llvm-project/clang/lib/Analysis/RegionStore.cpp

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//== 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/Analyses/LiveVariables.h"
#include "llvm/ADT/ImmutableMap.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Compiler.h"
using namespace clang;
typedef llvm::ImmutableMap<const MemRegion*, SVal> RegionBindingsTy;
namespace {
class VISIBILITY_HIDDEN RegionStoreManager : public StoreManager {
RegionBindingsTy::Factory RBFactory;
GRStateManager& StateMgr;
MemRegionManager MRMgr;
public:
RegionStoreManager(GRStateManager& mgr)
: StateMgr(mgr), MRMgr(StateMgr.getAllocator()) {}
virtual ~RegionStoreManager() {}
MemRegionManager& getRegionManager() { return MRMgr; }
// FIXME: Is this function necessary?
SVal GetRegionSVal(Store St, const MemRegion* R) {
return Retrieve(St, loc::MemRegionVal(R));
}
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 getLValueElement(const GRState* St, SVal Base, SVal Offset);
SVal ArrayToPointer(SVal Array);
SVal Retrieve(Store S, Loc L, QualType T = QualType());
Store Bind(Store St, Loc LV, SVal V);
Store Remove(Store store, Loc LV) {
// FIXME: Implement.
return store;
}
Store getInitialStore();
/// 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) {
assert (false && "Not implemented.");
return 0;
}
Store RemoveDeadBindings(Store store, Stmt* Loc, const LiveVariables& Live,
llvm::SmallVectorImpl<const MemRegion*>& RegionRoots,
LiveSymbolsTy& LSymbols, DeadSymbolsTy& DSymbols) {
// FIXME: Implement this.
return store;
}
Store AddDecl(Store store, const VarDecl* VD, Expr* Ex, SVal InitVal,
unsigned Count);
static inline RegionBindingsTy GetRegionBindings(Store store) {
return RegionBindingsTy(static_cast<const RegionBindingsTy::TreeTy*>(store));
}
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void print(Store store, std::ostream& Out, const char* nl, const char *sep);
void iterBindings(Store store, BindingsHandler& f) {
// FIXME: Implement.
}
private:
Loc getVarLoc(const VarDecl* VD) {
return loc::MemRegionVal(MRMgr.getVarRegion(VD));
}
Store InitializeArrayToUndefined(Store store, QualType T, MemRegion* BaseR);
Store InitializeStructToUndefined(Store store, QualType T, MemRegion* BaseR);
};
} // end anonymous namespace
StoreManager* clang::CreateRegionStoreManager(GRStateManager& StMgr) {
return new RegionStoreManager(StMgr);
}
SVal RegionStoreManager::getLValueVar(const GRState* St, const VarDecl* VD) {
return loc::MemRegionVal(MRMgr.getVarRegion(VD));
}
SVal RegionStoreManager::getLValueIvar(const GRState* St, const ObjCIvarDecl* D,
SVal Base) {
return UnknownVal();
}
SVal RegionStoreManager::getLValueField(const GRState* St, SVal Base,
const FieldDecl* 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();
break;
case loc::SymbolValKind:
BaseR = MRMgr.getSymbolicRegion(cast<loc::SymbolVal>(&BaseL)->getSymbol());
break;
case loc::GotoLabelKind:
case loc::FuncValKind:
// These are anormal cases. Flag an undefined value.
return UndefinedVal();
case loc::ConcreteIntKind:
case loc::StringLiteralValKind:
// 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("Unhandled Base.");
return Base;
}
return loc::MemRegionVal(MRMgr.getFieldRegion(D, BaseR));
}
SVal RegionStoreManager::getLValueElement(const GRState* St,
SVal Base, SVal Offset) {
if (Base.isUnknownOrUndef())
return Base;
loc::MemRegionVal& BaseL = cast<loc::MemRegionVal>(Base);
// We expect BaseR is an ElementRegion, not a base VarRegion.
const ElementRegion* ElemR = cast<ElementRegion>(BaseL.getRegion());
SVal Idx = ElemR->getIndex();
nonloc::ConcreteInt *CI1, *CI2;
// Only handle integer indices for now.
if ((CI1 = dyn_cast<nonloc::ConcreteInt>(&Idx)) &&
(CI2 = dyn_cast<nonloc::ConcreteInt>(&Offset))) {
SVal NewIdx = CI1->EvalBinOp(StateMgr.getBasicVals(), BinaryOperator::Add,
*CI2);
return loc::MemRegionVal(MRMgr.getElementRegion(NewIdx,
ElemR->getSuperRegion()));
}
return UnknownVal();
}
// Cast 'pointer to array' to 'pointer to the first element of array'.
SVal RegionStoreManager::ArrayToPointer(SVal Array) {
const MemRegion* ArrayR = cast<loc::MemRegionVal>(&Array)->getRegion();
const Decl* D = cast<DeclRegion>(ArrayR)->getDecl();
QualType ArrayTy;
if (const VarDecl* VD = dyn_cast<VarDecl>(D))
ArrayTy = VD->getType();
else if (const FieldDecl* FD = dyn_cast<FieldDecl>(D))
ArrayTy = FD->getType();
else
assert(0 && "unknown decl");
if (const ConstantArrayType* CAT =
dyn_cast<ConstantArrayType>(ArrayTy.getTypePtr())) {
BasicValueFactory& BasicVals = StateMgr.getBasicVals();
nonloc::ConcreteInt Idx(BasicVals.getValue(0, CAT->getSize().getBitWidth(),
false));
ElementRegion* ER = MRMgr.getElementRegion(Idx, ArrayR);
return loc::MemRegionVal(ER);
}
return Array;
}
SVal RegionStoreManager::Retrieve(Store S, Loc L, QualType T) {
assert(!isa<UnknownVal>(L) && "location unknown");
assert(!isa<UndefinedVal>(L) && "location undefined");
switch (L.getSubKind()) {
case loc::MemRegionKind: {
const MemRegion* R = cast<loc::MemRegionVal>(L).getRegion();
assert(R && "bad region");
RegionBindingsTy B(static_cast<const RegionBindingsTy::TreeTy*>(S));
RegionBindingsTy::data_type* V = B.lookup(R);
return V ? *V : UnknownVal();
}
case loc::SymbolValKind:
return UnknownVal();
case loc::ConcreteIntKind:
return UndefinedVal(); // As in BasicStoreManager.
case loc::FuncValKind:
return L;
case loc::StringLiteralValKind:
return UnknownVal();
default:
assert(false && "Invalid Location");
break;
}
}
Store RegionStoreManager::Bind(Store store, Loc LV, SVal V) {
assert(LV.getSubKind() == loc::MemRegionKind);
const MemRegion* R = cast<loc::MemRegionVal>(LV).getRegion();
if (!R)
return store;
RegionBindingsTy B = GetRegionBindings(store);
return V.isUnknown()
? RBFactory.Remove(B, R).getRoot()
: RBFactory.Add(B, R, V).getRoot();
}
Store RegionStoreManager::getInitialStore() {
typedef LiveVariables::AnalysisDataTy LVDataTy;
LVDataTy& D = StateMgr.getLiveVariables().getAnalysisData();
Store St = RBFactory.GetEmptyMap().getRoot();
for (LVDataTy::decl_iterator I=D.begin_decl(), E=D.end_decl(); I != E; ++I) {
NamedDecl* ND = const_cast<NamedDecl*>(I->first);
if (VarDecl* VD = dyn_cast<VarDecl>(ND)) {
// Punt on static variables for now.
if (VD->getStorageClass() == VarDecl::Static)
continue;
QualType T = VD->getType();
// Only handle pointers and integers for now.
if (Loc::IsLocType(T) || T->isIntegerType()) {
// Initialize globals and parameters to symbolic values.
// Initialize local variables to undefined.
SVal X = (VD->hasGlobalStorage() || isa<ParmVarDecl>(VD) ||
isa<ImplicitParamDecl>(VD))
? SVal::GetSymbolValue(StateMgr.getSymbolManager(), VD)
: UndefinedVal();
St = Bind(St, getVarLoc(VD), X);
}
}
}
return St;
}
Store RegionStoreManager::AddDecl(Store store,
const VarDecl* VD, Expr* Ex,
SVal InitVal, unsigned Count) {
BasicValueFactory& BasicVals = StateMgr.getBasicVals();
SymbolManager& SymMgr = StateMgr.getSymbolManager();
if (VD->hasGlobalStorage()) {
// Static global variables should not be visited here.
assert(!(VD->getStorageClass() == VarDecl::Static &&
VD->isFileVarDecl()));
// Process static variables.
if (VD->getStorageClass() == VarDecl::Static) {
if (!Ex) {
// Only handle pointer and integer static variables.
QualType T = VD->getType();
if (Loc::IsLocType(T))
store = Bind(store, getVarLoc(VD),
loc::ConcreteInt(BasicVals.getValue(0, T)));
else if (T->isIntegerType())
store = Bind(store, getVarLoc(VD),
loc::ConcreteInt(BasicVals.getValue(0, T)));
else
assert("ignore other types of variables");
} else {
store = Bind(store, getVarLoc(VD), InitVal);
}
}
} else {
// Process local variables.
QualType T = VD->getType();
VarRegion* VR = MRMgr.getVarRegion(VD);
if (Loc::IsLocType(T) || T->isIntegerType()) {
SVal V = Ex ? InitVal : UndefinedVal();
if (Ex && InitVal.isUnknown()) {
// "Conjured" symbols.
SymbolID Sym = SymMgr.getConjuredSymbol(Ex, Count);
V = Loc::IsLocType(Ex->getType())
? cast<SVal>(loc::SymbolVal(Sym))
: cast<SVal>(nonloc::SymbolVal(Sym));
}
store = Bind(store, loc::MemRegionVal(VR), V);
} else if (T->isArrayType()) {
store = InitializeArrayToUndefined(store, T, VR);
} else if (T->isStructureType()) {
store = InitializeStructToUndefined(store, T, VR);
}
}
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;
}
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}
Store RegionStoreManager::InitializeArrayToUndefined(Store store, QualType T,
MemRegion* BaseR) {
assert(T->isArrayType());
BasicValueFactory& BasicVals = StateMgr.getBasicVals();
// Only handle constant size array for now.
if (ConstantArrayType* CAT=dyn_cast<ConstantArrayType>(T.getTypePtr())) {
llvm::APInt Size = CAT->getSize();
for (llvm::APInt i = llvm::APInt::getNullValue(Size.getBitWidth());
i != Size; ++i) {
nonloc::ConcreteInt Idx(BasicVals.getValue(llvm::APSInt(i)));
ElementRegion* ER = MRMgr.getElementRegion(Idx, BaseR);
store = Bind(store, loc::MemRegionVal(ER), UndefinedVal());
}
}
return store;
}
Store RegionStoreManager::InitializeStructToUndefined(Store store, QualType T,
MemRegion* BaseR) {
const RecordType* RT = cast<RecordType>(T.getTypePtr());
RecordDecl* RD = RT->getDecl();
assert(RD->isDefinition());
for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
I != E; ++I) {
QualType FTy = (*I)->getType();
FieldRegion* FR = MRMgr.getFieldRegion(*I, BaseR);
if (Loc::IsLocType(FTy) || FTy->isIntegerType()) {
store = Bind(store, loc::MemRegionVal(FR), UndefinedVal());
} else if (FTy->isArrayType()) {
store = InitializeArrayToUndefined(store, FTy, FR);
} else if (FTy->isStructureType()) {
store = InitializeStructToUndefined(store, FTy, FR);
}
}
return store;
}