| //== Environment.cpp - Map from Stmt* to Locations/Values -------*- C++ -*--==// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defined the Environment and EnvironmentManager classes. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Analysis/AnalysisContext.h" |
| #include "clang/Analysis/CFG.h" |
| #include "clang/GR/PathSensitive/GRState.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| SVal Environment::lookupExpr(const Stmt* E) const { |
| const SVal* X = ExprBindings.lookup(E); |
| if (X) { |
| SVal V = *X; |
| return V; |
| } |
| return UnknownVal(); |
| } |
| |
| SVal Environment::getSVal(const Stmt *E, SValBuilder& svalBuilder) const { |
| for (;;) { |
| switch (E->getStmtClass()) { |
| case Stmt::AddrLabelExprClass: |
| return svalBuilder.makeLoc(cast<AddrLabelExpr>(E)); |
| case Stmt::ParenExprClass: |
| // ParenExprs are no-ops. |
| E = cast<ParenExpr>(E)->getSubExpr(); |
| continue; |
| case Stmt::CharacterLiteralClass: { |
| const CharacterLiteral* C = cast<CharacterLiteral>(E); |
| return svalBuilder.makeIntVal(C->getValue(), C->getType()); |
| } |
| case Stmt::CXXBoolLiteralExprClass: { |
| const SVal *X = ExprBindings.lookup(E); |
| if (X) |
| return *X; |
| else |
| return svalBuilder.makeIntVal(cast<CXXBoolLiteralExpr>(E)); |
| } |
| case Stmt::IntegerLiteralClass: { |
| // In C++, this expression may have been bound to a temporary object. |
| SVal const *X = ExprBindings.lookup(E); |
| if (X) |
| return *X; |
| else |
| return svalBuilder.makeIntVal(cast<IntegerLiteral>(E)); |
| } |
| case Stmt::ImplicitCastExprClass: |
| case Stmt::CStyleCastExprClass: { |
| // We blast through no-op casts to get the descendant |
| // subexpression that has a value. |
| const CastExpr* C = cast<CastExpr>(E); |
| QualType CT = C->getType(); |
| if (CT->isVoidType()) |
| return UnknownVal(); |
| if (C->getCastKind() == CK_NoOp) { |
| E = C->getSubExpr(); |
| continue; |
| } |
| break; |
| } |
| case Stmt::ExprWithCleanupsClass: |
| E = cast<ExprWithCleanups>(E)->getSubExpr(); |
| continue; |
| case Stmt::CXXBindTemporaryExprClass: |
| E = cast<CXXBindTemporaryExpr>(E)->getSubExpr(); |
| continue; |
| case Stmt::CXXFunctionalCastExprClass: |
| E = cast<CXXFunctionalCastExpr>(E)->getSubExpr(); |
| continue; |
| // Handle all other Stmt* using a lookup. |
| default: |
| break; |
| }; |
| break; |
| } |
| return lookupExpr(E); |
| } |
| |
| Environment EnvironmentManager::bindExpr(Environment Env, const Stmt *S, |
| SVal V, bool Invalidate) { |
| assert(S); |
| |
| if (V.isUnknown()) { |
| if (Invalidate) |
| return Environment(F.remove(Env.ExprBindings, S)); |
| else |
| return Env; |
| } |
| |
| return Environment(F.add(Env.ExprBindings, S, V)); |
| } |
| |
| static inline const Stmt *MakeLocation(const Stmt *S) { |
| return (const Stmt*) (((uintptr_t) S) | 0x1); |
| } |
| |
| Environment EnvironmentManager::bindExprAndLocation(Environment Env, |
| const Stmt *S, |
| SVal location, SVal V) { |
| return Environment(F.add(F.add(Env.ExprBindings, MakeLocation(S), location), |
| S, V)); |
| } |
| |
| namespace { |
| class MarkLiveCallback : public SymbolVisitor { |
| SymbolReaper &SymReaper; |
| public: |
| MarkLiveCallback(SymbolReaper &symreaper) : SymReaper(symreaper) {} |
| bool VisitSymbol(SymbolRef sym) { SymReaper.markLive(sym); return true; } |
| }; |
| } // end anonymous namespace |
| |
| static bool isBlockExprInCallers(const Stmt *E, const LocationContext *LC) { |
| const LocationContext *ParentLC = LC->getParent(); |
| while (ParentLC) { |
| CFG &C = *ParentLC->getCFG(); |
| if (C.isBlkExpr(E)) |
| return true; |
| ParentLC = ParentLC->getParent(); |
| } |
| |
| return false; |
| } |
| |
| // In addition to mapping from Stmt * - > SVals in the Environment, we also |
| // maintain a mapping from Stmt * -> SVals (locations) that were used during |
| // a load and store. |
| static inline bool IsLocation(const Stmt *S) { |
| return (bool) (((uintptr_t) S) & 0x1); |
| } |
| |
| // RemoveDeadBindings: |
| // - Remove subexpression bindings. |
| // - Remove dead block expression bindings. |
| // - Keep live block expression bindings: |
| // - Mark their reachable symbols live in SymbolReaper, |
| // see ScanReachableSymbols. |
| // - Mark the region in DRoots if the binding is a loc::MemRegionVal. |
| Environment |
| EnvironmentManager::RemoveDeadBindings(Environment Env, |
| SymbolReaper &SymReaper, |
| const GRState *ST, |
| llvm::SmallVectorImpl<const MemRegion*> &DRoots) { |
| |
| CFG &C = *SymReaper.getLocationContext()->getCFG(); |
| |
| // We construct a new Environment object entirely, as this is cheaper than |
| // individually removing all the subexpression bindings (which will greatly |
| // outnumber block-level expression bindings). |
| Environment NewEnv = getInitialEnvironment(); |
| |
| llvm::SmallVector<std::pair<const Stmt*, SVal>, 10> deferredLocations; |
| |
| // Iterate over the block-expr bindings. |
| for (Environment::iterator I = Env.begin(), E = Env.end(); |
| I != E; ++I) { |
| |
| const Stmt *BlkExpr = I.getKey(); |
| |
| // For recorded locations (used when evaluating loads and stores), we |
| // consider them live only when their associated normal expression is |
| // also live. |
| // NOTE: This assumes that loads/stores that evaluated to UnknownVal |
| // still have an entry in the map. |
| if (IsLocation(BlkExpr)) { |
| deferredLocations.push_back(std::make_pair(BlkExpr, I.getData())); |
| continue; |
| } |
| |
| const SVal &X = I.getData(); |
| |
| // Block-level expressions in callers are assumed always live. |
| if (isBlockExprInCallers(BlkExpr, SymReaper.getLocationContext())) { |
| NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, BlkExpr, X); |
| |
| if (isa<loc::MemRegionVal>(X)) { |
| const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion(); |
| DRoots.push_back(R); |
| } |
| |
| // Mark all symbols in the block expr's value live. |
| MarkLiveCallback cb(SymReaper); |
| ST->scanReachableSymbols(X, cb); |
| continue; |
| } |
| |
| // Not a block-level expression? |
| if (!C.isBlkExpr(BlkExpr)) |
| continue; |
| |
| if (SymReaper.isLive(BlkExpr)) { |
| // Copy the binding to the new map. |
| NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, BlkExpr, X); |
| |
| // If the block expr's value is a memory region, then mark that region. |
| if (isa<loc::MemRegionVal>(X)) { |
| const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion(); |
| DRoots.push_back(R); |
| } |
| |
| // Mark all symbols in the block expr's value live. |
| MarkLiveCallback cb(SymReaper); |
| ST->scanReachableSymbols(X, cb); |
| continue; |
| } |
| |
| // Otherwise the expression is dead with a couple exceptions. |
| // Do not misclean LogicalExpr or ConditionalOperator. It is dead at the |
| // beginning of itself, but we need its UndefinedVal to determine its |
| // SVal. |
| if (X.isUndef() && cast<UndefinedVal>(X).getData()) |
| NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, BlkExpr, X); |
| } |
| |
| // Go through he deferred locations and add them to the new environment if |
| // the correspond Stmt* is in the map as well. |
| for (llvm::SmallVectorImpl<std::pair<const Stmt*, SVal> >::iterator |
| I = deferredLocations.begin(), E = deferredLocations.end(); I != E; ++I) { |
| const Stmt *S = (Stmt*) (((uintptr_t) I->first) & (uintptr_t) ~0x1); |
| if (NewEnv.ExprBindings.lookup(S)) |
| NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, I->first, I->second); |
| } |
| |
| return NewEnv; |
| } |