1 //=-- ExprEngineCallAndReturn.cpp - Support for call/return -----*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines ExprEngine's support for calls and returns.
11 //===----------------------------------------------------------------------===//
13 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
14 #include "PrettyStackTraceLocationContext.h"
15 #include "clang/AST/CXXInheritance.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/Analysis/Analyses/LiveVariables.h"
18 #include "clang/Analysis/ConstructionContext.h"
19 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
21 #include "llvm/ADT/SmallSet.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/Support/SaveAndRestore.h"
25 using namespace clang;
28 #define DEBUG_TYPE "ExprEngine"
30 STATISTIC(NumOfDynamicDispatchPathSplits,
31 "The # of times we split the path due to imprecise dynamic dispatch info");
33 STATISTIC(NumInlinedCalls,
34 "The # of times we inlined a call");
36 STATISTIC(NumReachedInlineCountMax,
37 "The # of times we reached inline count maximum");
39 void ExprEngine::processCallEnter(NodeBuilderContext& BC, CallEnter CE,
41 // Get the entry block in the CFG of the callee.
42 const StackFrameContext *calleeCtx = CE.getCalleeContext();
43 PrettyStackTraceLocationContext CrashInfo(calleeCtx);
44 const CFGBlock *Entry = CE.getEntry();
47 assert(Entry->empty());
48 assert(Entry->succ_size() == 1);
50 // Get the solitary successor.
51 const CFGBlock *Succ = *(Entry->succ_begin());
53 // Construct an edge representing the starting location in the callee.
54 BlockEdge Loc(Entry, Succ, calleeCtx);
56 ProgramStateRef state = Pred->getState();
58 // Construct a new node, notify checkers that analysis of the function has
59 // begun, and add the resultant nodes to the worklist.
61 ExplodedNode *Node = G.getNode(Loc, state, false, &isNew);
62 Node->addPredecessor(Pred, G);
64 ExplodedNodeSet DstBegin;
65 processBeginOfFunction(BC, Node, DstBegin, Loc);
66 Engine.enqueue(DstBegin);
70 // Find the last statement on the path to the exploded node and the
71 // corresponding Block.
72 static std::pair<const Stmt*,
73 const CFGBlock*> getLastStmt(const ExplodedNode *Node) {
74 const Stmt *S = nullptr;
75 const CFGBlock *Blk = nullptr;
76 const StackFrameContext *SF = Node->getStackFrame();
78 // Back up through the ExplodedGraph until we reach a statement node in this
81 const ProgramPoint &PP = Node->getLocation();
83 if (PP.getStackFrame() == SF) {
84 if (Optional<StmtPoint> SP = PP.getAs<StmtPoint>()) {
87 } else if (Optional<CallExitEnd> CEE = PP.getAs<CallExitEnd>()) {
88 S = CEE->getCalleeContext()->getCallSite();
92 // If there is no statement, this is an implicitly-generated call.
93 // We'll walk backwards over it and then continue the loop to find
94 // an actual statement.
95 Optional<CallEnter> CE;
97 Node = Node->getFirstPred();
98 CE = Node->getLocationAs<CallEnter>();
99 } while (!CE || CE->getCalleeContext() != CEE->getCalleeContext());
101 // Continue searching the graph.
102 } else if (Optional<BlockEdge> BE = PP.getAs<BlockEdge>()) {
105 } else if (Optional<CallEnter> CE = PP.getAs<CallEnter>()) {
106 // If we reached the CallEnter for this function, it has no statements.
107 if (CE->getCalleeContext() == SF)
111 if (Node->pred_empty())
112 return std::make_pair(nullptr, nullptr);
114 Node = *Node->pred_begin();
117 return std::make_pair(S, Blk);
120 /// Adjusts a return value when the called function's return type does not
121 /// match the caller's expression type. This can happen when a dynamic call
122 /// is devirtualized, and the overriding method has a covariant (more specific)
123 /// return type than the parent's method. For C++ objects, this means we need
124 /// to add base casts.
125 static SVal adjustReturnValue(SVal V, QualType ExpectedTy, QualType ActualTy,
126 StoreManager &StoreMgr) {
127 // For now, the only adjustments we handle apply only to locations.
131 // If the types already match, don't do any unnecessary work.
132 ExpectedTy = ExpectedTy.getCanonicalType();
133 ActualTy = ActualTy.getCanonicalType();
134 if (ExpectedTy == ActualTy)
137 // No adjustment is needed between Objective-C pointer types.
138 if (ExpectedTy->isObjCObjectPointerType() &&
139 ActualTy->isObjCObjectPointerType())
142 // C++ object pointers may need "derived-to-base" casts.
143 const CXXRecordDecl *ExpectedClass = ExpectedTy->getPointeeCXXRecordDecl();
144 const CXXRecordDecl *ActualClass = ActualTy->getPointeeCXXRecordDecl();
145 if (ExpectedClass && ActualClass) {
146 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
147 /*DetectVirtual=*/false);
148 if (ActualClass->isDerivedFrom(ExpectedClass, Paths) &&
149 !Paths.isAmbiguous(ActualTy->getCanonicalTypeUnqualified())) {
150 return StoreMgr.evalDerivedToBase(V, Paths.front());
154 // Unfortunately, Objective-C does not enforce that overridden methods have
155 // covariant return types, so we can't assert that that never happens.
156 // Be safe and return UnknownVal().
160 void ExprEngine::removeDeadOnEndOfFunction(NodeBuilderContext& BC,
162 ExplodedNodeSet &Dst) {
163 // Find the last statement in the function and the corresponding basic block.
164 const Stmt *LastSt = nullptr;
165 const CFGBlock *Blk = nullptr;
166 std::tie(LastSt, Blk) = getLastStmt(Pred);
167 if (!Blk || !LastSt) {
172 // Here, we destroy the current location context. We use the current
173 // function's entire body as a diagnostic statement, with which the program
174 // point will be associated. However, we only want to use LastStmt as a
175 // reference for what to clean up if it's a ReturnStmt; otherwise, everything
177 SaveAndRestore<const NodeBuilderContext *> NodeContextRAII(currBldrCtx, &BC);
178 const LocationContext *LCtx = Pred->getLocationContext();
179 removeDead(Pred, Dst, dyn_cast<ReturnStmt>(LastSt), LCtx,
180 LCtx->getAnalysisDeclContext()->getBody(),
181 ProgramPoint::PostStmtPurgeDeadSymbolsKind);
184 static bool wasDifferentDeclUsedForInlining(CallEventRef<> Call,
185 const StackFrameContext *calleeCtx) {
186 const Decl *RuntimeCallee = calleeCtx->getDecl();
187 const Decl *StaticDecl = Call->getDecl();
188 assert(RuntimeCallee);
191 return RuntimeCallee->getCanonicalDecl() != StaticDecl->getCanonicalDecl();
194 /// The call exit is simulated with a sequence of nodes, which occur between
195 /// CallExitBegin and CallExitEnd. The following operations occur between the
196 /// two program points:
197 /// 1. CallExitBegin (triggers the start of call exit sequence)
198 /// 2. Bind the return value
199 /// 3. Run Remove dead bindings to clean up the dead symbols from the callee.
200 /// 4. CallExitEnd (switch to the caller context)
201 /// 5. PostStmt<CallExpr>
202 void ExprEngine::processCallExit(ExplodedNode *CEBNode) {
203 // Step 1 CEBNode was generated before the call.
204 PrettyStackTraceLocationContext CrashInfo(CEBNode->getLocationContext());
205 const StackFrameContext *calleeCtx = CEBNode->getStackFrame();
207 // The parent context might not be a stack frame, so make sure we
208 // look up the first enclosing stack frame.
209 const StackFrameContext *callerCtx =
210 calleeCtx->getParent()->getStackFrame();
212 const Stmt *CE = calleeCtx->getCallSite();
213 ProgramStateRef state = CEBNode->getState();
214 // Find the last statement in the function and the corresponding basic block.
215 const Stmt *LastSt = nullptr;
216 const CFGBlock *Blk = nullptr;
217 std::tie(LastSt, Blk) = getLastStmt(CEBNode);
219 // Generate a CallEvent /before/ cleaning the state, so that we can get the
220 // correct value for 'this' (if necessary).
221 CallEventManager &CEMgr = getStateManager().getCallEventManager();
222 CallEventRef<> Call = CEMgr.getCaller(calleeCtx, state);
224 // Step 2: generate node with bound return value: CEBNode -> BindedRetNode.
226 // If the callee returns an expression, bind its value to CallExpr.
228 if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) {
229 const LocationContext *LCtx = CEBNode->getLocationContext();
230 SVal V = state->getSVal(RS, LCtx);
232 // Ensure that the return type matches the type of the returned Expr.
233 if (wasDifferentDeclUsedForInlining(Call, calleeCtx)) {
234 QualType ReturnedTy =
235 CallEvent::getDeclaredResultType(calleeCtx->getDecl());
236 if (!ReturnedTy.isNull()) {
237 if (const Expr *Ex = dyn_cast<Expr>(CE)) {
238 V = adjustReturnValue(V, Ex->getType(), ReturnedTy,
244 state = state->BindExpr(CE, callerCtx, V);
247 // Bind the constructed object value to CXXConstructExpr.
248 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(CE)) {
249 loc::MemRegionVal This =
250 svalBuilder.getCXXThis(CCE->getConstructor()->getParent(), calleeCtx);
251 SVal ThisV = state->getSVal(This);
252 ThisV = state->getSVal(ThisV.castAs<Loc>());
253 state = state->BindExpr(CCE, callerCtx, ThisV);
256 if (const auto *CNE = dyn_cast<CXXNewExpr>(CE)) {
257 // We are currently evaluating a CXXNewAllocator CFGElement. It takes a
258 // while to reach the actual CXXNewExpr element from here, so keep the
259 // region for later use.
260 // Additionally cast the return value of the inlined operator new
261 // (which is of type 'void *') to the correct object type.
262 SVal AllocV = state->getSVal(CNE, callerCtx);
263 AllocV = svalBuilder.evalCast(
264 AllocV, CNE->getType(),
265 getContext().getPointerType(getContext().VoidTy));
267 state = addObjectUnderConstruction(state, CNE, calleeCtx->getParent(),
272 // Step 3: BindedRetNode -> CleanedNodes
273 // If we can find a statement and a block in the inlined function, run remove
274 // dead bindings before returning from the call. This is important to ensure
275 // that we report the issues such as leaks in the stack contexts in which
277 ExplodedNodeSet CleanedNodes;
278 if (LastSt && Blk && AMgr.options.AnalysisPurgeOpt != PurgeNone) {
279 static SimpleProgramPointTag retValBind("ExprEngine", "Bind Return Value");
280 PostStmt Loc(LastSt, calleeCtx, &retValBind);
282 ExplodedNode *BindedRetNode = G.getNode(Loc, state, false, &isNew);
283 BindedRetNode->addPredecessor(CEBNode, G);
287 NodeBuilderContext Ctx(getCoreEngine(), Blk, BindedRetNode);
289 // Here, we call the Symbol Reaper with 0 statement and callee location
290 // context, telling it to clean up everything in the callee's context
291 // (and its children). We use the callee's function body as a diagnostic
292 // statement, with which the program point will be associated.
293 removeDead(BindedRetNode, CleanedNodes, nullptr, calleeCtx,
294 calleeCtx->getAnalysisDeclContext()->getBody(),
295 ProgramPoint::PostStmtPurgeDeadSymbolsKind);
296 currBldrCtx = nullptr;
298 CleanedNodes.Add(CEBNode);
301 for (ExplodedNodeSet::iterator I = CleanedNodes.begin(),
302 E = CleanedNodes.end(); I != E; ++I) {
304 // Step 4: Generate the CallExit and leave the callee's context.
305 // CleanedNodes -> CEENode
306 CallExitEnd Loc(calleeCtx, callerCtx);
308 ProgramStateRef CEEState = (*I == CEBNode) ? state : (*I)->getState();
310 ExplodedNode *CEENode = G.getNode(Loc, CEEState, false, &isNew);
311 CEENode->addPredecessor(*I, G);
315 // Step 5: Perform the post-condition check of the CallExpr and enqueue the
316 // result onto the work list.
317 // CEENode -> Dst -> WorkList
318 NodeBuilderContext Ctx(Engine, calleeCtx->getCallSiteBlock(), CEENode);
319 SaveAndRestore<const NodeBuilderContext*> NBCSave(currBldrCtx,
321 SaveAndRestore<unsigned> CBISave(currStmtIdx, calleeCtx->getIndex());
323 CallEventRef<> UpdatedCall = Call.cloneWithState(CEEState);
325 ExplodedNodeSet DstPostCall;
326 if (const CXXNewExpr *CNE = dyn_cast_or_null<CXXNewExpr>(CE)) {
327 ExplodedNodeSet DstPostPostCallCallback;
328 getCheckerManager().runCheckersForPostCall(DstPostPostCallCallback,
329 CEENode, *UpdatedCall, *this,
330 /*wasInlined=*/true);
331 for (auto I : DstPostPostCallCallback) {
332 getCheckerManager().runCheckersForNewAllocator(
334 *getObjectUnderConstruction(I->getState(), CNE,
335 calleeCtx->getParent()),
336 DstPostCall, I, *this,
337 /*wasInlined=*/true);
340 getCheckerManager().runCheckersForPostCall(DstPostCall, CEENode,
342 /*wasInlined=*/true);
345 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) {
346 getCheckerManager().runCheckersForPostObjCMessage(Dst, DstPostCall, *Msg,
348 /*wasInlined=*/true);
350 !(isa<CXXNewExpr>(CE) && // Called when visiting CXXNewExpr.
351 AMgr.getAnalyzerOptions().MayInlineCXXAllocator)) {
352 getCheckerManager().runCheckersForPostStmt(Dst, DstPostCall, CE,
353 *this, /*wasInlined=*/true);
355 Dst.insert(DstPostCall);
358 // Enqueue the next element in the block.
359 for (ExplodedNodeSet::iterator PSI = Dst.begin(), PSE = Dst.end();
361 Engine.getWorkList()->enqueue(*PSI, calleeCtx->getCallSiteBlock(),
362 calleeCtx->getIndex()+1);
367 bool ExprEngine::isSmall(AnalysisDeclContext *ADC) const {
368 // When there are no branches in the function, it means that there's no
369 // exponential complexity introduced by inlining such function.
370 // Such functions also don't trigger various fundamental problems
371 // with our inlining mechanism, such as the problem of
372 // inlined defensive checks. Hence isLinear().
373 const CFG *Cfg = ADC->getCFG();
374 return Cfg->isLinear() || Cfg->size() <= AMgr.options.AlwaysInlineSize;
377 bool ExprEngine::isLarge(AnalysisDeclContext *ADC) const {
378 const CFG *Cfg = ADC->getCFG();
379 return Cfg->size() >= AMgr.options.MinCFGSizeTreatFunctionsAsLarge;
382 bool ExprEngine::isHuge(AnalysisDeclContext *ADC) const {
383 const CFG *Cfg = ADC->getCFG();
384 return Cfg->getNumBlockIDs() > AMgr.options.MaxInlinableSize;
387 void ExprEngine::examineStackFrames(const Decl *D, const LocationContext *LCtx,
388 bool &IsRecursive, unsigned &StackDepth) {
393 if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LCtx)) {
394 const Decl *DI = SFC->getDecl();
396 // Mark recursive (and mutually recursive) functions and always count
397 // them when measuring the stack depth.
401 LCtx = LCtx->getParent();
405 // Do not count the small functions when determining the stack depth.
406 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(DI);
407 if (!isSmall(CalleeADC))
410 LCtx = LCtx->getParent();
414 // The GDM component containing the dynamic dispatch bifurcation info. When
415 // the exact type of the receiver is not known, we want to explore both paths -
416 // one on which we do inline it and the other one on which we don't. This is
417 // done to ensure we do not drop coverage.
418 // This is the map from the receiver region to a bool, specifying either we
419 // consider this region's information precise or not along the given path.
421 enum DynamicDispatchMode {
422 DynamicDispatchModeInlined = 1,
423 DynamicDispatchModeConservative
425 } // end anonymous namespace
427 REGISTER_MAP_WITH_PROGRAMSTATE(DynamicDispatchBifurcationMap,
428 const MemRegion *, unsigned)
430 bool ExprEngine::inlineCall(const CallEvent &Call, const Decl *D,
431 NodeBuilder &Bldr, ExplodedNode *Pred,
432 ProgramStateRef State) {
435 const LocationContext *CurLC = Pred->getLocationContext();
436 const StackFrameContext *CallerSFC = CurLC->getStackFrame();
437 const LocationContext *ParentOfCallee = CallerSFC;
438 if (Call.getKind() == CE_Block &&
439 !cast<BlockCall>(Call).isConversionFromLambda()) {
440 const BlockDataRegion *BR = cast<BlockCall>(Call).getBlockRegion();
441 assert(BR && "If we have the block definition we should have its region");
442 AnalysisDeclContext *BlockCtx = AMgr.getAnalysisDeclContext(D);
443 ParentOfCallee = BlockCtx->getBlockInvocationContext(CallerSFC,
448 // This may be NULL, but that's fine.
449 const Expr *CallE = Call.getOriginExpr();
451 // Construct a new stack frame for the callee.
452 AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D);
453 const StackFrameContext *CalleeSFC =
454 CalleeADC->getStackFrame(ParentOfCallee, CallE,
455 currBldrCtx->getBlock(),
458 CallEnter Loc(CallE, CalleeSFC, CurLC);
460 // Construct a new state which contains the mapping from actual to
462 State = State->enterStackFrame(Call, CalleeSFC);
465 if (ExplodedNode *N = G.getNode(Loc, State, false, &isNew)) {
466 N->addPredecessor(Pred, G);
468 Engine.getWorkList()->enqueue(N);
471 // If we decided to inline the call, the successor has been manually
472 // added onto the work list so remove it from the node builder.
473 Bldr.takeNodes(Pred);
476 Engine.FunctionSummaries->bumpNumTimesInlined(D);
478 // Mark the decl as visited.
480 VisitedCallees->insert(D);
485 static ProgramStateRef getInlineFailedState(ProgramStateRef State,
487 const void *ReplayState = State->get<ReplayWithoutInlining>();
491 assert(ReplayState == CallE && "Backtracked to the wrong call.");
494 return State->remove<ReplayWithoutInlining>();
497 void ExprEngine::VisitCallExpr(const CallExpr *CE, ExplodedNode *Pred,
498 ExplodedNodeSet &dst) {
499 // Perform the previsit of the CallExpr.
500 ExplodedNodeSet dstPreVisit;
501 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, CE, *this);
503 // Get the call in its initial state. We use this as a template to perform
505 CallEventManager &CEMgr = getStateManager().getCallEventManager();
506 CallEventRef<> CallTemplate
507 = CEMgr.getSimpleCall(CE, Pred->getState(), Pred->getLocationContext());
509 // Evaluate the function call. We try each of the checkers
510 // to see if the can evaluate the function call.
511 ExplodedNodeSet dstCallEvaluated;
512 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end();
514 evalCall(dstCallEvaluated, *I, *CallTemplate);
517 // Finally, perform the post-condition check of the CallExpr and store
518 // the created nodes in 'Dst'.
519 // Note that if the call was inlined, dstCallEvaluated will be empty.
520 // The post-CallExpr check will occur in processCallExit.
521 getCheckerManager().runCheckersForPostStmt(dst, dstCallEvaluated, CE,
525 ProgramStateRef ExprEngine::finishArgumentConstruction(ProgramStateRef State,
526 const CallEvent &Call) {
527 const Expr *E = Call.getOriginExpr();
528 // FIXME: Constructors to placement arguments of operator new
529 // are not supported yet.
530 if (!E || isa<CXXNewExpr>(E))
533 const LocationContext *LC = Call.getLocationContext();
534 for (unsigned CallI = 0, CallN = Call.getNumArgs(); CallI != CallN; ++CallI) {
535 unsigned I = Call.getASTArgumentIndex(CallI);
536 if (Optional<SVal> V =
537 getObjectUnderConstruction(State, {E, I}, LC)) {
540 assert(cast<VarRegion>(VV.castAs<loc::MemRegionVal>().getRegion())
541 ->getStackFrame()->getParent()
542 ->getStackFrame() == LC->getStackFrame());
543 State = finishObjectConstruction(State, {E, I}, LC);
550 void ExprEngine::finishArgumentConstruction(ExplodedNodeSet &Dst,
552 const CallEvent &Call) {
553 ProgramStateRef State = Pred->getState();
554 ProgramStateRef CleanedState = finishArgumentConstruction(State, Call);
555 if (CleanedState == State) {
560 const Expr *E = Call.getOriginExpr();
561 const LocationContext *LC = Call.getLocationContext();
562 NodeBuilder B(Pred, Dst, *currBldrCtx);
563 static SimpleProgramPointTag Tag("ExprEngine",
564 "Finish argument construction");
565 PreStmt PP(E, LC, &Tag);
566 B.generateNode(PP, CleanedState, Pred);
569 void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred,
570 const CallEvent &Call) {
571 // WARNING: At this time, the state attached to 'Call' may be older than the
572 // state in 'Pred'. This is a minor optimization since CheckerManager will
573 // use an updated CallEvent instance when calling checkers, but if 'Call' is
574 // ever used directly in this function all callers should be updated to pass
575 // the most recent state. (It is probably not worth doing the work here since
576 // for some callers this will not be necessary.)
578 // Run any pre-call checks using the generic call interface.
579 ExplodedNodeSet dstPreVisit;
580 getCheckerManager().runCheckersForPreCall(dstPreVisit, Pred,
583 // Actually evaluate the function call. We try each of the checkers
584 // to see if the can evaluate the function call, and get a callback at
585 // defaultEvalCall if all of them fail.
586 ExplodedNodeSet dstCallEvaluated;
587 getCheckerManager().runCheckersForEvalCall(dstCallEvaluated, dstPreVisit,
590 // If there were other constructors called for object-type arguments
591 // of this call, clean them up.
592 ExplodedNodeSet dstArgumentCleanup;
593 for (auto I : dstCallEvaluated)
594 finishArgumentConstruction(dstArgumentCleanup, I, Call);
596 // Finally, run any post-call checks.
597 getCheckerManager().runCheckersForPostCall(Dst, dstArgumentCleanup,
601 ProgramStateRef ExprEngine::bindReturnValue(const CallEvent &Call,
602 const LocationContext *LCtx,
603 ProgramStateRef State) {
604 const Expr *E = Call.getOriginExpr();
608 // Some method families have known return values.
609 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) {
610 switch (Msg->getMethodFamily()) {
613 case OMF_autorelease:
616 // These methods return their receivers.
617 return State->BindExpr(E, LCtx, Msg->getReceiverSVal());
620 } else if (const CXXConstructorCall *C = dyn_cast<CXXConstructorCall>(&Call)){
621 SVal ThisV = C->getCXXThisVal();
622 ThisV = State->getSVal(ThisV.castAs<Loc>());
623 return State->BindExpr(E, LCtx, ThisV);
627 QualType ResultTy = Call.getResultType();
628 unsigned Count = currBldrCtx->blockCount();
629 if (auto RTC = getCurrentCFGElement().getAs<CFGCXXRecordTypedCall>()) {
630 // Conjure a temporary if the function returns an object by value.
632 assert(RTC->getStmt() == Call.getOriginExpr());
633 EvalCallOptions CallOpts; // FIXME: We won't really need those.
634 std::tie(State, Target) =
635 prepareForObjectConstruction(Call.getOriginExpr(), State, LCtx,
636 RTC->getConstructionContext(), CallOpts);
637 const MemRegion *TargetR = Target.getAsRegion();
639 // Invalidate the region so that it didn't look uninitialized. If this is
640 // a field or element constructor, we do not want to invalidate
641 // the whole structure. Pointer escape is meaningless because
642 // the structure is a product of conservative evaluation
643 // and therefore contains nothing interesting at this point.
644 RegionAndSymbolInvalidationTraits ITraits;
645 ITraits.setTrait(TargetR,
646 RegionAndSymbolInvalidationTraits::TK_DoNotInvalidateSuperRegion);
647 State = State->invalidateRegions(TargetR, E, Count, LCtx,
648 /* CausesPointerEscape=*/false, nullptr,
651 R = State->getSVal(Target.castAs<Loc>(), E->getType());
653 // Conjure a symbol if the return value is unknown.
655 // See if we need to conjure a heap pointer instead of
656 // a regular unknown pointer.
657 bool IsHeapPointer = false;
658 if (const auto *CNE = dyn_cast<CXXNewExpr>(E))
659 if (CNE->getOperatorNew()->isReplaceableGlobalAllocationFunction()) {
660 // FIXME: Delegate this to evalCall in MallocChecker?
661 IsHeapPointer = true;
664 R = IsHeapPointer ? svalBuilder.getConjuredHeapSymbolVal(E, LCtx, Count)
665 : svalBuilder.conjureSymbolVal(nullptr, E, LCtx, ResultTy,
668 return State->BindExpr(E, LCtx, R);
671 // Conservatively evaluate call by invalidating regions and binding
672 // a conjured return value.
673 void ExprEngine::conservativeEvalCall(const CallEvent &Call, NodeBuilder &Bldr,
675 ProgramStateRef State) {
676 State = Call.invalidateRegions(currBldrCtx->blockCount(), State);
677 State = bindReturnValue(Call, Pred->getLocationContext(), State);
679 // And make the result node.
680 Bldr.generateNode(Call.getProgramPoint(), State, Pred);
683 ExprEngine::CallInlinePolicy
684 ExprEngine::mayInlineCallKind(const CallEvent &Call, const ExplodedNode *Pred,
685 AnalyzerOptions &Opts,
686 const ExprEngine::EvalCallOptions &CallOpts) {
687 const LocationContext *CurLC = Pred->getLocationContext();
688 const StackFrameContext *CallerSFC = CurLC->getStackFrame();
689 switch (Call.getKind()) {
694 case CE_CXXMemberOperator:
695 if (!Opts.mayInlineCXXMemberFunction(CIMK_MemberFunctions))
696 return CIP_DisallowedAlways;
698 case CE_CXXConstructor: {
699 if (!Opts.mayInlineCXXMemberFunction(CIMK_Constructors))
700 return CIP_DisallowedAlways;
702 const CXXConstructorCall &Ctor = cast<CXXConstructorCall>(Call);
704 const CXXConstructExpr *CtorExpr = Ctor.getOriginExpr();
706 auto CCE = getCurrentCFGElement().getAs<CFGConstructor>();
707 const ConstructionContext *CC = CCE ? CCE->getConstructionContext()
710 if (CC && isa<NewAllocatedObjectConstructionContext>(CC) &&
711 !Opts.MayInlineCXXAllocator)
712 return CIP_DisallowedOnce;
714 // FIXME: We don't handle constructors or destructors for arrays properly.
715 // Even once we do, we still need to be careful about implicitly-generated
716 // initializers for array fields in default move/copy constructors.
717 // We still allow construction into ElementRegion targets when they don't
718 // represent array elements.
719 if (CallOpts.IsArrayCtorOrDtor)
720 return CIP_DisallowedOnce;
722 // Inlining constructors requires including initializers in the CFG.
723 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext();
724 assert(ADC->getCFGBuildOptions().AddInitializers && "No CFG initializers");
727 // If the destructor is trivial, it's always safe to inline the constructor.
728 if (Ctor.getDecl()->getParent()->hasTrivialDestructor())
731 // For other types, only inline constructors if destructor inlining is
733 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors))
734 return CIP_DisallowedAlways;
736 if (CtorExpr->getConstructionKind() == CXXConstructExpr::CK_Complete) {
737 // If we don't handle temporary destructors, we shouldn't inline
738 // their constructors.
739 if (CallOpts.IsTemporaryCtorOrDtor &&
740 !Opts.ShouldIncludeTemporaryDtorsInCFG)
741 return CIP_DisallowedOnce;
743 // If we did not find the correct this-region, it would be pointless
744 // to inline the constructor. Instead we will simply invalidate
745 // the fake temporary target.
746 if (CallOpts.IsCtorOrDtorWithImproperlyModeledTargetRegion)
747 return CIP_DisallowedOnce;
749 // If the temporary is lifetime-extended by binding it to a reference-type
750 // field within an aggregate, automatic destructors don't work properly.
751 if (CallOpts.IsTemporaryLifetimeExtendedViaAggregate)
752 return CIP_DisallowedOnce;
757 case CE_CXXDestructor: {
758 if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors))
759 return CIP_DisallowedAlways;
761 // Inlining destructors requires building the CFG correctly.
762 const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext();
763 assert(ADC->getCFGBuildOptions().AddImplicitDtors && "No CFG destructors");
766 // FIXME: We don't handle constructors or destructors for arrays properly.
767 if (CallOpts.IsArrayCtorOrDtor)
768 return CIP_DisallowedOnce;
770 // Allow disabling temporary destructor inlining with a separate option.
771 if (CallOpts.IsTemporaryCtorOrDtor &&
772 !Opts.MayInlineCXXTemporaryDtors)
773 return CIP_DisallowedOnce;
775 // If we did not find the correct this-region, it would be pointless
776 // to inline the destructor. Instead we will simply invalidate
777 // the fake temporary target.
778 if (CallOpts.IsCtorOrDtorWithImproperlyModeledTargetRegion)
779 return CIP_DisallowedOnce;
782 case CE_CXXAllocator:
783 if (Opts.MayInlineCXXAllocator)
785 // Do not inline allocators until we model deallocators.
786 // This is unfortunate, but basically necessary for smart pointers and such.
787 return CIP_DisallowedAlways;
789 if (!Opts.MayInlineObjCMethod)
790 return CIP_DisallowedAlways;
791 if (!(Opts.getIPAMode() == IPAK_DynamicDispatch ||
792 Opts.getIPAMode() == IPAK_DynamicDispatchBifurcate))
793 return CIP_DisallowedAlways;
800 /// Returns true if the given C++ class contains a member with the given name.
801 static bool hasMember(const ASTContext &Ctx, const CXXRecordDecl *RD,
803 const IdentifierInfo &II = Ctx.Idents.get(Name);
804 DeclarationName DeclName = Ctx.DeclarationNames.getIdentifier(&II);
805 if (!RD->lookup(DeclName).empty())
808 CXXBasePaths Paths(false, false, false);
809 if (RD->lookupInBases(
810 [DeclName](const CXXBaseSpecifier *Specifier, CXXBasePath &Path) {
811 return CXXRecordDecl::FindOrdinaryMember(Specifier, Path, DeclName);
819 /// Returns true if the given C++ class is a container or iterator.
821 /// Our heuristic for this is whether it contains a method named 'begin()' or a
822 /// nested type named 'iterator' or 'iterator_category'.
823 static bool isContainerClass(const ASTContext &Ctx, const CXXRecordDecl *RD) {
824 return hasMember(Ctx, RD, "begin") ||
825 hasMember(Ctx, RD, "iterator") ||
826 hasMember(Ctx, RD, "iterator_category");
829 /// Returns true if the given function refers to a method of a C++ container
832 /// We generally do a poor job modeling most containers right now, and might
833 /// prefer not to inline their methods.
834 static bool isContainerMethod(const ASTContext &Ctx,
835 const FunctionDecl *FD) {
836 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
837 return isContainerClass(Ctx, MD->getParent());
841 /// Returns true if the given function is the destructor of a class named
843 static bool isCXXSharedPtrDtor(const FunctionDecl *FD) {
844 const CXXDestructorDecl *Dtor = dyn_cast<CXXDestructorDecl>(FD);
848 const CXXRecordDecl *RD = Dtor->getParent();
849 if (const IdentifierInfo *II = RD->getDeclName().getAsIdentifierInfo())
850 if (II->isStr("shared_ptr"))
856 /// Returns true if the function in \p CalleeADC may be inlined in general.
858 /// This checks static properties of the function, such as its signature and
859 /// CFG, to determine whether the analyzer should ever consider inlining it,
861 bool ExprEngine::mayInlineDecl(AnalysisDeclContext *CalleeADC) const {
862 AnalyzerOptions &Opts = AMgr.getAnalyzerOptions();
863 // FIXME: Do not inline variadic calls.
864 if (CallEvent::isVariadic(CalleeADC->getDecl()))
867 // Check certain C++-related inlining policies.
868 ASTContext &Ctx = CalleeADC->getASTContext();
869 if (Ctx.getLangOpts().CPlusPlus) {
870 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CalleeADC->getDecl())) {
871 // Conditionally control the inlining of template functions.
872 if (!Opts.MayInlineTemplateFunctions)
873 if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate)
876 // Conditionally control the inlining of C++ standard library functions.
877 if (!Opts.MayInlineCXXStandardLibrary)
878 if (Ctx.getSourceManager().isInSystemHeader(FD->getLocation()))
879 if (AnalysisDeclContext::isInStdNamespace(FD))
882 // Conditionally control the inlining of methods on objects that look
883 // like C++ containers.
884 if (!Opts.MayInlineCXXContainerMethods)
885 if (!AMgr.isInCodeFile(FD->getLocation()))
886 if (isContainerMethod(Ctx, FD))
889 // Conditionally control the inlining of the destructor of C++ shared_ptr.
890 // We don't currently do a good job modeling shared_ptr because we can't
891 // see the reference count, so treating as opaque is probably the best
893 if (!Opts.MayInlineCXXSharedPtrDtor)
894 if (isCXXSharedPtrDtor(FD))
899 // It is possible that the CFG cannot be constructed.
900 // Be safe, and check if the CalleeCFG is valid.
901 const CFG *CalleeCFG = CalleeADC->getCFG();
905 // Do not inline large functions.
906 if (isHuge(CalleeADC))
909 // It is possible that the live variables analysis cannot be
910 // run. If so, bail out.
911 if (!CalleeADC->getAnalysis<RelaxedLiveVariables>())
917 bool ExprEngine::shouldInlineCall(const CallEvent &Call, const Decl *D,
918 const ExplodedNode *Pred,
919 const EvalCallOptions &CallOpts) {
923 AnalysisManager &AMgr = getAnalysisManager();
924 AnalyzerOptions &Opts = AMgr.options;
925 AnalysisDeclContextManager &ADCMgr = AMgr.getAnalysisDeclContextManager();
926 AnalysisDeclContext *CalleeADC = ADCMgr.getContext(D);
928 // The auto-synthesized bodies are essential to inline as they are
929 // usually small and commonly used. Note: we should do this check early on to
930 // ensure we always inline these calls.
931 if (CalleeADC->isBodyAutosynthesized())
934 if (!AMgr.shouldInlineCall())
937 // Check if this function has been marked as non-inlinable.
938 Optional<bool> MayInline = Engine.FunctionSummaries->mayInline(D);
939 if (MayInline.hasValue()) {
940 if (!MayInline.getValue())
944 // We haven't actually checked the static properties of this function yet.
945 // Do that now, and record our decision in the function summaries.
946 if (mayInlineDecl(CalleeADC)) {
947 Engine.FunctionSummaries->markMayInline(D);
949 Engine.FunctionSummaries->markShouldNotInline(D);
954 // Check if we should inline a call based on its kind.
955 // FIXME: this checks both static and dynamic properties of the call, which
956 // means we're redoing a bit of work that could be cached in the function
958 CallInlinePolicy CIP = mayInlineCallKind(Call, Pred, Opts, CallOpts);
959 if (CIP != CIP_Allowed) {
960 if (CIP == CIP_DisallowedAlways) {
961 assert(!MayInline.hasValue() || MayInline.getValue());
962 Engine.FunctionSummaries->markShouldNotInline(D);
967 // Do not inline if recursive or we've reached max stack frame count.
968 bool IsRecursive = false;
969 unsigned StackDepth = 0;
970 examineStackFrames(D, Pred->getLocationContext(), IsRecursive, StackDepth);
971 if ((StackDepth >= Opts.InlineMaxStackDepth) &&
972 (!isSmall(CalleeADC) || IsRecursive))
975 // Do not inline large functions too many times.
976 if ((Engine.FunctionSummaries->getNumTimesInlined(D) >
977 Opts.MaxTimesInlineLarge) &&
978 isLarge(CalleeADC)) {
979 NumReachedInlineCountMax++;
983 if (HowToInline == Inline_Minimal && (!isSmall(CalleeADC) || IsRecursive))
989 static bool isTrivialObjectAssignment(const CallEvent &Call) {
990 const CXXInstanceCall *ICall = dyn_cast<CXXInstanceCall>(&Call);
994 const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(ICall->getDecl());
997 if (!(MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()))
1000 return MD->isTrivial();
1003 void ExprEngine::defaultEvalCall(NodeBuilder &Bldr, ExplodedNode *Pred,
1004 const CallEvent &CallTemplate,
1005 const EvalCallOptions &CallOpts) {
1006 // Make sure we have the most recent state attached to the call.
1007 ProgramStateRef State = Pred->getState();
1008 CallEventRef<> Call = CallTemplate.cloneWithState(State);
1010 // Special-case trivial assignment operators.
1011 if (isTrivialObjectAssignment(*Call)) {
1012 performTrivialCopy(Bldr, Pred, *Call);
1016 // Try to inline the call.
1017 // The origin expression here is just used as a kind of checksum;
1018 // this should still be safe even for CallEvents that don't come from exprs.
1019 const Expr *E = Call->getOriginExpr();
1021 ProgramStateRef InlinedFailedState = getInlineFailedState(State, E);
1022 if (InlinedFailedState) {
1023 // If we already tried once and failed, make sure we don't retry later.
1024 State = InlinedFailedState;
1026 RuntimeDefinition RD = Call->getRuntimeDefinition();
1027 const Decl *D = RD.getDecl();
1028 if (shouldInlineCall(*Call, D, Pred, CallOpts)) {
1029 if (RD.mayHaveOtherDefinitions()) {
1030 AnalyzerOptions &Options = getAnalysisManager().options;
1032 // Explore with and without inlining the call.
1033 if (Options.getIPAMode() == IPAK_DynamicDispatchBifurcate) {
1034 BifurcateCall(RD.getDispatchRegion(), *Call, D, Bldr, Pred);
1038 // Don't inline if we're not in any dynamic dispatch mode.
1039 if (Options.getIPAMode() != IPAK_DynamicDispatch) {
1040 conservativeEvalCall(*Call, Bldr, Pred, State);
1045 // We are not bifurcating and we do have a Decl, so just inline.
1046 if (inlineCall(*Call, D, Bldr, Pred, State))
1051 // If we can't inline it, handle the return value and invalidate the regions.
1052 conservativeEvalCall(*Call, Bldr, Pred, State);
1055 void ExprEngine::BifurcateCall(const MemRegion *BifurReg,
1056 const CallEvent &Call, const Decl *D,
1057 NodeBuilder &Bldr, ExplodedNode *Pred) {
1059 BifurReg = BifurReg->StripCasts();
1061 // Check if we've performed the split already - note, we only want
1062 // to split the path once per memory region.
1063 ProgramStateRef State = Pred->getState();
1064 const unsigned *BState =
1065 State->get<DynamicDispatchBifurcationMap>(BifurReg);
1067 // If we are on "inline path", keep inlining if possible.
1068 if (*BState == DynamicDispatchModeInlined)
1069 if (inlineCall(Call, D, Bldr, Pred, State))
1071 // If inline failed, or we are on the path where we assume we
1072 // don't have enough info about the receiver to inline, conjure the
1073 // return value and invalidate the regions.
1074 conservativeEvalCall(Call, Bldr, Pred, State);
1078 // If we got here, this is the first time we process a message to this
1079 // region, so split the path.
1080 ProgramStateRef IState =
1081 State->set<DynamicDispatchBifurcationMap>(BifurReg,
1082 DynamicDispatchModeInlined);
1083 inlineCall(Call, D, Bldr, Pred, IState);
1085 ProgramStateRef NoIState =
1086 State->set<DynamicDispatchBifurcationMap>(BifurReg,
1087 DynamicDispatchModeConservative);
1088 conservativeEvalCall(Call, Bldr, Pred, NoIState);
1090 NumOfDynamicDispatchPathSplits++;
1093 void ExprEngine::VisitReturnStmt(const ReturnStmt *RS, ExplodedNode *Pred,
1094 ExplodedNodeSet &Dst) {
1095 ExplodedNodeSet dstPreVisit;
1096 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, RS, *this);
1098 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx);
1100 if (RS->getRetValue()) {
1101 for (ExplodedNodeSet::iterator it = dstPreVisit.begin(),
1102 ei = dstPreVisit.end(); it != ei; ++it) {
1103 B.generateNode(RS, *it, (*it)->getState());