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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/Analysis/PathSensitive/Store.h"
#include "clang/Analysis/PathSensitive/GRState.h"
using namespace clang;
StoreManager::StoreManager(GRStateManager &stateMgr)
: ValMgr(stateMgr.getValueManager()), StateMgr(stateMgr),
MRMgr(ValMgr.getRegionManager()) {}
const MemRegion *StoreManager::MakeElementRegion(const MemRegion *Base,
QualType EleTy, uint64_t index) {
SVal idx = ValMgr.makeArrayIndex(index);
return MRMgr.getElementRegion(EleTy, idx, Base, ValMgr.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(Ctx))
return false;
}
return true;
}
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->getAs<PointerType>()->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 TypedRegion *TR = dyn_cast<TypedRegion>(R)) {
QualType ObjTy = Ctx.getCanonicalType(TR->getValueType(Ctx));
if (CanonPointeeTy == ObjTy)
return R;
}
// Process region cast according to the kind of the region being cast.
switch (R->getKind()) {
case MemRegion::BEG_TYPED_REGIONS:
case MemRegion::MemSpaceRegionKind:
case MemRegion::BEG_DECL_REGIONS:
case MemRegion::END_DECL_REGIONS:
case MemRegion::END_TYPED_REGIONS: {
assert(0 && "Invalid region cast");
break;
}
case MemRegion::CodeTextRegionKind: {
// CodeTextRegion should be cast to only a function or block pointer type,
// although they can in practice be casted to anything, e.g, void*, char*,
// etc.
// Just return the region.
return R;
}
case MemRegion::StringRegionKind:
case MemRegion::ObjCObjectRegionKind:
// FIXME: Need to handle arbitrary downcasts.
case MemRegion::SymbolicRegionKind:
case MemRegion::AllocaRegionKind:
case MemRegion::CompoundLiteralRegionKind:
case MemRegion::FieldRegionKind:
case MemRegion::ObjCIvarRegionKind:
case MemRegion::VarRegionKind:
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->getAsRawOffset();
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;
int64_t off = rawOff.getByteOffset();
if (off == 0) {
// 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 TypedRegion *TR = dyn_cast<TypedRegion>(baseR)) {
QualType ObjTy = Ctx.getCanonicalType(TR->getValueType(Ctx));
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**.
int64_t pointeeTySize = (int64_t) (Ctx.getTypeSize(PointeeTy) / 8);
// 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);
}
return MakeElementRegion(newSuperR, PointeeTy, newIndex);
}
}
assert(0 && "unreachable");
return 0;
}
/// 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 TypedRegion *R,
QualType castTy) {
ASTContext &Ctx = ValMgr.getContext();
if (castTy.isNull())
return V;
assert(Ctx.hasSameUnqualifiedType(castTy, R->getValueType(Ctx)));
return V;
}
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