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//== 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/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/AST/CharUnits.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(const ProgramState *state,
const StackFrameContext *frame) {
return StoreRef(state->getStore(), *this);
}
const MemRegion *StoreManager::MakeElementRegion(const MemRegion *Base,
QualType EleTy, uint64_t index) {
NonLoc idx = svalBuilder.makeArrayIndex(index);
return MRMgr.getElementRegion(EleTy, idx, Base, svalBuilder.getContext());
}
// FIXME: Merge with the implementation of the same method in MemRegion.cpp
static bool IsCompleteType(ASTContext &Ctx, QualType Ty) {
if (const RecordType *RT = Ty->getAs<RecordType>()) {
const RecordDecl *D = RT->getDecl();
if (!D->getDefinition())
return false;
}
return true;
}
StoreRef StoreManager::BindDefault(Store store, const MemRegion *R, SVal V) {
return StoreRef(store, *this);
}
const ElementRegion *StoreManager::GetElementZeroRegion(const MemRegion *R,
QualType T) {
NonLoc idx = svalBuilder.makeZeroArrayIndex();
assert(!T.isNull());
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 NULL;
}
// 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::GenericMemSpaceRegionKind:
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::FunctionTextRegionKind:
case MemRegion::BlockTextRegionKind:
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::VarRegionKind:
case MemRegion::CXXTempObjectRegionKind:
case MemRegion::CXXBaseObjectRegionKind:
return MakeElementRegion(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 NULL;
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(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 = 0;
// We can only compute sizeof(PointeeTy) if it is a complete type.
if (IsCompleteType(Ctx, PointeeTy)) {
// 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(baseR, Ctx.CharTy, off.getQuantity());
}
return MakeElementRegion(newSuperR, PointeeTy, newIndex);
}
}
llvm_unreachable("unreachable");
}
/// 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 = 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:
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::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.
if (Base.isUnknownOrUndef() || isa<loc::ConcreteInt>(Base))
return Base;
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);
// Convert the offset to the appropriate size and signedness.
Offset = cast<NonLoc>(svalBuilder.convertToArrayIndex(Offset));
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 (!isa<nonloc::ConcreteInt>(BaseIdx))
return UnknownVal();
const llvm::APSInt& BaseIdxI = cast<nonloc::ConcreteInt>(BaseIdx).getValue();
// 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 (!isa<nonloc::ConcreteInt>(Offset)) {
if (isa<ElementRegion>(BaseRegion->StripCasts()))
return UnknownVal();
return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset,
ElemR->getSuperRegion(),
Ctx));
}
const llvm::APSInt& OffI = cast<nonloc::ConcreteInt>(Offset).getValue();
assert(BaseIdxI.isSigned());
// Compute the new index.
nonloc::ConcreteInt NewIdx(svalBuilder.getBasicValueFactory().getValue(BaseIdxI +
OffI));
// Construct the new ElementRegion.
const MemRegion *ArrayR = ElemR->getSuperRegion();
return loc::MemRegionVal(MRMgr.getElementRegion(elementType, NewIdx, ArrayR,
Ctx));
}
StoreManager::BindingsHandler::~BindingsHandler() {}
void SubRegionMap::anchor() { }
void SubRegionMap::Visitor::anchor() { }