blob: 173fdd8d0056b2bb5e4e7bb43890e5e523ec3977 [file] [log] [blame]
//== Store.cpp - Interface for maps from Locations to 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 types Store and StoreManager.
#include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/DeclObjC.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
using namespace clang;
using namespace ento;
StoreManager::StoreManager(ProgramStateManager &stateMgr)
: svalBuilder(stateMgr.getSValBuilder()), StateMgr(stateMgr),
MRMgr(svalBuilder.getRegionManager()), Ctx(stateMgr.getContext()) {}
StoreRef StoreManager::enterStackFrame(Store OldStore,
const CallEvent &Call,
const StackFrameContext *LCtx) {
StoreRef Store = StoreRef(OldStore, *this);
SmallVector<CallEvent::FrameBindingTy, 16> InitialBindings;
Call.getInitialStackFrameContents(LCtx, InitialBindings);
for (CallEvent::BindingsTy::iterator I = InitialBindings.begin(),
E = InitialBindings.end();
I != E; ++I) {
Store = Bind(Store.getStore(), I->first, I->second);
return Store;
const ElementRegion *StoreManager::MakeElementRegion(const SubRegion *Base,
QualType EleTy,
uint64_t index) {
NonLoc idx = svalBuilder.makeArrayIndex(index);
return MRMgr.getElementRegion(EleTy, idx, Base, svalBuilder.getContext());
StoreRef StoreManager::BindDefault(Store store, const MemRegion *R, SVal V) {
return StoreRef(store, *this);
const ElementRegion *StoreManager::GetElementZeroRegion(const SubRegion *R,
QualType T) {
NonLoc idx = svalBuilder.makeZeroArrayIndex();
return MRMgr.getElementRegion(T, idx, R, Ctx);
const MemRegion *StoreManager::castRegion(const MemRegion *R, QualType CastToTy) {
ASTContext &Ctx = StateMgr.getContext();
// Handle casts to Objective-C objects.
if (CastToTy->isObjCObjectPointerType())
return R->StripCasts();
if (CastToTy->isBlockPointerType()) {
// FIXME: We may need different solutions, depending on the symbol
// involved. Blocks can be casted to/from 'id', as they can be treated
// as Objective-C objects. This could possibly be handled by enhancing
// our reasoning of downcasts of symbolic objects.
if (isa<CodeTextRegion>(R) || isa<SymbolicRegion>(R))
return R;
// We don't know what to make of it. Return a NULL region, which
// will be interpretted as UnknownVal.
return nullptr;
// Now assume we are casting from pointer to pointer. Other cases should
// already be handled.
QualType PointeeTy = CastToTy->getPointeeType();
QualType CanonPointeeTy = Ctx.getCanonicalType(PointeeTy);
// Handle casts to void*. We just pass the region through.
if (CanonPointeeTy.getLocalUnqualifiedType() == Ctx.VoidTy)
return R;
// Handle casts from compatible types.
if (R->isBoundable())
if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
QualType ObjTy = Ctx.getCanonicalType(TR->getValueType());
if (CanonPointeeTy == ObjTy)
return R;
// Process region cast according to the kind of the region being cast.
switch (R->getKind()) {
case MemRegion::CXXThisRegionKind:
case MemRegion::CodeSpaceRegionKind:
case MemRegion::StackLocalsSpaceRegionKind:
case MemRegion::StackArgumentsSpaceRegionKind:
case MemRegion::HeapSpaceRegionKind:
case MemRegion::UnknownSpaceRegionKind:
case MemRegion::StaticGlobalSpaceRegionKind:
case MemRegion::GlobalInternalSpaceRegionKind:
case MemRegion::GlobalSystemSpaceRegionKind:
case MemRegion::GlobalImmutableSpaceRegionKind: {
llvm_unreachable("Invalid region cast");
case MemRegion::FunctionCodeRegionKind:
case MemRegion::BlockCodeRegionKind:
case MemRegion::BlockDataRegionKind:
case MemRegion::StringRegionKind:
// FIXME: Need to handle arbitrary downcasts.
case MemRegion::SymbolicRegionKind:
case MemRegion::AllocaRegionKind:
case MemRegion::CompoundLiteralRegionKind:
case MemRegion::FieldRegionKind:
case MemRegion::ObjCIvarRegionKind:
case MemRegion::ObjCStringRegionKind:
case MemRegion::VarRegionKind:
case MemRegion::CXXTempObjectRegionKind:
case MemRegion::CXXBaseObjectRegionKind:
return MakeElementRegion(cast<SubRegion>(R), PointeeTy);
case MemRegion::ElementRegionKind: {
// If we are casting from an ElementRegion to another type, the
// algorithm is as follows:
// (1) Compute the "raw offset" of the ElementRegion from the
// base region. This is done by calling 'getAsRawOffset()'.
// (2a) If we get a 'RegionRawOffset' after calling
// 'getAsRawOffset()', determine if the absolute offset
// can be exactly divided into chunks of the size of the
// casted-pointee type. If so, create a new ElementRegion with
// the pointee-cast type as the new ElementType and the index
// being the offset divded by the chunk size. If not, create
// a new ElementRegion at offset 0 off the raw offset region.
// (2b) If we don't a get a 'RegionRawOffset' after calling
// 'getAsRawOffset()', it means that we are at offset 0.
// FIXME: Handle symbolic raw offsets.
const ElementRegion *elementR = cast<ElementRegion>(R);
const RegionRawOffset &rawOff = elementR->getAsArrayOffset();
const MemRegion *baseR = rawOff.getRegion();
// If we cannot compute a raw offset, throw up our hands and return
// a NULL MemRegion*.
if (!baseR)
return nullptr;
CharUnits off = rawOff.getOffset();
if (off.isZero()) {
// Edge case: we are at 0 bytes off the beginning of baseR. We
// check to see if type we are casting to is the same as the base
// region. If so, just return the base region.
if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(baseR)) {
QualType ObjTy = Ctx.getCanonicalType(TR->getValueType());
QualType CanonPointeeTy = Ctx.getCanonicalType(PointeeTy);
if (CanonPointeeTy == ObjTy)
return baseR;
// Otherwise, create a new ElementRegion at offset 0.
return MakeElementRegion(cast<SubRegion>(baseR), PointeeTy);
// We have a non-zero offset from the base region. We want to determine
// if the offset can be evenly divided by sizeof(PointeeTy). If so,
// we create an ElementRegion whose index is that value. Otherwise, we
// create two ElementRegions, one that reflects a raw offset and the other
// that reflects the cast.
// Compute the index for the new ElementRegion.
int64_t newIndex = 0;
const MemRegion *newSuperR = nullptr;
// We can only compute sizeof(PointeeTy) if it is a complete type.
if (!PointeeTy->isIncompleteType()) {
// Compute the size in **bytes**.
CharUnits pointeeTySize = Ctx.getTypeSizeInChars(PointeeTy);
if (!pointeeTySize.isZero()) {
// Is the offset a multiple of the size? If so, we can layer the
// ElementRegion (with elementType == PointeeTy) directly on top of
// the base region.
if (off % pointeeTySize == 0) {
newIndex = off / pointeeTySize;
newSuperR = baseR;
if (!newSuperR) {
// Create an intermediate ElementRegion to represent the raw byte.
// This will be the super region of the final ElementRegion.
newSuperR = MakeElementRegion(cast<SubRegion>(baseR), Ctx.CharTy,
return MakeElementRegion(cast<SubRegion>(newSuperR), PointeeTy, newIndex);
static bool regionMatchesCXXRecordType(SVal V, QualType Ty) {
const MemRegion *MR = V.getAsRegion();
if (!MR)
return true;
const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(MR);
if (!TVR)
return true;
const CXXRecordDecl *RD = TVR->getValueType()->getAsCXXRecordDecl();
if (!RD)
return true;
const CXXRecordDecl *Expected = Ty->getPointeeCXXRecordDecl();
if (!Expected)
Expected = Ty->getAsCXXRecordDecl();
return Expected->getCanonicalDecl() == RD->getCanonicalDecl();
SVal StoreManager::evalDerivedToBase(SVal Derived, const CastExpr *Cast) {
// Sanity check to avoid doing the wrong thing in the face of
// reinterpret_cast.
if (!regionMatchesCXXRecordType(Derived, Cast->getSubExpr()->getType()))
return UnknownVal();
// Walk through the cast path to create nested CXXBaseRegions.
SVal Result = Derived;
for (CastExpr::path_const_iterator I = Cast->path_begin(),
E = Cast->path_end();
I != E; ++I) {
Result = evalDerivedToBase(Result, (*I)->getType(), (*I)->isVirtual());
return Result;
SVal StoreManager::evalDerivedToBase(SVal Derived, const CXXBasePath &Path) {
// Walk through the path to create nested CXXBaseRegions.
SVal Result = Derived;
for (CXXBasePath::const_iterator I = Path.begin(), E = Path.end();
I != E; ++I) {
Result = evalDerivedToBase(Result, I->Base->getType(),
return Result;
SVal StoreManager::evalDerivedToBase(SVal Derived, QualType BaseType,
bool IsVirtual) {
Optional<loc::MemRegionVal> DerivedRegVal =
if (!DerivedRegVal)
return Derived;
const CXXRecordDecl *BaseDecl = BaseType->getPointeeCXXRecordDecl();
if (!BaseDecl)
BaseDecl = BaseType->getAsCXXRecordDecl();
assert(BaseDecl && "not a C++ object?");
const MemRegion *BaseReg = MRMgr.getCXXBaseObjectRegion(
BaseDecl, cast<SubRegion>(DerivedRegVal->getRegion()), IsVirtual);
return loc::MemRegionVal(BaseReg);
/// Returns the static type of the given region, if it represents a C++ class
/// object.
/// This handles both fully-typed regions, where the dynamic type is known, and
/// symbolic regions, where the dynamic type is merely bounded (and even then,
/// only ostensibly!), but does not take advantage of any dynamic type info.
static const CXXRecordDecl *getCXXRecordType(const MemRegion *MR) {
if (const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(MR))
return TVR->getValueType()->getAsCXXRecordDecl();
if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR))
return SR->getSymbol()->getType()->getPointeeCXXRecordDecl();
return nullptr;
SVal StoreManager::attemptDownCast(SVal Base, QualType TargetType,
bool &Failed) {
Failed = false;
const MemRegion *MR = Base.getAsRegion();
if (!MR)
return UnknownVal();
// Assume the derived class is a pointer or a reference to a CXX record.
TargetType = TargetType->getPointeeType();
const CXXRecordDecl *TargetClass = TargetType->getAsCXXRecordDecl();
if (!TargetClass && !TargetType->isVoidType())
return UnknownVal();
// Drill down the CXXBaseObject chains, which represent upcasts (casts from
// derived to base).
while (const CXXRecordDecl *MRClass = getCXXRecordType(MR)) {
// If found the derived class, the cast succeeds.
if (MRClass == TargetClass)
return loc::MemRegionVal(MR);
// We skip over incomplete types. They must be the result of an earlier
// reinterpret_cast, as one can only dynamic_cast between types in the same
// class hierarchy.
if (!TargetType->isVoidType() && MRClass->hasDefinition()) {
// Static upcasts are marked as DerivedToBase casts by Sema, so this will
// only happen when multiple or virtual inheritance is involved.
CXXBasePaths Paths(/*FindAmbiguities=*/false, /*RecordPaths=*/true,
if (MRClass->isDerivedFrom(TargetClass, Paths))
return evalDerivedToBase(loc::MemRegionVal(MR), Paths.front());
if (const CXXBaseObjectRegion *BaseR = dyn_cast<CXXBaseObjectRegion>(MR)) {
// Drill down the chain to get the derived classes.
MR = BaseR->getSuperRegion();
// If this is a cast to void*, return the region.
if (TargetType->isVoidType())
return loc::MemRegionVal(MR);
// Strange use of reinterpret_cast can give us paths we don't reason
// about well, by putting in ElementRegions where we'd expect
// CXXBaseObjectRegions. If it's a valid reinterpret_cast (i.e. if the
// derived class has a zero offset from the base class), then it's safe
// to strip the cast; if it's invalid, -Wreinterpret-base-class should
// catch it. In the interest of performance, the analyzer will silently
// do the wrong thing in the invalid case (because offsets for subregions
// will be wrong).
const MemRegion *Uncasted = MR->StripCasts(/*IncludeBaseCasts=*/false);
if (Uncasted == MR) {
// We reached the bottom of the hierarchy and did not find the derived
// class. We we must be casting the base to derived, so the cast should
// fail.
MR = Uncasted;
// We failed if the region we ended up with has perfect type info.
Failed = isa<TypedValueRegion>(MR);
return UnknownVal();
/// CastRetrievedVal - Used by subclasses of StoreManager to implement
/// implicit casts that arise from loads from regions that are reinterpreted
/// as another region.
SVal StoreManager::CastRetrievedVal(SVal V, const TypedValueRegion *R,
QualType castTy, bool performTestOnly) {
if (castTy.isNull() || V.isUnknownOrUndef())
return V;
ASTContext &Ctx = svalBuilder.getContext();
if (performTestOnly) {
// Automatically translate references to pointers.
QualType T = R->getValueType();
if (const ReferenceType *RT = T->getAs<ReferenceType>())
T = Ctx.getPointerType(RT->getPointeeType());
assert(svalBuilder.getContext().hasSameUnqualifiedType(castTy, T));
return V;
return svalBuilder.dispatchCast(V, castTy);
SVal StoreManager::getLValueFieldOrIvar(const Decl *D, SVal Base) {
if (Base.isUnknownOrUndef())
return Base;
Loc BaseL = Base.castAs<Loc>();
const SubRegion* BaseR = nullptr;
switch (BaseL.getSubKind()) {
case loc::MemRegionValKind:
BaseR = cast<SubRegion>(BaseL.castAs<loc::MemRegionVal>().getRegion());
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, not base. For example,
// add the field offset to the integer value. That way things
// like this work properly: &(((struct foo *) 0xa)->f)
// However, that's not easy to fix without reducing our abilities
// to catch null pointer dereference. Eg., ((struct foo *)0x0)->f = 7
// is a null dereference even though we're dereferencing offset of f
// rather than null. Coming up with an approach that computes offsets
// over null pointers properly while still being able to catch null
// dereferences might be worth it.
return Base;
llvm_unreachable("Unhandled 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 StoreManager::getLValueIvar(const ObjCIvarDecl *decl, SVal base) {
return getLValueFieldOrIvar(decl, base);
SVal StoreManager::getLValueElement(QualType elementType, NonLoc Offset,
SVal Base) {
// 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. See also the similar FIXME in getLValueFieldOrIvar().
if (Base.isUnknownOrUndef() || Base.getAs<loc::ConcreteInt>())
return Base;
if (Base.getAs<loc::GotoLabel>())
return UnknownVal();
const SubRegion *BaseRegion =
// Pointer of any type can be cast and used as array base.
const ElementRegion *ElemR = dyn_cast<ElementRegion>(BaseRegion);
// Convert the offset to the appropriate size and signedness.
Offset = svalBuilder.convertToArrayIndex(Offset).castAs<NonLoc>();
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.
return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset,
BaseRegion, Ctx));
SVal BaseIdx = ElemR->getIndex();
if (!BaseIdx.getAs<nonloc::ConcreteInt>())
return UnknownVal();
const llvm::APSInt &BaseIdxI =
// Only allow non-integer offsets if the base region has no offset itself.
// FIXME: This is a somewhat arbitrary restriction. We should be using
// SValBuilder here to add the two offsets without checking their types.
if (!Offset.getAs<nonloc::ConcreteInt>()) {
if (isa<ElementRegion>(BaseRegion->StripCasts()))
return UnknownVal();
return loc::MemRegionVal(MRMgr.getElementRegion(
elementType, Offset, cast<SubRegion>(ElemR->getSuperRegion()), Ctx));
const llvm::APSInt& OffI = Offset.castAs<nonloc::ConcreteInt>().getValue();
// Compute the new index.
nonloc::ConcreteInt NewIdx(svalBuilder.getBasicValueFactory().getValue(BaseIdxI +
// Construct the new ElementRegion.
const SubRegion *ArrayR = cast<SubRegion>(ElemR->getSuperRegion());
return loc::MemRegionVal(MRMgr.getElementRegion(elementType, NewIdx, ArrayR,
StoreManager::BindingsHandler::~BindingsHandler() {}
bool StoreManager::FindUniqueBinding::HandleBinding(StoreManager& SMgr,
Store store,
const MemRegion* R,
SVal val) {
SymbolRef SymV = val.getAsLocSymbol();
if (!SymV || SymV != Sym)
return true;
if (Binding) {
First = false;
return false;
Binding = R;
return true;