AppendStmt(Block, I, AddStmtChoice::AlwaysAdd); 932 addStmt(Init); 933 } 934 } 935 936 return Block; 937} 938 939 940CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) { 941 // If we were in the middle of a block we stop processing that block. 942 // 943 // NOTE: If a "return" appears in the middle of a block, this means that the 944 // code afterwards is DEAD (unreachable). We still keep a basic block 945 // for that code; a simple "mark-and-sweep" from the entry block will be 946 // able to report such dead blocks. 947 if (Block) 948 FinishBlock(Block); 949 950 // Create the new block. 951 Block = createBlock(false); 952 953 // The Exit block is the only successor. 954 AddSuccessor(Block, &cfg->getExit()); 955 956 // Add the return statement to the block. This may create new blocks if R 957 // contains control-flow (short-circuit operations). 958 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 959} 960 961CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) { 962 // Get the block of the labeled statement. Add it to our map. 963 addStmt(L->getSubStmt()); 964 CFGBlock* LabelBlock = Block; 965 966 if (!LabelBlock) // This can happen when the body is empty, i.e. 967 LabelBlock = createBlock(); // scopes that only contains NullStmts. 968 969 assert(LabelMap.find(L) == LabelMap.end() && "label already in map"); 970 LabelMap[ L ] = LabelBlock; 971 972 // Labels partition blocks, so this is the end of the basic block we were 973 // processing (L is the block's label). Because this is label (and we have 974 // already processed the substatement) there is no extra control-flow to worry 975 // about. 976 LabelBlock->setLabel(L); 977 if (!FinishBlock(LabelBlock)) 978 return 0; 979 980 // We set Block to NULL to allow lazy creation of a new block (if necessary); 981 Block = NULL; 982 983 // This block is now the implicit successor of other blocks. 984 Succ = LabelBlock; 985 986 return LabelBlock; 987} 988 989CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) { 990 // Goto is a control-flow statement. Thus we stop processing the current 991 // block and create a new one. 992 if (Block) 993 FinishBlock(Block); 994 995 Block = createBlock(false); 996 Block->setTerminator(G); 997 998 // If we already know the mapping to the label block add the successor now. 999 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 1000 1001 if (I == LabelMap.end()) 1002 // We will need to backpatch this block later. 1003 BackpatchBlocks.push_back(Block); 1004 else 1005 AddSuccessor(Block, I->second); 1006 1007 return Block; 1008} 1009 1010CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) { 1011 CFGBlock* LoopSuccessor = NULL; 1012 1013 // "for" is a control-flow statement. Thus we stop processing the current 1014 // block. 1015 if (Block) { 1016 if (!FinishBlock(Block)) 1017 return 0; 1018 LoopSuccessor = Block; 1019 } else 1020 LoopSuccessor = Succ; 1021 1022 // Save the current value for the break targets. 1023 // All breaks should go to the code following the loop. 1024 SaveAndRestore<CFGBlock*> save_break(BreakTargetBlock); 1025 BreakTargetBlock = LoopSuccessor; 1026 1027 // Because of short-circuit evaluation, the condition of the loop can span 1028 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1029 // evaluate the condition. 1030 CFGBlock* ExitConditionBlock = createBlock(false); 1031 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1032 1033 // Set the terminator for the "exit" condition block. 1034 ExitConditionBlock->setTerminator(F); 1035 1036 // Now add the actual condition to the condition block. Because the condition 1037 // itself may contain control-flow, new blocks may be created. 1038 if (Stmt* C = F->getCond()) { 1039 Block = ExitConditionBlock; 1040 EntryConditionBlock = addStmt(C); 1041 assert(Block == EntryConditionBlock); 1042 1043 // If this block contains a condition variable, add both the condition 1044 // variable and initializer to the CFG. 1045 if (VarDecl *VD = F->getConditionVariable()) { 1046 if (Expr *Init = VD->getInit()) { 1047 autoCreateBlock(); 1048 AppendStmt(Block, F, AddStmtChoice::AlwaysAdd); 1049 EntryConditionBlock = addStmt(Init); 1050 assert(Block == EntryConditionBlock); 1051 } 1052 } 1053 1054 if (Block) { 1055 if (!FinishBlock(EntryConditionBlock)) 1056 return 0; 1057 } 1058 } 1059 1060 // The condition block is the implicit successor for the loop body as well as 1061 // any code above the loop. 1062 Succ = EntryConditionBlock; 1063 1064 // See if this is a known constant. 1065 TryResult KnownVal(true); 1066 1067 if (F->getCond()) 1068 KnownVal = TryEvaluateBool(F->getCond()); 1069 1070 // Now create the loop body. 1071 { 1072 assert(F->getBody()); 1073 1074 // Save the current values for Block, Succ, and continue targets. 1075 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1076 save_continue(ContinueTargetBlock); 1077 1078 // Create a new block to contain the (bottom) of the loop body. 1079 Block = NULL; 1080 1081 if (Stmt* I = F->getInc()) { 1082 // Generate increment code in its own basic block. This is the target of 1083 // continue statements. 1084 Succ = addStmt(I); 1085 } else { 1086 // No increment code. Create a special, empty, block that is used as the 1087 // target block for "looping back" to the start of the loop. 1088 assert(Succ == EntryConditionBlock); 1089 Succ = createBlock(); 1090 } 1091 1092 // Finish up the increment (or empty) block if it hasn't been already. 1093 if (Block) { 1094 assert(Block == Succ); 1095 if (!FinishBlock(Block)) 1096 return 0; 1097 Block = 0; 1098 } 1099 1100 ContinueTargetBlock = Succ; 1101 1102 // The starting block for the loop increment is the block that should 1103 // represent the 'loop target' for looping back to the start of the loop. 1104 ContinueTargetBlock->setLoopTarget(F); 1105 1106 // Now populate the body block, and in the process create new blocks as we 1107 // walk the body of the loop. 1108 CFGBlock* BodyBlock = addStmt(F->getBody()); 1109 1110 if (!BodyBlock) 1111 BodyBlock = ContinueTargetBlock; // can happen for "for (...;...;...) ;" 1112 else if (Block && !FinishBlock(BodyBlock)) 1113 return 0; 1114 1115 // This new body block is a successor to our "exit" condition block. 1116 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1117 } 1118 1119 // Link up the condition block with the code that follows the loop. (the 1120 // false branch). 1121 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1122 1123 // If the loop contains initialization, create a new block for those 1124 // statements. This block can also contain statements that precede the loop. 1125 if (Stmt* I = F->getInit()) { 1126 Block = createBlock(); 1127 return addStmt(I); 1128 } else { 1129 // There is no loop initialization. We are thus basically a while loop. 1130 // NULL out Block to force lazy block construction. 1131 Block = NULL; 1132 Succ = EntryConditionBlock; 1133 return EntryConditionBlock; 1134 } 1135} 1136 1137CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) { 1138 if (asc.alwaysAdd()) { 1139 autoCreateBlock(); 1140 AppendStmt(Block, M, asc); 1141 } 1142 return Visit(M->getBase(), 1143 M->isArrow() ? AddStmtChoice::NotAlwaysAdd 1144 : AddStmtChoice::AsLValueNotAlwaysAdd); 1145} 1146 1147CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) { 1148 // Objective-C fast enumeration 'for' statements: 1149 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1150 // 1151 // for ( Type newVariable in collection_expression ) { statements } 1152 // 1153 // becomes: 1154 // 1155 // prologue: 1156 // 1. collection_expression 1157 // T. jump to loop_entry 1158 // loop_entry: 1159 // 1. side-effects of element expression 1160 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1161 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1162 // TB: 1163 // statements 1164 // T. jump to loop_entry 1165 // FB: 1166 // what comes after 1167 // 1168 // and 1169 // 1170 // Type existingItem; 1171 // for ( existingItem in expression ) { statements } 1172 // 1173 // becomes: 1174 // 1175 // the same with newVariable replaced with existingItem; the binding works 1176 // the same except that for one ObjCForCollectionStmt::getElement() returns 1177 // a DeclStmt and the other returns a DeclRefExpr. 1178 // 1179 1180 CFGBlock* LoopSuccessor = 0; 1181 1182 if (Block) { 1183 if (!FinishBlock(Block)) 1184 return 0; 1185 LoopSuccessor = Block; 1186 Block = 0; 1187 } else 1188 LoopSuccessor = Succ; 1189 1190 // Build the condition blocks. 1191 CFGBlock* ExitConditionBlock = createBlock(false); 1192 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1193 1194 // Set the terminator for the "exit" condition block. 1195 ExitConditionBlock->setTerminator(S); 1196 1197 // The last statement in the block should be the ObjCForCollectionStmt, which 1198 // performs the actual binding to 'element' and determines if there are any 1199 // more items in the collection. 1200 AppendStmt(ExitConditionBlock, S); 1201 Block = ExitConditionBlock; 1202 1203 // Walk the 'element' expression to see if there are any side-effects. We 1204 // generate new blocks as necesary. We DON'T add the statement by default to 1205 // the CFG unless it contains control-flow. 1206 EntryConditionBlock = Visit(S->getElement(), AddStmtChoice::NotAlwaysAdd); 1207 if (Block) { 1208 if (!FinishBlock(EntryConditionBlock)) 1209 return 0; 1210 Block = 0; 1211 } 1212 1213 // The condition block is the implicit successor for the loop body as well as 1214 // any code above the loop. 1215 Succ = EntryConditionBlock; 1216 1217 // Now create the true branch. 1218 { 1219 // Save the current values for Succ, continue and break targets. 1220 SaveAndRestore<CFGBlock*> save_Succ(Succ), 1221 save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 1222 1223 BreakTargetBlock = LoopSuccessor; 1224 ContinueTargetBlock = EntryConditionBlock; 1225 1226 CFGBlock* BodyBlock = addStmt(S->getBody()); 1227 1228 if (!BodyBlock) 1229 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1230 else if (Block) { 1231 if (!FinishBlock(BodyBlock)) 1232 return 0; 1233 } 1234 1235 // This new body block is a successor to our "exit" condition block. 1236 AddSuccessor(ExitConditionBlock, BodyBlock); 1237 } 1238 1239 // Link up the condition block with the code that follows the loop. 1240 // (the false branch). 1241 AddSuccessor(ExitConditionBlock, LoopSuccessor); 1242 1243 // Now create a prologue block to contain the collection expression. 1244 Block = createBlock(); 1245 return addStmt(S->getCollection()); 1246} 1247 1248CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) { 1249 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1250 1251 // Inline the body. 1252 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1253 1254 // The sync body starts its own basic block. This makes it a little easier 1255 // for diagnostic clients. 1256 if (SyncBlock) { 1257 if (!FinishBlock(SyncBlock)) 1258 return 0; 1259 1260 Block = 0; 1261 Succ = SyncBlock; 1262 } 1263 1264 // Inline the sync expression. 1265 return addStmt(S->getSynchExpr()); 1266} 1267 1268CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) { 1269 // FIXME 1270 return NYS(); 1271} 1272 1273CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) { 1274 CFGBlock* LoopSuccessor = NULL; 1275 1276 // "while" is a control-flow statement. Thus we stop processing the current 1277 // block. 1278 if (Block) { 1279 if (!FinishBlock(Block)) 1280 return 0; 1281 LoopSuccessor = Block; 1282 } else 1283 LoopSuccessor = Succ; 1284 1285 // Because of short-circuit evaluation, the condition of the loop can span 1286 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1287 // evaluate the condition. 1288 CFGBlock* ExitConditionBlock = createBlock(false); 1289 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1290 1291 // Set the terminator for the "exit" condition block. 1292 ExitConditionBlock->setTerminator(W); 1293 1294 // Now add the actual condition to the condition block. Because the condition 1295 // itself may contain control-flow, new blocks may be created. Thus we update 1296 // "Succ" after adding the condition. 1297 if (Stmt* C = W->getCond()) { 1298 Block = ExitConditionBlock; 1299 EntryConditionBlock = addStmt(C); 1300 assert(Block == EntryConditionBlock); 1301 1302 // If this block contains a condition variable, add both the condition 1303 // variable and initializer to the CFG. 1304 if (VarDecl *VD = W->getConditionVariable()) { 1305 if (Expr *Init = VD->getInit()) { 1306 autoCreateBlock(); 1307 AppendStmt(Block, W, AddStmtChoice::AlwaysAdd); 1308 EntryConditionBlock = addStmt(Init); 1309 assert(Block == EntryConditionBlock); 1310 } 1311 } 1312 1313 if (Block) { 1314 if (!FinishBlock(EntryConditionBlock)) 1315 return 0; 1316 } 1317 } 1318 1319 // The condition block is the implicit successor for the loop body as well as 1320 // any code above the loop. 1321 Succ = EntryConditionBlock; 1322 1323 // See if this is a known constant. 1324 const TryResult& KnownVal = TryEvaluateBool(W->getCond()); 1325 1326 // Process the loop body. 1327 { 1328 assert(W->getBody()); 1329 1330 // Save the current values for Block, Succ, and continue and break targets 1331 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1332 save_continue(ContinueTargetBlock), 1333 save_break(BreakTargetBlock); 1334 1335 // Create an empty block to represent the transition block for looping back 1336 // to the head of the loop. 1337 Block = 0; 1338 assert(Succ == EntryConditionBlock); 1339 Succ = createBlock(); 1340 Succ->setLoopTarget(W); 1341 ContinueTargetBlock = Succ; 1342 1343 // All breaks should go to the code following the loop. 1344 BreakTargetBlock = LoopSuccessor; 1345 1346 // NULL out Block to force lazy instantiation of blocks for the body. 1347 Block = NULL; 1348 1349 // Create the body. The returned block is the entry to the loop body. 1350 CFGBlock* BodyBlock = addStmt(W->getBody()); 1351 1352 if (!BodyBlock) 1353 BodyBlock = ContinueTargetBlock; // can happen for "while(...) ;" 1354 else if (Block) { 1355 if (!FinishBlock(BodyBlock)) 1356 return 0; 1357 } 1358 1359 // Add the loop body entry as a successor to the condition. 1360 AddSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1361 } 1362 1363 // Link up the condition block with the code that follows the loop. (the 1364 // false branch). 1365 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1366 1367 // There can be no more statements in the condition block since we loop back 1368 // to this block. NULL out Block to force lazy creation of another block. 1369 Block = NULL; 1370 1371 // Return the condition block, which is the dominating block for the loop. 1372 Succ = EntryConditionBlock; 1373 return EntryConditionBlock; 1374} 1375 1376 1377CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 1378 // FIXME: For now we pretend that @catch and the code it contains does not 1379 // exit. 1380 return Block; 1381} 1382 1383CFGBlock* CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt* S) { 1384 // FIXME: This isn't complete. We basically treat @throw like a return 1385 // statement. 1386 1387 // If we were in the middle of a block we stop processing that block. 1388 if (Block && !FinishBlock(Block)) 1389 return 0; 1390 1391 // Create the new block. 1392 Block = createBlock(false); 1393 1394 // The Exit block is the only successor. 1395 AddSuccessor(Block, &cfg->getExit()); 1396 1397 // Add the statement to the block. This may create new blocks if S contains 1398 // control-flow (short-circuit operations). 1399 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 1400} 1401 1402CFGBlock* CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr* T) { 1403 // If we were in the middle of a block we stop processing that block. 1404 if (Block && !FinishBlock(Block)) 1405 return 0; 1406 1407 // Create the new block. 1408 Block = createBlock(false); 1409 1410 if (TryTerminatedBlock) 1411 // The current try statement is the only successor. 1412 AddSuccessor(Block, TryTerminatedBlock); 1413 else 1414 // otherwise the Exit block is the only successor. 1415 AddSuccessor(Block, &cfg->getExit()); 1416 1417 // Add the statement to the block. This may create new blocks if S contains 1418 // control-flow (short-circuit operations). 1419 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 1420} 1421 1422CFGBlock *CFGBuilder::VisitDoStmt(DoStmt* D) { 1423 CFGBlock* LoopSuccessor = NULL; 1424 1425 // "do...while" is a control-flow statement. Thus we stop processing the 1426 // current block. 1427 if (Block) { 1428 if (!FinishBlock(Block)) 1429 return 0; 1430 LoopSuccessor = Block; 1431 } else 1432 LoopSuccessor = Succ; 1433 1434 // Because of short-circuit evaluation, the condition of the loop can span 1435 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1436 // evaluate the condition. 1437 CFGBlock* ExitConditionBlock = createBlock(false); 1438 CFGBlock* EntryConditionBlock = ExitConditionBlock; 1439 1440 // Set the terminator for the "exit" condition block. 1441 ExitConditionBlock->setTerminator(D); 1442 1443 // Now add the actual condition to the condition block. Because the condition 1444 // itself may contain control-flow, new blocks may be created. 1445 if (Stmt* C = D->getCond()) { 1446 Block = ExitConditionBlock; 1447 EntryConditionBlock = addStmt(C); 1448 if (Block) { 1449 if (!FinishBlock(EntryConditionBlock)) 1450 return 0; 1451 } 1452 } 1453 1454 // The condition block is the implicit successor for the loop body. 1455 Succ = EntryConditionBlock; 1456 1457 // See if this is a known constant. 1458 const TryResult &KnownVal = TryEvaluateBool(D->getCond()); 1459 1460 // Process the loop body. 1461 CFGBlock* BodyBlock = NULL; 1462 { 1463 assert(D->getBody()); 1464 1465 // Save the current values for Block, Succ, and continue and break targets 1466 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ), 1467 save_continue(ContinueTargetBlock), 1468 save_break(BreakTargetBlock); 1469 1470 // All continues within this loop should go to the condition block 1471 ContinueTargetBlock = EntryConditionBlock; 1472 1473 // All breaks should go to the code following the loop. 1474 BreakTargetBlock = LoopSuccessor; 1475 1476 // NULL out Block to force lazy instantiation of blocks for the body. 1477 Block = NULL; 1478 1479 // Create the body. The returned block is the entry to the loop body. 1480 BodyBlock = addStmt(D->getBody()); 1481 1482 if (!BodyBlock) 1483 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 1484 else if (Block) { 1485 if (!FinishBlock(BodyBlock)) 1486 return 0; 1487 } 1488 1489 if (!KnownVal.isFalse()) { 1490 // Add an intermediate block between the BodyBlock and the 1491 // ExitConditionBlock to represent the "loop back" transition. Create an 1492 // empty block to represent the transition block for looping back to the 1493 // head of the loop. 1494 // FIXME: Can we do this more efficiently without adding another block? 1495 Block = NULL; 1496 Succ = BodyBlock; 1497 CFGBlock *LoopBackBlock = createBlock(); 1498 LoopBackBlock->setLoopTarget(D); 1499 1500 // Add the loop body entry as a successor to the condition. 1501 AddSuccessor(ExitConditionBlock, LoopBackBlock); 1502 } 1503 else 1504 AddSuccessor(ExitConditionBlock, NULL); 1505 } 1506 1507 // Link up the condition block with the code that follows the loop. 1508 // (the false branch). 1509 AddSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1510 1511 // There can be no more statements in the body block(s) since we loop back to 1512 // the body. NULL out Block to force lazy creation of another block. 1513 Block = NULL; 1514 1515 // Return the loop body, which is the dominating block for the loop. 1516 Succ = BodyBlock; 1517 return BodyBlock; 1518} 1519 1520CFGBlock* CFGBuilder::VisitContinueStmt(ContinueStmt* C) { 1521 // "continue" is a control-flow statement. Thus we stop processing the 1522 // current block. 1523 if (Block && !FinishBlock(Block)) 1524 return 0; 1525 1526 // Now create a new block that ends with the continue statement. 1527 Block = createBlock(false); 1528 Block->setTerminator(C); 1529 1530 // If there is no target for the continue, then we are looking at an 1531 // incomplete AST. This means the CFG cannot be constructed. 1532 if (ContinueTargetBlock) 1533 AddSuccessor(Block, ContinueTargetBlock); 1534 else 1535 badCFG = true; 1536 1537 return Block; 1538} 1539 1540CFGBlock *CFGBuilder::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E, 1541 AddStmtChoice asc) { 1542 1543 if (asc.alwaysAdd()) { 1544 autoCreateBlock(); 1545 AppendStmt(Block, E); 1546 } 1547 1548 // VLA types have expressions that must be evaluated. 1549 if (E->isArgumentType()) { 1550 for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr()); 1551 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1552 addStmt(VA->getSizeExpr()); 1553 } 1554 1555 return Block; 1556} 1557 1558/// VisitStmtExpr - Utility method to handle (nested) statement 1559/// expressions (a GCC extension). 1560CFGBlock* CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 1561 if (asc.alwaysAdd()) { 1562 autoCreateBlock(); 1563 AppendStmt(Block, SE); 1564 } 1565 return VisitCompoundStmt(SE->getSubStmt()); 1566} 1567 1568CFGBlock* CFGBuilder::VisitSwitchStmt(SwitchStmt* Terminator) { 1569 // "switch" is a control-flow statement. Thus we stop processing the current 1570 // block. 1571 CFGBlock* SwitchSuccessor = NULL; 1572 1573 if (Block) { 1574 if (!FinishBlock(Block)) 1575 return 0; 1576 SwitchSuccessor = Block; 1577 } else SwitchSuccessor = Succ; 1578 1579 // Save the current "switch" context. 1580 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 1581 save_break(BreakTargetBlock), 1582 save_default(DefaultCaseBlock); 1583 1584 // Set the "default" case to be the block after the switch statement. If the 1585 // switch statement contains a "default:", this value will be overwritten with 1586 // the block for that code. 1587 DefaultCaseBlock = SwitchSuccessor; 1588 1589 // Create a new block that will contain the switch statement. 1590 SwitchTerminatedBlock = createBlock(false); 1591 1592 // Now process the switch body. The code after the switch is the implicit 1593 // successor. 1594 Succ = SwitchSuccessor; 1595 BreakTargetBlock = SwitchSuccessor; 1596 1597 // When visiting the body, the case statements should automatically get linked 1598 // up to the switch. We also don't keep a pointer to the body, since all 1599 // control-flow from the switch goes to case/default statements. 1600 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 1601 Block = NULL; 1602 CFGBlock *BodyBlock = addStmt(Terminator->getBody()); 1603 if (Block) { 1604 if (!FinishBlock(BodyBlock)) 1605 return 0; 1606 } 1607 1608 // If we have no "default:" case, the default transition is to the code 1609 // following the switch body. 1610 AddSuccessor(SwitchTerminatedBlock, DefaultCaseBlock); 1611 1612 // Add the terminator and condition in the switch block. 1613 SwitchTerminatedBlock->setTerminator(Terminator); 1614 assert(Terminator->getCond() && "switch condition must be non-NULL"); 1615 Block = SwitchTerminatedBlock; 1616 Block = addStmt(Terminator->getCond()); 1617 1618 // Finally, if the SwitchStmt contains a condition variable, add both the 1619 // SwitchStmt and the condition variable initialization to the CFG. 1620 if (VarDecl *VD = Terminator->getConditionVariable()) { 1621 if (Expr *Init = VD->getInit()) { 1622 autoCreateBlock(); 1623 AppendStmt(Block, Terminator, AddStmtChoice::AlwaysAdd); 1624 addStmt(Init); 1625 } 1626 } 1627 1628 return Block; 1629} 1630 1631CFGBlock* CFGBuilder::VisitCaseStmt(CaseStmt* CS) { 1632 // CaseStmts are essentially labels, so they are the first statement in a 1633 // block. 1634 CFGBlock *TopBlock = 0, *LastBlock = 0; 1635 1636 if (Stmt *Sub = CS->getSubStmt()) { 1637 // For deeply nested chains of CaseStmts, instead of doing a recursion 1638 // (which can blow out the stack), manually unroll and create blocks 1639 // along the way. 1640 while (isa<CaseStmt>(Sub)) { 1641 CFGBlock *CurrentBlock = createBlock(false); 1642 CurrentBlock->setLabel(CS); 1643 1644 if (TopBlock) 1645 AddSuccessor(LastBlock, CurrentBlock); 1646 else 1647 TopBlock = CurrentBlock; 1648 1649 AddSuccessor(SwitchTerminatedBlock, CurrentBlock); 1650 LastBlock = CurrentBlock; 1651 1652 CS = cast<CaseStmt>(Sub); 1653 Sub = CS->getSubStmt(); 1654 } 1655 1656 addStmt(Sub); 1657 } 1658 1659 CFGBlock* CaseBlock = Block; 1660 if (!CaseBlock) 1661 CaseBlock = createBlock(); 1662 1663 // Cases statements partition blocks, so this is the top of the basic block we 1664 // were processing (the "case XXX:" is the label). 1665 CaseBlock->setLabel(CS); 1666 1667 if (!FinishBlock(CaseBlock)) 1668 return 0; 1669 1670 // Add this block to the list of successors for the block with the switch 1671 // statement. 1672 assert(SwitchTerminatedBlock); 1673 AddSuccessor(SwitchTerminatedBlock, CaseBlock); 1674 1675 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1676 Block = NULL; 1677 1678 if (TopBlock) { 1679 AddSuccessor(LastBlock, CaseBlock); 1680 Succ = TopBlock; 1681 } 1682 else { 1683 // This block is now the implicit successor of other blocks. 1684 Succ = CaseBlock; 1685 } 1686 1687 return Succ; 1688} 1689 1690CFGBlock* CFGBuilder::VisitDefaultStmt(DefaultStmt* Terminator) { 1691 if (Terminator->getSubStmt()) 1692 addStmt(Terminator->getSubStmt()); 1693 1694 DefaultCaseBlock = Block; 1695 1696 if (!DefaultCaseBlock) 1697 DefaultCaseBlock = createBlock(); 1698 1699 // Default statements partition blocks, so this is the top of the basic block 1700 // we were processing (the "default:" is the label). 1701 DefaultCaseBlock->setLabel(Terminator); 1702 1703 if (!FinishBlock(DefaultCaseBlock)) 1704 return 0; 1705 1706 // Unlike case statements, we don't add the default block to the successors 1707 // for the switch statement immediately. This is done when we finish 1708 // processing the switch statement. This allows for the default case 1709 // (including a fall-through to the code after the switch statement) to always 1710 // be the last successor of a switch-terminated block. 1711 1712 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1713 Block = NULL; 1714 1715 // This block is now the implicit successor of other blocks. 1716 Succ = DefaultCaseBlock; 1717 1718 return DefaultCaseBlock; 1719} 1720 1721CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 1722 // "try"/"catch" is a control-flow statement. Thus we stop processing the 1723 // current block. 1724 CFGBlock* TrySuccessor = NULL; 1725 1726 if (Block) { 1727 if (!FinishBlock(Block)) 1728 return 0; 1729 TrySuccessor = Block; 1730 } else TrySuccessor = Succ; 1731 1732 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 1733 1734 // Create a new block that will contain the try statement. 1735 CFGBlock *NewTryTerminatedBlock = createBlock(false); 1736 // Add the terminator in the try block. 1737 NewTryTerminatedBlock->setTerminator(Terminator); 1738 1739 bool HasCatchAll = false; 1740 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 1741 // The code after the try is the implicit successor. 1742 Succ = TrySuccessor; 1743 CXXCatchStmt *CS = Terminator->getHandler(h); 1744 if (CS->getExceptionDecl() == 0) { 1745 HasCatchAll = true; 1746 } 1747 Block = NULL; 1748 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 1749 if (CatchBlock == 0) 1750 return 0; 1751 // Add this block to the list of successors for the block with the try 1752 // statement. 1753 AddSuccessor(NewTryTerminatedBlock, CatchBlock); 1754 } 1755 if (!HasCatchAll) { 1756 if (PrevTryTerminatedBlock) 1757 AddSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 1758 else 1759 AddSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 1760 } 1761 1762 // The code after the try is the implicit successor. 1763 Succ = TrySuccessor; 1764 1765 // Save the current "try" context. 1766 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock); 1767 TryTerminatedBlock = NewTryTerminatedBlock; 1768 1769 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 1770 Block = NULL; 1771 Block = addStmt(Terminator->getTryBlock()); 1772 return Block; 1773} 1774 1775CFGBlock* CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt* CS) { 1776 // CXXCatchStmt are treated like labels, so they are the first statement in a 1777 // block. 1778 1779 if (CS->getHandlerBlock()) 1780 addStmt(CS->getHandlerBlock()); 1781 1782 CFGBlock* CatchBlock = Block; 1783 if (!CatchBlock) 1784 CatchBlock = createBlock(); 1785 1786 CatchBlock->setLabel(CS); 1787 1788 if (!FinishBlock(CatchBlock)) 1789 return 0; 1790 1791 // We set Block to NULL to allow lazy creation of a new block (if necessary) 1792 Block = NULL; 1793 1794 return CatchBlock; 1795} 1796 1797CFGBlock *CFGBuilder::VisitCXXMemberCallExpr(CXXMemberCallExpr *C, 1798 AddStmtChoice asc) { 1799 AddStmtChoice::Kind K = asc.asLValue() ? AddStmtChoice::AlwaysAddAsLValue 1800 : AddStmtChoice::AlwaysAdd; 1801 autoCreateBlock(); 1802 AppendStmt(Block, C, AddStmtChoice(K)); 1803 return VisitChildren(C); 1804} 1805 1806CFGBlock* CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt* I) { 1807 // Lazily create the indirect-goto dispatch block if there isn't one already. 1808 CFGBlock* IBlock = cfg->getIndirectGotoBlock(); 1809 1810 if (!IBlock) { 1811 IBlock = createBlock(false); 1812 cfg->setIndirectGotoBlock(IBlock); 1813 } 1814 1815 // IndirectGoto is a control-flow statement. Thus we stop processing the 1816 // current block and create a new one. 1817 if (Block && !FinishBlock(Block)) 1818 return 0; 1819 1820 Block = createBlock(false); 1821 Block->setTerminator(I); 1822 AddSuccessor(Block, IBlock); 1823 return addStmt(I->getTarget()); 1824} 1825 1826} // end anonymous namespace 1827 1828/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 1829/// no successors or predecessors. If this is the first block created in the 1830/// CFG, it is automatically set to be the Entry and Exit of the CFG. 1831CFGBlock* CFG::createBlock() { 1832 bool first_block = begin() == end(); 1833 1834 // Create the block. 1835 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 1836 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 1837 Blocks.push_back(Mem, BlkBVC); 1838 1839 // If this is the first block, set it as the Entry and Exit. 1840 if (first_block) 1841 Entry = Exit = &back(); 1842 1843 // Return the block. 1844 return &back(); 1845} 1846 1847/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 1848/// CFG is returned to the caller. 1849CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C, 1850 bool PruneTriviallyFalse, 1851 bool AddEHEdges, bool AddScopes) { 1852 CFGBuilder Builder; 1853 return Builder.buildCFG(D, Statement, C, PruneTriviallyFalse, 1854 AddEHEdges, AddScopes); 1855} 1856 1857//===----------------------------------------------------------------------===// 1858// CFG: Queries for BlkExprs. 1859//===----------------------------------------------------------------------===// 1860 1861namespace { 1862 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 1863} 1864 1865static void FindSubExprAssignments(Stmt *S, 1866 llvm::SmallPtrSet<Expr*,50>& Set) { 1867 if (!S) 1868 return; 1869 1870 for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) { 1871 Stmt *child = *I; 1872 if (!child) 1873 continue; 1874 1875 if (BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 1876 if (B->isAssignmentOp()) Set.insert(B); 1877 1878 FindSubExprAssignments(child, Set); 1879 } 1880} 1881 1882static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 1883 BlkExprMapTy* M = new BlkExprMapTy(); 1884 1885 // Look for assignments that are used as subexpressions. These are the only 1886 // assignments that we want to *possibly* register as a block-level 1887 // expression. Basically, if an assignment occurs both in a subexpression and 1888 // at the block-level, it is a block-level expression. 1889 llvm::SmallPtrSet<Expr*,50> SubExprAssignments; 1890 1891 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 1892 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1893 FindSubExprAssignments(*BI, SubExprAssignments); 1894 1895 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 1896 1897 // Iterate over the statements again on identify the Expr* and Stmt* at the 1898 // block-level that are block-level expressions. 1899 1900 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 1901 if (Expr* Exp = dyn_cast<Expr>(*BI)) { 1902 1903 if (BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 1904 // Assignment expressions that are not nested within another 1905 // expression are really "statements" whose value is never used by 1906 // another expression. 1907 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 1908 continue; 1909 } else if (const StmtExpr* Terminator = dyn_cast<StmtExpr>(Exp)) { 1910 // Special handling for statement expressions. The last statement in 1911 // the statement expression is also a block-level expr. 1912 const CompoundStmt* C = Terminator->getSubStmt(); 1913 if (!C->body_empty()) { 1914 unsigned x = M->size(); 1915 (*M)[C->body_back()] = x; 1916 } 1917 } 1918 1919 unsigned x = M->size(); 1920 (*M)[Exp] = x; 1921 } 1922 1923 // Look at terminators. The condition is a block-level expression. 1924 1925 Stmt* S = (*I)->getTerminatorCondition(); 1926 1927 if (S && M->find(S) == M->end()) { 1928 unsigned x = M->size(); 1929 (*M)[S] = x; 1930 } 1931 } 1932 1933 return M; 1934} 1935 1936CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt* S) { 1937 assert(S != NULL); 1938 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 1939 1940 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 1941 BlkExprMapTy::iterator I = M->find(S); 1942 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 1943} 1944 1945unsigned CFG::getNumBlkExprs() { 1946 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 1947 return M->size(); 1948 else { 1949 // We assume callers interested in the number of BlkExprs will want 1950 // the map constructed if it doesn't already exist. 1951 BlkExprMap = (void*) PopulateBlkExprMap(*this); 1952 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 1953 } 1954} 1955 1956//===----------------------------------------------------------------------===// 1957// Cleanup: CFG dstor. 1958//===----------------------------------------------------------------------===// 1959 1960CFG::~CFG() { 1961 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 1962} 1963 1964//===----------------------------------------------------------------------===// 1965// CFG pretty printing 1966//===----------------------------------------------------------------------===// 1967 1968namespace { 1969 1970class StmtPrinterHelper : public PrinterHelper { 1971 typedef llvm::DenseMap<Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 1972 StmtMapTy StmtMap; 1973 signed CurrentBlock; 1974 unsigned CurrentStmt; 1975 const LangOptions &LangOpts; 1976public: 1977 1978 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 1979 : CurrentBlock(0), CurrentStmt(0), LangOpts(LO) { 1980 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 1981 unsigned j = 1; 1982 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 1983 BI != BEnd; ++BI, ++j ) 1984 StmtMap[*BI] = std::make_pair((*I)->getBlockID(),j); 1985 } 1986 } 1987 1988 virtual ~StmtPrinterHelper() {} 1989 1990 const LangOptions &getLangOpts() const { return LangOpts; } 1991 void setBlockID(signed i) { CurrentBlock = i; } 1992 void setStmtID(unsigned i) { CurrentStmt = i; } 1993 1994 virtual bool handledStmt(Stmt* Terminator, llvm::raw_ostream& OS) { 1995 1996 StmtMapTy::iterator I = StmtMap.find(Terminator); 1997 1998 if (I == StmtMap.end()) 1999 return false; 2000 2001 if (CurrentBlock >= 0 && I->second.first == (unsigned) CurrentBlock 2002 && I->second.second == CurrentStmt) { 2003 return false; 2004 } 2005 2006 OS << "[B" << I->second.first << "." << I->second.second << "]"; 2007 return true; 2008 } 2009}; 2010} // end anonymous namespace 2011 2012 2013namespace { 2014class CFGBlockTerminatorPrint 2015 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 2016 2017 llvm::raw_ostream& OS; 2018 StmtPrinterHelper* Helper; 2019 PrintingPolicy Policy; 2020public: 2021 CFGBlockTerminatorPrint(llvm::raw_ostream& os, StmtPrinterHelper* helper, 2022 const PrintingPolicy &Policy) 2023 : OS(os), Helper(helper), Policy(Policy) {} 2024 2025 void VisitIfStmt(IfStmt* I) { 2026 OS << "if "; 2027 I->getCond()->printPretty(OS,Helper,Policy); 2028 } 2029 2030 // Default case. 2031 void VisitStmt(Stmt* Terminator) { 2032 Terminator->printPretty(OS, Helper, Policy); 2033 } 2034 2035 void VisitForStmt(ForStmt* F) { 2036 OS << "for (" ; 2037 if (F->getInit()) 2038 OS << "..."; 2039 OS << "; "; 2040 if (Stmt* C = F->getCond()) 2041 C->printPretty(OS, Helper, Policy); 2042 OS << "; "; 2043 if (F->getInc()) 2044 OS << "..."; 2045 OS << ")"; 2046 } 2047 2048 void VisitWhileStmt(WhileStmt* W) { 2049 OS << "while " ; 2050 if (Stmt* C = W->getCond()) 2051 C->printPretty(OS, Helper, Policy); 2052 } 2053 2054 void VisitDoStmt(DoStmt* D) { 2055 OS << "do ... while "; 2056 if (Stmt* C = D->getCond()) 2057 C->printPretty(OS, Helper, Policy); 2058 } 2059 2060 void VisitSwitchStmt(SwitchStmt* Terminator) { 2061 OS << "switch "; 2062 Terminator->getCond()->printPretty(OS, Helper, Policy); 2063 } 2064 2065 void VisitCXXTryStmt(CXXTryStmt* CS) { 2066 OS << "try ..."; 2067 } 2068 2069 void VisitConditionalOperator(ConditionalOperator* C) { 2070 C->getCond()->printPretty(OS, Helper, Policy); 2071 OS << " ? ... : ..."; 2072 } 2073 2074 void VisitChooseExpr(ChooseExpr* C) { 2075 OS << "__builtin_choose_expr( "; 2076 C->getCond()->printPretty(OS, Helper, Policy); 2077 OS << " )"; 2078 } 2079 2080 void VisitIndirectGotoStmt(IndirectGotoStmt* I) { 2081 OS << "goto *"; 2082 I->getTarget()->printPretty(OS, Helper, Policy); 2083 } 2084 2085 void VisitBinaryOperator(BinaryOperator* B) { 2086 if (!B->isLogicalOp()) { 2087 VisitExpr(B); 2088 return; 2089 } 2090 2091 B->getLHS()->printPretty(OS, Helper, Policy); 2092 2093 switch (B->getOpcode()) { 2094 case BO_LOr: 2095 OS << " || ..."; 2096 return; 2097 case BO_LAnd: 2098 OS << " && ..."; 2099 return; 2100 default: 2101 assert(false && "Invalid logical operator."); 2102 } 2103 } 2104 2105 void VisitExpr(Expr* E) { 2106 E->printPretty(OS, Helper, Policy); 2107 } 2108}; 2109} // end anonymous namespace 2110 2111 2112static void print_stmt(llvm::raw_ostream &OS, StmtPrinterHelper* Helper, 2113 const CFGElement &E) { 2114 2115 if (E.asStartScope()) { 2116 OS << "start scope\n"; 2117 return; 2118 } 2119 if (E.asEndScope()) { 2120 OS << "end scope\n"; 2121 return; 2122 } 2123 2124 Stmt *S = E; 2125 2126 if (Helper) { 2127 // special printing for statement-expressions. 2128 if (StmtExpr* SE = dyn_cast<StmtExpr>(S)) { 2129 CompoundStmt* Sub = SE->getSubStmt(); 2130 2131 if (Sub->child_begin() != Sub->child_end()) { 2132 OS << "({ ... ; "; 2133 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 2134 OS << " })\n"; 2135 return; 2136 } 2137 } 2138 2139 // special printing for comma expressions. 2140 if (BinaryOperator* B = dyn_cast<BinaryOperator>(S)) { 2141 if (B->getOpcode() == BO_Comma) { 2142 OS << "... , "; 2143 Helper->handledStmt(B->getRHS(),OS); 2144 OS << '\n'; 2145 return; 2146 } 2147 } 2148 } 2149 2150 S->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 2151 2152 if (isa<CXXOperatorCallExpr>(S)) { 2153 OS << " (OperatorCall)"; 2154 } 2155 else if (isa<CXXBindTemporaryExpr>(S)) { 2156 OS << " (BindTemporary)"; 2157 } 2158 2159 2160 // Expressions need a newline. 2161 if (isa<Expr>(S)) 2162 OS << '\n'; 2163} 2164 2165static void print_block(llvm::raw_ostream& OS, const CFG* cfg, 2166 const CFGBlock& B, 2167 StmtPrinterHelper* Helper, bool print_edges) { 2168 2169 if (Helper) Helper->setBlockID(B.getBlockID()); 2170 2171 // Print the header. 2172 OS << "\n [ B" << B.getBlockID(); 2173 2174 if (&B == &cfg->getEntry()) 2175 OS << " (ENTRY) ]\n"; 2176 else if (&B == &cfg->getExit()) 2177 OS << " (EXIT) ]\n"; 2178 else if (&B == cfg->getIndirectGotoBlock()) 2179 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 2180 else 2181 OS << " ]\n"; 2182 2183 // Print the label of this block. 2184 if (Stmt* Label = const_cast<Stmt*>(B.getLabel())) { 2185 2186 if (print_edges) 2187 OS << " "; 2188 2189 if (LabelStmt* L = dyn_cast<LabelStmt>(Label)) 2190 OS << L->getName(); 2191 else if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) { 2192 OS << "case "; 2193 C->getLHS()->printPretty(OS, Helper, 2194 PrintingPolicy(Helper->getLangOpts())); 2195 if (C->getRHS()) { 2196 OS << " ... "; 2197 C->getRHS()->printPretty(OS, Helper, 2198 PrintingPolicy(Helper->getLangOpts())); 2199 } 2200 } else if (isa<DefaultStmt>(Label)) 2201 OS << "default"; 2202 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 2203 OS << "catch ("; 2204 if (CS->getExceptionDecl()) 2205 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 2206 0); 2207 else 2208 OS << "..."; 2209 OS << ")"; 2210 2211 } else 2212 assert(false && "Invalid label statement in CFGBlock."); 2213 2214 OS << ":\n"; 2215 } 2216 2217 // Iterate through the statements in the block and print them. 2218 unsigned j = 1; 2219 2220 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 2221 I != E ; ++I, ++j ) { 2222 2223 // Print the statement # in the basic block and the statement itself. 2224 if (print_edges) 2225 OS << " "; 2226 2227 OS << llvm::format("%3d", j) << ": "; 2228 2229 if (Helper) 2230 Helper->setStmtID(j); 2231 2232 print_stmt(OS,Helper,*I); 2233 } 2234 2235 // Print the terminator of this block. 2236 if (B.getTerminator()) { 2237 if (print_edges) 2238 OS << " "; 2239 2240 OS << " T: "; 2241 2242 if (Helper) Helper->setBlockID(-1); 2243 2244 CFGBlockTerminatorPrint TPrinter(OS, Helper, 2245 PrintingPolicy(Helper->getLangOpts())); 2246 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator())); 2247 OS << '\n'; 2248 } 2249 2250 if (print_edges) { 2251 // Print the predecessors of this block. 2252 OS << " Predecessors (" << B.pred_size() << "):"; 2253 unsigned i = 0; 2254 2255 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 2256 I != E; ++I, ++i) { 2257 2258 if (i == 8 || (i-8) == 0) 2259 OS << "\n "; 2260 2261 OS << " B" << (*I)->getBlockID(); 2262 } 2263 2264 OS << '\n'; 2265 2266 // Print the successors of this block. 2267 OS << " Successors (" << B.succ_size() << "):"; 2268 i = 0; 2269 2270 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 2271 I != E; ++I, ++i) { 2272 2273 if (i == 8 || (i-8) % 10 == 0) 2274 OS << "\n "; 2275 2276 if (*I) 2277 OS << " B" << (*I)->getBlockID(); 2278 else 2279 OS << " NULL"; 2280 } 2281 2282 OS << '\n'; 2283 } 2284} 2285 2286 2287/// dump - A simple pretty printer of a CFG that outputs to stderr. 2288void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 2289 2290/// print - A simple pretty printer of a CFG that outputs to an ostream. 2291void CFG::print(llvm::raw_ostream &OS, const LangOptions &LO) const { 2292 StmtPrinterHelper Helper(this, LO); 2293 2294 // Print the entry block. 2295 print_block(OS, this, getEntry(), &Helper, true); 2296 2297 // Iterate through the CFGBlocks and print them one by one. 2298 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 2299 // Skip the entry block, because we already printed it. 2300 if (&(**I) == &getEntry() || &(**I) == &getExit()) 2301 continue; 2302 2303 print_block(OS, this, **I, &Helper, true); 2304 } 2305 2306 // Print the exit block. 2307 print_block(OS, this, getExit(), &Helper, true); 2308 OS.flush(); 2309} 2310 2311/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 2312void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 2313 print(llvm::errs(), cfg, LO); 2314} 2315 2316/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 2317/// Generally this will only be called from CFG::print. 2318void CFGBlock::print(llvm::raw_ostream& OS, const CFG* cfg, 2319 const LangOptions &LO) const { 2320 StmtPrinterHelper Helper(cfg, LO); 2321 print_block(OS, cfg, *this, &Helper, true); 2322} 2323 2324/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 2325void CFGBlock::printTerminator(llvm::raw_ostream &OS, 2326 const LangOptions &LO) const { 2327 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 2328 TPrinter.Visit(const_cast<Stmt*>(getTerminator())); 2329} 2330 2331Stmt* CFGBlock::getTerminatorCondition() { 2332 2333 if (!Terminator) 2334 return NULL; 2335 2336 Expr* E = NULL; 2337 2338 switch (Terminator->getStmtClass()) { 2339 default: 2340 break; 2341 2342 case Stmt::ForStmtClass: 2343 E = cast<ForStmt>(Terminator)->getCond(); 2344 break; 2345 2346 case Stmt::WhileStmtClass: 2347 E = cast<WhileStmt>(Terminator)->getCond(); 2348 break; 2349 2350 case Stmt::DoStmtClass: 2351 E = cast<DoStmt>(Terminator)->getCond(); 2352 break; 2353 2354 case Stmt::IfStmtClass: 2355 E = cast<IfStmt>(Terminator)->getCond(); 2356 break; 2357 2358 case Stmt::ChooseExprClass: 2359 E = cast<ChooseExpr>(Terminator)->getCond(); 2360 break; 2361 2362 case Stmt::IndirectGotoStmtClass: 2363 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 2364 break; 2365 2366 case Stmt::SwitchStmtClass: 2367 E = cast<SwitchStmt>(Terminator)->getCond(); 2368 break; 2369 2370 case Stmt::ConditionalOperatorClass: 2371 E = cast<ConditionalOperator>(Terminator)->getCond(); 2372 break; 2373 2374 case Stmt::BinaryOperatorClass: // '&&' and '||' 2375 E = cast<BinaryOperator>(Terminator)->getLHS(); 2376 break; 2377 2378 case Stmt::ObjCForCollectionStmtClass: 2379 return Terminator; 2380 } 2381 2382 return E ? E->IgnoreParens() : NULL; 2383} 2384 2385bool CFGBlock::hasBinaryBranchTerminator() const { 2386 2387 if (!Terminator) 2388 return false; 2389 2390 Expr* E = NULL; 2391 2392 switch (Terminator->getStmtClass()) { 2393 default: 2394 return false; 2395 2396 case Stmt::ForStmtClass: 2397 case Stmt::WhileStmtClass: 2398 case Stmt::DoStmtClass: 2399 case Stmt::IfStmtClass: 2400 case Stmt::ChooseExprClass: 2401 case Stmt::ConditionalOperatorClass: 2402 case Stmt::BinaryOperatorClass: 2403 return true; 2404 } 2405 2406 return E ? E->IgnoreParens() : NULL; 2407} 2408 2409 2410//===----------------------------------------------------------------------===// 2411// CFG Graphviz Visualization 2412//===----------------------------------------------------------------------===// 2413 2414 2415#ifndef NDEBUG 2416static StmtPrinterHelper* GraphHelper; 2417#endif 2418 2419void CFG::viewCFG(const LangOptions &LO) const { 2420#ifndef NDEBUG 2421 StmtPrinterHelper H(this, LO); 2422 GraphHelper = &H; 2423 llvm::ViewGraph(this,"CFG"); 2424 GraphHelper = NULL; 2425#endif 2426} 2427 2428namespace llvm { 2429template<> 2430struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 2431 2432 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 2433 2434 static std::string getNodeLabel(const CFGBlock* Node, const CFG* Graph) { 2435 2436#ifndef NDEBUG 2437 std::string OutSStr; 2438 llvm::raw_string_ostream Out(OutSStr); 2439 print_block(Out,Graph, *Node, GraphHelper, false); 2440 std::string& OutStr = Out.str(); 2441 2442 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 2443 2444 // Process string output to make it nicer... 2445 for (unsigned i = 0; i != OutStr.length(); ++i) 2446 if (OutStr[i] == '\n') { // Left justify 2447 OutStr[i] = '\\'; 2448 OutStr.insert(OutStr.begin()+i+1, 'l'); 2449 } 2450 2451 return OutStr; 2452#else 2453 return ""; 2454#endif 2455 } 2456}; 2457} // end namespace llvm 2458