1//== RegionStore.cpp - Field-sensitive store model --------------*- 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 defines a basic region store model. In this model, we do have field
11// sensitivity. But we assume nothing about the heap shape. So recursive data
12// structures are largely ignored. Basically we do 1-limiting analysis.
13// Parameter pointers are assumed with no aliasing. Pointee objects of
14// parameters are created lazily.
15//
16//===----------------------------------------------------------------------===//
17#include "clang/AST/Attr.h"
18#include "clang/AST/CharUnits.h"
19#include "clang/Analysis/Analyses/LiveVariables.h"
20#include "clang/Analysis/AnalysisContext.h"
21#include "clang/Basic/TargetInfo.h"
22#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
23#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
24#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
25#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
26#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
27#include "clang/StaticAnalyzer/Core/PathSensitive/SubEngine.h"
28#include "llvm/ADT/ImmutableList.h"
29#include "llvm/ADT/ImmutableMap.h"
30#include "llvm/ADT/Optional.h"
31#include "llvm/Support/raw_ostream.h"
32
33using namespace clang;
34using namespace ento;
35
36//===----------------------------------------------------------------------===//
37// Representation of binding keys.
38//===----------------------------------------------------------------------===//
39
40namespace {
41class BindingKey {
42public:
43  enum Kind { Default = 0x0, Direct = 0x1 };
44private:
45  enum { Symbolic = 0x2 };
46
47  llvm::PointerIntPair<const MemRegion *, 2> P;
48  uint64_t Data;
49
50  /// Create a key for a binding to region \p r, which has a symbolic offset
51  /// from region \p Base.
52  explicit BindingKey(const SubRegion *r, const SubRegion *Base, Kind k)
53    : P(r, k | Symbolic), Data(reinterpret_cast<uintptr_t>(Base)) {
54    assert(r && Base && "Must have known regions.");
55    assert(getConcreteOffsetRegion() == Base && "Failed to store base region");
56  }
57
58  /// Create a key for a binding at \p offset from base region \p r.
59  explicit BindingKey(const MemRegion *r, uint64_t offset, Kind k)
60    : P(r, k), Data(offset) {
61    assert(r && "Must have known regions.");
62    assert(getOffset() == offset && "Failed to store offset");
63    assert((r == r->getBaseRegion() || isa<ObjCIvarRegion>(r)) && "Not a base");
64  }
65public:
66
67  bool isDirect() const { return P.getInt() & Direct; }
68  bool hasSymbolicOffset() const { return P.getInt() & Symbolic; }
69
70  const MemRegion *getRegion() const { return P.getPointer(); }
71  uint64_t getOffset() const {
72    assert(!hasSymbolicOffset());
73    return Data;
74  }
75
76  const SubRegion *getConcreteOffsetRegion() const {
77    assert(hasSymbolicOffset());
78    return reinterpret_cast<const SubRegion *>(static_cast<uintptr_t>(Data));
79  }
80
81  const MemRegion *getBaseRegion() const {
82    if (hasSymbolicOffset())
83      return getConcreteOffsetRegion()->getBaseRegion();
84    return getRegion()->getBaseRegion();
85  }
86
87  void Profile(llvm::FoldingSetNodeID& ID) const {
88    ID.AddPointer(P.getOpaqueValue());
89    ID.AddInteger(Data);
90  }
91
92  static BindingKey Make(const MemRegion *R, Kind k);
93
94  bool operator<(const BindingKey &X) const {
95    if (P.getOpaqueValue() < X.P.getOpaqueValue())
96      return true;
97    if (P.getOpaqueValue() > X.P.getOpaqueValue())
98      return false;
99    return Data < X.Data;
100  }
101
102  bool operator==(const BindingKey &X) const {
103    return P.getOpaqueValue() == X.P.getOpaqueValue() &&
104           Data == X.Data;
105  }
106
107  void dump() const;
108};
109} // end anonymous namespace
110
111BindingKey BindingKey::Make(const MemRegion *R, Kind k) {
112  const RegionOffset &RO = R->getAsOffset();
113  if (RO.hasSymbolicOffset())
114    return BindingKey(cast<SubRegion>(R), cast<SubRegion>(RO.getRegion()), k);
115
116  return BindingKey(RO.getRegion(), RO.getOffset(), k);
117}
118
119namespace llvm {
120  static inline
121  raw_ostream &operator<<(raw_ostream &os, BindingKey K) {
122    os << '(' << K.getRegion();
123    if (!K.hasSymbolicOffset())
124      os << ',' << K.getOffset();
125    os << ',' << (K.isDirect() ? "direct" : "default")
126       << ')';
127    return os;
128  }
129
130  template <typename T> struct isPodLike;
131  template <> struct isPodLike<BindingKey> {
132    static const bool value = true;
133  };
134} // end llvm namespace
135
136LLVM_DUMP_METHOD void BindingKey::dump() const { llvm::errs() << *this; }
137
138//===----------------------------------------------------------------------===//
139// Actual Store type.
140//===----------------------------------------------------------------------===//
141
142typedef llvm::ImmutableMap<BindingKey, SVal>    ClusterBindings;
143typedef llvm::ImmutableMapRef<BindingKey, SVal> ClusterBindingsRef;
144typedef std::pair<BindingKey, SVal> BindingPair;
145
146typedef llvm::ImmutableMap<const MemRegion *, ClusterBindings>
147        RegionBindings;
148
149namespace {
150class RegionBindingsRef : public llvm::ImmutableMapRef<const MemRegion *,
151                                 ClusterBindings> {
152 ClusterBindings::Factory &CBFactory;
153public:
154  typedef llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>
155          ParentTy;
156
157  RegionBindingsRef(ClusterBindings::Factory &CBFactory,
158                    const RegionBindings::TreeTy *T,
159                    RegionBindings::TreeTy::Factory *F)
160    : llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>(T, F),
161      CBFactory(CBFactory) {}
162
163  RegionBindingsRef(const ParentTy &P, ClusterBindings::Factory &CBFactory)
164    : llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>(P),
165      CBFactory(CBFactory) {}
166
167  RegionBindingsRef add(key_type_ref K, data_type_ref D) const {
168    return RegionBindingsRef(static_cast<const ParentTy*>(this)->add(K, D),
169                             CBFactory);
170  }
171
172  RegionBindingsRef remove(key_type_ref K) const {
173    return RegionBindingsRef(static_cast<const ParentTy*>(this)->remove(K),
174                             CBFactory);
175  }
176
177  RegionBindingsRef addBinding(BindingKey K, SVal V) const;
178
179  RegionBindingsRef addBinding(const MemRegion *R,
180                               BindingKey::Kind k, SVal V) const;
181
182  RegionBindingsRef &operator=(const RegionBindingsRef &X) {
183    *static_cast<ParentTy*>(this) = X;
184    return *this;
185  }
186
187  const SVal *lookup(BindingKey K) const;
188  const SVal *lookup(const MemRegion *R, BindingKey::Kind k) const;
189  const ClusterBindings *lookup(const MemRegion *R) const {
190    return static_cast<const ParentTy*>(this)->lookup(R);
191  }
192
193  RegionBindingsRef removeBinding(BindingKey K);
194
195  RegionBindingsRef removeBinding(const MemRegion *R,
196                                  BindingKey::Kind k);
197
198  RegionBindingsRef removeBinding(const MemRegion *R) {
199    return removeBinding(R, BindingKey::Direct).
200           removeBinding(R, BindingKey::Default);
201  }
202
203  Optional<SVal> getDirectBinding(const MemRegion *R) const;
204
205  /// getDefaultBinding - Returns an SVal* representing an optional default
206  ///  binding associated with a region and its subregions.
207  Optional<SVal> getDefaultBinding(const MemRegion *R) const;
208
209  /// Return the internal tree as a Store.
210  Store asStore() const {
211    return asImmutableMap().getRootWithoutRetain();
212  }
213
214  void dump(raw_ostream &OS, const char *nl) const {
215   for (iterator I = begin(), E = end(); I != E; ++I) {
216     const ClusterBindings &Cluster = I.getData();
217     for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
218          CI != CE; ++CI) {
219       OS << ' ' << CI.getKey() << " : " << CI.getData() << nl;
220     }
221     OS << nl;
222   }
223  }
224
225  LLVM_DUMP_METHOD void dump() const { dump(llvm::errs(), "\n"); }
226};
227} // end anonymous namespace
228
229typedef const RegionBindingsRef& RegionBindingsConstRef;
230
231Optional<SVal> RegionBindingsRef::getDirectBinding(const MemRegion *R) const {
232  return Optional<SVal>::create(lookup(R, BindingKey::Direct));
233}
234
235Optional<SVal> RegionBindingsRef::getDefaultBinding(const MemRegion *R) const {
236  if (R->isBoundable())
237    if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R))
238      if (TR->getValueType()->isUnionType())
239        return UnknownVal();
240
241  return Optional<SVal>::create(lookup(R, BindingKey::Default));
242}
243
244RegionBindingsRef RegionBindingsRef::addBinding(BindingKey K, SVal V) const {
245  const MemRegion *Base = K.getBaseRegion();
246
247  const ClusterBindings *ExistingCluster = lookup(Base);
248  ClusterBindings Cluster = (ExistingCluster ? *ExistingCluster
249                             : CBFactory.getEmptyMap());
250
251  ClusterBindings NewCluster = CBFactory.add(Cluster, K, V);
252  return add(Base, NewCluster);
253}
254
255
256RegionBindingsRef RegionBindingsRef::addBinding(const MemRegion *R,
257                                                BindingKey::Kind k,
258                                                SVal V) const {
259  return addBinding(BindingKey::Make(R, k), V);
260}
261
262const SVal *RegionBindingsRef::lookup(BindingKey K) const {
263  const ClusterBindings *Cluster = lookup(K.getBaseRegion());
264  if (!Cluster)
265    return nullptr;
266  return Cluster->lookup(K);
267}
268
269const SVal *RegionBindingsRef::lookup(const MemRegion *R,
270                                      BindingKey::Kind k) const {
271  return lookup(BindingKey::Make(R, k));
272}
273
274RegionBindingsRef RegionBindingsRef::removeBinding(BindingKey K) {
275  const MemRegion *Base = K.getBaseRegion();
276  const ClusterBindings *Cluster = lookup(Base);
277  if (!Cluster)
278    return *this;
279
280  ClusterBindings NewCluster = CBFactory.remove(*Cluster, K);
281  if (NewCluster.isEmpty())
282    return remove(Base);
283  return add(Base, NewCluster);
284}
285
286RegionBindingsRef RegionBindingsRef::removeBinding(const MemRegion *R,
287                                                BindingKey::Kind k){
288  return removeBinding(BindingKey::Make(R, k));
289}
290
291//===----------------------------------------------------------------------===//
292// Fine-grained control of RegionStoreManager.
293//===----------------------------------------------------------------------===//
294
295namespace {
296struct minimal_features_tag {};
297struct maximal_features_tag {};
298
299class RegionStoreFeatures {
300  bool SupportsFields;
301public:
302  RegionStoreFeatures(minimal_features_tag) :
303    SupportsFields(false) {}
304
305  RegionStoreFeatures(maximal_features_tag) :
306    SupportsFields(true) {}
307
308  void enableFields(bool t) { SupportsFields = t; }
309
310  bool supportsFields() const { return SupportsFields; }
311};
312}
313
314//===----------------------------------------------------------------------===//
315// Main RegionStore logic.
316//===----------------------------------------------------------------------===//
317
318namespace {
319class invalidateRegionsWorker;
320
321class RegionStoreManager : public StoreManager {
322public:
323  const RegionStoreFeatures Features;
324
325  RegionBindings::Factory RBFactory;
326  mutable ClusterBindings::Factory CBFactory;
327
328  typedef std::vector<SVal> SValListTy;
329private:
330  typedef llvm::DenseMap<const LazyCompoundValData *,
331                         SValListTy> LazyBindingsMapTy;
332  LazyBindingsMapTy LazyBindingsMap;
333
334  /// The largest number of fields a struct can have and still be
335  /// considered "small".
336  ///
337  /// This is currently used to decide whether or not it is worth "forcing" a
338  /// LazyCompoundVal on bind.
339  ///
340  /// This is controlled by 'region-store-small-struct-limit' option.
341  /// To disable all small-struct-dependent behavior, set the option to "0".
342  unsigned SmallStructLimit;
343
344  /// \brief A helper used to populate the work list with the given set of
345  /// regions.
346  void populateWorkList(invalidateRegionsWorker &W,
347                        ArrayRef<SVal> Values,
348                        InvalidatedRegions *TopLevelRegions);
349
350public:
351  RegionStoreManager(ProgramStateManager& mgr, const RegionStoreFeatures &f)
352    : StoreManager(mgr), Features(f),
353      RBFactory(mgr.getAllocator()), CBFactory(mgr.getAllocator()),
354      SmallStructLimit(0) {
355    if (SubEngine *Eng = StateMgr.getOwningEngine()) {
356      AnalyzerOptions &Options = Eng->getAnalysisManager().options;
357      SmallStructLimit =
358        Options.getOptionAsInteger("region-store-small-struct-limit", 2);
359    }
360  }
361
362
363  /// setImplicitDefaultValue - Set the default binding for the provided
364  ///  MemRegion to the value implicitly defined for compound literals when
365  ///  the value is not specified.
366  RegionBindingsRef setImplicitDefaultValue(RegionBindingsConstRef B,
367                                            const MemRegion *R, QualType T);
368
369  /// ArrayToPointer - Emulates the "decay" of an array to a pointer
370  ///  type.  'Array' represents the lvalue of the array being decayed
371  ///  to a pointer, and the returned SVal represents the decayed
372  ///  version of that lvalue (i.e., a pointer to the first element of
373  ///  the array).  This is called by ExprEngine when evaluating
374  ///  casts from arrays to pointers.
375  SVal ArrayToPointer(Loc Array, QualType ElementTy) override;
376
377  StoreRef getInitialStore(const LocationContext *InitLoc) override {
378    return StoreRef(RBFactory.getEmptyMap().getRootWithoutRetain(), *this);
379  }
380
381  //===-------------------------------------------------------------------===//
382  // Binding values to regions.
383  //===-------------------------------------------------------------------===//
384  RegionBindingsRef invalidateGlobalRegion(MemRegion::Kind K,
385                                           const Expr *Ex,
386                                           unsigned Count,
387                                           const LocationContext *LCtx,
388                                           RegionBindingsRef B,
389                                           InvalidatedRegions *Invalidated);
390
391  StoreRef invalidateRegions(Store store,
392                             ArrayRef<SVal> Values,
393                             const Expr *E, unsigned Count,
394                             const LocationContext *LCtx,
395                             const CallEvent *Call,
396                             InvalidatedSymbols &IS,
397                             RegionAndSymbolInvalidationTraits &ITraits,
398                             InvalidatedRegions *Invalidated,
399                             InvalidatedRegions *InvalidatedTopLevel) override;
400
401  bool scanReachableSymbols(Store S, const MemRegion *R,
402                            ScanReachableSymbols &Callbacks) override;
403
404  RegionBindingsRef removeSubRegionBindings(RegionBindingsConstRef B,
405                                            const SubRegion *R);
406
407public: // Part of public interface to class.
408
409  StoreRef Bind(Store store, Loc LV, SVal V) override {
410    return StoreRef(bind(getRegionBindings(store), LV, V).asStore(), *this);
411  }
412
413  RegionBindingsRef bind(RegionBindingsConstRef B, Loc LV, SVal V);
414
415  // BindDefault is only used to initialize a region with a default value.
416  StoreRef BindDefault(Store store, const MemRegion *R, SVal V) override {
417    RegionBindingsRef B = getRegionBindings(store);
418    assert(!B.lookup(R, BindingKey::Direct));
419
420    BindingKey Key = BindingKey::Make(R, BindingKey::Default);
421    if (B.lookup(Key)) {
422      const SubRegion *SR = cast<SubRegion>(R);
423      assert(SR->getAsOffset().getOffset() ==
424             SR->getSuperRegion()->getAsOffset().getOffset() &&
425             "A default value must come from a super-region");
426      B = removeSubRegionBindings(B, SR);
427    } else {
428      B = B.addBinding(Key, V);
429    }
430
431    return StoreRef(B.asImmutableMap().getRootWithoutRetain(), *this);
432  }
433
434  /// Attempt to extract the fields of \p LCV and bind them to the struct region
435  /// \p R.
436  ///
437  /// This path is used when it seems advantageous to "force" loading the values
438  /// within a LazyCompoundVal to bind memberwise to the struct region, rather
439  /// than using a Default binding at the base of the entire region. This is a
440  /// heuristic attempting to avoid building long chains of LazyCompoundVals.
441  ///
442  /// \returns The updated store bindings, or \c None if binding non-lazily
443  ///          would be too expensive.
444  Optional<RegionBindingsRef> tryBindSmallStruct(RegionBindingsConstRef B,
445                                                 const TypedValueRegion *R,
446                                                 const RecordDecl *RD,
447                                                 nonloc::LazyCompoundVal LCV);
448
449  /// BindStruct - Bind a compound value to a structure.
450  RegionBindingsRef bindStruct(RegionBindingsConstRef B,
451                               const TypedValueRegion* R, SVal V);
452
453  /// BindVector - Bind a compound value to a vector.
454  RegionBindingsRef bindVector(RegionBindingsConstRef B,
455                               const TypedValueRegion* R, SVal V);
456
457  RegionBindingsRef bindArray(RegionBindingsConstRef B,
458                              const TypedValueRegion* R,
459                              SVal V);
460
461  /// Clears out all bindings in the given region and assigns a new value
462  /// as a Default binding.
463  RegionBindingsRef bindAggregate(RegionBindingsConstRef B,
464                                  const TypedRegion *R,
465                                  SVal DefaultVal);
466
467  /// \brief Create a new store with the specified binding removed.
468  /// \param ST the original store, that is the basis for the new store.
469  /// \param L the location whose binding should be removed.
470  StoreRef killBinding(Store ST, Loc L) override;
471
472  void incrementReferenceCount(Store store) override {
473    getRegionBindings(store).manualRetain();
474  }
475
476  /// If the StoreManager supports it, decrement the reference count of
477  /// the specified Store object.  If the reference count hits 0, the memory
478  /// associated with the object is recycled.
479  void decrementReferenceCount(Store store) override {
480    getRegionBindings(store).manualRelease();
481  }
482
483  bool includedInBindings(Store store, const MemRegion *region) const override;
484
485  /// \brief Return the value bound to specified location in a given state.
486  ///
487  /// The high level logic for this method is this:
488  /// getBinding (L)
489  ///   if L has binding
490  ///     return L's binding
491  ///   else if L is in killset
492  ///     return unknown
493  ///   else
494  ///     if L is on stack or heap
495  ///       return undefined
496  ///     else
497  ///       return symbolic
498  SVal getBinding(Store S, Loc L, QualType T) override {
499    return getBinding(getRegionBindings(S), L, T);
500  }
501
502  SVal getBinding(RegionBindingsConstRef B, Loc L, QualType T = QualType());
503
504  SVal getBindingForElement(RegionBindingsConstRef B, const ElementRegion *R);
505
506  SVal getBindingForField(RegionBindingsConstRef B, const FieldRegion *R);
507
508  SVal getBindingForObjCIvar(RegionBindingsConstRef B, const ObjCIvarRegion *R);
509
510  SVal getBindingForVar(RegionBindingsConstRef B, const VarRegion *R);
511
512  SVal getBindingForLazySymbol(const TypedValueRegion *R);
513
514  SVal getBindingForFieldOrElementCommon(RegionBindingsConstRef B,
515                                         const TypedValueRegion *R,
516                                         QualType Ty);
517
518  SVal getLazyBinding(const SubRegion *LazyBindingRegion,
519                      RegionBindingsRef LazyBinding);
520
521  /// Get bindings for the values in a struct and return a CompoundVal, used
522  /// when doing struct copy:
523  /// struct s x, y;
524  /// x = y;
525  /// y's value is retrieved by this method.
526  SVal getBindingForStruct(RegionBindingsConstRef B, const TypedValueRegion *R);
527  SVal getBindingForArray(RegionBindingsConstRef B, const TypedValueRegion *R);
528  NonLoc createLazyBinding(RegionBindingsConstRef B, const TypedValueRegion *R);
529
530  /// Used to lazily generate derived symbols for bindings that are defined
531  /// implicitly by default bindings in a super region.
532  ///
533  /// Note that callers may need to specially handle LazyCompoundVals, which
534  /// are returned as is in case the caller needs to treat them differently.
535  Optional<SVal> getBindingForDerivedDefaultValue(RegionBindingsConstRef B,
536                                                  const MemRegion *superR,
537                                                  const TypedValueRegion *R,
538                                                  QualType Ty);
539
540  /// Get the state and region whose binding this region \p R corresponds to.
541  ///
542  /// If there is no lazy binding for \p R, the returned value will have a null
543  /// \c second. Note that a null pointer can represents a valid Store.
544  std::pair<Store, const SubRegion *>
545  findLazyBinding(RegionBindingsConstRef B, const SubRegion *R,
546                  const SubRegion *originalRegion);
547
548  /// Returns the cached set of interesting SVals contained within a lazy
549  /// binding.
550  ///
551  /// The precise value of "interesting" is determined for the purposes of
552  /// RegionStore's internal analysis. It must always contain all regions and
553  /// symbols, but may omit constants and other kinds of SVal.
554  const SValListTy &getInterestingValues(nonloc::LazyCompoundVal LCV);
555
556  //===------------------------------------------------------------------===//
557  // State pruning.
558  //===------------------------------------------------------------------===//
559
560  /// removeDeadBindings - Scans the RegionStore of 'state' for dead values.
561  ///  It returns a new Store with these values removed.
562  StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx,
563                              SymbolReaper& SymReaper) override;
564
565  //===------------------------------------------------------------------===//
566  // Region "extents".
567  //===------------------------------------------------------------------===//
568
569  // FIXME: This method will soon be eliminated; see the note in Store.h.
570  DefinedOrUnknownSVal getSizeInElements(ProgramStateRef state,
571                                         const MemRegion* R,
572                                         QualType EleTy) override;
573
574  //===------------------------------------------------------------------===//
575  // Utility methods.
576  //===------------------------------------------------------------------===//
577
578  RegionBindingsRef getRegionBindings(Store store) const {
579    return RegionBindingsRef(CBFactory,
580                             static_cast<const RegionBindings::TreeTy*>(store),
581                             RBFactory.getTreeFactory());
582  }
583
584  void print(Store store, raw_ostream &Out, const char* nl,
585             const char *sep) override;
586
587  void iterBindings(Store store, BindingsHandler& f) override {
588    RegionBindingsRef B = getRegionBindings(store);
589    for (RegionBindingsRef::iterator I = B.begin(), E = B.end(); I != E; ++I) {
590      const ClusterBindings &Cluster = I.getData();
591      for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
592           CI != CE; ++CI) {
593        const BindingKey &K = CI.getKey();
594        if (!K.isDirect())
595          continue;
596        if (const SubRegion *R = dyn_cast<SubRegion>(K.getRegion())) {
597          // FIXME: Possibly incorporate the offset?
598          if (!f.HandleBinding(*this, store, R, CI.getData()))
599            return;
600        }
601      }
602    }
603  }
604};
605
606} // end anonymous namespace
607
608//===----------------------------------------------------------------------===//
609// RegionStore creation.
610//===----------------------------------------------------------------------===//
611
612StoreManager *ento::CreateRegionStoreManager(ProgramStateManager& StMgr) {
613  RegionStoreFeatures F = maximal_features_tag();
614  return new RegionStoreManager(StMgr, F);
615}
616
617StoreManager *
618ento::CreateFieldsOnlyRegionStoreManager(ProgramStateManager &StMgr) {
619  RegionStoreFeatures F = minimal_features_tag();
620  F.enableFields(true);
621  return new RegionStoreManager(StMgr, F);
622}
623
624
625//===----------------------------------------------------------------------===//
626// Region Cluster analysis.
627//===----------------------------------------------------------------------===//
628
629namespace {
630/// Used to determine which global regions are automatically included in the
631/// initial worklist of a ClusterAnalysis.
632enum GlobalsFilterKind {
633  /// Don't include any global regions.
634  GFK_None,
635  /// Only include system globals.
636  GFK_SystemOnly,
637  /// Include all global regions.
638  GFK_All
639};
640
641template <typename DERIVED>
642class ClusterAnalysis  {
643protected:
644  typedef llvm::DenseMap<const MemRegion *, const ClusterBindings *> ClusterMap;
645  typedef const MemRegion * WorkListElement;
646  typedef SmallVector<WorkListElement, 10> WorkList;
647
648  llvm::SmallPtrSet<const ClusterBindings *, 16> Visited;
649
650  WorkList WL;
651
652  RegionStoreManager &RM;
653  ASTContext &Ctx;
654  SValBuilder &svalBuilder;
655
656  RegionBindingsRef B;
657
658private:
659  GlobalsFilterKind GlobalsFilter;
660
661protected:
662  const ClusterBindings *getCluster(const MemRegion *R) {
663    return B.lookup(R);
664  }
665
666  /// Returns true if the memory space of the given region is one of the global
667  /// regions specially included at the start of analysis.
668  bool isInitiallyIncludedGlobalRegion(const MemRegion *R) {
669    switch (GlobalsFilter) {
670    case GFK_None:
671      return false;
672    case GFK_SystemOnly:
673      return isa<GlobalSystemSpaceRegion>(R->getMemorySpace());
674    case GFK_All:
675      return isa<NonStaticGlobalSpaceRegion>(R->getMemorySpace());
676    }
677
678    llvm_unreachable("unknown globals filter");
679  }
680
681public:
682  ClusterAnalysis(RegionStoreManager &rm, ProgramStateManager &StateMgr,
683                  RegionBindingsRef b, GlobalsFilterKind GFK)
684    : RM(rm), Ctx(StateMgr.getContext()),
685      svalBuilder(StateMgr.getSValBuilder()),
686      B(b), GlobalsFilter(GFK) {}
687
688  RegionBindingsRef getRegionBindings() const { return B; }
689
690  bool isVisited(const MemRegion *R) {
691    return Visited.count(getCluster(R));
692  }
693
694  void GenerateClusters() {
695    // Scan the entire set of bindings and record the region clusters.
696    for (RegionBindingsRef::iterator RI = B.begin(), RE = B.end();
697         RI != RE; ++RI){
698      const MemRegion *Base = RI.getKey();
699
700      const ClusterBindings &Cluster = RI.getData();
701      assert(!Cluster.isEmpty() && "Empty clusters should be removed");
702      static_cast<DERIVED*>(this)->VisitAddedToCluster(Base, Cluster);
703
704      // If this is an interesting global region, add it the work list up front.
705      if (isInitiallyIncludedGlobalRegion(Base))
706        AddToWorkList(WorkListElement(Base), &Cluster);
707    }
708  }
709
710  bool AddToWorkList(WorkListElement E, const ClusterBindings *C) {
711    if (C && !Visited.insert(C))
712      return false;
713    WL.push_back(E);
714    return true;
715  }
716
717  bool AddToWorkList(const MemRegion *R) {
718    const MemRegion *BaseR = R->getBaseRegion();
719    return AddToWorkList(WorkListElement(BaseR), getCluster(BaseR));
720  }
721
722  void RunWorkList() {
723    while (!WL.empty()) {
724      WorkListElement E = WL.pop_back_val();
725      const MemRegion *BaseR = E;
726
727      static_cast<DERIVED*>(this)->VisitCluster(BaseR, getCluster(BaseR));
728    }
729  }
730
731  void VisitAddedToCluster(const MemRegion *baseR, const ClusterBindings &C) {}
732  void VisitCluster(const MemRegion *baseR, const ClusterBindings *C) {}
733
734  void VisitCluster(const MemRegion *BaseR, const ClusterBindings *C,
735                    bool Flag) {
736    static_cast<DERIVED*>(this)->VisitCluster(BaseR, C);
737  }
738};
739}
740
741//===----------------------------------------------------------------------===//
742// Binding invalidation.
743//===----------------------------------------------------------------------===//
744
745bool RegionStoreManager::scanReachableSymbols(Store S, const MemRegion *R,
746                                              ScanReachableSymbols &Callbacks) {
747  assert(R == R->getBaseRegion() && "Should only be called for base regions");
748  RegionBindingsRef B = getRegionBindings(S);
749  const ClusterBindings *Cluster = B.lookup(R);
750
751  if (!Cluster)
752    return true;
753
754  for (ClusterBindings::iterator RI = Cluster->begin(), RE = Cluster->end();
755       RI != RE; ++RI) {
756    if (!Callbacks.scan(RI.getData()))
757      return false;
758  }
759
760  return true;
761}
762
763static inline bool isUnionField(const FieldRegion *FR) {
764  return FR->getDecl()->getParent()->isUnion();
765}
766
767typedef SmallVector<const FieldDecl *, 8> FieldVector;
768
769void getSymbolicOffsetFields(BindingKey K, FieldVector &Fields) {
770  assert(K.hasSymbolicOffset() && "Not implemented for concrete offset keys");
771
772  const MemRegion *Base = K.getConcreteOffsetRegion();
773  const MemRegion *R = K.getRegion();
774
775  while (R != Base) {
776    if (const FieldRegion *FR = dyn_cast<FieldRegion>(R))
777      if (!isUnionField(FR))
778        Fields.push_back(FR->getDecl());
779
780    R = cast<SubRegion>(R)->getSuperRegion();
781  }
782}
783
784static bool isCompatibleWithFields(BindingKey K, const FieldVector &Fields) {
785  assert(K.hasSymbolicOffset() && "Not implemented for concrete offset keys");
786
787  if (Fields.empty())
788    return true;
789
790  FieldVector FieldsInBindingKey;
791  getSymbolicOffsetFields(K, FieldsInBindingKey);
792
793  ptrdiff_t Delta = FieldsInBindingKey.size() - Fields.size();
794  if (Delta >= 0)
795    return std::equal(FieldsInBindingKey.begin() + Delta,
796                      FieldsInBindingKey.end(),
797                      Fields.begin());
798  else
799    return std::equal(FieldsInBindingKey.begin(), FieldsInBindingKey.end(),
800                      Fields.begin() - Delta);
801}
802
803/// Collects all bindings in \p Cluster that may refer to bindings within
804/// \p Top.
805///
806/// Each binding is a pair whose \c first is the key (a BindingKey) and whose
807/// \c second is the value (an SVal).
808///
809/// The \p IncludeAllDefaultBindings parameter specifies whether to include
810/// default bindings that may extend beyond \p Top itself, e.g. if \p Top is
811/// an aggregate within a larger aggregate with a default binding.
812static void
813collectSubRegionBindings(SmallVectorImpl<BindingPair> &Bindings,
814                         SValBuilder &SVB, const ClusterBindings &Cluster,
815                         const SubRegion *Top, BindingKey TopKey,
816                         bool IncludeAllDefaultBindings) {
817  FieldVector FieldsInSymbolicSubregions;
818  if (TopKey.hasSymbolicOffset()) {
819    getSymbolicOffsetFields(TopKey, FieldsInSymbolicSubregions);
820    Top = cast<SubRegion>(TopKey.getConcreteOffsetRegion());
821    TopKey = BindingKey::Make(Top, BindingKey::Default);
822  }
823
824  // Find the length (in bits) of the region being invalidated.
825  uint64_t Length = UINT64_MAX;
826  SVal Extent = Top->getExtent(SVB);
827  if (Optional<nonloc::ConcreteInt> ExtentCI =
828          Extent.getAs<nonloc::ConcreteInt>()) {
829    const llvm::APSInt &ExtentInt = ExtentCI->getValue();
830    assert(ExtentInt.isNonNegative() || ExtentInt.isUnsigned());
831    // Extents are in bytes but region offsets are in bits. Be careful!
832    Length = ExtentInt.getLimitedValue() * SVB.getContext().getCharWidth();
833  } else if (const FieldRegion *FR = dyn_cast<FieldRegion>(Top)) {
834    if (FR->getDecl()->isBitField())
835      Length = FR->getDecl()->getBitWidthValue(SVB.getContext());
836  }
837
838  for (ClusterBindings::iterator I = Cluster.begin(), E = Cluster.end();
839       I != E; ++I) {
840    BindingKey NextKey = I.getKey();
841    if (NextKey.getRegion() == TopKey.getRegion()) {
842      // FIXME: This doesn't catch the case where we're really invalidating a
843      // region with a symbolic offset. Example:
844      //      R: points[i].y
845      //   Next: points[0].x
846
847      if (NextKey.getOffset() > TopKey.getOffset() &&
848          NextKey.getOffset() - TopKey.getOffset() < Length) {
849        // Case 1: The next binding is inside the region we're invalidating.
850        // Include it.
851        Bindings.push_back(*I);
852
853      } else if (NextKey.getOffset() == TopKey.getOffset()) {
854        // Case 2: The next binding is at the same offset as the region we're
855        // invalidating. In this case, we need to leave default bindings alone,
856        // since they may be providing a default value for a regions beyond what
857        // we're invalidating.
858        // FIXME: This is probably incorrect; consider invalidating an outer
859        // struct whose first field is bound to a LazyCompoundVal.
860        if (IncludeAllDefaultBindings || NextKey.isDirect())
861          Bindings.push_back(*I);
862      }
863
864    } else if (NextKey.hasSymbolicOffset()) {
865      const MemRegion *Base = NextKey.getConcreteOffsetRegion();
866      if (Top->isSubRegionOf(Base)) {
867        // Case 3: The next key is symbolic and we just changed something within
868        // its concrete region. We don't know if the binding is still valid, so
869        // we'll be conservative and include it.
870        if (IncludeAllDefaultBindings || NextKey.isDirect())
871          if (isCompatibleWithFields(NextKey, FieldsInSymbolicSubregions))
872            Bindings.push_back(*I);
873      } else if (const SubRegion *BaseSR = dyn_cast<SubRegion>(Base)) {
874        // Case 4: The next key is symbolic, but we changed a known
875        // super-region. In this case the binding is certainly included.
876        if (Top == Base || BaseSR->isSubRegionOf(Top))
877          if (isCompatibleWithFields(NextKey, FieldsInSymbolicSubregions))
878            Bindings.push_back(*I);
879      }
880    }
881  }
882}
883
884static void
885collectSubRegionBindings(SmallVectorImpl<BindingPair> &Bindings,
886                         SValBuilder &SVB, const ClusterBindings &Cluster,
887                         const SubRegion *Top, bool IncludeAllDefaultBindings) {
888  collectSubRegionBindings(Bindings, SVB, Cluster, Top,
889                           BindingKey::Make(Top, BindingKey::Default),
890                           IncludeAllDefaultBindings);
891}
892
893RegionBindingsRef
894RegionStoreManager::removeSubRegionBindings(RegionBindingsConstRef B,
895                                            const SubRegion *Top) {
896  BindingKey TopKey = BindingKey::Make(Top, BindingKey::Default);
897  const MemRegion *ClusterHead = TopKey.getBaseRegion();
898
899  if (Top == ClusterHead) {
900    // We can remove an entire cluster's bindings all in one go.
901    return B.remove(Top);
902  }
903
904  const ClusterBindings *Cluster = B.lookup(ClusterHead);
905  if (!Cluster) {
906    // If we're invalidating a region with a symbolic offset, we need to make
907    // sure we don't treat the base region as uninitialized anymore.
908    if (TopKey.hasSymbolicOffset()) {
909      const SubRegion *Concrete = TopKey.getConcreteOffsetRegion();
910      return B.addBinding(Concrete, BindingKey::Default, UnknownVal());
911    }
912    return B;
913  }
914
915  SmallVector<BindingPair, 32> Bindings;
916  collectSubRegionBindings(Bindings, svalBuilder, *Cluster, Top, TopKey,
917                           /*IncludeAllDefaultBindings=*/false);
918
919  ClusterBindingsRef Result(*Cluster, CBFactory);
920  for (SmallVectorImpl<BindingPair>::const_iterator I = Bindings.begin(),
921                                                    E = Bindings.end();
922       I != E; ++I)
923    Result = Result.remove(I->first);
924
925  // If we're invalidating a region with a symbolic offset, we need to make sure
926  // we don't treat the base region as uninitialized anymore.
927  // FIXME: This isn't very precise; see the example in
928  // collectSubRegionBindings.
929  if (TopKey.hasSymbolicOffset()) {
930    const SubRegion *Concrete = TopKey.getConcreteOffsetRegion();
931    Result = Result.add(BindingKey::Make(Concrete, BindingKey::Default),
932                        UnknownVal());
933  }
934
935  if (Result.isEmpty())
936    return B.remove(ClusterHead);
937  return B.add(ClusterHead, Result.asImmutableMap());
938}
939
940namespace {
941class invalidateRegionsWorker : public ClusterAnalysis<invalidateRegionsWorker>
942{
943  const Expr *Ex;
944  unsigned Count;
945  const LocationContext *LCtx;
946  InvalidatedSymbols &IS;
947  RegionAndSymbolInvalidationTraits &ITraits;
948  StoreManager::InvalidatedRegions *Regions;
949public:
950  invalidateRegionsWorker(RegionStoreManager &rm,
951                          ProgramStateManager &stateMgr,
952                          RegionBindingsRef b,
953                          const Expr *ex, unsigned count,
954                          const LocationContext *lctx,
955                          InvalidatedSymbols &is,
956                          RegionAndSymbolInvalidationTraits &ITraitsIn,
957                          StoreManager::InvalidatedRegions *r,
958                          GlobalsFilterKind GFK)
959    : ClusterAnalysis<invalidateRegionsWorker>(rm, stateMgr, b, GFK),
960      Ex(ex), Count(count), LCtx(lctx), IS(is), ITraits(ITraitsIn), Regions(r){}
961
962  void VisitCluster(const MemRegion *baseR, const ClusterBindings *C);
963  void VisitBinding(SVal V);
964};
965}
966
967void invalidateRegionsWorker::VisitBinding(SVal V) {
968  // A symbol?  Mark it touched by the invalidation.
969  if (SymbolRef Sym = V.getAsSymbol())
970    IS.insert(Sym);
971
972  if (const MemRegion *R = V.getAsRegion()) {
973    AddToWorkList(R);
974    return;
975  }
976
977  // Is it a LazyCompoundVal?  All references get invalidated as well.
978  if (Optional<nonloc::LazyCompoundVal> LCS =
979          V.getAs<nonloc::LazyCompoundVal>()) {
980
981    const RegionStoreManager::SValListTy &Vals = RM.getInterestingValues(*LCS);
982
983    for (RegionStoreManager::SValListTy::const_iterator I = Vals.begin(),
984                                                        E = Vals.end();
985         I != E; ++I)
986      VisitBinding(*I);
987
988    return;
989  }
990}
991
992void invalidateRegionsWorker::VisitCluster(const MemRegion *baseR,
993                                           const ClusterBindings *C) {
994
995  bool PreserveRegionsContents =
996      ITraits.hasTrait(baseR,
997                       RegionAndSymbolInvalidationTraits::TK_PreserveContents);
998
999  if (C) {
1000    for (ClusterBindings::iterator I = C->begin(), E = C->end(); I != E; ++I)
1001      VisitBinding(I.getData());
1002
1003    // Invalidate regions contents.
1004    if (!PreserveRegionsContents)
1005      B = B.remove(baseR);
1006  }
1007
1008  // BlockDataRegion?  If so, invalidate captured variables that are passed
1009  // by reference.
1010  if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(baseR)) {
1011    for (BlockDataRegion::referenced_vars_iterator
1012         BI = BR->referenced_vars_begin(), BE = BR->referenced_vars_end() ;
1013         BI != BE; ++BI) {
1014      const VarRegion *VR = BI.getCapturedRegion();
1015      const VarDecl *VD = VR->getDecl();
1016      if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage()) {
1017        AddToWorkList(VR);
1018      }
1019      else if (Loc::isLocType(VR->getValueType())) {
1020        // Map the current bindings to a Store to retrieve the value
1021        // of the binding.  If that binding itself is a region, we should
1022        // invalidate that region.  This is because a block may capture
1023        // a pointer value, but the thing pointed by that pointer may
1024        // get invalidated.
1025        SVal V = RM.getBinding(B, loc::MemRegionVal(VR));
1026        if (Optional<Loc> L = V.getAs<Loc>()) {
1027          if (const MemRegion *LR = L->getAsRegion())
1028            AddToWorkList(LR);
1029        }
1030      }
1031    }
1032    return;
1033  }
1034
1035  // Symbolic region?
1036  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(baseR))
1037    IS.insert(SR->getSymbol());
1038
1039  // Nothing else should be done in the case when we preserve regions context.
1040  if (PreserveRegionsContents)
1041    return;
1042
1043  // Otherwise, we have a normal data region. Record that we touched the region.
1044  if (Regions)
1045    Regions->push_back(baseR);
1046
1047  if (isa<AllocaRegion>(baseR) || isa<SymbolicRegion>(baseR)) {
1048    // Invalidate the region by setting its default value to
1049    // conjured symbol. The type of the symbol is irrelevant.
1050    DefinedOrUnknownSVal V =
1051      svalBuilder.conjureSymbolVal(baseR, Ex, LCtx, Ctx.IntTy, Count);
1052    B = B.addBinding(baseR, BindingKey::Default, V);
1053    return;
1054  }
1055
1056  if (!baseR->isBoundable())
1057    return;
1058
1059  const TypedValueRegion *TR = cast<TypedValueRegion>(baseR);
1060  QualType T = TR->getValueType();
1061
1062  if (isInitiallyIncludedGlobalRegion(baseR)) {
1063    // If the region is a global and we are invalidating all globals,
1064    // erasing the entry is good enough.  This causes all globals to be lazily
1065    // symbolicated from the same base symbol.
1066    return;
1067  }
1068
1069  if (T->isStructureOrClassType()) {
1070    // Invalidate the region by setting its default value to
1071    // conjured symbol. The type of the symbol is irrelevant.
1072    DefinedOrUnknownSVal V = svalBuilder.conjureSymbolVal(baseR, Ex, LCtx,
1073                                                          Ctx.IntTy, Count);
1074    B = B.addBinding(baseR, BindingKey::Default, V);
1075    return;
1076  }
1077
1078  if (const ArrayType *AT = Ctx.getAsArrayType(T)) {
1079      // Set the default value of the array to conjured symbol.
1080    DefinedOrUnknownSVal V =
1081    svalBuilder.conjureSymbolVal(baseR, Ex, LCtx,
1082                                     AT->getElementType(), Count);
1083    B = B.addBinding(baseR, BindingKey::Default, V);
1084    return;
1085  }
1086
1087  DefinedOrUnknownSVal V = svalBuilder.conjureSymbolVal(baseR, Ex, LCtx,
1088                                                        T,Count);
1089  assert(SymbolManager::canSymbolicate(T) || V.isUnknown());
1090  B = B.addBinding(baseR, BindingKey::Direct, V);
1091}
1092
1093RegionBindingsRef
1094RegionStoreManager::invalidateGlobalRegion(MemRegion::Kind K,
1095                                           const Expr *Ex,
1096                                           unsigned Count,
1097                                           const LocationContext *LCtx,
1098                                           RegionBindingsRef B,
1099                                           InvalidatedRegions *Invalidated) {
1100  // Bind the globals memory space to a new symbol that we will use to derive
1101  // the bindings for all globals.
1102  const GlobalsSpaceRegion *GS = MRMgr.getGlobalsRegion(K);
1103  SVal V = svalBuilder.conjureSymbolVal(/* SymbolTag = */ (const void*) GS, Ex, LCtx,
1104                                        /* type does not matter */ Ctx.IntTy,
1105                                        Count);
1106
1107  B = B.removeBinding(GS)
1108       .addBinding(BindingKey::Make(GS, BindingKey::Default), V);
1109
1110  // Even if there are no bindings in the global scope, we still need to
1111  // record that we touched it.
1112  if (Invalidated)
1113    Invalidated->push_back(GS);
1114
1115  return B;
1116}
1117
1118void RegionStoreManager::populateWorkList(invalidateRegionsWorker &W,
1119                                          ArrayRef<SVal> Values,
1120                                          InvalidatedRegions *TopLevelRegions) {
1121  for (ArrayRef<SVal>::iterator I = Values.begin(),
1122                                E = Values.end(); I != E; ++I) {
1123    SVal V = *I;
1124    if (Optional<nonloc::LazyCompoundVal> LCS =
1125        V.getAs<nonloc::LazyCompoundVal>()) {
1126
1127      const SValListTy &Vals = getInterestingValues(*LCS);
1128
1129      for (SValListTy::const_iterator I = Vals.begin(),
1130                                      E = Vals.end(); I != E; ++I) {
1131        // Note: the last argument is false here because these are
1132        // non-top-level regions.
1133        if (const MemRegion *R = (*I).getAsRegion())
1134          W.AddToWorkList(R);
1135      }
1136      continue;
1137    }
1138
1139    if (const MemRegion *R = V.getAsRegion()) {
1140      if (TopLevelRegions)
1141        TopLevelRegions->push_back(R);
1142      W.AddToWorkList(R);
1143      continue;
1144    }
1145  }
1146}
1147
1148StoreRef
1149RegionStoreManager::invalidateRegions(Store store,
1150                                     ArrayRef<SVal> Values,
1151                                     const Expr *Ex, unsigned Count,
1152                                     const LocationContext *LCtx,
1153                                     const CallEvent *Call,
1154                                     InvalidatedSymbols &IS,
1155                                     RegionAndSymbolInvalidationTraits &ITraits,
1156                                     InvalidatedRegions *TopLevelRegions,
1157                                     InvalidatedRegions *Invalidated) {
1158  GlobalsFilterKind GlobalsFilter;
1159  if (Call) {
1160    if (Call->isInSystemHeader())
1161      GlobalsFilter = GFK_SystemOnly;
1162    else
1163      GlobalsFilter = GFK_All;
1164  } else {
1165    GlobalsFilter = GFK_None;
1166  }
1167
1168  RegionBindingsRef B = getRegionBindings(store);
1169  invalidateRegionsWorker W(*this, StateMgr, B, Ex, Count, LCtx, IS, ITraits,
1170                            Invalidated, GlobalsFilter);
1171
1172  // Scan the bindings and generate the clusters.
1173  W.GenerateClusters();
1174
1175  // Add the regions to the worklist.
1176  populateWorkList(W, Values, TopLevelRegions);
1177
1178  W.RunWorkList();
1179
1180  // Return the new bindings.
1181  B = W.getRegionBindings();
1182
1183  // For calls, determine which global regions should be invalidated and
1184  // invalidate them. (Note that function-static and immutable globals are never
1185  // invalidated by this.)
1186  // TODO: This could possibly be more precise with modules.
1187  switch (GlobalsFilter) {
1188  case GFK_All:
1189    B = invalidateGlobalRegion(MemRegion::GlobalInternalSpaceRegionKind,
1190                               Ex, Count, LCtx, B, Invalidated);
1191    // FALLTHROUGH
1192  case GFK_SystemOnly:
1193    B = invalidateGlobalRegion(MemRegion::GlobalSystemSpaceRegionKind,
1194                               Ex, Count, LCtx, B, Invalidated);
1195    // FALLTHROUGH
1196  case GFK_None:
1197    break;
1198  }
1199
1200  return StoreRef(B.asStore(), *this);
1201}
1202
1203//===----------------------------------------------------------------------===//
1204// Extents for regions.
1205//===----------------------------------------------------------------------===//
1206
1207DefinedOrUnknownSVal
1208RegionStoreManager::getSizeInElements(ProgramStateRef state,
1209                                      const MemRegion *R,
1210                                      QualType EleTy) {
1211  SVal Size = cast<SubRegion>(R)->getExtent(svalBuilder);
1212  const llvm::APSInt *SizeInt = svalBuilder.getKnownValue(state, Size);
1213  if (!SizeInt)
1214    return UnknownVal();
1215
1216  CharUnits RegionSize = CharUnits::fromQuantity(SizeInt->getSExtValue());
1217
1218  if (Ctx.getAsVariableArrayType(EleTy)) {
1219    // FIXME: We need to track extra state to properly record the size
1220    // of VLAs.  Returning UnknownVal here, however, is a stop-gap so that
1221    // we don't have a divide-by-zero below.
1222    return UnknownVal();
1223  }
1224
1225  CharUnits EleSize = Ctx.getTypeSizeInChars(EleTy);
1226
1227  // If a variable is reinterpreted as a type that doesn't fit into a larger
1228  // type evenly, round it down.
1229  // This is a signed value, since it's used in arithmetic with signed indices.
1230  return svalBuilder.makeIntVal(RegionSize / EleSize, false);
1231}
1232
1233//===----------------------------------------------------------------------===//
1234// Location and region casting.
1235//===----------------------------------------------------------------------===//
1236
1237/// ArrayToPointer - Emulates the "decay" of an array to a pointer
1238///  type.  'Array' represents the lvalue of the array being decayed
1239///  to a pointer, and the returned SVal represents the decayed
1240///  version of that lvalue (i.e., a pointer to the first element of
1241///  the array).  This is called by ExprEngine when evaluating casts
1242///  from arrays to pointers.
1243SVal RegionStoreManager::ArrayToPointer(Loc Array, QualType T) {
1244  if (!Array.getAs<loc::MemRegionVal>())
1245    return UnknownVal();
1246
1247  const MemRegion* R = Array.castAs<loc::MemRegionVal>().getRegion();
1248  NonLoc ZeroIdx = svalBuilder.makeZeroArrayIndex();
1249  return loc::MemRegionVal(MRMgr.getElementRegion(T, ZeroIdx, R, Ctx));
1250}
1251
1252//===----------------------------------------------------------------------===//
1253// Loading values from regions.
1254//===----------------------------------------------------------------------===//
1255
1256SVal RegionStoreManager::getBinding(RegionBindingsConstRef B, Loc L, QualType T) {
1257  assert(!L.getAs<UnknownVal>() && "location unknown");
1258  assert(!L.getAs<UndefinedVal>() && "location undefined");
1259
1260  // For access to concrete addresses, return UnknownVal.  Checks
1261  // for null dereferences (and similar errors) are done by checkers, not
1262  // the Store.
1263  // FIXME: We can consider lazily symbolicating such memory, but we really
1264  // should defer this when we can reason easily about symbolicating arrays
1265  // of bytes.
1266  if (L.getAs<loc::ConcreteInt>()) {
1267    return UnknownVal();
1268  }
1269  if (!L.getAs<loc::MemRegionVal>()) {
1270    return UnknownVal();
1271  }
1272
1273  const MemRegion *MR = L.castAs<loc::MemRegionVal>().getRegion();
1274
1275  if (isa<AllocaRegion>(MR) ||
1276      isa<SymbolicRegion>(MR) ||
1277      isa<CodeTextRegion>(MR)) {
1278    if (T.isNull()) {
1279      if (const TypedRegion *TR = dyn_cast<TypedRegion>(MR))
1280        T = TR->getLocationType();
1281      else {
1282        const SymbolicRegion *SR = cast<SymbolicRegion>(MR);
1283        T = SR->getSymbol()->getType();
1284      }
1285    }
1286    MR = GetElementZeroRegion(MR, T);
1287  }
1288
1289  // FIXME: Perhaps this method should just take a 'const MemRegion*' argument
1290  //  instead of 'Loc', and have the other Loc cases handled at a higher level.
1291  const TypedValueRegion *R = cast<TypedValueRegion>(MR);
1292  QualType RTy = R->getValueType();
1293
1294  // FIXME: we do not yet model the parts of a complex type, so treat the
1295  // whole thing as "unknown".
1296  if (RTy->isAnyComplexType())
1297    return UnknownVal();
1298
1299  // FIXME: We should eventually handle funny addressing.  e.g.:
1300  //
1301  //   int x = ...;
1302  //   int *p = &x;
1303  //   char *q = (char*) p;
1304  //   char c = *q;  // returns the first byte of 'x'.
1305  //
1306  // Such funny addressing will occur due to layering of regions.
1307  if (RTy->isStructureOrClassType())
1308    return getBindingForStruct(B, R);
1309
1310  // FIXME: Handle unions.
1311  if (RTy->isUnionType())
1312    return createLazyBinding(B, R);
1313
1314  if (RTy->isArrayType()) {
1315    if (RTy->isConstantArrayType())
1316      return getBindingForArray(B, R);
1317    else
1318      return UnknownVal();
1319  }
1320
1321  // FIXME: handle Vector types.
1322  if (RTy->isVectorType())
1323    return UnknownVal();
1324
1325  if (const FieldRegion* FR = dyn_cast<FieldRegion>(R))
1326    return CastRetrievedVal(getBindingForField(B, FR), FR, T, false);
1327
1328  if (const ElementRegion* ER = dyn_cast<ElementRegion>(R)) {
1329    // FIXME: Here we actually perform an implicit conversion from the loaded
1330    // value to the element type.  Eventually we want to compose these values
1331    // more intelligently.  For example, an 'element' can encompass multiple
1332    // bound regions (e.g., several bound bytes), or could be a subset of
1333    // a larger value.
1334    return CastRetrievedVal(getBindingForElement(B, ER), ER, T, false);
1335  }
1336
1337  if (const ObjCIvarRegion *IVR = dyn_cast<ObjCIvarRegion>(R)) {
1338    // FIXME: Here we actually perform an implicit conversion from the loaded
1339    // value to the ivar type.  What we should model is stores to ivars
1340    // that blow past the extent of the ivar.  If the address of the ivar is
1341    // reinterpretted, it is possible we stored a different value that could
1342    // fit within the ivar.  Either we need to cast these when storing them
1343    // or reinterpret them lazily (as we do here).
1344    return CastRetrievedVal(getBindingForObjCIvar(B, IVR), IVR, T, false);
1345  }
1346
1347  if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
1348    // FIXME: Here we actually perform an implicit conversion from the loaded
1349    // value to the variable type.  What we should model is stores to variables
1350    // that blow past the extent of the variable.  If the address of the
1351    // variable is reinterpretted, it is possible we stored a different value
1352    // that could fit within the variable.  Either we need to cast these when
1353    // storing them or reinterpret them lazily (as we do here).
1354    return CastRetrievedVal(getBindingForVar(B, VR), VR, T, false);
1355  }
1356
1357  const SVal *V = B.lookup(R, BindingKey::Direct);
1358
1359  // Check if the region has a binding.
1360  if (V)
1361    return *V;
1362
1363  // The location does not have a bound value.  This means that it has
1364  // the value it had upon its creation and/or entry to the analyzed
1365  // function/method.  These are either symbolic values or 'undefined'.
1366  if (R->hasStackNonParametersStorage()) {
1367    // All stack variables are considered to have undefined values
1368    // upon creation.  All heap allocated blocks are considered to
1369    // have undefined values as well unless they are explicitly bound
1370    // to specific values.
1371    return UndefinedVal();
1372  }
1373
1374  // All other values are symbolic.
1375  return svalBuilder.getRegionValueSymbolVal(R);
1376}
1377
1378static QualType getUnderlyingType(const SubRegion *R) {
1379  QualType RegionTy;
1380  if (const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(R))
1381    RegionTy = TVR->getValueType();
1382
1383  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
1384    RegionTy = SR->getSymbol()->getType();
1385
1386  return RegionTy;
1387}
1388
1389/// Checks to see if store \p B has a lazy binding for region \p R.
1390///
1391/// If \p AllowSubregionBindings is \c false, a lazy binding will be rejected
1392/// if there are additional bindings within \p R.
1393///
1394/// Note that unlike RegionStoreManager::findLazyBinding, this will not search
1395/// for lazy bindings for super-regions of \p R.
1396static Optional<nonloc::LazyCompoundVal>
1397getExistingLazyBinding(SValBuilder &SVB, RegionBindingsConstRef B,
1398                       const SubRegion *R, bool AllowSubregionBindings) {
1399  Optional<SVal> V = B.getDefaultBinding(R);
1400  if (!V)
1401    return None;
1402
1403  Optional<nonloc::LazyCompoundVal> LCV = V->getAs<nonloc::LazyCompoundVal>();
1404  if (!LCV)
1405    return None;
1406
1407  // If the LCV is for a subregion, the types might not match, and we shouldn't
1408  // reuse the binding.
1409  QualType RegionTy = getUnderlyingType(R);
1410  if (!RegionTy.isNull() &&
1411      !RegionTy->isVoidPointerType()) {
1412    QualType SourceRegionTy = LCV->getRegion()->getValueType();
1413    if (!SVB.getContext().hasSameUnqualifiedType(RegionTy, SourceRegionTy))
1414      return None;
1415  }
1416
1417  if (!AllowSubregionBindings) {
1418    // If there are any other bindings within this region, we shouldn't reuse
1419    // the top-level binding.
1420    SmallVector<BindingPair, 16> Bindings;
1421    collectSubRegionBindings(Bindings, SVB, *B.lookup(R->getBaseRegion()), R,
1422                             /*IncludeAllDefaultBindings=*/true);
1423    if (Bindings.size() > 1)
1424      return None;
1425  }
1426
1427  return *LCV;
1428}
1429
1430
1431std::pair<Store, const SubRegion *>
1432RegionStoreManager::findLazyBinding(RegionBindingsConstRef B,
1433                                   const SubRegion *R,
1434                                   const SubRegion *originalRegion) {
1435  if (originalRegion != R) {
1436    if (Optional<nonloc::LazyCompoundVal> V =
1437          getExistingLazyBinding(svalBuilder, B, R, true))
1438      return std::make_pair(V->getStore(), V->getRegion());
1439  }
1440
1441  typedef std::pair<Store, const SubRegion *> StoreRegionPair;
1442  StoreRegionPair Result = StoreRegionPair();
1443
1444  if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) {
1445    Result = findLazyBinding(B, cast<SubRegion>(ER->getSuperRegion()),
1446                             originalRegion);
1447
1448    if (Result.second)
1449      Result.second = MRMgr.getElementRegionWithSuper(ER, Result.second);
1450
1451  } else if (const FieldRegion *FR = dyn_cast<FieldRegion>(R)) {
1452    Result = findLazyBinding(B, cast<SubRegion>(FR->getSuperRegion()),
1453                                       originalRegion);
1454
1455    if (Result.second)
1456      Result.second = MRMgr.getFieldRegionWithSuper(FR, Result.second);
1457
1458  } else if (const CXXBaseObjectRegion *BaseReg =
1459               dyn_cast<CXXBaseObjectRegion>(R)) {
1460    // C++ base object region is another kind of region that we should blast
1461    // through to look for lazy compound value. It is like a field region.
1462    Result = findLazyBinding(B, cast<SubRegion>(BaseReg->getSuperRegion()),
1463                             originalRegion);
1464
1465    if (Result.second)
1466      Result.second = MRMgr.getCXXBaseObjectRegionWithSuper(BaseReg,
1467                                                            Result.second);
1468  }
1469
1470  return Result;
1471}
1472
1473SVal RegionStoreManager::getBindingForElement(RegionBindingsConstRef B,
1474                                              const ElementRegion* R) {
1475  // We do not currently model bindings of the CompoundLiteralregion.
1476  if (isa<CompoundLiteralRegion>(R->getBaseRegion()))
1477    return UnknownVal();
1478
1479  // Check if the region has a binding.
1480  if (const Optional<SVal> &V = B.getDirectBinding(R))
1481    return *V;
1482
1483  const MemRegion* superR = R->getSuperRegion();
1484
1485  // Check if the region is an element region of a string literal.
1486  if (const StringRegion *StrR=dyn_cast<StringRegion>(superR)) {
1487    // FIXME: Handle loads from strings where the literal is treated as
1488    // an integer, e.g., *((unsigned int*)"hello")
1489    QualType T = Ctx.getAsArrayType(StrR->getValueType())->getElementType();
1490    if (!Ctx.hasSameUnqualifiedType(T, R->getElementType()))
1491      return UnknownVal();
1492
1493    const StringLiteral *Str = StrR->getStringLiteral();
1494    SVal Idx = R->getIndex();
1495    if (Optional<nonloc::ConcreteInt> CI = Idx.getAs<nonloc::ConcreteInt>()) {
1496      int64_t i = CI->getValue().getSExtValue();
1497      // Abort on string underrun.  This can be possible by arbitrary
1498      // clients of getBindingForElement().
1499      if (i < 0)
1500        return UndefinedVal();
1501      int64_t length = Str->getLength();
1502      // Technically, only i == length is guaranteed to be null.
1503      // However, such overflows should be caught before reaching this point;
1504      // the only time such an access would be made is if a string literal was
1505      // used to initialize a larger array.
1506      char c = (i >= length) ? '\0' : Str->getCodeUnit(i);
1507      return svalBuilder.makeIntVal(c, T);
1508    }
1509  }
1510
1511  // Check for loads from a code text region.  For such loads, just give up.
1512  if (isa<CodeTextRegion>(superR))
1513    return UnknownVal();
1514
1515  // Handle the case where we are indexing into a larger scalar object.
1516  // For example, this handles:
1517  //   int x = ...
1518  //   char *y = &x;
1519  //   return *y;
1520  // FIXME: This is a hack, and doesn't do anything really intelligent yet.
1521  const RegionRawOffset &O = R->getAsArrayOffset();
1522
1523  // If we cannot reason about the offset, return an unknown value.
1524  if (!O.getRegion())
1525    return UnknownVal();
1526
1527  if (const TypedValueRegion *baseR =
1528        dyn_cast_or_null<TypedValueRegion>(O.getRegion())) {
1529    QualType baseT = baseR->getValueType();
1530    if (baseT->isScalarType()) {
1531      QualType elemT = R->getElementType();
1532      if (elemT->isScalarType()) {
1533        if (Ctx.getTypeSizeInChars(baseT) >= Ctx.getTypeSizeInChars(elemT)) {
1534          if (const Optional<SVal> &V = B.getDirectBinding(superR)) {
1535            if (SymbolRef parentSym = V->getAsSymbol())
1536              return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
1537
1538            if (V->isUnknownOrUndef())
1539              return *V;
1540            // Other cases: give up.  We are indexing into a larger object
1541            // that has some value, but we don't know how to handle that yet.
1542            return UnknownVal();
1543          }
1544        }
1545      }
1546    }
1547  }
1548  return getBindingForFieldOrElementCommon(B, R, R->getElementType());
1549}
1550
1551SVal RegionStoreManager::getBindingForField(RegionBindingsConstRef B,
1552                                            const FieldRegion* R) {
1553
1554  // Check if the region has a binding.
1555  if (const Optional<SVal> &V = B.getDirectBinding(R))
1556    return *V;
1557
1558  QualType Ty = R->getValueType();
1559  return getBindingForFieldOrElementCommon(B, R, Ty);
1560}
1561
1562Optional<SVal>
1563RegionStoreManager::getBindingForDerivedDefaultValue(RegionBindingsConstRef B,
1564                                                     const MemRegion *superR,
1565                                                     const TypedValueRegion *R,
1566                                                     QualType Ty) {
1567
1568  if (const Optional<SVal> &D = B.getDefaultBinding(superR)) {
1569    const SVal &val = D.getValue();
1570    if (SymbolRef parentSym = val.getAsSymbol())
1571      return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
1572
1573    if (val.isZeroConstant())
1574      return svalBuilder.makeZeroVal(Ty);
1575
1576    if (val.isUnknownOrUndef())
1577      return val;
1578
1579    // Lazy bindings are usually handled through getExistingLazyBinding().
1580    // We should unify these two code paths at some point.
1581    if (val.getAs<nonloc::LazyCompoundVal>())
1582      return val;
1583
1584    llvm_unreachable("Unknown default value");
1585  }
1586
1587  return None;
1588}
1589
1590SVal RegionStoreManager::getLazyBinding(const SubRegion *LazyBindingRegion,
1591                                        RegionBindingsRef LazyBinding) {
1592  SVal Result;
1593  if (const ElementRegion *ER = dyn_cast<ElementRegion>(LazyBindingRegion))
1594    Result = getBindingForElement(LazyBinding, ER);
1595  else
1596    Result = getBindingForField(LazyBinding,
1597                                cast<FieldRegion>(LazyBindingRegion));
1598
1599  // FIXME: This is a hack to deal with RegionStore's inability to distinguish a
1600  // default value for /part/ of an aggregate from a default value for the
1601  // /entire/ aggregate. The most common case of this is when struct Outer
1602  // has as its first member a struct Inner, which is copied in from a stack
1603  // variable. In this case, even if the Outer's default value is symbolic, 0,
1604  // or unknown, it gets overridden by the Inner's default value of undefined.
1605  //
1606  // This is a general problem -- if the Inner is zero-initialized, the Outer
1607  // will now look zero-initialized. The proper way to solve this is with a
1608  // new version of RegionStore that tracks the extent of a binding as well
1609  // as the offset.
1610  //
1611  // This hack only takes care of the undefined case because that can very
1612  // quickly result in a warning.
1613  if (Result.isUndef())
1614    Result = UnknownVal();
1615
1616  return Result;
1617}
1618
1619SVal
1620RegionStoreManager::getBindingForFieldOrElementCommon(RegionBindingsConstRef B,
1621                                                      const TypedValueRegion *R,
1622                                                      QualType Ty) {
1623
1624  // At this point we have already checked in either getBindingForElement or
1625  // getBindingForField if 'R' has a direct binding.
1626
1627  // Lazy binding?
1628  Store lazyBindingStore = nullptr;
1629  const SubRegion *lazyBindingRegion = nullptr;
1630  std::tie(lazyBindingStore, lazyBindingRegion) = findLazyBinding(B, R, R);
1631  if (lazyBindingRegion)
1632    return getLazyBinding(lazyBindingRegion,
1633                          getRegionBindings(lazyBindingStore));
1634
1635  // Record whether or not we see a symbolic index.  That can completely
1636  // be out of scope of our lookup.
1637  bool hasSymbolicIndex = false;
1638
1639  // FIXME: This is a hack to deal with RegionStore's inability to distinguish a
1640  // default value for /part/ of an aggregate from a default value for the
1641  // /entire/ aggregate. The most common case of this is when struct Outer
1642  // has as its first member a struct Inner, which is copied in from a stack
1643  // variable. In this case, even if the Outer's default value is symbolic, 0,
1644  // or unknown, it gets overridden by the Inner's default value of undefined.
1645  //
1646  // This is a general problem -- if the Inner is zero-initialized, the Outer
1647  // will now look zero-initialized. The proper way to solve this is with a
1648  // new version of RegionStore that tracks the extent of a binding as well
1649  // as the offset.
1650  //
1651  // This hack only takes care of the undefined case because that can very
1652  // quickly result in a warning.
1653  bool hasPartialLazyBinding = false;
1654
1655  const SubRegion *SR = dyn_cast<SubRegion>(R);
1656  while (SR) {
1657    const MemRegion *Base = SR->getSuperRegion();
1658    if (Optional<SVal> D = getBindingForDerivedDefaultValue(B, Base, R, Ty)) {
1659      if (D->getAs<nonloc::LazyCompoundVal>()) {
1660        hasPartialLazyBinding = true;
1661        break;
1662      }
1663
1664      return *D;
1665    }
1666
1667    if (const ElementRegion *ER = dyn_cast<ElementRegion>(Base)) {
1668      NonLoc index = ER->getIndex();
1669      if (!index.isConstant())
1670        hasSymbolicIndex = true;
1671    }
1672
1673    // If our super region is a field or element itself, walk up the region
1674    // hierarchy to see if there is a default value installed in an ancestor.
1675    SR = dyn_cast<SubRegion>(Base);
1676  }
1677
1678  if (R->hasStackNonParametersStorage()) {
1679    if (isa<ElementRegion>(R)) {
1680      // Currently we don't reason specially about Clang-style vectors.  Check
1681      // if superR is a vector and if so return Unknown.
1682      if (const TypedValueRegion *typedSuperR =
1683            dyn_cast<TypedValueRegion>(R->getSuperRegion())) {
1684        if (typedSuperR->getValueType()->isVectorType())
1685          return UnknownVal();
1686      }
1687    }
1688
1689    // FIXME: We also need to take ElementRegions with symbolic indexes into
1690    // account.  This case handles both directly accessing an ElementRegion
1691    // with a symbolic offset, but also fields within an element with
1692    // a symbolic offset.
1693    if (hasSymbolicIndex)
1694      return UnknownVal();
1695
1696    if (!hasPartialLazyBinding)
1697      return UndefinedVal();
1698  }
1699
1700  // All other values are symbolic.
1701  return svalBuilder.getRegionValueSymbolVal(R);
1702}
1703
1704SVal RegionStoreManager::getBindingForObjCIvar(RegionBindingsConstRef B,
1705                                               const ObjCIvarRegion* R) {
1706  // Check if the region has a binding.
1707  if (const Optional<SVal> &V = B.getDirectBinding(R))
1708    return *V;
1709
1710  const MemRegion *superR = R->getSuperRegion();
1711
1712  // Check if the super region has a default binding.
1713  if (const Optional<SVal> &V = B.getDefaultBinding(superR)) {
1714    if (SymbolRef parentSym = V->getAsSymbol())
1715      return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
1716
1717    // Other cases: give up.
1718    return UnknownVal();
1719  }
1720
1721  return getBindingForLazySymbol(R);
1722}
1723
1724SVal RegionStoreManager::getBindingForVar(RegionBindingsConstRef B,
1725                                          const VarRegion *R) {
1726
1727  // Check if the region has a binding.
1728  if (const Optional<SVal> &V = B.getDirectBinding(R))
1729    return *V;
1730
1731  // Lazily derive a value for the VarRegion.
1732  const VarDecl *VD = R->getDecl();
1733  const MemSpaceRegion *MS = R->getMemorySpace();
1734
1735  // Arguments are always symbolic.
1736  if (isa<StackArgumentsSpaceRegion>(MS))
1737    return svalBuilder.getRegionValueSymbolVal(R);
1738
1739  // Is 'VD' declared constant?  If so, retrieve the constant value.
1740  if (VD->getType().isConstQualified())
1741    if (const Expr *Init = VD->getInit())
1742      if (Optional<SVal> V = svalBuilder.getConstantVal(Init))
1743        return *V;
1744
1745  // This must come after the check for constants because closure-captured
1746  // constant variables may appear in UnknownSpaceRegion.
1747  if (isa<UnknownSpaceRegion>(MS))
1748    return svalBuilder.getRegionValueSymbolVal(R);
1749
1750  if (isa<GlobalsSpaceRegion>(MS)) {
1751    QualType T = VD->getType();
1752
1753    // Function-scoped static variables are default-initialized to 0; if they
1754    // have an initializer, it would have been processed by now.
1755    if (isa<StaticGlobalSpaceRegion>(MS))
1756      return svalBuilder.makeZeroVal(T);
1757
1758    if (Optional<SVal> V = getBindingForDerivedDefaultValue(B, MS, R, T)) {
1759      assert(!V->getAs<nonloc::LazyCompoundVal>());
1760      return V.getValue();
1761    }
1762
1763    return svalBuilder.getRegionValueSymbolVal(R);
1764  }
1765
1766  return UndefinedVal();
1767}
1768
1769SVal RegionStoreManager::getBindingForLazySymbol(const TypedValueRegion *R) {
1770  // All other values are symbolic.
1771  return svalBuilder.getRegionValueSymbolVal(R);
1772}
1773
1774const RegionStoreManager::SValListTy &
1775RegionStoreManager::getInterestingValues(nonloc::LazyCompoundVal LCV) {
1776  // First, check the cache.
1777  LazyBindingsMapTy::iterator I = LazyBindingsMap.find(LCV.getCVData());
1778  if (I != LazyBindingsMap.end())
1779    return I->second;
1780
1781  // If we don't have a list of values cached, start constructing it.
1782  SValListTy List;
1783
1784  const SubRegion *LazyR = LCV.getRegion();
1785  RegionBindingsRef B = getRegionBindings(LCV.getStore());
1786
1787  // If this region had /no/ bindings at the time, there are no interesting
1788  // values to return.
1789  const ClusterBindings *Cluster = B.lookup(LazyR->getBaseRegion());
1790  if (!Cluster)
1791    return (LazyBindingsMap[LCV.getCVData()] = std::move(List));
1792
1793  SmallVector<BindingPair, 32> Bindings;
1794  collectSubRegionBindings(Bindings, svalBuilder, *Cluster, LazyR,
1795                           /*IncludeAllDefaultBindings=*/true);
1796  for (SmallVectorImpl<BindingPair>::const_iterator I = Bindings.begin(),
1797                                                    E = Bindings.end();
1798       I != E; ++I) {
1799    SVal V = I->second;
1800    if (V.isUnknownOrUndef() || V.isConstant())
1801      continue;
1802
1803    if (Optional<nonloc::LazyCompoundVal> InnerLCV =
1804            V.getAs<nonloc::LazyCompoundVal>()) {
1805      const SValListTy &InnerList = getInterestingValues(*InnerLCV);
1806      List.insert(List.end(), InnerList.begin(), InnerList.end());
1807      continue;
1808    }
1809
1810    List.push_back(V);
1811  }
1812
1813  return (LazyBindingsMap[LCV.getCVData()] = std::move(List));
1814}
1815
1816NonLoc RegionStoreManager::createLazyBinding(RegionBindingsConstRef B,
1817                                             const TypedValueRegion *R) {
1818  if (Optional<nonloc::LazyCompoundVal> V =
1819        getExistingLazyBinding(svalBuilder, B, R, false))
1820    return *V;
1821
1822  return svalBuilder.makeLazyCompoundVal(StoreRef(B.asStore(), *this), R);
1823}
1824
1825static bool isRecordEmpty(const RecordDecl *RD) {
1826  if (!RD->field_empty())
1827    return false;
1828  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD))
1829    return CRD->getNumBases() == 0;
1830  return true;
1831}
1832
1833SVal RegionStoreManager::getBindingForStruct(RegionBindingsConstRef B,
1834                                             const TypedValueRegion *R) {
1835  const RecordDecl *RD = R->getValueType()->castAs<RecordType>()->getDecl();
1836  if (!RD->getDefinition() || isRecordEmpty(RD))
1837    return UnknownVal();
1838
1839  return createLazyBinding(B, R);
1840}
1841
1842SVal RegionStoreManager::getBindingForArray(RegionBindingsConstRef B,
1843                                            const TypedValueRegion *R) {
1844  assert(Ctx.getAsConstantArrayType(R->getValueType()) &&
1845         "Only constant array types can have compound bindings.");
1846
1847  return createLazyBinding(B, R);
1848}
1849
1850bool RegionStoreManager::includedInBindings(Store store,
1851                                            const MemRegion *region) const {
1852  RegionBindingsRef B = getRegionBindings(store);
1853  region = region->getBaseRegion();
1854
1855  // Quick path: if the base is the head of a cluster, the region is live.
1856  if (B.lookup(region))
1857    return true;
1858
1859  // Slow path: if the region is the VALUE of any binding, it is live.
1860  for (RegionBindingsRef::iterator RI = B.begin(), RE = B.end(); RI != RE; ++RI) {
1861    const ClusterBindings &Cluster = RI.getData();
1862    for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
1863         CI != CE; ++CI) {
1864      const SVal &D = CI.getData();
1865      if (const MemRegion *R = D.getAsRegion())
1866        if (R->getBaseRegion() == region)
1867          return true;
1868    }
1869  }
1870
1871  return false;
1872}
1873
1874//===----------------------------------------------------------------------===//
1875// Binding values to regions.
1876//===----------------------------------------------------------------------===//
1877
1878StoreRef RegionStoreManager::killBinding(Store ST, Loc L) {
1879  if (Optional<loc::MemRegionVal> LV = L.getAs<loc::MemRegionVal>())
1880    if (const MemRegion* R = LV->getRegion())
1881      return StoreRef(getRegionBindings(ST).removeBinding(R)
1882                                           .asImmutableMap()
1883                                           .getRootWithoutRetain(),
1884                      *this);
1885
1886  return StoreRef(ST, *this);
1887}
1888
1889RegionBindingsRef
1890RegionStoreManager::bind(RegionBindingsConstRef B, Loc L, SVal V) {
1891  if (L.getAs<loc::ConcreteInt>())
1892    return B;
1893
1894  // If we get here, the location should be a region.
1895  const MemRegion *R = L.castAs<loc::MemRegionVal>().getRegion();
1896
1897  // Check if the region is a struct region.
1898  if (const TypedValueRegion* TR = dyn_cast<TypedValueRegion>(R)) {
1899    QualType Ty = TR->getValueType();
1900    if (Ty->isArrayType())
1901      return bindArray(B, TR, V);
1902    if (Ty->isStructureOrClassType())
1903      return bindStruct(B, TR, V);
1904    if (Ty->isVectorType())
1905      return bindVector(B, TR, V);
1906    if (Ty->isUnionType())
1907      return bindAggregate(B, TR, V);
1908  }
1909
1910  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R)) {
1911    // Binding directly to a symbolic region should be treated as binding
1912    // to element 0.
1913    QualType T = SR->getSymbol()->getType();
1914    if (T->isAnyPointerType() || T->isReferenceType())
1915      T = T->getPointeeType();
1916
1917    R = GetElementZeroRegion(SR, T);
1918  }
1919
1920  // Clear out bindings that may overlap with this binding.
1921  RegionBindingsRef NewB = removeSubRegionBindings(B, cast<SubRegion>(R));
1922  return NewB.addBinding(BindingKey::Make(R, BindingKey::Direct), V);
1923}
1924
1925RegionBindingsRef
1926RegionStoreManager::setImplicitDefaultValue(RegionBindingsConstRef B,
1927                                            const MemRegion *R,
1928                                            QualType T) {
1929  SVal V;
1930
1931  if (Loc::isLocType(T))
1932    V = svalBuilder.makeNull();
1933  else if (T->isIntegralOrEnumerationType())
1934    V = svalBuilder.makeZeroVal(T);
1935  else if (T->isStructureOrClassType() || T->isArrayType()) {
1936    // Set the default value to a zero constant when it is a structure
1937    // or array.  The type doesn't really matter.
1938    V = svalBuilder.makeZeroVal(Ctx.IntTy);
1939  }
1940  else {
1941    // We can't represent values of this type, but we still need to set a value
1942    // to record that the region has been initialized.
1943    // If this assertion ever fires, a new case should be added above -- we
1944    // should know how to default-initialize any value we can symbolicate.
1945    assert(!SymbolManager::canSymbolicate(T) && "This type is representable");
1946    V = UnknownVal();
1947  }
1948
1949  return B.addBinding(R, BindingKey::Default, V);
1950}
1951
1952RegionBindingsRef
1953RegionStoreManager::bindArray(RegionBindingsConstRef B,
1954                              const TypedValueRegion* R,
1955                              SVal Init) {
1956
1957  const ArrayType *AT =cast<ArrayType>(Ctx.getCanonicalType(R->getValueType()));
1958  QualType ElementTy = AT->getElementType();
1959  Optional<uint64_t> Size;
1960
1961  if (const ConstantArrayType* CAT = dyn_cast<ConstantArrayType>(AT))
1962    Size = CAT->getSize().getZExtValue();
1963
1964  // Check if the init expr is a string literal.
1965  if (Optional<loc::MemRegionVal> MRV = Init.getAs<loc::MemRegionVal>()) {
1966    const StringRegion *S = cast<StringRegion>(MRV->getRegion());
1967
1968    // Treat the string as a lazy compound value.
1969    StoreRef store(B.asStore(), *this);
1970    nonloc::LazyCompoundVal LCV = svalBuilder.makeLazyCompoundVal(store, S)
1971        .castAs<nonloc::LazyCompoundVal>();
1972    return bindAggregate(B, R, LCV);
1973  }
1974
1975  // Handle lazy compound values.
1976  if (Init.getAs<nonloc::LazyCompoundVal>())
1977    return bindAggregate(B, R, Init);
1978
1979  // Remaining case: explicit compound values.
1980
1981  if (Init.isUnknown())
1982    return setImplicitDefaultValue(B, R, ElementTy);
1983
1984  const nonloc::CompoundVal& CV = Init.castAs<nonloc::CompoundVal>();
1985  nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
1986  uint64_t i = 0;
1987
1988  RegionBindingsRef NewB(B);
1989
1990  for (; Size.hasValue() ? i < Size.getValue() : true ; ++i, ++VI) {
1991    // The init list might be shorter than the array length.
1992    if (VI == VE)
1993      break;
1994
1995    const NonLoc &Idx = svalBuilder.makeArrayIndex(i);
1996    const ElementRegion *ER = MRMgr.getElementRegion(ElementTy, Idx, R, Ctx);
1997
1998    if (ElementTy->isStructureOrClassType())
1999      NewB = bindStruct(NewB, ER, *VI);
2000    else if (ElementTy->isArrayType())
2001      NewB = bindArray(NewB, ER, *VI);
2002    else
2003      NewB = bind(NewB, loc::MemRegionVal(ER), *VI);
2004  }
2005
2006  // If the init list is shorter than the array length, set the
2007  // array default value.
2008  if (Size.hasValue() && i < Size.getValue())
2009    NewB = setImplicitDefaultValue(NewB, R, ElementTy);
2010
2011  return NewB;
2012}
2013
2014RegionBindingsRef RegionStoreManager::bindVector(RegionBindingsConstRef B,
2015                                                 const TypedValueRegion* R,
2016                                                 SVal V) {
2017  QualType T = R->getValueType();
2018  assert(T->isVectorType());
2019  const VectorType *VT = T->getAs<VectorType>(); // Use getAs for typedefs.
2020
2021  // Handle lazy compound values and symbolic values.
2022  if (V.getAs<nonloc::LazyCompoundVal>() || V.getAs<nonloc::SymbolVal>())
2023    return bindAggregate(B, R, V);
2024
2025  // We may get non-CompoundVal accidentally due to imprecise cast logic or
2026  // that we are binding symbolic struct value. Kill the field values, and if
2027  // the value is symbolic go and bind it as a "default" binding.
2028  if (!V.getAs<nonloc::CompoundVal>()) {
2029    return bindAggregate(B, R, UnknownVal());
2030  }
2031
2032  QualType ElemType = VT->getElementType();
2033  nonloc::CompoundVal CV = V.castAs<nonloc::CompoundVal>();
2034  nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
2035  unsigned index = 0, numElements = VT->getNumElements();
2036  RegionBindingsRef NewB(B);
2037
2038  for ( ; index != numElements ; ++index) {
2039    if (VI == VE)
2040      break;
2041
2042    NonLoc Idx = svalBuilder.makeArrayIndex(index);
2043    const ElementRegion *ER = MRMgr.getElementRegion(ElemType, Idx, R, Ctx);
2044
2045    if (ElemType->isArrayType())
2046      NewB = bindArray(NewB, ER, *VI);
2047    else if (ElemType->isStructureOrClassType())
2048      NewB = bindStruct(NewB, ER, *VI);
2049    else
2050      NewB = bind(NewB, loc::MemRegionVal(ER), *VI);
2051  }
2052  return NewB;
2053}
2054
2055Optional<RegionBindingsRef>
2056RegionStoreManager::tryBindSmallStruct(RegionBindingsConstRef B,
2057                                       const TypedValueRegion *R,
2058                                       const RecordDecl *RD,
2059                                       nonloc::LazyCompoundVal LCV) {
2060  FieldVector Fields;
2061
2062  if (const CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(RD))
2063    if (Class->getNumBases() != 0 || Class->getNumVBases() != 0)
2064      return None;
2065
2066  for (const auto *FD : RD->fields()) {
2067    if (FD->isUnnamedBitfield())
2068      continue;
2069
2070    // If there are too many fields, or if any of the fields are aggregates,
2071    // just use the LCV as a default binding.
2072    if (Fields.size() == SmallStructLimit)
2073      return None;
2074
2075    QualType Ty = FD->getType();
2076    if (!(Ty->isScalarType() || Ty->isReferenceType()))
2077      return None;
2078
2079    Fields.push_back(FD);
2080  }
2081
2082  RegionBindingsRef NewB = B;
2083
2084  for (FieldVector::iterator I = Fields.begin(), E = Fields.end(); I != E; ++I){
2085    const FieldRegion *SourceFR = MRMgr.getFieldRegion(*I, LCV.getRegion());
2086    SVal V = getBindingForField(getRegionBindings(LCV.getStore()), SourceFR);
2087
2088    const FieldRegion *DestFR = MRMgr.getFieldRegion(*I, R);
2089    NewB = bind(NewB, loc::MemRegionVal(DestFR), V);
2090  }
2091
2092  return NewB;
2093}
2094
2095RegionBindingsRef RegionStoreManager::bindStruct(RegionBindingsConstRef B,
2096                                                 const TypedValueRegion* R,
2097                                                 SVal V) {
2098  if (!Features.supportsFields())
2099    return B;
2100
2101  QualType T = R->getValueType();
2102  assert(T->isStructureOrClassType());
2103
2104  const RecordType* RT = T->getAs<RecordType>();
2105  const RecordDecl *RD = RT->getDecl();
2106
2107  if (!RD->isCompleteDefinition())
2108    return B;
2109
2110  // Handle lazy compound values and symbolic values.
2111  if (Optional<nonloc::LazyCompoundVal> LCV =
2112        V.getAs<nonloc::LazyCompoundVal>()) {
2113    if (Optional<RegionBindingsRef> NewB = tryBindSmallStruct(B, R, RD, *LCV))
2114      return *NewB;
2115    return bindAggregate(B, R, V);
2116  }
2117  if (V.getAs<nonloc::SymbolVal>())
2118    return bindAggregate(B, R, V);
2119
2120  // We may get non-CompoundVal accidentally due to imprecise cast logic or
2121  // that we are binding symbolic struct value. Kill the field values, and if
2122  // the value is symbolic go and bind it as a "default" binding.
2123  if (V.isUnknown() || !V.getAs<nonloc::CompoundVal>())
2124    return bindAggregate(B, R, UnknownVal());
2125
2126  const nonloc::CompoundVal& CV = V.castAs<nonloc::CompoundVal>();
2127  nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
2128
2129  RecordDecl::field_iterator FI, FE;
2130  RegionBindingsRef NewB(B);
2131
2132  for (FI = RD->field_begin(), FE = RD->field_end(); FI != FE; ++FI) {
2133
2134    if (VI == VE)
2135      break;
2136
2137    // Skip any unnamed bitfields to stay in sync with the initializers.
2138    if (FI->isUnnamedBitfield())
2139      continue;
2140
2141    QualType FTy = FI->getType();
2142    const FieldRegion* FR = MRMgr.getFieldRegion(*FI, R);
2143
2144    if (FTy->isArrayType())
2145      NewB = bindArray(NewB, FR, *VI);
2146    else if (FTy->isStructureOrClassType())
2147      NewB = bindStruct(NewB, FR, *VI);
2148    else
2149      NewB = bind(NewB, loc::MemRegionVal(FR), *VI);
2150    ++VI;
2151  }
2152
2153  // There may be fewer values in the initialize list than the fields of struct.
2154  if (FI != FE) {
2155    NewB = NewB.addBinding(R, BindingKey::Default,
2156                           svalBuilder.makeIntVal(0, false));
2157  }
2158
2159  return NewB;
2160}
2161
2162RegionBindingsRef
2163RegionStoreManager::bindAggregate(RegionBindingsConstRef B,
2164                                  const TypedRegion *R,
2165                                  SVal Val) {
2166  // Remove the old bindings, using 'R' as the root of all regions
2167  // we will invalidate. Then add the new binding.
2168  return removeSubRegionBindings(B, R).addBinding(R, BindingKey::Default, Val);
2169}
2170
2171//===----------------------------------------------------------------------===//
2172// State pruning.
2173//===----------------------------------------------------------------------===//
2174
2175namespace {
2176class removeDeadBindingsWorker :
2177  public ClusterAnalysis<removeDeadBindingsWorker> {
2178  SmallVector<const SymbolicRegion*, 12> Postponed;
2179  SymbolReaper &SymReaper;
2180  const StackFrameContext *CurrentLCtx;
2181
2182public:
2183  removeDeadBindingsWorker(RegionStoreManager &rm,
2184                           ProgramStateManager &stateMgr,
2185                           RegionBindingsRef b, SymbolReaper &symReaper,
2186                           const StackFrameContext *LCtx)
2187    : ClusterAnalysis<removeDeadBindingsWorker>(rm, stateMgr, b, GFK_None),
2188      SymReaper(symReaper), CurrentLCtx(LCtx) {}
2189
2190  // Called by ClusterAnalysis.
2191  void VisitAddedToCluster(const MemRegion *baseR, const ClusterBindings &C);
2192  void VisitCluster(const MemRegion *baseR, const ClusterBindings *C);
2193  using ClusterAnalysis<removeDeadBindingsWorker>::VisitCluster;
2194
2195  bool UpdatePostponed();
2196  void VisitBinding(SVal V);
2197};
2198}
2199
2200void removeDeadBindingsWorker::VisitAddedToCluster(const MemRegion *baseR,
2201                                                   const ClusterBindings &C) {
2202
2203  if (const VarRegion *VR = dyn_cast<VarRegion>(baseR)) {
2204    if (SymReaper.isLive(VR))
2205      AddToWorkList(baseR, &C);
2206
2207    return;
2208  }
2209
2210  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(baseR)) {
2211    if (SymReaper.isLive(SR->getSymbol()))
2212      AddToWorkList(SR, &C);
2213    else
2214      Postponed.push_back(SR);
2215
2216    return;
2217  }
2218
2219  if (isa<NonStaticGlobalSpaceRegion>(baseR)) {
2220    AddToWorkList(baseR, &C);
2221    return;
2222  }
2223
2224  // CXXThisRegion in the current or parent location context is live.
2225  if (const CXXThisRegion *TR = dyn_cast<CXXThisRegion>(baseR)) {
2226    const StackArgumentsSpaceRegion *StackReg =
2227      cast<StackArgumentsSpaceRegion>(TR->getSuperRegion());
2228    const StackFrameContext *RegCtx = StackReg->getStackFrame();
2229    if (CurrentLCtx &&
2230        (RegCtx == CurrentLCtx || RegCtx->isParentOf(CurrentLCtx)))
2231      AddToWorkList(TR, &C);
2232  }
2233}
2234
2235void removeDeadBindingsWorker::VisitCluster(const MemRegion *baseR,
2236                                            const ClusterBindings *C) {
2237  if (!C)
2238    return;
2239
2240  // Mark the symbol for any SymbolicRegion with live bindings as live itself.
2241  // This means we should continue to track that symbol.
2242  if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(baseR))
2243    SymReaper.markLive(SymR->getSymbol());
2244
2245  for (ClusterBindings::iterator I = C->begin(), E = C->end(); I != E; ++I)
2246    VisitBinding(I.getData());
2247}
2248
2249void removeDeadBindingsWorker::VisitBinding(SVal V) {
2250  // Is it a LazyCompoundVal?  All referenced regions are live as well.
2251  if (Optional<nonloc::LazyCompoundVal> LCS =
2252          V.getAs<nonloc::LazyCompoundVal>()) {
2253
2254    const RegionStoreManager::SValListTy &Vals = RM.getInterestingValues(*LCS);
2255
2256    for (RegionStoreManager::SValListTy::const_iterator I = Vals.begin(),
2257                                                        E = Vals.end();
2258         I != E; ++I)
2259      VisitBinding(*I);
2260
2261    return;
2262  }
2263
2264  // If V is a region, then add it to the worklist.
2265  if (const MemRegion *R = V.getAsRegion()) {
2266    AddToWorkList(R);
2267
2268    // All regions captured by a block are also live.
2269    if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(R)) {
2270      BlockDataRegion::referenced_vars_iterator I = BR->referenced_vars_begin(),
2271                                                E = BR->referenced_vars_end();
2272      for ( ; I != E; ++I)
2273        AddToWorkList(I.getCapturedRegion());
2274    }
2275  }
2276
2277
2278  // Update the set of live symbols.
2279  for (SymExpr::symbol_iterator SI = V.symbol_begin(), SE = V.symbol_end();
2280       SI!=SE; ++SI)
2281    SymReaper.markLive(*SI);
2282}
2283
2284bool removeDeadBindingsWorker::UpdatePostponed() {
2285  // See if any postponed SymbolicRegions are actually live now, after
2286  // having done a scan.
2287  bool changed = false;
2288
2289  for (SmallVectorImpl<const SymbolicRegion*>::iterator
2290        I = Postponed.begin(), E = Postponed.end() ; I != E ; ++I) {
2291    if (const SymbolicRegion *SR = *I) {
2292      if (SymReaper.isLive(SR->getSymbol())) {
2293        changed |= AddToWorkList(SR);
2294        *I = nullptr;
2295      }
2296    }
2297  }
2298
2299  return changed;
2300}
2301
2302StoreRef RegionStoreManager::removeDeadBindings(Store store,
2303                                                const StackFrameContext *LCtx,
2304                                                SymbolReaper& SymReaper) {
2305  RegionBindingsRef B = getRegionBindings(store);
2306  removeDeadBindingsWorker W(*this, StateMgr, B, SymReaper, LCtx);
2307  W.GenerateClusters();
2308
2309  // Enqueue the region roots onto the worklist.
2310  for (SymbolReaper::region_iterator I = SymReaper.region_begin(),
2311       E = SymReaper.region_end(); I != E; ++I) {
2312    W.AddToWorkList(*I);
2313  }
2314
2315  do W.RunWorkList(); while (W.UpdatePostponed());
2316
2317  // We have now scanned the store, marking reachable regions and symbols
2318  // as live.  We now remove all the regions that are dead from the store
2319  // as well as update DSymbols with the set symbols that are now dead.
2320  for (RegionBindingsRef::iterator I = B.begin(), E = B.end(); I != E; ++I) {
2321    const MemRegion *Base = I.getKey();
2322
2323    // If the cluster has been visited, we know the region has been marked.
2324    if (W.isVisited(Base))
2325      continue;
2326
2327    // Remove the dead entry.
2328    B = B.remove(Base);
2329
2330    if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(Base))
2331      SymReaper.maybeDead(SymR->getSymbol());
2332
2333    // Mark all non-live symbols that this binding references as dead.
2334    const ClusterBindings &Cluster = I.getData();
2335    for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
2336         CI != CE; ++CI) {
2337      SVal X = CI.getData();
2338      SymExpr::symbol_iterator SI = X.symbol_begin(), SE = X.symbol_end();
2339      for (; SI != SE; ++SI)
2340        SymReaper.maybeDead(*SI);
2341    }
2342  }
2343
2344  return StoreRef(B.asStore(), *this);
2345}
2346
2347//===----------------------------------------------------------------------===//
2348// Utility methods.
2349//===----------------------------------------------------------------------===//
2350
2351void RegionStoreManager::print(Store store, raw_ostream &OS,
2352                               const char* nl, const char *sep) {
2353  RegionBindingsRef B = getRegionBindings(store);
2354  OS << "Store (direct and default bindings), "
2355     << B.asStore()
2356     << " :" << nl;
2357  B.dump(OS, nl);
2358}
2359