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Current File : //compat/linux/proc/68247/root/usr/src/contrib/llvm/tools/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp |
//=-- ExprEngine.cpp - Path-Sensitive Expression-Level Dataflow ---*- 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 a meta-engine for path-sensitive dataflow analysis that // is built on GREngine, but provides the boilerplate to execute transfer // functions and build the ExplodedGraph at the expression level. // //===----------------------------------------------------------------------===// #define DEBUG_TYPE "ExprEngine" #include "clang/StaticAnalyzer/Core/CheckerManager.h" #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h" #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" #include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h" #include "clang/AST/CharUnits.h" #include "clang/AST/ParentMap.h" #include "clang/AST/StmtObjC.h" #include "clang/AST/StmtCXX.h" #include "clang/AST/DeclCXX.h" #include "clang/Basic/Builtins.h" #include "clang/Basic/SourceManager.h" #include "clang/Basic/PrettyStackTrace.h" #include "llvm/Support/raw_ostream.h" #include "llvm/ADT/ImmutableList.h" #include "llvm/ADT/Statistic.h" #ifndef NDEBUG #include "llvm/Support/GraphWriter.h" #endif using namespace clang; using namespace ento; using llvm::APSInt; STATISTIC(NumRemoveDeadBindings, "The # of times RemoveDeadBindings is called"); STATISTIC(NumRemoveDeadBindingsSkipped, "The # of times RemoveDeadBindings is skipped"); STATISTIC(NumMaxBlockCountReached, "The # of aborted paths due to reaching the maximum block count in " "a top level function"); STATISTIC(NumMaxBlockCountReachedInInlined, "The # of aborted paths due to reaching the maximum block count in " "an inlined function"); STATISTIC(NumTimesRetriedWithoutInlining, "The # of times we re-evaluated a call without inlining"); //===----------------------------------------------------------------------===// // Utility functions. //===----------------------------------------------------------------------===// static inline Selector GetNullarySelector(const char* name, ASTContext &Ctx) { IdentifierInfo* II = &Ctx.Idents.get(name); return Ctx.Selectors.getSelector(0, &II); } //===----------------------------------------------------------------------===// // Engine construction and deletion. //===----------------------------------------------------------------------===// ExprEngine::ExprEngine(AnalysisManager &mgr, bool gcEnabled, SetOfConstDecls *VisitedCallees, FunctionSummariesTy *FS) : AMgr(mgr), AnalysisDeclContexts(mgr.getAnalysisDeclContextManager()), Engine(*this, VisitedCallees, FS), G(Engine.getGraph()), StateMgr(getContext(), mgr.getStoreManagerCreator(), mgr.getConstraintManagerCreator(), G.getAllocator(), *this), SymMgr(StateMgr.getSymbolManager()), svalBuilder(StateMgr.getSValBuilder()), EntryNode(NULL), currentStmt(NULL), currentStmtIdx(0), currentBuilderContext(0), NSExceptionII(NULL), NSExceptionInstanceRaiseSelectors(NULL), RaiseSel(GetNullarySelector("raise", getContext())), ObjCGCEnabled(gcEnabled), BR(mgr, *this) { if (mgr.shouldEagerlyTrimExplodedGraph()) { // Enable eager node reclaimation when constructing the ExplodedGraph. G.enableNodeReclamation(); } } ExprEngine::~ExprEngine() { BR.FlushReports(); delete [] NSExceptionInstanceRaiseSelectors; } //===----------------------------------------------------------------------===// // Utility methods. //===----------------------------------------------------------------------===// ProgramStateRef ExprEngine::getInitialState(const LocationContext *InitLoc) { ProgramStateRef state = StateMgr.getInitialState(InitLoc); const Decl *D = InitLoc->getDecl(); // Preconditions. // FIXME: It would be nice if we had a more general mechanism to add // such preconditions. Some day. do { if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { // Precondition: the first argument of 'main' is an integer guaranteed // to be > 0. const IdentifierInfo *II = FD->getIdentifier(); if (!II || !(II->getName() == "main" && FD->getNumParams() > 0)) break; const ParmVarDecl *PD = FD->getParamDecl(0); QualType T = PD->getType(); if (!T->isIntegerType()) break; const MemRegion *R = state->getRegion(PD, InitLoc); if (!R) break; SVal V = state->getSVal(loc::MemRegionVal(R)); SVal Constraint_untested = evalBinOp(state, BO_GT, V, svalBuilder.makeZeroVal(T), getContext().IntTy); DefinedOrUnknownSVal *Constraint = dyn_cast<DefinedOrUnknownSVal>(&Constraint_untested); if (!Constraint) break; if (ProgramStateRef newState = state->assume(*Constraint, true)) state = newState; } break; } while (0); if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) { // Precondition: 'self' is always non-null upon entry to an Objective-C // method. const ImplicitParamDecl *SelfD = MD->getSelfDecl(); const MemRegion *R = state->getRegion(SelfD, InitLoc); SVal V = state->getSVal(loc::MemRegionVal(R)); if (const Loc *LV = dyn_cast<Loc>(&V)) { // Assume that the pointer value in 'self' is non-null. state = state->assume(*LV, true); assert(state && "'self' cannot be null"); } } if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) { if (!MD->isStatic()) { // Precondition: 'this' is always non-null upon entry to the // top-level function. This is our starting assumption for // analyzing an "open" program. const StackFrameContext *SFC = InitLoc->getCurrentStackFrame(); if (SFC->getParent() == 0) { loc::MemRegionVal L(getCXXThisRegion(MD, SFC)); SVal V = state->getSVal(L); if (const Loc *LV = dyn_cast<Loc>(&V)) { state = state->assume(*LV, true); assert(state && "'this' cannot be null"); } } } } return state; } //===----------------------------------------------------------------------===// // Top-level transfer function logic (Dispatcher). //===----------------------------------------------------------------------===// /// evalAssume - Called by ConstraintManager. Used to call checker-specific /// logic for handling assumptions on symbolic values. ProgramStateRef ExprEngine::processAssume(ProgramStateRef state, SVal cond, bool assumption) { return getCheckerManager().runCheckersForEvalAssume(state, cond, assumption); } bool ExprEngine::wantsRegionChangeUpdate(ProgramStateRef state) { return getCheckerManager().wantsRegionChangeUpdate(state); } ProgramStateRef ExprEngine::processRegionChanges(ProgramStateRef state, const StoreManager::InvalidatedSymbols *invalidated, ArrayRef<const MemRegion *> Explicits, ArrayRef<const MemRegion *> Regions, const CallOrObjCMessage *Call) { return getCheckerManager().runCheckersForRegionChanges(state, invalidated, Explicits, Regions, Call); } void ExprEngine::printState(raw_ostream &Out, ProgramStateRef State, const char *NL, const char *Sep) { getCheckerManager().runCheckersForPrintState(Out, State, NL, Sep); } void ExprEngine::processEndWorklist(bool hasWorkRemaining) { getCheckerManager().runCheckersForEndAnalysis(G, BR, *this); } void ExprEngine::processCFGElement(const CFGElement E, ExplodedNode *Pred, unsigned StmtIdx, NodeBuilderContext *Ctx) { currentStmtIdx = StmtIdx; currentBuilderContext = Ctx; switch (E.getKind()) { case CFGElement::Invalid: llvm_unreachable("Unexpected CFGElement kind."); case CFGElement::Statement: ProcessStmt(const_cast<Stmt*>(E.getAs<CFGStmt>()->getStmt()), Pred); return; case CFGElement::Initializer: ProcessInitializer(E.getAs<CFGInitializer>()->getInitializer(), Pred); return; case CFGElement::AutomaticObjectDtor: case CFGElement::BaseDtor: case CFGElement::MemberDtor: case CFGElement::TemporaryDtor: ProcessImplicitDtor(*E.getAs<CFGImplicitDtor>(), Pred); return; } } static bool shouldRemoveDeadBindings(AnalysisManager &AMgr, const CFGStmt S, const ExplodedNode *Pred, const LocationContext *LC) { // Are we never purging state values? if (AMgr.getPurgeMode() == PurgeNone) return false; // Is this the beginning of a basic block? if (isa<BlockEntrance>(Pred->getLocation())) return true; // Is this on a non-expression? if (!isa<Expr>(S.getStmt())) return true; // Run before processing a call. if (isa<CallExpr>(S.getStmt())) return true; // Is this an expression that is consumed by another expression? If so, // postpone cleaning out the state. ParentMap &PM = LC->getAnalysisDeclContext()->getParentMap(); return !PM.isConsumedExpr(cast<Expr>(S.getStmt())); } void ExprEngine::ProcessStmt(const CFGStmt S, ExplodedNode *Pred) { // Reclaim any unnecessary nodes in the ExplodedGraph. G.reclaimRecentlyAllocatedNodes(); currentStmt = S.getStmt(); PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(), currentStmt->getLocStart(), "Error evaluating statement"); EntryNode = Pred; ProgramStateRef EntryState = EntryNode->getState(); CleanedState = EntryState; // Create the cleaned state. const LocationContext *LC = EntryNode->getLocationContext(); SymbolReaper SymReaper(LC, currentStmt, SymMgr, getStoreManager()); if (shouldRemoveDeadBindings(AMgr, S, Pred, LC)) { NumRemoveDeadBindings++; getCheckerManager().runCheckersForLiveSymbols(CleanedState, SymReaper); const StackFrameContext *SFC = LC->getCurrentStackFrame(); // Create a state in which dead bindings are removed from the environment // and the store. TODO: The function should just return new env and store, // not a new state. CleanedState = StateMgr.removeDeadBindings(CleanedState, SFC, SymReaper); } else { NumRemoveDeadBindingsSkipped++; } // Process any special transfer function for dead symbols. ExplodedNodeSet Tmp; // A tag to track convenience transitions, which can be removed at cleanup. static SimpleProgramPointTag cleanupTag("ExprEngine : Clean Node"); if (!SymReaper.hasDeadSymbols()) { // Generate a CleanedNode that has the environment and store cleaned // up. Since no symbols are dead, we can optimize and not clean out // the constraint manager. StmtNodeBuilder Bldr(Pred, Tmp, *currentBuilderContext); Bldr.generateNode(currentStmt, EntryNode, CleanedState, false, &cleanupTag); } else { // Call checkers with the non-cleaned state so that they could query the // values of the soon to be dead symbols. ExplodedNodeSet CheckedSet; getCheckerManager().runCheckersForDeadSymbols(CheckedSet, EntryNode, SymReaper, currentStmt, *this); // For each node in CheckedSet, generate CleanedNodes that have the // environment, the store, and the constraints cleaned up but have the // user-supplied states as the predecessors. StmtNodeBuilder Bldr(CheckedSet, Tmp, *currentBuilderContext); for (ExplodedNodeSet::const_iterator I = CheckedSet.begin(), E = CheckedSet.end(); I != E; ++I) { ProgramStateRef CheckerState = (*I)->getState(); // The constraint manager has not been cleaned up yet, so clean up now. CheckerState = getConstraintManager().removeDeadBindings(CheckerState, SymReaper); assert(StateMgr.haveEqualEnvironments(CheckerState, EntryState) && "Checkers are not allowed to modify the Environment as a part of " "checkDeadSymbols processing."); assert(StateMgr.haveEqualStores(CheckerState, EntryState) && "Checkers are not allowed to modify the Store as a part of " "checkDeadSymbols processing."); // Create a state based on CleanedState with CheckerState GDM and // generate a transition to that state. ProgramStateRef CleanedCheckerSt = StateMgr.getPersistentStateWithGDM(CleanedState, CheckerState); Bldr.generateNode(currentStmt, *I, CleanedCheckerSt, false, &cleanupTag, ProgramPoint::PostPurgeDeadSymbolsKind); } } ExplodedNodeSet Dst; for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) { ExplodedNodeSet DstI; // Visit the statement. Visit(currentStmt, *I, DstI); Dst.insert(DstI); } // Enqueue the new nodes onto the work list. Engine.enqueue(Dst, currentBuilderContext->getBlock(), currentStmtIdx); // NULL out these variables to cleanup. CleanedState = NULL; EntryNode = NULL; currentStmt = 0; } void ExprEngine::ProcessInitializer(const CFGInitializer Init, ExplodedNode *Pred) { ExplodedNodeSet Dst; // We don't set EntryNode and currentStmt. And we don't clean up state. const CXXCtorInitializer *BMI = Init.getInitializer(); const StackFrameContext *stackFrame = cast<StackFrameContext>(Pred->getLocationContext()); const CXXConstructorDecl *decl = cast<CXXConstructorDecl>(stackFrame->getDecl()); const CXXThisRegion *thisReg = getCXXThisRegion(decl, stackFrame); SVal thisVal = Pred->getState()->getSVal(thisReg); if (BMI->isAnyMemberInitializer()) { // Evaluate the initializer. StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); ProgramStateRef state = Pred->getState(); const FieldDecl *FD = BMI->getAnyMember(); SVal FieldLoc = state->getLValue(FD, thisVal); SVal InitVal = state->getSVal(BMI->getInit(), Pred->getLocationContext()); state = state->bindLoc(FieldLoc, InitVal); // Use a custom node building process. PostInitializer PP(BMI, stackFrame); // Builder automatically add the generated node to the deferred set, // which are processed in the builder's dtor. Bldr.generateNode(PP, Pred, state); } else { assert(BMI->isBaseInitializer()); // Get the base class declaration. const CXXConstructExpr *ctorExpr = cast<CXXConstructExpr>(BMI->getInit()); // Create the base object region. SVal baseVal = getStoreManager().evalDerivedToBase(thisVal, ctorExpr->getType()); const MemRegion *baseReg = baseVal.getAsRegion(); assert(baseReg); VisitCXXConstructExpr(ctorExpr, baseReg, Pred, Dst); } // Enqueue the new nodes onto the work list. Engine.enqueue(Dst, currentBuilderContext->getBlock(), currentStmtIdx); } void ExprEngine::ProcessImplicitDtor(const CFGImplicitDtor D, ExplodedNode *Pred) { ExplodedNodeSet Dst; switch (D.getKind()) { case CFGElement::AutomaticObjectDtor: ProcessAutomaticObjDtor(cast<CFGAutomaticObjDtor>(D), Pred, Dst); break; case CFGElement::BaseDtor: ProcessBaseDtor(cast<CFGBaseDtor>(D), Pred, Dst); break; case CFGElement::MemberDtor: ProcessMemberDtor(cast<CFGMemberDtor>(D), Pred, Dst); break; case CFGElement::TemporaryDtor: ProcessTemporaryDtor(cast<CFGTemporaryDtor>(D), Pred, Dst); break; default: llvm_unreachable("Unexpected dtor kind."); } // Enqueue the new nodes onto the work list. Engine.enqueue(Dst, currentBuilderContext->getBlock(), currentStmtIdx); } void ExprEngine::ProcessAutomaticObjDtor(const CFGAutomaticObjDtor Dtor, ExplodedNode *Pred, ExplodedNodeSet &Dst) { ProgramStateRef state = Pred->getState(); const VarDecl *varDecl = Dtor.getVarDecl(); QualType varType = varDecl->getType(); if (const ReferenceType *refType = varType->getAs<ReferenceType>()) varType = refType->getPointeeType(); const CXXRecordDecl *recordDecl = varType->getAsCXXRecordDecl(); assert(recordDecl && "get CXXRecordDecl fail"); const CXXDestructorDecl *dtorDecl = recordDecl->getDestructor(); Loc dest = state->getLValue(varDecl, Pred->getLocationContext()); VisitCXXDestructor(dtorDecl, cast<loc::MemRegionVal>(dest).getRegion(), Dtor.getTriggerStmt(), Pred, Dst); } void ExprEngine::ProcessBaseDtor(const CFGBaseDtor D, ExplodedNode *Pred, ExplodedNodeSet &Dst) {} void ExprEngine::ProcessMemberDtor(const CFGMemberDtor D, ExplodedNode *Pred, ExplodedNodeSet &Dst) {} void ExprEngine::ProcessTemporaryDtor(const CFGTemporaryDtor D, ExplodedNode *Pred, ExplodedNodeSet &Dst) {} void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred, ExplodedNodeSet &DstTop) { PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(), S->getLocStart(), "Error evaluating statement"); ExplodedNodeSet Dst; StmtNodeBuilder Bldr(Pred, DstTop, *currentBuilderContext); // Expressions to ignore. if (const Expr *Ex = dyn_cast<Expr>(S)) S = Ex->IgnoreParens(); // FIXME: add metadata to the CFG so that we can disable // this check when we KNOW that there is no block-level subexpression. // The motivation is that this check requires a hashtable lookup. if (S != currentStmt && Pred->getLocationContext()->getCFG()->isBlkExpr(S)) return; switch (S->getStmtClass()) { // C++ and ARC stuff we don't support yet. case Expr::ObjCIndirectCopyRestoreExprClass: case Stmt::CXXDependentScopeMemberExprClass: case Stmt::CXXPseudoDestructorExprClass: case Stmt::CXXTryStmtClass: case Stmt::CXXTypeidExprClass: case Stmt::CXXUuidofExprClass: case Stmt::CXXUnresolvedConstructExprClass: case Stmt::CXXScalarValueInitExprClass: case Stmt::DependentScopeDeclRefExprClass: case Stmt::UnaryTypeTraitExprClass: case Stmt::BinaryTypeTraitExprClass: case Stmt::TypeTraitExprClass: case Stmt::ArrayTypeTraitExprClass: case Stmt::ExpressionTraitExprClass: case Stmt::UnresolvedLookupExprClass: case Stmt::UnresolvedMemberExprClass: case Stmt::CXXNoexceptExprClass: case Stmt::PackExpansionExprClass: case Stmt::SubstNonTypeTemplateParmPackExprClass: case Stmt::SEHTryStmtClass: case Stmt::SEHExceptStmtClass: case Stmt::LambdaExprClass: case Stmt::SEHFinallyStmtClass: { const ExplodedNode *node = Bldr.generateNode(S, Pred, Pred->getState(), /* sink */ true); Engine.addAbortedBlock(node, currentBuilderContext->getBlock()); break; } // We don't handle default arguments either yet, but we can fake it // for now by just skipping them. case Stmt::SubstNonTypeTemplateParmExprClass: case Stmt::CXXDefaultArgExprClass: break; case Stmt::ParenExprClass: llvm_unreachable("ParenExprs already handled."); case Stmt::GenericSelectionExprClass: llvm_unreachable("GenericSelectionExprs already handled."); // Cases that should never be evaluated simply because they shouldn't // appear in the CFG. case Stmt::BreakStmtClass: case Stmt::CaseStmtClass: case Stmt::CompoundStmtClass: case Stmt::ContinueStmtClass: case Stmt::CXXForRangeStmtClass: case Stmt::DefaultStmtClass: case Stmt::DoStmtClass: case Stmt::ForStmtClass: case Stmt::GotoStmtClass: case Stmt::IfStmtClass: case Stmt::IndirectGotoStmtClass: case Stmt::LabelStmtClass: case Stmt::AttributedStmtClass: case Stmt::NoStmtClass: case Stmt::NullStmtClass: case Stmt::SwitchStmtClass: case Stmt::WhileStmtClass: case Expr::MSDependentExistsStmtClass: llvm_unreachable("Stmt should not be in analyzer evaluation loop"); case Stmt::GNUNullExprClass: { // GNU __null is a pointer-width integer, not an actual pointer. ProgramStateRef state = Pred->getState(); state = state->BindExpr(S, Pred->getLocationContext(), svalBuilder.makeIntValWithPtrWidth(0, false)); Bldr.generateNode(S, Pred, state); break; } case Stmt::ObjCAtSynchronizedStmtClass: Bldr.takeNodes(Pred); VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S), Pred, Dst); Bldr.addNodes(Dst); break; // FIXME. case Stmt::ObjCSubscriptRefExprClass: break; case Stmt::ObjCPropertyRefExprClass: // Implicitly handled by Environment::getSVal(). break; case Stmt::ImplicitValueInitExprClass: { ProgramStateRef state = Pred->getState(); QualType ty = cast<ImplicitValueInitExpr>(S)->getType(); SVal val = svalBuilder.makeZeroVal(ty); Bldr.generateNode(S, Pred, state->BindExpr(S, Pred->getLocationContext(), val)); break; } case Stmt::ExprWithCleanupsClass: // Handled due to fully linearised CFG. break; // Cases not handled yet; but will handle some day. case Stmt::DesignatedInitExprClass: case Stmt::ExtVectorElementExprClass: case Stmt::ImaginaryLiteralClass: case Stmt::ObjCAtCatchStmtClass: case Stmt::ObjCAtFinallyStmtClass: case Stmt::ObjCAtTryStmtClass: case Stmt::ObjCAutoreleasePoolStmtClass: case Stmt::ObjCEncodeExprClass: case Stmt::ObjCIsaExprClass: case Stmt::ObjCProtocolExprClass: case Stmt::ObjCSelectorExprClass: case Expr::ObjCNumericLiteralClass: case Stmt::ParenListExprClass: case Stmt::PredefinedExprClass: case Stmt::ShuffleVectorExprClass: case Stmt::VAArgExprClass: case Stmt::CUDAKernelCallExprClass: case Stmt::OpaqueValueExprClass: case Stmt::AsTypeExprClass: case Stmt::AtomicExprClass: // Fall through. // Currently all handling of 'throw' just falls to the CFG. We // can consider doing more if necessary. case Stmt::CXXThrowExprClass: // Fall through. // Cases we intentionally don't evaluate, since they don't need // to be explicitly evaluated. case Stmt::AddrLabelExprClass: case Stmt::IntegerLiteralClass: case Stmt::CharacterLiteralClass: case Stmt::CXXBoolLiteralExprClass: case Stmt::ObjCBoolLiteralExprClass: case Stmt::FloatingLiteralClass: case Stmt::SizeOfPackExprClass: case Stmt::StringLiteralClass: case Stmt::ObjCStringLiteralClass: case Stmt::CXXBindTemporaryExprClass: case Stmt::CXXNullPtrLiteralExprClass: { Bldr.takeNodes(Pred); ExplodedNodeSet preVisit; getCheckerManager().runCheckersForPreStmt(preVisit, Pred, S, *this); getCheckerManager().runCheckersForPostStmt(Dst, preVisit, S, *this); Bldr.addNodes(Dst); break; } case Expr::ObjCArrayLiteralClass: case Expr::ObjCDictionaryLiteralClass: { Bldr.takeNodes(Pred); ExplodedNodeSet preVisit; getCheckerManager().runCheckersForPreStmt(preVisit, Pred, S, *this); // FIXME: explicitly model with a region and the actual contents // of the container. For now, conjure a symbol. ExplodedNodeSet Tmp; StmtNodeBuilder Bldr2(preVisit, Tmp, *currentBuilderContext); for (ExplodedNodeSet::iterator it = preVisit.begin(), et = preVisit.end(); it != et; ++it) { ExplodedNode *N = *it; const Expr *Ex = cast<Expr>(S); QualType resultType = Ex->getType(); const LocationContext *LCtx = N->getLocationContext(); SVal result = svalBuilder.getConjuredSymbolVal(0, Ex, LCtx, resultType, currentBuilderContext->getCurrentBlockCount()); ProgramStateRef state = N->getState()->BindExpr(Ex, LCtx, result); Bldr2.generateNode(S, N, state); } getCheckerManager().runCheckersForPostStmt(Dst, Tmp, S, *this); Bldr.addNodes(Dst); break; } case Stmt::ArraySubscriptExprClass: Bldr.takeNodes(Pred); VisitLvalArraySubscriptExpr(cast<ArraySubscriptExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::AsmStmtClass: Bldr.takeNodes(Pred); VisitAsmStmt(cast<AsmStmt>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::BlockExprClass: Bldr.takeNodes(Pred); VisitBlockExpr(cast<BlockExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::BinaryOperatorClass: { const BinaryOperator* B = cast<BinaryOperator>(S); if (B->isLogicalOp()) { Bldr.takeNodes(Pred); VisitLogicalExpr(B, Pred, Dst); Bldr.addNodes(Dst); break; } else if (B->getOpcode() == BO_Comma) { ProgramStateRef state = Pred->getState(); Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), state->getSVal(B->getRHS(), Pred->getLocationContext()))); break; } Bldr.takeNodes(Pred); if (AMgr.shouldEagerlyAssume() && (B->isRelationalOp() || B->isEqualityOp())) { ExplodedNodeSet Tmp; VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Tmp); evalEagerlyAssume(Dst, Tmp, cast<Expr>(S)); } else VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::CallExprClass: case Stmt::CXXOperatorCallExprClass: case Stmt::CXXMemberCallExprClass: case Stmt::UserDefinedLiteralClass: { Bldr.takeNodes(Pred); VisitCallExpr(cast<CallExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::CXXCatchStmtClass: { Bldr.takeNodes(Pred); VisitCXXCatchStmt(cast<CXXCatchStmt>(S), Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::CXXTemporaryObjectExprClass: case Stmt::CXXConstructExprClass: { const CXXConstructExpr *C = cast<CXXConstructExpr>(S); // For block-level CXXConstructExpr, we don't have a destination region. // Let VisitCXXConstructExpr() create one. Bldr.takeNodes(Pred); VisitCXXConstructExpr(C, 0, Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::CXXNewExprClass: { Bldr.takeNodes(Pred); const CXXNewExpr *NE = cast<CXXNewExpr>(S); VisitCXXNewExpr(NE, Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::CXXDeleteExprClass: { Bldr.takeNodes(Pred); const CXXDeleteExpr *CDE = cast<CXXDeleteExpr>(S); VisitCXXDeleteExpr(CDE, Pred, Dst); Bldr.addNodes(Dst); break; } // FIXME: ChooseExpr is really a constant. We need to fix // the CFG do not model them as explicit control-flow. case Stmt::ChooseExprClass: { // __builtin_choose_expr Bldr.takeNodes(Pred); const ChooseExpr *C = cast<ChooseExpr>(S); VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::CompoundAssignOperatorClass: Bldr.takeNodes(Pred); VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::CompoundLiteralExprClass: Bldr.takeNodes(Pred); VisitCompoundLiteralExpr(cast<CompoundLiteralExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::BinaryConditionalOperatorClass: case Stmt::ConditionalOperatorClass: { // '?' operator Bldr.takeNodes(Pred); const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(S); VisitGuardedExpr(C, C->getTrueExpr(), C->getFalseExpr(), Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::CXXThisExprClass: Bldr.takeNodes(Pred); VisitCXXThisExpr(cast<CXXThisExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::DeclRefExprClass: { Bldr.takeNodes(Pred); const DeclRefExpr *DE = cast<DeclRefExpr>(S); VisitCommonDeclRefExpr(DE, DE->getDecl(), Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::DeclStmtClass: Bldr.takeNodes(Pred); VisitDeclStmt(cast<DeclStmt>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::ImplicitCastExprClass: case Stmt::CStyleCastExprClass: case Stmt::CXXStaticCastExprClass: case Stmt::CXXDynamicCastExprClass: case Stmt::CXXReinterpretCastExprClass: case Stmt::CXXConstCastExprClass: case Stmt::CXXFunctionalCastExprClass: case Stmt::ObjCBridgedCastExprClass: { Bldr.takeNodes(Pred); const CastExpr *C = cast<CastExpr>(S); // Handle the previsit checks. ExplodedNodeSet dstPrevisit; getCheckerManager().runCheckersForPreStmt(dstPrevisit, Pred, C, *this); // Handle the expression itself. ExplodedNodeSet dstExpr; for (ExplodedNodeSet::iterator i = dstPrevisit.begin(), e = dstPrevisit.end(); i != e ; ++i) { VisitCast(C, C->getSubExpr(), *i, dstExpr); } // Handle the postvisit checks. getCheckerManager().runCheckersForPostStmt(Dst, dstExpr, C, *this); Bldr.addNodes(Dst); break; } case Expr::MaterializeTemporaryExprClass: { Bldr.takeNodes(Pred); const MaterializeTemporaryExpr *Materialize = cast<MaterializeTemporaryExpr>(S); if (Materialize->getType()->isRecordType()) Dst.Add(Pred); else CreateCXXTemporaryObject(Materialize, Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::InitListExprClass: Bldr.takeNodes(Pred); VisitInitListExpr(cast<InitListExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::MemberExprClass: Bldr.takeNodes(Pred); VisitMemberExpr(cast<MemberExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::ObjCIvarRefExprClass: Bldr.takeNodes(Pred); VisitLvalObjCIvarRefExpr(cast<ObjCIvarRefExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::ObjCForCollectionStmtClass: Bldr.takeNodes(Pred); VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::ObjCMessageExprClass: { Bldr.takeNodes(Pred); // Is this a property access? const ParentMap &PM = Pred->getLocationContext()->getParentMap(); const ObjCMessageExpr *ME = cast<ObjCMessageExpr>(S); bool evaluated = false; if (const PseudoObjectExpr *PO = dyn_cast_or_null<PseudoObjectExpr>(PM.getParent(S))) { const Expr *syntactic = PO->getSyntacticForm(); if (const ObjCPropertyRefExpr *PR = dyn_cast<ObjCPropertyRefExpr>(syntactic)) { bool isSetter = ME->getNumArgs() > 0; VisitObjCMessage(ObjCMessage(ME, PR, isSetter), Pred, Dst); evaluated = true; } else if (isa<BinaryOperator>(syntactic)) { VisitObjCMessage(ObjCMessage(ME, 0, true), Pred, Dst); } } if (!evaluated) VisitObjCMessage(ME, Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::ObjCAtThrowStmtClass: { // FIXME: This is not complete. We basically treat @throw as // an abort. Bldr.generateNode(S, Pred, Pred->getState()); break; } case Stmt::ReturnStmtClass: Bldr.takeNodes(Pred); VisitReturnStmt(cast<ReturnStmt>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::OffsetOfExprClass: Bldr.takeNodes(Pred); VisitOffsetOfExpr(cast<OffsetOfExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::UnaryExprOrTypeTraitExprClass: Bldr.takeNodes(Pred); VisitUnaryExprOrTypeTraitExpr(cast<UnaryExprOrTypeTraitExpr>(S), Pred, Dst); Bldr.addNodes(Dst); break; case Stmt::StmtExprClass: { const StmtExpr *SE = cast<StmtExpr>(S); if (SE->getSubStmt()->body_empty()) { // Empty statement expression. assert(SE->getType() == getContext().VoidTy && "Empty statement expression must have void type."); break; } if (Expr *LastExpr = dyn_cast<Expr>(*SE->getSubStmt()->body_rbegin())) { ProgramStateRef state = Pred->getState(); Bldr.generateNode(SE, Pred, state->BindExpr(SE, Pred->getLocationContext(), state->getSVal(LastExpr, Pred->getLocationContext()))); } break; } case Stmt::UnaryOperatorClass: { Bldr.takeNodes(Pred); const UnaryOperator *U = cast<UnaryOperator>(S); if (AMgr.shouldEagerlyAssume() && (U->getOpcode() == UO_LNot)) { ExplodedNodeSet Tmp; VisitUnaryOperator(U, Pred, Tmp); evalEagerlyAssume(Dst, Tmp, U); } else VisitUnaryOperator(U, Pred, Dst); Bldr.addNodes(Dst); break; } case Stmt::PseudoObjectExprClass: { Bldr.takeNodes(Pred); ProgramStateRef state = Pred->getState(); const PseudoObjectExpr *PE = cast<PseudoObjectExpr>(S); if (const Expr *Result = PE->getResultExpr()) { SVal V = state->getSVal(Result, Pred->getLocationContext()); Bldr.generateNode(S, Pred, state->BindExpr(S, Pred->getLocationContext(), V)); } else Bldr.generateNode(S, Pred, state->BindExpr(S, Pred->getLocationContext(), UnknownVal())); Bldr.addNodes(Dst); break; } } } bool ExprEngine::replayWithoutInlining(ExplodedNode *N, const LocationContext *CalleeLC) { const StackFrameContext *CalleeSF = CalleeLC->getCurrentStackFrame(); const StackFrameContext *CallerSF = CalleeSF->getParent()->getCurrentStackFrame(); assert(CalleeSF && CallerSF); ExplodedNode *BeforeProcessingCall = 0; // Find the first node before we started processing the call expression. while (N) { ProgramPoint L = N->getLocation(); BeforeProcessingCall = N; N = N->pred_empty() ? NULL : *(N->pred_begin()); // Skip the nodes corresponding to the inlined code. if (L.getLocationContext()->getCurrentStackFrame() != CallerSF) continue; // We reached the caller. Find the node right before we started // processing the CallExpr. if (isa<PostPurgeDeadSymbols>(L)) continue; if (const StmtPoint *SP = dyn_cast<StmtPoint>(&L)) if (SP->getStmt() == CalleeSF->getCallSite()) continue; break; } if (!BeforeProcessingCall) return false; // TODO: Clean up the unneeded nodes. // Build an Epsilon node from which we will restart the analyzes. const Stmt *CE = CalleeSF->getCallSite(); ProgramPoint NewNodeLoc = EpsilonPoint(BeforeProcessingCall->getLocationContext(), CE); // Add the special flag to GDM to signal retrying with no inlining. // Note, changing the state ensures that we are not going to cache out. ProgramStateRef NewNodeState = BeforeProcessingCall->getState(); NewNodeState = NewNodeState->set<ReplayWithoutInlining>((void*)CE); // Make the new node a successor of BeforeProcessingCall. bool IsNew = false; ExplodedNode *NewNode = G.getNode(NewNodeLoc, NewNodeState, false, &IsNew); // We cached out at this point. Caching out is common due to us backtracking // from the inlined function, which might spawn several paths. if (!IsNew) return true; NewNode->addPredecessor(BeforeProcessingCall, G); // Add the new node to the work list. Engine.enqueueStmtNode(NewNode, CalleeSF->getCallSiteBlock(), CalleeSF->getIndex()); NumTimesRetriedWithoutInlining++; return true; } /// Block entrance. (Update counters). void ExprEngine::processCFGBlockEntrance(const BlockEdge &L, NodeBuilderWithSinks &nodeBuilder) { // FIXME: Refactor this into a checker. ExplodedNode *pred = nodeBuilder.getContext().getPred(); if (nodeBuilder.getContext().getCurrentBlockCount() >= AMgr.getMaxVisit()) { static SimpleProgramPointTag tag("ExprEngine : Block count exceeded"); const ExplodedNode *Sink = nodeBuilder.generateNode(pred->getState(), pred, &tag, true); // Check if we stopped at the top level function or not. // Root node should have the location context of the top most function. const LocationContext *CalleeLC = pred->getLocation().getLocationContext(); const LocationContext *CalleeSF = CalleeLC->getCurrentStackFrame(); const LocationContext *RootLC = (*G.roots_begin())->getLocation().getLocationContext(); if (RootLC->getCurrentStackFrame() != CalleeSF) { Engine.FunctionSummaries->markReachedMaxBlockCount(CalleeSF->getDecl()); // Re-run the call evaluation without inlining it, by storing the // no-inlining policy in the state and enqueuing the new work item on // the list. Replay should almost never fail. Use the stats to catch it // if it does. if ((!AMgr.NoRetryExhausted && replayWithoutInlining(pred, CalleeLC))) return; NumMaxBlockCountReachedInInlined++; } else NumMaxBlockCountReached++; // Make sink nodes as exhausted(for stats) only if retry failed. Engine.blocksExhausted.push_back(std::make_pair(L, Sink)); } } //===----------------------------------------------------------------------===// // Branch processing. //===----------------------------------------------------------------------===// ProgramStateRef ExprEngine::MarkBranch(ProgramStateRef state, const Stmt *Terminator, const LocationContext *LCtx, bool branchTaken) { switch (Terminator->getStmtClass()) { default: return state; case Stmt::BinaryOperatorClass: { // '&&' and '||' const BinaryOperator* B = cast<BinaryOperator>(Terminator); BinaryOperator::Opcode Op = B->getOpcode(); assert (Op == BO_LAnd || Op == BO_LOr); // For &&, if we take the true branch, then the value of the whole // expression is that of the RHS expression. // // For ||, if we take the false branch, then the value of the whole // expression is that of the RHS expression. const Expr *Ex = (Op == BO_LAnd && branchTaken) || (Op == BO_LOr && !branchTaken) ? B->getRHS() : B->getLHS(); return state->BindExpr(B, LCtx, UndefinedVal(Ex)); } case Stmt::BinaryConditionalOperatorClass: case Stmt::ConditionalOperatorClass: { // ?: const AbstractConditionalOperator* C = cast<AbstractConditionalOperator>(Terminator); // For ?, if branchTaken == true then the value is either the LHS or // the condition itself. (GNU extension). const Expr *Ex; if (branchTaken) Ex = C->getTrueExpr(); else Ex = C->getFalseExpr(); return state->BindExpr(C, LCtx, UndefinedVal(Ex)); } case Stmt::ChooseExprClass: { // ?: const ChooseExpr *C = cast<ChooseExpr>(Terminator); const Expr *Ex = branchTaken ? C->getLHS() : C->getRHS(); return state->BindExpr(C, LCtx, UndefinedVal(Ex)); } } } /// RecoverCastedSymbol - A helper function for ProcessBranch that is used /// to try to recover some path-sensitivity for casts of symbolic /// integers that promote their values (which are currently not tracked well). /// This function returns the SVal bound to Condition->IgnoreCasts if all the // cast(s) did was sign-extend the original value. static SVal RecoverCastedSymbol(ProgramStateManager& StateMgr, ProgramStateRef state, const Stmt *Condition, const LocationContext *LCtx, ASTContext &Ctx) { const Expr *Ex = dyn_cast<Expr>(Condition); if (!Ex) return UnknownVal(); uint64_t bits = 0; bool bitsInit = false; while (const CastExpr *CE = dyn_cast<CastExpr>(Ex)) { QualType T = CE->getType(); if (!T->isIntegerType()) return UnknownVal(); uint64_t newBits = Ctx.getTypeSize(T); if (!bitsInit || newBits < bits) { bitsInit = true; bits = newBits; } Ex = CE->getSubExpr(); } // We reached a non-cast. Is it a symbolic value? QualType T = Ex->getType(); if (!bitsInit || !T->isIntegerType() || Ctx.getTypeSize(T) > bits) return UnknownVal(); return state->getSVal(Ex, LCtx); } void ExprEngine::processBranch(const Stmt *Condition, const Stmt *Term, NodeBuilderContext& BldCtx, ExplodedNode *Pred, ExplodedNodeSet &Dst, const CFGBlock *DstT, const CFGBlock *DstF) { currentBuilderContext = &BldCtx; // Check for NULL conditions; e.g. "for(;;)" if (!Condition) { BranchNodeBuilder NullCondBldr(Pred, Dst, BldCtx, DstT, DstF); NullCondBldr.markInfeasible(false); NullCondBldr.generateNode(Pred->getState(), true, Pred); return; } PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(), Condition->getLocStart(), "Error evaluating branch"); ExplodedNodeSet CheckersOutSet; getCheckerManager().runCheckersForBranchCondition(Condition, CheckersOutSet, Pred, *this); // We generated only sinks. if (CheckersOutSet.empty()) return; BranchNodeBuilder builder(CheckersOutSet, Dst, BldCtx, DstT, DstF); for (NodeBuilder::iterator I = CheckersOutSet.begin(), E = CheckersOutSet.end(); E != I; ++I) { ExplodedNode *PredI = *I; if (PredI->isSink()) continue; ProgramStateRef PrevState = Pred->getState(); SVal X = PrevState->getSVal(Condition, Pred->getLocationContext()); if (X.isUnknownOrUndef()) { // Give it a chance to recover from unknown. if (const Expr *Ex = dyn_cast<Expr>(Condition)) { if (Ex->getType()->isIntegerType()) { // Try to recover some path-sensitivity. Right now casts of symbolic // integers that promote their values are currently not tracked well. // If 'Condition' is such an expression, try and recover the // underlying value and use that instead. SVal recovered = RecoverCastedSymbol(getStateManager(), PrevState, Condition, Pred->getLocationContext(), getContext()); if (!recovered.isUnknown()) { X = recovered; } } } } const LocationContext *LCtx = PredI->getLocationContext(); // If the condition is still unknown, give up. if (X.isUnknownOrUndef()) { builder.generateNode(MarkBranch(PrevState, Term, LCtx, true), true, PredI); builder.generateNode(MarkBranch(PrevState, Term, LCtx, false), false, PredI); continue; } DefinedSVal V = cast<DefinedSVal>(X); // Process the true branch. if (builder.isFeasible(true)) { if (ProgramStateRef state = PrevState->assume(V, true)) builder.generateNode(MarkBranch(state, Term, LCtx, true), true, PredI); else builder.markInfeasible(true); } // Process the false branch. if (builder.isFeasible(false)) { if (ProgramStateRef state = PrevState->assume(V, false)) builder.generateNode(MarkBranch(state, Term, LCtx, false), false, PredI); else builder.markInfeasible(false); } } currentBuilderContext = 0; } /// processIndirectGoto - Called by CoreEngine. Used to generate successor /// nodes by processing the 'effects' of a computed goto jump. void ExprEngine::processIndirectGoto(IndirectGotoNodeBuilder &builder) { ProgramStateRef state = builder.getState(); SVal V = state->getSVal(builder.getTarget(), builder.getLocationContext()); // Three possibilities: // // (1) We know the computed label. // (2) The label is NULL (or some other constant), or Undefined. // (3) We have no clue about the label. Dispatch to all targets. // typedef IndirectGotoNodeBuilder::iterator iterator; if (isa<loc::GotoLabel>(V)) { const LabelDecl *L = cast<loc::GotoLabel>(V).getLabel(); for (iterator I = builder.begin(), E = builder.end(); I != E; ++I) { if (I.getLabel() == L) { builder.generateNode(I, state); return; } } llvm_unreachable("No block with label."); } if (isa<loc::ConcreteInt>(V) || isa<UndefinedVal>(V)) { // Dispatch to the first target and mark it as a sink. //ExplodedNode* N = builder.generateNode(builder.begin(), state, true); // FIXME: add checker visit. // UndefBranches.insert(N); return; } // This is really a catch-all. We don't support symbolics yet. // FIXME: Implement dispatch for symbolic pointers. for (iterator I=builder.begin(), E=builder.end(); I != E; ++I) builder.generateNode(I, state); } /// ProcessEndPath - Called by CoreEngine. Used to generate end-of-path /// nodes when the control reaches the end of a function. void ExprEngine::processEndOfFunction(NodeBuilderContext& BC) { StateMgr.EndPath(BC.Pred->getState()); ExplodedNodeSet Dst; getCheckerManager().runCheckersForEndPath(BC, Dst, *this); Engine.enqueueEndOfFunction(Dst); } /// ProcessSwitch - Called by CoreEngine. Used to generate successor /// nodes by processing the 'effects' of a switch statement. void ExprEngine::processSwitch(SwitchNodeBuilder& builder) { typedef SwitchNodeBuilder::iterator iterator; ProgramStateRef state = builder.getState(); const Expr *CondE = builder.getCondition(); SVal CondV_untested = state->getSVal(CondE, builder.getLocationContext()); if (CondV_untested.isUndef()) { //ExplodedNode* N = builder.generateDefaultCaseNode(state, true); // FIXME: add checker //UndefBranches.insert(N); return; } DefinedOrUnknownSVal CondV = cast<DefinedOrUnknownSVal>(CondV_untested); ProgramStateRef DefaultSt = state; iterator I = builder.begin(), EI = builder.end(); bool defaultIsFeasible = I == EI; for ( ; I != EI; ++I) { // Successor may be pruned out during CFG construction. if (!I.getBlock()) continue; const CaseStmt *Case = I.getCase(); // Evaluate the LHS of the case value. llvm::APSInt V1 = Case->getLHS()->EvaluateKnownConstInt(getContext()); assert(V1.getBitWidth() == getContext().getTypeSize(CondE->getType())); // Get the RHS of the case, if it exists. llvm::APSInt V2; if (const Expr *E = Case->getRHS()) V2 = E->EvaluateKnownConstInt(getContext()); else V2 = V1; // FIXME: Eventually we should replace the logic below with a range // comparison, rather than concretize the values within the range. // This should be easy once we have "ranges" for NonLVals. do { nonloc::ConcreteInt CaseVal(getBasicVals().getValue(V1)); DefinedOrUnknownSVal Res = svalBuilder.evalEQ(DefaultSt ? DefaultSt : state, CondV, CaseVal); // Now "assume" that the case matches. if (ProgramStateRef stateNew = state->assume(Res, true)) { builder.generateCaseStmtNode(I, stateNew); // If CondV evaluates to a constant, then we know that this // is the *only* case that we can take, so stop evaluating the // others. if (isa<nonloc::ConcreteInt>(CondV)) return; } // Now "assume" that the case doesn't match. Add this state // to the default state (if it is feasible). if (DefaultSt) { if (ProgramStateRef stateNew = DefaultSt->assume(Res, false)) { defaultIsFeasible = true; DefaultSt = stateNew; } else { defaultIsFeasible = false; DefaultSt = NULL; } } // Concretize the next value in the range. if (V1 == V2) break; ++V1; assert (V1 <= V2); } while (true); } if (!defaultIsFeasible) return; // If we have switch(enum value), the default branch is not // feasible if all of the enum constants not covered by 'case:' statements // are not feasible values for the switch condition. // // Note that this isn't as accurate as it could be. Even if there isn't // a case for a particular enum value as long as that enum value isn't // feasible then it shouldn't be considered for making 'default:' reachable. const SwitchStmt *SS = builder.getSwitch(); const Expr *CondExpr = SS->getCond()->IgnoreParenImpCasts(); if (CondExpr->getType()->getAs<EnumType>()) { if (SS->isAllEnumCasesCovered()) return; } builder.generateDefaultCaseNode(DefaultSt); } //===----------------------------------------------------------------------===// // Transfer functions: Loads and stores. //===----------------------------------------------------------------------===// void ExprEngine::VisitCommonDeclRefExpr(const Expr *Ex, const NamedDecl *D, ExplodedNode *Pred, ExplodedNodeSet &Dst) { StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); ProgramStateRef state = Pred->getState(); const LocationContext *LCtx = Pred->getLocationContext(); if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { assert(Ex->isLValue()); SVal V = state->getLValue(VD, Pred->getLocationContext()); // For references, the 'lvalue' is the pointer address stored in the // reference region. if (VD->getType()->isReferenceType()) { if (const MemRegion *R = V.getAsRegion()) V = state->getSVal(R); else V = UnknownVal(); } Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V), false, 0, ProgramPoint::PostLValueKind); return; } if (const EnumConstantDecl *ED = dyn_cast<EnumConstantDecl>(D)) { assert(!Ex->isLValue()); SVal V = svalBuilder.makeIntVal(ED->getInitVal()); Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V)); return; } if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { SVal V = svalBuilder.getFunctionPointer(FD); Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V), false, 0, ProgramPoint::PostLValueKind); return; } if (isa<FieldDecl>(D)) { // FIXME: Compute lvalue of fields. Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, UnknownVal()), false, 0, ProgramPoint::PostLValueKind); return; } assert (false && "ValueDecl support for this ValueDecl not implemented."); } /// VisitArraySubscriptExpr - Transfer function for array accesses void ExprEngine::VisitLvalArraySubscriptExpr(const ArraySubscriptExpr *A, ExplodedNode *Pred, ExplodedNodeSet &Dst){ const Expr *Base = A->getBase()->IgnoreParens(); const Expr *Idx = A->getIdx()->IgnoreParens(); ExplodedNodeSet checkerPreStmt; getCheckerManager().runCheckersForPreStmt(checkerPreStmt, Pred, A, *this); StmtNodeBuilder Bldr(checkerPreStmt, Dst, *currentBuilderContext); for (ExplodedNodeSet::iterator it = checkerPreStmt.begin(), ei = checkerPreStmt.end(); it != ei; ++it) { const LocationContext *LCtx = (*it)->getLocationContext(); ProgramStateRef state = (*it)->getState(); SVal V = state->getLValue(A->getType(), state->getSVal(Idx, LCtx), state->getSVal(Base, LCtx)); assert(A->isLValue()); Bldr.generateNode(A, *it, state->BindExpr(A, LCtx, V), false, 0, ProgramPoint::PostLValueKind); } } /// VisitMemberExpr - Transfer function for member expressions. void ExprEngine::VisitMemberExpr(const MemberExpr *M, ExplodedNode *Pred, ExplodedNodeSet &TopDst) { StmtNodeBuilder Bldr(Pred, TopDst, *currentBuilderContext); ExplodedNodeSet Dst; Decl *member = M->getMemberDecl(); if (VarDecl *VD = dyn_cast<VarDecl>(member)) { assert(M->isLValue()); Bldr.takeNodes(Pred); VisitCommonDeclRefExpr(M, VD, Pred, Dst); Bldr.addNodes(Dst); return; } FieldDecl *field = dyn_cast<FieldDecl>(member); if (!field) // FIXME: skipping member expressions for non-fields return; Expr *baseExpr = M->getBase()->IgnoreParens(); ProgramStateRef state = Pred->getState(); const LocationContext *LCtx = Pred->getLocationContext(); SVal baseExprVal = state->getSVal(baseExpr, Pred->getLocationContext()); if (isa<nonloc::LazyCompoundVal>(baseExprVal) || isa<nonloc::CompoundVal>(baseExprVal) || // FIXME: This can originate by conjuring a symbol for an unknown // temporary struct object, see test/Analysis/fields.c: // (p = getit()).x isa<nonloc::SymbolVal>(baseExprVal)) { Bldr.generateNode(M, Pred, state->BindExpr(M, LCtx, UnknownVal())); return; } // FIXME: Should we insert some assumption logic in here to determine // if "Base" is a valid piece of memory? Before we put this assumption // later when using FieldOffset lvals (which we no longer have). // For all other cases, compute an lvalue. SVal L = state->getLValue(field, baseExprVal); if (M->isLValue()) Bldr.generateNode(M, Pred, state->BindExpr(M, LCtx, L), false, 0, ProgramPoint::PostLValueKind); else { Bldr.takeNodes(Pred); evalLoad(Dst, M, M, Pred, state, L); Bldr.addNodes(Dst); } } /// evalBind - Handle the semantics of binding a value to a specific location. /// This method is used by evalStore and (soon) VisitDeclStmt, and others. void ExprEngine::evalBind(ExplodedNodeSet &Dst, const Stmt *StoreE, ExplodedNode *Pred, SVal location, SVal Val, bool atDeclInit) { // Do a previsit of the bind. ExplodedNodeSet CheckedSet; getCheckerManager().runCheckersForBind(CheckedSet, Pred, location, Val, StoreE, *this, ProgramPoint::PostStmtKind); ExplodedNodeSet TmpDst; StmtNodeBuilder Bldr(CheckedSet, TmpDst, *currentBuilderContext); const LocationContext *LC = Pred->getLocationContext(); for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end(); I!=E; ++I) { ExplodedNode *PredI = *I; ProgramStateRef state = PredI->getState(); if (atDeclInit) { const VarRegion *VR = cast<VarRegion>(cast<loc::MemRegionVal>(location).getRegion()); state = state->bindDecl(VR, Val); } else { state = state->bindLoc(location, Val); } const MemRegion *LocReg = 0; if (loc::MemRegionVal *LocRegVal = dyn_cast<loc::MemRegionVal>(&location)) LocReg = LocRegVal->getRegion(); const ProgramPoint L = PostStore(StoreE, LC, LocReg, 0); Bldr.generateNode(L, PredI, state, false); } Dst.insert(TmpDst); } /// evalStore - Handle the semantics of a store via an assignment. /// @param Dst The node set to store generated state nodes /// @param AssignE The assignment expression if the store happens in an /// assignment. /// @param LocatioinE The location expression that is stored to. /// @param state The current simulation state /// @param location The location to store the value /// @param Val The value to be stored void ExprEngine::evalStore(ExplodedNodeSet &Dst, const Expr *AssignE, const Expr *LocationE, ExplodedNode *Pred, ProgramStateRef state, SVal location, SVal Val, const ProgramPointTag *tag) { // Proceed with the store. We use AssignE as the anchor for the PostStore // ProgramPoint if it is non-NULL, and LocationE otherwise. const Expr *StoreE = AssignE ? AssignE : LocationE; if (isa<loc::ObjCPropRef>(location)) { assert(false); } // Evaluate the location (checks for bad dereferences). ExplodedNodeSet Tmp; evalLocation(Tmp, AssignE, LocationE, Pred, state, location, tag, false); if (Tmp.empty()) return; if (location.isUndef()) return; for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI) evalBind(Dst, StoreE, *NI, location, Val, false); } void ExprEngine::evalLoad(ExplodedNodeSet &Dst, const Expr *NodeEx, const Expr *BoundEx, ExplodedNode *Pred, ProgramStateRef state, SVal location, const ProgramPointTag *tag, QualType LoadTy) { assert(!isa<NonLoc>(location) && "location cannot be a NonLoc."); assert(!isa<loc::ObjCPropRef>(location)); // Are we loading from a region? This actually results in two loads; one // to fetch the address of the referenced value and one to fetch the // referenced value. if (const TypedValueRegion *TR = dyn_cast_or_null<TypedValueRegion>(location.getAsRegion())) { QualType ValTy = TR->getValueType(); if (const ReferenceType *RT = ValTy->getAs<ReferenceType>()) { static SimpleProgramPointTag loadReferenceTag("ExprEngine : Load Reference"); ExplodedNodeSet Tmp; evalLoadCommon(Tmp, NodeEx, BoundEx, Pred, state, location, &loadReferenceTag, getContext().getPointerType(RT->getPointeeType())); // Perform the load from the referenced value. for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end() ; I!=E; ++I) { state = (*I)->getState(); location = state->getSVal(BoundEx, (*I)->getLocationContext()); evalLoadCommon(Dst, NodeEx, BoundEx, *I, state, location, tag, LoadTy); } return; } } evalLoadCommon(Dst, NodeEx, BoundEx, Pred, state, location, tag, LoadTy); } void ExprEngine::evalLoadCommon(ExplodedNodeSet &Dst, const Expr *NodeEx, const Expr *BoundEx, ExplodedNode *Pred, ProgramStateRef state, SVal location, const ProgramPointTag *tag, QualType LoadTy) { assert(NodeEx); assert(BoundEx); // Evaluate the location (checks for bad dereferences). ExplodedNodeSet Tmp; evalLocation(Tmp, NodeEx, BoundEx, Pred, state, location, tag, true); if (Tmp.empty()) return; StmtNodeBuilder Bldr(Tmp, Dst, *currentBuilderContext); if (location.isUndef()) return; // Proceed with the load. for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI) { state = (*NI)->getState(); const LocationContext *LCtx = (*NI)->getLocationContext(); if (location.isUnknown()) { // This is important. We must nuke the old binding. Bldr.generateNode(NodeEx, *NI, state->BindExpr(BoundEx, LCtx, UnknownVal()), false, tag, ProgramPoint::PostLoadKind); } else { if (LoadTy.isNull()) LoadTy = BoundEx->getType(); SVal V = state->getSVal(cast<Loc>(location), LoadTy); Bldr.generateNode(NodeEx, *NI, state->bindExprAndLocation(BoundEx, LCtx, location, V), false, tag, ProgramPoint::PostLoadKind); } } } void ExprEngine::evalLocation(ExplodedNodeSet &Dst, const Stmt *NodeEx, const Stmt *BoundEx, ExplodedNode *Pred, ProgramStateRef state, SVal location, const ProgramPointTag *tag, bool isLoad) { StmtNodeBuilder BldrTop(Pred, Dst, *currentBuilderContext); // Early checks for performance reason. if (location.isUnknown()) { return; } ExplodedNodeSet Src; BldrTop.takeNodes(Pred); StmtNodeBuilder Bldr(Pred, Src, *currentBuilderContext); if (Pred->getState() != state) { // Associate this new state with an ExplodedNode. // FIXME: If I pass null tag, the graph is incorrect, e.g for // int *p; // p = 0; // *p = 0xDEADBEEF; // "p = 0" is not noted as "Null pointer value stored to 'p'" but // instead "int *p" is noted as // "Variable 'p' initialized to a null pointer value" // FIXME: why is 'tag' not used instead of etag? static SimpleProgramPointTag etag("ExprEngine: Location"); Bldr.generateNode(NodeEx, Pred, state, false, &etag); } ExplodedNodeSet Tmp; getCheckerManager().runCheckersForLocation(Tmp, Src, location, isLoad, NodeEx, BoundEx, *this); BldrTop.addNodes(Tmp); } std::pair<const ProgramPointTag *, const ProgramPointTag*> ExprEngine::getEagerlyAssumeTags() { static SimpleProgramPointTag EagerlyAssumeTrue("ExprEngine : Eagerly Assume True"), EagerlyAssumeFalse("ExprEngine : Eagerly Assume False"); return std::make_pair(&EagerlyAssumeTrue, &EagerlyAssumeFalse); } void ExprEngine::evalEagerlyAssume(ExplodedNodeSet &Dst, ExplodedNodeSet &Src, const Expr *Ex) { StmtNodeBuilder Bldr(Src, Dst, *currentBuilderContext); for (ExplodedNodeSet::iterator I=Src.begin(), E=Src.end(); I!=E; ++I) { ExplodedNode *Pred = *I; // Test if the previous node was as the same expression. This can happen // when the expression fails to evaluate to anything meaningful and // (as an optimization) we don't generate a node. ProgramPoint P = Pred->getLocation(); if (!isa<PostStmt>(P) || cast<PostStmt>(P).getStmt() != Ex) { continue; } ProgramStateRef state = Pred->getState(); SVal V = state->getSVal(Ex, Pred->getLocationContext()); nonloc::SymbolVal *SEV = dyn_cast<nonloc::SymbolVal>(&V); if (SEV && SEV->isExpression()) { const std::pair<const ProgramPointTag *, const ProgramPointTag*> &tags = getEagerlyAssumeTags(); // First assume that the condition is true. if (ProgramStateRef StateTrue = state->assume(*SEV, true)) { SVal Val = svalBuilder.makeIntVal(1U, Ex->getType()); StateTrue = StateTrue->BindExpr(Ex, Pred->getLocationContext(), Val); Bldr.generateNode(Ex, Pred, StateTrue, false, tags.first); } // Next, assume that the condition is false. if (ProgramStateRef StateFalse = state->assume(*SEV, false)) { SVal Val = svalBuilder.makeIntVal(0U, Ex->getType()); StateFalse = StateFalse->BindExpr(Ex, Pred->getLocationContext(), Val); Bldr.generateNode(Ex, Pred, StateFalse, false, tags.second); } } } } void ExprEngine::VisitAsmStmt(const AsmStmt *A, ExplodedNode *Pred, ExplodedNodeSet &Dst) { StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); // We have processed both the inputs and the outputs. All of the outputs // should evaluate to Locs. Nuke all of their values. // FIXME: Some day in the future it would be nice to allow a "plug-in" // which interprets the inline asm and stores proper results in the // outputs. ProgramStateRef state = Pred->getState(); for (AsmStmt::const_outputs_iterator OI = A->begin_outputs(), OE = A->end_outputs(); OI != OE; ++OI) { SVal X = state->getSVal(*OI, Pred->getLocationContext()); assert (!isa<NonLoc>(X)); // Should be an Lval, or unknown, undef. if (isa<Loc>(X)) state = state->bindLoc(cast<Loc>(X), UnknownVal()); } Bldr.generateNode(A, Pred, state); } //===----------------------------------------------------------------------===// // Visualization. //===----------------------------------------------------------------------===// #ifndef NDEBUG static ExprEngine* GraphPrintCheckerState; static SourceManager* GraphPrintSourceManager; namespace llvm { template<> struct DOTGraphTraits<ExplodedNode*> : public DefaultDOTGraphTraits { DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} // FIXME: Since we do not cache error nodes in ExprEngine now, this does not // work. static std::string getNodeAttributes(const ExplodedNode *N, void*) { #if 0 // FIXME: Replace with a general scheme to tell if the node is // an error node. if (GraphPrintCheckerState->isImplicitNullDeref(N) || GraphPrintCheckerState->isExplicitNullDeref(N) || GraphPrintCheckerState->isUndefDeref(N) || GraphPrintCheckerState->isUndefStore(N) || GraphPrintCheckerState->isUndefControlFlow(N) || GraphPrintCheckerState->isUndefResult(N) || GraphPrintCheckerState->isBadCall(N) || GraphPrintCheckerState->isUndefArg(N)) return "color=\"red\",style=\"filled\""; if (GraphPrintCheckerState->isNoReturnCall(N)) return "color=\"blue\",style=\"filled\""; #endif return ""; } static std::string getNodeLabel(const ExplodedNode *N, void*){ std::string sbuf; llvm::raw_string_ostream Out(sbuf); // Program Location. ProgramPoint Loc = N->getLocation(); switch (Loc.getKind()) { case ProgramPoint::BlockEntranceKind: Out << "Block Entrance: B" << cast<BlockEntrance>(Loc).getBlock()->getBlockID(); break; case ProgramPoint::BlockExitKind: assert (false); break; case ProgramPoint::CallEnterKind: Out << "CallEnter"; break; case ProgramPoint::CallExitKind: Out << "CallExit"; break; case ProgramPoint::EpsilonKind: Out << "Epsilon Point"; break; default: { if (StmtPoint *L = dyn_cast<StmtPoint>(&Loc)) { const Stmt *S = L->getStmt(); SourceLocation SLoc = S->getLocStart(); Out << S->getStmtClassName() << ' ' << (void*) S << ' '; LangOptions LO; // FIXME. S->printPretty(Out, 0, PrintingPolicy(LO)); if (SLoc.isFileID()) { Out << "\\lline=" << GraphPrintSourceManager->getExpansionLineNumber(SLoc) << " col=" << GraphPrintSourceManager->getExpansionColumnNumber(SLoc) << "\\l"; } if (isa<PreStmt>(Loc)) Out << "\\lPreStmt\\l;"; else if (isa<PostLoad>(Loc)) Out << "\\lPostLoad\\l;"; else if (isa<PostStore>(Loc)) Out << "\\lPostStore\\l"; else if (isa<PostLValue>(Loc)) Out << "\\lPostLValue\\l"; #if 0 // FIXME: Replace with a general scheme to determine // the name of the check. if (GraphPrintCheckerState->isImplicitNullDeref(N)) Out << "\\|Implicit-Null Dereference.\\l"; else if (GraphPrintCheckerState->isExplicitNullDeref(N)) Out << "\\|Explicit-Null Dereference.\\l"; else if (GraphPrintCheckerState->isUndefDeref(N)) Out << "\\|Dereference of undefialied value.\\l"; else if (GraphPrintCheckerState->isUndefStore(N)) Out << "\\|Store to Undefined Loc."; else if (GraphPrintCheckerState->isUndefResult(N)) Out << "\\|Result of operation is undefined."; else if (GraphPrintCheckerState->isNoReturnCall(N)) Out << "\\|Call to function marked \"noreturn\"."; else if (GraphPrintCheckerState->isBadCall(N)) Out << "\\|Call to NULL/Undefined."; else if (GraphPrintCheckerState->isUndefArg(N)) Out << "\\|Argument in call is undefined"; #endif break; } const BlockEdge &E = cast<BlockEdge>(Loc); Out << "Edge: (B" << E.getSrc()->getBlockID() << ", B" << E.getDst()->getBlockID() << ')'; if (const Stmt *T = E.getSrc()->getTerminator()) { SourceLocation SLoc = T->getLocStart(); Out << "\\|Terminator: "; LangOptions LO; // FIXME. E.getSrc()->printTerminator(Out, LO); if (SLoc.isFileID()) { Out << "\\lline=" << GraphPrintSourceManager->getExpansionLineNumber(SLoc) << " col=" << GraphPrintSourceManager->getExpansionColumnNumber(SLoc); } if (isa<SwitchStmt>(T)) { const Stmt *Label = E.getDst()->getLabel(); if (Label) { if (const CaseStmt *C = dyn_cast<CaseStmt>(Label)) { Out << "\\lcase "; LangOptions LO; // FIXME. C->getLHS()->printPretty(Out, 0, PrintingPolicy(LO)); if (const Stmt *RHS = C->getRHS()) { Out << " .. "; RHS->printPretty(Out, 0, PrintingPolicy(LO)); } Out << ":"; } else { assert (isa<DefaultStmt>(Label)); Out << "\\ldefault:"; } } else Out << "\\l(implicit) default:"; } else if (isa<IndirectGotoStmt>(T)) { // FIXME } else { Out << "\\lCondition: "; if (*E.getSrc()->succ_begin() == E.getDst()) Out << "true"; else Out << "false"; } Out << "\\l"; } #if 0 // FIXME: Replace with a general scheme to determine // the name of the check. if (GraphPrintCheckerState->isUndefControlFlow(N)) { Out << "\\|Control-flow based on\\lUndefined value.\\l"; } #endif } } ProgramStateRef state = N->getState(); Out << "\\|StateID: " << (void*) state.getPtr() << " NodeID: " << (void*) N << "\\|"; state->printDOT(Out); Out << "\\l"; if (const ProgramPointTag *tag = Loc.getTag()) { Out << "\\|Tag: " << tag->getTagDescription(); Out << "\\l"; } return Out.str(); } }; } // end llvm namespace #endif #ifndef NDEBUG template <typename ITERATOR> ExplodedNode *GetGraphNode(ITERATOR I) { return *I; } template <> ExplodedNode* GetGraphNode<llvm::DenseMap<ExplodedNode*, Expr*>::iterator> (llvm::DenseMap<ExplodedNode*, Expr*>::iterator I) { return I->first; } #endif void ExprEngine::ViewGraph(bool trim) { #ifndef NDEBUG if (trim) { std::vector<ExplodedNode*> Src; // Flush any outstanding reports to make sure we cover all the nodes. // This does not cause them to get displayed. for (BugReporter::iterator I=BR.begin(), E=BR.end(); I!=E; ++I) const_cast<BugType*>(*I)->FlushReports(BR); // Iterate through the reports and get their nodes. for (BugReporter::EQClasses_iterator EI = BR.EQClasses_begin(), EE = BR.EQClasses_end(); EI != EE; ++EI) { ExplodedNode *N = const_cast<ExplodedNode*>(EI->begin()->getErrorNode()); if (N) Src.push_back(N); } ViewGraph(&Src[0], &Src[0]+Src.size()); } else { GraphPrintCheckerState = this; GraphPrintSourceManager = &getContext().getSourceManager(); llvm::ViewGraph(*G.roots_begin(), "ExprEngine"); GraphPrintCheckerState = NULL; GraphPrintSourceManager = NULL; } #endif } void ExprEngine::ViewGraph(ExplodedNode** Beg, ExplodedNode** End) { #ifndef NDEBUG GraphPrintCheckerState = this; GraphPrintSourceManager = &getContext().getSourceManager(); std::auto_ptr<ExplodedGraph> TrimmedG(G.Trim(Beg, End).first); if (!TrimmedG.get()) llvm::errs() << "warning: Trimmed ExplodedGraph is empty.\n"; else llvm::ViewGraph(*TrimmedG->roots_begin(), "TrimmedExprEngine"); GraphPrintCheckerState = NULL; GraphPrintSourceManager = NULL; #endif }