ProgramState.cpp revision 732cdf383f9030ff2b9fb28dfbdae2285ded80c6 
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/CallEvent.h"
16#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.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::bindCompoundLiteral(const CompoundLiteralExpr *CL,
115                                            const LocationContext *LC,
116                                            SVal V) const {
117  const StoreRef &newStore =
118    getStateManager().StoreMgr->bindCompoundLiteral(getStore(), CL, LC, V);
119  return makeWithStore(newStore);
120}
121
122ProgramStateRef ProgramState::bindLoc(Loc LV, SVal V, bool notifyChanges) const {
123  ProgramStateManager &Mgr = getStateManager();
124  ProgramStateRef newState = makeWithStore(Mgr.StoreMgr->Bind(getStore(),
125                                                             LV, V));
126  const MemRegion *MR = LV.getAsRegion();
127  if (MR && Mgr.getOwningEngine() && notifyChanges)
128    return Mgr.getOwningEngine()->processRegionChange(newState, MR);
129
130  return newState;
131}
132
133ProgramStateRef ProgramState::bindDefault(SVal loc, SVal V) const {
134  ProgramStateManager &Mgr = getStateManager();
135  const MemRegion *R = cast<loc::MemRegionVal>(loc).getRegion();
136  const StoreRef &newStore = Mgr.StoreMgr->BindDefault(getStore(), R, V);
137  ProgramStateRef new_state = makeWithStore(newStore);
138  return Mgr.getOwningEngine() ?
139           Mgr.getOwningEngine()->processRegionChange(new_state, R) :
140           new_state;
141}
142
143ProgramStateRef
144ProgramState::invalidateRegions(ArrayRef<const MemRegion *> Regions,
145                                const Expr *E, unsigned Count,
146                                const LocationContext *LCtx,
147                                StoreManager::InvalidatedSymbols *IS,
148                                const CallEvent *Call) const {
149  if (!IS) {
150    StoreManager::InvalidatedSymbols invalidated;
151    return invalidateRegionsImpl(Regions, E, Count, LCtx,
152                                 invalidated, Call);
153  }
154  return invalidateRegionsImpl(Regions, E, Count, LCtx, *IS, Call);
155}
156
157ProgramStateRef
158ProgramState::invalidateRegionsImpl(ArrayRef<const MemRegion *> Regions,
159                                    const Expr *E, unsigned Count,
160                                    const LocationContext *LCtx,
161                                    StoreManager::InvalidatedSymbols &IS,
162                                    const CallEvent *Call) const {
163  ProgramStateManager &Mgr = getStateManager();
164  SubEngine* Eng = Mgr.getOwningEngine();
165
166  if (Eng && Eng->wantsRegionChangeUpdate(this)) {
167    StoreManager::InvalidatedRegions Invalidated;
168    const StoreRef &newStore
169      = Mgr.StoreMgr->invalidateRegions(getStore(), Regions, E, Count, LCtx, IS,
170                                        Call, &Invalidated);
171    ProgramStateRef newState = makeWithStore(newStore);
172    return Eng->processRegionChanges(newState, &IS, Regions, Invalidated, Call);
173  }
174
175  const StoreRef &newStore =
176    Mgr.StoreMgr->invalidateRegions(getStore(), Regions, E, Count, LCtx, IS,
177                                    Call, NULL);
178  return makeWithStore(newStore);
179}
180
181ProgramStateRef ProgramState::killBinding(Loc LV) const {
182  assert(!isa<loc::MemRegionVal>(LV) && "Use invalidateRegion instead.");
183
184  Store OldStore = getStore();
185  const StoreRef &newStore =
186    getStateManager().StoreMgr->killBinding(OldStore, LV);
187
188  if (newStore.getStore() == OldStore)
189    return this;
190
191  return makeWithStore(newStore);
192}
193
194ProgramStateRef
195ProgramState::enterStackFrame(const CallEvent &Call,
196                              const StackFrameContext *CalleeCtx) const {
197  const StoreRef &NewStore =
198    getStateManager().StoreMgr->enterStackFrame(getStore(), Call, CalleeCtx);
199  return makeWithStore(NewStore);
200}
201
202SVal ProgramState::getSValAsScalarOrLoc(const MemRegion *R) const {
203  // We only want to do fetches from regions that we can actually bind
204  // values.  For example, SymbolicRegions of type 'id<...>' cannot
205  // have direct bindings (but their can be bindings on their subregions).
206  if (!R->isBoundable())
207    return UnknownVal();
208
209  if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
210    QualType T = TR->getValueType();
211    if (Loc::isLocType(T) || T->isIntegerType())
212      return getSVal(R);
213  }
214
215  return UnknownVal();
216}
217
218SVal ProgramState::getSVal(Loc location, QualType T) const {
219  SVal V = getRawSVal(cast<Loc>(location), T);
220
221  // If 'V' is a symbolic value that is *perfectly* constrained to
222  // be a constant value, use that value instead to lessen the burden
223  // on later analysis stages (so we have less symbolic values to reason
224  // about).
225  if (!T.isNull()) {
226    if (SymbolRef sym = V.getAsSymbol()) {
227      if (const llvm::APSInt *Int = getStateManager()
228                                    .getConstraintManager()
229                                    .getSymVal(this, sym)) {
230        // FIXME: Because we don't correctly model (yet) sign-extension
231        // and truncation of symbolic values, we need to convert
232        // the integer value to the correct signedness and bitwidth.
233        //
234        // This shows up in the following:
235        //
236        //   char foo();
237        //   unsigned x = foo();
238        //   if (x == 54)
239        //     ...
240        //
241        //  The symbolic value stored to 'x' is actually the conjured
242        //  symbol for the call to foo(); the type of that symbol is 'char',
243        //  not unsigned.
244        const llvm::APSInt &NewV = getBasicVals().Convert(T, *Int);
245
246        if (isa<Loc>(V))
247          return loc::ConcreteInt(NewV);
248        else
249          return nonloc::ConcreteInt(NewV);
250      }
251    }
252  }
253
254  return V;
255}
256
257ProgramStateRef ProgramState::BindExpr(const Stmt *S,
258                                           const LocationContext *LCtx,
259                                           SVal V, bool Invalidate) const{
260  Environment NewEnv =
261    getStateManager().EnvMgr.bindExpr(Env, EnvironmentEntry(S, LCtx), V,
262                                      Invalidate);
263  if (NewEnv == Env)
264    return this;
265
266  ProgramState NewSt = *this;
267  NewSt.Env = NewEnv;
268  return getStateManager().getPersistentState(NewSt);
269}
270
271ProgramStateRef
272ProgramState::bindExprAndLocation(const Stmt *S, const LocationContext *LCtx,
273                                  SVal location,
274                                  SVal V) const {
275  Environment NewEnv =
276    getStateManager().EnvMgr.bindExprAndLocation(Env,
277                                                 EnvironmentEntry(S, LCtx),
278                                                 location, V);
279
280  if (NewEnv == Env)
281    return this;
282
283  ProgramState NewSt = *this;
284  NewSt.Env = NewEnv;
285  return getStateManager().getPersistentState(NewSt);
286}
287
288ProgramStateRef ProgramState::assumeInBound(DefinedOrUnknownSVal Idx,
289                                      DefinedOrUnknownSVal UpperBound,
290                                      bool Assumption,
291                                      QualType indexTy) const {
292  if (Idx.isUnknown() || UpperBound.isUnknown())
293    return this;
294
295  // Build an expression for 0 <= Idx < UpperBound.
296  // This is the same as Idx + MIN < UpperBound + MIN, if overflow is allowed.
297  // FIXME: This should probably be part of SValBuilder.
298  ProgramStateManager &SM = getStateManager();
299  SValBuilder &svalBuilder = SM.getSValBuilder();
300  ASTContext &Ctx = svalBuilder.getContext();
301
302  // Get the offset: the minimum value of the array index type.
303  BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
304  // FIXME: This should be using ValueManager::ArrayindexTy...somehow.
305  if (indexTy.isNull())
306    indexTy = Ctx.IntTy;
307  nonloc::ConcreteInt Min(BVF.getMinValue(indexTy));
308
309  // Adjust the index.
310  SVal newIdx = svalBuilder.evalBinOpNN(this, BO_Add,
311                                        cast<NonLoc>(Idx), Min, indexTy);
312  if (newIdx.isUnknownOrUndef())
313    return this;
314
315  // Adjust the upper bound.
316  SVal newBound =
317    svalBuilder.evalBinOpNN(this, BO_Add, cast<NonLoc>(UpperBound),
318                            Min, indexTy);
319
320  if (newBound.isUnknownOrUndef())
321    return this;
322
323  // Build the actual comparison.
324  SVal inBound = svalBuilder.evalBinOpNN(this, BO_LT,
325                                cast<NonLoc>(newIdx), cast<NonLoc>(newBound),
326                                Ctx.IntTy);
327  if (inBound.isUnknownOrUndef())
328    return this;
329
330  // Finally, let the constraint manager take care of it.
331  ConstraintManager &CM = SM.getConstraintManager();
332  return CM.assume(this, cast<DefinedSVal>(inBound), Assumption);
333}
334
335ProgramStateRef ProgramStateManager::getInitialState(const LocationContext *InitLoc) {
336  ProgramState State(this,
337                EnvMgr.getInitialEnvironment(),
338                StoreMgr->getInitialStore(InitLoc),
339                GDMFactory.getEmptyMap());
340
341  return getPersistentState(State);
342}
343
344ProgramStateRef ProgramStateManager::getPersistentStateWithGDM(
345                                                     ProgramStateRef FromState,
346                                                     ProgramStateRef GDMState) {
347  ProgramState NewState(*FromState);
348  NewState.GDM = GDMState->GDM;
349  return getPersistentState(NewState);
350}
351
352ProgramStateRef ProgramStateManager::getPersistentState(ProgramState &State) {
353
354  llvm::FoldingSetNodeID ID;
355  State.Profile(ID);
356  void *InsertPos;
357
358  if (ProgramState *I = StateSet.FindNodeOrInsertPos(ID, InsertPos))
359    return I;
360
361  ProgramState *newState = 0;
362  if (!freeStates.empty()) {
363    newState = freeStates.back();
364    freeStates.pop_back();
365  }
366  else {
367    newState = (ProgramState*) Alloc.Allocate<ProgramState>();
368  }
369  new (newState) ProgramState(State);
370  StateSet.InsertNode(newState, InsertPos);
371  return newState;
372}
373
374ProgramStateRef ProgramState::makeWithStore(const StoreRef &store) const {
375  ProgramState NewSt(*this);
376  NewSt.setStore(store);
377  return getStateManager().getPersistentState(NewSt);
378}
379
380void ProgramState::setStore(const StoreRef &newStore) {
381  Store newStoreStore = newStore.getStore();
382  if (newStoreStore)
383    stateMgr->getStoreManager().incrementReferenceCount(newStoreStore);
384  if (store)
385    stateMgr->getStoreManager().decrementReferenceCount(store);
386  store = newStoreStore;
387}
388
389//===----------------------------------------------------------------------===//
390//  State pretty-printing.
391//===----------------------------------------------------------------------===//
392
393void ProgramState::print(raw_ostream &Out,
394                         const char *NL, const char *Sep) const {
395  // Print the store.
396  ProgramStateManager &Mgr = getStateManager();
397  Mgr.getStoreManager().print(getStore(), Out, NL, Sep);
398
399  // Print out the environment.
400  Env.print(Out, NL, Sep);
401
402  // Print out the constraints.
403  Mgr.getConstraintManager().print(this, Out, NL, Sep);
404
405  // Print checker-specific data.
406  Mgr.getOwningEngine()->printState(Out, this, NL, Sep);
407}
408
409void ProgramState::printDOT(raw_ostream &Out) const {
410  print(Out, "\\l", "\\|");
411}
412
413void ProgramState::dump() const {
414  print(llvm::errs());
415}
416
417void ProgramState::printTaint(raw_ostream &Out,
418                              const char *NL, const char *Sep) const {
419  TaintMapImpl TM = get<TaintMap>();
420
421  if (!TM.isEmpty())
422    Out <<"Tainted Symbols:" << NL;
423
424  for (TaintMapImpl::iterator I = TM.begin(), E = TM.end(); I != E; ++I) {
425    Out << I->first << " : " << I->second << NL;
426  }
427}
428
429void ProgramState::dumpTaint() const {
430  printTaint(llvm::errs());
431}
432
433//===----------------------------------------------------------------------===//
434// Generic Data Map.
435//===----------------------------------------------------------------------===//
436
437void *const* ProgramState::FindGDM(void *K) const {
438  return GDM.lookup(K);
439}
440
441void*
442ProgramStateManager::FindGDMContext(void *K,
443                               void *(*CreateContext)(llvm::BumpPtrAllocator&),
444                               void (*DeleteContext)(void*)) {
445
446  std::pair<void*, void (*)(void*)>& p = GDMContexts[K];
447  if (!p.first) {
448    p.first = CreateContext(Alloc);
449    p.second = DeleteContext;
450  }
451
452  return p.first;
453}
454
455ProgramStateRef ProgramStateManager::addGDM(ProgramStateRef St, void *Key, void *Data){
456  ProgramState::GenericDataMap M1 = St->getGDM();
457  ProgramState::GenericDataMap M2 = GDMFactory.add(M1, Key, Data);
458
459  if (M1 == M2)
460    return St;
461
462  ProgramState NewSt = *St;
463  NewSt.GDM = M2;
464  return getPersistentState(NewSt);
465}
466
467ProgramStateRef ProgramStateManager::removeGDM(ProgramStateRef state, void *Key) {
468  ProgramState::GenericDataMap OldM = state->getGDM();
469  ProgramState::GenericDataMap NewM = GDMFactory.remove(OldM, Key);
470
471  if (NewM == OldM)
472    return state;
473
474  ProgramState NewState = *state;
475  NewState.GDM = NewM;
476  return getPersistentState(NewState);
477}
478
479bool ScanReachableSymbols::scan(nonloc::CompoundVal val) {
480  for (nonloc::CompoundVal::iterator I=val.begin(), E=val.end(); I!=E; ++I)
481    if (!scan(*I))
482      return false;
483
484  return true;
485}
486
487bool ScanReachableSymbols::scan(const SymExpr *sym) {
488  unsigned &isVisited = visited[sym];
489  if (isVisited)
490    return true;
491  isVisited = 1;
492
493  if (!visitor.VisitSymbol(sym))
494    return false;
495
496  // TODO: should be rewritten using SymExpr::symbol_iterator.
497  switch (sym->getKind()) {
498    case SymExpr::RegionValueKind:
499    case SymExpr::ConjuredKind:
500    case SymExpr::DerivedKind:
501    case SymExpr::ExtentKind:
502    case SymExpr::MetadataKind:
503      break;
504    case SymExpr::CastSymbolKind:
505      return scan(cast<SymbolCast>(sym)->getOperand());
506    case SymExpr::SymIntKind:
507      return scan(cast<SymIntExpr>(sym)->getLHS());
508    case SymExpr::IntSymKind:
509      return scan(cast<IntSymExpr>(sym)->getRHS());
510    case SymExpr::SymSymKind: {
511      const SymSymExpr *x = cast<SymSymExpr>(sym);
512      return scan(x->getLHS()) && scan(x->getRHS());
513    }
514  }
515  return true;
516}
517
518bool ScanReachableSymbols::scan(SVal val) {
519  if (loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(&val))
520    return scan(X->getRegion());
521
522  if (nonloc::LazyCompoundVal *X = dyn_cast<nonloc::LazyCompoundVal>(&val))
523    return scan(X->getRegion());
524
525  if (nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(&val))
526    return scan(X->getLoc());
527
528  if (SymbolRef Sym = val.getAsSymbol())
529    return scan(Sym);
530
531  if (const SymExpr *Sym = val.getAsSymbolicExpression())
532    return scan(Sym);
533
534  if (nonloc::CompoundVal *X = dyn_cast<nonloc::CompoundVal>(&val))
535    return scan(*X);
536
537  return true;
538}
539
540bool ScanReachableSymbols::scan(const MemRegion *R) {
541  if (isa<MemSpaceRegion>(R))
542    return true;
543
544  unsigned &isVisited = visited[R];
545  if (isVisited)
546    return true;
547  isVisited = 1;
548
549
550  if (!visitor.VisitMemRegion(R))
551    return false;
552
553  // If this is a symbolic region, visit the symbol for the region.
554  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
555    if (!visitor.VisitSymbol(SR->getSymbol()))
556      return false;
557
558  // If this is a subregion, also visit the parent regions.
559  if (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
560    const MemRegion *Super = SR->getSuperRegion();
561    if (!scan(Super))
562      return false;
563
564    // When we reach the topmost region, scan all symbols in it.
565    if (isa<MemSpaceRegion>(Super)) {
566      StoreManager &StoreMgr = state->getStateManager().getStoreManager();
567      if (!StoreMgr.scanReachableSymbols(state->getStore(), SR, *this))
568        return false;
569    }
570  }
571
572  // Regions captured by a block are also implicitly reachable.
573  if (const BlockDataRegion *BDR = dyn_cast<BlockDataRegion>(R)) {
574    BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(),
575                                              E = BDR->referenced_vars_end();
576    for ( ; I != E; ++I) {
577      if (!scan(I.getCapturedRegion()))
578        return false;
579    }
580  }
581
582  return true;
583}
584
585bool ProgramState::scanReachableSymbols(SVal val, SymbolVisitor& visitor) const {
586  ScanReachableSymbols S(this, visitor);
587  return S.scan(val);
588}
589
590bool ProgramState::scanReachableSymbols(const SVal *I, const SVal *E,
591                                   SymbolVisitor &visitor) const {
592  ScanReachableSymbols S(this, visitor);
593  for ( ; I != E; ++I) {
594    if (!S.scan(*I))
595      return false;
596  }
597  return true;
598}
599
600bool ProgramState::scanReachableSymbols(const MemRegion * const *I,
601                                   const MemRegion * const *E,
602                                   SymbolVisitor &visitor) const {
603  ScanReachableSymbols S(this, visitor);
604  for ( ; I != E; ++I) {
605    if (!S.scan(*I))
606      return false;
607  }
608  return true;
609}
610
611ProgramStateRef ProgramState::addTaint(const Stmt *S,
612                                           const LocationContext *LCtx,
613                                           TaintTagType Kind) const {
614  if (const Expr *E = dyn_cast_or_null<Expr>(S))
615    S = E->IgnoreParens();
616
617  SymbolRef Sym = getSVal(S, LCtx).getAsSymbol();
618  if (Sym)
619    return addTaint(Sym, Kind);
620
621  const MemRegion *R = getSVal(S, LCtx).getAsRegion();
622  addTaint(R, Kind);
623
624  // Cannot add taint, so just return the state.
625  return this;
626}
627
628ProgramStateRef ProgramState::addTaint(const MemRegion *R,
629                                           TaintTagType Kind) const {
630  if (const SymbolicRegion *SR = dyn_cast_or_null<SymbolicRegion>(R))
631    return addTaint(SR->getSymbol(), Kind);
632  return this;
633}
634
635ProgramStateRef ProgramState::addTaint(SymbolRef Sym,
636                                           TaintTagType Kind) const {
637  // If this is a symbol cast, remove the cast before adding the taint. Taint
638  // is cast agnostic.
639  while (const SymbolCast *SC = dyn_cast<SymbolCast>(Sym))
640    Sym = SC->getOperand();
641
642  ProgramStateRef NewState = set<TaintMap>(Sym, Kind);
643  assert(NewState);
644  return NewState;
645}
646
647bool ProgramState::isTainted(const Stmt *S, const LocationContext *LCtx,
648                             TaintTagType Kind) const {
649  if (const Expr *E = dyn_cast_or_null<Expr>(S))
650    S = E->IgnoreParens();
651
652  SVal val = getSVal(S, LCtx);
653  return isTainted(val, Kind);
654}
655
656bool ProgramState::isTainted(SVal V, TaintTagType Kind) const {
657  if (const SymExpr *Sym = V.getAsSymExpr())
658    return isTainted(Sym, Kind);
659  if (const MemRegion *Reg = V.getAsRegion())
660    return isTainted(Reg, Kind);
661  return false;
662}
663
664bool ProgramState::isTainted(const MemRegion *Reg, TaintTagType K) const {
665  if (!Reg)
666    return false;
667
668  // Element region (array element) is tainted if either the base or the offset
669  // are tainted.
670  if (const ElementRegion *ER = dyn_cast<ElementRegion>(Reg))
671    return isTainted(ER->getSuperRegion(), K) || isTainted(ER->getIndex(), K);
672
673  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(Reg))
674    return isTainted(SR->getSymbol(), K);
675
676  if (const SubRegion *ER = dyn_cast<SubRegion>(Reg))
677    return isTainted(ER->getSuperRegion(), K);
678
679  return false;
680}
681
682bool ProgramState::isTainted(SymbolRef Sym, TaintTagType Kind) const {
683  if (!Sym)
684    return false;
685
686  // Traverse all the symbols this symbol depends on to see if any are tainted.
687  bool Tainted = false;
688  for (SymExpr::symbol_iterator SI = Sym->symbol_begin(), SE =Sym->symbol_end();
689       SI != SE; ++SI) {
690    if (!isa<SymbolData>(*SI))
691      continue;
692
693    const TaintTagType *Tag = get<TaintMap>(*SI);
694    Tainted = (Tag && *Tag == Kind);
695
696    // If this is a SymbolDerived with a tainted parent, it's also tainted.
697    if (const SymbolDerived *SD = dyn_cast<SymbolDerived>(*SI))
698      Tainted = Tainted || isTainted(SD->getParentSymbol(), Kind);
699
700    // If memory region is tainted, data is also tainted.
701    if (const SymbolRegionValue *SRV = dyn_cast<SymbolRegionValue>(*SI))
702      Tainted = Tainted || isTainted(SRV->getRegion(), Kind);
703
704    // If If this is a SymbolCast from a tainted value, it's also tainted.
705    if (const SymbolCast *SC = dyn_cast<SymbolCast>(*SI))
706      Tainted = Tainted || isTainted(SC->getOperand(), Kind);
707
708    if (Tainted)
709      return true;
710  }
711
712  return Tainted;
713}
714
715/// The GDM component containing the dynamic type info. This is a map from a
716/// symbol to it's most likely type.
717namespace clang {
718namespace ento {
719typedef llvm::ImmutableMap<const MemRegion *, DynamicTypeInfo> DynamicTypeMap;
720template<> struct ProgramStateTrait<DynamicTypeMap>
721    : public ProgramStatePartialTrait<DynamicTypeMap> {
722  static void *GDMIndex() { static int index; return &index; }
723};
724}}
725
726DynamicTypeInfo ProgramState::getDynamicTypeInfo(const MemRegion *Reg) const {
727  Reg = Reg->StripCasts();
728
729  // Look up the dynamic type in the GDM.
730  const DynamicTypeInfo *GDMType = get<DynamicTypeMap>(Reg);
731  if (GDMType)
732    return *GDMType;
733
734  // Otherwise, fall back to what we know about the region.
735  if (const TypedRegion *TR = dyn_cast<TypedRegion>(Reg))
736    return DynamicTypeInfo(TR->getLocationType(), /*CanBeSubclass=*/false);
737
738  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(Reg)) {
739    SymbolRef Sym = SR->getSymbol();
740    return DynamicTypeInfo(Sym->getType());
741  }
742
743  return DynamicTypeInfo();
744}
745
746ProgramStateRef ProgramState::setDynamicTypeInfo(const MemRegion *Reg,
747                                                 DynamicTypeInfo NewTy) const {
748  Reg = Reg->StripCasts();
749  ProgramStateRef NewState = set<DynamicTypeMap>(Reg, NewTy);
750  assert(NewState);
751  return NewState;
752}
753