ProgramState.cpp revision 6bcf27bb9a4b5c3f79cb44c0e4654a6d7619ad89 
1//= ProgramState.cpp - Path-Sensitive "State" for tracking values --*- C++ -*--=
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements ProgramState and ProgramStateManager.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
15#include "clang/Analysis/CFG.h"
16#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/SubEngine.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/TaintManager.h"
20#include "llvm/Support/raw_ostream.h"
21
22using namespace clang;
23using namespace ento;
24
25namespace clang { namespace  ento {
26/// Increments the number of times this state is referenced.
27
28void ProgramStateRetain(const ProgramState *state) {
29  ++const_cast<ProgramState*>(state)->refCount;
30}
31
32/// Decrement the number of times this state is referenced.
33void ProgramStateRelease(const ProgramState *state) {
34  assert(state->refCount > 0);
35  ProgramState *s = const_cast<ProgramState*>(state);
36  if (--s->refCount == 0) {
37    ProgramStateManager &Mgr = s->getStateManager();
38    Mgr.StateSet.RemoveNode(s);
39    s->~ProgramState();
40    Mgr.freeStates.push_back(s);
41  }
42}
43}}
44
45ProgramState::ProgramState(ProgramStateManager *mgr, const Environment& env,
46                 StoreRef st, GenericDataMap gdm)
47  : stateMgr(mgr),
48    Env(env),
49    store(st.getStore()),
50    GDM(gdm),
51    refCount(0) {
52  stateMgr->getStoreManager().incrementReferenceCount(store);
53}
54
55ProgramState::ProgramState(const ProgramState &RHS)
56    : llvm::FoldingSetNode(),
57      stateMgr(RHS.stateMgr),
58      Env(RHS.Env),
59      store(RHS.store),
60      GDM(RHS.GDM),
61      refCount(0) {
62  stateMgr->getStoreManager().incrementReferenceCount(store);
63}
64
65ProgramState::~ProgramState() {
66  if (store)
67    stateMgr->getStoreManager().decrementReferenceCount(store);
68}
69
70ProgramStateManager::ProgramStateManager(ASTContext &Ctx,
71                                         StoreManagerCreator CreateSMgr,
72                                         ConstraintManagerCreator CreateCMgr,
73                                         llvm::BumpPtrAllocator &alloc,
74                                         SubEngine *SubEng)
75  : Eng(SubEng), EnvMgr(alloc), GDMFactory(alloc),
76    svalBuilder(createSimpleSValBuilder(alloc, Ctx, *this)),
77    CallEventMgr(new CallEventManager(alloc)), Alloc(alloc) {
78  StoreMgr.reset((*CreateSMgr)(*this));
79  ConstraintMgr.reset((*CreateCMgr)(*this, SubEng));
80}
81
82
83ProgramStateManager::~ProgramStateManager() {
84  for (GDMContextsTy::iterator I=GDMContexts.begin(), E=GDMContexts.end();
85       I!=E; ++I)
86    I->second.second(I->second.first);
87}
88
89ProgramStateRef
90ProgramStateManager::removeDeadBindings(ProgramStateRef state,
91                                   const StackFrameContext *LCtx,
92                                   SymbolReaper& SymReaper) {
93
94  // This code essentially performs a "mark-and-sweep" of the VariableBindings.
95  // The roots are any Block-level exprs and Decls that our liveness algorithm
96  // tells us are live.  We then see what Decls they may reference, and keep
97  // those around.  This code more than likely can be made faster, and the
98  // frequency of which this method is called should be experimented with
99  // for optimum performance.
100  ProgramState NewState = *state;
101
102  NewState.Env = EnvMgr.removeDeadBindings(NewState.Env, SymReaper, state);
103
104  // Clean up the store.
105  StoreRef newStore = StoreMgr->removeDeadBindings(NewState.getStore(), LCtx,
106                                                   SymReaper);
107  NewState.setStore(newStore);
108  SymReaper.setReapedStore(newStore);
109
110  ProgramStateRef Result = getPersistentState(NewState);
111  return ConstraintMgr->removeDeadBindings(Result, SymReaper);
112}
113
114ProgramStateRef ProgramState::bindLoc(Loc LV, SVal V, bool notifyChanges) const {
115  ProgramStateManager &Mgr = getStateManager();
116  ProgramStateRef newState = makeWithStore(Mgr.StoreMgr->Bind(getStore(),
117                                                             LV, V));
118  const MemRegion *MR = LV.getAsRegion();
119  if (MR && Mgr.getOwningEngine() && notifyChanges)
120    return Mgr.getOwningEngine()->processRegionChange(newState, MR);
121
122  return newState;
123}
124
125ProgramStateRef ProgramState::bindDefault(SVal loc, SVal V) const {
126  ProgramStateManager &Mgr = getStateManager();
127  const MemRegion *R = loc.castAs<loc::MemRegionVal>().getRegion();
128  const StoreRef &newStore = Mgr.StoreMgr->BindDefault(getStore(), R, V);
129  ProgramStateRef new_state = makeWithStore(newStore);
130  return Mgr.getOwningEngine() ?
131           Mgr.getOwningEngine()->processRegionChange(new_state, R) :
132           new_state;
133}
134
135typedef ArrayRef<const MemRegion *> RegionList;
136typedef ArrayRef<SVal> ValueList;
137
138ProgramStateRef
139ProgramState::invalidateRegions(RegionList Regions,
140                             const Expr *E, unsigned Count,
141                             const LocationContext *LCtx,
142                             bool CausedByPointerEscape,
143                             InvalidatedSymbols *IS,
144                             const CallEvent *Call,
145                             RegionAndSymbolInvalidationTraits *ITraits) const {
146  SmallVector<SVal, 8> Values;
147  for (RegionList::const_iterator I = Regions.begin(),
148                                  End = Regions.end(); I != End; ++I)
149    Values.push_back(loc::MemRegionVal(*I));
150
151  return invalidateRegionsImpl(Values, E, Count, LCtx, CausedByPointerEscape,
152                               IS, ITraits, Call);
153}
154
155ProgramStateRef
156ProgramState::invalidateRegions(ValueList Values,
157                             const Expr *E, unsigned Count,
158                             const LocationContext *LCtx,
159                             bool CausedByPointerEscape,
160                             InvalidatedSymbols *IS,
161                             const CallEvent *Call,
162                             RegionAndSymbolInvalidationTraits *ITraits) const {
163
164  return invalidateRegionsImpl(Values, E, Count, LCtx, CausedByPointerEscape,
165                               IS, ITraits, Call);
166}
167
168ProgramStateRef
169ProgramState::invalidateRegionsImpl(ValueList Values,
170                                    const Expr *E, unsigned Count,
171                                    const LocationContext *LCtx,
172                                    bool CausedByPointerEscape,
173                                    InvalidatedSymbols *IS,
174                                    RegionAndSymbolInvalidationTraits *ITraits,
175                                    const CallEvent *Call) const {
176  ProgramStateManager &Mgr = getStateManager();
177  SubEngine* Eng = Mgr.getOwningEngine();
178
179  InvalidatedSymbols Invalidated;
180  if (!IS)
181    IS = &Invalidated;
182
183  RegionAndSymbolInvalidationTraits ITraitsLocal;
184  if (!ITraits)
185    ITraits = &ITraitsLocal;
186
187  if (Eng) {
188    StoreManager::InvalidatedRegions TopLevelInvalidated;
189    StoreManager::InvalidatedRegions Invalidated;
190    const StoreRef &newStore
191    = Mgr.StoreMgr->invalidateRegions(getStore(), Values, E, Count, LCtx, Call,
192                                      *IS, *ITraits, &TopLevelInvalidated,
193                                      &Invalidated);
194
195    ProgramStateRef newState = makeWithStore(newStore);
196
197    if (CausedByPointerEscape) {
198      newState = Eng->notifyCheckersOfPointerEscape(newState, IS,
199                                                    TopLevelInvalidated,
200                                                    Invalidated, Call,
201                                                    *ITraits);
202    }
203
204    return Eng->processRegionChanges(newState, IS, TopLevelInvalidated,
205                                     Invalidated, Call);
206  }
207
208  const StoreRef &newStore =
209  Mgr.StoreMgr->invalidateRegions(getStore(), Values, E, Count, LCtx, Call,
210                                  *IS, *ITraits, nullptr, nullptr);
211  return makeWithStore(newStore);
212}
213
214ProgramStateRef ProgramState::killBinding(Loc LV) const {
215  assert(!LV.getAs<loc::MemRegionVal>() && "Use invalidateRegion instead.");
216
217  Store OldStore = getStore();
218  const StoreRef &newStore =
219    getStateManager().StoreMgr->killBinding(OldStore, LV);
220
221  if (newStore.getStore() == OldStore)
222    return this;
223
224  return makeWithStore(newStore);
225}
226
227ProgramStateRef
228ProgramState::enterStackFrame(const CallEvent &Call,
229                              const StackFrameContext *CalleeCtx) const {
230  const StoreRef &NewStore =
231    getStateManager().StoreMgr->enterStackFrame(getStore(), Call, CalleeCtx);
232  return makeWithStore(NewStore);
233}
234
235SVal ProgramState::getSValAsScalarOrLoc(const MemRegion *R) const {
236  // We only want to do fetches from regions that we can actually bind
237  // values.  For example, SymbolicRegions of type 'id<...>' cannot
238  // have direct bindings (but their can be bindings on their subregions).
239  if (!R->isBoundable())
240    return UnknownVal();
241
242  if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
243    QualType T = TR->getValueType();
244    if (Loc::isLocType(T) || T->isIntegralOrEnumerationType())
245      return getSVal(R);
246  }
247
248  return UnknownVal();
249}
250
251SVal ProgramState::getSVal(Loc location, QualType T) const {
252  SVal V = getRawSVal(cast<Loc>(location), T);
253
254  // If 'V' is a symbolic value that is *perfectly* constrained to
255  // be a constant value, use that value instead to lessen the burden
256  // on later analysis stages (so we have less symbolic values to reason
257  // about).
258  if (!T.isNull()) {
259    if (SymbolRef sym = V.getAsSymbol()) {
260      if (const llvm::APSInt *Int = getStateManager()
261                                    .getConstraintManager()
262                                    .getSymVal(this, sym)) {
263        // FIXME: Because we don't correctly model (yet) sign-extension
264        // and truncation of symbolic values, we need to convert
265        // the integer value to the correct signedness and bitwidth.
266        //
267        // This shows up in the following:
268        //
269        //   char foo();
270        //   unsigned x = foo();
271        //   if (x == 54)
272        //     ...
273        //
274        //  The symbolic value stored to 'x' is actually the conjured
275        //  symbol for the call to foo(); the type of that symbol is 'char',
276        //  not unsigned.
277        const llvm::APSInt &NewV = getBasicVals().Convert(T, *Int);
278
279        if (V.getAs<Loc>())
280          return loc::ConcreteInt(NewV);
281        else
282          return nonloc::ConcreteInt(NewV);
283      }
284    }
285  }
286
287  return V;
288}
289
290ProgramStateRef ProgramState::BindExpr(const Stmt *S,
291                                           const LocationContext *LCtx,
292                                           SVal V, bool Invalidate) const{
293  Environment NewEnv =
294    getStateManager().EnvMgr.bindExpr(Env, EnvironmentEntry(S, LCtx), V,
295                                      Invalidate);
296  if (NewEnv == Env)
297    return this;
298
299  ProgramState NewSt = *this;
300  NewSt.Env = NewEnv;
301  return getStateManager().getPersistentState(NewSt);
302}
303
304ProgramStateRef ProgramState::assumeInBound(DefinedOrUnknownSVal Idx,
305                                      DefinedOrUnknownSVal UpperBound,
306                                      bool Assumption,
307                                      QualType indexTy) const {
308  if (Idx.isUnknown() || UpperBound.isUnknown())
309    return this;
310
311  // Build an expression for 0 <= Idx < UpperBound.
312  // This is the same as Idx + MIN < UpperBound + MIN, if overflow is allowed.
313  // FIXME: This should probably be part of SValBuilder.
314  ProgramStateManager &SM = getStateManager();
315  SValBuilder &svalBuilder = SM.getSValBuilder();
316  ASTContext &Ctx = svalBuilder.getContext();
317
318  // Get the offset: the minimum value of the array index type.
319  BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
320  // FIXME: This should be using ValueManager::ArrayindexTy...somehow.
321  if (indexTy.isNull())
322    indexTy = Ctx.IntTy;
323  nonloc::ConcreteInt Min(BVF.getMinValue(indexTy));
324
325  // Adjust the index.
326  SVal newIdx = svalBuilder.evalBinOpNN(this, BO_Add,
327                                        Idx.castAs<NonLoc>(), Min, indexTy);
328  if (newIdx.isUnknownOrUndef())
329    return this;
330
331  // Adjust the upper bound.
332  SVal newBound =
333    svalBuilder.evalBinOpNN(this, BO_Add, UpperBound.castAs<NonLoc>(),
334                            Min, indexTy);
335
336  if (newBound.isUnknownOrUndef())
337    return this;
338
339  // Build the actual comparison.
340  SVal inBound = svalBuilder.evalBinOpNN(this, BO_LT, newIdx.castAs<NonLoc>(),
341                                         newBound.castAs<NonLoc>(), Ctx.IntTy);
342  if (inBound.isUnknownOrUndef())
343    return this;
344
345  // Finally, let the constraint manager take care of it.
346  ConstraintManager &CM = SM.getConstraintManager();
347  return CM.assume(this, inBound.castAs<DefinedSVal>(), Assumption);
348}
349
350ConditionTruthVal ProgramState::isNull(SVal V) const {
351  if (V.isZeroConstant())
352    return true;
353
354  if (V.isConstant())
355    return false;
356
357  SymbolRef Sym = V.getAsSymbol(/* IncludeBaseRegion */ true);
358  if (!Sym)
359    return ConditionTruthVal();
360
361  return getStateManager().ConstraintMgr->isNull(this, Sym);
362}
363
364ProgramStateRef ProgramStateManager::getInitialState(const LocationContext *InitLoc) {
365  ProgramState State(this,
366                EnvMgr.getInitialEnvironment(),
367                StoreMgr->getInitialStore(InitLoc),
368                GDMFactory.getEmptyMap());
369
370  return getPersistentState(State);
371}
372
373ProgramStateRef ProgramStateManager::getPersistentStateWithGDM(
374                                                     ProgramStateRef FromState,
375                                                     ProgramStateRef GDMState) {
376  ProgramState NewState(*FromState);
377  NewState.GDM = GDMState->GDM;
378  return getPersistentState(NewState);
379}
380
381ProgramStateRef ProgramStateManager::getPersistentState(ProgramState &State) {
382
383  llvm::FoldingSetNodeID ID;
384  State.Profile(ID);
385  void *InsertPos;
386
387  if (ProgramState *I = StateSet.FindNodeOrInsertPos(ID, InsertPos))
388    return I;
389
390  ProgramState *newState = nullptr;
391  if (!freeStates.empty()) {
392    newState = freeStates.back();
393    freeStates.pop_back();
394  }
395  else {
396    newState = (ProgramState*) Alloc.Allocate<ProgramState>();
397  }
398  new (newState) ProgramState(State);
399  StateSet.InsertNode(newState, InsertPos);
400  return newState;
401}
402
403ProgramStateRef ProgramState::makeWithStore(const StoreRef &store) const {
404  ProgramState NewSt(*this);
405  NewSt.setStore(store);
406  return getStateManager().getPersistentState(NewSt);
407}
408
409void ProgramState::setStore(const StoreRef &newStore) {
410  Store newStoreStore = newStore.getStore();
411  if (newStoreStore)
412    stateMgr->getStoreManager().incrementReferenceCount(newStoreStore);
413  if (store)
414    stateMgr->getStoreManager().decrementReferenceCount(store);
415  store = newStoreStore;
416}
417
418//===----------------------------------------------------------------------===//
419//  State pretty-printing.
420//===----------------------------------------------------------------------===//
421
422void ProgramState::print(raw_ostream &Out,
423                         const char *NL, const char *Sep) const {
424  // Print the store.
425  ProgramStateManager &Mgr = getStateManager();
426  Mgr.getStoreManager().print(getStore(), Out, NL, Sep);
427
428  // Print out the environment.
429  Env.print(Out, NL, Sep);
430
431  // Print out the constraints.
432  Mgr.getConstraintManager().print(this, Out, NL, Sep);
433
434  // Print checker-specific data.
435  Mgr.getOwningEngine()->printState(Out, this, NL, Sep);
436}
437
438void ProgramState::printDOT(raw_ostream &Out) const {
439  print(Out, "\\l", "\\|");
440}
441
442void ProgramState::dump() const {
443  print(llvm::errs());
444}
445
446void ProgramState::printTaint(raw_ostream &Out,
447                              const char *NL, const char *Sep) const {
448  TaintMapImpl TM = get<TaintMap>();
449
450  if (!TM.isEmpty())
451    Out <<"Tainted Symbols:" << NL;
452
453  for (TaintMapImpl::iterator I = TM.begin(), E = TM.end(); I != E; ++I) {
454    Out << I->first << " : " << I->second << NL;
455  }
456}
457
458void ProgramState::dumpTaint() const {
459  printTaint(llvm::errs());
460}
461
462//===----------------------------------------------------------------------===//
463// Generic Data Map.
464//===----------------------------------------------------------------------===//
465
466void *const* ProgramState::FindGDM(void *K) const {
467  return GDM.lookup(K);
468}
469
470void*
471ProgramStateManager::FindGDMContext(void *K,
472                               void *(*CreateContext)(llvm::BumpPtrAllocator&),
473                               void (*DeleteContext)(void*)) {
474
475  std::pair<void*, void (*)(void*)>& p = GDMContexts[K];
476  if (!p.first) {
477    p.first = CreateContext(Alloc);
478    p.second = DeleteContext;
479  }
480
481  return p.first;
482}
483
484ProgramStateRef ProgramStateManager::addGDM(ProgramStateRef St, void *Key, void *Data){
485  ProgramState::GenericDataMap M1 = St->getGDM();
486  ProgramState::GenericDataMap M2 = GDMFactory.add(M1, Key, Data);
487
488  if (M1 == M2)
489    return St;
490
491  ProgramState NewSt = *St;
492  NewSt.GDM = M2;
493  return getPersistentState(NewSt);
494}
495
496ProgramStateRef ProgramStateManager::removeGDM(ProgramStateRef state, void *Key) {
497  ProgramState::GenericDataMap OldM = state->getGDM();
498  ProgramState::GenericDataMap NewM = GDMFactory.remove(OldM, Key);
499
500  if (NewM == OldM)
501    return state;
502
503  ProgramState NewState = *state;
504  NewState.GDM = NewM;
505  return getPersistentState(NewState);
506}
507
508bool ScanReachableSymbols::scan(nonloc::LazyCompoundVal val) {
509  bool wasVisited = !visited.insert(val.getCVData()).second;
510  if (wasVisited)
511    return true;
512
513  StoreManager &StoreMgr = state->getStateManager().getStoreManager();
514  // FIXME: We don't really want to use getBaseRegion() here because pointer
515  // arithmetic doesn't apply, but scanReachableSymbols only accepts base
516  // regions right now.
517  const MemRegion *R = val.getRegion()->getBaseRegion();
518  return StoreMgr.scanReachableSymbols(val.getStore(), R, *this);
519}
520
521bool ScanReachableSymbols::scan(nonloc::CompoundVal val) {
522  for (nonloc::CompoundVal::iterator I=val.begin(), E=val.end(); I!=E; ++I)
523    if (!scan(*I))
524      return false;
525
526  return true;
527}
528
529bool ScanReachableSymbols::scan(const SymExpr *sym) {
530  bool wasVisited = !visited.insert(sym).second;
531  if (wasVisited)
532    return true;
533
534  if (!visitor.VisitSymbol(sym))
535    return false;
536
537  // TODO: should be rewritten using SymExpr::symbol_iterator.
538  switch (sym->getKind()) {
539    case SymExpr::RegionValueKind:
540    case SymExpr::ConjuredKind:
541    case SymExpr::DerivedKind:
542    case SymExpr::ExtentKind:
543    case SymExpr::MetadataKind:
544      break;
545    case SymExpr::CastSymbolKind:
546      return scan(cast<SymbolCast>(sym)->getOperand());
547    case SymExpr::SymIntKind:
548      return scan(cast<SymIntExpr>(sym)->getLHS());
549    case SymExpr::IntSymKind:
550      return scan(cast<IntSymExpr>(sym)->getRHS());
551    case SymExpr::SymSymKind: {
552      const SymSymExpr *x = cast<SymSymExpr>(sym);
553      return scan(x->getLHS()) && scan(x->getRHS());
554    }
555  }
556  return true;
557}
558
559bool ScanReachableSymbols::scan(SVal val) {
560  if (Optional<loc::MemRegionVal> X = val.getAs<loc::MemRegionVal>())
561    return scan(X->getRegion());
562
563  if (Optional<nonloc::LazyCompoundVal> X =
564          val.getAs<nonloc::LazyCompoundVal>())
565    return scan(*X);
566
567  if (Optional<nonloc::LocAsInteger> X = val.getAs<nonloc::LocAsInteger>())
568    return scan(X->getLoc());
569
570  if (SymbolRef Sym = val.getAsSymbol())
571    return scan(Sym);
572
573  if (const SymExpr *Sym = val.getAsSymbolicExpression())
574    return scan(Sym);
575
576  if (Optional<nonloc::CompoundVal> X = val.getAs<nonloc::CompoundVal>())
577    return scan(*X);
578
579  return true;
580}
581
582bool ScanReachableSymbols::scan(const MemRegion *R) {
583  if (isa<MemSpaceRegion>(R))
584    return true;
585
586  bool wasVisited = !visited.insert(R).second;
587  if (wasVisited)
588    return true;
589
590  if (!visitor.VisitMemRegion(R))
591    return false;
592
593  // If this is a symbolic region, visit the symbol for the region.
594  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
595    if (!visitor.VisitSymbol(SR->getSymbol()))
596      return false;
597
598  // If this is a subregion, also visit the parent regions.
599  if (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
600    const MemRegion *Super = SR->getSuperRegion();
601    if (!scan(Super))
602      return false;
603
604    // When we reach the topmost region, scan all symbols in it.
605    if (isa<MemSpaceRegion>(Super)) {
606      StoreManager &StoreMgr = state->getStateManager().getStoreManager();
607      if (!StoreMgr.scanReachableSymbols(state->getStore(), SR, *this))
608        return false;
609    }
610  }
611
612  // Regions captured by a block are also implicitly reachable.
613  if (const BlockDataRegion *BDR = dyn_cast<BlockDataRegion>(R)) {
614    BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(),
615                                              E = BDR->referenced_vars_end();
616    for ( ; I != E; ++I) {
617      if (!scan(I.getCapturedRegion()))
618        return false;
619    }
620  }
621
622  return true;
623}
624
625bool ProgramState::scanReachableSymbols(SVal val, SymbolVisitor& visitor) const {
626  ScanReachableSymbols S(this, visitor);
627  return S.scan(val);
628}
629
630bool ProgramState::scanReachableSymbols(const SVal *I, const SVal *E,
631                                   SymbolVisitor &visitor) const {
632  ScanReachableSymbols S(this, visitor);
633  for ( ; I != E; ++I) {
634    if (!S.scan(*I))
635      return false;
636  }
637  return true;
638}
639
640bool ProgramState::scanReachableSymbols(const MemRegion * const *I,
641                                   const MemRegion * const *E,
642                                   SymbolVisitor &visitor) const {
643  ScanReachableSymbols S(this, visitor);
644  for ( ; I != E; ++I) {
645    if (!S.scan(*I))
646      return false;
647  }
648  return true;
649}
650
651ProgramStateRef ProgramState::addTaint(const Stmt *S,
652                                           const LocationContext *LCtx,
653                                           TaintTagType Kind) const {
654  if (const Expr *E = dyn_cast_or_null<Expr>(S))
655    S = E->IgnoreParens();
656
657  SymbolRef Sym = getSVal(S, LCtx).getAsSymbol();
658  if (Sym)
659    return addTaint(Sym, Kind);
660
661  const MemRegion *R = getSVal(S, LCtx).getAsRegion();
662  addTaint(R, Kind);
663
664  // Cannot add taint, so just return the state.
665  return this;
666}
667
668ProgramStateRef ProgramState::addTaint(const MemRegion *R,
669                                           TaintTagType Kind) const {
670  if (const SymbolicRegion *SR = dyn_cast_or_null<SymbolicRegion>(R))
671    return addTaint(SR->getSymbol(), Kind);
672  return this;
673}
674
675ProgramStateRef ProgramState::addTaint(SymbolRef Sym,
676                                           TaintTagType Kind) const {
677  // If this is a symbol cast, remove the cast before adding the taint. Taint
678  // is cast agnostic.
679  while (const SymbolCast *SC = dyn_cast<SymbolCast>(Sym))
680    Sym = SC->getOperand();
681
682  ProgramStateRef NewState = set<TaintMap>(Sym, Kind);
683  assert(NewState);
684  return NewState;
685}
686
687bool ProgramState::isTainted(const Stmt *S, const LocationContext *LCtx,
688                             TaintTagType Kind) const {
689  if (const Expr *E = dyn_cast_or_null<Expr>(S))
690    S = E->IgnoreParens();
691
692  SVal val = getSVal(S, LCtx);
693  return isTainted(val, Kind);
694}
695
696bool ProgramState::isTainted(SVal V, TaintTagType Kind) const {
697  if (const SymExpr *Sym = V.getAsSymExpr())
698    return isTainted(Sym, Kind);
699  if (const MemRegion *Reg = V.getAsRegion())
700    return isTainted(Reg, Kind);
701  return false;
702}
703
704bool ProgramState::isTainted(const MemRegion *Reg, TaintTagType K) const {
705  if (!Reg)
706    return false;
707
708  // Element region (array element) is tainted if either the base or the offset
709  // are tainted.
710  if (const ElementRegion *ER = dyn_cast<ElementRegion>(Reg))
711    return isTainted(ER->getSuperRegion(), K) || isTainted(ER->getIndex(), K);
712
713  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(Reg))
714    return isTainted(SR->getSymbol(), K);
715
716  if (const SubRegion *ER = dyn_cast<SubRegion>(Reg))
717    return isTainted(ER->getSuperRegion(), K);
718
719  return false;
720}
721
722bool ProgramState::isTainted(SymbolRef Sym, TaintTagType Kind) const {
723  if (!Sym)
724    return false;
725
726  // Traverse all the symbols this symbol depends on to see if any are tainted.
727  bool Tainted = false;
728  for (SymExpr::symbol_iterator SI = Sym->symbol_begin(), SE =Sym->symbol_end();
729       SI != SE; ++SI) {
730    if (!isa<SymbolData>(*SI))
731      continue;
732
733    const TaintTagType *Tag = get<TaintMap>(*SI);
734    Tainted = (Tag && *Tag == Kind);
735
736    // If this is a SymbolDerived with a tainted parent, it's also tainted.
737    if (const SymbolDerived *SD = dyn_cast<SymbolDerived>(*SI))
738      Tainted = Tainted || isTainted(SD->getParentSymbol(), Kind);
739
740    // If memory region is tainted, data is also tainted.
741    if (const SymbolRegionValue *SRV = dyn_cast<SymbolRegionValue>(*SI))
742      Tainted = Tainted || isTainted(SRV->getRegion(), Kind);
743
744    // If If this is a SymbolCast from a tainted value, it's also tainted.
745    if (const SymbolCast *SC = dyn_cast<SymbolCast>(*SI))
746      Tainted = Tainted || isTainted(SC->getOperand(), Kind);
747
748    if (Tainted)
749      return true;
750  }
751
752  return Tainted;
753}
754
755/// The GDM component containing the dynamic type info. This is a map from a
756/// symbol to its most likely type.
757REGISTER_TRAIT_WITH_PROGRAMSTATE(DynamicTypeMap,
758                                 CLANG_ENTO_PROGRAMSTATE_MAP(const MemRegion *,
759                                                             DynamicTypeInfo))
760
761DynamicTypeInfo ProgramState::getDynamicTypeInfo(const MemRegion *Reg) const {
762  Reg = Reg->StripCasts();
763
764  // Look up the dynamic type in the GDM.
765  const DynamicTypeInfo *GDMType = get<DynamicTypeMap>(Reg);
766  if (GDMType)
767    return *GDMType;
768
769  // Otherwise, fall back to what we know about the region.
770  if (const TypedRegion *TR = dyn_cast<TypedRegion>(Reg))
771    return DynamicTypeInfo(TR->getLocationType(), /*CanBeSubclass=*/false);
772
773  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(Reg)) {
774    SymbolRef Sym = SR->getSymbol();
775    return DynamicTypeInfo(Sym->getType());
776  }
777
778  return DynamicTypeInfo();
779}
780
781ProgramStateRef ProgramState::setDynamicTypeInfo(const MemRegion *Reg,
782                                                 DynamicTypeInfo NewTy) const {
783  Reg = Reg->StripCasts();
784  ProgramStateRef NewState = set<DynamicTypeMap>(Reg, NewTy);
785  assert(NewState);
786  return NewState;
787}
788