ExprEngineCallAndReturn.cpp revision 57330eed3fbe530cb05996e4a346cc5fc217c0d9
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/DeclCXX.h" 21#include "clang/AST/ParentMap.h" 22#include "llvm/ADT/SmallSet.h" 23#include "llvm/ADT/Statistic.h" 24#include "llvm/Support/SaveAndRestore.h" 25 26using namespace clang; 27using namespace ento; 28 29STATISTIC(NumOfDynamicDispatchPathSplits, 30 "The # of times we split the path due to imprecise dynamic dispatch info"); 31 32STATISTIC(NumInlinedCalls, 33 "The # of times we inlined a call"); 34 35void ExprEngine::processCallEnter(CallEnter CE, ExplodedNode *Pred) { 36 // Get the entry block in the CFG of the callee. 37 const StackFrameContext *calleeCtx = CE.getCalleeContext(); 38 const CFG *CalleeCFG = calleeCtx->getCFG(); 39 const CFGBlock *Entry = &(CalleeCFG->getEntry()); 40 41 // Validate the CFG. 42 assert(Entry->empty()); 43 assert(Entry->succ_size() == 1); 44 45 // Get the solitary sucessor. 46 const CFGBlock *Succ = *(Entry->succ_begin()); 47 48 // Construct an edge representing the starting location in the callee. 49 BlockEdge Loc(Entry, Succ, calleeCtx); 50 51 ProgramStateRef state = Pred->getState(); 52 53 // Construct a new node and add it to the worklist. 54 bool isNew; 55 ExplodedNode *Node = G.getNode(Loc, state, false, &isNew); 56 Node->addPredecessor(Pred, G); 57 if (isNew) 58 Engine.getWorkList()->enqueue(Node); 59} 60 61// Find the last statement on the path to the exploded node and the 62// corresponding Block. 63static std::pair<const Stmt*, 64 const CFGBlock*> getLastStmt(const ExplodedNode *Node) { 65 const Stmt *S = 0; 66 const StackFrameContext *SF = 67 Node->getLocation().getLocationContext()->getCurrentStackFrame(); 68 69 // Back up through the ExplodedGraph until we reach a statement node in this 70 // stack frame. 71 while (Node) { 72 const ProgramPoint &PP = Node->getLocation(); 73 74 if (PP.getLocationContext()->getCurrentStackFrame() == SF) { 75 if (const StmtPoint *SP = dyn_cast<StmtPoint>(&PP)) { 76 S = SP->getStmt(); 77 break; 78 } else if (const CallExitEnd *CEE = dyn_cast<CallExitEnd>(&PP)) { 79 S = CEE->getCalleeContext()->getCallSite(); 80 if (S) 81 break; 82 83 // If there is no statement, this is an implicitly-generated call. 84 // We'll walk backwards over it and then continue the loop to find 85 // an actual statement. 86 const CallEnter *CE; 87 do { 88 Node = Node->getFirstPred(); 89 CE = Node->getLocationAs<CallEnter>(); 90 } while (!CE || CE->getCalleeContext() != CEE->getCalleeContext()); 91 92 // Continue searching the graph. 93 } 94 } else if (const CallEnter *CE = dyn_cast<CallEnter>(&PP)) { 95 // If we reached the CallEnter for this function, it has no statements. 96 if (CE->getCalleeContext() == SF) 97 break; 98 } 99 100 Node = *Node->pred_begin(); 101 } 102 103 const CFGBlock *Blk = 0; 104 if (S) { 105 // Now, get the enclosing basic block. 106 while (Node && Node->pred_size() >=1 ) { 107 const ProgramPoint &PP = Node->getLocation(); 108 if (isa<BlockEdge>(PP) && 109 (PP.getLocationContext()->getCurrentStackFrame() == SF)) { 110 BlockEdge &EPP = cast<BlockEdge>(PP); 111 Blk = EPP.getDst(); 112 break; 113 } 114 Node = *Node->pred_begin(); 115 } 116 } 117 118 return std::pair<const Stmt*, const CFGBlock*>(S, Blk); 119} 120 121/// The call exit is simulated with a sequence of nodes, which occur between 122/// CallExitBegin and CallExitEnd. The following operations occur between the 123/// two program points: 124/// 1. CallExitBegin (triggers the start of call exit sequence) 125/// 2. Bind the return value 126/// 3. Run Remove dead bindings to clean up the dead symbols from the callee. 127/// 4. CallExitEnd (switch to the caller context) 128/// 5. PostStmt<CallExpr> 129void ExprEngine::processCallExit(ExplodedNode *CEBNode) { 130 // Step 1 CEBNode was generated before the call. 131 132 const StackFrameContext *calleeCtx = 133 CEBNode->getLocationContext()->getCurrentStackFrame(); 134 135 // The parent context might not be a stack frame, so make sure we 136 // look up the first enclosing stack frame. 137 const StackFrameContext *callerCtx = 138 calleeCtx->getParent()->getCurrentStackFrame(); 139 140 const Stmt *CE = calleeCtx->getCallSite(); 141 ProgramStateRef state = CEBNode->getState(); 142 // Find the last statement in the function and the corresponding basic block. 143 const Stmt *LastSt = 0; 144 const CFGBlock *Blk = 0; 145 llvm::tie(LastSt, Blk) = getLastStmt(CEBNode); 146 147 // Step 2: generate node with bound return value: CEBNode -> BindedRetNode. 148 149 // If the callee returns an expression, bind its value to CallExpr. 150 if (CE) { 151 if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) { 152 const LocationContext *LCtx = CEBNode->getLocationContext(); 153 SVal V = state->getSVal(RS, LCtx); 154 state = state->BindExpr(CE, callerCtx, V); 155 } 156 157 // Bind the constructed object value to CXXConstructExpr. 158 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(CE)) { 159 loc::MemRegionVal This = 160 svalBuilder.getCXXThis(CCE->getConstructor()->getParent(), calleeCtx); 161 SVal ThisV = state->getSVal(This); 162 163 // Always bind the region to the CXXConstructExpr. 164 state = state->BindExpr(CCE, callerCtx, ThisV); 165 } 166 } 167 168 // Generate a CallEvent /before/ cleaning the state, so that we can get the 169 // correct value for 'this' (if necessary). 170 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 171 CallEventRef<> Call = CEMgr.getCaller(calleeCtx, state); 172 173 // Step 3: BindedRetNode -> CleanedNodes 174 // If we can find a statement and a block in the inlined function, run remove 175 // dead bindings before returning from the call. This is important to ensure 176 // that we report the issues such as leaks in the stack contexts in which 177 // they occurred. 178 ExplodedNodeSet CleanedNodes; 179 if (LastSt && Blk && AMgr.options.AnalysisPurgeOpt != PurgeNone) { 180 static SimpleProgramPointTag retValBind("ExprEngine : Bind Return Value"); 181 PostStmt Loc(LastSt, calleeCtx, &retValBind); 182 bool isNew; 183 ExplodedNode *BindedRetNode = G.getNode(Loc, state, false, &isNew); 184 BindedRetNode->addPredecessor(CEBNode, G); 185 if (!isNew) 186 return; 187 188 NodeBuilderContext Ctx(getCoreEngine(), Blk, BindedRetNode); 189 currBldrCtx = &Ctx; 190 // Here, we call the Symbol Reaper with 0 statement and caller location 191 // context, telling it to clean up everything in the callee's context 192 // (and it's children). We use LastStmt as a diagnostic statement, which 193 // which the PreStmtPurge Dead point will be associated. 194 removeDead(BindedRetNode, CleanedNodes, 0, callerCtx, LastSt, 195 ProgramPoint::PostStmtPurgeDeadSymbolsKind); 196 currBldrCtx = 0; 197 } else { 198 CleanedNodes.Add(CEBNode); 199 } 200 201 for (ExplodedNodeSet::iterator I = CleanedNodes.begin(), 202 E = CleanedNodes.end(); I != E; ++I) { 203 204 // Step 4: Generate the CallExit and leave the callee's context. 205 // CleanedNodes -> CEENode 206 CallExitEnd Loc(calleeCtx, callerCtx); 207 bool isNew; 208 ProgramStateRef CEEState = (*I == CEBNode) ? state : (*I)->getState(); 209 ExplodedNode *CEENode = G.getNode(Loc, CEEState, false, &isNew); 210 CEENode->addPredecessor(*I, G); 211 if (!isNew) 212 return; 213 214 // Step 5: Perform the post-condition check of the CallExpr and enqueue the 215 // result onto the work list. 216 // CEENode -> Dst -> WorkList 217 NodeBuilderContext Ctx(Engine, calleeCtx->getCallSiteBlock(), CEENode); 218 SaveAndRestore<const NodeBuilderContext*> NBCSave(currBldrCtx, 219 &Ctx); 220 SaveAndRestore<unsigned> CBISave(currStmtIdx, calleeCtx->getIndex()); 221 222 CallEventRef<> UpdatedCall = Call.cloneWithState(CEEState); 223 224 ExplodedNodeSet DstPostCall; 225 getCheckerManager().runCheckersForPostCall(DstPostCall, CEENode, 226 *UpdatedCall, *this, 227 /*WasInlined=*/true); 228 229 ExplodedNodeSet Dst; 230 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) { 231 getCheckerManager().runCheckersForPostObjCMessage(Dst, DstPostCall, *Msg, 232 *this, 233 /*WasInlined=*/true); 234 } else if (CE) { 235 getCheckerManager().runCheckersForPostStmt(Dst, DstPostCall, CE, 236 *this, /*WasInlined=*/true); 237 } else { 238 Dst.insert(DstPostCall); 239 } 240 241 // Enqueue the next element in the block. 242 for (ExplodedNodeSet::iterator PSI = Dst.begin(), PSE = Dst.end(); 243 PSI != PSE; ++PSI) { 244 Engine.getWorkList()->enqueue(*PSI, calleeCtx->getCallSiteBlock(), 245 calleeCtx->getIndex()+1); 246 } 247 } 248} 249 250static void examineStackFrames(const Decl *D, const LocationContext *LCtx, 251 bool &IsRecursive, unsigned &StackDepth) { 252 IsRecursive = false; 253 StackDepth = 0; 254 while (LCtx) { 255 if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LCtx)) { 256 ++StackDepth; 257 if (SFC->getDecl() == D) 258 IsRecursive = true; 259 } 260 LCtx = LCtx->getParent(); 261 } 262} 263 264static bool IsInStdNamespace(const FunctionDecl *FD) { 265 const DeclContext *DC = FD->getEnclosingNamespaceContext(); 266 const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC); 267 if (!ND) 268 return false; 269 270 while (const DeclContext *Parent = ND->getParent()) { 271 if (!isa<NamespaceDecl>(Parent)) 272 break; 273 ND = cast<NamespaceDecl>(Parent); 274 } 275 276 return ND->getName() == "std"; 277} 278 279// Determine if we should inline the call. 280bool ExprEngine::shouldInlineDecl(const Decl *D, ExplodedNode *Pred) { 281 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); 282 const CFG *CalleeCFG = CalleeADC->getCFG(); 283 284 // It is possible that the CFG cannot be constructed. 285 // Be safe, and check if the CalleeCFG is valid. 286 if (!CalleeCFG) 287 return false; 288 289 bool IsRecursive = false; 290 unsigned StackDepth = 0; 291 examineStackFrames(D, Pred->getLocationContext(), IsRecursive, StackDepth); 292 if ((StackDepth >= AMgr.options.InlineMaxStackDepth) && 293 ((CalleeCFG->getNumBlockIDs() > AMgr.options.getAlwaysInlineSize()) 294 || IsRecursive)) 295 return false; 296 297 if (Engine.FunctionSummaries->hasReachedMaxBlockCount(D)) 298 return false; 299 300 if (CalleeCFG->getNumBlockIDs() > AMgr.options.InlineMaxFunctionSize) 301 return false; 302 303 // Do not inline variadic calls (for now). 304 if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) { 305 if (BD->isVariadic()) 306 return false; 307 } 308 else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 309 if (FD->isVariadic()) 310 return false; 311 } 312 313 if (getContext().getLangOpts().CPlusPlus) { 314 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 315 // Conditionally allow the inlining of template functions. 316 if (!getAnalysisManager().options.mayInlineTemplateFunctions()) 317 if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate) 318 return false; 319 320 // Conditionally allow the inlining of C++ standard library functions. 321 if (!getAnalysisManager().options.mayInlineCXXStandardLibrary()) 322 if (getContext().getSourceManager().isInSystemHeader(FD->getLocation())) 323 if (IsInStdNamespace(FD)) 324 return false; 325 } 326 } 327 328 // It is possible that the live variables analysis cannot be 329 // run. If so, bail out. 330 if (!CalleeADC->getAnalysis<RelaxedLiveVariables>()) 331 return false; 332 333 return true; 334} 335 336/// The GDM component containing the dynamic dispatch bifurcation info. When 337/// the exact type of the receiver is not known, we want to explore both paths - 338/// one on which we do inline it and the other one on which we don't. This is 339/// done to ensure we do not drop coverage. 340/// This is the map from the receiver region to a bool, specifying either we 341/// consider this region's information precise or not along the given path. 342namespace clang { 343namespace ento { 344enum DynamicDispatchMode { DynamicDispatchModeInlined = 1, 345 DynamicDispatchModeConservative }; 346 347struct DynamicDispatchBifurcationMap {}; 348typedef llvm::ImmutableMap<const MemRegion*, 349 unsigned int> DynamicDispatchBifur; 350template<> struct ProgramStateTrait<DynamicDispatchBifurcationMap> 351 : public ProgramStatePartialTrait<DynamicDispatchBifur> { 352 static void *GDMIndex() { static int index; return &index; } 353}; 354 355}} 356 357bool ExprEngine::inlineCall(const CallEvent &Call, const Decl *D, 358 NodeBuilder &Bldr, ExplodedNode *Pred, 359 ProgramStateRef State) { 360 assert(D); 361 362 const LocationContext *CurLC = Pred->getLocationContext(); 363 const StackFrameContext *CallerSFC = CurLC->getCurrentStackFrame(); 364 const LocationContext *ParentOfCallee = 0; 365 366 const AnalyzerOptions &Opts = getAnalysisManager().options; 367 368 // FIXME: Refactor this check into a hypothetical CallEvent::canInline. 369 switch (Call.getKind()) { 370 case CE_Function: 371 break; 372 case CE_CXXMember: 373 case CE_CXXMemberOperator: 374 if (!Opts.mayInlineCXXMemberFunction(CIMK_MemberFunctions)) 375 return false; 376 break; 377 case CE_CXXConstructor: { 378 if (!Opts.mayInlineCXXMemberFunction(CIMK_Constructors)) 379 return false; 380 381 const CXXConstructorCall &Ctor = cast<CXXConstructorCall>(Call); 382 383 // FIXME: We don't handle constructors or destructors for arrays properly. 384 const MemRegion *Target = Ctor.getCXXThisVal().getAsRegion(); 385 if (Target && isa<ElementRegion>(Target)) 386 return false; 387 388 // FIXME: This is a hack. We don't use the correct region for a new 389 // expression, so if we inline the constructor its result will just be 390 // thrown away. This short-term hack is tracked in <rdar://problem/12180598> 391 // and the longer-term possible fix is discussed in PR12014. 392 const CXXConstructExpr *CtorExpr = Ctor.getOriginExpr(); 393 if (const Stmt *Parent = CurLC->getParentMap().getParent(CtorExpr)) 394 if (isa<CXXNewExpr>(Parent)) 395 return false; 396 397 // Inlining constructors requires including initializers in the CFG. 398 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 399 assert(ADC->getCFGBuildOptions().AddInitializers && "No CFG initializers"); 400 (void)ADC; 401 402 // If the destructor is trivial, it's always safe to inline the constructor. 403 if (Ctor.getDecl()->getParent()->hasTrivialDestructor()) 404 break; 405 406 // For other types, only inline constructors if destructor inlining is 407 // also enabled. 408 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 409 return false; 410 411 // FIXME: This is a hack. We don't handle temporary destructors 412 // right now, so we shouldn't inline their constructors. 413 if (CtorExpr->getConstructionKind() == CXXConstructExpr::CK_Complete) 414 if (!Target || !isa<DeclRegion>(Target)) 415 return false; 416 417 break; 418 } 419 case CE_CXXDestructor: { 420 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 421 return false; 422 423 // Inlining destructors requires building the CFG correctly. 424 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 425 assert(ADC->getCFGBuildOptions().AddImplicitDtors && "No CFG destructors"); 426 (void)ADC; 427 428 const CXXDestructorCall &Dtor = cast<CXXDestructorCall>(Call); 429 430 // FIXME: We don't handle constructors or destructors for arrays properly. 431 const MemRegion *Target = Dtor.getCXXThisVal().getAsRegion(); 432 if (Target && isa<ElementRegion>(Target)) 433 return false; 434 435 break; 436 } 437 case CE_CXXAllocator: 438 // Do not inline allocators until we model deallocators. 439 // This is unfortunate, but basically necessary for smart pointers and such. 440 return false; 441 case CE_Block: { 442 const BlockDataRegion *BR = cast<BlockCall>(Call).getBlockRegion(); 443 assert(BR && "If we have the block definition we should have its region"); 444 AnalysisDeclContext *BlockCtx = AMgr.getAnalysisDeclContext(D); 445 ParentOfCallee = BlockCtx->getBlockInvocationContext(CallerSFC, 446 cast<BlockDecl>(D), 447 BR); 448 break; 449 } 450 case CE_ObjCMessage: 451 if (!Opts.mayInlineObjCMethod()) 452 return false; 453 if (!(getAnalysisManager().options.IPAMode == DynamicDispatch || 454 getAnalysisManager().options.IPAMode == DynamicDispatchBifurcate)) 455 return false; 456 break; 457 } 458 459 if (!shouldInlineDecl(D, Pred)) 460 return false; 461 462 if (!ParentOfCallee) 463 ParentOfCallee = CallerSFC; 464 465 // This may be NULL, but that's fine. 466 const Expr *CallE = Call.getOriginExpr(); 467 468 // Construct a new stack frame for the callee. 469 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); 470 const StackFrameContext *CalleeSFC = 471 CalleeADC->getStackFrame(ParentOfCallee, CallE, 472 currBldrCtx->getBlock(), 473 currStmtIdx); 474 475 CallEnter Loc(CallE, CalleeSFC, CurLC); 476 477 // Construct a new state which contains the mapping from actual to 478 // formal arguments. 479 State = State->enterStackFrame(Call, CalleeSFC); 480 481 bool isNew; 482 if (ExplodedNode *N = G.getNode(Loc, State, false, &isNew)) { 483 N->addPredecessor(Pred, G); 484 if (isNew) 485 Engine.getWorkList()->enqueue(N); 486 } 487 488 // If we decided to inline the call, the successor has been manually 489 // added onto the work list so remove it from the node builder. 490 Bldr.takeNodes(Pred); 491 492 NumInlinedCalls++; 493 494 // Mark the decl as visited. 495 if (VisitedCallees) 496 VisitedCallees->insert(D); 497 498 return true; 499} 500 501static ProgramStateRef getInlineFailedState(ProgramStateRef State, 502 const Stmt *CallE) { 503 void *ReplayState = State->get<ReplayWithoutInlining>(); 504 if (!ReplayState) 505 return 0; 506 507 assert(ReplayState == (const void*)CallE && "Backtracked to the wrong call."); 508 (void)CallE; 509 510 return State->remove<ReplayWithoutInlining>(); 511} 512 513void ExprEngine::VisitCallExpr(const CallExpr *CE, ExplodedNode *Pred, 514 ExplodedNodeSet &dst) { 515 // Perform the previsit of the CallExpr. 516 ExplodedNodeSet dstPreVisit; 517 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, CE, *this); 518 519 // Get the call in its initial state. We use this as a template to perform 520 // all the checks. 521 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 522 CallEventRef<> CallTemplate 523 = CEMgr.getSimpleCall(CE, Pred->getState(), Pred->getLocationContext()); 524 525 // Evaluate the function call. We try each of the checkers 526 // to see if the can evaluate the function call. 527 ExplodedNodeSet dstCallEvaluated; 528 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 529 I != E; ++I) { 530 evalCall(dstCallEvaluated, *I, *CallTemplate); 531 } 532 533 // Finally, perform the post-condition check of the CallExpr and store 534 // the created nodes in 'Dst'. 535 // Note that if the call was inlined, dstCallEvaluated will be empty. 536 // The post-CallExpr check will occur in processCallExit. 537 getCheckerManager().runCheckersForPostStmt(dst, dstCallEvaluated, CE, 538 *this); 539} 540 541void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred, 542 const CallEvent &Call) { 543 // WARNING: At this time, the state attached to 'Call' may be older than the 544 // state in 'Pred'. This is a minor optimization since CheckerManager will 545 // use an updated CallEvent instance when calling checkers, but if 'Call' is 546 // ever used directly in this function all callers should be updated to pass 547 // the most recent state. (It is probably not worth doing the work here since 548 // for some callers this will not be necessary.) 549 550 // Run any pre-call checks using the generic call interface. 551 ExplodedNodeSet dstPreVisit; 552 getCheckerManager().runCheckersForPreCall(dstPreVisit, Pred, Call, *this); 553 554 // Actually evaluate the function call. We try each of the checkers 555 // to see if the can evaluate the function call, and get a callback at 556 // defaultEvalCall if all of them fail. 557 ExplodedNodeSet dstCallEvaluated; 558 getCheckerManager().runCheckersForEvalCall(dstCallEvaluated, dstPreVisit, 559 Call, *this); 560 561 // Finally, run any post-call checks. 562 getCheckerManager().runCheckersForPostCall(Dst, dstCallEvaluated, 563 Call, *this); 564} 565 566ProgramStateRef ExprEngine::bindReturnValue(const CallEvent &Call, 567 const LocationContext *LCtx, 568 ProgramStateRef State) { 569 const Expr *E = Call.getOriginExpr(); 570 if (!E) 571 return State; 572 573 // Some method families have known return values. 574 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) { 575 switch (Msg->getMethodFamily()) { 576 default: 577 break; 578 case OMF_autorelease: 579 case OMF_retain: 580 case OMF_self: { 581 // These methods return their receivers. 582 return State->BindExpr(E, LCtx, Msg->getReceiverSVal()); 583 } 584 } 585 } else if (const CXXConstructorCall *C = dyn_cast<CXXConstructorCall>(&Call)){ 586 return State->BindExpr(E, LCtx, C->getCXXThisVal()); 587 } 588 589 // Conjure a symbol if the return value is unknown. 590 QualType ResultTy = Call.getResultType(); 591 SValBuilder &SVB = getSValBuilder(); 592 unsigned Count = currBldrCtx->blockCount(); 593 SVal R = SVB.conjureSymbolVal(0, E, LCtx, ResultTy, Count); 594 return State->BindExpr(E, LCtx, R); 595} 596 597// Conservatively evaluate call by invalidating regions and binding 598// a conjured return value. 599void ExprEngine::conservativeEvalCall(const CallEvent &Call, NodeBuilder &Bldr, 600 ExplodedNode *Pred, ProgramStateRef State) { 601 State = Call.invalidateRegions(currBldrCtx->blockCount(), State); 602 State = bindReturnValue(Call, Pred->getLocationContext(), State); 603 604 // And make the result node. 605 Bldr.generateNode(Call.getProgramPoint(), State, Pred); 606} 607 608void ExprEngine::defaultEvalCall(NodeBuilder &Bldr, ExplodedNode *Pred, 609 const CallEvent &CallTemplate) { 610 // Make sure we have the most recent state attached to the call. 611 ProgramStateRef State = Pred->getState(); 612 CallEventRef<> Call = CallTemplate.cloneWithState(State); 613 614 if (!getAnalysisManager().shouldInlineCall()) { 615 conservativeEvalCall(*Call, Bldr, Pred, State); 616 return; 617 } 618 // Try to inline the call. 619 // The origin expression here is just used as a kind of checksum; 620 // this should still be safe even for CallEvents that don't come from exprs. 621 const Expr *E = Call->getOriginExpr(); 622 ProgramStateRef InlinedFailedState = getInlineFailedState(State, E); 623 624 if (InlinedFailedState) { 625 // If we already tried once and failed, make sure we don't retry later. 626 State = InlinedFailedState; 627 } else { 628 RuntimeDefinition RD = Call->getRuntimeDefinition(); 629 const Decl *D = RD.getDecl(); 630 if (D) { 631 if (RD.mayHaveOtherDefinitions()) { 632 // Explore with and without inlining the call. 633 if (getAnalysisManager().options.IPAMode == DynamicDispatchBifurcate) { 634 BifurcateCall(RD.getDispatchRegion(), *Call, D, Bldr, Pred); 635 return; 636 } 637 638 // Don't inline if we're not in any dynamic dispatch mode. 639 if (getAnalysisManager().options.IPAMode != DynamicDispatch) { 640 conservativeEvalCall(*Call, Bldr, Pred, State); 641 return; 642 } 643 } 644 645 // We are not bifurcating and we do have a Decl, so just inline. 646 if (inlineCall(*Call, D, Bldr, Pred, State)) 647 return; 648 } 649 } 650 651 // If we can't inline it, handle the return value and invalidate the regions. 652 conservativeEvalCall(*Call, Bldr, Pred, State); 653} 654 655void ExprEngine::BifurcateCall(const MemRegion *BifurReg, 656 const CallEvent &Call, const Decl *D, 657 NodeBuilder &Bldr, ExplodedNode *Pred) { 658 assert(BifurReg); 659 BifurReg = BifurReg->StripCasts(); 660 661 // Check if we've performed the split already - note, we only want 662 // to split the path once per memory region. 663 ProgramStateRef State = Pred->getState(); 664 const unsigned int *BState = 665 State->get<DynamicDispatchBifurcationMap>(BifurReg); 666 if (BState) { 667 // If we are on "inline path", keep inlining if possible. 668 if (*BState == DynamicDispatchModeInlined) 669 if (inlineCall(Call, D, Bldr, Pred, State)) 670 return; 671 // If inline failed, or we are on the path where we assume we 672 // don't have enough info about the receiver to inline, conjure the 673 // return value and invalidate the regions. 674 conservativeEvalCall(Call, Bldr, Pred, State); 675 return; 676 } 677 678 // If we got here, this is the first time we process a message to this 679 // region, so split the path. 680 ProgramStateRef IState = 681 State->set<DynamicDispatchBifurcationMap>(BifurReg, 682 DynamicDispatchModeInlined); 683 inlineCall(Call, D, Bldr, Pred, IState); 684 685 ProgramStateRef NoIState = 686 State->set<DynamicDispatchBifurcationMap>(BifurReg, 687 DynamicDispatchModeConservative); 688 conservativeEvalCall(Call, Bldr, Pred, NoIState); 689 690 NumOfDynamicDispatchPathSplits++; 691 return; 692} 693 694 695void ExprEngine::VisitReturnStmt(const ReturnStmt *RS, ExplodedNode *Pred, 696 ExplodedNodeSet &Dst) { 697 698 ExplodedNodeSet dstPreVisit; 699 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, RS, *this); 700 701 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 702 703 if (RS->getRetValue()) { 704 for (ExplodedNodeSet::iterator it = dstPreVisit.begin(), 705 ei = dstPreVisit.end(); it != ei; ++it) { 706 B.generateNode(RS, *it, (*it)->getState()); 707 } 708 } 709} 710