forked from OSchip/llvm-project
336 lines
12 KiB
C++
336 lines
12 KiB
C++
//== Store.cpp - Interface for maps from Locations to Values ----*- C++ -*--==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defined the types Store and StoreManager.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Checker/PathSensitive/Store.h"
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#include "clang/Checker/PathSensitive/GRState.h"
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#include "clang/AST/CharUnits.h"
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using namespace clang;
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StoreManager::StoreManager(GRStateManager &stateMgr)
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: ValMgr(stateMgr.getValueManager()), StateMgr(stateMgr),
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MRMgr(ValMgr.getRegionManager()), Ctx(stateMgr.getContext()) {}
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const MemRegion *StoreManager::MakeElementRegion(const MemRegion *Base,
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QualType EleTy, uint64_t index) {
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SVal idx = ValMgr.makeArrayIndex(index);
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return MRMgr.getElementRegion(EleTy, idx, Base, ValMgr.getContext());
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}
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// FIXME: Merge with the implementation of the same method in MemRegion.cpp
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static bool IsCompleteType(ASTContext &Ctx, QualType Ty) {
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if (const RecordType *RT = Ty->getAs<RecordType>()) {
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const RecordDecl *D = RT->getDecl();
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if (!D->getDefinition())
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return false;
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}
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return true;
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}
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const ElementRegion *StoreManager::GetElementZeroRegion(const MemRegion *R,
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QualType T) {
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SVal idx = ValMgr.makeZeroArrayIndex();
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assert(!T.isNull());
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return MRMgr.getElementRegion(T, idx, R, Ctx);
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}
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const MemRegion *StoreManager::CastRegion(const MemRegion *R, QualType CastToTy) {
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ASTContext& Ctx = StateMgr.getContext();
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// Handle casts to Objective-C objects.
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if (CastToTy->isObjCObjectPointerType())
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return R->StripCasts();
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if (CastToTy->isBlockPointerType()) {
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// FIXME: We may need different solutions, depending on the symbol
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// involved. Blocks can be casted to/from 'id', as they can be treated
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// as Objective-C objects. This could possibly be handled by enhancing
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// our reasoning of downcasts of symbolic objects.
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if (isa<CodeTextRegion>(R) || isa<SymbolicRegion>(R))
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return R;
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// We don't know what to make of it. Return a NULL region, which
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// will be interpretted as UnknownVal.
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return NULL;
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}
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// Now assume we are casting from pointer to pointer. Other cases should
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// already be handled.
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QualType PointeeTy = CastToTy->getAs<PointerType>()->getPointeeType();
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QualType CanonPointeeTy = Ctx.getCanonicalType(PointeeTy);
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// Handle casts to void*. We just pass the region through.
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if (CanonPointeeTy.getLocalUnqualifiedType() == Ctx.VoidTy)
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return R;
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// Handle casts from compatible types.
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if (R->isBoundable())
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if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) {
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QualType ObjTy = Ctx.getCanonicalType(TR->getValueType(Ctx));
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if (CanonPointeeTy == ObjTy)
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return R;
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}
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// Process region cast according to the kind of the region being cast.
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switch (R->getKind()) {
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case MemRegion::CXXThisRegionKind:
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case MemRegion::GenericMemSpaceRegionKind:
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case MemRegion::StackLocalsSpaceRegionKind:
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case MemRegion::StackArgumentsSpaceRegionKind:
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case MemRegion::HeapSpaceRegionKind:
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case MemRegion::UnknownSpaceRegionKind:
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case MemRegion::GlobalsSpaceRegionKind: {
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assert(0 && "Invalid region cast");
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break;
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}
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case MemRegion::FunctionTextRegionKind:
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case MemRegion::BlockTextRegionKind:
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case MemRegion::BlockDataRegionKind: {
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// CodeTextRegion should be cast to only a function or block pointer type,
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// although they can in practice be casted to anything, e.g, void*, char*,
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// etc.
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// Just return the region.
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return R;
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}
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case MemRegion::StringRegionKind:
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// FIXME: Need to handle arbitrary downcasts.
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case MemRegion::SymbolicRegionKind:
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case MemRegion::AllocaRegionKind:
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case MemRegion::CompoundLiteralRegionKind:
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case MemRegion::FieldRegionKind:
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case MemRegion::ObjCIvarRegionKind:
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case MemRegion::VarRegionKind:
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case MemRegion::CXXObjectRegionKind:
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return MakeElementRegion(R, PointeeTy);
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case MemRegion::ElementRegionKind: {
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// If we are casting from an ElementRegion to another type, the
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// algorithm is as follows:
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//
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// (1) Compute the "raw offset" of the ElementRegion from the
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// base region. This is done by calling 'getAsRawOffset()'.
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//
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// (2a) If we get a 'RegionRawOffset' after calling
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// 'getAsRawOffset()', determine if the absolute offset
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// can be exactly divided into chunks of the size of the
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// casted-pointee type. If so, create a new ElementRegion with
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// the pointee-cast type as the new ElementType and the index
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// being the offset divded by the chunk size. If not, create
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// a new ElementRegion at offset 0 off the raw offset region.
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//
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// (2b) If we don't a get a 'RegionRawOffset' after calling
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// 'getAsRawOffset()', it means that we are at offset 0.
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//
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// FIXME: Handle symbolic raw offsets.
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const ElementRegion *elementR = cast<ElementRegion>(R);
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const RegionRawOffset &rawOff = elementR->getAsRawOffset();
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const MemRegion *baseR = rawOff.getRegion();
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// If we cannot compute a raw offset, throw up our hands and return
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// a NULL MemRegion*.
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if (!baseR)
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return NULL;
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CharUnits off = CharUnits::fromQuantity(rawOff.getByteOffset());
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if (off.isZero()) {
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// Edge case: we are at 0 bytes off the beginning of baseR. We
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// check to see if type we are casting to is the same as the base
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// region. If so, just return the base region.
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if (const TypedRegion *TR = dyn_cast<TypedRegion>(baseR)) {
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QualType ObjTy = Ctx.getCanonicalType(TR->getValueType(Ctx));
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QualType CanonPointeeTy = Ctx.getCanonicalType(PointeeTy);
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if (CanonPointeeTy == ObjTy)
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return baseR;
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}
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// Otherwise, create a new ElementRegion at offset 0.
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return MakeElementRegion(baseR, PointeeTy);
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}
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// We have a non-zero offset from the base region. We want to determine
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// if the offset can be evenly divided by sizeof(PointeeTy). If so,
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// we create an ElementRegion whose index is that value. Otherwise, we
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// create two ElementRegions, one that reflects a raw offset and the other
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// that reflects the cast.
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// Compute the index for the new ElementRegion.
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int64_t newIndex = 0;
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const MemRegion *newSuperR = 0;
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// We can only compute sizeof(PointeeTy) if it is a complete type.
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if (IsCompleteType(Ctx, PointeeTy)) {
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// Compute the size in **bytes**.
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CharUnits pointeeTySize = Ctx.getTypeSizeInChars(PointeeTy);
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if (!pointeeTySize.isZero()) {
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// Is the offset a multiple of the size? If so, we can layer the
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// ElementRegion (with elementType == PointeeTy) directly on top of
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// the base region.
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if (off % pointeeTySize == 0) {
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newIndex = off / pointeeTySize;
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newSuperR = baseR;
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}
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}
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}
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if (!newSuperR) {
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// Create an intermediate ElementRegion to represent the raw byte.
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// This will be the super region of the final ElementRegion.
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newSuperR = MakeElementRegion(baseR, Ctx.CharTy, off.getQuantity());
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}
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return MakeElementRegion(newSuperR, PointeeTy, newIndex);
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}
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}
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assert(0 && "unreachable");
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return 0;
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}
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/// CastRetrievedVal - Used by subclasses of StoreManager to implement
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/// implicit casts that arise from loads from regions that are reinterpreted
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/// as another region.
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SVal StoreManager::CastRetrievedVal(SVal V, const TypedRegion *R,
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QualType castTy, bool performTestOnly) {
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if (castTy.isNull())
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return V;
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ASTContext &Ctx = ValMgr.getContext();
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if (performTestOnly) {
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// Automatically translate references to pointers.
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QualType T = R->getValueType(Ctx);
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if (const ReferenceType *RT = T->getAs<ReferenceType>())
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T = Ctx.getPointerType(RT->getPointeeType());
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assert(ValMgr.getContext().hasSameUnqualifiedType(castTy, T));
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return V;
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}
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if (const Loc *L = dyn_cast<Loc>(&V))
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return ValMgr.getSValuator().EvalCastL(*L, castTy);
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else if (const NonLoc *NL = dyn_cast<NonLoc>(&V))
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return ValMgr.getSValuator().EvalCastNL(*NL, castTy);
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return V;
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}
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Store StoreManager::InvalidateRegions(Store store,
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const MemRegion * const *I,
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const MemRegion * const *End,
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const Expr *E, unsigned Count,
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InvalidatedSymbols *IS) {
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for ( ; I != End ; ++I)
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store = InvalidateRegion(store, *I, E, Count, IS);
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return store;
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}
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SVal StoreManager::getLValueFieldOrIvar(const Decl* D, SVal Base) {
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if (Base.isUnknownOrUndef())
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return Base;
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Loc BaseL = cast<Loc>(Base);
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const MemRegion* BaseR = 0;
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switch (BaseL.getSubKind()) {
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case loc::MemRegionKind:
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BaseR = cast<loc::MemRegionVal>(BaseL).getRegion();
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break;
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case loc::GotoLabelKind:
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// These are anormal cases. Flag an undefined value.
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return UndefinedVal();
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case loc::ConcreteIntKind:
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// While these seem funny, this can happen through casts.
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// FIXME: What we should return is the field offset. For example,
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// add the field offset to the integer value. That way funny things
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// like this work properly: &(((struct foo *) 0xa)->f)
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return Base;
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default:
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assert(0 && "Unhandled Base.");
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return Base;
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}
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// NOTE: We must have this check first because ObjCIvarDecl is a subclass
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// of FieldDecl.
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if (const ObjCIvarDecl *ID = dyn_cast<ObjCIvarDecl>(D))
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return loc::MemRegionVal(MRMgr.getObjCIvarRegion(ID, BaseR));
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return loc::MemRegionVal(MRMgr.getFieldRegion(cast<FieldDecl>(D), BaseR));
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}
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SVal StoreManager::getLValueElement(QualType elementType, SVal Offset,
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SVal Base) {
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// If the base is an unknown or undefined value, just return it back.
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// FIXME: For absolute pointer addresses, we just return that value back as
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// well, although in reality we should return the offset added to that
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// value.
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if (Base.isUnknownOrUndef() || isa<loc::ConcreteInt>(Base))
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return Base;
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// Only handle integer offsets... for now.
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if (!isa<nonloc::ConcreteInt>(Offset))
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return UnknownVal();
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const MemRegion* BaseRegion = cast<loc::MemRegionVal>(Base).getRegion();
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// Pointer of any type can be cast and used as array base.
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const ElementRegion *ElemR = dyn_cast<ElementRegion>(BaseRegion);
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// Convert the offset to the appropriate size and signedness.
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Offset = ValMgr.convertToArrayIndex(Offset);
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if (!ElemR) {
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//
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// If the base region is not an ElementRegion, create one.
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// This can happen in the following example:
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//
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// char *p = __builtin_alloc(10);
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// p[1] = 8;
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//
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// Observe that 'p' binds to an AllocaRegion.
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//
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return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset,
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BaseRegion, Ctx));
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}
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SVal BaseIdx = ElemR->getIndex();
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if (!isa<nonloc::ConcreteInt>(BaseIdx))
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return UnknownVal();
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const llvm::APSInt& BaseIdxI = cast<nonloc::ConcreteInt>(BaseIdx).getValue();
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const llvm::APSInt& OffI = cast<nonloc::ConcreteInt>(Offset).getValue();
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assert(BaseIdxI.isSigned());
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// Compute the new index.
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SVal NewIdx = nonloc::ConcreteInt(
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ValMgr.getBasicValueFactory().getValue(BaseIdxI + OffI));
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// Construct the new ElementRegion.
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const MemRegion *ArrayR = ElemR->getSuperRegion();
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return loc::MemRegionVal(MRMgr.getElementRegion(elementType, NewIdx, ArrayR,
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Ctx));
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}
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