| //=-- ExprEngineCallAndReturn.cpp - Support for call/return -----*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines ExprEngine's support for calls and returns. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Analysis/Analyses/LiveVariables.h" |
| #include "clang/StaticAnalyzer/Core/CheckerManager.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/Calls.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/Support/SaveAndRestore.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| static CallEventKind classifyCallExpr(const CallExpr *CE) { |
| if (isa<CXXMemberCallExpr>(CE)) |
| return CE_CXXMember; |
| |
| const CXXOperatorCallExpr *OpCE = dyn_cast<CXXOperatorCallExpr>(CE); |
| if (OpCE) { |
| const FunctionDecl *DirectCallee = CE->getDirectCallee(); |
| if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(DirectCallee)) |
| if (MD->isInstance()) |
| return CE_CXXMemberOperator; |
| } else if (CE->getCallee()->getType()->isBlockPointerType()) { |
| return CE_Block; |
| } |
| |
| return CE_Function; |
| } |
| |
| void ExprEngine::processCallEnter(CallEnter CE, ExplodedNode *Pred) { |
| // Get the entry block in the CFG of the callee. |
| const StackFrameContext *calleeCtx = CE.getCalleeContext(); |
| const CFG *CalleeCFG = calleeCtx->getCFG(); |
| const CFGBlock *Entry = &(CalleeCFG->getEntry()); |
| |
| // Validate the CFG. |
| assert(Entry->empty()); |
| assert(Entry->succ_size() == 1); |
| |
| // Get the solitary sucessor. |
| const CFGBlock *Succ = *(Entry->succ_begin()); |
| |
| // Construct an edge representing the starting location in the callee. |
| BlockEdge Loc(Entry, Succ, calleeCtx); |
| |
| ProgramStateRef state = Pred->getState(); |
| |
| // Construct a new node and add it to the worklist. |
| bool isNew; |
| ExplodedNode *Node = G.getNode(Loc, state, false, &isNew); |
| Node->addPredecessor(Pred, G); |
| if (isNew) |
| Engine.getWorkList()->enqueue(Node); |
| } |
| |
| // Find the last statement on the path to the exploded node and the |
| // corresponding Block. |
| static std::pair<const Stmt*, |
| const CFGBlock*> getLastStmt(const ExplodedNode *Node) { |
| const Stmt *S = 0; |
| const CFGBlock *Blk = 0; |
| const StackFrameContext *SF = |
| Node->getLocation().getLocationContext()->getCurrentStackFrame(); |
| while (Node) { |
| const ProgramPoint &PP = Node->getLocation(); |
| // Skip any BlockEdges, empty blocks, and the CallExitBegin node. |
| if (isa<BlockEdge>(PP) || isa<CallExitBegin>(PP) || isa<BlockEntrance>(PP)){ |
| assert(Node->pred_size() == 1); |
| Node = *Node->pred_begin(); |
| continue; |
| } |
| // If we reached the CallEnter, the function has no statements. |
| if (isa<CallEnter>(PP)) |
| break; |
| if (const StmtPoint *SP = dyn_cast<StmtPoint>(&PP)) { |
| S = SP->getStmt(); |
| // Now, get the enclosing basic block. |
| while (Node && Node->pred_size() >=1 ) { |
| const ProgramPoint &PP = Node->getLocation(); |
| if (isa<BlockEdge>(PP) && |
| (PP.getLocationContext()->getCurrentStackFrame() == SF)) { |
| BlockEdge &EPP = cast<BlockEdge>(PP); |
| Blk = EPP.getDst(); |
| break; |
| } |
| Node = *Node->pred_begin(); |
| } |
| break; |
| } |
| break; |
| } |
| return std::pair<const Stmt*, const CFGBlock*>(S, Blk); |
| } |
| |
| /// The call exit is simulated with a sequence of nodes, which occur between |
| /// CallExitBegin and CallExitEnd. The following operations occur between the |
| /// two program points: |
| /// 1. CallExitBegin (triggers the start of call exit sequence) |
| /// 2. Bind the return value |
| /// 3. Run Remove dead bindings to clean up the dead symbols from the callee. |
| /// 4. CallExitEnd (switch to the caller context) |
| /// 5. PostStmt<CallExpr> |
| void ExprEngine::processCallExit(ExplodedNode *CEBNode) { |
| // Step 1 CEBNode was generated before the call. |
| |
| const StackFrameContext *calleeCtx = |
| CEBNode->getLocationContext()->getCurrentStackFrame(); |
| |
| // The parent context might not be a stack frame, so make sure we |
| // look up the first enclosing stack frame. |
| const StackFrameContext *callerCtx = |
| calleeCtx->getParent()->getCurrentStackFrame(); |
| |
| const Stmt *CE = calleeCtx->getCallSite(); |
| ProgramStateRef state = CEBNode->getState(); |
| // Find the last statement in the function and the corresponding basic block. |
| const Stmt *LastSt = 0; |
| const CFGBlock *Blk = 0; |
| llvm::tie(LastSt, Blk) = getLastStmt(CEBNode); |
| |
| // Step 2: generate node with bound return value: CEBNode -> BindedRetNode. |
| |
| // If the callee returns an expression, bind its value to CallExpr. |
| if (CE) { |
| if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) { |
| const LocationContext *LCtx = CEBNode->getLocationContext(); |
| SVal V = state->getSVal(RS, LCtx); |
| state = state->BindExpr(CE, calleeCtx->getParent(), V); |
| } |
| |
| // Bind the constructed object value to CXXConstructExpr. |
| if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(CE)) { |
| loc::MemRegionVal This = |
| svalBuilder.getCXXThis(CCE->getConstructor()->getParent(), calleeCtx); |
| SVal ThisV = state->getSVal(This); |
| |
| // Always bind the region to the CXXConstructExpr. |
| state = state->BindExpr(CCE, calleeCtx->getParent(), ThisV); |
| } |
| } |
| |
| // Step 3: BindedRetNode -> CleanedNodes |
| // If we can find a statement and a block in the inlined function, run remove |
| // dead bindings before returning from the call. This is important to ensure |
| // that we report the issues such as leaks in the stack contexts in which |
| // they occurred. |
| ExplodedNodeSet CleanedNodes; |
| if (LastSt && Blk) { |
| static SimpleProgramPointTag retValBind("ExprEngine : Bind Return Value"); |
| PostStmt Loc(LastSt, calleeCtx, &retValBind); |
| bool isNew; |
| ExplodedNode *BindedRetNode = G.getNode(Loc, state, false, &isNew); |
| BindedRetNode->addPredecessor(CEBNode, G); |
| if (!isNew) |
| return; |
| |
| NodeBuilderContext Ctx(getCoreEngine(), Blk, BindedRetNode); |
| currentBuilderContext = &Ctx; |
| // Here, we call the Symbol Reaper with 0 statement and caller location |
| // context, telling it to clean up everything in the callee's context |
| // (and it's children). We use LastStmt as a diagnostic statement, which |
| // which the PreStmtPurge Dead point will be associated. |
| removeDead(BindedRetNode, CleanedNodes, 0, callerCtx, LastSt, |
| ProgramPoint::PostStmtPurgeDeadSymbolsKind); |
| currentBuilderContext = 0; |
| } else { |
| CleanedNodes.Add(CEBNode); |
| } |
| |
| for (ExplodedNodeSet::iterator I = CleanedNodes.begin(), |
| E = CleanedNodes.end(); I != E; ++I) { |
| |
| // Step 4: Generate the CallExit and leave the callee's context. |
| // CleanedNodes -> CEENode |
| CallExitEnd Loc(calleeCtx, callerCtx); |
| bool isNew; |
| ProgramStateRef CEEState = (*I == CEBNode) ? state : (*I)->getState(); |
| ExplodedNode *CEENode = G.getNode(Loc, CEEState, false, &isNew); |
| CEENode->addPredecessor(*I, G); |
| if (!isNew) |
| return; |
| |
| // Step 5: Perform the post-condition check of the CallExpr and enqueue the |
| // result onto the work list. |
| // CEENode -> Dst -> WorkList |
| ExplodedNodeSet Dst; |
| NodeBuilderContext Ctx(Engine, calleeCtx->getCallSiteBlock(), CEENode); |
| SaveAndRestore<const NodeBuilderContext*> NBCSave(currentBuilderContext, |
| &Ctx); |
| SaveAndRestore<unsigned> CBISave(currentStmtIdx, calleeCtx->getIndex()); |
| |
| // FIXME: This needs to call PostCall. |
| // FIXME: If/when we inline Objective-C messages, this also needs to call |
| // PostObjCMessage. |
| if (CE) |
| getCheckerManager().runCheckersForPostStmt(Dst, CEENode, CE, *this, true); |
| else |
| Dst.Add(CEENode); |
| |
| // Enqueue the next element in the block. |
| for (ExplodedNodeSet::iterator PSI = Dst.begin(), PSE = Dst.end(); |
| PSI != PSE; ++PSI) { |
| Engine.getWorkList()->enqueue(*PSI, calleeCtx->getCallSiteBlock(), |
| calleeCtx->getIndex()+1); |
| } |
| } |
| } |
| |
| static unsigned getNumberStackFrames(const LocationContext *LCtx) { |
| unsigned count = 0; |
| while (LCtx) { |
| if (isa<StackFrameContext>(LCtx)) |
| ++count; |
| LCtx = LCtx->getParent(); |
| } |
| return count; |
| } |
| |
| // Determine if we should inline the call. |
| bool ExprEngine::shouldInlineDecl(const Decl *D, ExplodedNode *Pred) { |
| AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); |
| const CFG *CalleeCFG = CalleeADC->getCFG(); |
| |
| // It is possible that the CFG cannot be constructed. |
| // Be safe, and check if the CalleeCFG is valid. |
| if (!CalleeCFG) |
| return false; |
| |
| if (getNumberStackFrames(Pred->getLocationContext()) |
| == AMgr.InlineMaxStackDepth) |
| return false; |
| |
| if (Engine.FunctionSummaries->hasReachedMaxBlockCount(D)) |
| return false; |
| |
| if (CalleeCFG->getNumBlockIDs() > AMgr.InlineMaxFunctionSize) |
| return false; |
| |
| // Do not inline variadic calls (for now). |
| if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) { |
| if (BD->isVariadic()) |
| return false; |
| } |
| else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { |
| if (FD->isVariadic()) |
| return false; |
| } |
| |
| // It is possible that the live variables analysis cannot be |
| // run. If so, bail out. |
| if (!CalleeADC->getAnalysis<RelaxedLiveVariables>()) |
| return false; |
| |
| return true; |
| } |
| |
| bool ExprEngine::inlineCall(const CallEvent &Call, |
| ExplodedNode *Pred) { |
| if (!getAnalysisManager().shouldInlineCall()) |
| return false; |
| |
| const Decl *D = Call.getRuntimeDefinition(); |
| if (!D) |
| return false; |
| |
| const LocationContext *CurLC = Pred->getLocationContext(); |
| const StackFrameContext *CallerSFC = CurLC->getCurrentStackFrame(); |
| const LocationContext *ParentOfCallee = 0; |
| |
| switch (Call.getKind()) { |
| case CE_Function: |
| case CE_CXXMember: |
| case CE_CXXMemberOperator: |
| // These are always at least possible to inline. |
| break; |
| case CE_CXXConstructor: |
| case CE_CXXDestructor: { |
| // Only inline constructors and destructors if we built the CFGs for them |
| // properly. |
| const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext(); |
| if (!ADC->getCFGBuildOptions().AddImplicitDtors || |
| !ADC->getCFGBuildOptions().AddInitializers) |
| return false; |
| break; |
| } |
| case CE_CXXAllocator: |
| // Do not inline allocators until we model deallocators. |
| // This is unfortunate, but basically necessary for smart pointers and such. |
| return false; |
| case CE_Block: { |
| const BlockDataRegion *BR = cast<BlockCall>(Call).getBlockRegion(); |
| assert(BR && "If we have the block definition we should have its region"); |
| AnalysisDeclContext *BlockCtx = AMgr.getAnalysisDeclContext(D); |
| ParentOfCallee = BlockCtx->getBlockInvocationContext(CallerSFC, |
| cast<BlockDecl>(D), |
| BR); |
| break; |
| } |
| case CE_ObjCMessage: |
| break; |
| } |
| |
| if (!shouldInlineDecl(D, Pred)) |
| return false; |
| |
| if (!ParentOfCallee) |
| ParentOfCallee = CallerSFC; |
| |
| // This may be NULL, but that's fine. |
| const Expr *CallE = Call.getOriginExpr(); |
| |
| // Construct a new stack frame for the callee. |
| AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D); |
| const StackFrameContext *CalleeSFC = |
| CalleeADC->getStackFrame(ParentOfCallee, CallE, |
| currentBuilderContext->getBlock(), |
| currentStmtIdx); |
| |
| CallEnter Loc(CallE, CalleeSFC, CurLC); |
| |
| // Construct a new state which contains the mapping from actual to |
| // formal arguments. |
| ProgramStateRef State = Pred->getState()->enterStackFrame(Call, CalleeSFC); |
| |
| bool isNew; |
| if (ExplodedNode *N = G.getNode(Loc, State, false, &isNew)) { |
| N->addPredecessor(Pred, G); |
| if (isNew) |
| Engine.getWorkList()->enqueue(N); |
| } |
| return true; |
| } |
| |
| static ProgramStateRef getInlineFailedState(ProgramStateRef State, |
| const Stmt *CallE) { |
| void *ReplayState = State->get<ReplayWithoutInlining>(); |
| if (!ReplayState) |
| return 0; |
| |
| assert(ReplayState == (const void*)CallE && "Backtracked to the wrong call."); |
| (void)CallE; |
| |
| return State->remove<ReplayWithoutInlining>(); |
| } |
| |
| void ExprEngine::VisitCallExpr(const CallExpr *CE, ExplodedNode *Pred, |
| ExplodedNodeSet &dst) { |
| // Perform the previsit of the CallExpr. |
| ExplodedNodeSet dstPreVisit; |
| getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, CE, *this); |
| |
| // Get the callee kind. |
| CallEventKind K = classifyCallExpr(CE); |
| |
| // Evaluate the function call. We try each of the checkers |
| // to see if the can evaluate the function call. |
| ExplodedNodeSet dstCallEvaluated; |
| for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); |
| I != E; ++I) { |
| ProgramStateRef State = (*I)->getState(); |
| const LocationContext *LCtx = (*I)->getLocationContext(); |
| |
| // Evaluate the call. |
| switch (K) { |
| case CE_Function: |
| evalCall(dstCallEvaluated, *I, FunctionCall(CE, State, LCtx)); |
| break; |
| case CE_CXXMember: |
| evalCall(dstCallEvaluated, *I, CXXMemberCall(cast<CXXMemberCallExpr>(CE), |
| State, LCtx)); |
| break; |
| case CE_CXXMemberOperator: |
| evalCall(dstCallEvaluated, *I, |
| CXXMemberOperatorCall(cast<CXXOperatorCallExpr>(CE), |
| State, LCtx)); |
| break; |
| case CE_Block: |
| evalCall(dstCallEvaluated, *I, BlockCall(CE, State, LCtx)); |
| break; |
| default: |
| llvm_unreachable("Non-CallExpr CallEventKind"); |
| } |
| } |
| |
| // Finally, perform the post-condition check of the CallExpr and store |
| // the created nodes in 'Dst'. |
| // Note that if the call was inlined, dstCallEvaluated will be empty. |
| // The post-CallExpr check will occur in processCallExit. |
| getCheckerManager().runCheckersForPostStmt(dst, dstCallEvaluated, CE, |
| *this); |
| } |
| |
| void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred, |
| const SimpleCall &Call) { |
| // Run any pre-call checks using the generic call interface. |
| ExplodedNodeSet dstPreVisit; |
| getCheckerManager().runCheckersForPreCall(dstPreVisit, Pred, Call, *this); |
| |
| // Actually evaluate the function call. We try each of the checkers |
| // to see if the can evaluate the function call, and get a callback at |
| // defaultEvalCall if all of them fail. |
| ExplodedNodeSet dstCallEvaluated; |
| getCheckerManager().runCheckersForEvalCall(dstCallEvaluated, dstPreVisit, |
| Call, *this); |
| |
| // Finally, run any post-call checks. |
| getCheckerManager().runCheckersForPostCall(Dst, dstCallEvaluated, |
| Call, *this); |
| } |
| |
| ProgramStateRef ExprEngine::bindReturnValue(const CallEvent &Call, |
| const LocationContext *LCtx, |
| ProgramStateRef State) { |
| const Expr *E = Call.getOriginExpr(); |
| if (!E) |
| return State; |
| |
| // Some method families have known return values. |
| if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) { |
| switch (Msg->getMethodFamily()) { |
| default: |
| break; |
| case OMF_autorelease: |
| case OMF_retain: |
| case OMF_self: { |
| // These methods return their receivers. |
| return State->BindExpr(E, LCtx, Msg->getReceiverSVal()); |
| } |
| } |
| } |
| |
| // Conjure a symbol if the return value is unknown. |
| QualType ResultTy = Call.getResultType(); |
| SValBuilder &SVB = getSValBuilder(); |
| unsigned Count = currentBuilderContext->getCurrentBlockCount(); |
| SVal R = SVB.getConjuredSymbolVal(0, E, LCtx, ResultTy, Count); |
| return State->BindExpr(E, LCtx, R); |
| } |
| |
| void ExprEngine::defaultEvalCall(NodeBuilder &Bldr, ExplodedNode *Pred, |
| const CallEvent &Call) { |
| ProgramStateRef State = 0; |
| const Expr *E = Call.getOriginExpr(); |
| |
| // Try to inline the call. |
| // The origin expression here is just used as a kind of checksum; |
| // for CallEvents that do not have origin expressions, this should still be |
| // safe. |
| State = getInlineFailedState(Pred->getState(), E); |
| if (State == 0 && inlineCall(Call, Pred)) { |
| // If we inlined the call, the successor has been manually added onto |
| // the work list and we should not consider it for subsequent call |
| // handling steps. |
| Bldr.takeNodes(Pred); |
| return; |
| } |
| |
| // If we can't inline it, handle the return value and invalidate the regions. |
| if (State == 0) |
| State = Pred->getState(); |
| |
| // Invalidate any regions touched by the call. |
| unsigned Count = currentBuilderContext->getCurrentBlockCount(); |
| State = Call.invalidateRegions(Count, State); |
| |
| // Construct and bind the return value. |
| State = bindReturnValue(Call, Pred->getLocationContext(), State); |
| |
| // And make the result node. |
| Bldr.generateNode(Call.getProgramPoint(), State, Pred); |
| } |
| |
| void ExprEngine::VisitReturnStmt(const ReturnStmt *RS, ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| |
| ExplodedNodeSet dstPreVisit; |
| getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, RS, *this); |
| |
| StmtNodeBuilder B(dstPreVisit, Dst, *currentBuilderContext); |
| |
| if (RS->getRetValue()) { |
| for (ExplodedNodeSet::iterator it = dstPreVisit.begin(), |
| ei = dstPreVisit.end(); it != ei; ++it) { |
| B.generateNode(RS, *it, (*it)->getState()); |
| } |
| } |
| } |