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llvm-project/clang/lib/StaticAnalyzer/Core/ProgramState.cpp

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//= ProgramState.cpp - Path-Sensitive "State" for tracking values --*- C++ -*--=
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements ProgramState and ProgramStateManager.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/CFG.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SubEngine.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/TaintManager.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace ento;
// Give the vtable for ConstraintManager somewhere to live.
// FIXME: Move this elsewhere.
ConstraintManager::~ConstraintManager() {}
namespace clang { namespace ento {
/// Increments the number of times this state is referenced.
void ProgramStateRetain(const ProgramState *state) {
++const_cast<ProgramState*>(state)->refCount;
}
/// Decrement the number of times this state is referenced.
void ProgramStateRelease(const ProgramState *state) {
assert(state->refCount > 0);
ProgramState *s = const_cast<ProgramState*>(state);
if (--s->refCount == 0) {
ProgramStateManager &Mgr = s->getStateManager();
Mgr.StateSet.RemoveNode(s);
s->~ProgramState();
Mgr.freeStates.push_back(s);
}
}
}}
ProgramState::ProgramState(ProgramStateManager *mgr, const Environment& env,
StoreRef st, GenericDataMap gdm)
: stateMgr(mgr),
Env(env),
store(st.getStore()),
GDM(gdm),
refCount(0) {
stateMgr->getStoreManager().incrementReferenceCount(store);
}
ProgramState::ProgramState(const ProgramState &RHS)
: llvm::FoldingSetNode(),
stateMgr(RHS.stateMgr),
Env(RHS.Env),
store(RHS.store),
GDM(RHS.GDM),
refCount(0) {
stateMgr->getStoreManager().incrementReferenceCount(store);
}
ProgramState::~ProgramState() {
if (store)
stateMgr->getStoreManager().decrementReferenceCount(store);
}
ProgramStateManager::~ProgramStateManager() {
for (GDMContextsTy::iterator I=GDMContexts.begin(), E=GDMContexts.end();
I!=E; ++I)
I->second.second(I->second.first);
}
ProgramStateRef
ProgramStateManager::removeDeadBindings(ProgramStateRef state,
const StackFrameContext *LCtx,
SymbolReaper& SymReaper) {
// This code essentially performs a "mark-and-sweep" of the VariableBindings.
// The roots are any Block-level exprs and Decls that our liveness algorithm
// tells us are live. We then see what Decls they may reference, and keep
// those around. This code more than likely can be made faster, and the
// frequency of which this method is called should be experimented with
// for optimum performance.
ProgramState NewState = *state;
NewState.Env = EnvMgr.removeDeadBindings(NewState.Env, SymReaper, state);
// Clean up the store.
StoreRef newStore = StoreMgr->removeDeadBindings(NewState.getStore(), LCtx,
SymReaper);
NewState.setStore(newStore);
SymReaper.setReapedStore(newStore);
return getPersistentState(NewState);
}
ProgramStateRef ProgramStateManager::MarshalState(ProgramStateRef state,
const StackFrameContext *InitLoc) {
// make up an empty state for now.
ProgramState State(this,
EnvMgr.getInitialEnvironment(),
StoreMgr->getInitialStore(InitLoc),
GDMFactory.getEmptyMap());
return getPersistentState(State);
}
ProgramStateRef ProgramState::bindCompoundLiteral(const CompoundLiteralExpr *CL,
const LocationContext *LC,
SVal V) const {
const StoreRef &newStore =
getStateManager().StoreMgr->BindCompoundLiteral(getStore(), CL, LC, V);
return makeWithStore(newStore);
}
ProgramStateRef ProgramState::bindDecl(const VarRegion* VR, SVal IVal) const {
const StoreRef &newStore =
getStateManager().StoreMgr->BindDecl(getStore(), VR, IVal);
return makeWithStore(newStore);
}
ProgramStateRef ProgramState::bindDeclWithNoInit(const VarRegion* VR) const {
const StoreRef &newStore =
getStateManager().StoreMgr->BindDeclWithNoInit(getStore(), VR);
return makeWithStore(newStore);
}
ProgramStateRef ProgramState::bindLoc(Loc LV, SVal V) const {
ProgramStateManager &Mgr = getStateManager();
ProgramStateRef newState = makeWithStore(Mgr.StoreMgr->Bind(getStore(),
LV, V));
const MemRegion *MR = LV.getAsRegion();
if (MR && Mgr.getOwningEngine())
return Mgr.getOwningEngine()->processRegionChange(newState, MR);
return newState;
}
ProgramStateRef ProgramState::bindDefault(SVal loc, SVal V) const {
ProgramStateManager &Mgr = getStateManager();
const MemRegion *R = cast<loc::MemRegionVal>(loc).getRegion();
const StoreRef &newStore = Mgr.StoreMgr->BindDefault(getStore(), R, V);
ProgramStateRef new_state = makeWithStore(newStore);
return Mgr.getOwningEngine() ?
Mgr.getOwningEngine()->processRegionChange(new_state, R) :
new_state;
}
ProgramStateRef
ProgramState::invalidateRegions(ArrayRef<const MemRegion *> Regions,
const Expr *E, unsigned Count,
const LocationContext *LCtx,
StoreManager::InvalidatedSymbols *IS,
const CallOrObjCMessage *Call) const {
if (!IS) {
StoreManager::InvalidatedSymbols invalidated;
return invalidateRegionsImpl(Regions, E, Count, LCtx,
invalidated, Call);
}
return invalidateRegionsImpl(Regions, E, Count, LCtx, *IS, Call);
}
ProgramStateRef
ProgramState::invalidateRegionsImpl(ArrayRef<const MemRegion *> Regions,
const Expr *E, unsigned Count,
const LocationContext *LCtx,
StoreManager::InvalidatedSymbols &IS,
const CallOrObjCMessage *Call) const {
ProgramStateManager &Mgr = getStateManager();
SubEngine* Eng = Mgr.getOwningEngine();
if (Eng && Eng->wantsRegionChangeUpdate(this)) {
StoreManager::InvalidatedRegions Invalidated;
const StoreRef &newStore
= Mgr.StoreMgr->invalidateRegions(getStore(), Regions, E, Count, LCtx, IS,
Call, &Invalidated);
ProgramStateRef newState = makeWithStore(newStore);
return Eng->processRegionChanges(newState, &IS, Regions, Invalidated, Call);
}
const StoreRef &newStore =
Mgr.StoreMgr->invalidateRegions(getStore(), Regions, E, Count, LCtx, IS,
Call, NULL);
return makeWithStore(newStore);
}
ProgramStateRef ProgramState::unbindLoc(Loc LV) const {
assert(!isa<loc::MemRegionVal>(LV) && "Use invalidateRegion instead.");
Store OldStore = getStore();
const StoreRef &newStore = getStateManager().StoreMgr->Remove(OldStore, LV);
if (newStore.getStore() == OldStore)
return this;
return makeWithStore(newStore);
}
ProgramStateRef
ProgramState::enterStackFrame(const LocationContext *callerCtx,
const StackFrameContext *calleeCtx) const {
const StoreRef &new_store =
getStateManager().StoreMgr->enterStackFrame(this, callerCtx, calleeCtx);
return makeWithStore(new_store);
}
SVal ProgramState::getSValAsScalarOrLoc(const MemRegion *R) const {
// We only want to do fetches from regions that we can actually bind
// values. For example, SymbolicRegions of type 'id<...>' cannot
// have direct bindings (but their can be bindings on their subregions).
if (!R->isBoundable())
return UnknownVal();
if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
QualType T = TR->getValueType();
if (Loc::isLocType(T) || T->isIntegerType())
return getSVal(R);
}
return UnknownVal();
}
SVal ProgramState::getSVal(Loc location, QualType T) const {
SVal V = getRawSVal(cast<Loc>(location), T);
// If 'V' is a symbolic value that is *perfectly* constrained to
// be a constant value, use that value instead to lessen the burden
// on later analysis stages (so we have less symbolic values to reason
// about).
if (!T.isNull()) {
if (SymbolRef sym = V.getAsSymbol()) {
if (const llvm::APSInt *Int = getSymVal(sym)) {
// FIXME: Because we don't correctly model (yet) sign-extension
// and truncation of symbolic values, we need to convert
// the integer value to the correct signedness and bitwidth.
//
// This shows up in the following:
//
// char foo();
// unsigned x = foo();
// if (x == 54)
// ...
//
// The symbolic value stored to 'x' is actually the conjured
// symbol for the call to foo(); the type of that symbol is 'char',
// not unsigned.
const llvm::APSInt &NewV = getBasicVals().Convert(T, *Int);
if (isa<Loc>(V))
return loc::ConcreteInt(NewV);
else
return nonloc::ConcreteInt(NewV);
}
}
}
return V;
}
ProgramStateRef ProgramState::BindExpr(const Stmt *S,
const LocationContext *LCtx,
SVal V, bool Invalidate) const{
Environment NewEnv =
getStateManager().EnvMgr.bindExpr(Env, EnvironmentEntry(S, LCtx), V,
Invalidate);
if (NewEnv == Env)
return this;
ProgramState NewSt = *this;
NewSt.Env = NewEnv;
return getStateManager().getPersistentState(NewSt);
}
ProgramStateRef
ProgramState::bindExprAndLocation(const Stmt *S, const LocationContext *LCtx,
SVal location,
SVal V) const {
Environment NewEnv =
getStateManager().EnvMgr.bindExprAndLocation(Env,
EnvironmentEntry(S, LCtx),
location, V);
if (NewEnv == Env)
return this;
ProgramState NewSt = *this;
NewSt.Env = NewEnv;
return getStateManager().getPersistentState(NewSt);
}
ProgramStateRef ProgramState::assumeInBound(DefinedOrUnknownSVal Idx,
DefinedOrUnknownSVal UpperBound,
bool Assumption,
QualType indexTy) const {
if (Idx.isUnknown() || UpperBound.isUnknown())
return this;
// Build an expression for 0 <= Idx < UpperBound.
// This is the same as Idx + MIN < UpperBound + MIN, if overflow is allowed.
// FIXME: This should probably be part of SValBuilder.
ProgramStateManager &SM = getStateManager();
SValBuilder &svalBuilder = SM.getSValBuilder();
ASTContext &Ctx = svalBuilder.getContext();
// Get the offset: the minimum value of the array index type.
BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
// FIXME: This should be using ValueManager::ArrayindexTy...somehow.
if (indexTy.isNull())
indexTy = Ctx.IntTy;
nonloc::ConcreteInt Min(BVF.getMinValue(indexTy));
// Adjust the index.
SVal newIdx = svalBuilder.evalBinOpNN(this, BO_Add,
cast<NonLoc>(Idx), Min, indexTy);
if (newIdx.isUnknownOrUndef())
return this;
// Adjust the upper bound.
SVal newBound =
svalBuilder.evalBinOpNN(this, BO_Add, cast<NonLoc>(UpperBound),
Min, indexTy);
if (newBound.isUnknownOrUndef())
return this;
// Build the actual comparison.
SVal inBound = svalBuilder.evalBinOpNN(this, BO_LT,
cast<NonLoc>(newIdx), cast<NonLoc>(newBound),
Ctx.IntTy);
if (inBound.isUnknownOrUndef())
return this;
// Finally, let the constraint manager take care of it.
ConstraintManager &CM = SM.getConstraintManager();
return CM.assume(this, cast<DefinedSVal>(inBound), Assumption);
}
ProgramStateRef ProgramStateManager::getInitialState(const LocationContext *InitLoc) {
ProgramState State(this,
EnvMgr.getInitialEnvironment(),
StoreMgr->getInitialStore(InitLoc),
GDMFactory.getEmptyMap());
return getPersistentState(State);
}
ProgramStateRef ProgramStateManager::getPersistentStateWithGDM(
ProgramStateRef FromState,
ProgramStateRef GDMState) {
ProgramState NewState(*FromState);
NewState.GDM = GDMState->GDM;
return getPersistentState(NewState);
}
ProgramStateRef ProgramStateManager::getPersistentState(ProgramState &State) {
llvm::FoldingSetNodeID ID;
State.Profile(ID);
void *InsertPos;
if (ProgramState *I = StateSet.FindNodeOrInsertPos(ID, InsertPos))
return I;
ProgramState *newState = 0;
if (!freeStates.empty()) {
newState = freeStates.back();
freeStates.pop_back();
}
else {
newState = (ProgramState*) Alloc.Allocate<ProgramState>();
}
new (newState) ProgramState(State);
StateSet.InsertNode(newState, InsertPos);
return newState;
}
ProgramStateRef ProgramState::makeWithStore(const StoreRef &store) const {
ProgramState NewSt(*this);
NewSt.setStore(store);
return getStateManager().getPersistentState(NewSt);
}
void ProgramState::setStore(const StoreRef &newStore) {
Store newStoreStore = newStore.getStore();
if (newStoreStore)
stateMgr->getStoreManager().incrementReferenceCount(newStoreStore);
if (store)
stateMgr->getStoreManager().decrementReferenceCount(store);
store = newStoreStore;
}
//===----------------------------------------------------------------------===//
// State pretty-printing.
//===----------------------------------------------------------------------===//
void ProgramState::print(raw_ostream &Out,
const char *NL, const char *Sep) const {
// Print the store.
ProgramStateManager &Mgr = getStateManager();
Mgr.getStoreManager().print(getStore(), Out, NL, Sep);
// Print out the environment.
Env.print(Out, NL, Sep);
// Print out the constraints.
Mgr.getConstraintManager().print(this, Out, NL, Sep);
// Print checker-specific data.
Mgr.getOwningEngine()->printState(Out, this, NL, Sep);
}
void ProgramState::printDOT(raw_ostream &Out) const {
print(Out, "\\l", "\\|");
}
void ProgramState::dump() const {
print(llvm::errs());
}
void ProgramState::printTaint(raw_ostream &Out,
const char *NL, const char *Sep) const {
TaintMapImpl TM = get<TaintMap>();
if (!TM.isEmpty())
Out <<"Tainted Symbols:" << NL;
for (TaintMapImpl::iterator I = TM.begin(), E = TM.end(); I != E; ++I) {
Out << I->first << " : " << I->second << NL;
}
}
void ProgramState::dumpTaint() const {
printTaint(llvm::errs());
}
//===----------------------------------------------------------------------===//
// Generic Data Map.
//===----------------------------------------------------------------------===//
void *const* ProgramState::FindGDM(void *K) const {
return GDM.lookup(K);
}
void*
ProgramStateManager::FindGDMContext(void *K,
void *(*CreateContext)(llvm::BumpPtrAllocator&),
void (*DeleteContext)(void*)) {
std::pair<void*, void (*)(void*)>& p = GDMContexts[K];
if (!p.first) {
p.first = CreateContext(Alloc);
p.second = DeleteContext;
}
return p.first;
}
ProgramStateRef ProgramStateManager::addGDM(ProgramStateRef St, void *Key, void *Data){
ProgramState::GenericDataMap M1 = St->getGDM();
ProgramState::GenericDataMap M2 = GDMFactory.add(M1, Key, Data);
if (M1 == M2)
return St;
ProgramState NewSt = *St;
NewSt.GDM = M2;
return getPersistentState(NewSt);
}
ProgramStateRef ProgramStateManager::removeGDM(ProgramStateRef state, void *Key) {
ProgramState::GenericDataMap OldM = state->getGDM();
ProgramState::GenericDataMap NewM = GDMFactory.remove(OldM, Key);
if (NewM == OldM)
return state;
ProgramState NewState = *state;
NewState.GDM = NewM;
return getPersistentState(NewState);
}
void ScanReachableSymbols::anchor() { }
bool ScanReachableSymbols::scan(nonloc::CompoundVal val) {
for (nonloc::CompoundVal::iterator I=val.begin(), E=val.end(); I!=E; ++I)
if (!scan(*I))
return false;
return true;
}
bool ScanReachableSymbols::scan(const SymExpr *sym) {
unsigned &isVisited = visited[sym];
if (isVisited)
return true;
isVisited = 1;
if (!visitor.VisitSymbol(sym))
return false;
// TODO: should be rewritten using SymExpr::symbol_iterator.
switch (sym->getKind()) {
case SymExpr::RegionValueKind:
case SymExpr::ConjuredKind:
case SymExpr::DerivedKind:
case SymExpr::ExtentKind:
case SymExpr::MetadataKind:
break;
case SymExpr::CastSymbolKind:
return scan(cast<SymbolCast>(sym)->getOperand());
case SymExpr::SymIntKind:
return scan(cast<SymIntExpr>(sym)->getLHS());
case SymExpr::IntSymKind:
return scan(cast<IntSymExpr>(sym)->getRHS());
case SymExpr::SymSymKind: {
const SymSymExpr *x = cast<SymSymExpr>(sym);
return scan(x->getLHS()) && scan(x->getRHS());
}
}
return true;
}
bool ScanReachableSymbols::scan(SVal val) {
if (loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(&val))
return scan(X->getRegion());
if (nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(&val))
return scan(X->getLoc());
if (SymbolRef Sym = val.getAsSymbol())
return scan(Sym);
if (const SymExpr *Sym = val.getAsSymbolicExpression())
return scan(Sym);
if (nonloc::CompoundVal *X = dyn_cast<nonloc::CompoundVal>(&val))
return scan(*X);
return true;
}
bool ScanReachableSymbols::scan(const MemRegion *R) {
if (isa<MemSpaceRegion>(R))
return true;
unsigned &isVisited = visited[R];
if (isVisited)
return true;
isVisited = 1;
if (!visitor.VisitMemRegion(R))
return false;
// If this is a symbolic region, visit the symbol for the region.
if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
if (!visitor.VisitSymbol(SR->getSymbol()))
return false;
// If this is a subregion, also visit the parent regions.
if (const SubRegion *SR = dyn_cast<SubRegion>(R))
if (!scan(SR->getSuperRegion()))
return false;
// Now look at the binding to this region (if any).
if (!scan(state->getSValAsScalarOrLoc(R)))
return false;
// Now look at the subregions.
if (!SRM.get())
SRM.reset(state->getStateManager().getStoreManager().
getSubRegionMap(state->getStore()));
return SRM->iterSubRegions(R, *this);
}
bool ProgramState::scanReachableSymbols(SVal val, SymbolVisitor& visitor) const {
ScanReachableSymbols S(this, visitor);
return S.scan(val);
}
bool ProgramState::scanReachableSymbols(const SVal *I, const SVal *E,
SymbolVisitor &visitor) const {
ScanReachableSymbols S(this, visitor);
for ( ; I != E; ++I) {
if (!S.scan(*I))
return false;
}
return true;
}
bool ProgramState::scanReachableSymbols(const MemRegion * const *I,
const MemRegion * const *E,
SymbolVisitor &visitor) const {
ScanReachableSymbols S(this, visitor);
for ( ; I != E; ++I) {
if (!S.scan(*I))
return false;
}
return true;
}
ProgramStateRef ProgramState::addTaint(const Stmt *S,
const LocationContext *LCtx,
TaintTagType Kind) const {
if (const Expr *E = dyn_cast_or_null<Expr>(S))
S = E->IgnoreParens();
SymbolRef Sym = getSVal(S, LCtx).getAsSymbol();
if (Sym)
return addTaint(Sym, Kind);
const MemRegion *R = getSVal(S, LCtx).getAsRegion();
addTaint(R, Kind);
// Cannot add taint, so just return the state.
return this;
}
ProgramStateRef ProgramState::addTaint(const MemRegion *R,
TaintTagType Kind) const {
if (const SymbolicRegion *SR = dyn_cast_or_null<SymbolicRegion>(R))
return addTaint(SR->getSymbol(), Kind);
return this;
}
ProgramStateRef ProgramState::addTaint(SymbolRef Sym,
TaintTagType Kind) const {
// If this is a symbol cast, remove the cast before adding the taint. Taint
// is cast agnostic.
while (const SymbolCast *SC = dyn_cast<SymbolCast>(Sym))
Sym = SC->getOperand();
ProgramStateRef NewState = set<TaintMap>(Sym, Kind);
assert(NewState);
return NewState;
}
bool ProgramState::isTainted(const Stmt *S, const LocationContext *LCtx,
TaintTagType Kind) const {
if (const Expr *E = dyn_cast_or_null<Expr>(S))
S = E->IgnoreParens();
SVal val = getSVal(S, LCtx);
return isTainted(val, Kind);
}
bool ProgramState::isTainted(SVal V, TaintTagType Kind) const {
if (const SymExpr *Sym = V.getAsSymExpr())
return isTainted(Sym, Kind);
if (const MemRegion *Reg = V.getAsRegion())
return isTainted(Reg, Kind);
return false;
}
bool ProgramState::isTainted(const MemRegion *Reg, TaintTagType K) const {
if (!Reg)
return false;
// Element region (array element) is tainted if either the base or the offset
// are tainted.
if (const ElementRegion *ER = dyn_cast<ElementRegion>(Reg))
return isTainted(ER->getSuperRegion(), K) || isTainted(ER->getIndex(), K);
if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(Reg))
return isTainted(SR->getSymbol(), K);
if (const SubRegion *ER = dyn_cast<SubRegion>(Reg))
return isTainted(ER->getSuperRegion(), K);
return false;
}
bool ProgramState::isTainted(SymbolRef Sym, TaintTagType Kind) const {
if (!Sym)
return false;
// Traverse all the symbols this symbol depends on to see if any are tainted.
bool Tainted = false;
for (SymExpr::symbol_iterator SI = Sym->symbol_begin(), SE =Sym->symbol_end();
SI != SE; ++SI) {
assert(isa<SymbolData>(*SI));
const TaintTagType *Tag = get<TaintMap>(*SI);
Tainted = (Tag && *Tag == Kind);
// If this is a SymbolDerived with a tainted parent, it's also tainted.
if (const SymbolDerived *SD = dyn_cast<SymbolDerived>(*SI))
Tainted = Tainted || isTainted(SD->getParentSymbol(), Kind);
// If memory region is tainted, data is also tainted.
if (const SymbolRegionValue *SRV = dyn_cast<SymbolRegionValue>(*SI))
Tainted = Tainted || isTainted(SRV->getRegion(), Kind);
// If If this is a SymbolCast from a tainted value, it's also tainted.
if (const SymbolCast *SC = dyn_cast<SymbolCast>(*SI))
Tainted = Tainted || isTainted(SC->getOperand(), Kind);
if (Tainted)
return true;
}
return Tainted;
}
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