ExprEngineCallAndReturn.cpp revision 8501b7a1c4c4a9ba0ea6cb8e500e601ef3759deb
1//=-- ExprEngineCallAndReturn.cpp - Support for call/return -----*- 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 ExprEngine's support for calls and returns. 11// 12//===----------------------------------------------------------------------===// 13 14#define DEBUG_TYPE "ExprEngine" 15 16#include "clang/Analysis/Analyses/LiveVariables.h" 17#include "clang/StaticAnalyzer/Core/CheckerManager.h" 18#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 19#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 20#include "clang/AST/CXXInheritance.h" 21#include "clang/AST/DeclCXX.h" 22#include "clang/AST/ParentMap.h" 23#include "llvm/ADT/SmallSet.h" 24#include "llvm/ADT/Statistic.h" 25#include "llvm/Support/SaveAndRestore.h" 26 27using namespace clang; 28using namespace ento; 29 30STATISTIC(NumOfDynamicDispatchPathSplits, 31 "The # of times we split the path due to imprecise dynamic dispatch info"); 32 33STATISTIC(NumInlinedCalls, 34 "The # of times we inlined a call"); 35 36void ExprEngine::processCallEnter(CallEnter CE, ExplodedNode *Pred) { 37 // Get the entry block in the CFG of the callee. 38 const StackFrameContext *calleeCtx = CE.getCalleeContext(); 39 const CFG *CalleeCFG = calleeCtx->getCFG(); 40 const CFGBlock *Entry = &(CalleeCFG->getEntry()); 41 42 // Validate the CFG. 43 assert(Entry->empty()); 44 assert(Entry->succ_size() == 1); 45 46 // Get the solitary sucessor. 47 const CFGBlock *Succ = *(Entry->succ_begin()); 48 49 // Construct an edge representing the starting location in the callee. 50 BlockEdge Loc(Entry, Succ, calleeCtx); 51 52 ProgramStateRef state = Pred->getState(); 53 54 // Construct a new node and add it to the worklist. 55 bool isNew; 56 ExplodedNode *Node = G.getNode(Loc, state, false, &isNew); 57 Node->addPredecessor(Pred, G); 58 if (isNew) 59 Engine.getWorkList()->enqueue(Node); 60} 61 62// Find the last statement on the path to the exploded node and the 63// corresponding Block. 64static std::pair<const Stmt*, 65 const CFGBlock*> getLastStmt(const ExplodedNode *Node) { 66 const Stmt *S = 0; 67 const StackFrameContext *SF = 68 Node->getLocation().getLocationContext()->getCurrentStackFrame(); 69 70 // Back up through the ExplodedGraph until we reach a statement node in this 71 // stack frame. 72 while (Node) { 73 const ProgramPoint &PP = Node->getLocation(); 74 75 if (PP.getLocationContext()->getCurrentStackFrame() == SF) { 76 if (const StmtPoint *SP = dyn_cast<StmtPoint>(&PP)) { 77 S = SP->getStmt(); 78 break; 79 } else if (const CallExitEnd *CEE = dyn_cast<CallExitEnd>(&PP)) { 80 S = CEE->getCalleeContext()->getCallSite(); 81 if (S) 82 break; 83 84 // If there is no statement, this is an implicitly-generated call. 85 // We'll walk backwards over it and then continue the loop to find 86 // an actual statement. 87 const CallEnter *CE; 88 do { 89 Node = Node->getFirstPred(); 90 CE = Node->getLocationAs<CallEnter>(); 91 } while (!CE || CE->getCalleeContext() != CEE->getCalleeContext()); 92 93 // Continue searching the graph. 94 } 95 } else if (const CallEnter *CE = dyn_cast<CallEnter>(&PP)) { 96 // If we reached the CallEnter for this function, it has no statements. 97 if (CE->getCalleeContext() == SF) 98 break; 99 } 100 101 if (Node->pred_empty()) 102 return std::pair<const Stmt*, const CFGBlock*>(0, 0); 103 104 Node = *Node->pred_begin(); 105 } 106 107 const CFGBlock *Blk = 0; 108 if (S) { 109 // Now, get the enclosing basic block. 110 while (Node) { 111 const ProgramPoint &PP = Node->getLocation(); 112 if (isa<BlockEdge>(PP) && 113 (PP.getLocationContext()->getCurrentStackFrame() == SF)) { 114 BlockEdge &EPP = cast<BlockEdge>(PP); 115 Blk = EPP.getDst(); 116 break; 117 } 118 if (Node->pred_empty()) 119 return std::pair<const Stmt*, const CFGBlock*>(S, 0); 120 121 Node = *Node->pred_begin(); 122 } 123 } 124 125 return std::pair<const Stmt*, const CFGBlock*>(S, Blk); 126} 127 128/// Adjusts a return value when the called function's return type does not 129/// match the caller's expression type. This can happen when a dynamic call 130/// is devirtualized, and the overridding method has a covariant (more specific) 131/// return type than the parent's method. For C++ objects, this means we need 132/// to add base casts. 133static SVal adjustReturnValue(SVal V, QualType ExpectedTy, QualType ActualTy, 134 StoreManager &StoreMgr) { 135 // For now, the only adjustments we handle apply only to locations. 136 if (!isa<Loc>(V)) 137 return V; 138 139 // If the types already match, don't do any unnecessary work. 140 if (ExpectedTy == ActualTy) 141 return V; 142 143 // No adjustment is needed between Objective-C pointer types. 144 if (ExpectedTy->isObjCObjectPointerType() && 145 ActualTy->isObjCObjectPointerType()) 146 return V; 147 148 // C++ object pointers may need "derived-to-base" casts. 149 const CXXRecordDecl *ExpectedClass = ExpectedTy->getPointeeCXXRecordDecl(); 150 const CXXRecordDecl *ActualClass = ActualTy->getPointeeCXXRecordDecl(); 151 if (ExpectedClass && ActualClass) { 152 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 153 /*DetectVirtual=*/false); 154 if (ActualClass->isDerivedFrom(ExpectedClass, Paths) && 155 !Paths.isAmbiguous(ActualTy->getCanonicalTypeUnqualified())) { 156 return StoreMgr.evalDerivedToBase(V, Paths.front()); 157 } 158 } 159 160 // Unfortunately, Objective-C does not enforce that overridden methods have 161 // covariant return types, so we can't assert that that never happens. 162 // Be safe and return UnknownVal(). 163 return UnknownVal(); 164} 165 166void ExprEngine::removeDeadOnEndOfFunction(NodeBuilderContext& BC, 167 ExplodedNode *Pred, 168 ExplodedNodeSet &Dst) { 169 NodeBuilder Bldr(Pred, Dst, BC); 170 171 // Find the last statement in the function and the corresponding basic block. 172 const Stmt *LastSt = 0; 173 const CFGBlock *Blk = 0; 174 llvm::tie(LastSt, Blk) = getLastStmt(Pred); 175 if (!Blk || !LastSt) { 176 return; 177 } 178 179 // If the last statement is return, everything it references should stay live. 180 if (isa<ReturnStmt>(LastSt)) 181 return; 182 183 // Here, we call the Symbol Reaper with 0 stack context telling it to clean up 184 // everything on the stack. We use LastStmt as a diagnostic statement, with 185 // which the PreStmtPurgeDead point will be associated. 186 currBldrCtx = &BC; 187 removeDead(Pred, Dst, 0, 0, LastSt, 188 ProgramPoint::PostStmtPurgeDeadSymbolsKind); 189 currBldrCtx = 0; 190} 191 192/// The call exit is simulated with a sequence of nodes, which occur between 193/// CallExitBegin and CallExitEnd. The following operations occur between the 194/// two program points: 195/// 1. CallExitBegin (triggers the start of call exit sequence) 196/// 2. Bind the return value 197/// 3. Run Remove dead bindings to clean up the dead symbols from the callee. 198/// 4. CallExitEnd (switch to the caller context) 199/// 5. PostStmt<CallExpr> 200void ExprEngine::processCallExit(ExplodedNode *CEBNode) { 201 // Step 1 CEBNode was generated before the call. 202 203 const StackFrameContext *calleeCtx = 204 CEBNode->getLocationContext()->getCurrentStackFrame(); 205 206 // The parent context might not be a stack frame, so make sure we 207 // look up the first enclosing stack frame. 208 const StackFrameContext *callerCtx = 209 calleeCtx->getParent()->getCurrentStackFrame(); 210 211 const Stmt *CE = calleeCtx->getCallSite(); 212 ProgramStateRef state = CEBNode->getState(); 213 // Find the last statement in the function and the corresponding basic block. 214 const Stmt *LastSt = 0; 215 const CFGBlock *Blk = 0; 216 llvm::tie(LastSt, Blk) = getLastStmt(CEBNode); 217 218 // Generate a CallEvent /before/ cleaning the state, so that we can get the 219 // correct value for 'this' (if necessary). 220 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 221 CallEventRef<> Call = CEMgr.getCaller(calleeCtx, state); 222 223 // Step 2: generate node with bound return value: CEBNode -> BindedRetNode. 224 225 // If the callee returns an expression, bind its value to CallExpr. 226 if (CE) { 227 if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) { 228 const LocationContext *LCtx = CEBNode->getLocationContext(); 229 SVal V = state->getSVal(RS, LCtx); 230 231 const Decl *Callee = calleeCtx->getDecl(); 232 if (Callee != Call->getDecl()) { 233 QualType ReturnedTy = CallEvent::getDeclaredResultType(Callee); 234 if (!ReturnedTy.isNull()) { 235 if (const Expr *Ex = dyn_cast<Expr>(CE)) { 236 V = adjustReturnValue(V, Ex->getType(), ReturnedTy, 237 getStoreManager()); 238 } 239 } 240 } 241 242 state = state->BindExpr(CE, callerCtx, V); 243 } 244 245 // Bind the constructed object value to CXXConstructExpr. 246 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(CE)) { 247 loc::MemRegionVal This = 248 svalBuilder.getCXXThis(CCE->getConstructor()->getParent(), calleeCtx); 249 SVal ThisV = state->getSVal(This); 250 251 // If the constructed object is a prvalue, get its bindings. 252 // Note that we have to be careful here because constructors embedded 253 // in DeclStmts are not marked as lvalues. 254 if (!CCE->isGLValue()) 255 if (const MemRegion *MR = ThisV.getAsRegion()) 256 if (isa<CXXTempObjectRegion>(MR)) 257 ThisV = state->getSVal(cast<Loc>(ThisV)); 258 259 state = state->BindExpr(CCE, callerCtx, ThisV); 260 } 261 } 262 263 // Step 3: BindedRetNode -> CleanedNodes 264 // If we can find a statement and a block in the inlined function, run remove 265 // dead bindings before returning from the call. This is important to ensure 266 // that we report the issues such as leaks in the stack contexts in which 267 // they occurred. 268 ExplodedNodeSet CleanedNodes; 269 if (LastSt && Blk && AMgr.options.AnalysisPurgeOpt != PurgeNone) { 270 static SimpleProgramPointTag retValBind("ExprEngine : Bind Return Value"); 271 PostStmt Loc(LastSt, calleeCtx, &retValBind); 272 bool isNew; 273 ExplodedNode *BindedRetNode = G.getNode(Loc, state, false, &isNew); 274 BindedRetNode->addPredecessor(CEBNode, G); 275 if (!isNew) 276 return; 277 278 NodeBuilderContext Ctx(getCoreEngine(), Blk, BindedRetNode); 279 currBldrCtx = &Ctx; 280 // Here, we call the Symbol Reaper with 0 statement and caller location 281 // context, telling it to clean up everything in the callee's context 282 // (and it's children). We use LastStmt as a diagnostic statement, which 283 // which the PreStmtPurge Dead point will be associated. 284 removeDead(BindedRetNode, CleanedNodes, 0, callerCtx, LastSt, 285 ProgramPoint::PostStmtPurgeDeadSymbolsKind); 286 currBldrCtx = 0; 287 } else { 288 CleanedNodes.Add(CEBNode); 289 } 290 291 for (ExplodedNodeSet::iterator I = CleanedNodes.begin(), 292 E = CleanedNodes.end(); I != E; ++I) { 293 294 // Step 4: Generate the CallExit and leave the callee's context. 295 // CleanedNodes -> CEENode 296 CallExitEnd Loc(calleeCtx, callerCtx); 297 bool isNew; 298 ProgramStateRef CEEState = (*I == CEBNode) ? state : (*I)->getState(); 299 ExplodedNode *CEENode = G.getNode(Loc, CEEState, false, &isNew); 300 CEENode->addPredecessor(*I, G); 301 if (!isNew) 302 return; 303 304 // Step 5: Perform the post-condition check of the CallExpr and enqueue the 305 // result onto the work list. 306 // CEENode -> Dst -> WorkList 307 NodeBuilderContext Ctx(Engine, calleeCtx->getCallSiteBlock(), CEENode); 308 SaveAndRestore<const NodeBuilderContext*> NBCSave(currBldrCtx, 309 &Ctx); 310 SaveAndRestore<unsigned> CBISave(currStmtIdx, calleeCtx->getIndex()); 311 312 CallEventRef<> UpdatedCall = Call.cloneWithState(CEEState); 313 314 ExplodedNodeSet DstPostCall; 315 getCheckerManager().runCheckersForPostCall(DstPostCall, CEENode, 316 *UpdatedCall, *this, 317 /*WasInlined=*/true); 318 319 ExplodedNodeSet Dst; 320 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) { 321 getCheckerManager().runCheckersForPostObjCMessage(Dst, DstPostCall, *Msg, 322 *this, 323 /*WasInlined=*/true); 324 } else if (CE) { 325 getCheckerManager().runCheckersForPostStmt(Dst, DstPostCall, CE, 326 *this, /*WasInlined=*/true); 327 } else { 328 Dst.insert(DstPostCall); 329 } 330 331 // Enqueue the next element in the block. 332 for (ExplodedNodeSet::iterator PSI = Dst.begin(), PSE = Dst.end(); 333 PSI != PSE; ++PSI) { 334 Engine.getWorkList()->enqueue(*PSI, calleeCtx->getCallSiteBlock(), 335 calleeCtx->getIndex()+1); 336 } 337 } 338} 339 340void ExprEngine::examineStackFrames(const Decl *D, const LocationContext *LCtx, 341 bool &IsRecursive, unsigned &StackDepth) { 342 IsRecursive = false; 343 StackDepth = 0; 344 345 while (LCtx) { 346 if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LCtx)) { 347 const Decl *DI = SFC->getDecl(); 348 349 // Mark recursive (and mutually recursive) functions and always count 350 // them when measuring the stack depth. 351 if (DI == D) { 352 IsRecursive = true; 353 ++StackDepth; 354 LCtx = LCtx->getParent(); 355 continue; 356 } 357 358 // Do not count the small functions when determining the stack depth. 359 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(DI); 360 const CFG *CalleeCFG = CalleeADC->getCFG(); 361 if (CalleeCFG->getNumBlockIDs() > AMgr.options.getAlwaysInlineSize()) 362 ++StackDepth; 363 } 364 LCtx = LCtx->getParent(); 365 } 366 367} 368 369static bool IsInStdNamespace(const FunctionDecl *FD) { 370 const DeclContext *DC = FD->getEnclosingNamespaceContext(); 371 const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC); 372 if (!ND) 373 return false; 374 375 while (const DeclContext *Parent = ND->getParent()) { 376 if (!isa<NamespaceDecl>(Parent)) 377 break; 378 ND = cast<NamespaceDecl>(Parent); 379 } 380 381 return ND->getName() == "std"; 382} 383 384// Determine if we should inline the call. 385bool ExprEngine::shouldInlineDecl(const Decl *D, ExplodedNode *Pred) { 386 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); 387 const CFG *CalleeCFG = CalleeADC->getCFG(); 388 389 // It is possible that the CFG cannot be constructed. 390 // Be safe, and check if the CalleeCFG is valid. 391 if (!CalleeCFG) 392 return false; 393 394 bool IsRecursive = false; 395 unsigned StackDepth = 0; 396 examineStackFrames(D, Pred->getLocationContext(), IsRecursive, StackDepth); 397 if ((StackDepth >= AMgr.options.InlineMaxStackDepth) && 398 ((CalleeCFG->getNumBlockIDs() > AMgr.options.getAlwaysInlineSize()) 399 || IsRecursive)) 400 return false; 401 402 if (Engine.FunctionSummaries->hasReachedMaxBlockCount(D)) 403 return false; 404 405 if (CalleeCFG->getNumBlockIDs() > AMgr.options.InlineMaxFunctionSize) 406 return false; 407 408 // Do not inline variadic calls (for now). 409 if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) { 410 if (BD->isVariadic()) 411 return false; 412 } 413 else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 414 if (FD->isVariadic()) 415 return false; 416 } 417 418 if (getContext().getLangOpts().CPlusPlus) { 419 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 420 // Conditionally allow the inlining of template functions. 421 if (!getAnalysisManager().options.mayInlineTemplateFunctions()) 422 if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate) 423 return false; 424 425 // Conditionally allow the inlining of C++ standard library functions. 426 if (!getAnalysisManager().options.mayInlineCXXStandardLibrary()) 427 if (getContext().getSourceManager().isInSystemHeader(FD->getLocation())) 428 if (IsInStdNamespace(FD)) 429 return false; 430 } 431 } 432 433 // It is possible that the live variables analysis cannot be 434 // run. If so, bail out. 435 if (!CalleeADC->getAnalysis<RelaxedLiveVariables>()) 436 return false; 437 438 return true; 439} 440 441// The GDM component containing the dynamic dispatch bifurcation info. When 442// the exact type of the receiver is not known, we want to explore both paths - 443// one on which we do inline it and the other one on which we don't. This is 444// done to ensure we do not drop coverage. 445// This is the map from the receiver region to a bool, specifying either we 446// consider this region's information precise or not along the given path. 447namespace { 448 enum DynamicDispatchMode { 449 DynamicDispatchModeInlined = 1, 450 DynamicDispatchModeConservative 451 }; 452} 453REGISTER_MAP_WITH_PROGRAMSTATE(DynamicDispatchBifurcationMap, 454 const MemRegion *, unsigned) 455 456bool ExprEngine::inlineCall(const CallEvent &Call, const Decl *D, 457 NodeBuilder &Bldr, ExplodedNode *Pred, 458 ProgramStateRef State) { 459 assert(D); 460 461 const LocationContext *CurLC = Pred->getLocationContext(); 462 const StackFrameContext *CallerSFC = CurLC->getCurrentStackFrame(); 463 const LocationContext *ParentOfCallee = 0; 464 465 AnalyzerOptions &Opts = getAnalysisManager().options; 466 467 // FIXME: Refactor this check into a hypothetical CallEvent::canInline. 468 switch (Call.getKind()) { 469 case CE_Function: 470 break; 471 case CE_CXXMember: 472 case CE_CXXMemberOperator: 473 if (!Opts.mayInlineCXXMemberFunction(CIMK_MemberFunctions)) 474 return false; 475 break; 476 case CE_CXXConstructor: { 477 if (!Opts.mayInlineCXXMemberFunction(CIMK_Constructors)) 478 return false; 479 480 const CXXConstructorCall &Ctor = cast<CXXConstructorCall>(Call); 481 482 // FIXME: We don't handle constructors or destructors for arrays properly. 483 const MemRegion *Target = Ctor.getCXXThisVal().getAsRegion(); 484 if (Target && isa<ElementRegion>(Target)) 485 return false; 486 487 // FIXME: This is a hack. We don't use the correct region for a new 488 // expression, so if we inline the constructor its result will just be 489 // thrown away. This short-term hack is tracked in <rdar://problem/12180598> 490 // and the longer-term possible fix is discussed in PR12014. 491 const CXXConstructExpr *CtorExpr = Ctor.getOriginExpr(); 492 if (const Stmt *Parent = CurLC->getParentMap().getParent(CtorExpr)) 493 if (isa<CXXNewExpr>(Parent)) 494 return false; 495 496 // Inlining constructors requires including initializers in the CFG. 497 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 498 assert(ADC->getCFGBuildOptions().AddInitializers && "No CFG initializers"); 499 (void)ADC; 500 501 // If the destructor is trivial, it's always safe to inline the constructor. 502 if (Ctor.getDecl()->getParent()->hasTrivialDestructor()) 503 break; 504 505 // For other types, only inline constructors if destructor inlining is 506 // also enabled. 507 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 508 return false; 509 510 // FIXME: This is a hack. We don't handle temporary destructors 511 // right now, so we shouldn't inline their constructors. 512 if (CtorExpr->getConstructionKind() == CXXConstructExpr::CK_Complete) 513 if (!Target || !isa<DeclRegion>(Target)) 514 return false; 515 516 break; 517 } 518 case CE_CXXDestructor: { 519 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 520 return false; 521 522 // Inlining destructors requires building the CFG correctly. 523 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 524 assert(ADC->getCFGBuildOptions().AddImplicitDtors && "No CFG destructors"); 525 (void)ADC; 526 527 const CXXDestructorCall &Dtor = cast<CXXDestructorCall>(Call); 528 529 // FIXME: We don't handle constructors or destructors for arrays properly. 530 const MemRegion *Target = Dtor.getCXXThisVal().getAsRegion(); 531 if (Target && isa<ElementRegion>(Target)) 532 return false; 533 534 break; 535 } 536 case CE_CXXAllocator: 537 // Do not inline allocators until we model deallocators. 538 // This is unfortunate, but basically necessary for smart pointers and such. 539 return false; 540 case CE_Block: { 541 const BlockDataRegion *BR = cast<BlockCall>(Call).getBlockRegion(); 542 assert(BR && "If we have the block definition we should have its region"); 543 AnalysisDeclContext *BlockCtx = AMgr.getAnalysisDeclContext(D); 544 ParentOfCallee = BlockCtx->getBlockInvocationContext(CallerSFC, 545 cast<BlockDecl>(D), 546 BR); 547 break; 548 } 549 case CE_ObjCMessage: 550 if (!Opts.mayInlineObjCMethod()) 551 return false; 552 if (!(getAnalysisManager().options.IPAMode == DynamicDispatch || 553 getAnalysisManager().options.IPAMode == DynamicDispatchBifurcate)) 554 return false; 555 break; 556 } 557 558 if (!shouldInlineDecl(D, Pred)) 559 return false; 560 561 if (!ParentOfCallee) 562 ParentOfCallee = CallerSFC; 563 564 // This may be NULL, but that's fine. 565 const Expr *CallE = Call.getOriginExpr(); 566 567 // Construct a new stack frame for the callee. 568 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); 569 const StackFrameContext *CalleeSFC = 570 CalleeADC->getStackFrame(ParentOfCallee, CallE, 571 currBldrCtx->getBlock(), 572 currStmtIdx); 573 574 CallEnter Loc(CallE, CalleeSFC, CurLC); 575 576 // Construct a new state which contains the mapping from actual to 577 // formal arguments. 578 State = State->enterStackFrame(Call, CalleeSFC); 579 580 bool isNew; 581 if (ExplodedNode *N = G.getNode(Loc, State, false, &isNew)) { 582 N->addPredecessor(Pred, G); 583 if (isNew) 584 Engine.getWorkList()->enqueue(N); 585 } 586 587 // If we decided to inline the call, the successor has been manually 588 // added onto the work list so remove it from the node builder. 589 Bldr.takeNodes(Pred); 590 591 NumInlinedCalls++; 592 593 // Mark the decl as visited. 594 if (VisitedCallees) 595 VisitedCallees->insert(D); 596 597 return true; 598} 599 600static ProgramStateRef getInlineFailedState(ProgramStateRef State, 601 const Stmt *CallE) { 602 void *ReplayState = State->get<ReplayWithoutInlining>(); 603 if (!ReplayState) 604 return 0; 605 606 assert(ReplayState == (const void*)CallE && "Backtracked to the wrong call."); 607 (void)CallE; 608 609 return State->remove<ReplayWithoutInlining>(); 610} 611 612void ExprEngine::VisitCallExpr(const CallExpr *CE, ExplodedNode *Pred, 613 ExplodedNodeSet &dst) { 614 // Perform the previsit of the CallExpr. 615 ExplodedNodeSet dstPreVisit; 616 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, CE, *this); 617 618 // Get the call in its initial state. We use this as a template to perform 619 // all the checks. 620 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 621 CallEventRef<> CallTemplate 622 = CEMgr.getSimpleCall(CE, Pred->getState(), Pred->getLocationContext()); 623 624 // Evaluate the function call. We try each of the checkers 625 // to see if the can evaluate the function call. 626 ExplodedNodeSet dstCallEvaluated; 627 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 628 I != E; ++I) { 629 evalCall(dstCallEvaluated, *I, *CallTemplate); 630 } 631 632 // Finally, perform the post-condition check of the CallExpr and store 633 // the created nodes in 'Dst'. 634 // Note that if the call was inlined, dstCallEvaluated will be empty. 635 // The post-CallExpr check will occur in processCallExit. 636 getCheckerManager().runCheckersForPostStmt(dst, dstCallEvaluated, CE, 637 *this); 638} 639 640void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred, 641 const CallEvent &Call) { 642 // WARNING: At this time, the state attached to 'Call' may be older than the 643 // state in 'Pred'. This is a minor optimization since CheckerManager will 644 // use an updated CallEvent instance when calling checkers, but if 'Call' is 645 // ever used directly in this function all callers should be updated to pass 646 // the most recent state. (It is probably not worth doing the work here since 647 // for some callers this will not be necessary.) 648 649 // Run any pre-call checks using the generic call interface. 650 ExplodedNodeSet dstPreVisit; 651 getCheckerManager().runCheckersForPreCall(dstPreVisit, Pred, Call, *this); 652 653 // Actually evaluate the function call. We try each of the checkers 654 // to see if the can evaluate the function call, and get a callback at 655 // defaultEvalCall if all of them fail. 656 ExplodedNodeSet dstCallEvaluated; 657 getCheckerManager().runCheckersForEvalCall(dstCallEvaluated, dstPreVisit, 658 Call, *this); 659 660 // Finally, run any post-call checks. 661 getCheckerManager().runCheckersForPostCall(Dst, dstCallEvaluated, 662 Call, *this); 663} 664 665ProgramStateRef ExprEngine::bindReturnValue(const CallEvent &Call, 666 const LocationContext *LCtx, 667 ProgramStateRef State) { 668 const Expr *E = Call.getOriginExpr(); 669 if (!E) 670 return State; 671 672 // Some method families have known return values. 673 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) { 674 switch (Msg->getMethodFamily()) { 675 default: 676 break; 677 case OMF_autorelease: 678 case OMF_retain: 679 case OMF_self: { 680 // These methods return their receivers. 681 return State->BindExpr(E, LCtx, Msg->getReceiverSVal()); 682 } 683 } 684 } else if (const CXXConstructorCall *C = dyn_cast<CXXConstructorCall>(&Call)){ 685 return State->BindExpr(E, LCtx, C->getCXXThisVal()); 686 } 687 688 // Conjure a symbol if the return value is unknown. 689 QualType ResultTy = Call.getResultType(); 690 SValBuilder &SVB = getSValBuilder(); 691 unsigned Count = currBldrCtx->blockCount(); 692 SVal R = SVB.conjureSymbolVal(0, E, LCtx, ResultTy, Count); 693 return State->BindExpr(E, LCtx, R); 694} 695 696// Conservatively evaluate call by invalidating regions and binding 697// a conjured return value. 698void ExprEngine::conservativeEvalCall(const CallEvent &Call, NodeBuilder &Bldr, 699 ExplodedNode *Pred, ProgramStateRef State) { 700 State = Call.invalidateRegions(currBldrCtx->blockCount(), State); 701 State = bindReturnValue(Call, Pred->getLocationContext(), State); 702 703 // And make the result node. 704 Bldr.generateNode(Call.getProgramPoint(), State, Pred); 705} 706 707void ExprEngine::defaultEvalCall(NodeBuilder &Bldr, ExplodedNode *Pred, 708 const CallEvent &CallTemplate) { 709 // Make sure we have the most recent state attached to the call. 710 ProgramStateRef State = Pred->getState(); 711 CallEventRef<> Call = CallTemplate.cloneWithState(State); 712 713 if (!getAnalysisManager().shouldInlineCall()) { 714 conservativeEvalCall(*Call, Bldr, Pred, State); 715 return; 716 } 717 // Try to inline the call. 718 // The origin expression here is just used as a kind of checksum; 719 // this should still be safe even for CallEvents that don't come from exprs. 720 const Expr *E = Call->getOriginExpr(); 721 ProgramStateRef InlinedFailedState = getInlineFailedState(State, E); 722 723 if (InlinedFailedState) { 724 // If we already tried once and failed, make sure we don't retry later. 725 State = InlinedFailedState; 726 } else { 727 RuntimeDefinition RD = Call->getRuntimeDefinition(); 728 const Decl *D = RD.getDecl(); 729 if (D) { 730 if (RD.mayHaveOtherDefinitions()) { 731 // Explore with and without inlining the call. 732 if (getAnalysisManager().options.IPAMode == DynamicDispatchBifurcate) { 733 BifurcateCall(RD.getDispatchRegion(), *Call, D, Bldr, Pred); 734 return; 735 } 736 737 // Don't inline if we're not in any dynamic dispatch mode. 738 if (getAnalysisManager().options.IPAMode != DynamicDispatch) { 739 conservativeEvalCall(*Call, Bldr, Pred, State); 740 return; 741 } 742 } 743 744 // We are not bifurcating and we do have a Decl, so just inline. 745 if (inlineCall(*Call, D, Bldr, Pred, State)) 746 return; 747 } 748 } 749 750 // If we can't inline it, handle the return value and invalidate the regions. 751 conservativeEvalCall(*Call, Bldr, Pred, State); 752} 753 754void ExprEngine::BifurcateCall(const MemRegion *BifurReg, 755 const CallEvent &Call, const Decl *D, 756 NodeBuilder &Bldr, ExplodedNode *Pred) { 757 assert(BifurReg); 758 BifurReg = BifurReg->StripCasts(); 759 760 // Check if we've performed the split already - note, we only want 761 // to split the path once per memory region. 762 ProgramStateRef State = Pred->getState(); 763 const unsigned *BState = 764 State->get<DynamicDispatchBifurcationMap>(BifurReg); 765 if (BState) { 766 // If we are on "inline path", keep inlining if possible. 767 if (*BState == DynamicDispatchModeInlined) 768 if (inlineCall(Call, D, Bldr, Pred, State)) 769 return; 770 // If inline failed, or we are on the path where we assume we 771 // don't have enough info about the receiver to inline, conjure the 772 // return value and invalidate the regions. 773 conservativeEvalCall(Call, Bldr, Pred, State); 774 return; 775 } 776 777 // If we got here, this is the first time we process a message to this 778 // region, so split the path. 779 ProgramStateRef IState = 780 State->set<DynamicDispatchBifurcationMap>(BifurReg, 781 DynamicDispatchModeInlined); 782 inlineCall(Call, D, Bldr, Pred, IState); 783 784 ProgramStateRef NoIState = 785 State->set<DynamicDispatchBifurcationMap>(BifurReg, 786 DynamicDispatchModeConservative); 787 conservativeEvalCall(Call, Bldr, Pred, NoIState); 788 789 NumOfDynamicDispatchPathSplits++; 790 return; 791} 792 793 794void ExprEngine::VisitReturnStmt(const ReturnStmt *RS, ExplodedNode *Pred, 795 ExplodedNodeSet &Dst) { 796 797 ExplodedNodeSet dstPreVisit; 798 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, RS, *this); 799 800 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 801 802 if (RS->getRetValue()) { 803 for (ExplodedNodeSet::iterator it = dstPreVisit.begin(), 804 ei = dstPreVisit.end(); it != ei; ++it) { 805 B.generateNode(RS, *it, (*it)->getState()); 806 } 807 } 808} 809