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Diffstat (limited to 'lib/Analysis/RegionStore.cpp')
| -rw-r--r-- | lib/Analysis/RegionStore.cpp | 1304 |
1 files changed, 1304 insertions, 0 deletions
diff --git a/lib/Analysis/RegionStore.cpp b/lib/Analysis/RegionStore.cpp new file mode 100644 index 0000000..02d3d1f --- /dev/null +++ b/lib/Analysis/RegionStore.cpp @@ -0,0 +1,1304 @@ +//== RegionStore.cpp - Field-sensitive store model --------------*- 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 basic region store model. In this model, we do have field +// sensitivity. But we assume nothing about the heap shape. So recursive data +// structures are largely ignored. Basically we do 1-limiting analysis. +// Parameter pointers are assumed with no aliasing. Pointee objects of +// parameters are created lazily. +// +//===----------------------------------------------------------------------===// +#include "clang/Analysis/PathSensitive/MemRegion.h" +#include "clang/Analysis/PathSensitive/GRState.h" +#include "clang/Analysis/PathSensitive/GRStateTrait.h" +#include "clang/Analysis/Analyses/LiveVariables.h" +#include "clang/Basic/TargetInfo.h" + +#include "llvm/ADT/ImmutableMap.h" +#include "llvm/ADT/ImmutableList.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Support/Compiler.h" + +using namespace clang; + +// Actual Store type. +typedef llvm::ImmutableMap<const MemRegion*, SVal> RegionBindingsTy; + +//===----------------------------------------------------------------------===// +// Region "Views" +//===----------------------------------------------------------------------===// +// +// MemRegions can be layered on top of each other. This GDM entry tracks +// what are the MemRegions that layer a given MemRegion. +// +typedef llvm::ImmutableSet<const MemRegion*> RegionViews; +namespace { class VISIBILITY_HIDDEN RegionViewMap {}; } +static int RegionViewMapIndex = 0; +namespace clang { + template<> struct GRStateTrait<RegionViewMap> + : public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*, + RegionViews> > { + + static void* GDMIndex() { return &RegionViewMapIndex; } + }; +} + +// RegionCasts records the current cast type of a region. +namespace { class VISIBILITY_HIDDEN RegionCasts {}; } +static int RegionCastsIndex = 0; +namespace clang { + template<> struct GRStateTrait<RegionCasts> + : public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*, + QualType> > { + static void* GDMIndex() { return &RegionCastsIndex; } + }; +} + +//===----------------------------------------------------------------------===// +// Region "Extents" +//===----------------------------------------------------------------------===// +// +// MemRegions represent chunks of memory with a size (their "extent"). This +// GDM entry tracks the extents for regions. Extents are in bytes. +// +namespace { class VISIBILITY_HIDDEN RegionExtents {}; } +static int RegionExtentsIndex = 0; +namespace clang { + template<> struct GRStateTrait<RegionExtents> + : public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*, SVal> > { + static void* GDMIndex() { return &RegionExtentsIndex; } + }; +} + +//===----------------------------------------------------------------------===// +// Region "killsets". +//===----------------------------------------------------------------------===// +// +// RegionStore lazily adds value bindings to regions when the analyzer handles +// assignment statements. Killsets track which default values have been +// killed, thus distinguishing between "unknown" values and default +// values. Regions are added to killset only when they are assigned "unknown" +// directly, otherwise we should have their value in the region bindings. +// +namespace { class VISIBILITY_HIDDEN RegionKills {}; } +static int RegionKillsIndex = 0; +namespace clang { + template<> struct GRStateTrait<RegionKills> + : public GRStatePartialTrait< llvm::ImmutableSet<const MemRegion*> > { + static void* GDMIndex() { return &RegionKillsIndex; } + }; +} + +//===----------------------------------------------------------------------===// +// Regions with default values. +//===----------------------------------------------------------------------===// +// +// This GDM entry tracks what regions have a default value if they have no bound +// value and have not been killed. +// +namespace { class VISIBILITY_HIDDEN RegionDefaultValue {}; } +static int RegionDefaultValueIndex = 0; +namespace clang { + template<> struct GRStateTrait<RegionDefaultValue> + : public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*, SVal> > { + static void* GDMIndex() { return &RegionDefaultValueIndex; } + }; +} + +//===----------------------------------------------------------------------===// +// Main RegionStore logic. +//===----------------------------------------------------------------------===// + +namespace { + +class VISIBILITY_HIDDEN RegionStoreSubRegionMap : public SubRegionMap { + typedef llvm::DenseMap<const MemRegion*, + llvm::ImmutableSet<const MemRegion*> > Map; + + llvm::ImmutableSet<const MemRegion*>::Factory F; + Map M; + +public: + void add(const MemRegion* Parent, const MemRegion* SubRegion) { + Map::iterator I = M.find(Parent); + M.insert(std::make_pair(Parent, + F.Add(I == M.end() ? F.GetEmptySet() : I->second, SubRegion))); + } + + ~RegionStoreSubRegionMap() {} + + bool iterSubRegions(const MemRegion* Parent, Visitor& V) const { + Map::iterator I = M.find(Parent); + + if (I == M.end()) + return true; + + llvm::ImmutableSet<const MemRegion*> S = I->second; + for (llvm::ImmutableSet<const MemRegion*>::iterator SI=S.begin(),SE=S.end(); + SI != SE; ++SI) { + if (!V.Visit(Parent, *SI)) + return false; + } + + return true; + } +}; + +class VISIBILITY_HIDDEN RegionStoreManager : public StoreManager { + RegionBindingsTy::Factory RBFactory; + RegionViews::Factory RVFactory; + + const MemRegion* SelfRegion; + const ImplicitParamDecl *SelfDecl; + +public: + RegionStoreManager(GRStateManager& mgr) + : StoreManager(mgr), + RBFactory(mgr.getAllocator()), + RVFactory(mgr.getAllocator()), + SelfRegion(0), SelfDecl(0) { + if (const ObjCMethodDecl* MD = + dyn_cast<ObjCMethodDecl>(&StateMgr.getCodeDecl())) + SelfDecl = MD->getSelfDecl(); + } + + virtual ~RegionStoreManager() {} + + SubRegionMap* getSubRegionMap(const GRState *state); + + const GRState* BindCompoundLiteral(const GRState* St, + const CompoundLiteralExpr* CL, SVal V); + + /// getLValueString - Returns an SVal representing the lvalue of a + /// StringLiteral. Within RegionStore a StringLiteral has an + /// associated StringRegion, and the lvalue of a StringLiteral is + /// the lvalue of that region. + SVal getLValueString(const GRState* St, const StringLiteral* S); + + /// getLValueCompoundLiteral - Returns an SVal representing the + /// lvalue of a compound literal. Within RegionStore a compound + /// literal has an associated region, and the lvalue of the + /// compound literal is the lvalue of that region. + SVal getLValueCompoundLiteral(const GRState* St, const CompoundLiteralExpr*); + + /// getLValueVar - Returns an SVal that represents the lvalue of a + /// variable. Within RegionStore a variable has an associated + /// VarRegion, and the lvalue of the variable is the lvalue of that region. + SVal getLValueVar(const GRState* St, const VarDecl* VD); + + SVal getLValueIvar(const GRState* St, const ObjCIvarDecl* D, SVal Base); + + SVal getLValueField(const GRState* St, SVal Base, const FieldDecl* D); + + SVal getLValueFieldOrIvar(const GRState* St, SVal Base, const Decl* D); + + SVal getLValueElement(const GRState* St, QualType elementType, + SVal Base, SVal Offset); + + SVal getSizeInElements(const GRState* St, const MemRegion* R); + + /// ArrayToPointer - Emulates the "decay" of an array to a pointer + /// type. 'Array' represents the lvalue of the array being decayed + /// to a pointer, and the returned SVal represents the decayed + /// version of that lvalue (i.e., a pointer to the first element of + /// the array). This is called by GRExprEngine when evaluating + /// casts from arrays to pointers. + SVal ArrayToPointer(Loc Array); + + CastResult CastRegion(const GRState* state, const MemRegion* R, + QualType CastToTy); + + SVal EvalBinOp(const GRState *state,BinaryOperator::Opcode Op,Loc L,NonLoc R); + + /// The high level logic for this method is this: + /// Retrieve (L) + /// if L has binding + /// return L's binding + /// else if L is in killset + /// return unknown + /// else + /// if L is on stack or heap + /// return undefined + /// else + /// return symbolic + SVal Retrieve(const GRState* state, Loc L, QualType T = QualType()); + + const GRState* Bind(const GRState* St, Loc LV, SVal V); + + Store Remove(Store store, Loc LV); + + Store getInitialStore() { return RBFactory.GetEmptyMap().getRoot(); } + + /// getSelfRegion - Returns the region for the 'self' (Objective-C) or + /// 'this' object (C++). When used when analyzing a normal function this + /// method returns NULL. + const MemRegion* getSelfRegion(Store) { + if (!SelfDecl) + return 0; + + if (!SelfRegion) { + const ObjCMethodDecl *MD = cast<ObjCMethodDecl>(&StateMgr.getCodeDecl()); + SelfRegion = MRMgr.getObjCObjectRegion(MD->getClassInterface(), + MRMgr.getHeapRegion()); + } + + return SelfRegion; + } + + /// RemoveDeadBindings - Scans the RegionStore of 'state' for dead values. + /// It returns a new Store with these values removed, and populates LSymbols + // and DSymbols with the known set of live and dead symbols respectively. + Store RemoveDeadBindings(const GRState* state, Stmt* Loc, + SymbolReaper& SymReaper, + llvm::SmallVectorImpl<const MemRegion*>& RegionRoots); + + const GRState* BindDecl(const GRState* St, const VarDecl* VD, SVal InitVal); + + const GRState* BindDeclWithNoInit(const GRState* St, const VarDecl* VD) { + return St; + } + + const GRState* setExtent(const GRState* St, const MemRegion* R, SVal Extent); + const GRState* setCastType(const GRState* St, const MemRegion* R, QualType T); + + static inline RegionBindingsTy GetRegionBindings(Store store) { + return RegionBindingsTy(static_cast<const RegionBindingsTy::TreeTy*>(store)); + } + + void print(Store store, std::ostream& Out, const char* nl, const char *sep); + + void iterBindings(Store store, BindingsHandler& f) { + // FIXME: Implement. + } + const GRState* setDefaultValue(const GRState* St, const MemRegion* R, SVal V); +private: + const GRState* BindArray(const GRState* St, const TypedRegion* R, SVal V); + + /// Retrieve the values in a struct and return a CompoundVal, used when doing + /// struct copy: + /// struct s x, y; + /// x = y; + /// y's value is retrieved by this method. + SVal RetrieveStruct(const GRState* St, const TypedRegion* R); + + SVal RetrieveArray(const GRState* St, const TypedRegion* R); + + const GRState* BindStruct(const GRState* St, const TypedRegion* R, SVal V); + + /// KillStruct - Set the entire struct to unknown. + const GRState* KillStruct(const GRState* St, const TypedRegion* R); + + // Utility methods. + BasicValueFactory& getBasicVals() { return StateMgr.getBasicVals(); } + ASTContext& getContext() { return StateMgr.getContext(); } + + SymbolManager& getSymbolManager() { return StateMgr.getSymbolManager(); } + + const GRState* AddRegionView(const GRState* St, + const MemRegion* View, const MemRegion* Base); + const GRState* RemoveRegionView(const GRState* St, + const MemRegion* View, const MemRegion* Base); +}; + +} // end anonymous namespace + +StoreManager* clang::CreateRegionStoreManager(GRStateManager& StMgr) { + return new RegionStoreManager(StMgr); +} + +SubRegionMap* RegionStoreManager::getSubRegionMap(const GRState *state) { + RegionBindingsTy B = GetRegionBindings(state->getStore()); + RegionStoreSubRegionMap *M = new RegionStoreSubRegionMap(); + + for (RegionBindingsTy::iterator I=B.begin(), E=B.end(); I!=E; ++I) { + if (const SubRegion* R = dyn_cast<SubRegion>(I.getKey())) + M->add(R->getSuperRegion(), R); + } + + return M; +} + +/// getLValueString - Returns an SVal representing the lvalue of a +/// StringLiteral. Within RegionStore a StringLiteral has an +/// associated StringRegion, and the lvalue of a StringLiteral is the +/// lvalue of that region. +SVal RegionStoreManager::getLValueString(const GRState* St, + const StringLiteral* S) { + return loc::MemRegionVal(MRMgr.getStringRegion(S)); +} + +/// getLValueVar - Returns an SVal that represents the lvalue of a +/// variable. Within RegionStore a variable has an associated +/// VarRegion, and the lvalue of the variable is the lvalue of that region. +SVal RegionStoreManager::getLValueVar(const GRState* St, const VarDecl* VD) { + return loc::MemRegionVal(MRMgr.getVarRegion(VD)); +} + +/// getLValueCompoundLiteral - Returns an SVal representing the lvalue +/// of a compound literal. Within RegionStore a compound literal +/// has an associated region, and the lvalue of the compound literal +/// is the lvalue of that region. +SVal +RegionStoreManager::getLValueCompoundLiteral(const GRState* St, + const CompoundLiteralExpr* CL) { + return loc::MemRegionVal(MRMgr.getCompoundLiteralRegion(CL)); +} + +SVal RegionStoreManager::getLValueIvar(const GRState* St, const ObjCIvarDecl* D, + SVal Base) { + return getLValueFieldOrIvar(St, Base, D); +} + +SVal RegionStoreManager::getLValueField(const GRState* St, SVal Base, + const FieldDecl* D) { + return getLValueFieldOrIvar(St, Base, D); +} + +SVal RegionStoreManager::getLValueFieldOrIvar(const GRState* St, SVal Base, + const Decl* D) { + if (Base.isUnknownOrUndef()) + return Base; + + Loc BaseL = cast<Loc>(Base); + const MemRegion* BaseR = 0; + + switch (BaseL.getSubKind()) { + case loc::MemRegionKind: + BaseR = cast<loc::MemRegionVal>(BaseL).getRegion(); + break; + + case loc::GotoLabelKind: + // These are anormal cases. Flag an undefined value. + return UndefinedVal(); + + case loc::ConcreteIntKind: + // While these seem funny, this can happen through casts. + // FIXME: What we should return is the field offset. For example, + // add the field offset to the integer value. That way funny things + // like this work properly: &(((struct foo *) 0xa)->f) + return Base; + + default: + assert(0 && "Unhandled Base."); + return Base; + } + + // NOTE: We must have this check first because ObjCIvarDecl is a subclass + // of FieldDecl. + if (const ObjCIvarDecl *ID = dyn_cast<ObjCIvarDecl>(D)) + return loc::MemRegionVal(MRMgr.getObjCIvarRegion(ID, BaseR)); + + return loc::MemRegionVal(MRMgr.getFieldRegion(cast<FieldDecl>(D), BaseR)); +} + +SVal RegionStoreManager::getLValueElement(const GRState* St, + QualType elementType, + SVal Base, SVal Offset) { + + // If the base is an unknown or undefined value, just return it back. + // FIXME: For absolute pointer addresses, we just return that value back as + // well, although in reality we should return the offset added to that + // value. + if (Base.isUnknownOrUndef() || isa<loc::ConcreteInt>(Base)) + return Base; + + // Only handle integer offsets... for now. + if (!isa<nonloc::ConcreteInt>(Offset)) + return UnknownVal(); + + const MemRegion* BaseRegion = cast<loc::MemRegionVal>(Base).getRegion(); + + // Pointer of any type can be cast and used as array base. + const ElementRegion *ElemR = dyn_cast<ElementRegion>(BaseRegion); + + if (!ElemR) { + // + // If the base region is not an ElementRegion, create one. + // This can happen in the following example: + // + // char *p = __builtin_alloc(10); + // p[1] = 8; + // + // Observe that 'p' binds to an AllocaRegion. + // + + // Offset might be unsigned. We have to convert it to signed ConcreteInt. + if (nonloc::ConcreteInt* CI = dyn_cast<nonloc::ConcreteInt>(&Offset)) { + const llvm::APSInt& OffI = CI->getValue(); + if (OffI.isUnsigned()) { + llvm::APSInt Tmp = OffI; + Tmp.setIsSigned(true); + Offset = NonLoc::MakeVal(getBasicVals(), Tmp); + } + } + return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset, + BaseRegion)); + } + + SVal BaseIdx = ElemR->getIndex(); + + if (!isa<nonloc::ConcreteInt>(BaseIdx)) + return UnknownVal(); + + const llvm::APSInt& BaseIdxI = cast<nonloc::ConcreteInt>(BaseIdx).getValue(); + const llvm::APSInt& OffI = cast<nonloc::ConcreteInt>(Offset).getValue(); + assert(BaseIdxI.isSigned()); + + // FIXME: This appears to be the assumption of this code. We should review + // whether or not BaseIdxI.getBitWidth() < OffI.getBitWidth(). If it + // can't we need to put a comment here. If it can, we should handle it. + assert(BaseIdxI.getBitWidth() >= OffI.getBitWidth()); + + const MemRegion *ArrayR = ElemR->getSuperRegion(); + SVal NewIdx; + + if (OffI.isUnsigned() || OffI.getBitWidth() < BaseIdxI.getBitWidth()) { + // 'Offset' might be unsigned. We have to convert it to signed and + // possibly extend it. + llvm::APSInt Tmp = OffI; + + if (OffI.getBitWidth() < BaseIdxI.getBitWidth()) + Tmp.extend(BaseIdxI.getBitWidth()); + + Tmp.setIsSigned(true); + Tmp += BaseIdxI; // Compute the new offset. + NewIdx = NonLoc::MakeVal(getBasicVals(), Tmp); + } + else + NewIdx = nonloc::ConcreteInt(getBasicVals().getValue(BaseIdxI + OffI)); + + return loc::MemRegionVal(MRMgr.getElementRegion(elementType, NewIdx, ArrayR)); +} + +SVal RegionStoreManager::getSizeInElements(const GRState* St, + const MemRegion* R) { + if (const VarRegion* VR = dyn_cast<VarRegion>(R)) { + // Get the type of the variable. + QualType T = VR->getDesugaredValueType(getContext()); + + // FIXME: Handle variable-length arrays. + if (isa<VariableArrayType>(T)) + return UnknownVal(); + + if (const ConstantArrayType* CAT = dyn_cast<ConstantArrayType>(T)) { + // return the size as signed integer. + return NonLoc::MakeVal(getBasicVals(), CAT->getSize(), false); + } + + GRStateRef state(St, StateMgr); + const QualType* CastTy = state.get<RegionCasts>(VR); + + // If the VarRegion is cast to other type, compute the size with respect to + // that type. + if (CastTy) { + QualType EleTy =cast<PointerType>(CastTy->getTypePtr())->getPointeeType(); + QualType VarTy = VR->getValueType(getContext()); + uint64_t EleSize = getContext().getTypeSize(EleTy); + uint64_t VarSize = getContext().getTypeSize(VarTy); + return NonLoc::MakeIntVal(getBasicVals(), VarSize / EleSize, false); + } + + // Clients can use ordinary variables as if they were arrays. These + // essentially are arrays of size 1. + return NonLoc::MakeIntVal(getBasicVals(), 1, false); + } + + if (const StringRegion* SR = dyn_cast<StringRegion>(R)) { + const StringLiteral* Str = SR->getStringLiteral(); + // We intentionally made the size value signed because it participates in + // operations with signed indices. + return NonLoc::MakeIntVal(getBasicVals(), Str->getByteLength()+1, false); + } + + if (const FieldRegion* FR = dyn_cast<FieldRegion>(R)) { + // FIXME: Unsupported yet. + FR = 0; + return UnknownVal(); + } + + if (isa<SymbolicRegion>(R)) { + return UnknownVal(); + } + + if (isa<AllocaRegion>(R)) { + return UnknownVal(); + } + + if (isa<ElementRegion>(R)) { + return UnknownVal(); + } + + assert(0 && "Other regions are not supported yet."); + return UnknownVal(); +} + +/// ArrayToPointer - Emulates the "decay" of an array to a pointer +/// type. 'Array' represents the lvalue of the array being decayed +/// to a pointer, and the returned SVal represents the decayed +/// version of that lvalue (i.e., a pointer to the first element of +/// the array). This is called by GRExprEngine when evaluating casts +/// from arrays to pointers. +SVal RegionStoreManager::ArrayToPointer(Loc Array) { + if (!isa<loc::MemRegionVal>(Array)) + return UnknownVal(); + + const MemRegion* R = cast<loc::MemRegionVal>(&Array)->getRegion(); + const TypedRegion* ArrayR = dyn_cast<TypedRegion>(R); + + if (!ArrayR) + return UnknownVal(); + + // Strip off typedefs from the ArrayRegion's ValueType. + QualType T = ArrayR->getValueType(getContext())->getDesugaredType(); + ArrayType *AT = cast<ArrayType>(T); + T = AT->getElementType(); + + nonloc::ConcreteInt Idx(getBasicVals().getZeroWithPtrWidth(false)); + ElementRegion* ER = MRMgr.getElementRegion(T, Idx, ArrayR); + + return loc::MemRegionVal(ER); +} + +RegionStoreManager::CastResult +RegionStoreManager::CastRegion(const GRState* state, const MemRegion* R, + QualType CastToTy) { + + ASTContext& Ctx = StateMgr.getContext(); + + // We need to know the real type of CastToTy. + QualType ToTy = Ctx.getCanonicalType(CastToTy); + + // Check cast to ObjCQualifiedID type. + if (isa<ObjCQualifiedIdType>(ToTy)) { + // FIXME: Record the type information aside. + return CastResult(state, R); + } + + // CodeTextRegion should be cast to only function pointer type. + if (isa<CodeTextRegion>(R)) { + assert(CastToTy->isFunctionPointerType() || CastToTy->isBlockPointerType()); + return CastResult(state, R); + } + + // Now assume we are casting from pointer to pointer. Other cases should + // already be handled. + QualType PointeeTy = cast<PointerType>(ToTy.getTypePtr())->getPointeeType(); + + // Process region cast according to the kind of the region being cast. + + // FIXME: Need to handle arbitrary downcasts. + if (isa<SymbolicRegion>(R) || isa<AllocaRegion>(R)) { + state = setCastType(state, R, ToTy); + return CastResult(state, R); + } + + // VarRegion, ElementRegion, and FieldRegion has an inherent type. Normally + // they should not be cast. We only layer an ElementRegion when the cast-to + // pointee type is of smaller size. In other cases, we return the original + // VarRegion. + if (isa<VarRegion>(R) || isa<ElementRegion>(R) || isa<FieldRegion>(R) + || isa<ObjCIvarRegion>(R) || isa<CompoundLiteralRegion>(R)) { + // If the pointee type is incomplete, do not compute its size, and return + // the original region. + if (const RecordType *RT = dyn_cast<RecordType>(PointeeTy.getTypePtr())) { + const RecordDecl *D = RT->getDecl(); + if (!D->getDefinition(getContext())) + return CastResult(state, R); + } + + QualType ObjTy = cast<TypedRegion>(R)->getValueType(getContext()); + uint64_t PointeeTySize = getContext().getTypeSize(PointeeTy); + uint64_t ObjTySize = getContext().getTypeSize(ObjTy); + + if ((PointeeTySize > 0 && PointeeTySize < ObjTySize) || + (ObjTy->isAggregateType() && PointeeTy->isScalarType())) { + // Record the cast type of the region. + state = setCastType(state, R, ToTy); + + SVal Idx = ValMgr.makeZeroArrayIndex(); + ElementRegion* ER = MRMgr.getElementRegion(PointeeTy, Idx, R); + return CastResult(state, ER); + } else + return CastResult(state, R); + } + + if (isa<ObjCObjectRegion>(R)) { + return CastResult(state, R); + } + + assert(0 && "Unprocessed region."); + return 0; +} + +SVal RegionStoreManager::EvalBinOp(const GRState *state, + BinaryOperator::Opcode Op, Loc L, NonLoc R) { + // Assume the base location is MemRegionVal. + if (!isa<loc::MemRegionVal>(L)) + return UnknownVal(); + + const MemRegion* MR = cast<loc::MemRegionVal>(L).getRegion(); + const ElementRegion *ER = 0; + + // If the operand is a symbolic or alloca region, create the first element + // region on it. + if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR)) { + // Get symbol's type. It should be a pointer type. + SymbolRef Sym = SR->getSymbol(); + QualType T = Sym->getType(getContext()); + QualType EleTy = cast<PointerType>(T.getTypePtr())->getPointeeType(); + + SVal ZeroIdx = ValMgr.makeZeroArrayIndex(); + ER = MRMgr.getElementRegion(EleTy, ZeroIdx, SR); + } + else if (const AllocaRegion *AR = dyn_cast<AllocaRegion>(MR)) { + // Get the alloca region's current cast type. + GRStateRef StRef(state, StateMgr); + + GRStateTrait<RegionCasts>::lookup_type T = StRef.get<RegionCasts>(AR); + assert(T && "alloca region has no type."); + QualType EleTy = cast<PointerType>(T->getTypePtr())->getPointeeType(); + SVal ZeroIdx = ValMgr.makeZeroArrayIndex(); + ER = MRMgr.getElementRegion(EleTy, ZeroIdx, AR); + } + else + ER = cast<ElementRegion>(MR); + + SVal Idx = ER->getIndex(); + + nonloc::ConcreteInt* Base = dyn_cast<nonloc::ConcreteInt>(&Idx); + nonloc::ConcreteInt* Offset = dyn_cast<nonloc::ConcreteInt>(&R); + + // Only support concrete integer indexes for now. + if (Base && Offset) { + // FIXME: For now, convert the signedness and bitwidth of offset in case + // they don't match. This can result from pointer arithmetic. In reality, + // we should figure out what are the proper semantics and implement them. + // + // This addresses the test case test/Analysis/ptr-arith.c + // + nonloc::ConcreteInt OffConverted(getBasicVals().Convert(Base->getValue(), + Offset->getValue())); + SVal NewIdx = Base->EvalBinOp(getBasicVals(), Op, OffConverted); + const MemRegion* NewER = + MRMgr.getElementRegion(ER->getElementType(), NewIdx,ER->getSuperRegion()); + return Loc::MakeVal(NewER); + + } + + return UnknownVal(); +} + +SVal RegionStoreManager::Retrieve(const GRState* St, Loc L, QualType T) { + assert(!isa<UnknownVal>(L) && "location unknown"); + assert(!isa<UndefinedVal>(L) && "location undefined"); + + // FIXME: Is this even possible? Shouldn't this be treated as a null + // dereference at a higher level? + if (isa<loc::ConcreteInt>(L)) + return UndefinedVal(); + + const MemRegion* MR = cast<loc::MemRegionVal>(L).getRegion(); + + // FIXME: return symbolic value for these cases. + // Example: + // void f(int* p) { int x = *p; } + // char* p = alloca(); + // read(p); + // c = *p; + if (isa<SymbolicRegion>(MR) || isa<AllocaRegion>(MR)) + return UnknownVal(); + + // FIXME: Perhaps this method should just take a 'const MemRegion*' argument + // instead of 'Loc', and have the other Loc cases handled at a higher level. + const TypedRegion* R = cast<TypedRegion>(MR); + assert(R && "bad region"); + + // FIXME: We should eventually handle funny addressing. e.g.: + // + // int x = ...; + // int *p = &x; + // char *q = (char*) p; + // char c = *q; // returns the first byte of 'x'. + // + // Such funny addressing will occur due to layering of regions. + + QualType RTy = R->getValueType(getContext()); + + if (RTy->isStructureType()) + return RetrieveStruct(St, R); + + if (RTy->isArrayType()) + return RetrieveArray(St, R); + + // FIXME: handle Vector types. + if (RTy->isVectorType()) + return UnknownVal(); + + RegionBindingsTy B = GetRegionBindings(St->getStore()); + RegionBindingsTy::data_type* V = B.lookup(R); + + // Check if the region has a binding. + if (V) + return *V; + + GRStateRef state(St, StateMgr); + + // Check if the region is in killset. + if (state.contains<RegionKills>(R)) + return UnknownVal(); + + // Check if the region is an element region of a string literal. + if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) { + if (const StringRegion *StrR=dyn_cast<StringRegion>(ER->getSuperRegion())) { + const StringLiteral *Str = StrR->getStringLiteral(); + SVal Idx = ER->getIndex(); + if (nonloc::ConcreteInt *CI = dyn_cast<nonloc::ConcreteInt>(&Idx)) { + int64_t i = CI->getValue().getSExtValue(); + char c; + if (i == Str->getByteLength()) + c = '\0'; + else + c = Str->getStrData()[i]; + const llvm::APSInt &V = getBasicVals().getValue(c, getContext().CharTy); + return nonloc::ConcreteInt(V); + } + } + } + + // If the region is an element or field, it may have a default value. + if (isa<ElementRegion>(R) || isa<FieldRegion>(R)) { + const MemRegion* SuperR = cast<SubRegion>(R)->getSuperRegion(); + GRStateTrait<RegionDefaultValue>::lookup_type D = + state.get<RegionDefaultValue>(SuperR); + if (D) { + // If the default value is symbolic, we need to create a new symbol. + if (D->hasConjuredSymbol()) + return ValMgr.getRegionValueSymbolVal(R); + else + return *D; + } + } + + if (const ObjCIvarRegion *IVR = dyn_cast<ObjCIvarRegion>(R)) { + const MemRegion *SR = IVR->getSuperRegion(); + + // If the super region is 'self' then return the symbol representing + // the value of the ivar upon entry to the method. + if (SR == SelfRegion) { + // FIXME: Do we need to handle the case where the super region + // has a view? We want to canonicalize the bindings. + return ValMgr.getRegionValueSymbolVal(R); + } + + // Otherwise, we need a new symbol. For now return Unknown. + return UnknownVal(); + } + + // The location does not have a bound value. This means that it has + // the value it had upon its creation and/or entry to the analyzed + // function/method. These are either symbolic values or 'undefined'. + + // We treat function parameters as symbolic values. + if (const VarRegion* VR = dyn_cast<VarRegion>(R)) { + const VarDecl *VD = VR->getDecl(); + + if (VD == SelfDecl) + return loc::MemRegionVal(getSelfRegion(0)); + + if (isa<ParmVarDecl>(VD) || isa<ImplicitParamDecl>(VD) || + VD->hasGlobalStorage()) { + QualType VTy = VD->getType(); + if (Loc::IsLocType(VTy) || VTy->isIntegerType()) + return ValMgr.getRegionValueSymbolVal(VR); + else + return UnknownVal(); + } + } + + if (MRMgr.onStack(R) || MRMgr.onHeap(R)) { + // All stack variables are considered to have undefined values + // upon creation. All heap allocated blocks are considered to + // have undefined values as well unless they are explicitly bound + // to specific values. + return UndefinedVal(); + } + + // All other integer values are symbolic. + if (Loc::IsLocType(RTy) || RTy->isIntegerType()) + return ValMgr.getRegionValueSymbolVal(R); + else + return UnknownVal(); +} + +SVal RegionStoreManager::RetrieveStruct(const GRState* St,const TypedRegion* R){ + QualType T = R->getValueType(getContext()); + assert(T->isStructureType()); + + const RecordType* RT = cast<RecordType>(T.getTypePtr()); + RecordDecl* RD = RT->getDecl(); + assert(RD->isDefinition()); + + llvm::ImmutableList<SVal> StructVal = getBasicVals().getEmptySValList(); + + std::vector<FieldDecl *> Fields(RD->field_begin(getContext()), + RD->field_end(getContext())); + + for (std::vector<FieldDecl *>::reverse_iterator Field = Fields.rbegin(), + FieldEnd = Fields.rend(); + Field != FieldEnd; ++Field) { + FieldRegion* FR = MRMgr.getFieldRegion(*Field, R); + QualType FTy = (*Field)->getType(); + SVal FieldValue = Retrieve(St, loc::MemRegionVal(FR), FTy); + StructVal = getBasicVals().consVals(FieldValue, StructVal); + } + + return NonLoc::MakeCompoundVal(T, StructVal, getBasicVals()); +} + +SVal RegionStoreManager::RetrieveArray(const GRState* St, const TypedRegion* R){ + QualType T = R->getValueType(getContext()); + ConstantArrayType* CAT = cast<ConstantArrayType>(T.getTypePtr()); + + llvm::ImmutableList<SVal> ArrayVal = getBasicVals().getEmptySValList(); + llvm::APSInt Size(CAT->getSize(), false); + llvm::APSInt i = getBasicVals().getZeroWithPtrWidth(false); + + for (; i < Size; ++i) { + SVal Idx = NonLoc::MakeVal(getBasicVals(), i); + ElementRegion* ER = MRMgr.getElementRegion(CAT->getElementType(), Idx, R); + QualType ETy = ER->getElementType(); + SVal ElementVal = Retrieve(St, loc::MemRegionVal(ER), ETy); + ArrayVal = getBasicVals().consVals(ElementVal, ArrayVal); + } + + return NonLoc::MakeCompoundVal(T, ArrayVal, getBasicVals()); +} + +const GRState* RegionStoreManager::Bind(const GRState* St, Loc L, SVal V) { + // If we get here, the location should be a region. + const MemRegion* R = cast<loc::MemRegionVal>(L).getRegion(); + assert(R); + + // Check if the region is a struct region. + if (const TypedRegion* TR = dyn_cast<TypedRegion>(R)) + if (TR->getValueType(getContext())->isStructureType()) + return BindStruct(St, TR, V); + + Store store = St->getStore(); + RegionBindingsTy B = GetRegionBindings(store); + + if (V.isUnknown()) { + // Remove the binding. + store = RBFactory.Remove(B, R).getRoot(); + + // Add the region to the killset. + GRStateRef state(St, StateMgr); + St = state.add<RegionKills>(R); + } + else + store = RBFactory.Add(B, R, V).getRoot(); + + return StateMgr.MakeStateWithStore(St, store); +} + +Store RegionStoreManager::Remove(Store store, Loc L) { + const MemRegion* R = 0; + + if (isa<loc::MemRegionVal>(L)) + R = cast<loc::MemRegionVal>(L).getRegion(); + + if (R) { + RegionBindingsTy B = GetRegionBindings(store); + return RBFactory.Remove(B, R).getRoot(); + } + + return store; +} + +const GRState* RegionStoreManager::BindDecl(const GRState* St, + const VarDecl* VD, SVal InitVal) { + + QualType T = VD->getType(); + VarRegion* VR = MRMgr.getVarRegion(VD); + + if (T->isArrayType()) + return BindArray(St, VR, InitVal); + if (T->isStructureType()) + return BindStruct(St, VR, InitVal); + + return Bind(St, Loc::MakeVal(VR), InitVal); +} + +// FIXME: this method should be merged into Bind(). +const GRState* +RegionStoreManager::BindCompoundLiteral(const GRState* St, + const CompoundLiteralExpr* CL, SVal V) { + CompoundLiteralRegion* R = MRMgr.getCompoundLiteralRegion(CL); + return Bind(St, loc::MemRegionVal(R), V); +} + +const GRState* RegionStoreManager::setExtent(const GRState* St, + const MemRegion* R, SVal Extent) { + GRStateRef state(St, StateMgr); + return state.set<RegionExtents>(R, Extent); +} + + +static void UpdateLiveSymbols(SVal X, SymbolReaper& SymReaper) { + if (loc::MemRegionVal *XR = dyn_cast<loc::MemRegionVal>(&X)) { + const MemRegion *R = XR->getRegion(); + + while (R) { + if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R)) { + SymReaper.markLive(SR->getSymbol()); + return; + } + + if (const SubRegion *SR = dyn_cast<SubRegion>(R)) { + R = SR->getSuperRegion(); + continue; + } + + break; + } + + return; + } + + for (SVal::symbol_iterator SI=X.symbol_begin(), SE=X.symbol_end();SI!=SE;++SI) + SymReaper.markLive(*SI); +} + +Store RegionStoreManager::RemoveDeadBindings(const GRState* state, Stmt* Loc, + SymbolReaper& SymReaper, + llvm::SmallVectorImpl<const MemRegion*>& RegionRoots) +{ + + Store store = state->getStore(); + RegionBindingsTy B = GetRegionBindings(store); + + // Lazily constructed backmap from MemRegions to SubRegions. + typedef llvm::ImmutableSet<const MemRegion*> SubRegionsTy; + typedef llvm::ImmutableMap<const MemRegion*, SubRegionsTy> SubRegionsMapTy; + + // FIXME: As a future optimization we can modifiy BumpPtrAllocator to have + // the ability to reuse memory. This way we can keep TmpAlloc around as + // an instance variable of RegionStoreManager (avoiding repeated malloc + // overhead). + llvm::BumpPtrAllocator TmpAlloc; + + // Factory objects. + SubRegionsMapTy::Factory SubRegMapF(TmpAlloc); + SubRegionsTy::Factory SubRegF(TmpAlloc); + + // The backmap from regions to subregions. + SubRegionsMapTy SubRegMap = SubRegMapF.GetEmptyMap(); + + // Do a pass over the regions in the store. For VarRegions we check if + // the variable is still live and if so add it to the list of live roots. + // For other regions we populate our region backmap. + + llvm::SmallVector<const MemRegion*, 10> IntermediateRoots; + + for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) { + IntermediateRoots.push_back(I.getKey()); + } + + while (!IntermediateRoots.empty()) { + const MemRegion* R = IntermediateRoots.back(); + IntermediateRoots.pop_back(); + + if (const VarRegion* VR = dyn_cast<VarRegion>(R)) { + if (SymReaper.isLive(Loc, VR->getDecl())) + RegionRoots.push_back(VR); // This is a live "root". + } + else if (const SymbolicRegion* SR = dyn_cast<SymbolicRegion>(R)) { + if (SymReaper.isLive(SR->getSymbol())) + RegionRoots.push_back(SR); + } + else { + // Get the super region for R. + const MemRegion* SuperR = cast<SubRegion>(R)->getSuperRegion(); + + // Get the current set of subregions for SuperR. + const SubRegionsTy* SRptr = SubRegMap.lookup(SuperR); + SubRegionsTy SRs = SRptr ? *SRptr : SubRegF.GetEmptySet(); + + // Add R to the subregions of SuperR. + SubRegMap = SubRegMapF.Add(SubRegMap, SuperR, SubRegF.Add(SRs, R)); + + // Super region may be VarRegion or subregion of another VarRegion. Add it + // to the work list. + if (isa<SubRegion>(SuperR)) + IntermediateRoots.push_back(SuperR); + } + } + + // Process the worklist of RegionRoots. This performs a "mark-and-sweep" + // of the store. We want to find all live symbols and dead regions. + llvm::SmallPtrSet<const MemRegion*, 10> Marked; + + while (!RegionRoots.empty()) { + // Dequeue the next region on the worklist. + const MemRegion* R = RegionRoots.back(); + RegionRoots.pop_back(); + + // Check if we have already processed this region. + if (Marked.count(R)) continue; + + // Mark this region as processed. This is needed for termination in case + // a region is referenced more than once. + Marked.insert(R); + + // Mark the symbol for any live SymbolicRegion as "live". This means we + // should continue to track that symbol. + if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(R)) + SymReaper.markLive(SymR->getSymbol()); + + // Get the data binding for R (if any). + RegionBindingsTy::data_type* Xptr = B.lookup(R); + if (Xptr) { + SVal X = *Xptr; + UpdateLiveSymbols(X, SymReaper); // Update the set of live symbols. + + // If X is a region, then add it the RegionRoots. + if (loc::MemRegionVal* RegionX = dyn_cast<loc::MemRegionVal>(&X)) + RegionRoots.push_back(RegionX->getRegion()); + } + + // Get the subregions of R. These are RegionRoots as well since they + // represent values that are also bound to R. + const SubRegionsTy* SRptr = SubRegMap.lookup(R); + if (!SRptr) continue; + SubRegionsTy SR = *SRptr; + + for (SubRegionsTy::iterator I=SR.begin(), E=SR.end(); I!=E; ++I) + RegionRoots.push_back(*I); + } + + // We have now scanned the store, marking reachable regions and symbols + // as live. We now remove all the regions that are dead from the store + // as well as update DSymbols with the set symbols that are now dead. + for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) { + const MemRegion* R = I.getKey(); + + // If this region live? Is so, none of its symbols are dead. + if (Marked.count(R)) + continue; + + // Remove this dead region from the store. + store = Remove(store, Loc::MakeVal(R)); + + // Mark all non-live symbols that this region references as dead. + if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(R)) + SymReaper.maybeDead(SymR->getSymbol()); + + SVal X = I.getData(); + SVal::symbol_iterator SI = X.symbol_begin(), SE = X.symbol_end(); + for (; SI != SE; ++SI) SymReaper.maybeDead(*SI); + } + + return store; +} + +void RegionStoreManager::print(Store store, std::ostream& Out, + const char* nl, const char *sep) { + llvm::raw_os_ostream OS(Out); + RegionBindingsTy B = GetRegionBindings(store); + OS << "Store:" << nl; + + for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) { + OS << ' '; I.getKey()->print(OS); OS << " : "; + I.getData().print(OS); OS << nl; + } +} + +const GRState* RegionStoreManager::BindArray(const GRState* St, + const TypedRegion* R, SVal Init) { + QualType T = R->getValueType(getContext()); + assert(T->isArrayType()); + + // When we are binding the whole array, it always has default value 0. + GRStateRef state(St, StateMgr); + St = state.set<RegionDefaultValue>(R, NonLoc::MakeIntVal(getBasicVals(), 0, + false)); + + ConstantArrayType* CAT = cast<ConstantArrayType>(T.getTypePtr()); + + llvm::APSInt Size(CAT->getSize(), false); + llvm::APSInt i = getBasicVals().getValue(0, Size.getBitWidth(), + Size.isUnsigned()); + + // Check if the init expr is a StringLiteral. + if (isa<loc::MemRegionVal>(Init)) { + const MemRegion* InitR = cast<loc::MemRegionVal>(Init).getRegion(); + const StringLiteral* S = cast<StringRegion>(InitR)->getStringLiteral(); + const char* str = S->getStrData(); + unsigned len = S->getByteLength(); + unsigned j = 0; + + // Copy bytes from the string literal into the target array. Trailing bytes + // in the array that are not covered by the string literal are initialized + // to zero. + for (; i < Size; ++i, ++j) { + if (j >= len) + break; + + SVal Idx = NonLoc::MakeVal(getBasicVals(), i); + ElementRegion* ER = + MRMgr.getElementRegion(cast<ArrayType>(T)->getElementType(), + Idx, R); + + SVal V = NonLoc::MakeVal(getBasicVals(), str[j], sizeof(char)*8, true); + St = Bind(St, loc::MemRegionVal(ER), V); + } + + return St; + } + + nonloc::CompoundVal& CV = cast<nonloc::CompoundVal>(Init); + nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end(); + + for (; i < Size; ++i, ++VI) { + // The init list might be shorter than the array decl. + if (VI == VE) + break; + + SVal Idx = NonLoc::MakeVal(getBasicVals(), i); + ElementRegion* ER = + MRMgr.getElementRegion(cast<ArrayType>(T)->getElementType(), + Idx, R); + + if (CAT->getElementType()->isStructureType()) + St = BindStruct(St, ER, *VI); + else + St = Bind(St, Loc::MakeVal(ER), *VI); + } + + return St; +} + +const GRState* +RegionStoreManager::BindStruct(const GRState* St, const TypedRegion* R, SVal V){ + QualType T = R->getValueType(getContext()); + assert(T->isStructureType()); + + const RecordType* RT = T->getAsRecordType(); + RecordDecl* RD = RT->getDecl(); + + if (!RD->isDefinition()) + return St; + + if (V.isUnknown()) + return KillStruct(St, R); + + nonloc::CompoundVal& CV = cast<nonloc::CompoundVal>(V); + nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end(); + RecordDecl::field_iterator FI = RD->field_begin(getContext()), + FE = RD->field_end(getContext()); + + for (; FI != FE; ++FI, ++VI) { + + // There may be fewer values than fields only when we are initializing a + // struct decl. In this case, mark the region as having default value. + if (VI == VE) { + GRStateRef state(St, StateMgr); + const NonLoc& Idx = NonLoc::MakeIntVal(getBasicVals(), 0, false); + St = state.set<RegionDefaultValue>(R, Idx); + break; + } + + QualType FTy = (*FI)->getType(); + FieldRegion* FR = MRMgr.getFieldRegion(*FI, R); + + if (Loc::IsLocType(FTy) || FTy->isIntegerType()) + St = Bind(St, Loc::MakeVal(FR), *VI); + + else if (FTy->isArrayType()) + St = BindArray(St, FR, *VI); + + else if (FTy->isStructureType()) + St = BindStruct(St, FR, *VI); + } + + return St; +} + +const GRState* RegionStoreManager::KillStruct(const GRState* St, + const TypedRegion* R){ + GRStateRef state(St, StateMgr); + + // Kill the struct region because it is assigned "unknown". + St = state.add<RegionKills>(R); + + // Set the default value of the struct region to "unknown". + St = state.set<RegionDefaultValue>(R, UnknownVal()); + + Store store = St->getStore(); + RegionBindingsTy B = GetRegionBindings(store); + + // Remove all bindings for the subregions of the struct. + for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) { + const MemRegion* r = I.getKey(); + if (const SubRegion* sr = dyn_cast<SubRegion>(r)) + if (sr->isSubRegionOf(R)) + store = Remove(store, Loc::MakeVal(sr)); + // FIXME: Maybe we should also remove the bindings for the "views" of the + // subregions. + } + + return StateMgr.MakeStateWithStore(St, store); +} + +const GRState* RegionStoreManager::AddRegionView(const GRState* St, + const MemRegion* View, + const MemRegion* Base) { + GRStateRef state(St, StateMgr); + + // First, retrieve the region view of the base region. + const RegionViews* d = state.get<RegionViewMap>(Base); + RegionViews L = d ? *d : RVFactory.GetEmptySet(); + + // Now add View to the region view. + L = RVFactory.Add(L, View); + + // Create a new state with the new region view. + return state.set<RegionViewMap>(Base, L); +} + +const GRState* RegionStoreManager::RemoveRegionView(const GRState* St, + const MemRegion* View, + const MemRegion* Base) { + GRStateRef state(St, StateMgr); + + // Retrieve the region view of the base region. + const RegionViews* d = state.get<RegionViewMap>(Base); + + // If the base region has no view, return. + if (!d) + return St; + + // Remove the view. + RegionViews V = *d; + V = RVFactory.Remove(V, View); + + return state.set<RegionViewMap>(Base, V); +} + +const GRState* RegionStoreManager::setCastType(const GRState* St, + const MemRegion* R, QualType T) { + GRStateRef state(St, StateMgr); + return state.set<RegionCasts>(R, T); +} + +const GRState* RegionStoreManager::setDefaultValue(const GRState* St, + const MemRegion* R, SVal V) { + GRStateRef state(St, StateMgr); + return state.set<RegionDefaultValue>(R, V); +} |
