ExprEngineCallAndReturn.cpp revision 046e79a425bfa82b480b8a07ce11d96391fa0a9b
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 36STATISTIC(NumReachedInlineCountMax, 37 "The # of times we reached inline count maximum"); 38 39void ExprEngine::processCallEnter(CallEnter CE, ExplodedNode *Pred) { 40 // Get the entry block in the CFG of the callee. 41 const StackFrameContext *calleeCtx = CE.getCalleeContext(); 42 const CFG *CalleeCFG = calleeCtx->getCFG(); 43 const CFGBlock *Entry = &(CalleeCFG->getEntry()); 44 45 // Validate the CFG. 46 assert(Entry->empty()); 47 assert(Entry->succ_size() == 1); 48 49 // Get the solitary sucessor. 50 const CFGBlock *Succ = *(Entry->succ_begin()); 51 52 // Construct an edge representing the starting location in the callee. 53 BlockEdge Loc(Entry, Succ, calleeCtx); 54 55 ProgramStateRef state = Pred->getState(); 56 57 // Construct a new node and add it to the worklist. 58 bool isNew; 59 ExplodedNode *Node = G.getNode(Loc, state, false, &isNew); 60 Node->addPredecessor(Pred, G); 61 if (isNew) 62 Engine.getWorkList()->enqueue(Node); 63} 64 65// Find the last statement on the path to the exploded node and the 66// corresponding Block. 67static std::pair<const Stmt*, 68 const CFGBlock*> getLastStmt(const ExplodedNode *Node) { 69 const Stmt *S = 0; 70 const CFGBlock *Blk = 0; 71 const StackFrameContext *SF = 72 Node->getLocation().getLocationContext()->getCurrentStackFrame(); 73 74 // Back up through the ExplodedGraph until we reach a statement node in this 75 // stack frame. 76 while (Node) { 77 const ProgramPoint &PP = Node->getLocation(); 78 79 if (PP.getLocationContext()->getCurrentStackFrame() == SF) { 80 if (Optional<StmtPoint> SP = PP.getAs<StmtPoint>()) { 81 S = SP->getStmt(); 82 break; 83 } else if (Optional<CallExitEnd> CEE = PP.getAs<CallExitEnd>()) { 84 S = CEE->getCalleeContext()->getCallSite(); 85 if (S) 86 break; 87 88 // If there is no statement, this is an implicitly-generated call. 89 // We'll walk backwards over it and then continue the loop to find 90 // an actual statement. 91 Optional<CallEnter> CE; 92 do { 93 Node = Node->getFirstPred(); 94 CE = Node->getLocationAs<CallEnter>(); 95 } while (!CE || CE->getCalleeContext() != CEE->getCalleeContext()); 96 97 // Continue searching the graph. 98 } else if (Optional<BlockEdge> BE = PP.getAs<BlockEdge>()) { 99 Blk = BE->getSrc(); 100 } 101 } else if (Optional<CallEnter> CE = PP.getAs<CallEnter>()) { 102 // If we reached the CallEnter for this function, it has no statements. 103 if (CE->getCalleeContext() == SF) 104 break; 105 } 106 107 if (Node->pred_empty()) 108 return std::pair<const Stmt*, const CFGBlock*>((Stmt*)0, (CFGBlock*)0); 109 110 Node = *Node->pred_begin(); 111 } 112 113 return std::pair<const Stmt*, const CFGBlock*>(S, Blk); 114} 115 116/// Adjusts a return value when the called function's return type does not 117/// match the caller's expression type. This can happen when a dynamic call 118/// is devirtualized, and the overridding method has a covariant (more specific) 119/// return type than the parent's method. For C++ objects, this means we need 120/// to add base casts. 121static SVal adjustReturnValue(SVal V, QualType ExpectedTy, QualType ActualTy, 122 StoreManager &StoreMgr) { 123 // For now, the only adjustments we handle apply only to locations. 124 if (!V.getAs<Loc>()) 125 return V; 126 127 // If the types already match, don't do any unnecessary work. 128 ExpectedTy = ExpectedTy.getCanonicalType(); 129 ActualTy = ActualTy.getCanonicalType(); 130 if (ExpectedTy == ActualTy) 131 return V; 132 133 // No adjustment is needed between Objective-C pointer types. 134 if (ExpectedTy->isObjCObjectPointerType() && 135 ActualTy->isObjCObjectPointerType()) 136 return V; 137 138 // C++ object pointers may need "derived-to-base" casts. 139 const CXXRecordDecl *ExpectedClass = ExpectedTy->getPointeeCXXRecordDecl(); 140 const CXXRecordDecl *ActualClass = ActualTy->getPointeeCXXRecordDecl(); 141 if (ExpectedClass && ActualClass) { 142 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 143 /*DetectVirtual=*/false); 144 if (ActualClass->isDerivedFrom(ExpectedClass, Paths) && 145 !Paths.isAmbiguous(ActualTy->getCanonicalTypeUnqualified())) { 146 return StoreMgr.evalDerivedToBase(V, Paths.front()); 147 } 148 } 149 150 // Unfortunately, Objective-C does not enforce that overridden methods have 151 // covariant return types, so we can't assert that that never happens. 152 // Be safe and return UnknownVal(). 153 return UnknownVal(); 154} 155 156void ExprEngine::removeDeadOnEndOfFunction(NodeBuilderContext& BC, 157 ExplodedNode *Pred, 158 ExplodedNodeSet &Dst) { 159 // Find the last statement in the function and the corresponding basic block. 160 const Stmt *LastSt = 0; 161 const CFGBlock *Blk = 0; 162 llvm::tie(LastSt, Blk) = getLastStmt(Pred); 163 if (!Blk || !LastSt) { 164 Dst.Add(Pred); 165 return; 166 } 167 168 // Here, we destroy the current location context. We use the current 169 // function's entire body as a diagnostic statement, with which the program 170 // point will be associated. However, we only want to use LastStmt as a 171 // reference for what to clean up if it's a ReturnStmt; otherwise, everything 172 // is dead. 173 SaveAndRestore<const NodeBuilderContext *> NodeContextRAII(currBldrCtx, &BC); 174 const LocationContext *LCtx = Pred->getLocationContext(); 175 removeDead(Pred, Dst, dyn_cast<ReturnStmt>(LastSt), LCtx, 176 LCtx->getAnalysisDeclContext()->getBody(), 177 ProgramPoint::PostStmtPurgeDeadSymbolsKind); 178} 179 180static bool wasDifferentDeclUsedForInlining(CallEventRef<> Call, 181 const StackFrameContext *calleeCtx) { 182 const Decl *RuntimeCallee = calleeCtx->getDecl(); 183 const Decl *StaticDecl = Call->getDecl(); 184 assert(RuntimeCallee); 185 if (!StaticDecl) 186 return true; 187 return RuntimeCallee->getCanonicalDecl() != StaticDecl->getCanonicalDecl(); 188} 189 190/// Returns true if the CXXConstructExpr \p E was intended to construct a 191/// prvalue for the region in \p V. 192/// 193/// Note that we can't just test for rvalue vs. glvalue because 194/// CXXConstructExprs embedded in DeclStmts and initializers are considered 195/// rvalues by the AST, and the analyzer would like to treat them as lvalues. 196static bool isTemporaryPRValue(const CXXConstructExpr *E, SVal V) { 197 if (E->isGLValue()) 198 return false; 199 200 const MemRegion *MR = V.getAsRegion(); 201 if (!MR) 202 return false; 203 204 return isa<CXXTempObjectRegion>(MR); 205} 206 207/// The call exit is simulated with a sequence of nodes, which occur between 208/// CallExitBegin and CallExitEnd. The following operations occur between the 209/// two program points: 210/// 1. CallExitBegin (triggers the start of call exit sequence) 211/// 2. Bind the return value 212/// 3. Run Remove dead bindings to clean up the dead symbols from the callee. 213/// 4. CallExitEnd (switch to the caller context) 214/// 5. PostStmt<CallExpr> 215void ExprEngine::processCallExit(ExplodedNode *CEBNode) { 216 // Step 1 CEBNode was generated before the call. 217 218 const StackFrameContext *calleeCtx = 219 CEBNode->getLocationContext()->getCurrentStackFrame(); 220 221 // The parent context might not be a stack frame, so make sure we 222 // look up the first enclosing stack frame. 223 const StackFrameContext *callerCtx = 224 calleeCtx->getParent()->getCurrentStackFrame(); 225 226 const Stmt *CE = calleeCtx->getCallSite(); 227 ProgramStateRef state = CEBNode->getState(); 228 // Find the last statement in the function and the corresponding basic block. 229 const Stmt *LastSt = 0; 230 const CFGBlock *Blk = 0; 231 llvm::tie(LastSt, Blk) = getLastStmt(CEBNode); 232 233 // Generate a CallEvent /before/ cleaning the state, so that we can get the 234 // correct value for 'this' (if necessary). 235 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 236 CallEventRef<> Call = CEMgr.getCaller(calleeCtx, state); 237 238 // Step 2: generate node with bound return value: CEBNode -> BindedRetNode. 239 240 // If the callee returns an expression, bind its value to CallExpr. 241 if (CE) { 242 if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) { 243 const LocationContext *LCtx = CEBNode->getLocationContext(); 244 SVal V = state->getSVal(RS, LCtx); 245 246 // Ensure that the return type matches the type of the returned Expr. 247 if (wasDifferentDeclUsedForInlining(Call, calleeCtx)) { 248 QualType ReturnedTy = 249 CallEvent::getDeclaredResultType(calleeCtx->getDecl()); 250 if (!ReturnedTy.isNull()) { 251 if (const Expr *Ex = dyn_cast<Expr>(CE)) { 252 V = adjustReturnValue(V, Ex->getType(), ReturnedTy, 253 getStoreManager()); 254 } 255 } 256 } 257 258 state = state->BindExpr(CE, callerCtx, V); 259 } 260 261 // Bind the constructed object value to CXXConstructExpr. 262 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(CE)) { 263 loc::MemRegionVal This = 264 svalBuilder.getCXXThis(CCE->getConstructor()->getParent(), calleeCtx); 265 SVal ThisV = state->getSVal(This); 266 267 // If the constructed object is a temporary prvalue, get its bindings. 268 if (isTemporaryPRValue(CCE, ThisV)) 269 ThisV = state->getSVal(ThisV.castAs<Loc>()); 270 271 state = state->BindExpr(CCE, callerCtx, ThisV); 272 } 273 } 274 275 // Step 3: BindedRetNode -> CleanedNodes 276 // If we can find a statement and a block in the inlined function, run remove 277 // dead bindings before returning from the call. This is important to ensure 278 // that we report the issues such as leaks in the stack contexts in which 279 // they occurred. 280 ExplodedNodeSet CleanedNodes; 281 if (LastSt && Blk && AMgr.options.AnalysisPurgeOpt != PurgeNone) { 282 static SimpleProgramPointTag retValBind("ExprEngine : Bind Return Value"); 283 PostStmt Loc(LastSt, calleeCtx, &retValBind); 284 bool isNew; 285 ExplodedNode *BindedRetNode = G.getNode(Loc, state, false, &isNew); 286 BindedRetNode->addPredecessor(CEBNode, G); 287 if (!isNew) 288 return; 289 290 NodeBuilderContext Ctx(getCoreEngine(), Blk, BindedRetNode); 291 currBldrCtx = &Ctx; 292 // Here, we call the Symbol Reaper with 0 statement and callee location 293 // context, telling it to clean up everything in the callee's context 294 // (and its children). We use the callee's function body as a diagnostic 295 // statement, with which the program point will be associated. 296 removeDead(BindedRetNode, CleanedNodes, 0, calleeCtx, 297 calleeCtx->getAnalysisDeclContext()->getBody(), 298 ProgramPoint::PostStmtPurgeDeadSymbolsKind); 299 currBldrCtx = 0; 300 } else { 301 CleanedNodes.Add(CEBNode); 302 } 303 304 for (ExplodedNodeSet::iterator I = CleanedNodes.begin(), 305 E = CleanedNodes.end(); I != E; ++I) { 306 307 // Step 4: Generate the CallExit and leave the callee's context. 308 // CleanedNodes -> CEENode 309 CallExitEnd Loc(calleeCtx, callerCtx); 310 bool isNew; 311 ProgramStateRef CEEState = (*I == CEBNode) ? state : (*I)->getState(); 312 ExplodedNode *CEENode = G.getNode(Loc, CEEState, false, &isNew); 313 CEENode->addPredecessor(*I, G); 314 if (!isNew) 315 return; 316 317 // Step 5: Perform the post-condition check of the CallExpr and enqueue the 318 // result onto the work list. 319 // CEENode -> Dst -> WorkList 320 NodeBuilderContext Ctx(Engine, calleeCtx->getCallSiteBlock(), CEENode); 321 SaveAndRestore<const NodeBuilderContext*> NBCSave(currBldrCtx, 322 &Ctx); 323 SaveAndRestore<unsigned> CBISave(currStmtIdx, calleeCtx->getIndex()); 324 325 CallEventRef<> UpdatedCall = Call.cloneWithState(CEEState); 326 327 ExplodedNodeSet DstPostCall; 328 getCheckerManager().runCheckersForPostCall(DstPostCall, CEENode, 329 *UpdatedCall, *this, 330 /*WasInlined=*/true); 331 332 ExplodedNodeSet Dst; 333 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) { 334 getCheckerManager().runCheckersForPostObjCMessage(Dst, DstPostCall, *Msg, 335 *this, 336 /*WasInlined=*/true); 337 } else if (CE) { 338 getCheckerManager().runCheckersForPostStmt(Dst, DstPostCall, CE, 339 *this, /*WasInlined=*/true); 340 } else { 341 Dst.insert(DstPostCall); 342 } 343 344 // Enqueue the next element in the block. 345 for (ExplodedNodeSet::iterator PSI = Dst.begin(), PSE = Dst.end(); 346 PSI != PSE; ++PSI) { 347 Engine.getWorkList()->enqueue(*PSI, calleeCtx->getCallSiteBlock(), 348 calleeCtx->getIndex()+1); 349 } 350 } 351} 352 353void ExprEngine::examineStackFrames(const Decl *D, const LocationContext *LCtx, 354 bool &IsRecursive, unsigned &StackDepth) { 355 IsRecursive = false; 356 StackDepth = 0; 357 358 while (LCtx) { 359 if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LCtx)) { 360 const Decl *DI = SFC->getDecl(); 361 362 // Mark recursive (and mutually recursive) functions and always count 363 // them when measuring the stack depth. 364 if (DI == D) { 365 IsRecursive = true; 366 ++StackDepth; 367 LCtx = LCtx->getParent(); 368 continue; 369 } 370 371 // Do not count the small functions when determining the stack depth. 372 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(DI); 373 const CFG *CalleeCFG = CalleeADC->getCFG(); 374 if (CalleeCFG->getNumBlockIDs() > AMgr.options.getAlwaysInlineSize()) 375 ++StackDepth; 376 } 377 LCtx = LCtx->getParent(); 378 } 379 380} 381 382static bool IsInStdNamespace(const FunctionDecl *FD) { 383 const DeclContext *DC = FD->getEnclosingNamespaceContext(); 384 const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC); 385 if (!ND) 386 return false; 387 388 while (const DeclContext *Parent = ND->getParent()) { 389 if (!isa<NamespaceDecl>(Parent)) 390 break; 391 ND = cast<NamespaceDecl>(Parent); 392 } 393 394 return ND->getName() == "std"; 395} 396 397// The GDM component containing the dynamic dispatch bifurcation info. When 398// the exact type of the receiver is not known, we want to explore both paths - 399// one on which we do inline it and the other one on which we don't. This is 400// done to ensure we do not drop coverage. 401// This is the map from the receiver region to a bool, specifying either we 402// consider this region's information precise or not along the given path. 403namespace { 404 enum DynamicDispatchMode { 405 DynamicDispatchModeInlined = 1, 406 DynamicDispatchModeConservative 407 }; 408} 409REGISTER_TRAIT_WITH_PROGRAMSTATE(DynamicDispatchBifurcationMap, 410 CLANG_ENTO_PROGRAMSTATE_MAP(const MemRegion *, 411 unsigned)) 412 413bool ExprEngine::inlineCall(const CallEvent &Call, const Decl *D, 414 NodeBuilder &Bldr, ExplodedNode *Pred, 415 ProgramStateRef State) { 416 assert(D); 417 418 const LocationContext *CurLC = Pred->getLocationContext(); 419 const StackFrameContext *CallerSFC = CurLC->getCurrentStackFrame(); 420 const LocationContext *ParentOfCallee = CallerSFC; 421 if (Call.getKind() == CE_Block) { 422 const BlockDataRegion *BR = cast<BlockCall>(Call).getBlockRegion(); 423 assert(BR && "If we have the block definition we should have its region"); 424 AnalysisDeclContext *BlockCtx = AMgr.getAnalysisDeclContext(D); 425 ParentOfCallee = BlockCtx->getBlockInvocationContext(CallerSFC, 426 cast<BlockDecl>(D), 427 BR); 428 } 429 430 // This may be NULL, but that's fine. 431 const Expr *CallE = Call.getOriginExpr(); 432 433 // Construct a new stack frame for the callee. 434 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); 435 const StackFrameContext *CalleeSFC = 436 CalleeADC->getStackFrame(ParentOfCallee, CallE, 437 currBldrCtx->getBlock(), 438 currStmtIdx); 439 440 441 CallEnter Loc(CallE, CalleeSFC, CurLC); 442 443 // Construct a new state which contains the mapping from actual to 444 // formal arguments. 445 State = State->enterStackFrame(Call, CalleeSFC); 446 447 bool isNew; 448 if (ExplodedNode *N = G.getNode(Loc, State, false, &isNew)) { 449 N->addPredecessor(Pred, G); 450 if (isNew) 451 Engine.getWorkList()->enqueue(N); 452 } 453 454 // If we decided to inline the call, the successor has been manually 455 // added onto the work list so remove it from the node builder. 456 Bldr.takeNodes(Pred); 457 458 NumInlinedCalls++; 459 460 // Mark the decl as visited. 461 if (VisitedCallees) 462 VisitedCallees->insert(D); 463 464 return true; 465} 466 467static ProgramStateRef getInlineFailedState(ProgramStateRef State, 468 const Stmt *CallE) { 469 const void *ReplayState = State->get<ReplayWithoutInlining>(); 470 if (!ReplayState) 471 return 0; 472 473 assert(ReplayState == CallE && "Backtracked to the wrong call."); 474 (void)CallE; 475 476 return State->remove<ReplayWithoutInlining>(); 477} 478 479void ExprEngine::VisitCallExpr(const CallExpr *CE, ExplodedNode *Pred, 480 ExplodedNodeSet &dst) { 481 // Perform the previsit of the CallExpr. 482 ExplodedNodeSet dstPreVisit; 483 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, CE, *this); 484 485 // Get the call in its initial state. We use this as a template to perform 486 // all the checks. 487 CallEventManager &CEMgr = getStateManager().getCallEventManager(); 488 CallEventRef<> CallTemplate 489 = CEMgr.getSimpleCall(CE, Pred->getState(), Pred->getLocationContext()); 490 491 // Evaluate the function call. We try each of the checkers 492 // to see if the can evaluate the function call. 493 ExplodedNodeSet dstCallEvaluated; 494 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 495 I != E; ++I) { 496 evalCall(dstCallEvaluated, *I, *CallTemplate); 497 } 498 499 // Finally, perform the post-condition check of the CallExpr and store 500 // the created nodes in 'Dst'. 501 // Note that if the call was inlined, dstCallEvaluated will be empty. 502 // The post-CallExpr check will occur in processCallExit. 503 getCheckerManager().runCheckersForPostStmt(dst, dstCallEvaluated, CE, 504 *this); 505} 506 507void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred, 508 const CallEvent &Call) { 509 // WARNING: At this time, the state attached to 'Call' may be older than the 510 // state in 'Pred'. This is a minor optimization since CheckerManager will 511 // use an updated CallEvent instance when calling checkers, but if 'Call' is 512 // ever used directly in this function all callers should be updated to pass 513 // the most recent state. (It is probably not worth doing the work here since 514 // for some callers this will not be necessary.) 515 516 // Run any pre-call checks using the generic call interface. 517 ExplodedNodeSet dstPreVisit; 518 getCheckerManager().runCheckersForPreCall(dstPreVisit, Pred, Call, *this); 519 520 // Actually evaluate the function call. We try each of the checkers 521 // to see if the can evaluate the function call, and get a callback at 522 // defaultEvalCall if all of them fail. 523 ExplodedNodeSet dstCallEvaluated; 524 getCheckerManager().runCheckersForEvalCall(dstCallEvaluated, dstPreVisit, 525 Call, *this); 526 527 // Finally, run any post-call checks. 528 getCheckerManager().runCheckersForPostCall(Dst, dstCallEvaluated, 529 Call, *this); 530} 531 532ProgramStateRef ExprEngine::bindReturnValue(const CallEvent &Call, 533 const LocationContext *LCtx, 534 ProgramStateRef State) { 535 const Expr *E = Call.getOriginExpr(); 536 if (!E) 537 return State; 538 539 // Some method families have known return values. 540 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) { 541 switch (Msg->getMethodFamily()) { 542 default: 543 break; 544 case OMF_autorelease: 545 case OMF_retain: 546 case OMF_self: { 547 // These methods return their receivers. 548 return State->BindExpr(E, LCtx, Msg->getReceiverSVal()); 549 } 550 } 551 } else if (const CXXConstructorCall *C = dyn_cast<CXXConstructorCall>(&Call)){ 552 SVal ThisV = C->getCXXThisVal(); 553 554 // If the constructed object is a temporary prvalue, get its bindings. 555 if (isTemporaryPRValue(cast<CXXConstructExpr>(E), ThisV)) 556 ThisV = State->getSVal(ThisV.castAs<Loc>()); 557 558 return State->BindExpr(E, LCtx, ThisV); 559 } 560 561 // Conjure a symbol if the return value is unknown. 562 QualType ResultTy = Call.getResultType(); 563 SValBuilder &SVB = getSValBuilder(); 564 unsigned Count = currBldrCtx->blockCount(); 565 SVal R = SVB.conjureSymbolVal(0, E, LCtx, ResultTy, Count); 566 return State->BindExpr(E, LCtx, R); 567} 568 569// Conservatively evaluate call by invalidating regions and binding 570// a conjured return value. 571void ExprEngine::conservativeEvalCall(const CallEvent &Call, NodeBuilder &Bldr, 572 ExplodedNode *Pred, 573 ProgramStateRef State) { 574 State = Call.invalidateRegions(currBldrCtx->blockCount(), State); 575 State = bindReturnValue(Call, Pred->getLocationContext(), State); 576 577 // And make the result node. 578 Bldr.generateNode(Call.getProgramPoint(), State, Pred); 579} 580 581enum CallInlinePolicy { 582 CIP_Allowed, 583 CIP_DisallowedOnce, 584 CIP_DisallowedAlways 585}; 586 587static CallInlinePolicy mayInlineCallKind(const CallEvent &Call, 588 const ExplodedNode *Pred, 589 AnalyzerOptions &Opts) { 590 const LocationContext *CurLC = Pred->getLocationContext(); 591 const StackFrameContext *CallerSFC = CurLC->getCurrentStackFrame(); 592 switch (Call.getKind()) { 593 case CE_Function: 594 case CE_Block: 595 break; 596 case CE_CXXMember: 597 case CE_CXXMemberOperator: 598 if (!Opts.mayInlineCXXMemberFunction(CIMK_MemberFunctions)) 599 return CIP_DisallowedAlways; 600 break; 601 case CE_CXXConstructor: { 602 if (!Opts.mayInlineCXXMemberFunction(CIMK_Constructors)) 603 return CIP_DisallowedAlways; 604 605 const CXXConstructorCall &Ctor = cast<CXXConstructorCall>(Call); 606 607 // FIXME: We don't handle constructors or destructors for arrays properly. 608 // Even once we do, we still need to be careful about implicitly-generated 609 // initializers for array fields in default move/copy constructors. 610 const MemRegion *Target = Ctor.getCXXThisVal().getAsRegion(); 611 if (Target && isa<ElementRegion>(Target)) 612 return CIP_DisallowedOnce; 613 614 // FIXME: This is a hack. We don't use the correct region for a new 615 // expression, so if we inline the constructor its result will just be 616 // thrown away. This short-term hack is tracked in <rdar://problem/12180598> 617 // and the longer-term possible fix is discussed in PR12014. 618 const CXXConstructExpr *CtorExpr = Ctor.getOriginExpr(); 619 if (const Stmt *Parent = CurLC->getParentMap().getParent(CtorExpr)) 620 if (isa<CXXNewExpr>(Parent)) 621 return CIP_DisallowedOnce; 622 623 // Inlining constructors requires including initializers in the CFG. 624 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 625 assert(ADC->getCFGBuildOptions().AddInitializers && "No CFG initializers"); 626 (void)ADC; 627 628 // If the destructor is trivial, it's always safe to inline the constructor. 629 if (Ctor.getDecl()->getParent()->hasTrivialDestructor()) 630 break; 631 632 // For other types, only inline constructors if destructor inlining is 633 // also enabled. 634 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 635 return CIP_DisallowedAlways; 636 637 // FIXME: This is a hack. We don't handle temporary destructors 638 // right now, so we shouldn't inline their constructors. 639 if (CtorExpr->getConstructionKind() == CXXConstructExpr::CK_Complete) 640 if (!Target || !isa<DeclRegion>(Target)) 641 return CIP_DisallowedOnce; 642 643 break; 644 } 645 case CE_CXXDestructor: { 646 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors)) 647 return CIP_DisallowedAlways; 648 649 // Inlining destructors requires building the CFG correctly. 650 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); 651 assert(ADC->getCFGBuildOptions().AddImplicitDtors && "No CFG destructors"); 652 (void)ADC; 653 654 const CXXDestructorCall &Dtor = cast<CXXDestructorCall>(Call); 655 656 // FIXME: We don't handle constructors or destructors for arrays properly. 657 const MemRegion *Target = Dtor.getCXXThisVal().getAsRegion(); 658 if (Target && isa<ElementRegion>(Target)) 659 return CIP_DisallowedOnce; 660 661 break; 662 } 663 case CE_CXXAllocator: 664 // Do not inline allocators until we model deallocators. 665 // This is unfortunate, but basically necessary for smart pointers and such. 666 return CIP_DisallowedAlways; 667 case CE_ObjCMessage: 668 if (!Opts.mayInlineObjCMethod()) 669 return CIP_DisallowedAlways; 670 if (!(Opts.getIPAMode() == IPAK_DynamicDispatch || 671 Opts.getIPAMode() == IPAK_DynamicDispatchBifurcate)) 672 return CIP_DisallowedAlways; 673 break; 674 } 675 676 return CIP_Allowed; 677} 678 679/// Returns true if the given C++ class contains a member with the given name. 680static bool hasMember(const ASTContext &Ctx, const CXXRecordDecl *RD, 681 StringRef Name) { 682 const IdentifierInfo &II = Ctx.Idents.get(Name); 683 DeclarationName DeclName = Ctx.DeclarationNames.getIdentifier(&II); 684 if (!RD->lookup(DeclName).empty()) 685 return true; 686 687 CXXBasePaths Paths(false, false, false); 688 if (RD->lookupInBases(&CXXRecordDecl::FindOrdinaryMember, 689 DeclName.getAsOpaquePtr(), 690 Paths)) 691 return true; 692 693 return false; 694} 695 696/// Returns true if the given C++ class is a container or iterator. 697/// 698/// Our heuristic for this is whether it contains a method named 'begin()' or a 699/// nested type named 'iterator' or 'iterator_category'. 700static bool isContainerClass(const ASTContext &Ctx, const CXXRecordDecl *RD) { 701 return hasMember(Ctx, RD, "begin") || 702 hasMember(Ctx, RD, "iterator") || 703 hasMember(Ctx, RD, "iterator_category"); 704} 705 706/// Returns true if the given function refers to a constructor or destructor of 707/// a C++ container or iterator. 708/// 709/// We generally do a poor job modeling most containers right now, and would 710/// prefer not to inline their setup and teardown. 711static bool isContainerCtorOrDtor(const ASTContext &Ctx, 712 const FunctionDecl *FD) { 713 if (!(isa<CXXConstructorDecl>(FD) || isa<CXXDestructorDecl>(FD))) 714 return false; 715 716 const CXXRecordDecl *RD = cast<CXXMethodDecl>(FD)->getParent(); 717 return isContainerClass(Ctx, RD); 718} 719 720/// Returns true if the given function is the destructor of a class named 721/// "shared_ptr". 722static bool isCXXSharedPtrDtor(const FunctionDecl *FD) { 723 const CXXDestructorDecl *Dtor = dyn_cast<CXXDestructorDecl>(FD); 724 if (!Dtor) 725 return false; 726 727 const CXXRecordDecl *RD = Dtor->getParent(); 728 if (const IdentifierInfo *II = RD->getDeclName().getAsIdentifierInfo()) 729 if (II->isStr("shared_ptr")) 730 return true; 731 732 return false; 733} 734 735/// Returns true if the function in \p CalleeADC may be inlined in general. 736/// 737/// This checks static properties of the function, such as its signature and 738/// CFG, to determine whether the analyzer should ever consider inlining it, 739/// in any context. 740static bool mayInlineDecl(const CallEvent &Call, AnalysisDeclContext *CalleeADC, 741 AnalyzerOptions &Opts) { 742 // FIXME: Do not inline variadic calls. 743 if (Call.isVariadic()) 744 return false; 745 746 // Check certain C++-related inlining policies. 747 ASTContext &Ctx = CalleeADC->getASTContext(); 748 if (Ctx.getLangOpts().CPlusPlus) { 749 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CalleeADC->getDecl())) { 750 // Conditionally control the inlining of template functions. 751 if (!Opts.mayInlineTemplateFunctions()) 752 if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate) 753 return false; 754 755 // Conditionally control the inlining of C++ standard library functions. 756 if (!Opts.mayInlineCXXStandardLibrary()) 757 if (Ctx.getSourceManager().isInSystemHeader(FD->getLocation())) 758 if (IsInStdNamespace(FD)) 759 return false; 760 761 // Conditionally control the inlining of methods on objects that look 762 // like C++ containers. 763 if (!Opts.mayInlineCXXContainerCtorsAndDtors()) 764 if (!Ctx.getSourceManager().isFromMainFile(FD->getLocation())) 765 if (isContainerCtorOrDtor(Ctx, FD)) 766 return false; 767 768 // Conditionally control the inlining of the destructor of C++ shared_ptr. 769 // We don't currently do a good job modeling shared_ptr because we can't 770 // see the reference count, so treating as opaque is probably the best 771 // idea. 772 if (!Opts.mayInlineCXXSharedPtrDtor()) 773 if (isCXXSharedPtrDtor(FD)) 774 return false; 775 776 } 777 } 778 779 // It is possible that the CFG cannot be constructed. 780 // Be safe, and check if the CalleeCFG is valid. 781 const CFG *CalleeCFG = CalleeADC->getCFG(); 782 if (!CalleeCFG) 783 return false; 784 785 // Do not inline large functions. 786 if (CalleeCFG->getNumBlockIDs() > Opts.getMaxInlinableSize()) 787 return false; 788 789 // It is possible that the live variables analysis cannot be 790 // run. If so, bail out. 791 if (!CalleeADC->getAnalysis<RelaxedLiveVariables>()) 792 return false; 793 794 return true; 795} 796 797bool ExprEngine::shouldInlineCall(const CallEvent &Call, const Decl *D, 798 const ExplodedNode *Pred) { 799 if (!D) 800 return false; 801 802 AnalysisManager &AMgr = getAnalysisManager(); 803 AnalyzerOptions &Opts = AMgr.options; 804 AnalysisDeclContextManager &ADCMgr = AMgr.getAnalysisDeclContextManager(); 805 AnalysisDeclContext *CalleeADC = ADCMgr.getContext(D); 806 807 // Temporary object destructor processing is currently broken, so we never 808 // inline them. 809 // FIME: Remove this once temp destructors are working. 810 if ((*currBldrCtx->getBlock())[currStmtIdx].getAs<CFGTemporaryDtor>()) 811 return false; 812 813 // The auto-synthesized bodies are essential to inline as they are 814 // usually small and commonly used. Note: we should do this check early on to 815 // ensure we always inline these calls. 816 if (CalleeADC->isBodyAutosynthesized()) 817 return true; 818 819 if (!AMgr.shouldInlineCall()) 820 return false; 821 822 // Check if this function has been marked as non-inlinable. 823 Optional<bool> MayInline = Engine.FunctionSummaries->mayInline(D); 824 if (MayInline.hasValue()) { 825 if (!MayInline.getValue()) 826 return false; 827 828 } else { 829 // We haven't actually checked the static properties of this function yet. 830 // Do that now, and record our decision in the function summaries. 831 if (mayInlineDecl(Call, CalleeADC, Opts)) { 832 Engine.FunctionSummaries->markMayInline(D); 833 } else { 834 Engine.FunctionSummaries->markShouldNotInline(D); 835 return false; 836 } 837 } 838 839 // Check if we should inline a call based on its kind. 840 // FIXME: this checks both static and dynamic properties of the call, which 841 // means we're redoing a bit of work that could be cached in the function 842 // summary. 843 CallInlinePolicy CIP = mayInlineCallKind(Call, Pred, Opts); 844 if (CIP != CIP_Allowed) { 845 if (CIP == CIP_DisallowedAlways) { 846 assert(!MayInline.hasValue() || MayInline.getValue()); 847 Engine.FunctionSummaries->markShouldNotInline(D); 848 } 849 return false; 850 } 851 852 const CFG *CalleeCFG = CalleeADC->getCFG(); 853 854 // Do not inline if recursive or we've reached max stack frame count. 855 bool IsRecursive = false; 856 unsigned StackDepth = 0; 857 examineStackFrames(D, Pred->getLocationContext(), IsRecursive, StackDepth); 858 if ((StackDepth >= Opts.InlineMaxStackDepth) && 859 ((CalleeCFG->getNumBlockIDs() > Opts.getAlwaysInlineSize()) 860 || IsRecursive)) 861 return false; 862 863 // Do not inline large functions too many times. 864 if ((Engine.FunctionSummaries->getNumTimesInlined(D) > 865 Opts.getMaxTimesInlineLarge()) && 866 CalleeCFG->getNumBlockIDs() > 13) { 867 NumReachedInlineCountMax++; 868 return false; 869 } 870 871 if (HowToInline == Inline_Minimal && 872 (CalleeCFG->getNumBlockIDs() > Opts.getAlwaysInlineSize() 873 || IsRecursive)) 874 return false; 875 876 Engine.FunctionSummaries->bumpNumTimesInlined(D); 877 878 return true; 879} 880 881static bool isTrivialObjectAssignment(const CallEvent &Call) { 882 const CXXInstanceCall *ICall = dyn_cast<CXXInstanceCall>(&Call); 883 if (!ICall) 884 return false; 885 886 const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(ICall->getDecl()); 887 if (!MD) 888 return false; 889 if (!(MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())) 890 return false; 891 892 return MD->isTrivial(); 893} 894 895void ExprEngine::defaultEvalCall(NodeBuilder &Bldr, ExplodedNode *Pred, 896 const CallEvent &CallTemplate) { 897 // Make sure we have the most recent state attached to the call. 898 ProgramStateRef State = Pred->getState(); 899 CallEventRef<> Call = CallTemplate.cloneWithState(State); 900 901 // Special-case trivial assignment operators. 902 if (isTrivialObjectAssignment(*Call)) { 903 performTrivialCopy(Bldr, Pred, *Call); 904 return; 905 } 906 907 // Try to inline the call. 908 // The origin expression here is just used as a kind of checksum; 909 // this should still be safe even for CallEvents that don't come from exprs. 910 const Expr *E = Call->getOriginExpr(); 911 912 ProgramStateRef InlinedFailedState = getInlineFailedState(State, E); 913 if (InlinedFailedState) { 914 // If we already tried once and failed, make sure we don't retry later. 915 State = InlinedFailedState; 916 } else { 917 RuntimeDefinition RD = Call->getRuntimeDefinition(); 918 const Decl *D = RD.getDecl(); 919 if (shouldInlineCall(*Call, D, Pred)) { 920 if (RD.mayHaveOtherDefinitions()) { 921 AnalyzerOptions &Options = getAnalysisManager().options; 922 923 // Explore with and without inlining the call. 924 if (Options.getIPAMode() == IPAK_DynamicDispatchBifurcate) { 925 BifurcateCall(RD.getDispatchRegion(), *Call, D, Bldr, Pred); 926 return; 927 } 928 929 // Don't inline if we're not in any dynamic dispatch mode. 930 if (Options.getIPAMode() != IPAK_DynamicDispatch) { 931 conservativeEvalCall(*Call, Bldr, Pred, State); 932 return; 933 } 934 } 935 936 // We are not bifurcating and we do have a Decl, so just inline. 937 if (inlineCall(*Call, D, Bldr, Pred, State)) 938 return; 939 } 940 } 941 942 // If we can't inline it, handle the return value and invalidate the regions. 943 conservativeEvalCall(*Call, Bldr, Pred, State); 944} 945 946void ExprEngine::BifurcateCall(const MemRegion *BifurReg, 947 const CallEvent &Call, const Decl *D, 948 NodeBuilder &Bldr, ExplodedNode *Pred) { 949 assert(BifurReg); 950 BifurReg = BifurReg->StripCasts(); 951 952 // Check if we've performed the split already - note, we only want 953 // to split the path once per memory region. 954 ProgramStateRef State = Pred->getState(); 955 const unsigned *BState = 956 State->get<DynamicDispatchBifurcationMap>(BifurReg); 957 if (BState) { 958 // If we are on "inline path", keep inlining if possible. 959 if (*BState == DynamicDispatchModeInlined) 960 if (inlineCall(Call, D, Bldr, Pred, State)) 961 return; 962 // If inline failed, or we are on the path where we assume we 963 // don't have enough info about the receiver to inline, conjure the 964 // return value and invalidate the regions. 965 conservativeEvalCall(Call, Bldr, Pred, State); 966 return; 967 } 968 969 // If we got here, this is the first time we process a message to this 970 // region, so split the path. 971 ProgramStateRef IState = 972 State->set<DynamicDispatchBifurcationMap>(BifurReg, 973 DynamicDispatchModeInlined); 974 inlineCall(Call, D, Bldr, Pred, IState); 975 976 ProgramStateRef NoIState = 977 State->set<DynamicDispatchBifurcationMap>(BifurReg, 978 DynamicDispatchModeConservative); 979 conservativeEvalCall(Call, Bldr, Pred, NoIState); 980 981 NumOfDynamicDispatchPathSplits++; 982 return; 983} 984 985 986void ExprEngine::VisitReturnStmt(const ReturnStmt *RS, ExplodedNode *Pred, 987 ExplodedNodeSet &Dst) { 988 989 ExplodedNodeSet dstPreVisit; 990 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, RS, *this); 991 992 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 993 994 if (RS->getRetValue()) { 995 for (ExplodedNodeSet::iterator it = dstPreVisit.begin(), 996 ei = dstPreVisit.end(); it != ei; ++it) { 997 B.generateNode(RS, *it, (*it)->getState()); 998 } 999 } 1000} 1001