ProgramState.cpp revision aace9ef279be3dadd53b481aee568bd7701178b4 
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/Analysis/CFG.h"
15#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
16#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/SubEngine.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/TaintManager.h"
19#include "llvm/Support/raw_ostream.h"
20
21using namespace clang;
22using namespace ento;
23
24// Give the vtable for ConstraintManager somewhere to live.
25// FIXME: Move this elsewhere.
26ConstraintManager::~ConstraintManager() {}
27
28ProgramState::ProgramState(ProgramStateManager *mgr, const Environment& env,
29                 StoreRef st, GenericDataMap gdm)
30  : stateMgr(mgr),
31    Env(env),
32    store(st.getStore()),
33    GDM(gdm),
34    refCount(0) {
35  stateMgr->getStoreManager().incrementReferenceCount(store);
36}
37
38ProgramState::ProgramState(const ProgramState &RHS)
39    : llvm::FoldingSetNode(),
40      stateMgr(RHS.stateMgr),
41      Env(RHS.Env),
42      store(RHS.store),
43      GDM(RHS.GDM),
44      refCount(0) {
45  stateMgr->getStoreManager().incrementReferenceCount(store);
46}
47
48ProgramState::~ProgramState() {
49  if (store)
50    stateMgr->getStoreManager().decrementReferenceCount(store);
51}
52
53ProgramStateManager::~ProgramStateManager() {
54  for (GDMContextsTy::iterator I=GDMContexts.begin(), E=GDMContexts.end();
55       I!=E; ++I)
56    I->second.second(I->second.first);
57}
58
59const ProgramState*
60ProgramStateManager::removeDeadBindings(const ProgramState *state,
61                                   const StackFrameContext *LCtx,
62                                   SymbolReaper& SymReaper) {
63
64  // This code essentially performs a "mark-and-sweep" of the VariableBindings.
65  // The roots are any Block-level exprs and Decls that our liveness algorithm
66  // tells us are live.  We then see what Decls they may reference, and keep
67  // those around.  This code more than likely can be made faster, and the
68  // frequency of which this method is called should be experimented with
69  // for optimum performance.
70  ProgramState NewState = *state;
71
72  NewState.Env = EnvMgr.removeDeadBindings(NewState.Env, SymReaper, state);
73
74  // Clean up the store.
75  StoreRef newStore = StoreMgr->removeDeadBindings(NewState.getStore(), LCtx,
76                                                   SymReaper);
77  NewState.setStore(newStore);
78  SymReaper.setReapedStore(newStore);
79
80  return getPersistentState(NewState);
81}
82
83const ProgramState *ProgramStateManager::MarshalState(const ProgramState *state,
84                                            const StackFrameContext *InitLoc) {
85  // make up an empty state for now.
86  ProgramState State(this,
87                EnvMgr.getInitialEnvironment(),
88                StoreMgr->getInitialStore(InitLoc),
89                GDMFactory.getEmptyMap());
90
91  return getPersistentState(State);
92}
93
94const ProgramState *ProgramState::bindCompoundLiteral(const CompoundLiteralExpr *CL,
95                                            const LocationContext *LC,
96                                            SVal V) const {
97  const StoreRef &newStore =
98    getStateManager().StoreMgr->BindCompoundLiteral(getStore(), CL, LC, V);
99  return makeWithStore(newStore);
100}
101
102const ProgramState *ProgramState::bindDecl(const VarRegion* VR, SVal IVal) const {
103  const StoreRef &newStore =
104    getStateManager().StoreMgr->BindDecl(getStore(), VR, IVal);
105  return makeWithStore(newStore);
106}
107
108const ProgramState *ProgramState::bindDeclWithNoInit(const VarRegion* VR) const {
109  const StoreRef &newStore =
110    getStateManager().StoreMgr->BindDeclWithNoInit(getStore(), VR);
111  return makeWithStore(newStore);
112}
113
114const ProgramState *ProgramState::bindLoc(Loc LV, SVal V) const {
115  ProgramStateManager &Mgr = getStateManager();
116  const ProgramState *newState = makeWithStore(Mgr.StoreMgr->Bind(getStore(),
117                                                             LV, V));
118  const MemRegion *MR = LV.getAsRegion();
119  if (MR && Mgr.getOwningEngine())
120    return Mgr.getOwningEngine()->processRegionChange(newState, MR);
121
122  return newState;
123}
124
125const ProgramState *ProgramState::bindDefault(SVal loc, SVal V) const {
126  ProgramStateManager &Mgr = getStateManager();
127  const MemRegion *R = cast<loc::MemRegionVal>(loc).getRegion();
128  const StoreRef &newStore = Mgr.StoreMgr->BindDefault(getStore(), R, V);
129  const ProgramState *new_state = makeWithStore(newStore);
130  return Mgr.getOwningEngine() ?
131           Mgr.getOwningEngine()->processRegionChange(new_state, R) :
132           new_state;
133}
134
135const ProgramState *
136ProgramState::invalidateRegions(ArrayRef<const MemRegion *> Regions,
137                                const Expr *E, unsigned Count,
138                                StoreManager::InvalidatedSymbols *IS,
139                                bool invalidateGlobals) const {
140  if (!IS) {
141    StoreManager::InvalidatedSymbols invalidated;
142    return invalidateRegionsImpl(Regions, E, Count,
143                                 invalidated, invalidateGlobals);
144  }
145  return invalidateRegionsImpl(Regions, E, Count, *IS, invalidateGlobals);
146}
147
148const ProgramState *
149ProgramState::invalidateRegionsImpl(ArrayRef<const MemRegion *> Regions,
150                                    const Expr *E, unsigned Count,
151                                    StoreManager::InvalidatedSymbols &IS,
152                                    bool invalidateGlobals) const {
153  ProgramStateManager &Mgr = getStateManager();
154  SubEngine* Eng = Mgr.getOwningEngine();
155
156  if (Eng && Eng->wantsRegionChangeUpdate(this)) {
157    StoreManager::InvalidatedRegions Invalidated;
158    const StoreRef &newStore
159      = Mgr.StoreMgr->invalidateRegions(getStore(), Regions, E, Count, IS,
160                                        invalidateGlobals, &Invalidated);
161    const ProgramState *newState = makeWithStore(newStore);
162    return Eng->processRegionChanges(newState, &IS, Regions, Invalidated);
163  }
164
165  const StoreRef &newStore =
166    Mgr.StoreMgr->invalidateRegions(getStore(), Regions, E, Count, IS,
167                                    invalidateGlobals, NULL);
168  return makeWithStore(newStore);
169}
170
171const ProgramState *ProgramState::unbindLoc(Loc LV) const {
172  assert(!isa<loc::MemRegionVal>(LV) && "Use invalidateRegion instead.");
173
174  Store OldStore = getStore();
175  const StoreRef &newStore = getStateManager().StoreMgr->Remove(OldStore, LV);
176
177  if (newStore.getStore() == OldStore)
178    return this;
179
180  return makeWithStore(newStore);
181}
182
183const ProgramState *ProgramState::enterStackFrame(const StackFrameContext *frame) const {
184  const StoreRef &new_store =
185    getStateManager().StoreMgr->enterStackFrame(this, frame);
186  return makeWithStore(new_store);
187}
188
189SVal ProgramState::getSValAsScalarOrLoc(const MemRegion *R) const {
190  // We only want to do fetches from regions that we can actually bind
191  // values.  For example, SymbolicRegions of type 'id<...>' cannot
192  // have direct bindings (but their can be bindings on their subregions).
193  if (!R->isBoundable())
194    return UnknownVal();
195
196  if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
197    QualType T = TR->getValueType();
198    if (Loc::isLocType(T) || T->isIntegerType())
199      return getSVal(R);
200  }
201
202  return UnknownVal();
203}
204
205SVal ProgramState::getSVal(Loc location, QualType T) const {
206  SVal V = getRawSVal(cast<Loc>(location), T);
207
208  // If 'V' is a symbolic value that is *perfectly* constrained to
209  // be a constant value, use that value instead to lessen the burden
210  // on later analysis stages (so we have less symbolic values to reason
211  // about).
212  if (!T.isNull()) {
213    if (SymbolRef sym = V.getAsSymbol()) {
214      if (const llvm::APSInt *Int = getSymVal(sym)) {
215        // FIXME: Because we don't correctly model (yet) sign-extension
216        // and truncation of symbolic values, we need to convert
217        // the integer value to the correct signedness and bitwidth.
218        //
219        // This shows up in the following:
220        //
221        //   char foo();
222        //   unsigned x = foo();
223        //   if (x == 54)
224        //     ...
225        //
226        //  The symbolic value stored to 'x' is actually the conjured
227        //  symbol for the call to foo(); the type of that symbol is 'char',
228        //  not unsigned.
229        const llvm::APSInt &NewV = getBasicVals().Convert(T, *Int);
230
231        if (isa<Loc>(V))
232          return loc::ConcreteInt(NewV);
233        else
234          return nonloc::ConcreteInt(NewV);
235      }
236    }
237  }
238
239  return V;
240}
241
242const ProgramState *ProgramState::BindExpr(const Stmt *S, SVal V, bool Invalidate) const{
243  Environment NewEnv = getStateManager().EnvMgr.bindExpr(Env, S, V,
244                                                         Invalidate);
245  if (NewEnv == Env)
246    return this;
247
248  ProgramState NewSt = *this;
249  NewSt.Env = NewEnv;
250  return getStateManager().getPersistentState(NewSt);
251}
252
253const ProgramState *ProgramState::bindExprAndLocation(const Stmt *S, SVal location,
254                                            SVal V) const {
255  Environment NewEnv =
256    getStateManager().EnvMgr.bindExprAndLocation(Env, S, location, V);
257
258  if (NewEnv == Env)
259    return this;
260
261  ProgramState NewSt = *this;
262  NewSt.Env = NewEnv;
263  return getStateManager().getPersistentState(NewSt);
264}
265
266const ProgramState *ProgramState::assumeInBound(DefinedOrUnknownSVal Idx,
267                                      DefinedOrUnknownSVal UpperBound,
268                                      bool Assumption) const {
269  if (Idx.isUnknown() || UpperBound.isUnknown())
270    return this;
271
272  // Build an expression for 0 <= Idx < UpperBound.
273  // This is the same as Idx + MIN < UpperBound + MIN, if overflow is allowed.
274  // FIXME: This should probably be part of SValBuilder.
275  ProgramStateManager &SM = getStateManager();
276  SValBuilder &svalBuilder = SM.getSValBuilder();
277  ASTContext &Ctx = svalBuilder.getContext();
278
279  // Get the offset: the minimum value of the array index type.
280  BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
281  // FIXME: This should be using ValueManager::ArrayindexTy...somehow.
282  QualType indexTy = Ctx.IntTy;
283  nonloc::ConcreteInt Min(BVF.getMinValue(indexTy));
284
285  // Adjust the index.
286  SVal newIdx = svalBuilder.evalBinOpNN(this, BO_Add,
287                                        cast<NonLoc>(Idx), Min, indexTy);
288  if (newIdx.isUnknownOrUndef())
289    return this;
290
291  // Adjust the upper bound.
292  SVal newBound =
293    svalBuilder.evalBinOpNN(this, BO_Add, cast<NonLoc>(UpperBound),
294                            Min, indexTy);
295
296  if (newBound.isUnknownOrUndef())
297    return this;
298
299  // Build the actual comparison.
300  SVal inBound = svalBuilder.evalBinOpNN(this, BO_LT,
301                                cast<NonLoc>(newIdx), cast<NonLoc>(newBound),
302                                Ctx.IntTy);
303  if (inBound.isUnknownOrUndef())
304    return this;
305
306  // Finally, let the constraint manager take care of it.
307  ConstraintManager &CM = SM.getConstraintManager();
308  return CM.assume(this, cast<DefinedSVal>(inBound), Assumption);
309}
310
311const ProgramState *ProgramStateManager::getInitialState(const LocationContext *InitLoc) {
312  ProgramState State(this,
313                EnvMgr.getInitialEnvironment(),
314                StoreMgr->getInitialStore(InitLoc),
315                GDMFactory.getEmptyMap());
316
317  return getPersistentState(State);
318}
319
320void ProgramStateManager::recycleUnusedStates() {
321  for (std::vector<ProgramState*>::iterator i = recentlyAllocatedStates.begin(),
322       e = recentlyAllocatedStates.end(); i != e; ++i) {
323    ProgramState *state = *i;
324    if (state->referencedByExplodedNode())
325      continue;
326    StateSet.RemoveNode(state);
327    freeStates.push_back(state);
328    state->~ProgramState();
329  }
330  recentlyAllocatedStates.clear();
331}
332
333const ProgramState *ProgramStateManager::getPersistentStateWithGDM(
334                                                     const ProgramState *FromState,
335                                                     const ProgramState *GDMState) {
336  ProgramState NewState = *FromState;
337  NewState.GDM = GDMState->GDM;
338  return getPersistentState(NewState);
339}
340
341const ProgramState *ProgramStateManager::getPersistentState(ProgramState &State) {
342
343  llvm::FoldingSetNodeID ID;
344  State.Profile(ID);
345  void *InsertPos;
346
347  if (ProgramState *I = StateSet.FindNodeOrInsertPos(ID, InsertPos))
348    return I;
349
350  ProgramState *newState = 0;
351  if (!freeStates.empty()) {
352    newState = freeStates.back();
353    freeStates.pop_back();
354  }
355  else {
356    newState = (ProgramState*) Alloc.Allocate<ProgramState>();
357  }
358  new (newState) ProgramState(State);
359  StateSet.InsertNode(newState, InsertPos);
360  recentlyAllocatedStates.push_back(newState);
361  return newState;
362}
363
364const ProgramState *ProgramState::makeWithStore(const StoreRef &store) const {
365  ProgramState NewSt = *this;
366  NewSt.setStore(store);
367  return getStateManager().getPersistentState(NewSt);
368}
369
370void ProgramState::setStore(const StoreRef &newStore) {
371  Store newStoreStore = newStore.getStore();
372  if (newStoreStore)
373    stateMgr->getStoreManager().incrementReferenceCount(newStoreStore);
374  if (store)
375    stateMgr->getStoreManager().decrementReferenceCount(store);
376  store = newStoreStore;
377}
378
379//===----------------------------------------------------------------------===//
380//  State pretty-printing.
381//===----------------------------------------------------------------------===//
382
383static bool IsEnvLoc(const Stmt *S) {
384  // FIXME: This is a layering violation.  Should be in environment.
385  return (bool) (((uintptr_t) S) & 0x1);
386}
387
388void ProgramState::print(raw_ostream &Out, CFG *C,
389                         const char *NL, const char *Sep) const {
390  // Print the store.
391  ProgramStateManager &Mgr = getStateManager();
392  Mgr.getStoreManager().print(getStore(), Out, NL, Sep);
393  bool isFirst = true;
394
395  // FIXME: All environment printing should be moved inside Environment.
396  if (C) {
397    // Print Subexpression bindings.
398    for (Environment::iterator I = Env.begin(), E = Env.end(); I != E; ++I) {
399      if (C->isBlkExpr(I.getKey()) || IsEnvLoc(I.getKey()))
400        continue;
401
402      if (isFirst) {
403        Out << NL << NL << "Sub-Expressions:" << NL;
404        isFirst = false;
405      } else {
406        Out << NL;
407      }
408
409      Out << " (" << (void*) I.getKey() << ") ";
410      LangOptions LO; // FIXME.
411      I.getKey()->printPretty(Out, 0, PrintingPolicy(LO));
412      Out << " : " << I.getData();
413    }
414
415    // Print block-expression bindings.
416    isFirst = true;
417    for (Environment::iterator I = Env.begin(), E = Env.end(); I != E; ++I) {
418      if (!C->isBlkExpr(I.getKey()))
419        continue;
420
421      if (isFirst) {
422        Out << NL << NL << "Block-level Expressions:" << NL;
423        isFirst = false;
424      } else {
425        Out << NL;
426      }
427
428      Out << " (" << (void*) I.getKey() << ") ";
429      LangOptions LO; // FIXME.
430      I.getKey()->printPretty(Out, 0, PrintingPolicy(LO));
431      Out << " : " << I.getData();
432    }
433  } else {
434    // Print All bindings - no info to differentiate block from subexpressions.
435    for (Environment::iterator I = Env.begin(), E = Env.end(); I != E; ++I) {
436      if (IsEnvLoc(I.getKey()))
437        continue;
438
439      if (isFirst) {
440        Out << NL << NL << "Expressions:" << NL;
441        isFirst = false;
442      } else {
443        Out << NL;
444      }
445
446      Out << " (" << (void*) I.getKey() << ") ";
447      LangOptions LO; // FIXME.
448      I.getKey()->printPretty(Out, 0, PrintingPolicy(LO));
449      Out << " : " << I.getData();
450    }
451  }
452
453  // Print locations.
454  isFirst = true;
455
456  for (Environment::iterator I = Env.begin(), E = Env.end(); I != E; ++I) {
457    if (!IsEnvLoc(I.getKey()))
458      continue;
459
460    if (isFirst) {
461      Out << NL << NL << "Load/store locations:" << NL;
462      isFirst = false;
463    } else {
464      Out << NL;
465    }
466
467    const Stmt *S = (Stmt*) (((uintptr_t) I.getKey()) & ((uintptr_t) ~0x1));
468
469    Out << " (" << (void*) S << ") ";
470    LangOptions LO; // FIXME.
471    S->printPretty(Out, 0, PrintingPolicy(LO));
472    Out << " : " << I.getData();
473  }
474
475  Mgr.getConstraintManager().print(this, Out, NL, Sep);
476
477  // Print checker-specific data.
478  Mgr.getOwningEngine()->printState(Out, this, NL, Sep);
479}
480
481void ProgramState::printDOT(raw_ostream &Out, CFG &C) const {
482  print(Out, &C, "\\l", "\\|");
483}
484
485void ProgramState::dump(CFG &C) const {
486  print(llvm::errs(), &C);
487}
488
489void ProgramState::dump() const {
490  print(llvm::errs(), 0);
491}
492
493//===----------------------------------------------------------------------===//
494// Generic Data Map.
495//===----------------------------------------------------------------------===//
496
497void *const* ProgramState::FindGDM(void *K) const {
498  return GDM.lookup(K);
499}
500
501void*
502ProgramStateManager::FindGDMContext(void *K,
503                               void *(*CreateContext)(llvm::BumpPtrAllocator&),
504                               void (*DeleteContext)(void*)) {
505
506  std::pair<void*, void (*)(void*)>& p = GDMContexts[K];
507  if (!p.first) {
508    p.first = CreateContext(Alloc);
509    p.second = DeleteContext;
510  }
511
512  return p.first;
513}
514
515const ProgramState *ProgramStateManager::addGDM(const ProgramState *St, void *Key, void *Data){
516  ProgramState::GenericDataMap M1 = St->getGDM();
517  ProgramState::GenericDataMap M2 = GDMFactory.add(M1, Key, Data);
518
519  if (M1 == M2)
520    return St;
521
522  ProgramState NewSt = *St;
523  NewSt.GDM = M2;
524  return getPersistentState(NewSt);
525}
526
527const ProgramState *ProgramStateManager::removeGDM(const ProgramState *state, void *Key) {
528  ProgramState::GenericDataMap OldM = state->getGDM();
529  ProgramState::GenericDataMap NewM = GDMFactory.remove(OldM, Key);
530
531  if (NewM == OldM)
532    return state;
533
534  ProgramState NewState = *state;
535  NewState.GDM = NewM;
536  return getPersistentState(NewState);
537}
538
539bool ScanReachableSymbols::scan(nonloc::CompoundVal val) {
540  for (nonloc::CompoundVal::iterator I=val.begin(), E=val.end(); I!=E; ++I)
541    if (!scan(*I))
542      return false;
543
544  return true;
545}
546
547bool ScanReachableSymbols::scan(const SymExpr *sym) {
548  unsigned &isVisited = visited[sym];
549  if (isVisited)
550    return true;
551  isVisited = 1;
552
553  if (!visitor.VisitSymbol(sym))
554    return false;
555
556  switch (sym->getKind()) {
557    case SymExpr::RegionValueKind:
558    case SymExpr::ConjuredKind:
559    case SymExpr::DerivedKind:
560    case SymExpr::ExtentKind:
561    case SymExpr::MetadataKind:
562      break;
563    case SymExpr::CastSymbolKind:
564      return scan(cast<SymbolCast>(sym)->getOperand());
565    case SymExpr::SymIntKind:
566      return scan(cast<SymIntExpr>(sym)->getLHS());
567    case SymExpr::SymSymKind: {
568      const SymSymExpr *x = cast<SymSymExpr>(sym);
569      return scan(x->getLHS()) && scan(x->getRHS());
570    }
571  }
572  return true;
573}
574
575bool ScanReachableSymbols::scan(SVal val) {
576  if (loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(&val))
577    return scan(X->getRegion());
578
579  if (nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(&val))
580    return scan(X->getLoc());
581
582  if (SymbolRef Sym = val.getAsSymbol())
583    return scan(Sym);
584
585  if (const SymExpr *Sym = val.getAsSymbolicExpression())
586    return scan(Sym);
587
588  if (nonloc::CompoundVal *X = dyn_cast<nonloc::CompoundVal>(&val))
589    return scan(*X);
590
591  return true;
592}
593
594bool ScanReachableSymbols::scan(const MemRegion *R) {
595  if (isa<MemSpaceRegion>(R))
596    return true;
597
598  unsigned &isVisited = visited[R];
599  if (isVisited)
600    return true;
601  isVisited = 1;
602
603  // If this is a symbolic region, visit the symbol for the region.
604  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
605    if (!visitor.VisitSymbol(SR->getSymbol()))
606      return false;
607
608  // If this is a subregion, also visit the parent regions.
609  if (const SubRegion *SR = dyn_cast<SubRegion>(R))
610    if (!scan(SR->getSuperRegion()))
611      return false;
612
613  // Now look at the binding to this region (if any).
614  if (!scan(state->getSValAsScalarOrLoc(R)))
615    return false;
616
617  // Now look at the subregions.
618  if (!SRM.get())
619    SRM.reset(state->getStateManager().getStoreManager().
620                                           getSubRegionMap(state->getStore()));
621
622  return SRM->iterSubRegions(R, *this);
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
651const ProgramState* ProgramState::addTaint(const Stmt *S,
652                                           TaintTagType Kind) const {
653  SymbolRef Sym = getSVal(S).getAsSymbol();
654  assert(Sym && "Cannot add taint to statements whose value is not a symbol");
655  return addTaint(Sym, Kind);
656}
657
658const ProgramState* ProgramState::addTaint(SymbolRef Sym,
659                                           TaintTagType Kind) const {
660  const ProgramState *NewState = set<TaintMap>(Sym, Kind);
661  assert(NewState);
662  return NewState;
663}
664
665bool ProgramState::isTainted(const Stmt *S, TaintTagType Kind) const {
666  return isTainted(getSVal(S), Kind);
667}
668
669bool ProgramState::isTainted(SVal V, TaintTagType Kind) const {
670  return isTainted(V.getAsSymExpr(), Kind);
671}
672
673bool ProgramState::isTainted(const SymExpr* Sym, TaintTagType Kind) const {
674  if (!Sym)
675    return false;
676
677  // TODO: Can we use symbol_iterator (like removeDeadBindingsWorker) here?
678
679  // Check taint on derived symbols.
680  if (const SymbolDerived *SD = dyn_cast<SymbolDerived>(Sym))
681    return isTainted(SD->getParentSymbol(), Kind);
682
683  if (const SymbolCast *SC = dyn_cast<SymbolCast>(Sym))
684    return (isTainted(SC->getOperand(), Kind));
685
686  if (const SymIntExpr *SIE = dyn_cast<SymIntExpr>(Sym))
687    return isTainted(SIE->getLHS(), Kind);
688
689  if (const SymSymExpr *SSE = dyn_cast<SymSymExpr>(Sym))
690    return (isTainted(SSE->getLHS(), Kind) || isTainted(SSE->getRHS(), Kind));
691
692  // Check taint on the current symbol.
693  if (const SymbolData *SymR = dyn_cast<SymbolData>(Sym)) {
694    const TaintTagType *Tag = get<TaintMap>(SymR);
695    return (Tag && *Tag == Kind);
696  }
697
698  // TODO: Remove llvm unreachable.
699  llvm_unreachable("We do not know show to check taint on this symbol.");
700  return false;
701}
702