ExprEngineCallAndReturn.cpp revision 55fc873017f10f6f566b182b70f6fc22aefa3464
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/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 17#include "clang/AST/CXXInheritance.h" 18#include "clang/AST/DeclCXX.h" 19#include "clang/AST/ParentMap.h" 20#include "clang/Analysis/Analyses/LiveVariables.h" 21#include "clang/StaticAnalyzer/Core/CheckerManager.h" 22#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.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*>((Stmt*)0, (CFGBlock*)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, (CFGBlock*)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 ExpectedTy = ExpectedTy.getCanonicalType(); 141 ActualTy = ActualTy.getCanonicalType(); 142 if (ExpectedTy == ActualTy) 143 return V; 144 145 // No adjustment is needed between Objective-C pointer types. 146 if (ExpectedTy->isObjCObjectPointerType() && 147 ActualTy->isObjCObjectPointerType()) 148 return V; 149 150 // C++ object pointers may need "derived-to-base" casts. 151 const CXXRecordDecl *ExpectedClass = ExpectedTy->getPointeeCXXRecordDecl(); 152 const CXXRecordDecl *ActualClass = ActualTy->getPointeeCXXRecordDecl(); 153 if (ExpectedClass && ActualClass) { 154 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 155 /*DetectVirtual=*/false); 156 if (ActualClass->isDerivedFrom(ExpectedClass, Paths) && 157 !Paths.isAmbiguous(ActualTy->getCanonicalTypeUnqualified())) { 158 return StoreMgr.evalDerivedToBase(V, Paths.front()); 159 } 160 } 161 162 // Unfortunately, Objective-C does not enforce that overridden methods have 163 // covariant return types, so we can't assert that that never happens. 164 // Be safe and return UnknownVal(). 165 return UnknownVal(); 166} 167 168void ExprEngine::removeDeadOnEndOfFunction(NodeBuilderContext& BC, 169 ExplodedNode *Pred, 170 ExplodedNodeSet &Dst) { 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 Dst.Add(Pred); 177 return; 178 } 179 180 // Here, we destroy the current location context. We use the current 181 // function's entire body as a diagnostic statement, with which the program 182 // point will be associated. However, we only want to use LastStmt as a 183 // reference for what to clean up if it's a ReturnStmt; otherwise, everything 184 // is dead. 185 SaveAndRestore<const NodeBuilderContext *> NodeContextRAII(currBldrCtx, &BC); 186 const LocationContext *LCtx = Pred->getLocationContext(); 187 removeDead(Pred, Dst, dyn_cast<ReturnStmt>(LastSt), LCtx, 188 LCtx->getAnalysisDeclContext()->getBody(), 189 ProgramPoint::PostStmtPurgeDeadSymbolsKind); 190} 191 192static bool wasDifferentDeclUsedForInlining(CallEventRef<> Call, 193 const StackFrameContext *calleeCtx) { 194 const Decl *RuntimeCallee = calleeCtx->getDecl(); 195 const Decl *StaticDecl = Call->getDecl(); 196 assert(RuntimeCallee); 197 if (!StaticDecl) 198 return true; 199 return RuntimeCallee->getCanonicalDecl() != StaticDecl->getCanonicalDecl(); 200} 201 202/// The call exit is simulated with a sequence of nodes, which occur between 203/// CallExitBegin and CallExitEnd. The following operations occur between the 204/// two program points: 205/// 1. CallExitBegin (triggers the start of call exit sequence) 206/// 2. Bind the return value 207/// 3. Run Remove dead bindings to clean up the dead symbols from the callee. 208/// 4. CallExitEnd (switch to the caller context) 209/// 5. PostStmt<CallExpr> 210void ExprEngine::processCallExit(ExplodedNode *CEBNode) { 211 // Step 1 CEBNode was generated before the call. 212 213 const StackFrameContext *calleeCtx = 214 CEBNode->getLocationContext()->getCurrentStackFrame(); 215 216 // The parent context might not be a stack frame, so make sure we 217 // look up the first enclosing stack frame. 218 const StackFrameContext *callerCtx = 219 calleeCtx->getParent()->getCurrentStackFrame(); 220 221 const Stmt *CE = calleeCtx->getCallSite(); 222 ProgramStateRef state = CEBNode->getState(); 223 // Find the last statement in the function and the corresponding basic block. 224 const Stmt *LastSt = 0; 225 const CFGBlock *Blk = 0; 226 llvm::tie(LastSt, Blk) = getLastStmt(CEBNode); 227 228 // Generate a CallEvent /before/ cleaning the state, so that we can get the 229 // correct value for 'this' (if necessary). 230 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 231 CallEventRef<> Call = CEMgr.getCaller(calleeCtx, state); 232 233 // Step 2: generate node with bound return value: CEBNode -> BindedRetNode. 234 235 // If the callee returns an expression, bind its value to CallExpr. 236 if (CE) { 237 if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) { 238 const LocationContext *LCtx = CEBNode->getLocationContext(); 239 SVal V = state->getSVal(RS, LCtx); 240 241 // Ensure that the return type matches the type of the returned Expr. 242 if (wasDifferentDeclUsedForInlining(Call, calleeCtx)) { 243 QualType ReturnedTy = 244 CallEvent::getDeclaredResultType(calleeCtx->getDecl()); 245 if (!ReturnedTy.isNull()) { 246 if (const Expr *Ex = dyn_cast<Expr>(CE)) { 247 V = adjustReturnValue(V, Ex->getType(), ReturnedTy, 248 getStoreManager()); 249 } 250 } 251 } 252 253 state = state->BindExpr(CE, callerCtx, V); 254 } 255 256 // Bind the constructed object value to CXXConstructExpr. 257 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(CE)) { 258 loc::MemRegionVal This = 259 svalBuilder.getCXXThis(CCE->getConstructor()->getParent(), calleeCtx); 260 SVal ThisV = state->getSVal(This); 261 262 // If the constructed object is a prvalue, get its bindings. 263 // Note that we have to be careful here because constructors embedded 264 // in DeclStmts are not marked as lvalues. 265 if (!CCE->isGLValue()) 266 if (const MemRegion *MR = ThisV.getAsRegion()) 267 if (isa<CXXTempObjectRegion>(MR)) 268 ThisV = state->getSVal(cast<Loc>(ThisV)); 269 270 state = state->BindExpr(CCE, callerCtx, ThisV); 271 } 272 } 273 274 // Step 3: BindedRetNode -> CleanedNodes 275 // If we can find a statement and a block in the inlined function, run remove 276 // dead bindings before returning from the call. This is important to ensure 277 // that we report the issues such as leaks in the stack contexts in which 278 // they occurred. 279 ExplodedNodeSet CleanedNodes; 280 if (LastSt && Blk && AMgr.options.AnalysisPurgeOpt != PurgeNone) { 281 static SimpleProgramPointTag retValBind("ExprEngine : Bind Return Value"); 282 PostStmt Loc(LastSt, calleeCtx, &retValBind); 283 bool isNew; 284 ExplodedNode *BindedRetNode = G.getNode(Loc, state, false, &isNew); 285 BindedRetNode->addPredecessor(CEBNode, G); 286 if (!isNew) 287 return; 288 289 NodeBuilderContext Ctx(getCoreEngine(), Blk, BindedRetNode); 290 currBldrCtx = &Ctx; 291 // Here, we call the Symbol Reaper with 0 statement and callee location 292 // context, telling it to clean up everything in the callee's context 293 // (and its children). We use the callee's function body as a diagnostic 294 // statement, with which the program point will be associated. 295 removeDead(BindedRetNode, CleanedNodes, 0, calleeCtx, 296 calleeCtx->getAnalysisDeclContext()->getBody(), 297 ProgramPoint::PostStmtPurgeDeadSymbolsKind); 298 currBldrCtx = 0; 299 } else { 300 CleanedNodes.Add(CEBNode); 301 } 302 303 for (ExplodedNodeSet::iterator I = CleanedNodes.begin(), 304 E = CleanedNodes.end(); I != E; ++I) { 305 306 // Step 4: Generate the CallExit and leave the callee's context. 307 // CleanedNodes -> CEENode 308 CallExitEnd Loc(calleeCtx, callerCtx); 309 bool isNew; 310 ProgramStateRef CEEState = (*I == CEBNode) ? state : (*I)->getState(); 311 ExplodedNode *CEENode = G.getNode(Loc, CEEState, false, &isNew); 312 CEENode->addPredecessor(*I, G); 313 if (!isNew) 314 return; 315 316 // Step 5: Perform the post-condition check of the CallExpr and enqueue the 317 // result onto the work list. 318 // CEENode -> Dst -> WorkList 319 NodeBuilderContext Ctx(Engine, calleeCtx->getCallSiteBlock(), CEENode); 320 SaveAndRestore<const NodeBuilderContext*> NBCSave(currBldrCtx, 321 &Ctx); 322 SaveAndRestore<unsigned> CBISave(currStmtIdx, calleeCtx->getIndex()); 323 324 CallEventRef<> UpdatedCall = Call.cloneWithState(CEEState); 325 326 ExplodedNodeSet DstPostCall; 327 getCheckerManager().runCheckersForPostCall(DstPostCall, CEENode, 328 *UpdatedCall, *this, 329 /*WasInlined=*/true); 330 331 ExplodedNodeSet Dst; 332 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) { 333 getCheckerManager().runCheckersForPostObjCMessage(Dst, DstPostCall, *Msg, 334 *this, 335 /*WasInlined=*/true); 336 } else if (CE) { 337 getCheckerManager().runCheckersForPostStmt(Dst, DstPostCall, CE, 338 *this, /*WasInlined=*/true); 339 } else { 340 Dst.insert(DstPostCall); 341 } 342 343 // Enqueue the next element in the block. 344 for (ExplodedNodeSet::iterator PSI = Dst.begin(), PSE = Dst.end(); 345 PSI != PSE; ++PSI) { 346 Engine.getWorkList()->enqueue(*PSI, calleeCtx->getCallSiteBlock(), 347 calleeCtx->getIndex()+1); 348 } 349 } 350} 351 352void ExprEngine::examineStackFrames(const Decl *D, const LocationContext *LCtx, 353 bool &IsRecursive, unsigned &StackDepth) { 354 IsRecursive = false; 355 StackDepth = 0; 356 357 while (LCtx) { 358 if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LCtx)) { 359 const Decl *DI = SFC->getDecl(); 360 361 // Mark recursive (and mutually recursive) functions and always count 362 // them when measuring the stack depth. 363 if (DI == D) { 364 IsRecursive = true; 365 ++StackDepth; 366 LCtx = LCtx->getParent(); 367 continue; 368 } 369 370 // Do not count the small functions when determining the stack depth. 371 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(DI); 372 const CFG *CalleeCFG = CalleeADC->getCFG(); 373 if (CalleeCFG->getNumBlockIDs() > AMgr.options.getAlwaysInlineSize()) 374 ++StackDepth; 375 } 376 LCtx = LCtx->getParent(); 377 } 378 379} 380 381static bool IsInStdNamespace(const FunctionDecl *FD) { 382 const DeclContext *DC = FD->getEnclosingNamespaceContext(); 383 const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC); 384 if (!ND) 385 return false; 386 387 while (const DeclContext *Parent = ND->getParent()) { 388 if (!isa<NamespaceDecl>(Parent)) 389 break; 390 ND = cast<NamespaceDecl>(Parent); 391 } 392 393 return ND->getName() == "std"; 394} 395 396// Determine if we should inline the call. 397bool ExprEngine::shouldInlineDecl(const Decl *D, ExplodedNode *Pred) { 398 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); 399 const CFG *CalleeCFG = CalleeADC->getCFG(); 400 401 // It is possible that the CFG cannot be constructed. 402 // Be safe, and check if the CalleeCFG is valid. 403 if (!CalleeCFG) 404 return false; 405 406 bool IsRecursive = false; 407 unsigned StackDepth = 0; 408 examineStackFrames(D, Pred->getLocationContext(), IsRecursive, StackDepth); 409 if ((StackDepth >= AMgr.options.InlineMaxStackDepth) && 410 ((CalleeCFG->getNumBlockIDs() > AMgr.options.getAlwaysInlineSize()) 411 || IsRecursive)) 412 return false; 413 414 if (Engine.FunctionSummaries->hasReachedMaxBlockCount(D)) 415 return false; 416 417 if (CalleeCFG->getNumBlockIDs() > AMgr.options.InlineMaxFunctionSize) 418 return false; 419 420 // Do not inline variadic calls (for now). 421 if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) { 422 if (BD->isVariadic()) 423 return false; 424 } 425 else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 426 if (FD->isVariadic()) 427 return false; 428 } 429 430 if (getContext().getLangOpts().CPlusPlus) { 431 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 432 // Conditionally allow the inlining of template functions. 433 if (!getAnalysisManager().options.mayInlineTemplateFunctions()) 434 if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate) 435 return false; 436 437 // Conditionally allow the inlining of C++ standard library functions. 438 if (!getAnalysisManager().options.mayInlineCXXStandardLibrary()) 439 if (getContext().getSourceManager().isInSystemHeader(FD->getLocation())) 440 if (IsInStdNamespace(FD)) 441 return false; 442 } 443 } 444 445 // It is possible that the live variables analysis cannot be 446 // run. If so, bail out. 447 if (!CalleeADC->getAnalysis<RelaxedLiveVariables>()) 448 return false; 449 450 return true; 451} 452 453// The GDM component containing the dynamic dispatch bifurcation info. When 454// the exact type of the receiver is not known, we want to explore both paths - 455// one on which we do inline it and the other one on which we don't. This is 456// done to ensure we do not drop coverage. 457// This is the map from the receiver region to a bool, specifying either we 458// consider this region's information precise or not along the given path. 459namespace { 460 enum DynamicDispatchMode { 461 DynamicDispatchModeInlined = 1, 462 DynamicDispatchModeConservative 463 }; 464} 465REGISTER_TRAIT_WITH_PROGRAMSTATE(DynamicDispatchBifurcationMap, 466 CLANG_ENTO_PROGRAMSTATE_MAP(const MemRegion *, 467 unsigned)) 468 469bool ExprEngine::inlineCall(const CallEvent &Call, const Decl *D, 470 NodeBuilder &Bldr, ExplodedNode *Pred, 471 ProgramStateRef State) { 472 assert(D); 473 474 const LocationContext *CurLC = Pred->getLocationContext(); 475 const StackFrameContext *CallerSFC = CurLC->getCurrentStackFrame(); 476 const LocationContext *ParentOfCallee = 0; 477 478 AnalyzerOptions &Opts = getAnalysisManager().options; 479 480 // FIXME: Refactor this check into a hypothetical CallEvent::canInline. 481 switch (Call.getKind()) { 482 case CE_Function: 483 break; 484 case CE_CXXMember: 485 case CE_CXXMemberOperator: 486 if (!Opts.mayInlineCXXMemberFunction(CIMK_MemberFunctions)) 487 return false; 488 break; 489 case CE_CXXConstructor: { 490 if (!Opts.mayInlineCXXMemberFunction(CIMK_Constructors)) 491 return false; 492 493 const CXXConstructorCall &Ctor = cast<CXXConstructorCall>(Call); 494 495 // FIXME: We don't handle constructors or destructors for arrays properly. 496 const MemRegion *Target = Ctor.getCXXThisVal().getAsRegion(); 497 if (Target && isa<ElementRegion>(Target)) 498 return false; 499 500 // FIXME: This is a hack. We don't use the correct region for a new 501 // expression, so if we inline the constructor its result will just be 502 // thrown away. This short-term hack is tracked in <rdar://problem/12180598> 503 // and the longer-term possible fix is discussed in PR12014. 504 const CXXConstructExpr *CtorExpr = Ctor.getOriginExpr(); 505 if (const Stmt *Parent = CurLC->getParentMap().getParent(CtorExpr)) 506 if (isa<CXXNewExpr>(Parent)) 507 return false; 508 509 // Inlining constructors requires including initializers in the CFG. 510 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 511 assert(ADC->getCFGBuildOptions().AddInitializers && "No CFG initializers"); 512 (void)ADC; 513 514 // If the destructor is trivial, it's always safe to inline the constructor. 515 if (Ctor.getDecl()->getParent()->hasTrivialDestructor()) 516 break; 517 518 // For other types, only inline constructors if destructor inlining is 519 // also enabled. 520 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 521 return false; 522 523 // FIXME: This is a hack. We don't handle temporary destructors 524 // right now, so we shouldn't inline their constructors. 525 if (CtorExpr->getConstructionKind() == CXXConstructExpr::CK_Complete) 526 if (!Target || !isa<DeclRegion>(Target)) 527 return false; 528 529 break; 530 } 531 case CE_CXXDestructor: { 532 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 533 return false; 534 535 // Inlining destructors requires building the CFG correctly. 536 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 537 assert(ADC->getCFGBuildOptions().AddImplicitDtors && "No CFG destructors"); 538 (void)ADC; 539 540 const CXXDestructorCall &Dtor = cast<CXXDestructorCall>(Call); 541 542 // FIXME: We don't handle constructors or destructors for arrays properly. 543 const MemRegion *Target = Dtor.getCXXThisVal().getAsRegion(); 544 if (Target && isa<ElementRegion>(Target)) 545 return false; 546 547 break; 548 } 549 case CE_CXXAllocator: 550 // Do not inline allocators until we model deallocators. 551 // This is unfortunate, but basically necessary for smart pointers and such. 552 return false; 553 case CE_Block: { 554 const BlockDataRegion *BR = cast<BlockCall>(Call).getBlockRegion(); 555 assert(BR && "If we have the block definition we should have its region"); 556 AnalysisDeclContext *BlockCtx = AMgr.getAnalysisDeclContext(D); 557 ParentOfCallee = BlockCtx->getBlockInvocationContext(CallerSFC, 558 cast<BlockDecl>(D), 559 BR); 560 break; 561 } 562 case CE_ObjCMessage: 563 if (!Opts.mayInlineObjCMethod()) 564 return false; 565 if (!(getAnalysisManager().options.IPAMode == DynamicDispatch || 566 getAnalysisManager().options.IPAMode == DynamicDispatchBifurcate)) 567 return false; 568 break; 569 } 570 571 if (!shouldInlineDecl(D, Pred)) 572 return false; 573 574 if (!ParentOfCallee) 575 ParentOfCallee = CallerSFC; 576 577 // This may be NULL, but that's fine. 578 const Expr *CallE = Call.getOriginExpr(); 579 580 // Construct a new stack frame for the callee. 581 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); 582 const StackFrameContext *CalleeSFC = 583 CalleeADC->getStackFrame(ParentOfCallee, CallE, 584 currBldrCtx->getBlock(), 585 currStmtIdx); 586 587 CallEnter Loc(CallE, CalleeSFC, CurLC); 588 589 // Construct a new state which contains the mapping from actual to 590 // formal arguments. 591 State = State->enterStackFrame(Call, CalleeSFC); 592 593 bool isNew; 594 if (ExplodedNode *N = G.getNode(Loc, State, false, &isNew)) { 595 N->addPredecessor(Pred, G); 596 if (isNew) 597 Engine.getWorkList()->enqueue(N); 598 } 599 600 // If we decided to inline the call, the successor has been manually 601 // added onto the work list so remove it from the node builder. 602 Bldr.takeNodes(Pred); 603 604 NumInlinedCalls++; 605 606 // Mark the decl as visited. 607 if (VisitedCallees) 608 VisitedCallees->insert(D); 609 610 return true; 611} 612 613static ProgramStateRef getInlineFailedState(ProgramStateRef State, 614 const Stmt *CallE) { 615 void *ReplayState = State->get<ReplayWithoutInlining>(); 616 if (!ReplayState) 617 return 0; 618 619 assert(ReplayState == (const void*)CallE && "Backtracked to the wrong call."); 620 (void)CallE; 621 622 return State->remove<ReplayWithoutInlining>(); 623} 624 625void ExprEngine::VisitCallExpr(const CallExpr *CE, ExplodedNode *Pred, 626 ExplodedNodeSet &dst) { 627 // Perform the previsit of the CallExpr. 628 ExplodedNodeSet dstPreVisit; 629 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, CE, *this); 630 631 // Get the call in its initial state. We use this as a template to perform 632 // all the checks. 633 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 634 CallEventRef<> CallTemplate 635 = CEMgr.getSimpleCall(CE, Pred->getState(), Pred->getLocationContext()); 636 637 // Evaluate the function call. We try each of the checkers 638 // to see if the can evaluate the function call. 639 ExplodedNodeSet dstCallEvaluated; 640 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 641 I != E; ++I) { 642 evalCall(dstCallEvaluated, *I, *CallTemplate); 643 } 644 645 // Finally, perform the post-condition check of the CallExpr and store 646 // the created nodes in 'Dst'. 647 // Note that if the call was inlined, dstCallEvaluated will be empty. 648 // The post-CallExpr check will occur in processCallExit. 649 getCheckerManager().runCheckersForPostStmt(dst, dstCallEvaluated, CE, 650 *this); 651} 652 653void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred, 654 const CallEvent &Call) { 655 // WARNING: At this time, the state attached to 'Call' may be older than the 656 // state in 'Pred'. This is a minor optimization since CheckerManager will 657 // use an updated CallEvent instance when calling checkers, but if 'Call' is 658 // ever used directly in this function all callers should be updated to pass 659 // the most recent state. (It is probably not worth doing the work here since 660 // for some callers this will not be necessary.) 661 662 // Run any pre-call checks using the generic call interface. 663 ExplodedNodeSet dstPreVisit; 664 getCheckerManager().runCheckersForPreCall(dstPreVisit, Pred, Call, *this); 665 666 // Actually evaluate the function call. We try each of the checkers 667 // to see if the can evaluate the function call, and get a callback at 668 // defaultEvalCall if all of them fail. 669 ExplodedNodeSet dstCallEvaluated; 670 getCheckerManager().runCheckersForEvalCall(dstCallEvaluated, dstPreVisit, 671 Call, *this); 672 673 // Finally, run any post-call checks. 674 getCheckerManager().runCheckersForPostCall(Dst, dstCallEvaluated, 675 Call, *this); 676} 677 678ProgramStateRef ExprEngine::bindReturnValue(const CallEvent &Call, 679 const LocationContext *LCtx, 680 ProgramStateRef State) { 681 const Expr *E = Call.getOriginExpr(); 682 if (!E) 683 return State; 684 685 // Some method families have known return values. 686 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) { 687 switch (Msg->getMethodFamily()) { 688 default: 689 break; 690 case OMF_autorelease: 691 case OMF_retain: 692 case OMF_self: { 693 // These methods return their receivers. 694 return State->BindExpr(E, LCtx, Msg->getReceiverSVal()); 695 } 696 } 697 } else if (const CXXConstructorCall *C = dyn_cast<CXXConstructorCall>(&Call)){ 698 return State->BindExpr(E, LCtx, C->getCXXThisVal()); 699 } 700 701 // Conjure a symbol if the return value is unknown. 702 QualType ResultTy = Call.getResultType(); 703 SValBuilder &SVB = getSValBuilder(); 704 unsigned Count = currBldrCtx->blockCount(); 705 SVal R = SVB.conjureSymbolVal(0, E, LCtx, ResultTy, Count); 706 return State->BindExpr(E, LCtx, R); 707} 708 709// Conservatively evaluate call by invalidating regions and binding 710// a conjured return value. 711void ExprEngine::conservativeEvalCall(const CallEvent &Call, NodeBuilder &Bldr, 712 ExplodedNode *Pred, ProgramStateRef State) { 713 State = Call.invalidateRegions(currBldrCtx->blockCount(), State); 714 State = bindReturnValue(Call, Pred->getLocationContext(), State); 715 716 // And make the result node. 717 Bldr.generateNode(Call.getProgramPoint(), State, Pred); 718} 719 720void ExprEngine::defaultEvalCall(NodeBuilder &Bldr, ExplodedNode *Pred, 721 const CallEvent &CallTemplate) { 722 // Make sure we have the most recent state attached to the call. 723 ProgramStateRef State = Pred->getState(); 724 CallEventRef<> Call = CallTemplate.cloneWithState(State); 725 726 if (!getAnalysisManager().shouldInlineCall()) { 727 conservativeEvalCall(*Call, Bldr, Pred, State); 728 return; 729 } 730 // Try to inline the call. 731 // The origin expression here is just used as a kind of checksum; 732 // this should still be safe even for CallEvents that don't come from exprs. 733 const Expr *E = Call->getOriginExpr(); 734 ProgramStateRef InlinedFailedState = getInlineFailedState(State, E); 735 736 if (InlinedFailedState) { 737 // If we already tried once and failed, make sure we don't retry later. 738 State = InlinedFailedState; 739 } else { 740 RuntimeDefinition RD = Call->getRuntimeDefinition(); 741 const Decl *D = RD.getDecl(); 742 if (D) { 743 if (RD.mayHaveOtherDefinitions()) { 744 // Explore with and without inlining the call. 745 if (getAnalysisManager().options.IPAMode == DynamicDispatchBifurcate) { 746 BifurcateCall(RD.getDispatchRegion(), *Call, D, Bldr, Pred); 747 return; 748 } 749 750 // Don't inline if we're not in any dynamic dispatch mode. 751 if (getAnalysisManager().options.IPAMode != DynamicDispatch) { 752 conservativeEvalCall(*Call, Bldr, Pred, State); 753 return; 754 } 755 } 756 757 // We are not bifurcating and we do have a Decl, so just inline. 758 if (inlineCall(*Call, D, Bldr, Pred, State)) 759 return; 760 } 761 } 762 763 // If we can't inline it, handle the return value and invalidate the regions. 764 conservativeEvalCall(*Call, Bldr, Pred, State); 765} 766 767void ExprEngine::BifurcateCall(const MemRegion *BifurReg, 768 const CallEvent &Call, const Decl *D, 769 NodeBuilder &Bldr, ExplodedNode *Pred) { 770 assert(BifurReg); 771 BifurReg = BifurReg->StripCasts(); 772 773 // Check if we've performed the split already - note, we only want 774 // to split the path once per memory region. 775 ProgramStateRef State = Pred->getState(); 776 const unsigned *BState = 777 State->get<DynamicDispatchBifurcationMap>(BifurReg); 778 if (BState) { 779 // If we are on "inline path", keep inlining if possible. 780 if (*BState == DynamicDispatchModeInlined) 781 if (inlineCall(Call, D, Bldr, Pred, State)) 782 return; 783 // If inline failed, or we are on the path where we assume we 784 // don't have enough info about the receiver to inline, conjure the 785 // return value and invalidate the regions. 786 conservativeEvalCall(Call, Bldr, Pred, State); 787 return; 788 } 789 790 // If we got here, this is the first time we process a message to this 791 // region, so split the path. 792 ProgramStateRef IState = 793 State->set<DynamicDispatchBifurcationMap>(BifurReg, 794 DynamicDispatchModeInlined); 795 inlineCall(Call, D, Bldr, Pred, IState); 796 797 ProgramStateRef NoIState = 798 State->set<DynamicDispatchBifurcationMap>(BifurReg, 799 DynamicDispatchModeConservative); 800 conservativeEvalCall(Call, Bldr, Pred, NoIState); 801 802 NumOfDynamicDispatchPathSplits++; 803 return; 804} 805 806 807void ExprEngine::VisitReturnStmt(const ReturnStmt *RS, ExplodedNode *Pred, 808 ExplodedNodeSet &Dst) { 809 810 ExplodedNodeSet dstPreVisit; 811 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, RS, *this); 812 813 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 814 815 if (RS->getRetValue()) { 816 for (ExplodedNodeSet::iterator it = dstPreVisit.begin(), 817 ei = dstPreVisit.end(); it != ei; ++it) { 818 B.generateNode(RS, *it, (*it)->getState()); 819 } 820 } 821} 822