CFG.cpp revision f0e71aede7ccf3e311feac6a414c431f7a0fc3c8
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 "clang/AST/CharUnits.h" 21#include "llvm/Support/GraphWriter.h" 22#include "llvm/Support/Allocator.h" 23#include "llvm/Support/Format.h" 24#include "llvm/ADT/DenseMap.h" 25#include "llvm/ADT/SmallPtrSet.h" 26#include "llvm/ADT/OwningPtr.h" 27 28using namespace clang; 29 30namespace { 31 32static SourceLocation GetEndLoc(Decl *D) { 33 if (VarDecl *VD = dyn_cast<VarDecl>(D)) 34 if (Expr *Ex = VD->getInit()) 35 return Ex->getSourceRange().getEnd(); 36 return D->getLocation(); 37} 38 39class CFGBuilder; 40 41/// The CFG builder uses a recursive algorithm to build the CFG. When 42/// we process an expression, sometimes we know that we must add the 43/// subexpressions as block-level expressions. For example: 44/// 45/// exp1 || exp2 46/// 47/// When processing the '||' expression, we know that exp1 and exp2 48/// need to be added as block-level expressions, even though they 49/// might not normally need to be. AddStmtChoice records this 50/// contextual information. If AddStmtChoice is 'NotAlwaysAdd', then 51/// the builder has an option not to add a subexpression as a 52/// block-level expression. 53/// 54class AddStmtChoice { 55public: 56 enum Kind { NotAlwaysAdd = 0, AlwaysAdd = 1 }; 57 58 AddStmtChoice(Kind a_kind = NotAlwaysAdd) : kind(a_kind) {} 59 60 bool alwaysAdd(CFGBuilder &builder, 61 const Stmt *stmt) const; 62 63 /// Return a copy of this object, except with the 'always-add' bit 64 /// set as specified. 65 AddStmtChoice withAlwaysAdd(bool alwaysAdd) const { 66 return AddStmtChoice(alwaysAdd ? AlwaysAdd : NotAlwaysAdd); 67 } 68 69private: 70 Kind kind; 71}; 72 73/// LocalScope - Node in tree of local scopes created for C++ implicit 74/// destructor calls generation. It contains list of automatic variables 75/// declared in the scope and link to position in previous scope this scope 76/// began in. 77/// 78/// The process of creating local scopes is as follows: 79/// - Init CFGBuilder::ScopePos with invalid position (equivalent for null), 80/// - Before processing statements in scope (e.g. CompoundStmt) create 81/// LocalScope object using CFGBuilder::ScopePos as link to previous scope 82/// and set CFGBuilder::ScopePos to the end of new scope, 83/// - On every occurrence of VarDecl increase CFGBuilder::ScopePos if it points 84/// at this VarDecl, 85/// - For every normal (without jump) end of scope add to CFGBlock destructors 86/// for objects in the current scope, 87/// - For every jump add to CFGBlock destructors for objects 88/// between CFGBuilder::ScopePos and local scope position saved for jump 89/// target. Thanks to C++ restrictions on goto jumps we can be sure that 90/// jump target position will be on the path to root from CFGBuilder::ScopePos 91/// (adding any variable that doesn't need constructor to be called to 92/// LocalScope can break this assumption), 93/// 94class LocalScope { 95public: 96 typedef BumpVector<VarDecl*> AutomaticVarsTy; 97 98 /// const_iterator - Iterates local scope backwards and jumps to previous 99 /// scope on reaching the beginning of currently iterated scope. 100 class const_iterator { 101 const LocalScope* Scope; 102 103 /// VarIter is guaranteed to be greater then 0 for every valid iterator. 104 /// Invalid iterator (with null Scope) has VarIter equal to 0. 105 unsigned VarIter; 106 107 public: 108 /// Create invalid iterator. Dereferencing invalid iterator is not allowed. 109 /// Incrementing invalid iterator is allowed and will result in invalid 110 /// iterator. 111 const_iterator() 112 : Scope(NULL), VarIter(0) {} 113 114 /// Create valid iterator. In case when S.Prev is an invalid iterator and 115 /// I is equal to 0, this will create invalid iterator. 116 const_iterator(const LocalScope& S, unsigned I) 117 : Scope(&S), VarIter(I) { 118 // Iterator to "end" of scope is not allowed. Handle it by going up 119 // in scopes tree possibly up to invalid iterator in the root. 120 if (VarIter == 0 && Scope) 121 *this = Scope->Prev; 122 } 123 124 VarDecl *const* operator->() const { 125 assert (Scope && "Dereferencing invalid iterator is not allowed"); 126 assert (VarIter != 0 && "Iterator has invalid value of VarIter member"); 127 return &Scope->Vars[VarIter - 1]; 128 } 129 VarDecl *operator*() const { 130 return *this->operator->(); 131 } 132 133 const_iterator &operator++() { 134 if (!Scope) 135 return *this; 136 137 assert (VarIter != 0 && "Iterator has invalid value of VarIter member"); 138 --VarIter; 139 if (VarIter == 0) 140 *this = Scope->Prev; 141 return *this; 142 } 143 const_iterator operator++(int) { 144 const_iterator P = *this; 145 ++*this; 146 return P; 147 } 148 149 bool operator==(const const_iterator &rhs) const { 150 return Scope == rhs.Scope && VarIter == rhs.VarIter; 151 } 152 bool operator!=(const const_iterator &rhs) const { 153 return !(*this == rhs); 154 } 155 156 operator bool() const { 157 return *this != const_iterator(); 158 } 159 160 int distance(const_iterator L); 161 }; 162 163 friend class const_iterator; 164 165private: 166 BumpVectorContext ctx; 167 168 /// Automatic variables in order of declaration. 169 AutomaticVarsTy Vars; 170 /// Iterator to variable in previous scope that was declared just before 171 /// begin of this scope. 172 const_iterator Prev; 173 174public: 175 /// Constructs empty scope linked to previous scope in specified place. 176 LocalScope(BumpVectorContext &ctx, const_iterator P) 177 : ctx(ctx), Vars(ctx, 4), Prev(P) {} 178 179 /// Begin of scope in direction of CFG building (backwards). 180 const_iterator begin() const { return const_iterator(*this, Vars.size()); } 181 182 void addVar(VarDecl *VD) { 183 Vars.push_back(VD, ctx); 184 } 185}; 186 187/// distance - Calculates distance from this to L. L must be reachable from this 188/// (with use of ++ operator). Cost of calculating the distance is linear w.r.t. 189/// number of scopes between this and L. 190int LocalScope::const_iterator::distance(LocalScope::const_iterator L) { 191 int D = 0; 192 const_iterator F = *this; 193 while (F.Scope != L.Scope) { 194 assert (F != const_iterator() 195 && "L iterator is not reachable from F iterator."); 196 D += F.VarIter; 197 F = F.Scope->Prev; 198 } 199 D += F.VarIter - L.VarIter; 200 return D; 201} 202 203/// BlockScopePosPair - Structure for specifying position in CFG during its 204/// build process. It consists of CFGBlock that specifies position in CFG graph 205/// and LocalScope::const_iterator that specifies position in LocalScope graph. 206struct BlockScopePosPair { 207 BlockScopePosPair() : block(0) {} 208 BlockScopePosPair(CFGBlock *b, LocalScope::const_iterator scopePos) 209 : block(b), scopePosition(scopePos) {} 210 211 CFGBlock *block; 212 LocalScope::const_iterator scopePosition; 213}; 214 215/// TryResult - a class representing a variant over the values 216/// 'true', 'false', or 'unknown'. This is returned by tryEvaluateBool, 217/// and is used by the CFGBuilder to decide if a branch condition 218/// can be decided up front during CFG construction. 219class TryResult { 220 int X; 221public: 222 TryResult(bool b) : X(b ? 1 : 0) {} 223 TryResult() : X(-1) {} 224 225 bool isTrue() const { return X == 1; } 226 bool isFalse() const { return X == 0; } 227 bool isKnown() const { return X >= 0; } 228 void negate() { 229 assert(isKnown()); 230 X ^= 0x1; 231 } 232}; 233 234/// CFGBuilder - This class implements CFG construction from an AST. 235/// The builder is stateful: an instance of the builder should be used to only 236/// construct a single CFG. 237/// 238/// Example usage: 239/// 240/// CFGBuilder builder; 241/// CFG* cfg = builder.BuildAST(stmt1); 242/// 243/// CFG construction is done via a recursive walk of an AST. We actually parse 244/// the AST in reverse order so that the successor of a basic block is 245/// constructed prior to its predecessor. This allows us to nicely capture 246/// implicit fall-throughs without extra basic blocks. 247/// 248class CFGBuilder { 249 typedef BlockScopePosPair JumpTarget; 250 typedef BlockScopePosPair JumpSource; 251 252 ASTContext *Context; 253 llvm::OwningPtr<CFG> cfg; 254 255 CFGBlock *Block; 256 CFGBlock *Succ; 257 JumpTarget ContinueJumpTarget; 258 JumpTarget BreakJumpTarget; 259 CFGBlock *SwitchTerminatedBlock; 260 CFGBlock *DefaultCaseBlock; 261 CFGBlock *TryTerminatedBlock; 262 263 // Current position in local scope. 264 LocalScope::const_iterator ScopePos; 265 266 // LabelMap records the mapping from Label expressions to their jump targets. 267 typedef llvm::DenseMap<LabelDecl*, JumpTarget> LabelMapTy; 268 LabelMapTy LabelMap; 269 270 // A list of blocks that end with a "goto" that must be backpatched to their 271 // resolved targets upon completion of CFG construction. 272 typedef std::vector<JumpSource> BackpatchBlocksTy; 273 BackpatchBlocksTy BackpatchBlocks; 274 275 // A list of labels whose address has been taken (for indirect gotos). 276 typedef llvm::SmallPtrSet<LabelDecl*, 5> LabelSetTy; 277 LabelSetTy AddressTakenLabels; 278 279 bool badCFG; 280 const CFG::BuildOptions &BuildOpts; 281 282 // State to track for building switch statements. 283 bool switchExclusivelyCovered; 284 Expr::EvalResult *switchCond; 285 286 CFG::BuildOptions::ForcedBlkExprs::value_type *cachedEntry; 287 const Stmt *lastLookup; 288 289public: 290 explicit CFGBuilder(ASTContext *astContext, 291 const CFG::BuildOptions &buildOpts) 292 : Context(astContext), cfg(new CFG()), // crew a new CFG 293 Block(NULL), Succ(NULL), 294 SwitchTerminatedBlock(NULL), DefaultCaseBlock(NULL), 295 TryTerminatedBlock(NULL), badCFG(false), BuildOpts(buildOpts), 296 switchExclusivelyCovered(false), switchCond(0), 297 cachedEntry(0), lastLookup(0) {} 298 299 // buildCFG - Used by external clients to construct the CFG. 300 CFG* buildCFG(const Decl *D, Stmt *Statement); 301 302 bool alwaysAdd(const Stmt *stmt); 303 304private: 305 // Visitors to walk an AST and construct the CFG. 306 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc); 307 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc); 308 CFGBlock *VisitBlockExpr(BlockExpr *E, AddStmtChoice asc); 309 CFGBlock *VisitBreakStmt(BreakStmt *B); 310 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S); 311 CFGBlock *VisitExprWithCleanups(ExprWithCleanups *E, 312 AddStmtChoice asc); 313 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T); 314 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S); 315 CFGBlock *VisitCXXForRangeStmt(CXXForRangeStmt *S); 316 CFGBlock *VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E, 317 AddStmtChoice asc); 318 CFGBlock *VisitCXXConstructExpr(CXXConstructExpr *C, AddStmtChoice asc); 319 CFGBlock *VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E, 320 AddStmtChoice asc); 321 CFGBlock *VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C, 322 AddStmtChoice asc); 323 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc); 324 CFGBlock *VisitCaseStmt(CaseStmt *C); 325 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc); 326 CFGBlock *VisitCompoundStmt(CompoundStmt *C); 327 CFGBlock *VisitConditionalOperator(AbstractConditionalOperator *C, 328 AddStmtChoice asc); 329 CFGBlock *VisitContinueStmt(ContinueStmt *C); 330 CFGBlock *VisitDeclStmt(DeclStmt *DS); 331 CFGBlock *VisitDeclSubExpr(DeclStmt *DS); 332 CFGBlock *VisitDefaultStmt(DefaultStmt *D); 333 CFGBlock *VisitDoStmt(DoStmt *D); 334 CFGBlock *VisitForStmt(ForStmt *F); 335 CFGBlock *VisitGotoStmt(GotoStmt *G); 336 CFGBlock *VisitIfStmt(IfStmt *I); 337 CFGBlock *VisitImplicitCastExpr(ImplicitCastExpr *E, AddStmtChoice asc); 338 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I); 339 CFGBlock *VisitLabelStmt(LabelStmt *L); 340 CFGBlock *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc); 341 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S); 342 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S); 343 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S); 344 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S); 345 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S); 346 CFGBlock *VisitReturnStmt(ReturnStmt *R); 347 CFGBlock *VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E, 348 AddStmtChoice asc); 349 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc); 350 CFGBlock *VisitSwitchStmt(SwitchStmt *S); 351 CFGBlock *VisitUnaryOperator(UnaryOperator *U, AddStmtChoice asc); 352 CFGBlock *VisitWhileStmt(WhileStmt *W); 353 354 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd); 355 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc); 356 CFGBlock *VisitChildren(Stmt *S); 357 358 // Visitors to walk an AST and generate destructors of temporaries in 359 // full expression. 360 CFGBlock *VisitForTemporaryDtors(Stmt *E, bool BindToTemporary = false); 361 CFGBlock *VisitChildrenForTemporaryDtors(Stmt *E); 362 CFGBlock *VisitBinaryOperatorForTemporaryDtors(BinaryOperator *E); 363 CFGBlock *VisitCXXBindTemporaryExprForTemporaryDtors(CXXBindTemporaryExpr *E, 364 bool BindToTemporary); 365 CFGBlock * 366 VisitConditionalOperatorForTemporaryDtors(AbstractConditionalOperator *E, 367 bool BindToTemporary); 368 369 // NYS == Not Yet Supported 370 CFGBlock *NYS() { 371 badCFG = true; 372 return Block; 373 } 374 375 void autoCreateBlock() { if (!Block) Block = createBlock(); } 376 CFGBlock *createBlock(bool add_successor = true); 377 378 CFGBlock *addStmt(Stmt *S) { 379 return Visit(S, AddStmtChoice::AlwaysAdd); 380 } 381 CFGBlock *addInitializer(CXXCtorInitializer *I); 382 void addAutomaticObjDtors(LocalScope::const_iterator B, 383 LocalScope::const_iterator E, Stmt *S); 384 void addImplicitDtorsForDestructor(const CXXDestructorDecl *DD); 385 386 // Local scopes creation. 387 LocalScope* createOrReuseLocalScope(LocalScope* Scope); 388 389 void addLocalScopeForStmt(Stmt *S); 390 LocalScope* addLocalScopeForDeclStmt(DeclStmt *DS, LocalScope* Scope = NULL); 391 LocalScope* addLocalScopeForVarDecl(VarDecl *VD, LocalScope* Scope = NULL); 392 393 void addLocalScopeAndDtors(Stmt *S); 394 395 // Interface to CFGBlock - adding CFGElements. 396 void appendStmt(CFGBlock *B, const Stmt *S) { 397 if (alwaysAdd(S) && cachedEntry) 398 cachedEntry->second = B; 399 400 // All block-level expressions should have already been IgnoreParens()ed. 401 assert(!isa<Expr>(S) || cast<Expr>(S)->IgnoreParens() == S); 402 B->appendStmt(const_cast<Stmt*>(S), cfg->getBumpVectorContext()); 403 } 404 void appendInitializer(CFGBlock *B, CXXCtorInitializer *I) { 405 B->appendInitializer(I, cfg->getBumpVectorContext()); 406 } 407 void appendBaseDtor(CFGBlock *B, const CXXBaseSpecifier *BS) { 408 B->appendBaseDtor(BS, cfg->getBumpVectorContext()); 409 } 410 void appendMemberDtor(CFGBlock *B, FieldDecl *FD) { 411 B->appendMemberDtor(FD, cfg->getBumpVectorContext()); 412 } 413 void appendTemporaryDtor(CFGBlock *B, CXXBindTemporaryExpr *E) { 414 B->appendTemporaryDtor(E, cfg->getBumpVectorContext()); 415 } 416 417 void insertAutomaticObjDtors(CFGBlock *Blk, CFGBlock::iterator I, 418 LocalScope::const_iterator B, LocalScope::const_iterator E, Stmt *S); 419 void appendAutomaticObjDtors(CFGBlock *Blk, LocalScope::const_iterator B, 420 LocalScope::const_iterator E, Stmt *S); 421 void prependAutomaticObjDtorsWithTerminator(CFGBlock *Blk, 422 LocalScope::const_iterator B, LocalScope::const_iterator E); 423 424 void addSuccessor(CFGBlock *B, CFGBlock *S) { 425 B->addSuccessor(S, cfg->getBumpVectorContext()); 426 } 427 428 /// Try and evaluate an expression to an integer constant. 429 bool tryEvaluate(Expr *S, Expr::EvalResult &outResult) { 430 if (!BuildOpts.PruneTriviallyFalseEdges) 431 return false; 432 return !S->isTypeDependent() && 433 !S->isValueDependent() && 434 S->Evaluate(outResult, *Context); 435 } 436 437 /// tryEvaluateBool - Try and evaluate the Stmt and return 0 or 1 438 /// if we can evaluate to a known value, otherwise return -1. 439 TryResult tryEvaluateBool(Expr *S) { 440 Expr::EvalResult Result; 441 if (!tryEvaluate(S, Result)) 442 return TryResult(); 443 444 if (Result.Val.isInt()) 445 return Result.Val.getInt().getBoolValue(); 446 447 if (Result.Val.isLValue()) { 448 const Expr *e = Result.Val.getLValueBase(); 449 const CharUnits &c = Result.Val.getLValueOffset(); 450 if (!e && c.isZero()) 451 return false; 452 } 453 return TryResult(); 454 } 455 456}; 457 458inline bool AddStmtChoice::alwaysAdd(CFGBuilder &builder, 459 const Stmt *stmt) const { 460 return builder.alwaysAdd(stmt) || kind == AlwaysAdd; 461} 462 463bool CFGBuilder::alwaysAdd(const Stmt *stmt) { 464 bool shouldAdd = BuildOpts.alwaysAdd(stmt); 465 466 if (!BuildOpts.forcedBlkExprs) 467 return shouldAdd; 468 469 if (lastLookup == stmt) { 470 if (cachedEntry) { 471 assert(cachedEntry->first == stmt); 472 return true; 473 } 474 return shouldAdd; 475 } 476 477 lastLookup = stmt; 478 479 // Perform the lookup! 480 CFG::BuildOptions::ForcedBlkExprs *fb = *BuildOpts.forcedBlkExprs; 481 482 if (!fb) { 483 // No need to update 'cachedEntry', since it will always be null. 484 assert(cachedEntry == 0); 485 return shouldAdd; 486 } 487 488 CFG::BuildOptions::ForcedBlkExprs::iterator itr = fb->find(stmt); 489 if (itr == fb->end()) { 490 cachedEntry = 0; 491 return shouldAdd; 492 } 493 494 cachedEntry = &*itr; 495 return true; 496} 497 498// FIXME: Add support for dependent-sized array types in C++? 499// Does it even make sense to build a CFG for an uninstantiated template? 500static const VariableArrayType *FindVA(const Type *t) { 501 while (const ArrayType *vt = dyn_cast<ArrayType>(t)) { 502 if (const VariableArrayType *vat = dyn_cast<VariableArrayType>(vt)) 503 if (vat->getSizeExpr()) 504 return vat; 505 506 t = vt->getElementType().getTypePtr(); 507 } 508 509 return 0; 510} 511 512/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an 513/// arbitrary statement. Examples include a single expression or a function 514/// body (compound statement). The ownership of the returned CFG is 515/// transferred to the caller. If CFG construction fails, this method returns 516/// NULL. 517CFG* CFGBuilder::buildCFG(const Decl *D, Stmt *Statement) { 518 assert(cfg.get()); 519 if (!Statement) 520 return NULL; 521 522 // Create an empty block that will serve as the exit block for the CFG. Since 523 // this is the first block added to the CFG, it will be implicitly registered 524 // as the exit block. 525 Succ = createBlock(); 526 assert(Succ == &cfg->getExit()); 527 Block = NULL; // the EXIT block is empty. Create all other blocks lazily. 528 529 if (BuildOpts.AddImplicitDtors) 530 if (const CXXDestructorDecl *DD = dyn_cast_or_null<CXXDestructorDecl>(D)) 531 addImplicitDtorsForDestructor(DD); 532 533 // Visit the statements and create the CFG. 534 CFGBlock *B = addStmt(Statement); 535 536 if (badCFG) 537 return NULL; 538 539 // For C++ constructor add initializers to CFG. 540 if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) { 541 for (CXXConstructorDecl::init_const_reverse_iterator I = CD->init_rbegin(), 542 E = CD->init_rend(); I != E; ++I) { 543 B = addInitializer(*I); 544 if (badCFG) 545 return NULL; 546 } 547 } 548 549 if (B) 550 Succ = B; 551 552 // Backpatch the gotos whose label -> block mappings we didn't know when we 553 // encountered them. 554 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 555 E = BackpatchBlocks.end(); I != E; ++I ) { 556 557 CFGBlock *B = I->block; 558 GotoStmt *G = cast<GotoStmt>(B->getTerminator()); 559 LabelMapTy::iterator LI = LabelMap.find(G->getLabel()); 560 561 // If there is no target for the goto, then we are looking at an 562 // incomplete AST. Handle this by not registering a successor. 563 if (LI == LabelMap.end()) continue; 564 565 JumpTarget JT = LI->second; 566 prependAutomaticObjDtorsWithTerminator(B, I->scopePosition, 567 JT.scopePosition); 568 addSuccessor(B, JT.block); 569 } 570 571 // Add successors to the Indirect Goto Dispatch block (if we have one). 572 if (CFGBlock *B = cfg->getIndirectGotoBlock()) 573 for (LabelSetTy::iterator I = AddressTakenLabels.begin(), 574 E = AddressTakenLabels.end(); I != E; ++I ) { 575 576 // Lookup the target block. 577 LabelMapTy::iterator LI = LabelMap.find(*I); 578 579 // If there is no target block that contains label, then we are looking 580 // at an incomplete AST. Handle this by not registering a successor. 581 if (LI == LabelMap.end()) continue; 582 583 addSuccessor(B, LI->second.block); 584 } 585 586 // Create an empty entry block that has no predecessors. 587 cfg->setEntry(createBlock()); 588 589 return cfg.take(); 590} 591 592/// createBlock - Used to lazily create blocks that are connected 593/// to the current (global) succcessor. 594CFGBlock *CFGBuilder::createBlock(bool add_successor) { 595 CFGBlock *B = cfg->createBlock(); 596 if (add_successor && Succ) 597 addSuccessor(B, Succ); 598 return B; 599} 600 601/// addInitializer - Add C++ base or member initializer element to CFG. 602CFGBlock *CFGBuilder::addInitializer(CXXCtorInitializer *I) { 603 if (!BuildOpts.AddInitializers) 604 return Block; 605 606 bool IsReference = false; 607 bool HasTemporaries = false; 608 609 // Destructors of temporaries in initialization expression should be called 610 // after initialization finishes. 611 Expr *Init = I->getInit(); 612 if (Init) { 613 if (FieldDecl *FD = I->getAnyMember()) 614 IsReference = FD->getType()->isReferenceType(); 615 HasTemporaries = isa<ExprWithCleanups>(Init); 616 617 if (BuildOpts.AddImplicitDtors && HasTemporaries) { 618 // Generate destructors for temporaries in initialization expression. 619 VisitForTemporaryDtors(cast<ExprWithCleanups>(Init)->getSubExpr(), 620 IsReference); 621 } 622 } 623 624 autoCreateBlock(); 625 appendInitializer(Block, I); 626 627 if (Init) { 628 if (HasTemporaries) { 629 // For expression with temporaries go directly to subexpression to omit 630 // generating destructors for the second time. 631 return Visit(cast<ExprWithCleanups>(Init)->getSubExpr()); 632 } 633 return Visit(Init); 634 } 635 636 return Block; 637} 638 639/// addAutomaticObjDtors - Add to current block automatic objects destructors 640/// for objects in range of local scope positions. Use S as trigger statement 641/// for destructors. 642void CFGBuilder::addAutomaticObjDtors(LocalScope::const_iterator B, 643 LocalScope::const_iterator E, Stmt *S) { 644 if (!BuildOpts.AddImplicitDtors) 645 return; 646 647 if (B == E) 648 return; 649 650 autoCreateBlock(); 651 appendAutomaticObjDtors(Block, B, E, S); 652} 653 654/// addImplicitDtorsForDestructor - Add implicit destructors generated for 655/// base and member objects in destructor. 656void CFGBuilder::addImplicitDtorsForDestructor(const CXXDestructorDecl *DD) { 657 assert (BuildOpts.AddImplicitDtors 658 && "Can be called only when dtors should be added"); 659 const CXXRecordDecl *RD = DD->getParent(); 660 661 // At the end destroy virtual base objects. 662 for (CXXRecordDecl::base_class_const_iterator VI = RD->vbases_begin(), 663 VE = RD->vbases_end(); VI != VE; ++VI) { 664 const CXXRecordDecl *CD = VI->getType()->getAsCXXRecordDecl(); 665 if (!CD->hasTrivialDestructor()) { 666 autoCreateBlock(); 667 appendBaseDtor(Block, VI); 668 } 669 } 670 671 // Before virtual bases destroy direct base objects. 672 for (CXXRecordDecl::base_class_const_iterator BI = RD->bases_begin(), 673 BE = RD->bases_end(); BI != BE; ++BI) { 674 if (!BI->isVirtual()) { 675 const CXXRecordDecl *CD = BI->getType()->getAsCXXRecordDecl(); 676 if (!CD->hasTrivialDestructor()) { 677 autoCreateBlock(); 678 appendBaseDtor(Block, BI); 679 } 680 } 681 } 682 683 // First destroy member objects. 684 for (CXXRecordDecl::field_iterator FI = RD->field_begin(), 685 FE = RD->field_end(); FI != FE; ++FI) { 686 // Check for constant size array. Set type to array element type. 687 QualType QT = FI->getType(); 688 if (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) { 689 if (AT->getSize() == 0) 690 continue; 691 QT = AT->getElementType(); 692 } 693 694 if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl()) 695 if (!CD->hasTrivialDestructor()) { 696 autoCreateBlock(); 697 appendMemberDtor(Block, *FI); 698 } 699 } 700} 701 702/// createOrReuseLocalScope - If Scope is NULL create new LocalScope. Either 703/// way return valid LocalScope object. 704LocalScope* CFGBuilder::createOrReuseLocalScope(LocalScope* Scope) { 705 if (!Scope) { 706 llvm::BumpPtrAllocator &alloc = cfg->getAllocator(); 707 Scope = alloc.Allocate<LocalScope>(); 708 BumpVectorContext ctx(alloc); 709 new (Scope) LocalScope(ctx, ScopePos); 710 } 711 return Scope; 712} 713 714/// addLocalScopeForStmt - Add LocalScope to local scopes tree for statement 715/// that should create implicit scope (e.g. if/else substatements). 716void CFGBuilder::addLocalScopeForStmt(Stmt *S) { 717 if (!BuildOpts.AddImplicitDtors) 718 return; 719 720 LocalScope *Scope = 0; 721 722 // For compound statement we will be creating explicit scope. 723 if (CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) { 724 for (CompoundStmt::body_iterator BI = CS->body_begin(), BE = CS->body_end() 725 ; BI != BE; ++BI) { 726 Stmt *SI = *BI; 727 if (LabelStmt *LS = dyn_cast<LabelStmt>(SI)) 728 SI = LS->getSubStmt(); 729 if (DeclStmt *DS = dyn_cast<DeclStmt>(SI)) 730 Scope = addLocalScopeForDeclStmt(DS, Scope); 731 } 732 return; 733 } 734 735 // For any other statement scope will be implicit and as such will be 736 // interesting only for DeclStmt. 737 if (LabelStmt *LS = dyn_cast<LabelStmt>(S)) 738 S = LS->getSubStmt(); 739 if (DeclStmt *DS = dyn_cast<DeclStmt>(S)) 740 addLocalScopeForDeclStmt(DS); 741} 742 743/// addLocalScopeForDeclStmt - Add LocalScope for declaration statement. Will 744/// reuse Scope if not NULL. 745LocalScope* CFGBuilder::addLocalScopeForDeclStmt(DeclStmt *DS, 746 LocalScope* Scope) { 747 if (!BuildOpts.AddImplicitDtors) 748 return Scope; 749 750 for (DeclStmt::decl_iterator DI = DS->decl_begin(), DE = DS->decl_end() 751 ; DI != DE; ++DI) { 752 if (VarDecl *VD = dyn_cast<VarDecl>(*DI)) 753 Scope = addLocalScopeForVarDecl(VD, Scope); 754 } 755 return Scope; 756} 757 758/// addLocalScopeForVarDecl - Add LocalScope for variable declaration. It will 759/// create add scope for automatic objects and temporary objects bound to 760/// const reference. Will reuse Scope if not NULL. 761LocalScope* CFGBuilder::addLocalScopeForVarDecl(VarDecl *VD, 762 LocalScope* Scope) { 763 if (!BuildOpts.AddImplicitDtors) 764 return Scope; 765 766 // Check if variable is local. 767 switch (VD->getStorageClass()) { 768 case SC_None: 769 case SC_Auto: 770 case SC_Register: 771 break; 772 default: return Scope; 773 } 774 775 // Check for const references bound to temporary. Set type to pointee. 776 QualType QT = VD->getType(); 777 if (const ReferenceType* RT = QT.getTypePtr()->getAs<ReferenceType>()) { 778 QT = RT->getPointeeType(); 779 if (!QT.isConstQualified()) 780 return Scope; 781 if (!VD->extendsLifetimeOfTemporary()) 782 return Scope; 783 } 784 785 // Check for constant size array. Set type to array element type. 786 if (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) { 787 if (AT->getSize() == 0) 788 return Scope; 789 QT = AT->getElementType(); 790 } 791 792 // Check if type is a C++ class with non-trivial destructor. 793 if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl()) 794 if (!CD->hasTrivialDestructor()) { 795 // Add the variable to scope 796 Scope = createOrReuseLocalScope(Scope); 797 Scope->addVar(VD); 798 ScopePos = Scope->begin(); 799 } 800 return Scope; 801} 802 803/// addLocalScopeAndDtors - For given statement add local scope for it and 804/// add destructors that will cleanup the scope. Will reuse Scope if not NULL. 805void CFGBuilder::addLocalScopeAndDtors(Stmt *S) { 806 if (!BuildOpts.AddImplicitDtors) 807 return; 808 809 LocalScope::const_iterator scopeBeginPos = ScopePos; 810 addLocalScopeForStmt(S); 811 addAutomaticObjDtors(ScopePos, scopeBeginPos, S); 812} 813 814/// insertAutomaticObjDtors - Insert destructor CFGElements for variables with 815/// automatic storage duration to CFGBlock's elements vector. Insertion will be 816/// performed in place specified with iterator. 817void CFGBuilder::insertAutomaticObjDtors(CFGBlock *Blk, CFGBlock::iterator I, 818 LocalScope::const_iterator B, LocalScope::const_iterator E, Stmt *S) { 819 BumpVectorContext &C = cfg->getBumpVectorContext(); 820 I = Blk->beginAutomaticObjDtorsInsert(I, B.distance(E), C); 821 while (B != E) 822 I = Blk->insertAutomaticObjDtor(I, *B++, S); 823} 824 825/// appendAutomaticObjDtors - Append destructor CFGElements for variables with 826/// automatic storage duration to CFGBlock's elements vector. Elements will be 827/// appended to physical end of the vector which happens to be logical 828/// beginning. 829void CFGBuilder::appendAutomaticObjDtors(CFGBlock *Blk, 830 LocalScope::const_iterator B, LocalScope::const_iterator E, Stmt *S) { 831 insertAutomaticObjDtors(Blk, Blk->begin(), B, E, S); 832} 833 834/// prependAutomaticObjDtorsWithTerminator - Prepend destructor CFGElements for 835/// variables with automatic storage duration to CFGBlock's elements vector. 836/// Elements will be prepended to physical beginning of the vector which 837/// happens to be logical end. Use blocks terminator as statement that specifies 838/// destructors call site. 839void CFGBuilder::prependAutomaticObjDtorsWithTerminator(CFGBlock *Blk, 840 LocalScope::const_iterator B, LocalScope::const_iterator E) { 841 insertAutomaticObjDtors(Blk, Blk->end(), B, E, Blk->getTerminator()); 842} 843 844/// Visit - Walk the subtree of a statement and add extra 845/// blocks for ternary operators, &&, and ||. We also process "," and 846/// DeclStmts (which may contain nested control-flow). 847CFGBlock *CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) { 848 if (!S) { 849 badCFG = true; 850 return 0; 851 } 852 853 if (Expr *E = dyn_cast<Expr>(S)) 854 S = E->IgnoreParens(); 855 856 switch (S->getStmtClass()) { 857 default: 858 return VisitStmt(S, asc); 859 860 case Stmt::AddrLabelExprClass: 861 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc); 862 863 case Stmt::BinaryConditionalOperatorClass: 864 return VisitConditionalOperator(cast<BinaryConditionalOperator>(S), asc); 865 866 case Stmt::BinaryOperatorClass: 867 return VisitBinaryOperator(cast<BinaryOperator>(S), asc); 868 869 case Stmt::BlockExprClass: 870 return VisitBlockExpr(cast<BlockExpr>(S), asc); 871 872 case Stmt::BreakStmtClass: 873 return VisitBreakStmt(cast<BreakStmt>(S)); 874 875 case Stmt::CallExprClass: 876 case Stmt::CXXOperatorCallExprClass: 877 case Stmt::CXXMemberCallExprClass: 878 return VisitCallExpr(cast<CallExpr>(S), asc); 879 880 case Stmt::CaseStmtClass: 881 return VisitCaseStmt(cast<CaseStmt>(S)); 882 883 case Stmt::ChooseExprClass: 884 return VisitChooseExpr(cast<ChooseExpr>(S), asc); 885 886 case Stmt::CompoundStmtClass: 887 return VisitCompoundStmt(cast<CompoundStmt>(S)); 888 889 case Stmt::ConditionalOperatorClass: 890 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc); 891 892 case Stmt::ContinueStmtClass: 893 return VisitContinueStmt(cast<ContinueStmt>(S)); 894 895 case Stmt::CXXCatchStmtClass: 896 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S)); 897 898 case Stmt::ExprWithCleanupsClass: 899 return VisitExprWithCleanups(cast<ExprWithCleanups>(S), asc); 900 901 case Stmt::CXXBindTemporaryExprClass: 902 return VisitCXXBindTemporaryExpr(cast<CXXBindTemporaryExpr>(S), asc); 903 904 case Stmt::CXXConstructExprClass: 905 return VisitCXXConstructExpr(cast<CXXConstructExpr>(S), asc); 906 907 case Stmt::CXXFunctionalCastExprClass: 908 return VisitCXXFunctionalCastExpr(cast<CXXFunctionalCastExpr>(S), asc); 909 910 case Stmt::CXXTemporaryObjectExprClass: 911 return VisitCXXTemporaryObjectExpr(cast<CXXTemporaryObjectExpr>(S), asc); 912 913 case Stmt::CXXThrowExprClass: 914 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S)); 915 916 case Stmt::CXXTryStmtClass: 917 return VisitCXXTryStmt(cast<CXXTryStmt>(S)); 918 919 case Stmt::CXXForRangeStmtClass: 920 return VisitCXXForRangeStmt(cast<CXXForRangeStmt>(S)); 921 922 case Stmt::DeclStmtClass: 923 return VisitDeclStmt(cast<DeclStmt>(S)); 924 925 case Stmt::DefaultStmtClass: 926 return VisitDefaultStmt(cast<DefaultStmt>(S)); 927 928 case Stmt::DoStmtClass: 929 return VisitDoStmt(cast<DoStmt>(S)); 930 931 case Stmt::ForStmtClass: 932 return VisitForStmt(cast<ForStmt>(S)); 933 934 case Stmt::GotoStmtClass: 935 return VisitGotoStmt(cast<GotoStmt>(S)); 936 937 case Stmt::IfStmtClass: 938 return VisitIfStmt(cast<IfStmt>(S)); 939 940 case Stmt::ImplicitCastExprClass: 941 return VisitImplicitCastExpr(cast<ImplicitCastExpr>(S), asc); 942 943 case Stmt::IndirectGotoStmtClass: 944 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S)); 945 946 case Stmt::LabelStmtClass: 947 return VisitLabelStmt(cast<LabelStmt>(S)); 948 949 case Stmt::MemberExprClass: 950 return VisitMemberExpr(cast<MemberExpr>(S), asc); 951 952 case Stmt::ObjCAtCatchStmtClass: 953 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S)); 954 955 case Stmt::ObjCAtSynchronizedStmtClass: 956 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S)); 957 958 case Stmt::ObjCAtThrowStmtClass: 959 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S)); 960 961 case Stmt::ObjCAtTryStmtClass: 962 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S)); 963 964 case Stmt::ObjCForCollectionStmtClass: 965 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S)); 966 967 case Stmt::NullStmtClass: 968 return Block; 969 970 case Stmt::ReturnStmtClass: 971 return VisitReturnStmt(cast<ReturnStmt>(S)); 972 973 case Stmt::UnaryExprOrTypeTraitExprClass: 974 return VisitUnaryExprOrTypeTraitExpr(cast<UnaryExprOrTypeTraitExpr>(S), 975 asc); 976 977 case Stmt::StmtExprClass: 978 return VisitStmtExpr(cast<StmtExpr>(S), asc); 979 980 case Stmt::SwitchStmtClass: 981 return VisitSwitchStmt(cast<SwitchStmt>(S)); 982 983 case Stmt::UnaryOperatorClass: 984 return VisitUnaryOperator(cast<UnaryOperator>(S), asc); 985 986 case Stmt::WhileStmtClass: 987 return VisitWhileStmt(cast<WhileStmt>(S)); 988 } 989} 990 991CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) { 992 if (asc.alwaysAdd(*this, S)) { 993 autoCreateBlock(); 994 appendStmt(Block, S); 995 } 996 997 return VisitChildren(S); 998} 999 1000/// VisitChildren - Visit the children of a Stmt. 1001CFGBlock *CFGBuilder::VisitChildren(Stmt *Terminator) { 1002 CFGBlock *lastBlock = Block; 1003 for (Stmt::child_range I = Terminator->children(); I; ++I) 1004 if (Stmt *child = *I) 1005 if (CFGBlock *b = Visit(child)) 1006 lastBlock = b; 1007 1008 return lastBlock; 1009} 1010 1011CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A, 1012 AddStmtChoice asc) { 1013 AddressTakenLabels.insert(A->getLabel()); 1014 1015 if (asc.alwaysAdd(*this, A)) { 1016 autoCreateBlock(); 1017 appendStmt(Block, A); 1018 } 1019 1020 return Block; 1021} 1022 1023CFGBlock *CFGBuilder::VisitUnaryOperator(UnaryOperator *U, 1024 AddStmtChoice asc) { 1025 if (asc.alwaysAdd(*this, U)) { 1026 autoCreateBlock(); 1027 appendStmt(Block, U); 1028 } 1029 1030 return Visit(U->getSubExpr(), AddStmtChoice()); 1031} 1032 1033CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B, 1034 AddStmtChoice asc) { 1035 if (B->isLogicalOp()) { // && or || 1036 CFGBlock *ConfluenceBlock = Block ? Block : createBlock(); 1037 appendStmt(ConfluenceBlock, B); 1038 1039 if (badCFG) 1040 return 0; 1041 1042 // create the block evaluating the LHS 1043 CFGBlock *LHSBlock = createBlock(false); 1044 LHSBlock->setTerminator(B); 1045 1046 // create the block evaluating the RHS 1047 Succ = ConfluenceBlock; 1048 Block = NULL; 1049 CFGBlock *RHSBlock = addStmt(B->getRHS()); 1050 1051 if (RHSBlock) { 1052 if (badCFG) 1053 return 0; 1054 } else { 1055 // Create an empty block for cases where the RHS doesn't require 1056 // any explicit statements in the CFG. 1057 RHSBlock = createBlock(); 1058 } 1059 1060 // See if this is a known constant. 1061 TryResult KnownVal = tryEvaluateBool(B->getLHS()); 1062 if (KnownVal.isKnown() && (B->getOpcode() == BO_LOr)) 1063 KnownVal.negate(); 1064 1065 // Now link the LHSBlock with RHSBlock. 1066 if (B->getOpcode() == BO_LOr) { 1067 addSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 1068 addSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 1069 } else { 1070 assert(B->getOpcode() == BO_LAnd); 1071 addSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 1072 addSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 1073 } 1074 1075 // Generate the blocks for evaluating the LHS. 1076 Block = LHSBlock; 1077 return addStmt(B->getLHS()); 1078 } 1079 1080 if (B->getOpcode() == BO_Comma) { // , 1081 autoCreateBlock(); 1082 appendStmt(Block, B); 1083 addStmt(B->getRHS()); 1084 return addStmt(B->getLHS()); 1085 } 1086 1087 if (B->isAssignmentOp()) { 1088 if (asc.alwaysAdd(*this, B)) { 1089 autoCreateBlock(); 1090 appendStmt(Block, B); 1091 } 1092 Visit(B->getLHS()); 1093 return Visit(B->getRHS()); 1094 } 1095 1096 if (asc.alwaysAdd(*this, B)) { 1097 autoCreateBlock(); 1098 appendStmt(Block, B); 1099 } 1100 1101 CFGBlock *RBlock = Visit(B->getRHS()); 1102 CFGBlock *LBlock = Visit(B->getLHS()); 1103 // If visiting RHS causes us to finish 'Block', e.g. the RHS is a StmtExpr 1104 // containing a DoStmt, and the LHS doesn't create a new block, then we should 1105 // return RBlock. Otherwise we'll incorrectly return NULL. 1106 return (LBlock ? LBlock : RBlock); 1107} 1108 1109CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) { 1110 if (asc.alwaysAdd(*this, E)) { 1111 autoCreateBlock(); 1112 appendStmt(Block, E); 1113 } 1114 return Block; 1115} 1116 1117CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) { 1118 // "break" is a control-flow statement. Thus we stop processing the current 1119 // block. 1120 if (badCFG) 1121 return 0; 1122 1123 // Now create a new block that ends with the break statement. 1124 Block = createBlock(false); 1125 Block->setTerminator(B); 1126 1127 // If there is no target for the break, then we are looking at an incomplete 1128 // AST. This means that the CFG cannot be constructed. 1129 if (BreakJumpTarget.block) { 1130 addAutomaticObjDtors(ScopePos, BreakJumpTarget.scopePosition, B); 1131 addSuccessor(Block, BreakJumpTarget.block); 1132 } else 1133 badCFG = true; 1134 1135 1136 return Block; 1137} 1138 1139static bool CanThrow(Expr *E, ASTContext &Ctx) { 1140 QualType Ty = E->getType(); 1141 if (Ty->isFunctionPointerType()) 1142 Ty = Ty->getAs<PointerType>()->getPointeeType(); 1143 else if (Ty->isBlockPointerType()) 1144 Ty = Ty->getAs<BlockPointerType>()->getPointeeType(); 1145 1146 const FunctionType *FT = Ty->getAs<FunctionType>(); 1147 if (FT) { 1148 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 1149 if (Proto->isNothrow(Ctx)) 1150 return false; 1151 } 1152 return true; 1153} 1154 1155CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) { 1156 // Compute the callee type. 1157 QualType calleeType = C->getCallee()->getType(); 1158 if (calleeType == Context->BoundMemberTy) { 1159 QualType boundType = Expr::findBoundMemberType(C->getCallee()); 1160 1161 // We should only get a null bound type if processing a dependent 1162 // CFG. Recover by assuming nothing. 1163 if (!boundType.isNull()) calleeType = boundType; 1164 } 1165 1166 // If this is a call to a no-return function, this stops the block here. 1167 bool NoReturn = getFunctionExtInfo(*calleeType).getNoReturn(); 1168 1169 bool AddEHEdge = false; 1170 1171 // Languages without exceptions are assumed to not throw. 1172 if (Context->getLangOptions().Exceptions) { 1173 if (BuildOpts.AddEHEdges) 1174 AddEHEdge = true; 1175 } 1176 1177 if (FunctionDecl *FD = C->getDirectCallee()) { 1178 if (FD->hasAttr<NoReturnAttr>()) 1179 NoReturn = true; 1180 if (FD->hasAttr<NoThrowAttr>()) 1181 AddEHEdge = false; 1182 } 1183 1184 if (!CanThrow(C->getCallee(), *Context)) 1185 AddEHEdge = false; 1186 1187 if (!NoReturn && !AddEHEdge) 1188 return VisitStmt(C, asc.withAlwaysAdd(true)); 1189 1190 if (Block) { 1191 Succ = Block; 1192 if (badCFG) 1193 return 0; 1194 } 1195 1196 Block = createBlock(!NoReturn); 1197 appendStmt(Block, C); 1198 1199 if (NoReturn) { 1200 // Wire this to the exit block directly. 1201 addSuccessor(Block, &cfg->getExit()); 1202 } 1203 if (AddEHEdge) { 1204 // Add exceptional edges. 1205 if (TryTerminatedBlock) 1206 addSuccessor(Block, TryTerminatedBlock); 1207 else 1208 addSuccessor(Block, &cfg->getExit()); 1209 } 1210 1211 return VisitChildren(C); 1212} 1213 1214CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C, 1215 AddStmtChoice asc) { 1216 CFGBlock *ConfluenceBlock = Block ? Block : createBlock(); 1217 appendStmt(ConfluenceBlock, C); 1218 if (badCFG) 1219 return 0; 1220 1221 AddStmtChoice alwaysAdd = asc.withAlwaysAdd(true); 1222 Succ = ConfluenceBlock; 1223 Block = NULL; 1224 CFGBlock *LHSBlock = Visit(C->getLHS(), alwaysAdd); 1225 if (badCFG) 1226 return 0; 1227 1228 Succ = ConfluenceBlock; 1229 Block = NULL; 1230 CFGBlock *RHSBlock = Visit(C->getRHS(), alwaysAdd); 1231 if (badCFG) 1232 return 0; 1233 1234 Block = createBlock(false); 1235 // See if this is a known constant. 1236 const TryResult& KnownVal = tryEvaluateBool(C->getCond()); 1237 addSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 1238 addSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 1239 Block->setTerminator(C); 1240 return addStmt(C->getCond()); 1241} 1242 1243 1244CFGBlock *CFGBuilder::VisitCompoundStmt(CompoundStmt *C) { 1245 addLocalScopeAndDtors(C); 1246 CFGBlock *LastBlock = Block; 1247 1248 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend(); 1249 I != E; ++I ) { 1250 // If we hit a segment of code just containing ';' (NullStmts), we can 1251 // get a null block back. In such cases, just use the LastBlock 1252 if (CFGBlock *newBlock = addStmt(*I)) 1253 LastBlock = newBlock; 1254 1255 if (badCFG) 1256 return NULL; 1257 } 1258 1259 return LastBlock; 1260} 1261 1262CFGBlock *CFGBuilder::VisitConditionalOperator(AbstractConditionalOperator *C, 1263 AddStmtChoice asc) { 1264 const BinaryConditionalOperator *BCO = dyn_cast<BinaryConditionalOperator>(C); 1265 const OpaqueValueExpr *opaqueValue = (BCO ? BCO->getOpaqueValue() : NULL); 1266 1267 // Create the confluence block that will "merge" the results of the ternary 1268 // expression. 1269 CFGBlock *ConfluenceBlock = Block ? Block : createBlock(); 1270 appendStmt(ConfluenceBlock, C); 1271 if (badCFG) 1272 return 0; 1273 1274 AddStmtChoice alwaysAdd = asc.withAlwaysAdd(true); 1275 1276 // Create a block for the LHS expression if there is an LHS expression. A 1277 // GCC extension allows LHS to be NULL, causing the condition to be the 1278 // value that is returned instead. 1279 // e.g: x ?: y is shorthand for: x ? x : y; 1280 Succ = ConfluenceBlock; 1281 Block = NULL; 1282 CFGBlock *LHSBlock = 0; 1283 const Expr *trueExpr = C->getTrueExpr(); 1284 if (trueExpr != opaqueValue) { 1285 LHSBlock = Visit(C->getTrueExpr(), alwaysAdd); 1286 if (badCFG) 1287 return 0; 1288 Block = NULL; 1289 } 1290 else 1291 LHSBlock = ConfluenceBlock; 1292 1293 // Create the block for the RHS expression. 1294 Succ = ConfluenceBlock; 1295 CFGBlock *RHSBlock = Visit(C->getFalseExpr(), alwaysAdd); 1296 if (badCFG) 1297 return 0; 1298 1299 // Create the block that will contain the condition. 1300 Block = createBlock(false); 1301 1302 // See if this is a known constant. 1303 const TryResult& KnownVal = tryEvaluateBool(C->getCond()); 1304 addSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 1305 addSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 1306 Block->setTerminator(C); 1307 Expr *condExpr = C->getCond(); 1308 1309 if (opaqueValue) { 1310 // Run the condition expression if it's not trivially expressed in 1311 // terms of the opaque value (or if there is no opaque value). 1312 if (condExpr != opaqueValue) 1313 addStmt(condExpr); 1314 1315 // Before that, run the common subexpression if there was one. 1316 // At least one of this or the above will be run. 1317 return addStmt(BCO->getCommon()); 1318 } 1319 1320 return addStmt(condExpr); 1321} 1322 1323CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) { 1324 // Check if the Decl is for an __label__. If so, elide it from the 1325 // CFG entirely. 1326 if (isa<LabelDecl>(*DS->decl_begin())) 1327 return Block; 1328 1329 // This case also handles static_asserts. 1330 if (DS->isSingleDecl()) 1331 return VisitDeclSubExpr(DS); 1332 1333 CFGBlock *B = 0; 1334 1335 // FIXME: Add a reverse iterator for DeclStmt to avoid this extra copy. 1336 typedef SmallVector<Decl*,10> BufTy; 1337 BufTy Buf(DS->decl_begin(), DS->decl_end()); 1338 1339 for (BufTy::reverse_iterator I = Buf.rbegin(), E = Buf.rend(); I != E; ++I) { 1340 // Get the alignment of the new DeclStmt, padding out to >=8 bytes. 1341 unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8 1342 ? 8 : llvm::AlignOf<DeclStmt>::Alignment; 1343 1344 // Allocate the DeclStmt using the BumpPtrAllocator. It will get 1345 // automatically freed with the CFG. 1346 DeclGroupRef DG(*I); 1347 Decl *D = *I; 1348 void *Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A); 1349 DeclStmt *DSNew = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D)); 1350 1351 // Append the fake DeclStmt to block. 1352 B = VisitDeclSubExpr(DSNew); 1353 } 1354 1355 return B; 1356} 1357 1358/// VisitDeclSubExpr - Utility method to add block-level expressions for 1359/// DeclStmts and initializers in them. 1360CFGBlock *CFGBuilder::VisitDeclSubExpr(DeclStmt *DS) { 1361 assert(DS->isSingleDecl() && "Can handle single declarations only."); 1362 Decl *D = DS->getSingleDecl(); 1363 1364 if (isa<StaticAssertDecl>(D)) { 1365 // static_asserts aren't added to the CFG because they do not impact 1366 // runtime semantics. 1367 return Block; 1368 } 1369 1370 VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl()); 1371 1372 if (!VD) { 1373 autoCreateBlock(); 1374 appendStmt(Block, DS); 1375 return Block; 1376 } 1377 1378 bool IsReference = false; 1379 bool HasTemporaries = false; 1380 1381 // Destructors of temporaries in initialization expression should be called 1382 // after initialization finishes. 1383 Expr *Init = VD->getInit(); 1384 if (Init) { 1385 IsReference = VD->getType()->isReferenceType(); 1386 HasTemporaries = isa<ExprWithCleanups>(Init); 1387 1388 if (BuildOpts.AddImplicitDtors && HasTemporaries) { 1389 // Generate destructors for temporaries in initialization expression. 1390 VisitForTemporaryDtors(cast<ExprWithCleanups>(Init)->getSubExpr(), 1391 IsReference); 1392 } 1393 } 1394 1395 autoCreateBlock(); 1396 appendStmt(Block, DS); 1397 1398 if (Init) { 1399 if (HasTemporaries) 1400 // For expression with temporaries go directly to subexpression to omit 1401 // generating destructors for the second time. 1402 Visit(cast<ExprWithCleanups>(Init)->getSubExpr()); 1403 else 1404 Visit(Init); 1405 } 1406 1407 // If the type of VD is a VLA, then we must process its size expressions. 1408 for (const VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); 1409 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 1410 Block = addStmt(VA->getSizeExpr()); 1411 1412 // Remove variable from local scope. 1413 if (ScopePos && VD == *ScopePos) 1414 ++ScopePos; 1415 1416 return Block; 1417} 1418 1419CFGBlock *CFGBuilder::VisitIfStmt(IfStmt *I) { 1420 // We may see an if statement in the middle of a basic block, or it may be the 1421 // first statement we are processing. In either case, we create a new basic 1422 // block. First, we create the blocks for the then...else statements, and 1423 // then we create the block containing the if statement. If we were in the 1424 // middle of a block, we stop processing that block. That block is then the 1425 // implicit successor for the "then" and "else" clauses. 1426 1427 // Save local scope position because in case of condition variable ScopePos 1428 // won't be restored when traversing AST. 1429 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 1430 1431 // Create local scope for possible condition variable. 1432 // Store scope position. Add implicit destructor. 1433 if (VarDecl *VD = I->getConditionVariable()) { 1434 LocalScope::const_iterator BeginScopePos = ScopePos; 1435 addLocalScopeForVarDecl(VD); 1436 addAutomaticObjDtors(ScopePos, BeginScopePos, I); 1437 } 1438 1439 // The block we were processing is now finished. Make it the successor 1440 // block. 1441 if (Block) { 1442 Succ = Block; 1443 if (badCFG) 1444 return 0; 1445 } 1446 1447 // Process the false branch. 1448 CFGBlock *ElseBlock = Succ; 1449 1450 if (Stmt *Else = I->getElse()) { 1451 SaveAndRestore<CFGBlock*> sv(Succ); 1452 1453 // NULL out Block so that the recursive call to Visit will 1454 // create a new basic block. 1455 Block = NULL; 1456 1457 // If branch is not a compound statement create implicit scope 1458 // and add destructors. 1459 if (!isa<CompoundStmt>(Else)) 1460 addLocalScopeAndDtors(Else); 1461 1462 ElseBlock = addStmt(Else); 1463 1464 if (!ElseBlock) // Can occur when the Else body has all NullStmts. 1465 ElseBlock = sv.get(); 1466 else if (Block) { 1467 if (badCFG) 1468 return 0; 1469 } 1470 } 1471 1472 // Process the true branch. 1473 CFGBlock *ThenBlock; 1474 { 1475 Stmt *Then = I->getThen(); 1476 assert(Then); 1477 SaveAndRestore<CFGBlock*> sv(Succ); 1478 Block = NULL; 1479 1480 // If branch is not a compound statement create implicit scope 1481 // and add destructors. 1482 if (!isa<CompoundStmt>(Then)) 1483 addLocalScopeAndDtors(Then); 1484 1485 ThenBlock = addStmt(Then); 1486 1487 if (!ThenBlock) { 1488 // We can reach here if the "then" body has all NullStmts. 1489 // Create an empty block so we can distinguish between true and false 1490 // branches in path-sensitive analyses. 1491 ThenBlock = createBlock(false); 1492 addSuccessor(ThenBlock, sv.get()); 1493 } else if (Block) { 1494 if (badCFG) 1495 return 0; 1496 } 1497 } 1498 1499 // Now create a new block containing the if statement. 1500 Block = createBlock(false); 1501 1502 // Set the terminator of the new block to the If statement. 1503 Block->setTerminator(I); 1504 1505 // See if this is a known constant. 1506 const TryResult &KnownVal = tryEvaluateBool(I->getCond()); 1507 1508 // Now add the successors. 1509 addSuccessor(Block, KnownVal.isFalse() ? NULL : ThenBlock); 1510 addSuccessor(Block, KnownVal.isTrue()? NULL : ElseBlock); 1511 1512 // Add the condition as the last statement in the new block. This may create 1513 // new blocks as the condition may contain control-flow. Any newly created 1514 // blocks will be pointed to be "Block". 1515 Block = addStmt(I->getCond()); 1516 1517 // Finally, if the IfStmt contains a condition variable, add both the IfStmt 1518 // and the condition variable initialization to the CFG. 1519 if (VarDecl *VD = I->getConditionVariable()) { 1520 if (Expr *Init = VD->getInit()) { 1521 autoCreateBlock(); 1522 appendStmt(Block, I->getConditionVariableDeclStmt()); 1523 addStmt(Init); 1524 } 1525 } 1526 1527 return Block; 1528} 1529 1530 1531CFGBlock *CFGBuilder::VisitReturnStmt(ReturnStmt *R) { 1532 // If we were in the middle of a block we stop processing that block. 1533 // 1534 // NOTE: If a "return" appears in the middle of a block, this means that the 1535 // code afterwards is DEAD (unreachable). We still keep a basic block 1536 // for that code; a simple "mark-and-sweep" from the entry block will be 1537 // able to report such dead blocks. 1538 1539 // Create the new block. 1540 Block = createBlock(false); 1541 1542 // The Exit block is the only successor. 1543 addAutomaticObjDtors(ScopePos, LocalScope::const_iterator(), R); 1544 addSuccessor(Block, &cfg->getExit()); 1545 1546 // Add the return statement to the block. This may create new blocks if R 1547 // contains control-flow (short-circuit operations). 1548 return VisitStmt(R, AddStmtChoice::AlwaysAdd); 1549} 1550 1551CFGBlock *CFGBuilder::VisitLabelStmt(LabelStmt *L) { 1552 // Get the block of the labeled statement. Add it to our map. 1553 addStmt(L->getSubStmt()); 1554 CFGBlock *LabelBlock = Block; 1555 1556 if (!LabelBlock) // This can happen when the body is empty, i.e. 1557 LabelBlock = createBlock(); // scopes that only contains NullStmts. 1558 1559 assert(LabelMap.find(L->getDecl()) == LabelMap.end() && 1560 "label already in map"); 1561 LabelMap[L->getDecl()] = JumpTarget(LabelBlock, ScopePos); 1562 1563 // Labels partition blocks, so this is the end of the basic block we were 1564 // processing (L is the block's label). Because this is label (and we have 1565 // already processed the substatement) there is no extra control-flow to worry 1566 // about. 1567 LabelBlock->setLabel(L); 1568 if (badCFG) 1569 return 0; 1570 1571 // We set Block to NULL to allow lazy creation of a new block (if necessary); 1572 Block = NULL; 1573 1574 // This block is now the implicit successor of other blocks. 1575 Succ = LabelBlock; 1576 1577 return LabelBlock; 1578} 1579 1580CFGBlock *CFGBuilder::VisitGotoStmt(GotoStmt *G) { 1581 // Goto is a control-flow statement. Thus we stop processing the current 1582 // block and create a new one. 1583 1584 Block = createBlock(false); 1585 Block->setTerminator(G); 1586 1587 // If we already know the mapping to the label block add the successor now. 1588 LabelMapTy::iterator I = LabelMap.find(G->getLabel()); 1589 1590 if (I == LabelMap.end()) 1591 // We will need to backpatch this block later. 1592 BackpatchBlocks.push_back(JumpSource(Block, ScopePos)); 1593 else { 1594 JumpTarget JT = I->second; 1595 addAutomaticObjDtors(ScopePos, JT.scopePosition, G); 1596 addSuccessor(Block, JT.block); 1597 } 1598 1599 return Block; 1600} 1601 1602CFGBlock *CFGBuilder::VisitForStmt(ForStmt *F) { 1603 CFGBlock *LoopSuccessor = NULL; 1604 1605 // Save local scope position because in case of condition variable ScopePos 1606 // won't be restored when traversing AST. 1607 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 1608 1609 // Create local scope for init statement and possible condition variable. 1610 // Add destructor for init statement and condition variable. 1611 // Store scope position for continue statement. 1612 if (Stmt *Init = F->getInit()) 1613 addLocalScopeForStmt(Init); 1614 LocalScope::const_iterator LoopBeginScopePos = ScopePos; 1615 1616 if (VarDecl *VD = F->getConditionVariable()) 1617 addLocalScopeForVarDecl(VD); 1618 LocalScope::const_iterator ContinueScopePos = ScopePos; 1619 1620 addAutomaticObjDtors(ScopePos, save_scope_pos.get(), F); 1621 1622 // "for" is a control-flow statement. Thus we stop processing the current 1623 // block. 1624 if (Block) { 1625 if (badCFG) 1626 return 0; 1627 LoopSuccessor = Block; 1628 } else 1629 LoopSuccessor = Succ; 1630 1631 // Save the current value for the break targets. 1632 // All breaks should go to the code following the loop. 1633 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget); 1634 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 1635 1636 // Because of short-circuit evaluation, the condition of the loop can span 1637 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1638 // evaluate the condition. 1639 CFGBlock *ExitConditionBlock = createBlock(false); 1640 CFGBlock *EntryConditionBlock = ExitConditionBlock; 1641 1642 // Set the terminator for the "exit" condition block. 1643 ExitConditionBlock->setTerminator(F); 1644 1645 // Now add the actual condition to the condition block. Because the condition 1646 // itself may contain control-flow, new blocks may be created. 1647 if (Stmt *C = F->getCond()) { 1648 Block = ExitConditionBlock; 1649 EntryConditionBlock = addStmt(C); 1650 if (badCFG) 1651 return 0; 1652 assert(Block == EntryConditionBlock || 1653 (Block == 0 && EntryConditionBlock == Succ)); 1654 1655 // If this block contains a condition variable, add both the condition 1656 // variable and initializer to the CFG. 1657 if (VarDecl *VD = F->getConditionVariable()) { 1658 if (Expr *Init = VD->getInit()) { 1659 autoCreateBlock(); 1660 appendStmt(Block, F->getConditionVariableDeclStmt()); 1661 EntryConditionBlock = addStmt(Init); 1662 assert(Block == EntryConditionBlock); 1663 } 1664 } 1665 1666 if (Block) { 1667 if (badCFG) 1668 return 0; 1669 } 1670 } 1671 1672 // The condition block is the implicit successor for the loop body as well as 1673 // any code above the loop. 1674 Succ = EntryConditionBlock; 1675 1676 // See if this is a known constant. 1677 TryResult KnownVal(true); 1678 1679 if (F->getCond()) 1680 KnownVal = tryEvaluateBool(F->getCond()); 1681 1682 // Now create the loop body. 1683 { 1684 assert(F->getBody()); 1685 1686 // Save the current values for Block, Succ, and continue targets. 1687 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ); 1688 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget); 1689 1690 // Create a new block to contain the (bottom) of the loop body. 1691 Block = NULL; 1692 1693 // Loop body should end with destructor of Condition variable (if any). 1694 addAutomaticObjDtors(ScopePos, LoopBeginScopePos, F); 1695 1696 if (Stmt *I = F->getInc()) { 1697 // Generate increment code in its own basic block. This is the target of 1698 // continue statements. 1699 Succ = addStmt(I); 1700 } else { 1701 // No increment code. Create a special, empty, block that is used as the 1702 // target block for "looping back" to the start of the loop. 1703 assert(Succ == EntryConditionBlock); 1704 Succ = Block ? Block : createBlock(); 1705 } 1706 1707 // Finish up the increment (or empty) block if it hasn't been already. 1708 if (Block) { 1709 assert(Block == Succ); 1710 if (badCFG) 1711 return 0; 1712 Block = 0; 1713 } 1714 1715 ContinueJumpTarget = JumpTarget(Succ, ContinueScopePos); 1716 1717 // The starting block for the loop increment is the block that should 1718 // represent the 'loop target' for looping back to the start of the loop. 1719 ContinueJumpTarget.block->setLoopTarget(F); 1720 1721 // If body is not a compound statement create implicit scope 1722 // and add destructors. 1723 if (!isa<CompoundStmt>(F->getBody())) 1724 addLocalScopeAndDtors(F->getBody()); 1725 1726 // Now populate the body block, and in the process create new blocks as we 1727 // walk the body of the loop. 1728 CFGBlock *BodyBlock = addStmt(F->getBody()); 1729 1730 if (!BodyBlock) 1731 BodyBlock = ContinueJumpTarget.block;//can happen for "for (...;...;...);" 1732 else if (badCFG) 1733 return 0; 1734 1735 // This new body block is a successor to our "exit" condition block. 1736 addSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 1737 } 1738 1739 // Link up the condition block with the code that follows the loop. (the 1740 // false branch). 1741 addSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 1742 1743 // If the loop contains initialization, create a new block for those 1744 // statements. This block can also contain statements that precede the loop. 1745 if (Stmt *I = F->getInit()) { 1746 Block = createBlock(); 1747 return addStmt(I); 1748 } 1749 1750 // There is no loop initialization. We are thus basically a while loop. 1751 // NULL out Block to force lazy block construction. 1752 Block = NULL; 1753 Succ = EntryConditionBlock; 1754 return EntryConditionBlock; 1755} 1756 1757CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) { 1758 if (asc.alwaysAdd(*this, M)) { 1759 autoCreateBlock(); 1760 appendStmt(Block, M); 1761 } 1762 return Visit(M->getBase()); 1763} 1764 1765CFGBlock *CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) { 1766 // Objective-C fast enumeration 'for' statements: 1767 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC 1768 // 1769 // for ( Type newVariable in collection_expression ) { statements } 1770 // 1771 // becomes: 1772 // 1773 // prologue: 1774 // 1. collection_expression 1775 // T. jump to loop_entry 1776 // loop_entry: 1777 // 1. side-effects of element expression 1778 // 1. ObjCForCollectionStmt [performs binding to newVariable] 1779 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil] 1780 // TB: 1781 // statements 1782 // T. jump to loop_entry 1783 // FB: 1784 // what comes after 1785 // 1786 // and 1787 // 1788 // Type existingItem; 1789 // for ( existingItem in expression ) { statements } 1790 // 1791 // becomes: 1792 // 1793 // the same with newVariable replaced with existingItem; the binding works 1794 // the same except that for one ObjCForCollectionStmt::getElement() returns 1795 // a DeclStmt and the other returns a DeclRefExpr. 1796 // 1797 1798 CFGBlock *LoopSuccessor = 0; 1799 1800 if (Block) { 1801 if (badCFG) 1802 return 0; 1803 LoopSuccessor = Block; 1804 Block = 0; 1805 } else 1806 LoopSuccessor = Succ; 1807 1808 // Build the condition blocks. 1809 CFGBlock *ExitConditionBlock = createBlock(false); 1810 1811 // Set the terminator for the "exit" condition block. 1812 ExitConditionBlock->setTerminator(S); 1813 1814 // The last statement in the block should be the ObjCForCollectionStmt, which 1815 // performs the actual binding to 'element' and determines if there are any 1816 // more items in the collection. 1817 appendStmt(ExitConditionBlock, S); 1818 Block = ExitConditionBlock; 1819 1820 // Walk the 'element' expression to see if there are any side-effects. We 1821 // generate new blocks as necessary. We DON'T add the statement by default to 1822 // the CFG unless it contains control-flow. 1823 CFGBlock *EntryConditionBlock = Visit(S->getElement(), 1824 AddStmtChoice::NotAlwaysAdd); 1825 if (Block) { 1826 if (badCFG) 1827 return 0; 1828 Block = 0; 1829 } 1830 1831 // The condition block is the implicit successor for the loop body as well as 1832 // any code above the loop. 1833 Succ = EntryConditionBlock; 1834 1835 // Now create the true branch. 1836 { 1837 // Save the current values for Succ, continue and break targets. 1838 SaveAndRestore<CFGBlock*> save_Succ(Succ); 1839 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget), 1840 save_break(BreakJumpTarget); 1841 1842 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 1843 ContinueJumpTarget = JumpTarget(EntryConditionBlock, ScopePos); 1844 1845 CFGBlock *BodyBlock = addStmt(S->getBody()); 1846 1847 if (!BodyBlock) 1848 BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;" 1849 else if (Block) { 1850 if (badCFG) 1851 return 0; 1852 } 1853 1854 // This new body block is a successor to our "exit" condition block. 1855 addSuccessor(ExitConditionBlock, BodyBlock); 1856 } 1857 1858 // Link up the condition block with the code that follows the loop. 1859 // (the false branch). 1860 addSuccessor(ExitConditionBlock, LoopSuccessor); 1861 1862 // Now create a prologue block to contain the collection expression. 1863 Block = createBlock(); 1864 return addStmt(S->getCollection()); 1865} 1866 1867CFGBlock *CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S) { 1868 // FIXME: Add locking 'primitives' to CFG for @synchronized. 1869 1870 // Inline the body. 1871 CFGBlock *SyncBlock = addStmt(S->getSynchBody()); 1872 1873 // The sync body starts its own basic block. This makes it a little easier 1874 // for diagnostic clients. 1875 if (SyncBlock) { 1876 if (badCFG) 1877 return 0; 1878 1879 Block = 0; 1880 Succ = SyncBlock; 1881 } 1882 1883 // Add the @synchronized to the CFG. 1884 autoCreateBlock(); 1885 appendStmt(Block, S); 1886 1887 // Inline the sync expression. 1888 return addStmt(S->getSynchExpr()); 1889} 1890 1891CFGBlock *CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt *S) { 1892 // FIXME 1893 return NYS(); 1894} 1895 1896CFGBlock *CFGBuilder::VisitWhileStmt(WhileStmt *W) { 1897 CFGBlock *LoopSuccessor = NULL; 1898 1899 // Save local scope position because in case of condition variable ScopePos 1900 // won't be restored when traversing AST. 1901 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 1902 1903 // Create local scope for possible condition variable. 1904 // Store scope position for continue statement. 1905 LocalScope::const_iterator LoopBeginScopePos = ScopePos; 1906 if (VarDecl *VD = W->getConditionVariable()) { 1907 addLocalScopeForVarDecl(VD); 1908 addAutomaticObjDtors(ScopePos, LoopBeginScopePos, W); 1909 } 1910 1911 // "while" is a control-flow statement. Thus we stop processing the current 1912 // block. 1913 if (Block) { 1914 if (badCFG) 1915 return 0; 1916 LoopSuccessor = Block; 1917 Block = 0; 1918 } else 1919 LoopSuccessor = Succ; 1920 1921 // Because of short-circuit evaluation, the condition of the loop can span 1922 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 1923 // evaluate the condition. 1924 CFGBlock *ExitConditionBlock = createBlock(false); 1925 CFGBlock *EntryConditionBlock = ExitConditionBlock; 1926 1927 // Set the terminator for the "exit" condition block. 1928 ExitConditionBlock->setTerminator(W); 1929 1930 // Now add the actual condition to the condition block. Because the condition 1931 // itself may contain control-flow, new blocks may be created. Thus we update 1932 // "Succ" after adding the condition. 1933 if (Stmt *C = W->getCond()) { 1934 Block = ExitConditionBlock; 1935 EntryConditionBlock = addStmt(C); 1936 // The condition might finish the current 'Block'. 1937 Block = EntryConditionBlock; 1938 1939 // If this block contains a condition variable, add both the condition 1940 // variable and initializer to the CFG. 1941 if (VarDecl *VD = W->getConditionVariable()) { 1942 if (Expr *Init = VD->getInit()) { 1943 autoCreateBlock(); 1944 appendStmt(Block, W->getConditionVariableDeclStmt()); 1945 EntryConditionBlock = addStmt(Init); 1946 assert(Block == EntryConditionBlock); 1947 } 1948 } 1949 1950 if (Block) { 1951 if (badCFG) 1952 return 0; 1953 } 1954 } 1955 1956 // The condition block is the implicit successor for the loop body as well as 1957 // any code above the loop. 1958 Succ = EntryConditionBlock; 1959 1960 // See if this is a known constant. 1961 const TryResult& KnownVal = tryEvaluateBool(W->getCond()); 1962 1963 // Process the loop body. 1964 { 1965 assert(W->getBody()); 1966 1967 // Save the current values for Block, Succ, and continue and break targets 1968 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ); 1969 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget), 1970 save_break(BreakJumpTarget); 1971 1972 // Create an empty block to represent the transition block for looping back 1973 // to the head of the loop. 1974 Block = 0; 1975 assert(Succ == EntryConditionBlock); 1976 Succ = createBlock(); 1977 Succ->setLoopTarget(W); 1978 ContinueJumpTarget = JumpTarget(Succ, LoopBeginScopePos); 1979 1980 // All breaks should go to the code following the loop. 1981 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 1982 1983 // NULL out Block to force lazy instantiation of blocks for the body. 1984 Block = NULL; 1985 1986 // Loop body should end with destructor of Condition variable (if any). 1987 addAutomaticObjDtors(ScopePos, LoopBeginScopePos, W); 1988 1989 // If body is not a compound statement create implicit scope 1990 // and add destructors. 1991 if (!isa<CompoundStmt>(W->getBody())) 1992 addLocalScopeAndDtors(W->getBody()); 1993 1994 // Create the body. The returned block is the entry to the loop body. 1995 CFGBlock *BodyBlock = addStmt(W->getBody()); 1996 1997 if (!BodyBlock) 1998 BodyBlock = ContinueJumpTarget.block; // can happen for "while(...) ;" 1999 else if (Block) { 2000 if (badCFG) 2001 return 0; 2002 } 2003 2004 // Add the loop body entry as a successor to the condition. 2005 addSuccessor(ExitConditionBlock, KnownVal.isFalse() ? NULL : BodyBlock); 2006 } 2007 2008 // Link up the condition block with the code that follows the loop. (the 2009 // false branch). 2010 addSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 2011 2012 // There can be no more statements in the condition block since we loop back 2013 // to this block. NULL out Block to force lazy creation of another block. 2014 Block = NULL; 2015 2016 // Return the condition block, which is the dominating block for the loop. 2017 Succ = EntryConditionBlock; 2018 return EntryConditionBlock; 2019} 2020 2021 2022CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) { 2023 // FIXME: For now we pretend that @catch and the code it contains does not 2024 // exit. 2025 return Block; 2026} 2027 2028CFGBlock *CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt *S) { 2029 // FIXME: This isn't complete. We basically treat @throw like a return 2030 // statement. 2031 2032 // If we were in the middle of a block we stop processing that block. 2033 if (badCFG) 2034 return 0; 2035 2036 // Create the new block. 2037 Block = createBlock(false); 2038 2039 // The Exit block is the only successor. 2040 addSuccessor(Block, &cfg->getExit()); 2041 2042 // Add the statement to the block. This may create new blocks if S contains 2043 // control-flow (short-circuit operations). 2044 return VisitStmt(S, AddStmtChoice::AlwaysAdd); 2045} 2046 2047CFGBlock *CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr *T) { 2048 // If we were in the middle of a block we stop processing that block. 2049 if (badCFG) 2050 return 0; 2051 2052 // Create the new block. 2053 Block = createBlock(false); 2054 2055 if (TryTerminatedBlock) 2056 // The current try statement is the only successor. 2057 addSuccessor(Block, TryTerminatedBlock); 2058 else 2059 // otherwise the Exit block is the only successor. 2060 addSuccessor(Block, &cfg->getExit()); 2061 2062 // Add the statement to the block. This may create new blocks if S contains 2063 // control-flow (short-circuit operations). 2064 return VisitStmt(T, AddStmtChoice::AlwaysAdd); 2065} 2066 2067CFGBlock *CFGBuilder::VisitDoStmt(DoStmt *D) { 2068 CFGBlock *LoopSuccessor = NULL; 2069 2070 // "do...while" is a control-flow statement. Thus we stop processing the 2071 // current block. 2072 if (Block) { 2073 if (badCFG) 2074 return 0; 2075 LoopSuccessor = Block; 2076 } else 2077 LoopSuccessor = Succ; 2078 2079 // Because of short-circuit evaluation, the condition of the loop can span 2080 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that 2081 // evaluate the condition. 2082 CFGBlock *ExitConditionBlock = createBlock(false); 2083 CFGBlock *EntryConditionBlock = ExitConditionBlock; 2084 2085 // Set the terminator for the "exit" condition block. 2086 ExitConditionBlock->setTerminator(D); 2087 2088 // Now add the actual condition to the condition block. Because the condition 2089 // itself may contain control-flow, new blocks may be created. 2090 if (Stmt *C = D->getCond()) { 2091 Block = ExitConditionBlock; 2092 EntryConditionBlock = addStmt(C); 2093 if (Block) { 2094 if (badCFG) 2095 return 0; 2096 } 2097 } 2098 2099 // The condition block is the implicit successor for the loop body. 2100 Succ = EntryConditionBlock; 2101 2102 // See if this is a known constant. 2103 const TryResult &KnownVal = tryEvaluateBool(D->getCond()); 2104 2105 // Process the loop body. 2106 CFGBlock *BodyBlock = NULL; 2107 { 2108 assert(D->getBody()); 2109 2110 // Save the current values for Block, Succ, and continue and break targets 2111 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ); 2112 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget), 2113 save_break(BreakJumpTarget); 2114 2115 // All continues within this loop should go to the condition block 2116 ContinueJumpTarget = JumpTarget(EntryConditionBlock, ScopePos); 2117 2118 // All breaks should go to the code following the loop. 2119 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 2120 2121 // NULL out Block to force lazy instantiation of blocks for the body. 2122 Block = NULL; 2123 2124 // If body is not a compound statement create implicit scope 2125 // and add destructors. 2126 if (!isa<CompoundStmt>(D->getBody())) 2127 addLocalScopeAndDtors(D->getBody()); 2128 2129 // Create the body. The returned block is the entry to the loop body. 2130 BodyBlock = addStmt(D->getBody()); 2131 2132 if (!BodyBlock) 2133 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)" 2134 else if (Block) { 2135 if (badCFG) 2136 return 0; 2137 } 2138 2139 if (!KnownVal.isFalse()) { 2140 // Add an intermediate block between the BodyBlock and the 2141 // ExitConditionBlock to represent the "loop back" transition. Create an 2142 // empty block to represent the transition block for looping back to the 2143 // head of the loop. 2144 // FIXME: Can we do this more efficiently without adding another block? 2145 Block = NULL; 2146 Succ = BodyBlock; 2147 CFGBlock *LoopBackBlock = createBlock(); 2148 LoopBackBlock->setLoopTarget(D); 2149 2150 // Add the loop body entry as a successor to the condition. 2151 addSuccessor(ExitConditionBlock, LoopBackBlock); 2152 } 2153 else 2154 addSuccessor(ExitConditionBlock, NULL); 2155 } 2156 2157 // Link up the condition block with the code that follows the loop. 2158 // (the false branch). 2159 addSuccessor(ExitConditionBlock, KnownVal.isTrue() ? NULL : LoopSuccessor); 2160 2161 // There can be no more statements in the body block(s) since we loop back to 2162 // the body. NULL out Block to force lazy creation of another block. 2163 Block = NULL; 2164 2165 // Return the loop body, which is the dominating block for the loop. 2166 Succ = BodyBlock; 2167 return BodyBlock; 2168} 2169 2170CFGBlock *CFGBuilder::VisitContinueStmt(ContinueStmt *C) { 2171 // "continue" is a control-flow statement. Thus we stop processing the 2172 // current block. 2173 if (badCFG) 2174 return 0; 2175 2176 // Now create a new block that ends with the continue statement. 2177 Block = createBlock(false); 2178 Block->setTerminator(C); 2179 2180 // If there is no target for the continue, then we are looking at an 2181 // incomplete AST. This means the CFG cannot be constructed. 2182 if (ContinueJumpTarget.block) { 2183 addAutomaticObjDtors(ScopePos, ContinueJumpTarget.scopePosition, C); 2184 addSuccessor(Block, ContinueJumpTarget.block); 2185 } else 2186 badCFG = true; 2187 2188 return Block; 2189} 2190 2191CFGBlock *CFGBuilder::VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E, 2192 AddStmtChoice asc) { 2193 2194 if (asc.alwaysAdd(*this, E)) { 2195 autoCreateBlock(); 2196 appendStmt(Block, E); 2197 } 2198 2199 // VLA types have expressions that must be evaluated. 2200 CFGBlock *lastBlock = Block; 2201 2202 if (E->isArgumentType()) { 2203 for (const VariableArrayType *VA =FindVA(E->getArgumentType().getTypePtr()); 2204 VA != 0; VA = FindVA(VA->getElementType().getTypePtr())) 2205 lastBlock = addStmt(VA->getSizeExpr()); 2206 } 2207 return lastBlock; 2208} 2209 2210/// VisitStmtExpr - Utility method to handle (nested) statement 2211/// expressions (a GCC extension). 2212CFGBlock *CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) { 2213 if (asc.alwaysAdd(*this, SE)) { 2214 autoCreateBlock(); 2215 appendStmt(Block, SE); 2216 } 2217 return VisitCompoundStmt(SE->getSubStmt()); 2218} 2219 2220CFGBlock *CFGBuilder::VisitSwitchStmt(SwitchStmt *Terminator) { 2221 // "switch" is a control-flow statement. Thus we stop processing the current 2222 // block. 2223 CFGBlock *SwitchSuccessor = NULL; 2224 2225 // Save local scope position because in case of condition variable ScopePos 2226 // won't be restored when traversing AST. 2227 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 2228 2229 // Create local scope for possible condition variable. 2230 // Store scope position. Add implicit destructor. 2231 if (VarDecl *VD = Terminator->getConditionVariable()) { 2232 LocalScope::const_iterator SwitchBeginScopePos = ScopePos; 2233 addLocalScopeForVarDecl(VD); 2234 addAutomaticObjDtors(ScopePos, SwitchBeginScopePos, Terminator); 2235 } 2236 2237 if (Block) { 2238 if (badCFG) 2239 return 0; 2240 SwitchSuccessor = Block; 2241 } else SwitchSuccessor = Succ; 2242 2243 // Save the current "switch" context. 2244 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock), 2245 save_default(DefaultCaseBlock); 2246 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget); 2247 2248 // Set the "default" case to be the block after the switch statement. If the 2249 // switch statement contains a "default:", this value will be overwritten with 2250 // the block for that code. 2251 DefaultCaseBlock = SwitchSuccessor; 2252 2253 // Create a new block that will contain the switch statement. 2254 SwitchTerminatedBlock = createBlock(false); 2255 2256 // Now process the switch body. The code after the switch is the implicit 2257 // successor. 2258 Succ = SwitchSuccessor; 2259 BreakJumpTarget = JumpTarget(SwitchSuccessor, ScopePos); 2260 2261 // When visiting the body, the case statements should automatically get linked 2262 // up to the switch. We also don't keep a pointer to the body, since all 2263 // control-flow from the switch goes to case/default statements. 2264 assert(Terminator->getBody() && "switch must contain a non-NULL body"); 2265 Block = NULL; 2266 2267 // For pruning unreachable case statements, save the current state 2268 // for tracking the condition value. 2269 SaveAndRestore<bool> save_switchExclusivelyCovered(switchExclusivelyCovered, 2270 false); 2271 2272 // Determine if the switch condition can be explicitly evaluated. 2273 assert(Terminator->getCond() && "switch condition must be non-NULL"); 2274 Expr::EvalResult result; 2275 bool b = tryEvaluate(Terminator->getCond(), result); 2276 SaveAndRestore<Expr::EvalResult*> save_switchCond(switchCond, 2277 b ? &result : 0); 2278 2279 // If body is not a compound statement create implicit scope 2280 // and add destructors. 2281 if (!isa<CompoundStmt>(Terminator->getBody())) 2282 addLocalScopeAndDtors(Terminator->getBody()); 2283 2284 addStmt(Terminator->getBody()); 2285 if (Block) { 2286 if (badCFG) 2287 return 0; 2288 } 2289 2290 // If we have no "default:" case, the default transition is to the code 2291 // following the switch body. Moreover, take into account if all the 2292 // cases of a switch are covered (e.g., switching on an enum value). 2293 addSuccessor(SwitchTerminatedBlock, 2294 switchExclusivelyCovered || Terminator->isAllEnumCasesCovered() 2295 ? 0 : DefaultCaseBlock); 2296 2297 // Add the terminator and condition in the switch block. 2298 SwitchTerminatedBlock->setTerminator(Terminator); 2299 Block = SwitchTerminatedBlock; 2300 Block = addStmt(Terminator->getCond()); 2301 2302 // Finally, if the SwitchStmt contains a condition variable, add both the 2303 // SwitchStmt and the condition variable initialization to the CFG. 2304 if (VarDecl *VD = Terminator->getConditionVariable()) { 2305 if (Expr *Init = VD->getInit()) { 2306 autoCreateBlock(); 2307 appendStmt(Block, Terminator->getConditionVariableDeclStmt()); 2308 addStmt(Init); 2309 } 2310 } 2311 2312 return Block; 2313} 2314 2315static bool shouldAddCase(bool &switchExclusivelyCovered, 2316 const Expr::EvalResult *switchCond, 2317 const CaseStmt *CS, 2318 ASTContext &Ctx) { 2319 if (!switchCond) 2320 return true; 2321 2322 bool addCase = false; 2323 2324 if (!switchExclusivelyCovered) { 2325 if (switchCond->Val.isInt()) { 2326 // Evaluate the LHS of the case value. 2327 Expr::EvalResult V1; 2328 CS->getLHS()->Evaluate(V1, Ctx); 2329 assert(V1.Val.isInt()); 2330 const llvm::APSInt &condInt = switchCond->Val.getInt(); 2331 const llvm::APSInt &lhsInt = V1.Val.getInt(); 2332 2333 if (condInt == lhsInt) { 2334 addCase = true; 2335 switchExclusivelyCovered = true; 2336 } 2337 else if (condInt < lhsInt) { 2338 if (const Expr *RHS = CS->getRHS()) { 2339 // Evaluate the RHS of the case value. 2340 Expr::EvalResult V2; 2341 RHS->Evaluate(V2, Ctx); 2342 assert(V2.Val.isInt()); 2343 if (V2.Val.getInt() <= condInt) { 2344 addCase = true; 2345 switchExclusivelyCovered = true; 2346 } 2347 } 2348 } 2349 } 2350 else 2351 addCase = true; 2352 } 2353 return addCase; 2354} 2355 2356CFGBlock *CFGBuilder::VisitCaseStmt(CaseStmt *CS) { 2357 // CaseStmts are essentially labels, so they are the first statement in a 2358 // block. 2359 CFGBlock *TopBlock = 0, *LastBlock = 0; 2360 2361 if (Stmt *Sub = CS->getSubStmt()) { 2362 // For deeply nested chains of CaseStmts, instead of doing a recursion 2363 // (which can blow out the stack), manually unroll and create blocks 2364 // along the way. 2365 while (isa<CaseStmt>(Sub)) { 2366 CFGBlock *currentBlock = createBlock(false); 2367 currentBlock->setLabel(CS); 2368 2369 if (TopBlock) 2370 addSuccessor(LastBlock, currentBlock); 2371 else 2372 TopBlock = currentBlock; 2373 2374 addSuccessor(SwitchTerminatedBlock, 2375 shouldAddCase(switchExclusivelyCovered, switchCond, 2376 CS, *Context) 2377 ? currentBlock : 0); 2378 2379 LastBlock = currentBlock; 2380 CS = cast<CaseStmt>(Sub); 2381 Sub = CS->getSubStmt(); 2382 } 2383 2384 addStmt(Sub); 2385 } 2386 2387 CFGBlock *CaseBlock = Block; 2388 if (!CaseBlock) 2389 CaseBlock = createBlock(); 2390 2391 // Cases statements partition blocks, so this is the top of the basic block we 2392 // were processing (the "case XXX:" is the label). 2393 CaseBlock->setLabel(CS); 2394 2395 if (badCFG) 2396 return 0; 2397 2398 // Add this block to the list of successors for the block with the switch 2399 // statement. 2400 assert(SwitchTerminatedBlock); 2401 addSuccessor(SwitchTerminatedBlock, 2402 shouldAddCase(switchExclusivelyCovered, switchCond, 2403 CS, *Context) 2404 ? CaseBlock : 0); 2405 2406 // We set Block to NULL to allow lazy creation of a new block (if necessary) 2407 Block = NULL; 2408 2409 if (TopBlock) { 2410 addSuccessor(LastBlock, CaseBlock); 2411 Succ = TopBlock; 2412 } else { 2413 // This block is now the implicit successor of other blocks. 2414 Succ = CaseBlock; 2415 } 2416 2417 return Succ; 2418} 2419 2420CFGBlock *CFGBuilder::VisitDefaultStmt(DefaultStmt *Terminator) { 2421 if (Terminator->getSubStmt()) 2422 addStmt(Terminator->getSubStmt()); 2423 2424 DefaultCaseBlock = Block; 2425 2426 if (!DefaultCaseBlock) 2427 DefaultCaseBlock = createBlock(); 2428 2429 // Default statements partition blocks, so this is the top of the basic block 2430 // we were processing (the "default:" is the label). 2431 DefaultCaseBlock->setLabel(Terminator); 2432 2433 if (badCFG) 2434 return 0; 2435 2436 // Unlike case statements, we don't add the default block to the successors 2437 // for the switch statement immediately. This is done when we finish 2438 // processing the switch statement. This allows for the default case 2439 // (including a fall-through to the code after the switch statement) to always 2440 // be the last successor of a switch-terminated block. 2441 2442 // We set Block to NULL to allow lazy creation of a new block (if necessary) 2443 Block = NULL; 2444 2445 // This block is now the implicit successor of other blocks. 2446 Succ = DefaultCaseBlock; 2447 2448 return DefaultCaseBlock; 2449} 2450 2451CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) { 2452 // "try"/"catch" is a control-flow statement. Thus we stop processing the 2453 // current block. 2454 CFGBlock *TrySuccessor = NULL; 2455 2456 if (Block) { 2457 if (badCFG) 2458 return 0; 2459 TrySuccessor = Block; 2460 } else TrySuccessor = Succ; 2461 2462 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock; 2463 2464 // Create a new block that will contain the try statement. 2465 CFGBlock *NewTryTerminatedBlock = createBlock(false); 2466 // Add the terminator in the try block. 2467 NewTryTerminatedBlock->setTerminator(Terminator); 2468 2469 bool HasCatchAll = false; 2470 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) { 2471 // The code after the try is the implicit successor. 2472 Succ = TrySuccessor; 2473 CXXCatchStmt *CS = Terminator->getHandler(h); 2474 if (CS->getExceptionDecl() == 0) { 2475 HasCatchAll = true; 2476 } 2477 Block = NULL; 2478 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS); 2479 if (CatchBlock == 0) 2480 return 0; 2481 // Add this block to the list of successors for the block with the try 2482 // statement. 2483 addSuccessor(NewTryTerminatedBlock, CatchBlock); 2484 } 2485 if (!HasCatchAll) { 2486 if (PrevTryTerminatedBlock) 2487 addSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock); 2488 else 2489 addSuccessor(NewTryTerminatedBlock, &cfg->getExit()); 2490 } 2491 2492 // The code after the try is the implicit successor. 2493 Succ = TrySuccessor; 2494 2495 // Save the current "try" context. 2496 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock, NewTryTerminatedBlock); 2497 cfg->addTryDispatchBlock(TryTerminatedBlock); 2498 2499 assert(Terminator->getTryBlock() && "try must contain a non-NULL body"); 2500 Block = NULL; 2501 Block = addStmt(Terminator->getTryBlock()); 2502 return Block; 2503} 2504 2505CFGBlock *CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt *CS) { 2506 // CXXCatchStmt are treated like labels, so they are the first statement in a 2507 // block. 2508 2509 // Save local scope position because in case of exception variable ScopePos 2510 // won't be restored when traversing AST. 2511 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 2512 2513 // Create local scope for possible exception variable. 2514 // Store scope position. Add implicit destructor. 2515 if (VarDecl *VD = CS->getExceptionDecl()) { 2516 LocalScope::const_iterator BeginScopePos = ScopePos; 2517 addLocalScopeForVarDecl(VD); 2518 addAutomaticObjDtors(ScopePos, BeginScopePos, CS); 2519 } 2520 2521 if (CS->getHandlerBlock()) 2522 addStmt(CS->getHandlerBlock()); 2523 2524 CFGBlock *CatchBlock = Block; 2525 if (!CatchBlock) 2526 CatchBlock = createBlock(); 2527 2528 CatchBlock->setLabel(CS); 2529 2530 if (badCFG) 2531 return 0; 2532 2533 // We set Block to NULL to allow lazy creation of a new block (if necessary) 2534 Block = NULL; 2535 2536 return CatchBlock; 2537} 2538 2539CFGBlock *CFGBuilder::VisitCXXForRangeStmt(CXXForRangeStmt *S) { 2540 // C++0x for-range statements are specified as [stmt.ranged]: 2541 // 2542 // { 2543 // auto && __range = range-init; 2544 // for ( auto __begin = begin-expr, 2545 // __end = end-expr; 2546 // __begin != __end; 2547 // ++__begin ) { 2548 // for-range-declaration = *__begin; 2549 // statement 2550 // } 2551 // } 2552 2553 // Save local scope position before the addition of the implicit variables. 2554 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos); 2555 2556 // Create local scopes and destructors for range, begin and end variables. 2557 if (Stmt *Range = S->getRangeStmt()) 2558 addLocalScopeForStmt(Range); 2559 if (Stmt *BeginEnd = S->getBeginEndStmt()) 2560 addLocalScopeForStmt(BeginEnd); 2561 addAutomaticObjDtors(ScopePos, save_scope_pos.get(), S); 2562 2563 LocalScope::const_iterator ContinueScopePos = ScopePos; 2564 2565 // "for" is a control-flow statement. Thus we stop processing the current 2566 // block. 2567 CFGBlock *LoopSuccessor = NULL; 2568 if (Block) { 2569 if (badCFG) 2570 return 0; 2571 LoopSuccessor = Block; 2572 } else 2573 LoopSuccessor = Succ; 2574 2575 // Save the current value for the break targets. 2576 // All breaks should go to the code following the loop. 2577 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget); 2578 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos); 2579 2580 // The block for the __begin != __end expression. 2581 CFGBlock *ConditionBlock = createBlock(false); 2582 ConditionBlock->setTerminator(S); 2583 2584 // Now add the actual condition to the condition block. 2585 if (Expr *C = S->getCond()) { 2586 Block = ConditionBlock; 2587 CFGBlock *BeginConditionBlock = addStmt(C); 2588 if (badCFG) 2589 return 0; 2590 assert(BeginConditionBlock == ConditionBlock && 2591 "condition block in for-range was unexpectedly complex"); 2592 (void)BeginConditionBlock; 2593 } 2594 2595 // The condition block is the implicit successor for the loop body as well as 2596 // any code above the loop. 2597 Succ = ConditionBlock; 2598 2599 // See if this is a known constant. 2600 TryResult KnownVal(true); 2601 2602 if (S->getCond()) 2603 KnownVal = tryEvaluateBool(S->getCond()); 2604 2605 // Now create the loop body. 2606 { 2607 assert(S->getBody()); 2608 2609 // Save the current values for Block, Succ, and continue targets. 2610 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ); 2611 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget); 2612 2613 // Generate increment code in its own basic block. This is the target of 2614 // continue statements. 2615 Block = 0; 2616 Succ = addStmt(S->getInc()); 2617 ContinueJumpTarget = JumpTarget(Succ, ContinueScopePos); 2618 2619 // The starting block for the loop increment is the block that should 2620 // represent the 'loop target' for looping back to the start of the loop. 2621 ContinueJumpTarget.block->setLoopTarget(S); 2622 2623 // Finish up the increment block and prepare to start the loop body. 2624 assert(Block); 2625 if (badCFG) 2626 return 0; 2627 Block = 0; 2628 2629 2630 // Add implicit scope and dtors for loop variable. 2631 addLocalScopeAndDtors(S->getLoopVarStmt()); 2632 2633 // Populate a new block to contain the loop body and loop variable. 2634 Block = addStmt(S->getBody()); 2635 if (badCFG) 2636 return 0; 2637 Block = addStmt(S->getLoopVarStmt()); 2638 if (badCFG) 2639 return 0; 2640 2641 // This new body block is a successor to our condition block. 2642 addSuccessor(ConditionBlock, KnownVal.isFalse() ? 0 : Block); 2643 } 2644 2645 // Link up the condition block with the code that follows the loop (the 2646 // false branch). 2647 addSuccessor(ConditionBlock, KnownVal.isTrue() ? 0 : LoopSuccessor); 2648 2649 // Add the initialization statements. 2650 Block = createBlock(); 2651 addStmt(S->getBeginEndStmt()); 2652 return addStmt(S->getRangeStmt()); 2653} 2654 2655CFGBlock *CFGBuilder::VisitExprWithCleanups(ExprWithCleanups *E, 2656 AddStmtChoice asc) { 2657 if (BuildOpts.AddImplicitDtors) { 2658 // If adding implicit destructors visit the full expression for adding 2659 // destructors of temporaries. 2660 VisitForTemporaryDtors(E->getSubExpr()); 2661 2662 // Full expression has to be added as CFGStmt so it will be sequenced 2663 // before destructors of it's temporaries. 2664 asc = asc.withAlwaysAdd(true); 2665 } 2666 return Visit(E->getSubExpr(), asc); 2667} 2668 2669CFGBlock *CFGBuilder::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E, 2670 AddStmtChoice asc) { 2671 if (asc.alwaysAdd(*this, E)) { 2672 autoCreateBlock(); 2673 appendStmt(Block, E); 2674 2675 // We do not want to propagate the AlwaysAdd property. 2676 asc = asc.withAlwaysAdd(false); 2677 } 2678 return Visit(E->getSubExpr(), asc); 2679} 2680 2681CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C, 2682 AddStmtChoice asc) { 2683 autoCreateBlock(); 2684 if (!C->isElidable()) 2685 appendStmt(Block, C); 2686 2687 return VisitChildren(C); 2688} 2689 2690CFGBlock *CFGBuilder::VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E, 2691 AddStmtChoice asc) { 2692 if (asc.alwaysAdd(*this, E)) { 2693 autoCreateBlock(); 2694 appendStmt(Block, E); 2695 // We do not want to propagate the AlwaysAdd property. 2696 asc = asc.withAlwaysAdd(false); 2697 } 2698 return Visit(E->getSubExpr(), asc); 2699} 2700 2701CFGBlock *CFGBuilder::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C, 2702 AddStmtChoice asc) { 2703 autoCreateBlock(); 2704 appendStmt(Block, C); 2705 return VisitChildren(C); 2706} 2707 2708CFGBlock *CFGBuilder::VisitImplicitCastExpr(ImplicitCastExpr *E, 2709 AddStmtChoice asc) { 2710 if (asc.alwaysAdd(*this, E)) { 2711 autoCreateBlock(); 2712 appendStmt(Block, E); 2713 } 2714 return Visit(E->getSubExpr(), AddStmtChoice()); 2715} 2716 2717CFGBlock *CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt *I) { 2718 // Lazily create the indirect-goto dispatch block if there isn't one already. 2719 CFGBlock *IBlock = cfg->getIndirectGotoBlock(); 2720 2721 if (!IBlock) { 2722 IBlock = createBlock(false); 2723 cfg->setIndirectGotoBlock(IBlock); 2724 } 2725 2726 // IndirectGoto is a control-flow statement. Thus we stop processing the 2727 // current block and create a new one. 2728 if (badCFG) 2729 return 0; 2730 2731 Block = createBlock(false); 2732 Block->setTerminator(I); 2733 addSuccessor(Block, IBlock); 2734 return addStmt(I->getTarget()); 2735} 2736 2737CFGBlock *CFGBuilder::VisitForTemporaryDtors(Stmt *E, bool BindToTemporary) { 2738tryAgain: 2739 if (!E) { 2740 badCFG = true; 2741 return NULL; 2742 } 2743 switch (E->getStmtClass()) { 2744 default: 2745 return VisitChildrenForTemporaryDtors(E); 2746 2747 case Stmt::BinaryOperatorClass: 2748 return VisitBinaryOperatorForTemporaryDtors(cast<BinaryOperator>(E)); 2749 2750 case Stmt::CXXBindTemporaryExprClass: 2751 return VisitCXXBindTemporaryExprForTemporaryDtors( 2752 cast<CXXBindTemporaryExpr>(E), BindToTemporary); 2753 2754 case Stmt::BinaryConditionalOperatorClass: 2755 case Stmt::ConditionalOperatorClass: 2756 return VisitConditionalOperatorForTemporaryDtors( 2757 cast<AbstractConditionalOperator>(E), BindToTemporary); 2758 2759 case Stmt::ImplicitCastExprClass: 2760 // For implicit cast we want BindToTemporary to be passed further. 2761 E = cast<CastExpr>(E)->getSubExpr(); 2762 goto tryAgain; 2763 2764 case Stmt::ParenExprClass: 2765 E = cast<ParenExpr>(E)->getSubExpr(); 2766 goto tryAgain; 2767 2768 case Stmt::MaterializeTemporaryExprClass: 2769 E = cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(); 2770 goto tryAgain; 2771 } 2772} 2773 2774CFGBlock *CFGBuilder::VisitChildrenForTemporaryDtors(Stmt *E) { 2775 // When visiting children for destructors we want to visit them in reverse 2776 // order. Because there's no reverse iterator for children must to reverse 2777 // them in helper vector. 2778 typedef SmallVector<Stmt *, 4> ChildrenVect; 2779 ChildrenVect ChildrenRev; 2780 for (Stmt::child_range I = E->children(); I; ++I) { 2781 if (*I) ChildrenRev.push_back(*I); 2782 } 2783 2784 CFGBlock *B = Block; 2785 for (ChildrenVect::reverse_iterator I = ChildrenRev.rbegin(), 2786 L = ChildrenRev.rend(); I != L; ++I) { 2787 if (CFGBlock *R = VisitForTemporaryDtors(*I)) 2788 B = R; 2789 } 2790 return B; 2791} 2792 2793CFGBlock *CFGBuilder::VisitBinaryOperatorForTemporaryDtors(BinaryOperator *E) { 2794 if (E->isLogicalOp()) { 2795 // Destructors for temporaries in LHS expression should be called after 2796 // those for RHS expression. Even if this will unnecessarily create a block, 2797 // this block will be used at least by the full expression. 2798 autoCreateBlock(); 2799 CFGBlock *ConfluenceBlock = VisitForTemporaryDtors(E->getLHS()); 2800 if (badCFG) 2801 return NULL; 2802 2803 Succ = ConfluenceBlock; 2804 Block = NULL; 2805 CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS()); 2806 2807 if (RHSBlock) { 2808 if (badCFG) 2809 return NULL; 2810 2811 // If RHS expression did produce destructors we need to connect created 2812 // blocks to CFG in same manner as for binary operator itself. 2813 CFGBlock *LHSBlock = createBlock(false); 2814 LHSBlock->setTerminator(CFGTerminator(E, true)); 2815 2816 // For binary operator LHS block is before RHS in list of predecessors 2817 // of ConfluenceBlock. 2818 std::reverse(ConfluenceBlock->pred_begin(), 2819 ConfluenceBlock->pred_end()); 2820 2821 // See if this is a known constant. 2822 TryResult KnownVal = tryEvaluateBool(E->getLHS()); 2823 if (KnownVal.isKnown() && (E->getOpcode() == BO_LOr)) 2824 KnownVal.negate(); 2825 2826 // Link LHSBlock with RHSBlock exactly the same way as for binary operator 2827 // itself. 2828 if (E->getOpcode() == BO_LOr) { 2829 addSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 2830 addSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 2831 } else { 2832 assert (E->getOpcode() == BO_LAnd); 2833 addSuccessor(LHSBlock, KnownVal.isFalse() ? NULL : RHSBlock); 2834 addSuccessor(LHSBlock, KnownVal.isTrue() ? NULL : ConfluenceBlock); 2835 } 2836 2837 Block = LHSBlock; 2838 return LHSBlock; 2839 } 2840 2841 Block = ConfluenceBlock; 2842 return ConfluenceBlock; 2843 } 2844 2845 if (E->isAssignmentOp()) { 2846 // For assignment operator (=) LHS expression is visited 2847 // before RHS expression. For destructors visit them in reverse order. 2848 CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS()); 2849 CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getLHS()); 2850 return LHSBlock ? LHSBlock : RHSBlock; 2851 } 2852 2853 // For any other binary operator RHS expression is visited before 2854 // LHS expression (order of children). For destructors visit them in reverse 2855 // order. 2856 CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getLHS()); 2857 CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS()); 2858 return RHSBlock ? RHSBlock : LHSBlock; 2859} 2860 2861CFGBlock *CFGBuilder::VisitCXXBindTemporaryExprForTemporaryDtors( 2862 CXXBindTemporaryExpr *E, bool BindToTemporary) { 2863 // First add destructors for temporaries in subexpression. 2864 CFGBlock *B = VisitForTemporaryDtors(E->getSubExpr()); 2865 if (!BindToTemporary) { 2866 // If lifetime of temporary is not prolonged (by assigning to constant 2867 // reference) add destructor for it. 2868 autoCreateBlock(); 2869 appendTemporaryDtor(Block, E); 2870 B = Block; 2871 } 2872 return B; 2873} 2874 2875CFGBlock *CFGBuilder::VisitConditionalOperatorForTemporaryDtors( 2876 AbstractConditionalOperator *E, bool BindToTemporary) { 2877 // First add destructors for condition expression. Even if this will 2878 // unnecessarily create a block, this block will be used at least by the full 2879 // expression. 2880 autoCreateBlock(); 2881 CFGBlock *ConfluenceBlock = VisitForTemporaryDtors(E->getCond()); 2882 if (badCFG) 2883 return NULL; 2884 if (BinaryConditionalOperator *BCO 2885 = dyn_cast<BinaryConditionalOperator>(E)) { 2886 ConfluenceBlock = VisitForTemporaryDtors(BCO->getCommon()); 2887 if (badCFG) 2888 return NULL; 2889 } 2890 2891 // Try to add block with destructors for LHS expression. 2892 CFGBlock *LHSBlock = NULL; 2893 Succ = ConfluenceBlock; 2894 Block = NULL; 2895 LHSBlock = VisitForTemporaryDtors(E->getTrueExpr(), BindToTemporary); 2896 if (badCFG) 2897 return NULL; 2898 2899 // Try to add block with destructors for RHS expression; 2900 Succ = ConfluenceBlock; 2901 Block = NULL; 2902 CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getFalseExpr(), 2903 BindToTemporary); 2904 if (badCFG) 2905 return NULL; 2906 2907 if (!RHSBlock && !LHSBlock) { 2908 // If neither LHS nor RHS expression had temporaries to destroy don't create 2909 // more blocks. 2910 Block = ConfluenceBlock; 2911 return Block; 2912 } 2913 2914 Block = createBlock(false); 2915 Block->setTerminator(CFGTerminator(E, true)); 2916 2917 // See if this is a known constant. 2918 const TryResult &KnownVal = tryEvaluateBool(E->getCond()); 2919 2920 if (LHSBlock) { 2921 addSuccessor(Block, KnownVal.isFalse() ? NULL : LHSBlock); 2922 } else if (KnownVal.isFalse()) { 2923 addSuccessor(Block, NULL); 2924 } else { 2925 addSuccessor(Block, ConfluenceBlock); 2926 std::reverse(ConfluenceBlock->pred_begin(), ConfluenceBlock->pred_end()); 2927 } 2928 2929 if (!RHSBlock) 2930 RHSBlock = ConfluenceBlock; 2931 addSuccessor(Block, KnownVal.isTrue() ? NULL : RHSBlock); 2932 2933 return Block; 2934} 2935 2936} // end anonymous namespace 2937 2938/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has 2939/// no successors or predecessors. If this is the first block created in the 2940/// CFG, it is automatically set to be the Entry and Exit of the CFG. 2941CFGBlock *CFG::createBlock() { 2942 bool first_block = begin() == end(); 2943 2944 // Create the block. 2945 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>(); 2946 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC); 2947 Blocks.push_back(Mem, BlkBVC); 2948 2949 // If this is the first block, set it as the Entry and Exit. 2950 if (first_block) 2951 Entry = Exit = &back(); 2952 2953 // Return the block. 2954 return &back(); 2955} 2956 2957/// buildCFG - Constructs a CFG from an AST. Ownership of the returned 2958/// CFG is returned to the caller. 2959CFG* CFG::buildCFG(const Decl *D, Stmt *Statement, ASTContext *C, 2960 const BuildOptions &BO) { 2961 CFGBuilder Builder(C, BO); 2962 return Builder.buildCFG(D, Statement); 2963} 2964 2965const CXXDestructorDecl * 2966CFGImplicitDtor::getDestructorDecl(ASTContext &astContext) const { 2967 switch (getKind()) { 2968 case CFGElement::Invalid: 2969 case CFGElement::Statement: 2970 case CFGElement::Initializer: 2971 llvm_unreachable("getDestructorDecl should only be used with " 2972 "ImplicitDtors"); 2973 case CFGElement::AutomaticObjectDtor: { 2974 const VarDecl *var = cast<CFGAutomaticObjDtor>(this)->getVarDecl(); 2975 QualType ty = var->getType(); 2976 ty = ty.getNonReferenceType(); 2977 if (const ArrayType *arrayType = astContext.getAsArrayType(ty)) { 2978 ty = arrayType->getElementType(); 2979 } 2980 const RecordType *recordType = ty->getAs<RecordType>(); 2981 const CXXRecordDecl *classDecl = 2982 cast<CXXRecordDecl>(recordType->getDecl()); 2983 return classDecl->getDestructor(); 2984 } 2985 case CFGElement::TemporaryDtor: { 2986 const CXXBindTemporaryExpr *bindExpr = 2987 cast<CFGTemporaryDtor>(this)->getBindTemporaryExpr(); 2988 const CXXTemporary *temp = bindExpr->getTemporary(); 2989 return temp->getDestructor(); 2990 } 2991 case CFGElement::BaseDtor: 2992 case CFGElement::MemberDtor: 2993 2994 // Not yet supported. 2995 return 0; 2996 } 2997 llvm_unreachable("getKind() returned bogus value"); 2998 return 0; 2999} 3000 3001bool CFGImplicitDtor::isNoReturn(ASTContext &astContext) const { 3002 if (const CXXDestructorDecl *cdecl = getDestructorDecl(astContext)) { 3003 QualType ty = cdecl->getType(); 3004 return cast<FunctionType>(ty)->getNoReturnAttr(); 3005 } 3006 return false; 3007} 3008 3009//===----------------------------------------------------------------------===// 3010// CFG: Queries for BlkExprs. 3011//===----------------------------------------------------------------------===// 3012 3013namespace { 3014 typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy; 3015} 3016 3017static void FindSubExprAssignments(const Stmt *S, 3018 llvm::SmallPtrSet<const Expr*,50>& Set) { 3019 if (!S) 3020 return; 3021 3022 for (Stmt::const_child_range I = S->children(); I; ++I) { 3023 const Stmt *child = *I; 3024 if (!child) 3025 continue; 3026 3027 if (const BinaryOperator* B = dyn_cast<BinaryOperator>(child)) 3028 if (B->isAssignmentOp()) Set.insert(B); 3029 3030 FindSubExprAssignments(child, Set); 3031 } 3032} 3033 3034static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) { 3035 BlkExprMapTy* M = new BlkExprMapTy(); 3036 3037 // Look for assignments that are used as subexpressions. These are the only 3038 // assignments that we want to *possibly* register as a block-level 3039 // expression. Basically, if an assignment occurs both in a subexpression and 3040 // at the block-level, it is a block-level expression. 3041 llvm::SmallPtrSet<const Expr*,50> SubExprAssignments; 3042 3043 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) 3044 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) 3045 if (const CFGStmt *S = BI->getAs<CFGStmt>()) 3046 FindSubExprAssignments(S->getStmt(), SubExprAssignments); 3047 3048 for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I) { 3049 3050 // Iterate over the statements again on identify the Expr* and Stmt* at the 3051 // block-level that are block-level expressions. 3052 3053 for (CFGBlock::iterator BI=(*I)->begin(), EI=(*I)->end(); BI != EI; ++BI) { 3054 const CFGStmt *CS = BI->getAs<CFGStmt>(); 3055 if (!CS) 3056 continue; 3057 if (const Expr *Exp = dyn_cast<Expr>(CS->getStmt())) { 3058 assert((Exp->IgnoreParens() == Exp) && "No parens on block-level exps"); 3059 3060 if (const BinaryOperator* B = dyn_cast<BinaryOperator>(Exp)) { 3061 // Assignment expressions that are not nested within another 3062 // expression are really "statements" whose value is never used by 3063 // another expression. 3064 if (B->isAssignmentOp() && !SubExprAssignments.count(Exp)) 3065 continue; 3066 } else if (const StmtExpr *SE = dyn_cast<StmtExpr>(Exp)) { 3067 // Special handling for statement expressions. The last statement in 3068 // the statement expression is also a block-level expr. 3069 const CompoundStmt *C = SE->getSubStmt(); 3070 if (!C->body_empty()) { 3071 const Stmt *Last = C->body_back(); 3072 if (const Expr *LastEx = dyn_cast<Expr>(Last)) 3073 Last = LastEx->IgnoreParens(); 3074 unsigned x = M->size(); 3075 (*M)[Last] = x; 3076 } 3077 } 3078 3079 unsigned x = M->size(); 3080 (*M)[Exp] = x; 3081 } 3082 } 3083 3084 // Look at terminators. The condition is a block-level expression. 3085 3086 Stmt *S = (*I)->getTerminatorCondition(); 3087 3088 if (S && M->find(S) == M->end()) { 3089 unsigned x = M->size(); 3090 (*M)[S] = x; 3091 } 3092 } 3093 3094 return M; 3095} 3096 3097CFG::BlkExprNumTy CFG::getBlkExprNum(const Stmt *S) { 3098 assert(S != NULL); 3099 if (!BlkExprMap) { BlkExprMap = (void*) PopulateBlkExprMap(*this); } 3100 3101 BlkExprMapTy* M = reinterpret_cast<BlkExprMapTy*>(BlkExprMap); 3102 BlkExprMapTy::iterator I = M->find(S); 3103 return (I == M->end()) ? CFG::BlkExprNumTy() : CFG::BlkExprNumTy(I->second); 3104} 3105 3106unsigned CFG::getNumBlkExprs() { 3107 if (const BlkExprMapTy* M = reinterpret_cast<const BlkExprMapTy*>(BlkExprMap)) 3108 return M->size(); 3109 3110 // We assume callers interested in the number of BlkExprs will want 3111 // the map constructed if it doesn't already exist. 3112 BlkExprMap = (void*) PopulateBlkExprMap(*this); 3113 return reinterpret_cast<BlkExprMapTy*>(BlkExprMap)->size(); 3114} 3115 3116//===----------------------------------------------------------------------===// 3117// Filtered walking of the CFG. 3118//===----------------------------------------------------------------------===// 3119 3120bool CFGBlock::FilterEdge(const CFGBlock::FilterOptions &F, 3121 const CFGBlock *From, const CFGBlock *To) { 3122 3123 if (To && F.IgnoreDefaultsWithCoveredEnums) { 3124 // If the 'To' has no label or is labeled but the label isn't a 3125 // CaseStmt then filter this edge. 3126 if (const SwitchStmt *S = 3127 dyn_cast_or_null<SwitchStmt>(From->getTerminator().getStmt())) { 3128 if (S->isAllEnumCasesCovered()) { 3129 const Stmt *L = To->getLabel(); 3130 if (!L || !isa<CaseStmt>(L)) 3131 return true; 3132 } 3133 } 3134 } 3135 3136 return false; 3137} 3138 3139//===----------------------------------------------------------------------===// 3140// Cleanup: CFG dstor. 3141//===----------------------------------------------------------------------===// 3142 3143CFG::~CFG() { 3144 delete reinterpret_cast<const BlkExprMapTy*>(BlkExprMap); 3145} 3146 3147//===----------------------------------------------------------------------===// 3148// CFG pretty printing 3149//===----------------------------------------------------------------------===// 3150 3151namespace { 3152 3153class StmtPrinterHelper : public PrinterHelper { 3154 typedef llvm::DenseMap<const Stmt*,std::pair<unsigned,unsigned> > StmtMapTy; 3155 typedef llvm::DenseMap<const Decl*,std::pair<unsigned,unsigned> > DeclMapTy; 3156 StmtMapTy StmtMap; 3157 DeclMapTy DeclMap; 3158 signed currentBlock; 3159 unsigned currentStmt; 3160 const LangOptions &LangOpts; 3161public: 3162 3163 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO) 3164 : currentBlock(0), currentStmt(0), LangOpts(LO) 3165 { 3166 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) { 3167 unsigned j = 1; 3168 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ; 3169 BI != BEnd; ++BI, ++j ) { 3170 if (const CFGStmt *SE = BI->getAs<CFGStmt>()) { 3171 const Stmt *stmt= SE->getStmt(); 3172 std::pair<unsigned, unsigned> P((*I)->getBlockID(), j); 3173 StmtMap[stmt] = P; 3174 3175 switch (stmt->getStmtClass()) { 3176 case Stmt::DeclStmtClass: 3177 DeclMap[cast<DeclStmt>(stmt)->getSingleDecl()] = P; 3178 break; 3179 case Stmt::IfStmtClass: { 3180 const VarDecl *var = cast<IfStmt>(stmt)->getConditionVariable(); 3181 if (var) 3182 DeclMap[var] = P; 3183 break; 3184 } 3185 case Stmt::ForStmtClass: { 3186 const VarDecl *var = cast<ForStmt>(stmt)->getConditionVariable(); 3187 if (var) 3188 DeclMap[var] = P; 3189 break; 3190 } 3191 case Stmt::WhileStmtClass: { 3192 const VarDecl *var = 3193 cast<WhileStmt>(stmt)->getConditionVariable(); 3194 if (var) 3195 DeclMap[var] = P; 3196 break; 3197 } 3198 case Stmt::SwitchStmtClass: { 3199 const VarDecl *var = 3200 cast<SwitchStmt>(stmt)->getConditionVariable(); 3201 if (var) 3202 DeclMap[var] = P; 3203 break; 3204 } 3205 case Stmt::CXXCatchStmtClass: { 3206 const VarDecl *var = 3207 cast<CXXCatchStmt>(stmt)->getExceptionDecl(); 3208 if (var) 3209 DeclMap[var] = P; 3210 break; 3211 } 3212 default: 3213 break; 3214 } 3215 } 3216 } 3217 } 3218 } 3219 3220 3221 virtual ~StmtPrinterHelper() {} 3222 3223 const LangOptions &getLangOpts() const { return LangOpts; } 3224 void setBlockID(signed i) { currentBlock = i; } 3225 void setStmtID(unsigned i) { currentStmt = i; } 3226 3227 virtual bool handledStmt(Stmt *S, raw_ostream &OS) { 3228 StmtMapTy::iterator I = StmtMap.find(S); 3229 3230 if (I == StmtMap.end()) 3231 return false; 3232 3233 if (currentBlock >= 0 && I->second.first == (unsigned) currentBlock 3234 && I->second.second == currentStmt) { 3235 return false; 3236 } 3237 3238 OS << "[B" << I->second.first << "." << I->second.second << "]"; 3239 return true; 3240 } 3241 3242 bool handleDecl(const Decl *D, raw_ostream &OS) { 3243 DeclMapTy::iterator I = DeclMap.find(D); 3244 3245 if (I == DeclMap.end()) 3246 return false; 3247 3248 if (currentBlock >= 0 && I->second.first == (unsigned) currentBlock 3249 && I->second.second == currentStmt) { 3250 return false; 3251 } 3252 3253 OS << "[B" << I->second.first << "." << I->second.second << "]"; 3254 return true; 3255 } 3256}; 3257} // end anonymous namespace 3258 3259 3260namespace { 3261class CFGBlockTerminatorPrint 3262 : public StmtVisitor<CFGBlockTerminatorPrint,void> { 3263 3264 raw_ostream &OS; 3265 StmtPrinterHelper* Helper; 3266 PrintingPolicy Policy; 3267public: 3268 CFGBlockTerminatorPrint(raw_ostream &os, StmtPrinterHelper* helper, 3269 const PrintingPolicy &Policy) 3270 : OS(os), Helper(helper), Policy(Policy) {} 3271 3272 void VisitIfStmt(IfStmt *I) { 3273 OS << "if "; 3274 I->getCond()->printPretty(OS,Helper,Policy); 3275 } 3276 3277 // Default case. 3278 void VisitStmt(Stmt *Terminator) { 3279 Terminator->printPretty(OS, Helper, Policy); 3280 } 3281 3282 void VisitForStmt(ForStmt *F) { 3283 OS << "for (" ; 3284 if (F->getInit()) 3285 OS << "..."; 3286 OS << "; "; 3287 if (Stmt *C = F->getCond()) 3288 C->printPretty(OS, Helper, Policy); 3289 OS << "; "; 3290 if (F->getInc()) 3291 OS << "..."; 3292 OS << ")"; 3293 } 3294 3295 void VisitWhileStmt(WhileStmt *W) { 3296 OS << "while " ; 3297 if (Stmt *C = W->getCond()) 3298 C->printPretty(OS, Helper, Policy); 3299 } 3300 3301 void VisitDoStmt(DoStmt *D) { 3302 OS << "do ... while "; 3303 if (Stmt *C = D->getCond()) 3304 C->printPretty(OS, Helper, Policy); 3305 } 3306 3307 void VisitSwitchStmt(SwitchStmt *Terminator) { 3308 OS << "switch "; 3309 Terminator->getCond()->printPretty(OS, Helper, Policy); 3310 } 3311 3312 void VisitCXXTryStmt(CXXTryStmt *CS) { 3313 OS << "try ..."; 3314 } 3315 3316 void VisitAbstractConditionalOperator(AbstractConditionalOperator* C) { 3317 C->getCond()->printPretty(OS, Helper, Policy); 3318 OS << " ? ... : ..."; 3319 } 3320 3321 void VisitChooseExpr(ChooseExpr *C) { 3322 OS << "__builtin_choose_expr( "; 3323 C->getCond()->printPretty(OS, Helper, Policy); 3324 OS << " )"; 3325 } 3326 3327 void VisitIndirectGotoStmt(IndirectGotoStmt *I) { 3328 OS << "goto *"; 3329 I->getTarget()->printPretty(OS, Helper, Policy); 3330 } 3331 3332 void VisitBinaryOperator(BinaryOperator* B) { 3333 if (!B->isLogicalOp()) { 3334 VisitExpr(B); 3335 return; 3336 } 3337 3338 B->getLHS()->printPretty(OS, Helper, Policy); 3339 3340 switch (B->getOpcode()) { 3341 case BO_LOr: 3342 OS << " || ..."; 3343 return; 3344 case BO_LAnd: 3345 OS << " && ..."; 3346 return; 3347 default: 3348 assert(false && "Invalid logical operator."); 3349 } 3350 } 3351 3352 void VisitExpr(Expr *E) { 3353 E->printPretty(OS, Helper, Policy); 3354 } 3355}; 3356} // end anonymous namespace 3357 3358static void print_elem(raw_ostream &OS, StmtPrinterHelper* Helper, 3359 const CFGElement &E) { 3360 if (const CFGStmt *CS = E.getAs<CFGStmt>()) { 3361 const Stmt *S = CS->getStmt(); 3362 3363 if (Helper) { 3364 3365 // special printing for statement-expressions. 3366 if (const StmtExpr *SE = dyn_cast<StmtExpr>(S)) { 3367 const CompoundStmt *Sub = SE->getSubStmt(); 3368 3369 if (Sub->children()) { 3370 OS << "({ ... ; "; 3371 Helper->handledStmt(*SE->getSubStmt()->body_rbegin(),OS); 3372 OS << " })\n"; 3373 return; 3374 } 3375 } 3376 // special printing for comma expressions. 3377 if (const BinaryOperator* B = dyn_cast<BinaryOperator>(S)) { 3378 if (B->getOpcode() == BO_Comma) { 3379 OS << "... , "; 3380 Helper->handledStmt(B->getRHS(),OS); 3381 OS << '\n'; 3382 return; 3383 } 3384 } 3385 } 3386 S->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 3387 3388 if (isa<CXXOperatorCallExpr>(S)) { 3389 OS << " (OperatorCall)"; 3390 } else if (isa<CXXBindTemporaryExpr>(S)) { 3391 OS << " (BindTemporary)"; 3392 } 3393 3394 // Expressions need a newline. 3395 if (isa<Expr>(S)) 3396 OS << '\n'; 3397 3398 } else if (const CFGInitializer *IE = E.getAs<CFGInitializer>()) { 3399 const CXXCtorInitializer *I = IE->getInitializer(); 3400 if (I->isBaseInitializer()) 3401 OS << I->getBaseClass()->getAsCXXRecordDecl()->getName(); 3402 else OS << I->getAnyMember()->getName(); 3403 3404 OS << "("; 3405 if (Expr *IE = I->getInit()) 3406 IE->printPretty(OS, Helper, PrintingPolicy(Helper->getLangOpts())); 3407 OS << ")"; 3408 3409 if (I->isBaseInitializer()) 3410 OS << " (Base initializer)\n"; 3411 else OS << " (Member initializer)\n"; 3412 3413 } else if (const CFGAutomaticObjDtor *DE = E.getAs<CFGAutomaticObjDtor>()){ 3414 const VarDecl *VD = DE->getVarDecl(); 3415 Helper->handleDecl(VD, OS); 3416 3417 const Type* T = VD->getType().getTypePtr(); 3418 if (const ReferenceType* RT = T->getAs<ReferenceType>()) 3419 T = RT->getPointeeType().getTypePtr(); 3420 else if (const Type *ET = T->getArrayElementTypeNoTypeQual()) 3421 T = ET; 3422 3423 OS << ".~" << T->getAsCXXRecordDecl()->getName().str() << "()"; 3424 OS << " (Implicit destructor)\n"; 3425 3426 } else if (const CFGBaseDtor *BE = E.getAs<CFGBaseDtor>()) { 3427 const CXXBaseSpecifier *BS = BE->getBaseSpecifier(); 3428 OS << "~" << BS->getType()->getAsCXXRecordDecl()->getName() << "()"; 3429 OS << " (Base object destructor)\n"; 3430 3431 } else if (const CFGMemberDtor *ME = E.getAs<CFGMemberDtor>()) { 3432 const FieldDecl *FD = ME->getFieldDecl(); 3433 3434 const Type *T = FD->getType().getTypePtr(); 3435 if (const Type *ET = T->getArrayElementTypeNoTypeQual()) 3436 T = ET; 3437 3438 OS << "this->" << FD->getName(); 3439 OS << ".~" << T->getAsCXXRecordDecl()->getName() << "()"; 3440 OS << " (Member object destructor)\n"; 3441 3442 } else if (const CFGTemporaryDtor *TE = E.getAs<CFGTemporaryDtor>()) { 3443 const CXXBindTemporaryExpr *BT = TE->getBindTemporaryExpr(); 3444 OS << "~" << BT->getType()->getAsCXXRecordDecl()->getName() << "()"; 3445 OS << " (Temporary object destructor)\n"; 3446 } 3447} 3448 3449static void print_block(raw_ostream &OS, const CFG* cfg, 3450 const CFGBlock &B, 3451 StmtPrinterHelper* Helper, bool print_edges) { 3452 3453 if (Helper) Helper->setBlockID(B.getBlockID()); 3454 3455 // Print the header. 3456 OS << "\n [ B" << B.getBlockID(); 3457 3458 if (&B == &cfg->getEntry()) 3459 OS << " (ENTRY) ]\n"; 3460 else if (&B == &cfg->getExit()) 3461 OS << " (EXIT) ]\n"; 3462 else if (&B == cfg->getIndirectGotoBlock()) 3463 OS << " (INDIRECT GOTO DISPATCH) ]\n"; 3464 else 3465 OS << " ]\n"; 3466 3467 // Print the label of this block. 3468 if (Stmt *Label = const_cast<Stmt*>(B.getLabel())) { 3469 3470 if (print_edges) 3471 OS << " "; 3472 3473 if (LabelStmt *L = dyn_cast<LabelStmt>(Label)) 3474 OS << L->getName(); 3475 else if (CaseStmt *C = dyn_cast<CaseStmt>(Label)) { 3476 OS << "case "; 3477 C->getLHS()->printPretty(OS, Helper, 3478 PrintingPolicy(Helper->getLangOpts())); 3479 if (C->getRHS()) { 3480 OS << " ... "; 3481 C->getRHS()->printPretty(OS, Helper, 3482 PrintingPolicy(Helper->getLangOpts())); 3483 } 3484 } else if (isa<DefaultStmt>(Label)) 3485 OS << "default"; 3486 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) { 3487 OS << "catch ("; 3488 if (CS->getExceptionDecl()) 3489 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper->getLangOpts()), 3490 0); 3491 else 3492 OS << "..."; 3493 OS << ")"; 3494 3495 } else 3496 assert(false && "Invalid label statement in CFGBlock."); 3497 3498 OS << ":\n"; 3499 } 3500 3501 // Iterate through the statements in the block and print them. 3502 unsigned j = 1; 3503 3504 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ; 3505 I != E ; ++I, ++j ) { 3506 3507 // Print the statement # in the basic block and the statement itself. 3508 if (print_edges) 3509 OS << " "; 3510 3511 OS << llvm::format("%3d", j) << ": "; 3512 3513 if (Helper) 3514 Helper->setStmtID(j); 3515 3516 print_elem(OS,Helper,*I); 3517 } 3518 3519 // Print the terminator of this block. 3520 if (B.getTerminator()) { 3521 if (print_edges) 3522 OS << " "; 3523 3524 OS << " T: "; 3525 3526 if (Helper) Helper->setBlockID(-1); 3527 3528 CFGBlockTerminatorPrint TPrinter(OS, Helper, 3529 PrintingPolicy(Helper->getLangOpts())); 3530 TPrinter.Visit(const_cast<Stmt*>(B.getTerminator().getStmt())); 3531 OS << '\n'; 3532 } 3533 3534 if (print_edges) { 3535 // Print the predecessors of this block. 3536 OS << " Predecessors (" << B.pred_size() << "):"; 3537 unsigned i = 0; 3538 3539 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end(); 3540 I != E; ++I, ++i) { 3541 3542 if (i == 8 || (i-8) == 0) 3543 OS << "\n "; 3544 3545 OS << " B" << (*I)->getBlockID(); 3546 } 3547 3548 OS << '\n'; 3549 3550 // Print the successors of this block. 3551 OS << " Successors (" << B.succ_size() << "):"; 3552 i = 0; 3553 3554 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end(); 3555 I != E; ++I, ++i) { 3556 3557 if (i == 8 || (i-8) % 10 == 0) 3558 OS << "\n "; 3559 3560 if (*I) 3561 OS << " B" << (*I)->getBlockID(); 3562 else 3563 OS << " NULL"; 3564 } 3565 3566 OS << '\n'; 3567 } 3568} 3569 3570 3571/// dump - A simple pretty printer of a CFG that outputs to stderr. 3572void CFG::dump(const LangOptions &LO) const { print(llvm::errs(), LO); } 3573 3574/// print - A simple pretty printer of a CFG that outputs to an ostream. 3575void CFG::print(raw_ostream &OS, const LangOptions &LO) const { 3576 StmtPrinterHelper Helper(this, LO); 3577 3578 // Print the entry block. 3579 print_block(OS, this, getEntry(), &Helper, true); 3580 3581 // Iterate through the CFGBlocks and print them one by one. 3582 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) { 3583 // Skip the entry block, because we already printed it. 3584 if (&(**I) == &getEntry() || &(**I) == &getExit()) 3585 continue; 3586 3587 print_block(OS, this, **I, &Helper, true); 3588 } 3589 3590 // Print the exit block. 3591 print_block(OS, this, getExit(), &Helper, true); 3592 OS.flush(); 3593} 3594 3595/// dump - A simply pretty printer of a CFGBlock that outputs to stderr. 3596void CFGBlock::dump(const CFG* cfg, const LangOptions &LO) const { 3597 print(llvm::errs(), cfg, LO); 3598} 3599 3600/// print - A simple pretty printer of a CFGBlock that outputs to an ostream. 3601/// Generally this will only be called from CFG::print. 3602void CFGBlock::print(raw_ostream &OS, const CFG* cfg, 3603 const LangOptions &LO) const { 3604 StmtPrinterHelper Helper(cfg, LO); 3605 print_block(OS, cfg, *this, &Helper, true); 3606} 3607 3608/// printTerminator - A simple pretty printer of the terminator of a CFGBlock. 3609void CFGBlock::printTerminator(raw_ostream &OS, 3610 const LangOptions &LO) const { 3611 CFGBlockTerminatorPrint TPrinter(OS, NULL, PrintingPolicy(LO)); 3612 TPrinter.Visit(const_cast<Stmt*>(getTerminator().getStmt())); 3613} 3614 3615Stmt *CFGBlock::getTerminatorCondition() { 3616 Stmt *Terminator = this->Terminator; 3617 if (!Terminator) 3618 return NULL; 3619 3620 Expr *E = NULL; 3621 3622 switch (Terminator->getStmtClass()) { 3623 default: 3624 break; 3625 3626 case Stmt::ForStmtClass: 3627 E = cast<ForStmt>(Terminator)->getCond(); 3628 break; 3629 3630 case Stmt::WhileStmtClass: 3631 E = cast<WhileStmt>(Terminator)->getCond(); 3632 break; 3633 3634 case Stmt::DoStmtClass: 3635 E = cast<DoStmt>(Terminator)->getCond(); 3636 break; 3637 3638 case Stmt::IfStmtClass: 3639 E = cast<IfStmt>(Terminator)->getCond(); 3640 break; 3641 3642 case Stmt::ChooseExprClass: 3643 E = cast<ChooseExpr>(Terminator)->getCond(); 3644 break; 3645 3646 case Stmt::IndirectGotoStmtClass: 3647 E = cast<IndirectGotoStmt>(Terminator)->getTarget(); 3648 break; 3649 3650 case Stmt::SwitchStmtClass: 3651 E = cast<SwitchStmt>(Terminator)->getCond(); 3652 break; 3653 3654 case Stmt::BinaryConditionalOperatorClass: 3655 E = cast<BinaryConditionalOperator>(Terminator)->getCond(); 3656 break; 3657 3658 case Stmt::ConditionalOperatorClass: 3659 E = cast<ConditionalOperator>(Terminator)->getCond(); 3660 break; 3661 3662 case Stmt::BinaryOperatorClass: // '&&' and '||' 3663 E = cast<BinaryOperator>(Terminator)->getLHS(); 3664 break; 3665 3666 case Stmt::ObjCForCollectionStmtClass: 3667 return Terminator; 3668 } 3669 3670 return E ? E->IgnoreParens() : NULL; 3671} 3672 3673//===----------------------------------------------------------------------===// 3674// CFG Graphviz Visualization 3675//===----------------------------------------------------------------------===// 3676 3677 3678#ifndef NDEBUG 3679static StmtPrinterHelper* GraphHelper; 3680#endif 3681 3682void CFG::viewCFG(const LangOptions &LO) const { 3683#ifndef NDEBUG 3684 StmtPrinterHelper H(this, LO); 3685 GraphHelper = &H; 3686 llvm::ViewGraph(this,"CFG"); 3687 GraphHelper = NULL; 3688#endif 3689} 3690 3691namespace llvm { 3692template<> 3693struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits { 3694 3695 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} 3696 3697 static std::string getNodeLabel(const CFGBlock *Node, const CFG* Graph) { 3698 3699#ifndef NDEBUG 3700 std::string OutSStr; 3701 llvm::raw_string_ostream Out(OutSStr); 3702 print_block(Out,Graph, *Node, GraphHelper, false); 3703 std::string& OutStr = Out.str(); 3704 3705 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 3706 3707 // Process string output to make it nicer... 3708 for (unsigned i = 0; i != OutStr.length(); ++i) 3709 if (OutStr[i] == '\n') { // Left justify 3710 OutStr[i] = '\\'; 3711 OutStr.insert(OutStr.begin()+i+1, 'l'); 3712 } 3713 3714 return OutStr; 3715#else 3716 return ""; 3717#endif 3718 } 3719}; 3720} // end namespace llvm 3721