wangtao
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
llvm-project/clang/lib/Analysis/RegionStore.cpp

1337 lines
46 KiB
C++
Raw Blame History

//== RegionStore.cpp - Field-sensitive store model --------------*- C++ -*--==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a basic region store model. In this model, we do have field
// sensitivity. But we assume nothing about the heap shape. So recursive data
// structures are largely ignored. Basically we do 1-limiting analysis.
// Parameter pointers are assumed with no aliasing. Pointee objects of
// parameters are created lazily.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/PathSensitive/MemRegion.h"
#include "clang/Analysis/PathSensitive/GRState.h"
#include "clang/Analysis/PathSensitive/GRStateTrait.h"
#include "clang/Analysis/Analyses/LiveVariables.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/ImmutableMap.h"
#include "llvm/ADT/ImmutableList.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Compiler.h"
using namespace clang;
// Actual Store type.
typedef llvm::ImmutableMap<const MemRegion*, SVal> RegionBindingsTy;
//===----------------------------------------------------------------------===//
// Region "Views"
//===----------------------------------------------------------------------===//
//
// MemRegions can be layered on top of each other. This GDM entry tracks
// what are the MemRegions that layer a given MemRegion.
//
typedef llvm::ImmutableSet<const MemRegion*> RegionViews;
namespace { class VISIBILITY_HIDDEN RegionViewMap {}; }
static int RegionViewMapIndex = 0;
namespace clang {
template<> struct GRStateTrait<RegionViewMap>
: public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*,
RegionViews> > {
static void* GDMIndex() { return &RegionViewMapIndex; }
};
}
// RegionCasts records the current cast type of a region.
namespace { class VISIBILITY_HIDDEN RegionCasts {}; }
static int RegionCastsIndex = 0;
namespace clang {
template<> struct GRStateTrait<RegionCasts>
: public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*,
QualType> > {
static void* GDMIndex() { return &RegionCastsIndex; }
};
}
//===----------------------------------------------------------------------===//
// Region "Extents"
//===----------------------------------------------------------------------===//
//
// MemRegions represent chunks of memory with a size (their "extent"). This
// GDM entry tracks the extents for regions. Extents are in bytes.
//
namespace { class VISIBILITY_HIDDEN RegionExtents {}; }
static int RegionExtentsIndex = 0;
namespace clang {
template<> struct GRStateTrait<RegionExtents>
: public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*, SVal> > {
static void* GDMIndex() { return &RegionExtentsIndex; }
};
}
//===----------------------------------------------------------------------===//
// Region "killsets".
//===----------------------------------------------------------------------===//
//
// RegionStore lazily adds value bindings to regions when the analyzer handles
// assignment statements. Killsets track which default values have been
// killed, thus distinguishing between "unknown" values and default
// values. Regions are added to killset only when they are assigned "unknown"
// directly, otherwise we should have their value in the region bindings.
//
namespace { class VISIBILITY_HIDDEN RegionKills {}; }
static int RegionKillsIndex = 0;
namespace clang {
template<> struct GRStateTrait<RegionKills>
: public GRStatePartialTrait< llvm::ImmutableSet<const MemRegion*> > {
static void* GDMIndex() { return &RegionKillsIndex; }
};
}
//===----------------------------------------------------------------------===//
// Regions with default values.
//===----------------------------------------------------------------------===//
//
// This GDM entry tracks what regions have a default value if they have no bound
// value and have not been killed.
//
namespace { class VISIBILITY_HIDDEN RegionDefaultValue {}; }
static int RegionDefaultValueIndex = 0;
namespace clang {
template<> struct GRStateTrait<RegionDefaultValue>
: public GRStatePartialTrait<llvm::ImmutableMap<const MemRegion*, SVal> > {
static void* GDMIndex() { return &RegionDefaultValueIndex; }
};
}
//===----------------------------------------------------------------------===//
// Main RegionStore logic.
//===----------------------------------------------------------------------===//
namespace {
class VISIBILITY_HIDDEN RegionStoreSubRegionMap : public SubRegionMap {
typedef llvm::DenseMap<const MemRegion*,
llvm::ImmutableSet<const MemRegion*> > Map;
llvm::ImmutableSet<const MemRegion*>::Factory F;
Map M;
public:
void add(const MemRegion* Parent, const MemRegion* SubRegion) {
Map::iterator I = M.find(Parent);
M.insert(std::make_pair(Parent,
F.Add(I == M.end() ? F.GetEmptySet() : I->second, SubRegion)));
}
~RegionStoreSubRegionMap() {}
bool iterSubRegions(const MemRegion* Parent, Visitor& V) const {
Map::iterator I = M.find(Parent);
if (I == M.end())
return true;
llvm::ImmutableSet<const MemRegion*> S = I->second;
for (llvm::ImmutableSet<const MemRegion*>::iterator SI=S.begin(),SE=S.end();
SI != SE; ++SI) {
if (!V.Visit(Parent, *SI))
return false;
}
return true;
}
};
class VISIBILITY_HIDDEN RegionStoreManager : public StoreManager {
RegionBindingsTy::Factory RBFactory;
RegionViews::Factory RVFactory;
const MemRegion* SelfRegion;
const ImplicitParamDecl *SelfDecl;
public:
RegionStoreManager(GRStateManager& mgr)
: StoreManager(mgr),
RBFactory(mgr.getAllocator()),
RVFactory(mgr.getAllocator()),
SelfRegion(0), SelfDecl(0) {
if (const ObjCMethodDecl* MD =
dyn_cast<ObjCMethodDecl>(&StateMgr.getCodeDecl()))
SelfDecl = MD->getSelfDecl();
}
virtual ~RegionStoreManager() {}
SubRegionMap* getSubRegionMap(const GRState *state);
const GRState* BindCompoundLiteral(const GRState* St,
const CompoundLiteralExpr* CL, SVal V);
/// getLValueString - Returns an SVal representing the lvalue of a
/// StringLiteral. Within RegionStore a StringLiteral has an
/// associated StringRegion, and the lvalue of a StringLiteral is
/// the lvalue of that region.
SVal getLValueString(const GRState* St, const StringLiteral* S);
/// getLValueCompoundLiteral - Returns an SVal representing the
/// lvalue of a compound literal. Within RegionStore a compound
/// literal has an associated region, and the lvalue of the
/// compound literal is the lvalue of that region.
SVal getLValueCompoundLiteral(const GRState* St, const CompoundLiteralExpr*);
/// getLValueVar - Returns an SVal that represents the lvalue of a
/// variable. Within RegionStore a variable has an associated
/// VarRegion, and the lvalue of the variable is the lvalue of that region.
SVal getLValueVar(const GRState* St, const VarDecl* VD);
SVal getLValueIvar(const GRState* St, const ObjCIvarDecl* D, SVal Base);
SVal getLValueField(const GRState* St, SVal Base, const FieldDecl* D);
SVal getLValueFieldOrIvar(const GRState* St, SVal Base, const Decl* D);
SVal getLValueElement(const GRState* St, QualType elementType,
SVal Base, SVal Offset);
SVal getSizeInElements(const GRState* St, const MemRegion* R);
/// ArrayToPointer - Emulates the "decay" of an array to a pointer
/// type. 'Array' represents the lvalue of the array being decayed
/// to a pointer, and the returned SVal represents the decayed
/// version of that lvalue (i.e., a pointer to the first element of
/// the array). This is called by GRExprEngine when evaluating
/// casts from arrays to pointers.
SVal ArrayToPointer(Loc Array);
CastResult CastRegion(const GRState* state, const MemRegion* R,
QualType CastToTy);
SVal EvalBinOp(BinaryOperator::Opcode Op, Loc L, NonLoc R);
/// The high level logic for this method is this:
/// Retrieve (L)
/// if L has binding
/// return L's binding
/// else if L is in killset
/// return unknown
/// else
/// if L is on stack or heap
/// return undefined
/// else
/// return symbolic
SVal Retrieve(const GRState* state, Loc L, QualType T = QualType());
const GRState* Bind(const GRState* St, Loc LV, SVal V);
Store Remove(Store store, Loc LV);
Store getInitialStore() { return RBFactory.GetEmptyMap().getRoot(); }
/// getSelfRegion - Returns the region for the 'self' (Objective-C) or
/// 'this' object (C++). When used when analyzing a normal function this
/// method returns NULL.
const MemRegion* getSelfRegion(Store) {
if (!SelfDecl)
return 0;
if (!SelfRegion) {
const ObjCMethodDecl *MD = cast<ObjCMethodDecl>(&StateMgr.getCodeDecl());
SelfRegion = MRMgr.getObjCObjectRegion(MD->getClassInterface(),
MRMgr.getHeapRegion());
}
return SelfRegion;
}
/// RemoveDeadBindings - Scans the RegionStore of 'state' for dead values.
/// It returns a new Store with these values removed, and populates LSymbols
// and DSymbols with the known set of live and dead symbols respectively.
Store RemoveDeadBindings(const GRState* state, Stmt* Loc,
SymbolReaper& SymReaper,
llvm::SmallVectorImpl<const MemRegion*>& RegionRoots);
const GRState* BindDecl(const GRState* St, const VarDecl* VD, SVal InitVal);
const GRState* BindDeclWithNoInit(const GRState* St, const VarDecl* VD) {
return St;
}
const GRState* setExtent(const GRState* St, const MemRegion* R, SVal Extent);
const GRState* setCastType(const GRState* St, const MemRegion* R, QualType T);
static inline RegionBindingsTy GetRegionBindings(Store store) {
return RegionBindingsTy(static_cast<const RegionBindingsTy::TreeTy*>(store));
}
void print(Store store, std::ostream& Out, const char* nl, const char *sep);
void iterBindings(Store store, BindingsHandler& f) {
// FIXME: Implement.
}
private:
const GRState* BindArray(const GRState* St, const TypedRegion* R, SVal V);
/// Retrieve the values in a struct and return a CompoundVal, used when doing
/// struct copy:
/// struct s x, y;
/// x = y;
/// y's value is retrieved by this method.
SVal RetrieveStruct(const GRState* St, const TypedRegion* R);
SVal RetrieveArray(const GRState* St, const TypedRegion* R);
const GRState* BindStruct(const GRState* St, const TypedRegion* R, SVal V);
/// KillStruct - Set the entire struct to unknown.
const GRState* KillStruct(const GRState* St, const TypedRegion* R);
// Utility methods.
BasicValueFactory& getBasicVals() { return StateMgr.getBasicVals(); }
ASTContext& getContext() { return StateMgr.getContext(); }
SymbolManager& getSymbolManager() { return StateMgr.getSymbolManager(); }
const GRState* AddRegionView(const GRState* St,
const MemRegion* View, const MemRegion* Base);
const GRState* RemoveRegionView(const GRState* St,
const MemRegion* View, const MemRegion* Base);
};
} // end anonymous namespace
StoreManager* clang::CreateRegionStoreManager(GRStateManager& StMgr) {
return new RegionStoreManager(StMgr);
}
SubRegionMap* RegionStoreManager::getSubRegionMap(const GRState *state) {
RegionBindingsTy B = GetRegionBindings(state->getStore());
RegionStoreSubRegionMap *M = new RegionStoreSubRegionMap();
for (RegionBindingsTy::iterator I=B.begin(), E=B.end(); I!=E; ++I) {
if (const SubRegion* R = dyn_cast<SubRegion>(I.getKey()))
M->add(R->getSuperRegion(), R);
}
return M;
}
/// getLValueString - Returns an SVal representing the lvalue of a
/// StringLiteral. Within RegionStore a StringLiteral has an
/// associated StringRegion, and the lvalue of a StringLiteral is the
/// lvalue of that region.
SVal RegionStoreManager::getLValueString(const GRState* St,
const StringLiteral* S) {
return loc::MemRegionVal(MRMgr.getStringRegion(S));
}
/// getLValueVar - Returns an SVal that represents the lvalue of a
/// variable. Within RegionStore a variable has an associated
/// VarRegion, and the lvalue of the variable is the lvalue of that region.
SVal RegionStoreManager::getLValueVar(const GRState* St, const VarDecl* VD) {
return loc::MemRegionVal(MRMgr.getVarRegion(VD));
}
/// getLValueCompoundLiteral - Returns an SVal representing the lvalue
/// of a compound literal. Within RegionStore a compound literal
/// has an associated region, and the lvalue of the compound literal
/// is the lvalue of that region.
SVal
RegionStoreManager::getLValueCompoundLiteral(const GRState* St,
const CompoundLiteralExpr* CL) {
return loc::MemRegionVal(MRMgr.getCompoundLiteralRegion(CL));
}
SVal RegionStoreManager::getLValueIvar(const GRState* St, const ObjCIvarDecl* D,
SVal Base) {
return getLValueFieldOrIvar(St, Base, D);
}
SVal RegionStoreManager::getLValueField(const GRState* St, SVal Base,
const FieldDecl* D) {
return getLValueFieldOrIvar(St, Base, D);
}
SVal RegionStoreManager::getLValueFieldOrIvar(const GRState* St, SVal Base,
const Decl* D) {
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();
if (const SymbolicRegion* SR = dyn_cast<SymbolicRegion>(BaseR)) {
SymbolRef Sym = SR->getSymbol();
BaseR = MRMgr.getTypedViewRegion(Sym->getType(getContext()), SR);
}
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:
assert(0 && "Unhandled Base.");
return 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 RegionStoreManager::getLValueElement(const GRState* St,
QualType elementType,
SVal Base, SVal Offset) {
// 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;
// Only handle integer offsets... for now.
if (!isa<nonloc::ConcreteInt>(Offset))
return UnknownVal();
const TypedRegion* BaseRegion = 0;
const MemRegion* R = cast<loc::MemRegionVal>(Base).getRegion();
if (const SymbolicRegion* SR = dyn_cast<SymbolicRegion>(R)) {
SymbolRef Sym = SR->getSymbol();
BaseRegion = MRMgr.getTypedViewRegion(Sym->getType(getContext()), SR);
}
else
BaseRegion = cast<TypedRegion>(R);
// Pointer of any type can be cast and used as array base.
const ElementRegion *ElemR = dyn_cast<ElementRegion>(BaseRegion);
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 TypedViewRegion<AllocaRegion>.
//
// Offset might be unsigned. We have to convert it to signed ConcreteInt.
if (nonloc::ConcreteInt* CI = dyn_cast<nonloc::ConcreteInt>(&Offset)) {
const llvm::APSInt& OffI = CI->getValue();
if (OffI.isUnsigned()) {
llvm::APSInt Tmp = OffI;
Tmp.setIsSigned(true);
Offset = NonLoc::MakeVal(getBasicVals(), Tmp);
}
}
return loc::MemRegionVal(MRMgr.getElementRegion(elementType, Offset,
BaseRegion));
}
SVal BaseIdx = ElemR->getIndex();
if (!isa<nonloc::ConcreteInt>(BaseIdx))
return UnknownVal();
const llvm::APSInt& BaseIdxI = cast<nonloc::ConcreteInt>(BaseIdx).getValue();
const llvm::APSInt& OffI = cast<nonloc::ConcreteInt>(Offset).getValue();
assert(BaseIdxI.isSigned());
// FIXME: This appears to be the assumption of this code. We should review
// whether or not BaseIdxI.getBitWidth() < OffI.getBitWidth(). If it
// can't we need to put a comment here. If it can, we should handle it.
assert(BaseIdxI.getBitWidth() >= OffI.getBitWidth());
const TypedRegion *ArrayR = cast<TypedRegion>(ElemR->getSuperRegion());
SVal NewIdx;
if (OffI.isUnsigned() || OffI.getBitWidth() < BaseIdxI.getBitWidth()) {
// 'Offset' might be unsigned. We have to convert it to signed and
// possibly extend it.
llvm::APSInt Tmp = OffI;
if (OffI.getBitWidth() < BaseIdxI.getBitWidth())
Tmp.extend(BaseIdxI.getBitWidth());
Tmp.setIsSigned(true);
Tmp += BaseIdxI; // Compute the new offset.
NewIdx = NonLoc::MakeVal(getBasicVals(), Tmp);
}
else
NewIdx = nonloc::ConcreteInt(getBasicVals().getValue(BaseIdxI + OffI));
return loc::MemRegionVal(MRMgr.getElementRegion(elementType, NewIdx, ArrayR));
}
SVal RegionStoreManager::getSizeInElements(const GRState* St,
const MemRegion* R) {
if (const VarRegion* VR = dyn_cast<VarRegion>(R)) {
// Get the type of the variable.
QualType T = VR->getDesugaredRValueType(getContext());
// FIXME: Handle variable-length arrays.
if (isa<VariableArrayType>(T))
return UnknownVal();
if (const ConstantArrayType* CAT = dyn_cast<ConstantArrayType>(T)) {
// return the size as signed integer.
return NonLoc::MakeVal(getBasicVals(), CAT->getSize(), false);
}
GRStateRef state(St, StateMgr);
const QualType* CastTy = state.get<RegionCasts>(VR);
// If the VarRegion is cast to other type, compute the size with respect to
// that type.
if (CastTy) {
QualType EleTy =cast<PointerType>(CastTy->getTypePtr())->getPointeeType();
QualType VarTy = VR->getRValueType(getContext());
uint64_t EleSize = getContext().getTypeSize(EleTy);
uint64_t VarSize = getContext().getTypeSize(VarTy);
return NonLoc::MakeIntVal(getBasicVals(), VarSize / EleSize, false);
}
// Clients can use ordinary variables as if they were arrays. These
// essentially are arrays of size 1.
return NonLoc::MakeIntVal(getBasicVals(), 1, false);
}
if (const StringRegion* SR = dyn_cast<StringRegion>(R)) {
const StringLiteral* Str = SR->getStringLiteral();
// We intentionally made the size value signed because it participates in
// operations with signed indices.
return NonLoc::MakeIntVal(getBasicVals(), Str->getByteLength()+1, false);
}
if (const TypedViewRegion* ATR = dyn_cast<TypedViewRegion>(R)) {
#if 0
// FIXME: This logic doesn't really work, as we can have all sorts of
// weird cases. For example, this crashes on test case 'rdar-6442306-1.m'.
// The weird cases come in when arbitrary casting comes into play, violating
// any type-safe programming.
GRStateRef state(St, StateMgr);
// Get the size of the super region in bytes.
const SVal* Extent = state.get<RegionExtents>(ATR->getSuperRegion());
assert(Extent && "region extent not exist");
// Assume it's ConcreteInt for now.
llvm::APSInt SSize = cast<nonloc::ConcreteInt>(*Extent).getValue();
// Get the size of the element in bits.
QualType LvT = ATR->getLValueType(getContext());
QualType ElemTy = cast<PointerType>(LvT.getTypePtr())->getPointeeType();
uint64_t X = getContext().getTypeSize(ElemTy);
const llvm::APSInt& ESize = getBasicVals().getValue(X, SSize.getBitWidth(),
false);
// Calculate the number of elements.
// FIXME: What do we do with signed-ness problem? Shall we make all APSInts
// signed?
if (SSize.isUnsigned())
SSize.setIsSigned(true);
// FIXME: move this operation into BasicVals.
const llvm::APSInt S =
(SSize * getBasicVals().getValue(8, SSize.getBitWidth(), false)) / ESize;
return NonLoc::MakeVal(getBasicVals(), S);
#else
ATR = ATR;
return UnknownVal();
#endif
}
if (const FieldRegion* FR = dyn_cast<FieldRegion>(R)) {
// FIXME: Unsupported yet.
FR = 0;
return UnknownVal();
}
if (isa<SymbolicRegion>(R)) {
return UnknownVal();
}
if (isa<ElementRegion>(R)) {
return UnknownVal();
}
assert(0 && "Other regions are not supported yet.");
return UnknownVal();
}
/// ArrayToPointer - Emulates the "decay" of an array to a pointer
/// type. 'Array' represents the lvalue of the array being decayed
/// to a pointer, and the returned SVal represents the decayed
/// version of that lvalue (i.e., a pointer to the first element of
/// the array). This is called by GRExprEngine when evaluating casts
/// from arrays to pointers.
SVal RegionStoreManager::ArrayToPointer(Loc Array) {
if (!isa<loc::MemRegionVal>(Array))
return UnknownVal();
const MemRegion* R = cast<loc::MemRegionVal>(&Array)->getRegion();
const TypedRegion* ArrayR = dyn_cast<TypedRegion>(R);
if (!ArrayR)
return UnknownVal();
// Strip off typedefs from the ArrayRegion's RvalueType.
QualType T = ArrayR->getRValueType(getContext())->getDesugaredType();
ArrayType *AT = cast<ArrayType>(T);
T = AT->getElementType();
nonloc::ConcreteInt Idx(getBasicVals().getZeroWithPtrWidth(false));
ElementRegion* ER = MRMgr.getElementRegion(T, Idx, ArrayR);
return loc::MemRegionVal(ER);
}
RegionStoreManager::CastResult
RegionStoreManager::CastRegion(const GRState* state, const MemRegion* R,
QualType CastToTy) {
ASTContext& Ctx = StateMgr.getContext();
// We need to know the real type of CastToTy.
QualType ToTy = Ctx.getCanonicalType(CastToTy);
// Check cast to ObjCQualifiedID type.
if (isa<ObjCQualifiedIdType>(ToTy)) {
// FIXME: Record the type information aside.
return CastResult(state, R);
}
// CodeTextRegion should be cast to only function pointer type.
if (isa<CodeTextRegion>(R)) {
assert(CastToTy->isFunctionPointerType() || CastToTy->isBlockPointerType());
return CastResult(state, R);
}
// Assume we are casting from pointer to pointer. Other cases are handled
// elsewhere.
QualType PointeeTy = cast<PointerType>(ToTy.getTypePtr())->getPointeeType();
// Return the same region if the region types are compatible.
if (const TypedRegion* TR = dyn_cast<TypedRegion>(R)) {
QualType Ta = Ctx.getCanonicalType(TR->getLValueType(Ctx));
if (Ta == ToTy)
return CastResult(state, R);
}
// Process region cast according to the kind of the region being cast.
// FIXME: Need to handle arbitrary downcasts.
// FIXME: Handle the case where a TypedViewRegion (layering a SymbolicRegion
// or an AllocaRegion is cast to another view, thus causing the memory
// to be re-used for a different purpose.
if (isa<SymbolicRegion>(R) || isa<AllocaRegion>(R)) {
const MemRegion* ViewR = MRMgr.getTypedViewRegion(CastToTy, R);
return CastResult(AddRegionView(state, ViewR, R), ViewR);
}
// VarRegion, ElementRegion, and FieldRegion has an inherent type. Normally
// they should not be cast. We only layer an ElementRegion when the cast-to
// pointee type is of smaller size. In other cases, we return the original
// VarRegion.
if (isa<VarRegion>(R) || isa<ElementRegion>(R) || isa<FieldRegion>(R)
|| isa<ObjCIvarRegion>(R) || isa<CompoundLiteralRegion>(R)) {
// If the pointee type is incomplete, do not compute its size, and return
// the original region.
if (const RecordType *RT = dyn_cast<RecordType>(PointeeTy.getTypePtr())) {
const RecordDecl *D = RT->getDecl();
if (!D->getDefinition(getContext()))
return CastResult(state, R);
}
QualType ObjTy = cast<TypedRegion>(R)->getRValueType(getContext());
uint64_t PointeeTySize = getContext().getTypeSize(PointeeTy);
uint64_t ObjTySize = getContext().getTypeSize(ObjTy);
if (PointeeTySize > 0 && PointeeTySize < ObjTySize) {
// Record the cast type of the region.
state = setCastType(state, R, ToTy);
SVal Idx = ValMgr.makeZeroArrayIndex();
ElementRegion* ER = MRMgr.getElementRegion(PointeeTy, Idx, R);
return CastResult(state, ER);
} else
return CastResult(state, R);
}
if (isa<TypedViewRegion>(R)) {
const MemRegion* ViewR = MRMgr.getTypedViewRegion(CastToTy, R);
return CastResult(state, ViewR);
}
if (isa<ObjCObjectRegion>(R)) {
return CastResult(state, R);
}
assert(0 && "Unprocessed region.");
}
SVal RegionStoreManager::EvalBinOp(BinaryOperator::Opcode Op, Loc L, NonLoc R) {
// Assume the base location is MemRegionVal(ElementRegion).
if (!isa<loc::MemRegionVal>(L))
return UnknownVal();
const MemRegion* MR = cast<loc::MemRegionVal>(L).getRegion();
if (isa<SymbolicRegion>(MR))
return UnknownVal();
const TypedRegion* TR = cast<TypedRegion>(MR);
const ElementRegion* ER = dyn_cast<ElementRegion>(TR);
if (!ER) {
// If the region is not element region, create one with index 0. This can
// happen in the following example:
// char *p = foo();
// p += 3;
// Note that p binds to a TypedViewRegion(SymbolicRegion).
nonloc::ConcreteInt Idx(getBasicVals().getZeroWithPtrWidth(false));
ER = MRMgr.getElementRegion(TR->getRValueType(getContext()), Idx, TR);
}
SVal Idx = ER->getIndex();
nonloc::ConcreteInt* Base = dyn_cast<nonloc::ConcreteInt>(&Idx);
nonloc::ConcreteInt* Offset = dyn_cast<nonloc::ConcreteInt>(&R);
// Only support concrete integer indexes for now.
if (Base && Offset) {
// FIXME: For now, convert the signedness and bitwidth of offset in case
// they don't match. This can result from pointer arithmetic. In reality,
// we should figure out what are the proper semantics and implement them.
//
// This addresses the test case test/Analysis/ptr-arith.c
//
nonloc::ConcreteInt OffConverted(getBasicVals().Convert(Base->getValue(),
Offset->getValue()));
SVal NewIdx = Base->EvalBinOp(getBasicVals(), Op, OffConverted);
const MemRegion* NewER =
MRMgr.getElementRegion(ER->getElementType(), NewIdx,
cast<TypedRegion>(ER->getSuperRegion()));
return Loc::MakeVal(NewER);
}
return UnknownVal();
}
SVal RegionStoreManager::Retrieve(const GRState* St, Loc L, QualType T) {
assert(!isa<UnknownVal>(L) && "location unknown");
assert(!isa<UndefinedVal>(L) && "location undefined");
// FIXME: Is this even possible? Shouldn't this be treated as a null
// dereference at a higher level?
if (isa<loc::ConcreteInt>(L))
return UndefinedVal();
const MemRegion* MR = cast<loc::MemRegionVal>(L).getRegion();
// We return unknown for symbolic region for now. This might be improved.
// Example:
// void f(int* p) { int x = *p; }
if (isa<SymbolicRegion>(MR))
return UnknownVal();
// FIXME: Perhaps this method should just take a 'const MemRegion*' argument
// instead of 'Loc', and have the other Loc cases handled at a higher level.
const TypedRegion* R = cast<TypedRegion>(MR);
assert(R && "bad region");
// FIXME: We should eventually handle funny addressing. e.g.:
//
// int x = ...;
// int *p = &x;
// char *q = (char*) p;
// char c = *q; // returns the first byte of 'x'.
//
// Such funny addressing will occur due to layering of regions.
QualType RTy = R->getRValueType(getContext());
if (RTy->isStructureType())
return RetrieveStruct(St, R);
if (RTy->isArrayType())
return RetrieveArray(St, R);
// FIXME: handle Vector types.
if (RTy->isVectorType())
return UnknownVal();
RegionBindingsTy B = GetRegionBindings(St->getStore());
RegionBindingsTy::data_type* V = B.lookup(R);
// Check if the region has a binding.
if (V)
return *V;
GRStateRef state(St, StateMgr);
// Check if the region is in killset.
if (state.contains<RegionKills>(R))
return UnknownVal();
// If the region is an element or field, it may have a default value.
if (isa<ElementRegion>(R) || isa<FieldRegion>(R)) {
const MemRegion* SuperR = cast<SubRegion>(R)->getSuperRegion();
GRStateTrait<RegionDefaultValue>::lookup_type D =
state.get<RegionDefaultValue>(SuperR);
if (D)
return *D;
}
if (const ObjCIvarRegion *IVR = dyn_cast<ObjCIvarRegion>(R)) {
const MemRegion *SR = IVR->getSuperRegion();
// If the super region is 'self' then return the symbol representing
// the value of the ivar upon entry to the method.
if (SR == SelfRegion) {
// FIXME: Do we need to handle the case where the super region
// has a view? We want to canonicalize the bindings.
return ValMgr.getRValueSymbolVal(R);
}
// Otherwise, we need a new symbol. For now return Unknown.
return UnknownVal();
}
// The location does not have a bound value. This means that it has
// the value it had upon its creation and/or entry to the analyzed
// function/method. These are either symbolic values or 'undefined'.
// We treat function parameters as symbolic values.
if (const VarRegion* VR = dyn_cast<VarRegion>(R)) {
const VarDecl *VD = VR->getDecl();
if (VD == SelfDecl)
return loc::MemRegionVal(getSelfRegion(0));
if (isa<ParmVarDecl>(VD) || isa<ImplicitParamDecl>(VD) ||
VD->hasGlobalStorage()) {
QualType VTy = VD->getType();
if (Loc::IsLocType(VTy) || VTy->isIntegerType())
return ValMgr.getRValueSymbolVal(VR);
else
return UnknownVal();
}
}
if (MRMgr.onStack(R) || MRMgr.onHeap(R)) {
// All stack variables are considered to have undefined values
// upon creation. All heap allocated blocks are considered to
// have undefined values as well unless they are explicitly bound
// to specific values.
return UndefinedVal();
}
// All other integer values are symbolic.
if (Loc::IsLocType(RTy) || RTy->isIntegerType())
return ValMgr.getRValueSymbolVal(R);
else
return UnknownVal();
}
SVal RegionStoreManager::RetrieveStruct(const GRState* St,const TypedRegion* R){
// FIXME: Verify we want getRValueType instead of getLValueType.
QualType T = R->getRValueType(getContext());
assert(T->isStructureType());
const RecordType* RT = cast<RecordType>(T.getTypePtr());
RecordDecl* RD = RT->getDecl();
assert(RD->isDefinition());
llvm::ImmutableList<SVal> StructVal = getBasicVals().getEmptySValList();
std::vector<FieldDecl *> Fields(RD->field_begin(getContext()),
RD->field_end(getContext()));
for (std::vector<FieldDecl *>::reverse_iterator Field = Fields.rbegin(),
FieldEnd = Fields.rend();
Field != FieldEnd; ++Field) {
FieldRegion* FR = MRMgr.getFieldRegion(*Field, R);
QualType FTy = (*Field)->getType();
SVal FieldValue = Retrieve(St, loc::MemRegionVal(FR), FTy);
StructVal = getBasicVals().consVals(FieldValue, StructVal);
}
return NonLoc::MakeCompoundVal(T, StructVal, getBasicVals());
}
SVal RegionStoreManager::RetrieveArray(const GRState* St, const TypedRegion* R){
QualType T = R->getRValueType(getContext());
ConstantArrayType* CAT = cast<ConstantArrayType>(T.getTypePtr());
llvm::ImmutableList<SVal> ArrayVal = getBasicVals().getEmptySValList();
llvm::APSInt Size(CAT->getSize(), false);
llvm::APSInt i = getBasicVals().getValue(0, Size.getBitWidth(),
Size.isUnsigned());
for (; i < Size; ++i) {
SVal Idx = NonLoc::MakeVal(getBasicVals(), i);
ElementRegion* ER = MRMgr.getElementRegion(R->getRValueType(getContext()),
Idx, R);
QualType ETy = ER->getElementType();
SVal ElementVal = Retrieve(St, loc::MemRegionVal(ER), ETy);
ArrayVal = getBasicVals().consVals(ElementVal, ArrayVal);
}
return NonLoc::MakeCompoundVal(T, ArrayVal, getBasicVals());
}
const GRState* RegionStoreManager::Bind(const GRState* St, Loc L, SVal V) {
// If we get here, the location should be a region.
const MemRegion* R = cast<loc::MemRegionVal>(L).getRegion();
assert(R);
// Check if the region is a struct region.
if (const TypedRegion* TR = dyn_cast<TypedRegion>(R))
// FIXME: Verify we want getRValueType().
if (TR->getRValueType(getContext())->isStructureType())
return BindStruct(St, TR, V);
Store store = St->getStore();
RegionBindingsTy B = GetRegionBindings(store);
if (V.isUnknown()) {
// Remove the binding.
store = RBFactory.Remove(B, R).getRoot();
// Add the region to the killset.
GRStateRef state(St, StateMgr);
St = state.add<RegionKills>(R);
}
else
store = RBFactory.Add(B, R, V).getRoot();
return StateMgr.MakeStateWithStore(St, store);
}
Store RegionStoreManager::Remove(Store store, Loc L) {
const MemRegion* R = 0;
if (isa<loc::MemRegionVal>(L))
R = cast<loc::MemRegionVal>(L).getRegion();
if (R) {
RegionBindingsTy B = GetRegionBindings(store);
return RBFactory.Remove(B, R).getRoot();
}
return store;
}
const GRState* RegionStoreManager::BindDecl(const GRState* St,
const VarDecl* VD, SVal InitVal) {
QualType T = VD->getType();
VarRegion* VR = MRMgr.getVarRegion(VD);
if (T->isArrayType())
return BindArray(St, VR, InitVal);
if (T->isStructureType())
return BindStruct(St, VR, InitVal);
return Bind(St, Loc::MakeVal(VR), InitVal);
}
// FIXME: this method should be merged into Bind().
const GRState*
RegionStoreManager::BindCompoundLiteral(const GRState* St,
const CompoundLiteralExpr* CL, SVal V) {
CompoundLiteralRegion* R = MRMgr.getCompoundLiteralRegion(CL);
return Bind(St, loc::MemRegionVal(R), V);
}
const GRState* RegionStoreManager::setExtent(const GRState* St,
const MemRegion* R, SVal Extent) {
GRStateRef state(St, StateMgr);
return state.set<RegionExtents>(R, Extent);
}
static void UpdateLiveSymbols(SVal X, SymbolReaper& SymReaper) {
if (loc::MemRegionVal *XR = dyn_cast<loc::MemRegionVal>(&X)) {
const MemRegion *R = XR->getRegion();
while (R) {
if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R)) {
SymReaper.markLive(SR->getSymbol());
return;
}
if (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
R = SR->getSuperRegion();
continue;
}
break;
}
return;
}
for (SVal::symbol_iterator SI=X.symbol_begin(), SE=X.symbol_end();SI!=SE;++SI)
SymReaper.markLive(*SI);
}
Store RegionStoreManager::RemoveDeadBindings(const GRState* state, Stmt* Loc,
SymbolReaper& SymReaper,
llvm::SmallVectorImpl<const MemRegion*>& RegionRoots)
{
Store store = state->getStore();
RegionBindingsTy B = GetRegionBindings(store);
// Lazily constructed backmap from MemRegions to SubRegions.
typedef llvm::ImmutableSet<const MemRegion*> SubRegionsTy;
typedef llvm::ImmutableMap<const MemRegion*, SubRegionsTy> SubRegionsMapTy;
// FIXME: As a future optimization we can modifiy BumpPtrAllocator to have
// the ability to reuse memory. This way we can keep TmpAlloc around as
// an instance variable of RegionStoreManager (avoiding repeated malloc
// overhead).
llvm::BumpPtrAllocator TmpAlloc;
// Factory objects.
SubRegionsMapTy::Factory SubRegMapF(TmpAlloc);
SubRegionsTy::Factory SubRegF(TmpAlloc);
// The backmap from regions to subregions.
SubRegionsMapTy SubRegMap = SubRegMapF.GetEmptyMap();
// Do a pass over the regions in the store. For VarRegions we check if
// the variable is still live and if so add it to the list of live roots.
// For other regions we populate our region backmap.
llvm::SmallVector<const MemRegion*, 10> IntermediateRoots;
for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
IntermediateRoots.push_back(I.getKey());
}
while (!IntermediateRoots.empty()) {
const MemRegion* R = IntermediateRoots.back();
IntermediateRoots.pop_back();
if (const VarRegion* VR = dyn_cast<VarRegion>(R)) {
if (SymReaper.isLive(Loc, VR->getDecl()))
RegionRoots.push_back(VR); // This is a live "root".
}
else if (const SymbolicRegion* SR = dyn_cast<SymbolicRegion>(R)) {
if (SymReaper.isLive(SR->getSymbol()))
RegionRoots.push_back(SR);
}
else {
// Get the super region for R.
const MemRegion* SuperR = cast<SubRegion>(R)->getSuperRegion();
// Get the current set of subregions for SuperR.
const SubRegionsTy* SRptr = SubRegMap.lookup(SuperR);
SubRegionsTy SR = SRptr ? *SRptr : SubRegF.GetEmptySet();
// Add R to the subregions of SuperR.
SubRegMap = SubRegMapF.Add(SubRegMap, SuperR, SubRegF.Add(SR, R));
// Super region may be VarRegion or subregion of another VarRegion. Add it
// to the work list.
if (isa<SubRegion>(SuperR))
IntermediateRoots.push_back(SuperR);
}
}
// Process the worklist of RegionRoots. This performs a "mark-and-sweep"
// of the store. We want to find all live symbols and dead regions.
llvm::SmallPtrSet<const MemRegion*, 10> Marked;
while (!RegionRoots.empty()) {
// Dequeue the next region on the worklist.
const MemRegion* R = RegionRoots.back();
RegionRoots.pop_back();
// Check if we have already processed this region.
if (Marked.count(R)) continue;
// Mark this region as processed. This is needed for termination in case
// a region is referenced more than once.
Marked.insert(R);
// Mark the symbol for any live SymbolicRegion as "live". This means we
// should continue to track that symbol.
if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(R))
SymReaper.markLive(SymR->getSymbol());
// Get the data binding for R (if any).
RegionBindingsTy::data_type* Xptr = B.lookup(R);
if (Xptr) {
SVal X = *Xptr;
UpdateLiveSymbols(X, SymReaper); // Update the set of live symbols.
// If X is a region, then add it the RegionRoots.
if (loc::MemRegionVal* RegionX = dyn_cast<loc::MemRegionVal>(&X))
RegionRoots.push_back(RegionX->getRegion());
}
// Get the subregions of R. These are RegionRoots as well since they
// represent values that are also bound to R.
const SubRegionsTy* SRptr = SubRegMap.lookup(R);
if (!SRptr) continue;
SubRegionsTy SR = *SRptr;
for (SubRegionsTy::iterator I=SR.begin(), E=SR.end(); I!=E; ++I)
RegionRoots.push_back(*I);
}
// We have now scanned the store, marking reachable regions and symbols
// as live. We now remove all the regions that are dead from the store
// as well as update DSymbols with the set symbols that are now dead.
for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
const MemRegion* R = I.getKey();
// If this region live? Is so, none of its symbols are dead.
if (Marked.count(R))
continue;
// Remove this dead region from the store.
store = Remove(store, Loc::MakeVal(R));
// Mark all non-live symbols that this region references as dead.
if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(R))
SymReaper.maybeDead(SymR->getSymbol());
SVal X = I.getData();
SVal::symbol_iterator SI = X.symbol_begin(), SE = X.symbol_end();
for (; SI != SE; ++SI) SymReaper.maybeDead(*SI);
}
return store;
}
void RegionStoreManager::print(Store store, std::ostream& Out,
const char* nl, const char *sep) {
llvm::raw_os_ostream OS(Out);
RegionBindingsTy B = GetRegionBindings(store);
OS << "Store:" << nl;
for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
OS << ' '; I.getKey()->print(OS); OS << " : ";
I.getData().print(OS); OS << nl;
}
}
const GRState* RegionStoreManager::BindArray(const GRState* St,
const TypedRegion* R, SVal Init) {
// FIXME: Verify we should use getLValueType or getRValueType.
QualType T = R->getRValueType(getContext());
assert(T->isArrayType());
// When we are binding the whole array, it always has default value 0.
GRStateRef state(St, StateMgr);
St = state.set<RegionDefaultValue>(R, NonLoc::MakeIntVal(getBasicVals(), 0,
false));
ConstantArrayType* CAT = cast<ConstantArrayType>(T.getTypePtr());
llvm::APSInt Size(CAT->getSize(), false);
llvm::APSInt i = getBasicVals().getValue(0, Size.getBitWidth(),
Size.isUnsigned());
// Check if the init expr is a StringLiteral.
if (isa<loc::MemRegionVal>(Init)) {
const MemRegion* InitR = cast<loc::MemRegionVal>(Init).getRegion();
const StringLiteral* S = cast<StringRegion>(InitR)->getStringLiteral();
const char* str = S->getStrData();
unsigned len = S->getByteLength();
unsigned j = 0;
// Copy bytes from the string literal into the target array. Trailing bytes
// in the array that are not covered by the string literal are initialized
// to zero.
for (; i < Size; ++i, ++j) {
if (j >= len)
break;
SVal Idx = NonLoc::MakeVal(getBasicVals(), i);
ElementRegion* ER =
MRMgr.getElementRegion(cast<ArrayType>(T)->getElementType(),
Idx, R);
SVal V = NonLoc::MakeVal(getBasicVals(), str[j], sizeof(char)*8, true);
St = Bind(St, loc::MemRegionVal(ER), V);
}
return St;
}
nonloc::CompoundVal& CV = cast<nonloc::CompoundVal>(Init);
nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
for (; i < Size; ++i, ++VI) {
// The init list might be shorter than the array decl.
if (VI == VE)
break;
SVal Idx = NonLoc::MakeVal(getBasicVals(), i);
ElementRegion* ER =
MRMgr.getElementRegion(cast<ArrayType>(T)->getElementType(),
Idx, R);
if (CAT->getElementType()->isStructureType())
St = BindStruct(St, ER, *VI);
else
St = Bind(St, Loc::MakeVal(ER), *VI);
}
return St;
}
const GRState*
RegionStoreManager::BindStruct(const GRState* St, const TypedRegion* R, SVal V){
// FIXME: Verify that we should use getRValueType or getLValueType.
QualType T = R->getRValueType(getContext());
assert(T->isStructureType());
const RecordType* RT = T->getAsRecordType();
RecordDecl* RD = RT->getDecl();
if (!RD->isDefinition())
return St;
if (V.isUnknown())
return KillStruct(St, R);
nonloc::CompoundVal& CV = cast<nonloc::CompoundVal>(V);
nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
RecordDecl::field_iterator FI = RD->field_begin(getContext()),
FE = RD->field_end(getContext());
for (; FI != FE; ++FI, ++VI) {
// There may be fewer values than fields only when we are initializing a
// struct decl. In this case, mark the region as having default value.
if (VI == VE) {
GRStateRef state(St, StateMgr);
const NonLoc& Idx = NonLoc::MakeIntVal(getBasicVals(), 0, false);
St = state.set<RegionDefaultValue>(R, Idx);
break;
}
QualType FTy = (*FI)->getType();
FieldRegion* FR = MRMgr.getFieldRegion(*FI, R);
if (Loc::IsLocType(FTy) || FTy->isIntegerType())
St = Bind(St, Loc::MakeVal(FR), *VI);
else if (FTy->isArrayType())
St = BindArray(St, FR, *VI);
else if (FTy->isStructureType())
St = BindStruct(St, FR, *VI);
}
return St;
}
const GRState* RegionStoreManager::KillStruct(const GRState* St,
const TypedRegion* R){
GRStateRef state(St, StateMgr);
// Kill the struct region because it is assigned "unknown".
St = state.add<RegionKills>(R);
// Set the default value of the struct region to "unknown".
St = state.set<RegionDefaultValue>(R, UnknownVal());
Store store = St->getStore();
RegionBindingsTy B = GetRegionBindings(store);
// Remove all bindings for the subregions of the struct.
for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
const MemRegion* r = I.getKey();
if (const SubRegion* sr = dyn_cast<SubRegion>(r))
if (sr->isSubRegionOf(R))
store = Remove(store, Loc::MakeVal(sr));
// FIXME: Maybe we should also remove the bindings for the "views" of the
// subregions.
}
return StateMgr.MakeStateWithStore(St, store);
}
const GRState* RegionStoreManager::AddRegionView(const GRState* St,
const MemRegion* View,
const MemRegion* Base) {
GRStateRef state(St, StateMgr);
// First, retrieve the region view of the base region.
const RegionViews* d = state.get<RegionViewMap>(Base);
RegionViews L = d ? *d : RVFactory.GetEmptySet();
// Now add View to the region view.
L = RVFactory.Add(L, View);
// Create a new state with the new region view.
return state.set<RegionViewMap>(Base, L);
}
const GRState* RegionStoreManager::RemoveRegionView(const GRState* St,
const MemRegion* View,
const MemRegion* Base) {
GRStateRef state(St, StateMgr);
// Retrieve the region view of the base region.
const RegionViews* d = state.get<RegionViewMap>(Base);
// If the base region has no view, return.
if (!d)
return St;
// Remove the view.
RegionViews V = *d;
V = RVFactory.Remove(V, View);
return state.set<RegionViewMap>(Base, V);
}
const GRState* RegionStoreManager::setCastType(const GRState* St,
const MemRegion* R, QualType T) {
GRStateRef state(St, StateMgr);
return state.set<RegionCasts>(R, T);
}
Reference in New Issue View Git Blame Copy Permalink