522 lines
19 KiB
C++
522 lines
19 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/StaticAnalyzer/Core/PathSensitive/Store.h"
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#include "clang/AST/CXXInheritance.h"
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#include "clang/AST/CharUnits.h"
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#include "clang/AST/DeclObjC.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
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using namespace clang;
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using namespace ento;
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StoreManager::StoreManager(ProgramStateManager &stateMgr)
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: svalBuilder(stateMgr.getSValBuilder()), StateMgr(stateMgr),
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MRMgr(svalBuilder.getRegionManager()), Ctx(stateMgr.getContext()) {}
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StoreRef StoreManager::enterStackFrame(Store OldStore,
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const CallEvent &Call,
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const StackFrameContext *LCtx) {
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StoreRef Store = StoreRef(OldStore, *this);
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SmallVector<CallEvent::FrameBindingTy, 16> InitialBindings;
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Call.getInitialStackFrameContents(LCtx, InitialBindings);
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for (CallEvent::BindingsTy::iterator I = InitialBindings.begin(),
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E = InitialBindings.end();
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I != E; ++I) {
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Store = Bind(Store.getStore(), I->first, I->second);
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}
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return Store;
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}
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const MemRegion *StoreManager::MakeElementRegion(const MemRegion *Base,
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QualType EleTy, uint64_t index) {
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NonLoc idx = svalBuilder.makeArrayIndex(index);
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return MRMgr.getElementRegion(EleTy, idx, Base, svalBuilder.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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StoreRef StoreManager::BindDefault(Store store, const MemRegion *R, SVal V) {
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return StoreRef(store, *this);
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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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NonLoc idx = svalBuilder.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 nullptr;
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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->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 TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
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QualType ObjTy = Ctx.getCanonicalType(TR->getValueType());
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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::StaticGlobalSpaceRegionKind:
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case MemRegion::GlobalInternalSpaceRegionKind:
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case MemRegion::GlobalSystemSpaceRegionKind:
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case MemRegion::GlobalImmutableSpaceRegionKind: {
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llvm_unreachable("Invalid region cast");
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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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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::ObjCStringRegionKind:
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case MemRegion::VarRegionKind:
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case MemRegion::CXXTempObjectRegionKind:
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case MemRegion::CXXBaseObjectRegionKind:
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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->getAsArrayOffset();
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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 nullptr;
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CharUnits off = rawOff.getOffset();
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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 TypedValueRegion *TR = dyn_cast<TypedValueRegion>(baseR)) {
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QualType ObjTy = Ctx.getCanonicalType(TR->getValueType());
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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 = nullptr;
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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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llvm_unreachable("unreachable");
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}
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static bool regionMatchesCXXRecordType(SVal V, QualType Ty) {
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const MemRegion *MR = V.getAsRegion();
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if (!MR)
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return true;
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const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(MR);
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if (!TVR)
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return true;
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const CXXRecordDecl *RD = TVR->getValueType()->getAsCXXRecordDecl();
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if (!RD)
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return true;
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const CXXRecordDecl *Expected = Ty->getPointeeCXXRecordDecl();
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if (!Expected)
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Expected = Ty->getAsCXXRecordDecl();
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return Expected->getCanonicalDecl() == RD->getCanonicalDecl();
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}
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SVal StoreManager::evalDerivedToBase(SVal Derived, const CastExpr *Cast) {
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// Sanity check to avoid doing the wrong thing in the face of
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// reinterpret_cast.
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if (!regionMatchesCXXRecordType(Derived, Cast->getSubExpr()->getType()))
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return UnknownVal();
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// Walk through the cast path to create nested CXXBaseRegions.
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SVal Result = Derived;
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for (CastExpr::path_const_iterator I = Cast->path_begin(),
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E = Cast->path_end();
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I != E; ++I) {
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Result = evalDerivedToBase(Result, (*I)->getType(), (*I)->isVirtual());
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}
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return Result;
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}
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SVal StoreManager::evalDerivedToBase(SVal Derived, const CXXBasePath &Path) {
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// Walk through the path to create nested CXXBaseRegions.
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SVal Result = Derived;
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for (CXXBasePath::const_iterator I = Path.begin(), E = Path.end();
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I != E; ++I) {
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Result = evalDerivedToBase(Result, I->Base->getType(),
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I->Base->isVirtual());
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}
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return Result;
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}
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SVal StoreManager::evalDerivedToBase(SVal Derived, QualType BaseType,
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bool IsVirtual) {
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Optional<loc::MemRegionVal> DerivedRegVal =
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Derived.getAs<loc::MemRegionVal>();
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if (!DerivedRegVal)
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return Derived;
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const CXXRecordDecl *BaseDecl = BaseType->getPointeeCXXRecordDecl();
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if (!BaseDecl)
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BaseDecl = BaseType->getAsCXXRecordDecl();
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assert(BaseDecl && "not a C++ object?");
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const MemRegion *BaseReg =
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MRMgr.getCXXBaseObjectRegion(BaseDecl, DerivedRegVal->getRegion(),
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IsVirtual);
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return loc::MemRegionVal(BaseReg);
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}
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/// Returns the static type of the given region, if it represents a C++ class
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/// object.
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///
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/// This handles both fully-typed regions, where the dynamic type is known, and
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/// symbolic regions, where the dynamic type is merely bounded (and even then,
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/// only ostensibly!), but does not take advantage of any dynamic type info.
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static const CXXRecordDecl *getCXXRecordType(const MemRegion *MR) {
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if (const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(MR))
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return TVR->getValueType()->getAsCXXRecordDecl();
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if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR))
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return SR->getSymbol()->getType()->getPointeeCXXRecordDecl();
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return nullptr;
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}
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SVal StoreManager::evalDynamicCast(SVal Base, QualType TargetType,
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bool &Failed) {
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Failed = false;
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const MemRegion *MR = Base.getAsRegion();
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if (!MR)
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return UnknownVal();
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// Assume the derived class is a pointer or a reference to a CXX record.
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TargetType = TargetType->getPointeeType();
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assert(!TargetType.isNull());
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const CXXRecordDecl *TargetClass = TargetType->getAsCXXRecordDecl();
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if (!TargetClass && !TargetType->isVoidType())
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return UnknownVal();
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// Drill down the CXXBaseObject chains, which represent upcasts (casts from
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// derived to base).
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while (const CXXRecordDecl *MRClass = getCXXRecordType(MR)) {
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// If found the derived class, the cast succeeds.
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if (MRClass == TargetClass)
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return loc::MemRegionVal(MR);
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// We skip over incomplete types. They must be the result of an earlier
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// reinterpret_cast, as one can only dynamic_cast between types in the same
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// class hierarchy.
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if (!TargetType->isVoidType() && MRClass->hasDefinition()) {
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// Static upcasts are marked as DerivedToBase casts by Sema, so this will
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// only happen when multiple or virtual inheritance is involved.
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CXXBasePaths Paths(/*FindAmbiguities=*/false, /*RecordPaths=*/true,
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/*DetectVirtual=*/false);
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if (MRClass->isDerivedFrom(TargetClass, Paths))
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return evalDerivedToBase(loc::MemRegionVal(MR), Paths.front());
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}
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if (const CXXBaseObjectRegion *BaseR = dyn_cast<CXXBaseObjectRegion>(MR)) {
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// Drill down the chain to get the derived classes.
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MR = BaseR->getSuperRegion();
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continue;
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}
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// If this is a cast to void*, return the region.
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if (TargetType->isVoidType())
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return loc::MemRegionVal(MR);
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// Strange use of reinterpret_cast can give us paths we don't reason
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// about well, by putting in ElementRegions where we'd expect
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// CXXBaseObjectRegions. If it's a valid reinterpret_cast (i.e. if the
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// derived class has a zero offset from the base class), then it's safe
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// to strip the cast; if it's invalid, -Wreinterpret-base-class should
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// catch it. In the interest of performance, the analyzer will silently
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// do the wrong thing in the invalid case (because offsets for subregions
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// will be wrong).
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const MemRegion *Uncasted = MR->StripCasts(/*IncludeBaseCasts=*/false);
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if (Uncasted == MR) {
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// We reached the bottom of the hierarchy and did not find the derived
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// class. We we must be casting the base to derived, so the cast should
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// fail.
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break;
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}
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MR = Uncasted;
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}
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// We failed if the region we ended up with has perfect type info.
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Failed = isa<TypedValueRegion>(MR);
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return UnknownVal();
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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 TypedValueRegion *R,
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QualType castTy, bool performTestOnly) {
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if (castTy.isNull() || V.isUnknownOrUndef())
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return V;
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ASTContext &Ctx = svalBuilder.getContext();
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if (performTestOnly) {
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// Automatically translate references to pointers.
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QualType T = R->getValueType();
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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(svalBuilder.getContext().hasSameUnqualifiedType(castTy, T));
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return V;
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}
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return svalBuilder.dispatchCast(V, castTy);
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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 = Base.castAs<Loc>();
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const MemRegion* BaseR = nullptr;
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switch (BaseL.getSubKind()) {
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case loc::MemRegionKind:
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BaseR = BaseL.castAs<loc::MemRegionVal>().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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llvm_unreachable("Unhandled 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::getLValueIvar(const ObjCIvarDecl *decl, SVal base) {
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return getLValueFieldOrIvar(decl, base);
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}
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SVal StoreManager::getLValueElement(QualType elementType, NonLoc 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() || Base.getAs<loc::ConcreteInt>())
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return Base;
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const MemRegion* BaseRegion = Base.castAs<loc::MemRegionVal>().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 = svalBuilder.convertToArrayIndex(Offset).castAs<NonLoc>();
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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 (!BaseIdx.getAs<nonloc::ConcreteInt>())
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return UnknownVal();
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const llvm::APSInt &BaseIdxI =
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BaseIdx.castAs<nonloc::ConcreteInt>().getValue();
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// Only allow non-integer offsets if the base region has no offset itself.
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// FIXME: This is a somewhat arbitrary restriction. We should be using
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// SValBuilder here to add the two offsets without checking their types.
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if (!Offset.getAs<nonloc::ConcreteInt>()) {
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if (isa<ElementRegion>(BaseRegion->StripCasts()))
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return UnknownVal();
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return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset,
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ElemR->getSuperRegion(),
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Ctx));
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}
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const llvm::APSInt& OffI = Offset.castAs<nonloc::ConcreteInt>().getValue();
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|
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() {}
|
|
|
|
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;
|
|
}
|
|
else
|
|
Binding = R;
|
|
|
|
return true;
|
|
}
|