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      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 
     33 using namespace clang;
     34 using namespace ento;
     35 
     36 //===----------------------------------------------------------------------===//
     37 // Representation of binding keys.
     38 //===----------------------------------------------------------------------===//
     39 
     40 namespace {
     41 class BindingKey {
     42 public:
     43   enum Kind { Default = 0x0, Direct = 0x1 };
     44 private:
     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   }
     65 public:
     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 
    111 BindingKey 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 
    119 namespace 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 
    136 LLVM_DUMP_METHOD void BindingKey::dump() const { llvm::errs() << *this; }
    137 
    138 //===----------------------------------------------------------------------===//
    139 // Actual Store type.
    140 //===----------------------------------------------------------------------===//
    141 
    142 typedef llvm::ImmutableMap<BindingKey, SVal>    ClusterBindings;
    143 typedef llvm::ImmutableMapRef<BindingKey, SVal> ClusterBindingsRef;
    144 typedef std::pair<BindingKey, SVal> BindingPair;
    145 
    146 typedef llvm::ImmutableMap<const MemRegion *, ClusterBindings>
    147         RegionBindings;
    148 
    149 namespace {
    150 class RegionBindingsRef : public llvm::ImmutableMapRef<const MemRegion *,
    151                                  ClusterBindings> {
    152   ClusterBindings::Factory *CBFactory;
    153 
    154 public:
    155   typedef llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>
    156           ParentTy;
    157 
    158   RegionBindingsRef(ClusterBindings::Factory &CBFactory,
    159                     const RegionBindings::TreeTy *T,
    160                     RegionBindings::TreeTy::Factory *F)
    161       : llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>(T, F),
    162         CBFactory(&CBFactory) {}
    163 
    164   RegionBindingsRef(const ParentTy &P, ClusterBindings::Factory &CBFactory)
    165       : llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>(P),
    166         CBFactory(&CBFactory) {}
    167 
    168   RegionBindingsRef add(key_type_ref K, data_type_ref D) const {
    169     return RegionBindingsRef(static_cast<const ParentTy *>(this)->add(K, D),
    170                              *CBFactory);
    171   }
    172 
    173   RegionBindingsRef remove(key_type_ref K) const {
    174     return RegionBindingsRef(static_cast<const ParentTy *>(this)->remove(K),
    175                              *CBFactory);
    176   }
    177 
    178   RegionBindingsRef addBinding(BindingKey K, SVal V) const;
    179 
    180   RegionBindingsRef addBinding(const MemRegion *R,
    181                                BindingKey::Kind k, SVal V) const;
    182 
    183   const SVal *lookup(BindingKey K) const;
    184   const SVal *lookup(const MemRegion *R, BindingKey::Kind k) const;
    185   using llvm::ImmutableMapRef<const MemRegion *, ClusterBindings>::lookup;
    186 
    187   RegionBindingsRef removeBinding(BindingKey K);
    188 
    189   RegionBindingsRef removeBinding(const MemRegion *R,
    190                                   BindingKey::Kind k);
    191 
    192   RegionBindingsRef removeBinding(const MemRegion *R) {
    193     return removeBinding(R, BindingKey::Direct).
    194            removeBinding(R, BindingKey::Default);
    195   }
    196 
    197   Optional<SVal> getDirectBinding(const MemRegion *R) const;
    198 
    199   /// getDefaultBinding - Returns an SVal* representing an optional default
    200   ///  binding associated with a region and its subregions.
    201   Optional<SVal> getDefaultBinding(const MemRegion *R) const;
    202 
    203   /// Return the internal tree as a Store.
    204   Store asStore() const {
    205     return asImmutableMap().getRootWithoutRetain();
    206   }
    207 
    208   void dump(raw_ostream &OS, const char *nl) const {
    209    for (iterator I = begin(), E = end(); I != E; ++I) {
    210      const ClusterBindings &Cluster = I.getData();
    211      for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
    212           CI != CE; ++CI) {
    213        OS << ' ' << CI.getKey() << " : " << CI.getData() << nl;
    214      }
    215      OS << nl;
    216    }
    217   }
    218 
    219   LLVM_DUMP_METHOD void dump() const { dump(llvm::errs(), "\n"); }
    220 };
    221 } // end anonymous namespace
    222 
    223 typedef const RegionBindingsRef& RegionBindingsConstRef;
    224 
    225 Optional<SVal> RegionBindingsRef::getDirectBinding(const MemRegion *R) const {
    226   return Optional<SVal>::create(lookup(R, BindingKey::Direct));
    227 }
    228 
    229 Optional<SVal> RegionBindingsRef::getDefaultBinding(const MemRegion *R) const {
    230   if (R->isBoundable())
    231     if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R))
    232       if (TR->getValueType()->isUnionType())
    233         return UnknownVal();
    234 
    235   return Optional<SVal>::create(lookup(R, BindingKey::Default));
    236 }
    237 
    238 RegionBindingsRef RegionBindingsRef::addBinding(BindingKey K, SVal V) const {
    239   const MemRegion *Base = K.getBaseRegion();
    240 
    241   const ClusterBindings *ExistingCluster = lookup(Base);
    242   ClusterBindings Cluster =
    243       (ExistingCluster ? *ExistingCluster : CBFactory->getEmptyMap());
    244 
    245   ClusterBindings NewCluster = CBFactory->add(Cluster, K, V);
    246   return add(Base, NewCluster);
    247 }
    248 
    249 
    250 RegionBindingsRef RegionBindingsRef::addBinding(const MemRegion *R,
    251                                                 BindingKey::Kind k,
    252                                                 SVal V) const {
    253   return addBinding(BindingKey::Make(R, k), V);
    254 }
    255 
    256 const SVal *RegionBindingsRef::lookup(BindingKey K) const {
    257   const ClusterBindings *Cluster = lookup(K.getBaseRegion());
    258   if (!Cluster)
    259     return nullptr;
    260   return Cluster->lookup(K);
    261 }
    262 
    263 const SVal *RegionBindingsRef::lookup(const MemRegion *R,
    264                                       BindingKey::Kind k) const {
    265   return lookup(BindingKey::Make(R, k));
    266 }
    267 
    268 RegionBindingsRef RegionBindingsRef::removeBinding(BindingKey K) {
    269   const MemRegion *Base = K.getBaseRegion();
    270   const ClusterBindings *Cluster = lookup(Base);
    271   if (!Cluster)
    272     return *this;
    273 
    274   ClusterBindings NewCluster = CBFactory->remove(*Cluster, K);
    275   if (NewCluster.isEmpty())
    276     return remove(Base);
    277   return add(Base, NewCluster);
    278 }
    279 
    280 RegionBindingsRef RegionBindingsRef::removeBinding(const MemRegion *R,
    281                                                 BindingKey::Kind k){
    282   return removeBinding(BindingKey::Make(R, k));
    283 }
    284 
    285 //===----------------------------------------------------------------------===//
    286 // Fine-grained control of RegionStoreManager.
    287 //===----------------------------------------------------------------------===//
    288 
    289 namespace {
    290 struct minimal_features_tag {};
    291 struct maximal_features_tag {};
    292 
    293 class RegionStoreFeatures {
    294   bool SupportsFields;
    295 public:
    296   RegionStoreFeatures(minimal_features_tag) :
    297     SupportsFields(false) {}
    298 
    299   RegionStoreFeatures(maximal_features_tag) :
    300     SupportsFields(true) {}
    301 
    302   void enableFields(bool t) { SupportsFields = t; }
    303 
    304   bool supportsFields() const { return SupportsFields; }
    305 };
    306 }
    307 
    308 //===----------------------------------------------------------------------===//
    309 // Main RegionStore logic.
    310 //===----------------------------------------------------------------------===//
    311 
    312 namespace {
    313 class invalidateRegionsWorker;
    314 
    315 class RegionStoreManager : public StoreManager {
    316 public:
    317   const RegionStoreFeatures Features;
    318 
    319   RegionBindings::Factory RBFactory;
    320   mutable ClusterBindings::Factory CBFactory;
    321 
    322   typedef std::vector<SVal> SValListTy;
    323 private:
    324   typedef llvm::DenseMap<const LazyCompoundValData *,
    325                          SValListTy> LazyBindingsMapTy;
    326   LazyBindingsMapTy LazyBindingsMap;
    327 
    328   /// The largest number of fields a struct can have and still be
    329   /// considered "small".
    330   ///
    331   /// This is currently used to decide whether or not it is worth "forcing" a
    332   /// LazyCompoundVal on bind.
    333   ///
    334   /// This is controlled by 'region-store-small-struct-limit' option.
    335   /// To disable all small-struct-dependent behavior, set the option to "0".
    336   unsigned SmallStructLimit;
    337 
    338   /// \brief A helper used to populate the work list with the given set of
    339   /// regions.
    340   void populateWorkList(invalidateRegionsWorker &W,
    341                         ArrayRef<SVal> Values,
    342                         InvalidatedRegions *TopLevelRegions);
    343 
    344 public:
    345   RegionStoreManager(ProgramStateManager& mgr, const RegionStoreFeatures &f)
    346     : StoreManager(mgr), Features(f),
    347       RBFactory(mgr.getAllocator()), CBFactory(mgr.getAllocator()),
    348       SmallStructLimit(0) {
    349     if (SubEngine *Eng = StateMgr.getOwningEngine()) {
    350       AnalyzerOptions &Options = Eng->getAnalysisManager().options;
    351       SmallStructLimit =
    352         Options.getOptionAsInteger("region-store-small-struct-limit", 2);
    353     }
    354   }
    355 
    356 
    357   /// setImplicitDefaultValue - Set the default binding for the provided
    358   ///  MemRegion to the value implicitly defined for compound literals when
    359   ///  the value is not specified.
    360   RegionBindingsRef setImplicitDefaultValue(RegionBindingsConstRef B,
    361                                             const MemRegion *R, QualType T);
    362 
    363   /// ArrayToPointer - Emulates the "decay" of an array to a pointer
    364   ///  type.  'Array' represents the lvalue of the array being decayed
    365   ///  to a pointer, and the returned SVal represents the decayed
    366   ///  version of that lvalue (i.e., a pointer to the first element of
    367   ///  the array).  This is called by ExprEngine when evaluating
    368   ///  casts from arrays to pointers.
    369   SVal ArrayToPointer(Loc Array, QualType ElementTy) override;
    370 
    371   StoreRef getInitialStore(const LocationContext *InitLoc) override {
    372     return StoreRef(RBFactory.getEmptyMap().getRootWithoutRetain(), *this);
    373   }
    374 
    375   //===-------------------------------------------------------------------===//
    376   // Binding values to regions.
    377   //===-------------------------------------------------------------------===//
    378   RegionBindingsRef invalidateGlobalRegion(MemRegion::Kind K,
    379                                            const Expr *Ex,
    380                                            unsigned Count,
    381                                            const LocationContext *LCtx,
    382                                            RegionBindingsRef B,
    383                                            InvalidatedRegions *Invalidated);
    384 
    385   StoreRef invalidateRegions(Store store,
    386                              ArrayRef<SVal> Values,
    387                              const Expr *E, unsigned Count,
    388                              const LocationContext *LCtx,
    389                              const CallEvent *Call,
    390                              InvalidatedSymbols &IS,
    391                              RegionAndSymbolInvalidationTraits &ITraits,
    392                              InvalidatedRegions *Invalidated,
    393                              InvalidatedRegions *InvalidatedTopLevel) override;
    394 
    395   bool scanReachableSymbols(Store S, const MemRegion *R,
    396                             ScanReachableSymbols &Callbacks) override;
    397 
    398   RegionBindingsRef removeSubRegionBindings(RegionBindingsConstRef B,
    399                                             const SubRegion *R);
    400 
    401 public: // Part of public interface to class.
    402 
    403   StoreRef Bind(Store store, Loc LV, SVal V) override {
    404     return StoreRef(bind(getRegionBindings(store), LV, V).asStore(), *this);
    405   }
    406 
    407   RegionBindingsRef bind(RegionBindingsConstRef B, Loc LV, SVal V);
    408 
    409   // BindDefault is only used to initialize a region with a default value.
    410   StoreRef BindDefault(Store store, const MemRegion *R, SVal V) override {
    411     RegionBindingsRef B = getRegionBindings(store);
    412     assert(!B.lookup(R, BindingKey::Direct));
    413 
    414     BindingKey Key = BindingKey::Make(R, BindingKey::Default);
    415     if (B.lookup(Key)) {
    416       const SubRegion *SR = cast<SubRegion>(R);
    417       assert(SR->getAsOffset().getOffset() ==
    418              SR->getSuperRegion()->getAsOffset().getOffset() &&
    419              "A default value must come from a super-region");
    420       B = removeSubRegionBindings(B, SR);
    421     } else {
    422       B = B.addBinding(Key, V);
    423     }
    424 
    425     return StoreRef(B.asImmutableMap().getRootWithoutRetain(), *this);
    426   }
    427 
    428   /// Attempt to extract the fields of \p LCV and bind them to the struct region
    429   /// \p R.
    430   ///
    431   /// This path is used when it seems advantageous to "force" loading the values
    432   /// within a LazyCompoundVal to bind memberwise to the struct region, rather
    433   /// than using a Default binding at the base of the entire region. This is a
    434   /// heuristic attempting to avoid building long chains of LazyCompoundVals.
    435   ///
    436   /// \returns The updated store bindings, or \c None if binding non-lazily
    437   ///          would be too expensive.
    438   Optional<RegionBindingsRef> tryBindSmallStruct(RegionBindingsConstRef B,
    439                                                  const TypedValueRegion *R,
    440                                                  const RecordDecl *RD,
    441                                                  nonloc::LazyCompoundVal LCV);
    442 
    443   /// BindStruct - Bind a compound value to a structure.
    444   RegionBindingsRef bindStruct(RegionBindingsConstRef B,
    445                                const TypedValueRegion* R, SVal V);
    446 
    447   /// BindVector - Bind a compound value to a vector.
    448   RegionBindingsRef bindVector(RegionBindingsConstRef B,
    449                                const TypedValueRegion* R, SVal V);
    450 
    451   RegionBindingsRef bindArray(RegionBindingsConstRef B,
    452                               const TypedValueRegion* R,
    453                               SVal V);
    454 
    455   /// Clears out all bindings in the given region and assigns a new value
    456   /// as a Default binding.
    457   RegionBindingsRef bindAggregate(RegionBindingsConstRef B,
    458                                   const TypedRegion *R,
    459                                   SVal DefaultVal);
    460 
    461   /// \brief Create a new store with the specified binding removed.
    462   /// \param ST the original store, that is the basis for the new store.
    463   /// \param L the location whose binding should be removed.
    464   StoreRef killBinding(Store ST, Loc L) override;
    465 
    466   void incrementReferenceCount(Store store) override {
    467     getRegionBindings(store).manualRetain();
    468   }
    469 
    470   /// If the StoreManager supports it, decrement the reference count of
    471   /// the specified Store object.  If the reference count hits 0, the memory
    472   /// associated with the object is recycled.
    473   void decrementReferenceCount(Store store) override {
    474     getRegionBindings(store).manualRelease();
    475   }
    476 
    477   bool includedInBindings(Store store, const MemRegion *region) const override;
    478 
    479   /// \brief Return the value bound to specified location in a given state.
    480   ///
    481   /// The high level logic for this method is this:
    482   /// getBinding (L)
    483   ///   if L has binding
    484   ///     return L's binding
    485   ///   else if L is in killset
    486   ///     return unknown
    487   ///   else
    488   ///     if L is on stack or heap
    489   ///       return undefined
    490   ///     else
    491   ///       return symbolic
    492   SVal getBinding(Store S, Loc L, QualType T) override {
    493     return getBinding(getRegionBindings(S), L, T);
    494   }
    495 
    496   SVal getBinding(RegionBindingsConstRef B, Loc L, QualType T = QualType());
    497 
    498   SVal getBindingForElement(RegionBindingsConstRef B, const ElementRegion *R);
    499 
    500   SVal getBindingForField(RegionBindingsConstRef B, const FieldRegion *R);
    501 
    502   SVal getBindingForObjCIvar(RegionBindingsConstRef B, const ObjCIvarRegion *R);
    503 
    504   SVal getBindingForVar(RegionBindingsConstRef B, const VarRegion *R);
    505 
    506   SVal getBindingForLazySymbol(const TypedValueRegion *R);
    507 
    508   SVal getBindingForFieldOrElementCommon(RegionBindingsConstRef B,
    509                                          const TypedValueRegion *R,
    510                                          QualType Ty);
    511 
    512   SVal getLazyBinding(const SubRegion *LazyBindingRegion,
    513                       RegionBindingsRef LazyBinding);
    514 
    515   /// Get bindings for the values in a struct and return a CompoundVal, used
    516   /// when doing struct copy:
    517   /// struct s x, y;
    518   /// x = y;
    519   /// y's value is retrieved by this method.
    520   SVal getBindingForStruct(RegionBindingsConstRef B, const TypedValueRegion *R);
    521   SVal getBindingForArray(RegionBindingsConstRef B, const TypedValueRegion *R);
    522   NonLoc createLazyBinding(RegionBindingsConstRef B, const TypedValueRegion *R);
    523 
    524   /// Used to lazily generate derived symbols for bindings that are defined
    525   /// implicitly by default bindings in a super region.
    526   ///
    527   /// Note that callers may need to specially handle LazyCompoundVals, which
    528   /// are returned as is in case the caller needs to treat them differently.
    529   Optional<SVal> getBindingForDerivedDefaultValue(RegionBindingsConstRef B,
    530                                                   const MemRegion *superR,
    531                                                   const TypedValueRegion *R,
    532                                                   QualType Ty);
    533 
    534   /// Get the state and region whose binding this region \p R corresponds to.
    535   ///
    536   /// If there is no lazy binding for \p R, the returned value will have a null
    537   /// \c second. Note that a null pointer can represents a valid Store.
    538   std::pair<Store, const SubRegion *>
    539   findLazyBinding(RegionBindingsConstRef B, const SubRegion *R,
    540                   const SubRegion *originalRegion);
    541 
    542   /// Returns the cached set of interesting SVals contained within a lazy
    543   /// binding.
    544   ///
    545   /// The precise value of "interesting" is determined for the purposes of
    546   /// RegionStore's internal analysis. It must always contain all regions and
    547   /// symbols, but may omit constants and other kinds of SVal.
    548   const SValListTy &getInterestingValues(nonloc::LazyCompoundVal LCV);
    549 
    550   //===------------------------------------------------------------------===//
    551   // State pruning.
    552   //===------------------------------------------------------------------===//
    553 
    554   /// removeDeadBindings - Scans the RegionStore of 'state' for dead values.
    555   ///  It returns a new Store with these values removed.
    556   StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx,
    557                               SymbolReaper& SymReaper) override;
    558 
    559   //===------------------------------------------------------------------===//
    560   // Region "extents".
    561   //===------------------------------------------------------------------===//
    562 
    563   // FIXME: This method will soon be eliminated; see the note in Store.h.
    564   DefinedOrUnknownSVal getSizeInElements(ProgramStateRef state,
    565                                          const MemRegion* R,
    566                                          QualType EleTy) override;
    567 
    568   //===------------------------------------------------------------------===//
    569   // Utility methods.
    570   //===------------------------------------------------------------------===//
    571 
    572   RegionBindingsRef getRegionBindings(Store store) const {
    573     return RegionBindingsRef(CBFactory,
    574                              static_cast<const RegionBindings::TreeTy*>(store),
    575                              RBFactory.getTreeFactory());
    576   }
    577 
    578   void print(Store store, raw_ostream &Out, const char* nl,
    579              const char *sep) override;
    580 
    581   void iterBindings(Store store, BindingsHandler& f) override {
    582     RegionBindingsRef B = getRegionBindings(store);
    583     for (RegionBindingsRef::iterator I = B.begin(), E = B.end(); I != E; ++I) {
    584       const ClusterBindings &Cluster = I.getData();
    585       for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
    586            CI != CE; ++CI) {
    587         const BindingKey &K = CI.getKey();
    588         if (!K.isDirect())
    589           continue;
    590         if (const SubRegion *R = dyn_cast<SubRegion>(K.getRegion())) {
    591           // FIXME: Possibly incorporate the offset?
    592           if (!f.HandleBinding(*this, store, R, CI.getData()))
    593             return;
    594         }
    595       }
    596     }
    597   }
    598 };
    599 
    600 } // end anonymous namespace
    601 
    602 //===----------------------------------------------------------------------===//
    603 // RegionStore creation.
    604 //===----------------------------------------------------------------------===//
    605 
    606 std::unique_ptr<StoreManager>
    607 ento::CreateRegionStoreManager(ProgramStateManager &StMgr) {
    608   RegionStoreFeatures F = maximal_features_tag();
    609   return llvm::make_unique<RegionStoreManager>(StMgr, F);
    610 }
    611 
    612 std::unique_ptr<StoreManager>
    613 ento::CreateFieldsOnlyRegionStoreManager(ProgramStateManager &StMgr) {
    614   RegionStoreFeatures F = minimal_features_tag();
    615   F.enableFields(true);
    616   return llvm::make_unique<RegionStoreManager>(StMgr, F);
    617 }
    618 
    619 
    620 //===----------------------------------------------------------------------===//
    621 // Region Cluster analysis.
    622 //===----------------------------------------------------------------------===//
    623 
    624 namespace {
    625 /// Used to determine which global regions are automatically included in the
    626 /// initial worklist of a ClusterAnalysis.
    627 enum GlobalsFilterKind {
    628   /// Don't include any global regions.
    629   GFK_None,
    630   /// Only include system globals.
    631   GFK_SystemOnly,
    632   /// Include all global regions.
    633   GFK_All
    634 };
    635 
    636 template <typename DERIVED>
    637 class ClusterAnalysis  {
    638 protected:
    639   typedef llvm::DenseMap<const MemRegion *, const ClusterBindings *> ClusterMap;
    640   typedef const MemRegion * WorkListElement;
    641   typedef SmallVector<WorkListElement, 10> WorkList;
    642 
    643   llvm::SmallPtrSet<const ClusterBindings *, 16> Visited;
    644 
    645   WorkList WL;
    646 
    647   RegionStoreManager &RM;
    648   ASTContext &Ctx;
    649   SValBuilder &svalBuilder;
    650 
    651   RegionBindingsRef B;
    652 
    653 
    654 protected:
    655   const ClusterBindings *getCluster(const MemRegion *R) {
    656     return B.lookup(R);
    657   }
    658 
    659   /// Returns true if all clusters in the given memspace should be initially
    660   /// included in the cluster analysis. Subclasses may provide their
    661   /// own implementation.
    662   bool includeEntireMemorySpace(const MemRegion *Base) {
    663     return false;
    664   }
    665 
    666 public:
    667   ClusterAnalysis(RegionStoreManager &rm, ProgramStateManager &StateMgr,
    668                   RegionBindingsRef b )
    669     : RM(rm), Ctx(StateMgr.getContext()),
    670       svalBuilder(StateMgr.getSValBuilder()),
    671       B(b) {}
    672 
    673   RegionBindingsRef getRegionBindings() const { return B; }
    674 
    675   bool isVisited(const MemRegion *R) {
    676     return Visited.count(getCluster(R));
    677   }
    678 
    679   void GenerateClusters() {
    680     // Scan the entire set of bindings and record the region clusters.
    681     for (RegionBindingsRef::iterator RI = B.begin(), RE = B.end();
    682          RI != RE; ++RI){
    683       const MemRegion *Base = RI.getKey();
    684 
    685       const ClusterBindings &Cluster = RI.getData();
    686       assert(!Cluster.isEmpty() && "Empty clusters should be removed");
    687       static_cast<DERIVED*>(this)->VisitAddedToCluster(Base, Cluster);
    688 
    689       // If the base's memspace should be entirely invalidated, add the cluster
    690       // to the workspace up front.
    691       if (static_cast<DERIVED*>(this)->includeEntireMemorySpace(Base))
    692         AddToWorkList(WorkListElement(Base), &Cluster);
    693     }
    694   }
    695 
    696   bool AddToWorkList(WorkListElement E, const ClusterBindings *C) {
    697     if (C && !Visited.insert(C).second)
    698       return false;
    699     WL.push_back(E);
    700     return true;
    701   }
    702 
    703   bool AddToWorkList(const MemRegion *R) {
    704     return static_cast<DERIVED*>(this)->AddToWorkList(R);
    705   }
    706 
    707   void RunWorkList() {
    708     while (!WL.empty()) {
    709       WorkListElement E = WL.pop_back_val();
    710       const MemRegion *BaseR = E;
    711 
    712       static_cast<DERIVED*>(this)->VisitCluster(BaseR, getCluster(BaseR));
    713     }
    714   }
    715 
    716   void VisitAddedToCluster(const MemRegion *baseR, const ClusterBindings &C) {}
    717   void VisitCluster(const MemRegion *baseR, const ClusterBindings *C) {}
    718 
    719   void VisitCluster(const MemRegion *BaseR, const ClusterBindings *C,
    720                     bool Flag) {
    721     static_cast<DERIVED*>(this)->VisitCluster(BaseR, C);
    722   }
    723 };
    724 }
    725 
    726 //===----------------------------------------------------------------------===//
    727 // Binding invalidation.
    728 //===----------------------------------------------------------------------===//
    729 
    730 bool RegionStoreManager::scanReachableSymbols(Store S, const MemRegion *R,
    731                                               ScanReachableSymbols &Callbacks) {
    732   assert(R == R->getBaseRegion() && "Should only be called for base regions");
    733   RegionBindingsRef B = getRegionBindings(S);
    734   const ClusterBindings *Cluster = B.lookup(R);
    735 
    736   if (!Cluster)
    737     return true;
    738 
    739   for (ClusterBindings::iterator RI = Cluster->begin(), RE = Cluster->end();
    740        RI != RE; ++RI) {
    741     if (!Callbacks.scan(RI.getData()))
    742       return false;
    743   }
    744 
    745   return true;
    746 }
    747 
    748 static inline bool isUnionField(const FieldRegion *FR) {
    749   return FR->getDecl()->getParent()->isUnion();
    750 }
    751 
    752 typedef SmallVector<const FieldDecl *, 8> FieldVector;
    753 
    754 static void getSymbolicOffsetFields(BindingKey K, FieldVector &Fields) {
    755   assert(K.hasSymbolicOffset() && "Not implemented for concrete offset keys");
    756 
    757   const MemRegion *Base = K.getConcreteOffsetRegion();
    758   const MemRegion *R = K.getRegion();
    759 
    760   while (R != Base) {
    761     if (const FieldRegion *FR = dyn_cast<FieldRegion>(R))
    762       if (!isUnionField(FR))
    763         Fields.push_back(FR->getDecl());
    764 
    765     R = cast<SubRegion>(R)->getSuperRegion();
    766   }
    767 }
    768 
    769 static bool isCompatibleWithFields(BindingKey K, const FieldVector &Fields) {
    770   assert(K.hasSymbolicOffset() && "Not implemented for concrete offset keys");
    771 
    772   if (Fields.empty())
    773     return true;
    774 
    775   FieldVector FieldsInBindingKey;
    776   getSymbolicOffsetFields(K, FieldsInBindingKey);
    777 
    778   ptrdiff_t Delta = FieldsInBindingKey.size() - Fields.size();
    779   if (Delta >= 0)
    780     return std::equal(FieldsInBindingKey.begin() + Delta,
    781                       FieldsInBindingKey.end(),
    782                       Fields.begin());
    783   else
    784     return std::equal(FieldsInBindingKey.begin(), FieldsInBindingKey.end(),
    785                       Fields.begin() - Delta);
    786 }
    787 
    788 /// Collects all bindings in \p Cluster that may refer to bindings within
    789 /// \p Top.
    790 ///
    791 /// Each binding is a pair whose \c first is the key (a BindingKey) and whose
    792 /// \c second is the value (an SVal).
    793 ///
    794 /// The \p IncludeAllDefaultBindings parameter specifies whether to include
    795 /// default bindings that may extend beyond \p Top itself, e.g. if \p Top is
    796 /// an aggregate within a larger aggregate with a default binding.
    797 static void
    798 collectSubRegionBindings(SmallVectorImpl<BindingPair> &Bindings,
    799                          SValBuilder &SVB, const ClusterBindings &Cluster,
    800                          const SubRegion *Top, BindingKey TopKey,
    801                          bool IncludeAllDefaultBindings) {
    802   FieldVector FieldsInSymbolicSubregions;
    803   if (TopKey.hasSymbolicOffset()) {
    804     getSymbolicOffsetFields(TopKey, FieldsInSymbolicSubregions);
    805     Top = cast<SubRegion>(TopKey.getConcreteOffsetRegion());
    806     TopKey = BindingKey::Make(Top, BindingKey::Default);
    807   }
    808 
    809   // Find the length (in bits) of the region being invalidated.
    810   uint64_t Length = UINT64_MAX;
    811   SVal Extent = Top->getExtent(SVB);
    812   if (Optional<nonloc::ConcreteInt> ExtentCI =
    813           Extent.getAs<nonloc::ConcreteInt>()) {
    814     const llvm::APSInt &ExtentInt = ExtentCI->getValue();
    815     assert(ExtentInt.isNonNegative() || ExtentInt.isUnsigned());
    816     // Extents are in bytes but region offsets are in bits. Be careful!
    817     Length = ExtentInt.getLimitedValue() * SVB.getContext().getCharWidth();
    818   } else if (const FieldRegion *FR = dyn_cast<FieldRegion>(Top)) {
    819     if (FR->getDecl()->isBitField())
    820       Length = FR->getDecl()->getBitWidthValue(SVB.getContext());
    821   }
    822 
    823   for (ClusterBindings::iterator I = Cluster.begin(), E = Cluster.end();
    824        I != E; ++I) {
    825     BindingKey NextKey = I.getKey();
    826     if (NextKey.getRegion() == TopKey.getRegion()) {
    827       // FIXME: This doesn't catch the case where we're really invalidating a
    828       // region with a symbolic offset. Example:
    829       //      R: points[i].y
    830       //   Next: points[0].x
    831 
    832       if (NextKey.getOffset() > TopKey.getOffset() &&
    833           NextKey.getOffset() - TopKey.getOffset() < Length) {
    834         // Case 1: The next binding is inside the region we're invalidating.
    835         // Include it.
    836         Bindings.push_back(*I);
    837 
    838       } else if (NextKey.getOffset() == TopKey.getOffset()) {
    839         // Case 2: The next binding is at the same offset as the region we're
    840         // invalidating. In this case, we need to leave default bindings alone,
    841         // since they may be providing a default value for a regions beyond what
    842         // we're invalidating.
    843         // FIXME: This is probably incorrect; consider invalidating an outer
    844         // struct whose first field is bound to a LazyCompoundVal.
    845         if (IncludeAllDefaultBindings || NextKey.isDirect())
    846           Bindings.push_back(*I);
    847       }
    848 
    849     } else if (NextKey.hasSymbolicOffset()) {
    850       const MemRegion *Base = NextKey.getConcreteOffsetRegion();
    851       if (Top->isSubRegionOf(Base)) {
    852         // Case 3: The next key is symbolic and we just changed something within
    853         // its concrete region. We don't know if the binding is still valid, so
    854         // we'll be conservative and include it.
    855         if (IncludeAllDefaultBindings || NextKey.isDirect())
    856           if (isCompatibleWithFields(NextKey, FieldsInSymbolicSubregions))
    857             Bindings.push_back(*I);
    858       } else if (const SubRegion *BaseSR = dyn_cast<SubRegion>(Base)) {
    859         // Case 4: The next key is symbolic, but we changed a known
    860         // super-region. In this case the binding is certainly included.
    861         if (Top == Base || BaseSR->isSubRegionOf(Top))
    862           if (isCompatibleWithFields(NextKey, FieldsInSymbolicSubregions))
    863             Bindings.push_back(*I);
    864       }
    865     }
    866   }
    867 }
    868 
    869 static void
    870 collectSubRegionBindings(SmallVectorImpl<BindingPair> &Bindings,
    871                          SValBuilder &SVB, const ClusterBindings &Cluster,
    872                          const SubRegion *Top, bool IncludeAllDefaultBindings) {
    873   collectSubRegionBindings(Bindings, SVB, Cluster, Top,
    874                            BindingKey::Make(Top, BindingKey::Default),
    875                            IncludeAllDefaultBindings);
    876 }
    877 
    878 RegionBindingsRef
    879 RegionStoreManager::removeSubRegionBindings(RegionBindingsConstRef B,
    880                                             const SubRegion *Top) {
    881   BindingKey TopKey = BindingKey::Make(Top, BindingKey::Default);
    882   const MemRegion *ClusterHead = TopKey.getBaseRegion();
    883 
    884   if (Top == ClusterHead) {
    885     // We can remove an entire cluster's bindings all in one go.
    886     return B.remove(Top);
    887   }
    888 
    889   const ClusterBindings *Cluster = B.lookup(ClusterHead);
    890   if (!Cluster) {
    891     // If we're invalidating a region with a symbolic offset, we need to make
    892     // sure we don't treat the base region as uninitialized anymore.
    893     if (TopKey.hasSymbolicOffset()) {
    894       const SubRegion *Concrete = TopKey.getConcreteOffsetRegion();
    895       return B.addBinding(Concrete, BindingKey::Default, UnknownVal());
    896     }
    897     return B;
    898   }
    899 
    900   SmallVector<BindingPair, 32> Bindings;
    901   collectSubRegionBindings(Bindings, svalBuilder, *Cluster, Top, TopKey,
    902                            /*IncludeAllDefaultBindings=*/false);
    903 
    904   ClusterBindingsRef Result(*Cluster, CBFactory);
    905   for (SmallVectorImpl<BindingPair>::const_iterator I = Bindings.begin(),
    906                                                     E = Bindings.end();
    907        I != E; ++I)
    908     Result = Result.remove(I->first);
    909 
    910   // If we're invalidating a region with a symbolic offset, we need to make sure
    911   // we don't treat the base region as uninitialized anymore.
    912   // FIXME: This isn't very precise; see the example in
    913   // collectSubRegionBindings.
    914   if (TopKey.hasSymbolicOffset()) {
    915     const SubRegion *Concrete = TopKey.getConcreteOffsetRegion();
    916     Result = Result.add(BindingKey::Make(Concrete, BindingKey::Default),
    917                         UnknownVal());
    918   }
    919 
    920   if (Result.isEmpty())
    921     return B.remove(ClusterHead);
    922   return B.add(ClusterHead, Result.asImmutableMap());
    923 }
    924 
    925 namespace {
    926 class invalidateRegionsWorker : public ClusterAnalysis<invalidateRegionsWorker>
    927 {
    928   const Expr *Ex;
    929   unsigned Count;
    930   const LocationContext *LCtx;
    931   InvalidatedSymbols &IS;
    932   RegionAndSymbolInvalidationTraits &ITraits;
    933   StoreManager::InvalidatedRegions *Regions;
    934   GlobalsFilterKind GlobalsFilter;
    935 public:
    936   invalidateRegionsWorker(RegionStoreManager &rm,
    937                           ProgramStateManager &stateMgr,
    938                           RegionBindingsRef b,
    939                           const Expr *ex, unsigned count,
    940                           const LocationContext *lctx,
    941                           InvalidatedSymbols &is,
    942                           RegionAndSymbolInvalidationTraits &ITraitsIn,
    943                           StoreManager::InvalidatedRegions *r,
    944                           GlobalsFilterKind GFK)
    945      : ClusterAnalysis<invalidateRegionsWorker>(rm, stateMgr, b),
    946        Ex(ex), Count(count), LCtx(lctx), IS(is), ITraits(ITraitsIn), Regions(r),
    947        GlobalsFilter(GFK) {}
    948 
    949   void VisitCluster(const MemRegion *baseR, const ClusterBindings *C);
    950   void VisitBinding(SVal V);
    951 
    952   using ClusterAnalysis::AddToWorkList;
    953 
    954   bool AddToWorkList(const MemRegion *R);
    955 
    956   /// Returns true if all clusters in the memory space for \p Base should be
    957   /// be invalidated.
    958   bool includeEntireMemorySpace(const MemRegion *Base);
    959 
    960   /// Returns true if the memory space of the given region is one of the global
    961   /// regions specially included at the start of invalidation.
    962   bool isInitiallyIncludedGlobalRegion(const MemRegion *R);
    963 };
    964 }
    965 
    966 bool invalidateRegionsWorker::AddToWorkList(const MemRegion *R) {
    967   bool doNotInvalidateSuperRegion = ITraits.hasTrait(
    968       R, RegionAndSymbolInvalidationTraits::TK_DoNotInvalidateSuperRegion);
    969   const MemRegion *BaseR = doNotInvalidateSuperRegion ? R : R->getBaseRegion();
    970   return AddToWorkList(WorkListElement(BaseR), getCluster(BaseR));
    971 }
    972 
    973 void invalidateRegionsWorker::VisitBinding(SVal V) {
    974   // A symbol?  Mark it touched by the invalidation.
    975   if (SymbolRef Sym = V.getAsSymbol())
    976     IS.insert(Sym);
    977 
    978   if (const MemRegion *R = V.getAsRegion()) {
    979     AddToWorkList(R);
    980     return;
    981   }
    982 
    983   // Is it a LazyCompoundVal?  All references get invalidated as well.
    984   if (Optional<nonloc::LazyCompoundVal> LCS =
    985           V.getAs<nonloc::LazyCompoundVal>()) {
    986 
    987     const RegionStoreManager::SValListTy &Vals = RM.getInterestingValues(*LCS);
    988 
    989     for (RegionStoreManager::SValListTy::const_iterator I = Vals.begin(),
    990                                                         E = Vals.end();
    991          I != E; ++I)
    992       VisitBinding(*I);
    993 
    994     return;
    995   }
    996 }
    997 
    998 void invalidateRegionsWorker::VisitCluster(const MemRegion *baseR,
    999                                            const ClusterBindings *C) {
   1000 
   1001   bool PreserveRegionsContents =
   1002       ITraits.hasTrait(baseR,
   1003                        RegionAndSymbolInvalidationTraits::TK_PreserveContents);
   1004 
   1005   if (C) {
   1006     for (ClusterBindings::iterator I = C->begin(), E = C->end(); I != E; ++I)
   1007       VisitBinding(I.getData());
   1008 
   1009     // Invalidate regions contents.
   1010     if (!PreserveRegionsContents)
   1011       B = B.remove(baseR);
   1012   }
   1013 
   1014   // BlockDataRegion?  If so, invalidate captured variables that are passed
   1015   // by reference.
   1016   if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(baseR)) {
   1017     for (BlockDataRegion::referenced_vars_iterator
   1018          BI = BR->referenced_vars_begin(), BE = BR->referenced_vars_end() ;
   1019          BI != BE; ++BI) {
   1020       const VarRegion *VR = BI.getCapturedRegion();
   1021       const VarDecl *VD = VR->getDecl();
   1022       if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage()) {
   1023         AddToWorkList(VR);
   1024       }
   1025       else if (Loc::isLocType(VR->getValueType())) {
   1026         // Map the current bindings to a Store to retrieve the value
   1027         // of the binding.  If that binding itself is a region, we should
   1028         // invalidate that region.  This is because a block may capture
   1029         // a pointer value, but the thing pointed by that pointer may
   1030         // get invalidated.
   1031         SVal V = RM.getBinding(B, loc::MemRegionVal(VR));
   1032         if (Optional<Loc> L = V.getAs<Loc>()) {
   1033           if (const MemRegion *LR = L->getAsRegion())
   1034             AddToWorkList(LR);
   1035         }
   1036       }
   1037     }
   1038     return;
   1039   }
   1040 
   1041   // Symbolic region?
   1042   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(baseR))
   1043     IS.insert(SR->getSymbol());
   1044 
   1045   // Nothing else should be done in the case when we preserve regions context.
   1046   if (PreserveRegionsContents)
   1047     return;
   1048 
   1049   // Otherwise, we have a normal data region. Record that we touched the region.
   1050   if (Regions)
   1051     Regions->push_back(baseR);
   1052 
   1053   if (isa<AllocaRegion>(baseR) || isa<SymbolicRegion>(baseR)) {
   1054     // Invalidate the region by setting its default value to
   1055     // conjured symbol. The type of the symbol is irrelevant.
   1056     DefinedOrUnknownSVal V =
   1057       svalBuilder.conjureSymbolVal(baseR, Ex, LCtx, Ctx.IntTy, Count);
   1058     B = B.addBinding(baseR, BindingKey::Default, V);
   1059     return;
   1060   }
   1061 
   1062   if (!baseR->isBoundable())
   1063     return;
   1064 
   1065   const TypedValueRegion *TR = cast<TypedValueRegion>(baseR);
   1066   QualType T = TR->getValueType();
   1067 
   1068   if (isInitiallyIncludedGlobalRegion(baseR)) {
   1069     // If the region is a global and we are invalidating all globals,
   1070     // erasing the entry is good enough.  This causes all globals to be lazily
   1071     // symbolicated from the same base symbol.
   1072     return;
   1073   }
   1074 
   1075   if (T->isStructureOrClassType()) {
   1076     // Invalidate the region by setting its default value to
   1077     // conjured symbol. The type of the symbol is irrelevant.
   1078     DefinedOrUnknownSVal V = svalBuilder.conjureSymbolVal(baseR, Ex, LCtx,
   1079                                                           Ctx.IntTy, Count);
   1080     B = B.addBinding(baseR, BindingKey::Default, V);
   1081     return;
   1082   }
   1083 
   1084   if (const ArrayType *AT = Ctx.getAsArrayType(T)) {
   1085     bool doNotInvalidateSuperRegion = ITraits.hasTrait(
   1086         baseR,
   1087         RegionAndSymbolInvalidationTraits::TK_DoNotInvalidateSuperRegion);
   1088 
   1089     if (doNotInvalidateSuperRegion) {
   1090       // We are not doing blank invalidation of the whole array region so we
   1091       // have to manually invalidate each elements.
   1092       Optional<uint64_t> NumElements;
   1093 
   1094       // Compute lower and upper offsets for region within array.
   1095       if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(AT))
   1096         NumElements = CAT->getSize().getZExtValue();
   1097       if (!NumElements) // We are not dealing with a constant size array
   1098         goto conjure_default;
   1099       QualType ElementTy = AT->getElementType();
   1100       uint64_t ElemSize = Ctx.getTypeSize(ElementTy);
   1101       const RegionOffset &RO = baseR->getAsOffset();
   1102       const MemRegion *SuperR = baseR->getBaseRegion();
   1103       if (RO.hasSymbolicOffset()) {
   1104         // If base region has a symbolic offset,
   1105         // we revert to invalidating the super region.
   1106         if (SuperR)
   1107           AddToWorkList(SuperR);
   1108         goto conjure_default;
   1109       }
   1110 
   1111       uint64_t LowerOffset = RO.getOffset();
   1112       uint64_t UpperOffset = LowerOffset + *NumElements * ElemSize;
   1113       bool UpperOverflow = UpperOffset < LowerOffset;
   1114 
   1115       // Invalidate regions which are within array boundaries,
   1116       // or have a symbolic offset.
   1117       if (!SuperR)
   1118         goto conjure_default;
   1119 
   1120       const ClusterBindings *C = B.lookup(SuperR);
   1121       if (!C)
   1122         goto conjure_default;
   1123 
   1124       for (ClusterBindings::iterator I = C->begin(), E = C->end(); I != E;
   1125            ++I) {
   1126         const BindingKey &BK = I.getKey();
   1127         Optional<uint64_t> ROffset =
   1128             BK.hasSymbolicOffset() ? Optional<uint64_t>() : BK.getOffset();
   1129 
   1130         // Check offset is not symbolic and within array's boundaries.
   1131         // Handles arrays of 0 elements and of 0-sized elements as well.
   1132         if (!ROffset ||
   1133             (ROffset &&
   1134              ((*ROffset >= LowerOffset && *ROffset < UpperOffset) ||
   1135               (UpperOverflow &&
   1136                (*ROffset >= LowerOffset || *ROffset < UpperOffset)) ||
   1137               (LowerOffset == UpperOffset && *ROffset == LowerOffset)))) {
   1138           B = B.removeBinding(I.getKey());
   1139           // Bound symbolic regions need to be invalidated for dead symbol
   1140           // detection.
   1141           SVal V = I.getData();
   1142           const MemRegion *R = V.getAsRegion();
   1143           if (R && isa<SymbolicRegion>(R))
   1144             VisitBinding(V);
   1145         }
   1146       }
   1147     }
   1148   conjure_default:
   1149       // Set the default value of the array to conjured symbol.
   1150     DefinedOrUnknownSVal V =
   1151     svalBuilder.conjureSymbolVal(baseR, Ex, LCtx,
   1152                                      AT->getElementType(), Count);
   1153     B = B.addBinding(baseR, BindingKey::Default, V);
   1154     return;
   1155   }
   1156 
   1157   DefinedOrUnknownSVal V = svalBuilder.conjureSymbolVal(baseR, Ex, LCtx,
   1158                                                         T,Count);
   1159   assert(SymbolManager::canSymbolicate(T) || V.isUnknown());
   1160   B = B.addBinding(baseR, BindingKey::Direct, V);
   1161 }
   1162 
   1163 bool invalidateRegionsWorker::isInitiallyIncludedGlobalRegion(
   1164     const MemRegion *R) {
   1165   switch (GlobalsFilter) {
   1166   case GFK_None:
   1167     return false;
   1168   case GFK_SystemOnly:
   1169     return isa<GlobalSystemSpaceRegion>(R->getMemorySpace());
   1170   case GFK_All:
   1171     return isa<NonStaticGlobalSpaceRegion>(R->getMemorySpace());
   1172   }
   1173 
   1174   llvm_unreachable("unknown globals filter");
   1175 }
   1176 
   1177 bool invalidateRegionsWorker::includeEntireMemorySpace(const MemRegion *Base) {
   1178   if (isInitiallyIncludedGlobalRegion(Base))
   1179     return true;
   1180 
   1181   const MemSpaceRegion *MemSpace = Base->getMemorySpace();
   1182   return ITraits.hasTrait(MemSpace,
   1183                           RegionAndSymbolInvalidationTraits::TK_EntireMemSpace);
   1184 }
   1185 
   1186 RegionBindingsRef
   1187 RegionStoreManager::invalidateGlobalRegion(MemRegion::Kind K,
   1188                                            const Expr *Ex,
   1189                                            unsigned Count,
   1190                                            const LocationContext *LCtx,
   1191                                            RegionBindingsRef B,
   1192                                            InvalidatedRegions *Invalidated) {
   1193   // Bind the globals memory space to a new symbol that we will use to derive
   1194   // the bindings for all globals.
   1195   const GlobalsSpaceRegion *GS = MRMgr.getGlobalsRegion(K);
   1196   SVal V = svalBuilder.conjureSymbolVal(/* SymbolTag = */ (const void*) GS, Ex, LCtx,
   1197                                         /* type does not matter */ Ctx.IntTy,
   1198                                         Count);
   1199 
   1200   B = B.removeBinding(GS)
   1201        .addBinding(BindingKey::Make(GS, BindingKey::Default), V);
   1202 
   1203   // Even if there are no bindings in the global scope, we still need to
   1204   // record that we touched it.
   1205   if (Invalidated)
   1206     Invalidated->push_back(GS);
   1207 
   1208   return B;
   1209 }
   1210 
   1211 void RegionStoreManager::populateWorkList(invalidateRegionsWorker &W,
   1212                                           ArrayRef<SVal> Values,
   1213                                           InvalidatedRegions *TopLevelRegions) {
   1214   for (ArrayRef<SVal>::iterator I = Values.begin(),
   1215                                 E = Values.end(); I != E; ++I) {
   1216     SVal V = *I;
   1217     if (Optional<nonloc::LazyCompoundVal> LCS =
   1218         V.getAs<nonloc::LazyCompoundVal>()) {
   1219 
   1220       const SValListTy &Vals = getInterestingValues(*LCS);
   1221 
   1222       for (SValListTy::const_iterator I = Vals.begin(),
   1223                                       E = Vals.end(); I != E; ++I) {
   1224         // Note: the last argument is false here because these are
   1225         // non-top-level regions.
   1226         if (const MemRegion *R = (*I).getAsRegion())
   1227           W.AddToWorkList(R);
   1228       }
   1229       continue;
   1230     }
   1231 
   1232     if (const MemRegion *R = V.getAsRegion()) {
   1233       if (TopLevelRegions)
   1234         TopLevelRegions->push_back(R);
   1235       W.AddToWorkList(R);
   1236       continue;
   1237     }
   1238   }
   1239 }
   1240 
   1241 StoreRef
   1242 RegionStoreManager::invalidateRegions(Store store,
   1243                                      ArrayRef<SVal> Values,
   1244                                      const Expr *Ex, unsigned Count,
   1245                                      const LocationContext *LCtx,
   1246                                      const CallEvent *Call,
   1247                                      InvalidatedSymbols &IS,
   1248                                      RegionAndSymbolInvalidationTraits &ITraits,
   1249                                      InvalidatedRegions *TopLevelRegions,
   1250                                      InvalidatedRegions *Invalidated) {
   1251   GlobalsFilterKind GlobalsFilter;
   1252   if (Call) {
   1253     if (Call->isInSystemHeader())
   1254       GlobalsFilter = GFK_SystemOnly;
   1255     else
   1256       GlobalsFilter = GFK_All;
   1257   } else {
   1258     GlobalsFilter = GFK_None;
   1259   }
   1260 
   1261   RegionBindingsRef B = getRegionBindings(store);
   1262   invalidateRegionsWorker W(*this, StateMgr, B, Ex, Count, LCtx, IS, ITraits,
   1263                             Invalidated, GlobalsFilter);
   1264 
   1265   // Scan the bindings and generate the clusters.
   1266   W.GenerateClusters();
   1267 
   1268   // Add the regions to the worklist.
   1269   populateWorkList(W, Values, TopLevelRegions);
   1270 
   1271   W.RunWorkList();
   1272 
   1273   // Return the new bindings.
   1274   B = W.getRegionBindings();
   1275 
   1276   // For calls, determine which global regions should be invalidated and
   1277   // invalidate them. (Note that function-static and immutable globals are never
   1278   // invalidated by this.)
   1279   // TODO: This could possibly be more precise with modules.
   1280   switch (GlobalsFilter) {
   1281   case GFK_All:
   1282     B = invalidateGlobalRegion(MemRegion::GlobalInternalSpaceRegionKind,
   1283                                Ex, Count, LCtx, B, Invalidated);
   1284     // FALLTHROUGH
   1285   case GFK_SystemOnly:
   1286     B = invalidateGlobalRegion(MemRegion::GlobalSystemSpaceRegionKind,
   1287                                Ex, Count, LCtx, B, Invalidated);
   1288     // FALLTHROUGH
   1289   case GFK_None:
   1290     break;
   1291   }
   1292 
   1293   return StoreRef(B.asStore(), *this);
   1294 }
   1295 
   1296 //===----------------------------------------------------------------------===//
   1297 // Extents for regions.
   1298 //===----------------------------------------------------------------------===//
   1299 
   1300 DefinedOrUnknownSVal
   1301 RegionStoreManager::getSizeInElements(ProgramStateRef state,
   1302                                       const MemRegion *R,
   1303                                       QualType EleTy) {
   1304   SVal Size = cast<SubRegion>(R)->getExtent(svalBuilder);
   1305   const llvm::APSInt *SizeInt = svalBuilder.getKnownValue(state, Size);
   1306   if (!SizeInt)
   1307     return UnknownVal();
   1308 
   1309   CharUnits RegionSize = CharUnits::fromQuantity(SizeInt->getSExtValue());
   1310 
   1311   if (Ctx.getAsVariableArrayType(EleTy)) {
   1312     // FIXME: We need to track extra state to properly record the size
   1313     // of VLAs.  Returning UnknownVal here, however, is a stop-gap so that
   1314     // we don't have a divide-by-zero below.
   1315     return UnknownVal();
   1316   }
   1317 
   1318   CharUnits EleSize = Ctx.getTypeSizeInChars(EleTy);
   1319 
   1320   // If a variable is reinterpreted as a type that doesn't fit into a larger
   1321   // type evenly, round it down.
   1322   // This is a signed value, since it's used in arithmetic with signed indices.
   1323   return svalBuilder.makeIntVal(RegionSize / EleSize, false);
   1324 }
   1325 
   1326 //===----------------------------------------------------------------------===//
   1327 // Location and region casting.
   1328 //===----------------------------------------------------------------------===//
   1329 
   1330 /// ArrayToPointer - Emulates the "decay" of an array to a pointer
   1331 ///  type.  'Array' represents the lvalue of the array being decayed
   1332 ///  to a pointer, and the returned SVal represents the decayed
   1333 ///  version of that lvalue (i.e., a pointer to the first element of
   1334 ///  the array).  This is called by ExprEngine when evaluating casts
   1335 ///  from arrays to pointers.
   1336 SVal RegionStoreManager::ArrayToPointer(Loc Array, QualType T) {
   1337   if (!Array.getAs<loc::MemRegionVal>())
   1338     return UnknownVal();
   1339 
   1340   const MemRegion* R = Array.castAs<loc::MemRegionVal>().getRegion();
   1341   NonLoc ZeroIdx = svalBuilder.makeZeroArrayIndex();
   1342   return loc::MemRegionVal(MRMgr.getElementRegion(T, ZeroIdx, R, Ctx));
   1343 }
   1344 
   1345 //===----------------------------------------------------------------------===//
   1346 // Loading values from regions.
   1347 //===----------------------------------------------------------------------===//
   1348 
   1349 SVal RegionStoreManager::getBinding(RegionBindingsConstRef B, Loc L, QualType T) {
   1350   assert(!L.getAs<UnknownVal>() && "location unknown");
   1351   assert(!L.getAs<UndefinedVal>() && "location undefined");
   1352 
   1353   // For access to concrete addresses, return UnknownVal.  Checks
   1354   // for null dereferences (and similar errors) are done by checkers, not
   1355   // the Store.
   1356   // FIXME: We can consider lazily symbolicating such memory, but we really
   1357   // should defer this when we can reason easily about symbolicating arrays
   1358   // of bytes.
   1359   if (L.getAs<loc::ConcreteInt>()) {
   1360     return UnknownVal();
   1361   }
   1362   if (!L.getAs<loc::MemRegionVal>()) {
   1363     return UnknownVal();
   1364   }
   1365 
   1366   const MemRegion *MR = L.castAs<loc::MemRegionVal>().getRegion();
   1367 
   1368   if (isa<BlockDataRegion>(MR)) {
   1369     return UnknownVal();
   1370   }
   1371 
   1372   if (isa<AllocaRegion>(MR) ||
   1373       isa<SymbolicRegion>(MR) ||
   1374       isa<CodeTextRegion>(MR)) {
   1375     if (T.isNull()) {
   1376       if (const TypedRegion *TR = dyn_cast<TypedRegion>(MR))
   1377         T = TR->getLocationType();
   1378       else {
   1379         const SymbolicRegion *SR = cast<SymbolicRegion>(MR);
   1380         T = SR->getSymbol()->getType();
   1381       }
   1382     }
   1383     MR = GetElementZeroRegion(MR, T);
   1384   }
   1385 
   1386   // FIXME: Perhaps this method should just take a 'const MemRegion*' argument
   1387   //  instead of 'Loc', and have the other Loc cases handled at a higher level.
   1388   const TypedValueRegion *R = cast<TypedValueRegion>(MR);
   1389   QualType RTy = R->getValueType();
   1390 
   1391   // FIXME: we do not yet model the parts of a complex type, so treat the
   1392   // whole thing as "unknown".
   1393   if (RTy->isAnyComplexType())
   1394     return UnknownVal();
   1395 
   1396   // FIXME: We should eventually handle funny addressing.  e.g.:
   1397   //
   1398   //   int x = ...;
   1399   //   int *p = &x;
   1400   //   char *q = (char*) p;
   1401   //   char c = *q;  // returns the first byte of 'x'.
   1402   //
   1403   // Such funny addressing will occur due to layering of regions.
   1404   if (RTy->isStructureOrClassType())
   1405     return getBindingForStruct(B, R);
   1406 
   1407   // FIXME: Handle unions.
   1408   if (RTy->isUnionType())
   1409     return createLazyBinding(B, R);
   1410 
   1411   if (RTy->isArrayType()) {
   1412     if (RTy->isConstantArrayType())
   1413       return getBindingForArray(B, R);
   1414     else
   1415       return UnknownVal();
   1416   }
   1417 
   1418   // FIXME: handle Vector types.
   1419   if (RTy->isVectorType())
   1420     return UnknownVal();
   1421 
   1422   if (const FieldRegion* FR = dyn_cast<FieldRegion>(R))
   1423     return CastRetrievedVal(getBindingForField(B, FR), FR, T, false);
   1424 
   1425   if (const ElementRegion* ER = dyn_cast<ElementRegion>(R)) {
   1426     // FIXME: Here we actually perform an implicit conversion from the loaded
   1427     // value to the element type.  Eventually we want to compose these values
   1428     // more intelligently.  For example, an 'element' can encompass multiple
   1429     // bound regions (e.g., several bound bytes), or could be a subset of
   1430     // a larger value.
   1431     return CastRetrievedVal(getBindingForElement(B, ER), ER, T, false);
   1432   }
   1433 
   1434   if (const ObjCIvarRegion *IVR = dyn_cast<ObjCIvarRegion>(R)) {
   1435     // FIXME: Here we actually perform an implicit conversion from the loaded
   1436     // value to the ivar type.  What we should model is stores to ivars
   1437     // that blow past the extent of the ivar.  If the address of the ivar is
   1438     // reinterpretted, it is possible we stored a different value that could
   1439     // fit within the ivar.  Either we need to cast these when storing them
   1440     // or reinterpret them lazily (as we do here).
   1441     return CastRetrievedVal(getBindingForObjCIvar(B, IVR), IVR, T, false);
   1442   }
   1443 
   1444   if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
   1445     // FIXME: Here we actually perform an implicit conversion from the loaded
   1446     // value to the variable type.  What we should model is stores to variables
   1447     // that blow past the extent of the variable.  If the address of the
   1448     // variable is reinterpretted, it is possible we stored a different value
   1449     // that could fit within the variable.  Either we need to cast these when
   1450     // storing them or reinterpret them lazily (as we do here).
   1451     return CastRetrievedVal(getBindingForVar(B, VR), VR, T, false);
   1452   }
   1453 
   1454   const SVal *V = B.lookup(R, BindingKey::Direct);
   1455 
   1456   // Check if the region has a binding.
   1457   if (V)
   1458     return *V;
   1459 
   1460   // The location does not have a bound value.  This means that it has
   1461   // the value it had upon its creation and/or entry to the analyzed
   1462   // function/method.  These are either symbolic values or 'undefined'.
   1463   if (R->hasStackNonParametersStorage()) {
   1464     // All stack variables are considered to have undefined values
   1465     // upon creation.  All heap allocated blocks are considered to
   1466     // have undefined values as well unless they are explicitly bound
   1467     // to specific values.
   1468     return UndefinedVal();
   1469   }
   1470 
   1471   // All other values are symbolic.
   1472   return svalBuilder.getRegionValueSymbolVal(R);
   1473 }
   1474 
   1475 static QualType getUnderlyingType(const SubRegion *R) {
   1476   QualType RegionTy;
   1477   if (const TypedValueRegion *TVR = dyn_cast<TypedValueRegion>(R))
   1478     RegionTy = TVR->getValueType();
   1479 
   1480   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
   1481     RegionTy = SR->getSymbol()->getType();
   1482 
   1483   return RegionTy;
   1484 }
   1485 
   1486 /// Checks to see if store \p B has a lazy binding for region \p R.
   1487 ///
   1488 /// If \p AllowSubregionBindings is \c false, a lazy binding will be rejected
   1489 /// if there are additional bindings within \p R.
   1490 ///
   1491 /// Note that unlike RegionStoreManager::findLazyBinding, this will not search
   1492 /// for lazy bindings for super-regions of \p R.
   1493 static Optional<nonloc::LazyCompoundVal>
   1494 getExistingLazyBinding(SValBuilder &SVB, RegionBindingsConstRef B,
   1495                        const SubRegion *R, bool AllowSubregionBindings) {
   1496   Optional<SVal> V = B.getDefaultBinding(R);
   1497   if (!V)
   1498     return None;
   1499 
   1500   Optional<nonloc::LazyCompoundVal> LCV = V->getAs<nonloc::LazyCompoundVal>();
   1501   if (!LCV)
   1502     return None;
   1503 
   1504   // If the LCV is for a subregion, the types might not match, and we shouldn't
   1505   // reuse the binding.
   1506   QualType RegionTy = getUnderlyingType(R);
   1507   if (!RegionTy.isNull() &&
   1508       !RegionTy->isVoidPointerType()) {
   1509     QualType SourceRegionTy = LCV->getRegion()->getValueType();
   1510     if (!SVB.getContext().hasSameUnqualifiedType(RegionTy, SourceRegionTy))
   1511       return None;
   1512   }
   1513 
   1514   if (!AllowSubregionBindings) {
   1515     // If there are any other bindings within this region, we shouldn't reuse
   1516     // the top-level binding.
   1517     SmallVector<BindingPair, 16> Bindings;
   1518     collectSubRegionBindings(Bindings, SVB, *B.lookup(R->getBaseRegion()), R,
   1519                              /*IncludeAllDefaultBindings=*/true);
   1520     if (Bindings.size() > 1)
   1521       return None;
   1522   }
   1523 
   1524   return *LCV;
   1525 }
   1526 
   1527 
   1528 std::pair<Store, const SubRegion *>
   1529 RegionStoreManager::findLazyBinding(RegionBindingsConstRef B,
   1530                                    const SubRegion *R,
   1531                                    const SubRegion *originalRegion) {
   1532   if (originalRegion != R) {
   1533     if (Optional<nonloc::LazyCompoundVal> V =
   1534           getExistingLazyBinding(svalBuilder, B, R, true))
   1535       return std::make_pair(V->getStore(), V->getRegion());
   1536   }
   1537 
   1538   typedef std::pair<Store, const SubRegion *> StoreRegionPair;
   1539   StoreRegionPair Result = StoreRegionPair();
   1540 
   1541   if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) {
   1542     Result = findLazyBinding(B, cast<SubRegion>(ER->getSuperRegion()),
   1543                              originalRegion);
   1544 
   1545     if (Result.second)
   1546       Result.second = MRMgr.getElementRegionWithSuper(ER, Result.second);
   1547 
   1548   } else if (const FieldRegion *FR = dyn_cast<FieldRegion>(R)) {
   1549     Result = findLazyBinding(B, cast<SubRegion>(FR->getSuperRegion()),
   1550                                        originalRegion);
   1551 
   1552     if (Result.second)
   1553       Result.second = MRMgr.getFieldRegionWithSuper(FR, Result.second);
   1554 
   1555   } else if (const CXXBaseObjectRegion *BaseReg =
   1556                dyn_cast<CXXBaseObjectRegion>(R)) {
   1557     // C++ base object region is another kind of region that we should blast
   1558     // through to look for lazy compound value. It is like a field region.
   1559     Result = findLazyBinding(B, cast<SubRegion>(BaseReg->getSuperRegion()),
   1560                              originalRegion);
   1561 
   1562     if (Result.second)
   1563       Result.second = MRMgr.getCXXBaseObjectRegionWithSuper(BaseReg,
   1564                                                             Result.second);
   1565   }
   1566 
   1567   return Result;
   1568 }
   1569 
   1570 SVal RegionStoreManager::getBindingForElement(RegionBindingsConstRef B,
   1571                                               const ElementRegion* R) {
   1572   // We do not currently model bindings of the CompoundLiteralregion.
   1573   if (isa<CompoundLiteralRegion>(R->getBaseRegion()))
   1574     return UnknownVal();
   1575 
   1576   // Check if the region has a binding.
   1577   if (const Optional<SVal> &V = B.getDirectBinding(R))
   1578     return *V;
   1579 
   1580   const MemRegion* superR = R->getSuperRegion();
   1581 
   1582   // Check if the region is an element region of a string literal.
   1583   if (const StringRegion *StrR=dyn_cast<StringRegion>(superR)) {
   1584     // FIXME: Handle loads from strings where the literal is treated as
   1585     // an integer, e.g., *((unsigned int*)"hello")
   1586     QualType T = Ctx.getAsArrayType(StrR->getValueType())->getElementType();
   1587     if (!Ctx.hasSameUnqualifiedType(T, R->getElementType()))
   1588       return UnknownVal();
   1589 
   1590     const StringLiteral *Str = StrR->getStringLiteral();
   1591     SVal Idx = R->getIndex();
   1592     if (Optional<nonloc::ConcreteInt> CI = Idx.getAs<nonloc::ConcreteInt>()) {
   1593       int64_t i = CI->getValue().getSExtValue();
   1594       // Abort on string underrun.  This can be possible by arbitrary
   1595       // clients of getBindingForElement().
   1596       if (i < 0)
   1597         return UndefinedVal();
   1598       int64_t length = Str->getLength();
   1599       // Technically, only i == length is guaranteed to be null.
   1600       // However, such overflows should be caught before reaching this point;
   1601       // the only time such an access would be made is if a string literal was
   1602       // used to initialize a larger array.
   1603       char c = (i >= length) ? '\0' : Str->getCodeUnit(i);
   1604       return svalBuilder.makeIntVal(c, T);
   1605     }
   1606   }
   1607 
   1608   // Check for loads from a code text region.  For such loads, just give up.
   1609   if (isa<CodeTextRegion>(superR))
   1610     return UnknownVal();
   1611 
   1612   // Handle the case where we are indexing into a larger scalar object.
   1613   // For example, this handles:
   1614   //   int x = ...
   1615   //   char *y = &x;
   1616   //   return *y;
   1617   // FIXME: This is a hack, and doesn't do anything really intelligent yet.
   1618   const RegionRawOffset &O = R->getAsArrayOffset();
   1619 
   1620   // If we cannot reason about the offset, return an unknown value.
   1621   if (!O.getRegion())
   1622     return UnknownVal();
   1623 
   1624   if (const TypedValueRegion *baseR =
   1625         dyn_cast_or_null<TypedValueRegion>(O.getRegion())) {
   1626     QualType baseT = baseR->getValueType();
   1627     if (baseT->isScalarType()) {
   1628       QualType elemT = R->getElementType();
   1629       if (elemT->isScalarType()) {
   1630         if (Ctx.getTypeSizeInChars(baseT) >= Ctx.getTypeSizeInChars(elemT)) {
   1631           if (const Optional<SVal> &V = B.getDirectBinding(superR)) {
   1632             if (SymbolRef parentSym = V->getAsSymbol())
   1633               return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
   1634 
   1635             if (V->isUnknownOrUndef())
   1636               return *V;
   1637             // Other cases: give up.  We are indexing into a larger object
   1638             // that has some value, but we don't know how to handle that yet.
   1639             return UnknownVal();
   1640           }
   1641         }
   1642       }
   1643     }
   1644   }
   1645   return getBindingForFieldOrElementCommon(B, R, R->getElementType());
   1646 }
   1647 
   1648 SVal RegionStoreManager::getBindingForField(RegionBindingsConstRef B,
   1649                                             const FieldRegion* R) {
   1650 
   1651   // Check if the region has a binding.
   1652   if (const Optional<SVal> &V = B.getDirectBinding(R))
   1653     return *V;
   1654 
   1655   QualType Ty = R->getValueType();
   1656   return getBindingForFieldOrElementCommon(B, R, Ty);
   1657 }
   1658 
   1659 Optional<SVal>
   1660 RegionStoreManager::getBindingForDerivedDefaultValue(RegionBindingsConstRef B,
   1661                                                      const MemRegion *superR,
   1662                                                      const TypedValueRegion *R,
   1663                                                      QualType Ty) {
   1664 
   1665   if (const Optional<SVal> &D = B.getDefaultBinding(superR)) {
   1666     const SVal &val = D.getValue();
   1667     if (SymbolRef parentSym = val.getAsSymbol())
   1668       return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
   1669 
   1670     if (val.isZeroConstant())
   1671       return svalBuilder.makeZeroVal(Ty);
   1672 
   1673     if (val.isUnknownOrUndef())
   1674       return val;
   1675 
   1676     // Lazy bindings are usually handled through getExistingLazyBinding().
   1677     // We should unify these two code paths at some point.
   1678     if (val.getAs<nonloc::LazyCompoundVal>())
   1679       return val;
   1680 
   1681     llvm_unreachable("Unknown default value");
   1682   }
   1683 
   1684   return None;
   1685 }
   1686 
   1687 SVal RegionStoreManager::getLazyBinding(const SubRegion *LazyBindingRegion,
   1688                                         RegionBindingsRef LazyBinding) {
   1689   SVal Result;
   1690   if (const ElementRegion *ER = dyn_cast<ElementRegion>(LazyBindingRegion))
   1691     Result = getBindingForElement(LazyBinding, ER);
   1692   else
   1693     Result = getBindingForField(LazyBinding,
   1694                                 cast<FieldRegion>(LazyBindingRegion));
   1695 
   1696   // FIXME: This is a hack to deal with RegionStore's inability to distinguish a
   1697   // default value for /part/ of an aggregate from a default value for the
   1698   // /entire/ aggregate. The most common case of this is when struct Outer
   1699   // has as its first member a struct Inner, which is copied in from a stack
   1700   // variable. In this case, even if the Outer's default value is symbolic, 0,
   1701   // or unknown, it gets overridden by the Inner's default value of undefined.
   1702   //
   1703   // This is a general problem -- if the Inner is zero-initialized, the Outer
   1704   // will now look zero-initialized. The proper way to solve this is with a
   1705   // new version of RegionStore that tracks the extent of a binding as well
   1706   // as the offset.
   1707   //
   1708   // This hack only takes care of the undefined case because that can very
   1709   // quickly result in a warning.
   1710   if (Result.isUndef())
   1711     Result = UnknownVal();
   1712 
   1713   return Result;
   1714 }
   1715 
   1716 SVal
   1717 RegionStoreManager::getBindingForFieldOrElementCommon(RegionBindingsConstRef B,
   1718                                                       const TypedValueRegion *R,
   1719                                                       QualType Ty) {
   1720 
   1721   // At this point we have already checked in either getBindingForElement or
   1722   // getBindingForField if 'R' has a direct binding.
   1723 
   1724   // Lazy binding?
   1725   Store lazyBindingStore = nullptr;
   1726   const SubRegion *lazyBindingRegion = nullptr;
   1727   std::tie(lazyBindingStore, lazyBindingRegion) = findLazyBinding(B, R, R);
   1728   if (lazyBindingRegion)
   1729     return getLazyBinding(lazyBindingRegion,
   1730                           getRegionBindings(lazyBindingStore));
   1731 
   1732   // Record whether or not we see a symbolic index.  That can completely
   1733   // be out of scope of our lookup.
   1734   bool hasSymbolicIndex = false;
   1735 
   1736   // FIXME: This is a hack to deal with RegionStore's inability to distinguish a
   1737   // default value for /part/ of an aggregate from a default value for the
   1738   // /entire/ aggregate. The most common case of this is when struct Outer
   1739   // has as its first member a struct Inner, which is copied in from a stack
   1740   // variable. In this case, even if the Outer's default value is symbolic, 0,
   1741   // or unknown, it gets overridden by the Inner's default value of undefined.
   1742   //
   1743   // This is a general problem -- if the Inner is zero-initialized, the Outer
   1744   // will now look zero-initialized. The proper way to solve this is with a
   1745   // new version of RegionStore that tracks the extent of a binding as well
   1746   // as the offset.
   1747   //
   1748   // This hack only takes care of the undefined case because that can very
   1749   // quickly result in a warning.
   1750   bool hasPartialLazyBinding = false;
   1751 
   1752   const SubRegion *SR = dyn_cast<SubRegion>(R);
   1753   while (SR) {
   1754     const MemRegion *Base = SR->getSuperRegion();
   1755     if (Optional<SVal> D = getBindingForDerivedDefaultValue(B, Base, R, Ty)) {
   1756       if (D->getAs<nonloc::LazyCompoundVal>()) {
   1757         hasPartialLazyBinding = true;
   1758         break;
   1759       }
   1760 
   1761       return *D;
   1762     }
   1763 
   1764     if (const ElementRegion *ER = dyn_cast<ElementRegion>(Base)) {
   1765       NonLoc index = ER->getIndex();
   1766       if (!index.isConstant())
   1767         hasSymbolicIndex = true;
   1768     }
   1769 
   1770     // If our super region is a field or element itself, walk up the region
   1771     // hierarchy to see if there is a default value installed in an ancestor.
   1772     SR = dyn_cast<SubRegion>(Base);
   1773   }
   1774 
   1775   if (R->hasStackNonParametersStorage()) {
   1776     if (isa<ElementRegion>(R)) {
   1777       // Currently we don't reason specially about Clang-style vectors.  Check
   1778       // if superR is a vector and if so return Unknown.
   1779       if (const TypedValueRegion *typedSuperR =
   1780             dyn_cast<TypedValueRegion>(R->getSuperRegion())) {
   1781         if (typedSuperR->getValueType()->isVectorType())
   1782           return UnknownVal();
   1783       }
   1784     }
   1785 
   1786     // FIXME: We also need to take ElementRegions with symbolic indexes into
   1787     // account.  This case handles both directly accessing an ElementRegion
   1788     // with a symbolic offset, but also fields within an element with
   1789     // a symbolic offset.
   1790     if (hasSymbolicIndex)
   1791       return UnknownVal();
   1792 
   1793     if (!hasPartialLazyBinding)
   1794       return UndefinedVal();
   1795   }
   1796 
   1797   // All other values are symbolic.
   1798   return svalBuilder.getRegionValueSymbolVal(R);
   1799 }
   1800 
   1801 SVal RegionStoreManager::getBindingForObjCIvar(RegionBindingsConstRef B,
   1802                                                const ObjCIvarRegion* R) {
   1803   // Check if the region has a binding.
   1804   if (const Optional<SVal> &V = B.getDirectBinding(R))
   1805     return *V;
   1806 
   1807   const MemRegion *superR = R->getSuperRegion();
   1808 
   1809   // Check if the super region has a default binding.
   1810   if (const Optional<SVal> &V = B.getDefaultBinding(superR)) {
   1811     if (SymbolRef parentSym = V->getAsSymbol())
   1812       return svalBuilder.getDerivedRegionValueSymbolVal(parentSym, R);
   1813 
   1814     // Other cases: give up.
   1815     return UnknownVal();
   1816   }
   1817 
   1818   return getBindingForLazySymbol(R);
   1819 }
   1820 
   1821 SVal RegionStoreManager::getBindingForVar(RegionBindingsConstRef B,
   1822                                           const VarRegion *R) {
   1823 
   1824   // Check if the region has a binding.
   1825   if (const Optional<SVal> &V = B.getDirectBinding(R))
   1826     return *V;
   1827 
   1828   // Lazily derive a value for the VarRegion.
   1829   const VarDecl *VD = R->getDecl();
   1830   const MemSpaceRegion *MS = R->getMemorySpace();
   1831 
   1832   // Arguments are always symbolic.
   1833   if (isa<StackArgumentsSpaceRegion>(MS))
   1834     return svalBuilder.getRegionValueSymbolVal(R);
   1835 
   1836   // Is 'VD' declared constant?  If so, retrieve the constant value.
   1837   if (VD->getType().isConstQualified())
   1838     if (const Expr *Init = VD->getInit())
   1839       if (Optional<SVal> V = svalBuilder.getConstantVal(Init))
   1840         return *V;
   1841 
   1842   // This must come after the check for constants because closure-captured
   1843   // constant variables may appear in UnknownSpaceRegion.
   1844   if (isa<UnknownSpaceRegion>(MS))
   1845     return svalBuilder.getRegionValueSymbolVal(R);
   1846 
   1847   if (isa<GlobalsSpaceRegion>(MS)) {
   1848     QualType T = VD->getType();
   1849 
   1850     // Function-scoped static variables are default-initialized to 0; if they
   1851     // have an initializer, it would have been processed by now.
   1852     if (isa<StaticGlobalSpaceRegion>(MS))
   1853       return svalBuilder.makeZeroVal(T);
   1854 
   1855     if (Optional<SVal> V = getBindingForDerivedDefaultValue(B, MS, R, T)) {
   1856       assert(!V->getAs<nonloc::LazyCompoundVal>());
   1857       return V.getValue();
   1858     }
   1859 
   1860     return svalBuilder.getRegionValueSymbolVal(R);
   1861   }
   1862 
   1863   return UndefinedVal();
   1864 }
   1865 
   1866 SVal RegionStoreManager::getBindingForLazySymbol(const TypedValueRegion *R) {
   1867   // All other values are symbolic.
   1868   return svalBuilder.getRegionValueSymbolVal(R);
   1869 }
   1870 
   1871 const RegionStoreManager::SValListTy &
   1872 RegionStoreManager::getInterestingValues(nonloc::LazyCompoundVal LCV) {
   1873   // First, check the cache.
   1874   LazyBindingsMapTy::iterator I = LazyBindingsMap.find(LCV.getCVData());
   1875   if (I != LazyBindingsMap.end())
   1876     return I->second;
   1877 
   1878   // If we don't have a list of values cached, start constructing it.
   1879   SValListTy List;
   1880 
   1881   const SubRegion *LazyR = LCV.getRegion();
   1882   RegionBindingsRef B = getRegionBindings(LCV.getStore());
   1883 
   1884   // If this region had /no/ bindings at the time, there are no interesting
   1885   // values to return.
   1886   const ClusterBindings *Cluster = B.lookup(LazyR->getBaseRegion());
   1887   if (!Cluster)
   1888     return (LazyBindingsMap[LCV.getCVData()] = std::move(List));
   1889 
   1890   SmallVector<BindingPair, 32> Bindings;
   1891   collectSubRegionBindings(Bindings, svalBuilder, *Cluster, LazyR,
   1892                            /*IncludeAllDefaultBindings=*/true);
   1893   for (SmallVectorImpl<BindingPair>::const_iterator I = Bindings.begin(),
   1894                                                     E = Bindings.end();
   1895        I != E; ++I) {
   1896     SVal V = I->second;
   1897     if (V.isUnknownOrUndef() || V.isConstant())
   1898       continue;
   1899 
   1900     if (Optional<nonloc::LazyCompoundVal> InnerLCV =
   1901             V.getAs<nonloc::LazyCompoundVal>()) {
   1902       const SValListTy &InnerList = getInterestingValues(*InnerLCV);
   1903       List.insert(List.end(), InnerList.begin(), InnerList.end());
   1904       continue;
   1905     }
   1906 
   1907     List.push_back(V);
   1908   }
   1909 
   1910   return (LazyBindingsMap[LCV.getCVData()] = std::move(List));
   1911 }
   1912 
   1913 NonLoc RegionStoreManager::createLazyBinding(RegionBindingsConstRef B,
   1914                                              const TypedValueRegion *R) {
   1915   if (Optional<nonloc::LazyCompoundVal> V =
   1916         getExistingLazyBinding(svalBuilder, B, R, false))
   1917     return *V;
   1918 
   1919   return svalBuilder.makeLazyCompoundVal(StoreRef(B.asStore(), *this), R);
   1920 }
   1921 
   1922 static bool isRecordEmpty(const RecordDecl *RD) {
   1923   if (!RD->field_empty())
   1924     return false;
   1925   if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD))
   1926     return CRD->getNumBases() == 0;
   1927   return true;
   1928 }
   1929 
   1930 SVal RegionStoreManager::getBindingForStruct(RegionBindingsConstRef B,
   1931                                              const TypedValueRegion *R) {
   1932   const RecordDecl *RD = R->getValueType()->castAs<RecordType>()->getDecl();
   1933   if (!RD->getDefinition() || isRecordEmpty(RD))
   1934     return UnknownVal();
   1935 
   1936   return createLazyBinding(B, R);
   1937 }
   1938 
   1939 SVal RegionStoreManager::getBindingForArray(RegionBindingsConstRef B,
   1940                                             const TypedValueRegion *R) {
   1941   assert(Ctx.getAsConstantArrayType(R->getValueType()) &&
   1942          "Only constant array types can have compound bindings.");
   1943 
   1944   return createLazyBinding(B, R);
   1945 }
   1946 
   1947 bool RegionStoreManager::includedInBindings(Store store,
   1948                                             const MemRegion *region) const {
   1949   RegionBindingsRef B = getRegionBindings(store);
   1950   region = region->getBaseRegion();
   1951 
   1952   // Quick path: if the base is the head of a cluster, the region is live.
   1953   if (B.lookup(region))
   1954     return true;
   1955 
   1956   // Slow path: if the region is the VALUE of any binding, it is live.
   1957   for (RegionBindingsRef::iterator RI = B.begin(), RE = B.end(); RI != RE; ++RI) {
   1958     const ClusterBindings &Cluster = RI.getData();
   1959     for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
   1960          CI != CE; ++CI) {
   1961       const SVal &D = CI.getData();
   1962       if (const MemRegion *R = D.getAsRegion())
   1963         if (R->getBaseRegion() == region)
   1964           return true;
   1965     }
   1966   }
   1967 
   1968   return false;
   1969 }
   1970 
   1971 //===----------------------------------------------------------------------===//
   1972 // Binding values to regions.
   1973 //===----------------------------------------------------------------------===//
   1974 
   1975 StoreRef RegionStoreManager::killBinding(Store ST, Loc L) {
   1976   if (Optional<loc::MemRegionVal> LV = L.getAs<loc::MemRegionVal>())
   1977     if (const MemRegion* R = LV->getRegion())
   1978       return StoreRef(getRegionBindings(ST).removeBinding(R)
   1979                                            .asImmutableMap()
   1980                                            .getRootWithoutRetain(),
   1981                       *this);
   1982 
   1983   return StoreRef(ST, *this);
   1984 }
   1985 
   1986 RegionBindingsRef
   1987 RegionStoreManager::bind(RegionBindingsConstRef B, Loc L, SVal V) {
   1988   if (L.getAs<loc::ConcreteInt>())
   1989     return B;
   1990 
   1991   // If we get here, the location should be a region.
   1992   const MemRegion *R = L.castAs<loc::MemRegionVal>().getRegion();
   1993 
   1994   // Check if the region is a struct region.
   1995   if (const TypedValueRegion* TR = dyn_cast<TypedValueRegion>(R)) {
   1996     QualType Ty = TR->getValueType();
   1997     if (Ty->isArrayType())
   1998       return bindArray(B, TR, V);
   1999     if (Ty->isStructureOrClassType())
   2000       return bindStruct(B, TR, V);
   2001     if (Ty->isVectorType())
   2002       return bindVector(B, TR, V);
   2003     if (Ty->isUnionType())
   2004       return bindAggregate(B, TR, V);
   2005   }
   2006 
   2007   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R)) {
   2008     // Binding directly to a symbolic region should be treated as binding
   2009     // to element 0.
   2010     QualType T = SR->getSymbol()->getType();
   2011     if (T->isAnyPointerType() || T->isReferenceType())
   2012       T = T->getPointeeType();
   2013 
   2014     R = GetElementZeroRegion(SR, T);
   2015   }
   2016 
   2017   // Clear out bindings that may overlap with this binding.
   2018   RegionBindingsRef NewB = removeSubRegionBindings(B, cast<SubRegion>(R));
   2019   return NewB.addBinding(BindingKey::Make(R, BindingKey::Direct), V);
   2020 }
   2021 
   2022 RegionBindingsRef
   2023 RegionStoreManager::setImplicitDefaultValue(RegionBindingsConstRef B,
   2024                                             const MemRegion *R,
   2025                                             QualType T) {
   2026   SVal V;
   2027 
   2028   if (Loc::isLocType(T))
   2029     V = svalBuilder.makeNull();
   2030   else if (T->isIntegralOrEnumerationType())
   2031     V = svalBuilder.makeZeroVal(T);
   2032   else if (T->isStructureOrClassType() || T->isArrayType()) {
   2033     // Set the default value to a zero constant when it is a structure
   2034     // or array.  The type doesn't really matter.
   2035     V = svalBuilder.makeZeroVal(Ctx.IntTy);
   2036   }
   2037   else {
   2038     // We can't represent values of this type, but we still need to set a value
   2039     // to record that the region has been initialized.
   2040     // If this assertion ever fires, a new case should be added above -- we
   2041     // should know how to default-initialize any value we can symbolicate.
   2042     assert(!SymbolManager::canSymbolicate(T) && "This type is representable");
   2043     V = UnknownVal();
   2044   }
   2045 
   2046   return B.addBinding(R, BindingKey::Default, V);
   2047 }
   2048 
   2049 RegionBindingsRef
   2050 RegionStoreManager::bindArray(RegionBindingsConstRef B,
   2051                               const TypedValueRegion* R,
   2052                               SVal Init) {
   2053 
   2054   const ArrayType *AT =cast<ArrayType>(Ctx.getCanonicalType(R->getValueType()));
   2055   QualType ElementTy = AT->getElementType();
   2056   Optional<uint64_t> Size;
   2057 
   2058   if (const ConstantArrayType* CAT = dyn_cast<ConstantArrayType>(AT))
   2059     Size = CAT->getSize().getZExtValue();
   2060 
   2061   // Check if the init expr is a string literal.
   2062   if (Optional<loc::MemRegionVal> MRV = Init.getAs<loc::MemRegionVal>()) {
   2063     const StringRegion *S = cast<StringRegion>(MRV->getRegion());
   2064 
   2065     // Treat the string as a lazy compound value.
   2066     StoreRef store(B.asStore(), *this);
   2067     nonloc::LazyCompoundVal LCV = svalBuilder.makeLazyCompoundVal(store, S)
   2068         .castAs<nonloc::LazyCompoundVal>();
   2069     return bindAggregate(B, R, LCV);
   2070   }
   2071 
   2072   // Handle lazy compound values.
   2073   if (Init.getAs<nonloc::LazyCompoundVal>())
   2074     return bindAggregate(B, R, Init);
   2075 
   2076   // Remaining case: explicit compound values.
   2077 
   2078   if (Init.isUnknown())
   2079     return setImplicitDefaultValue(B, R, ElementTy);
   2080 
   2081   const nonloc::CompoundVal& CV = Init.castAs<nonloc::CompoundVal>();
   2082   nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
   2083   uint64_t i = 0;
   2084 
   2085   RegionBindingsRef NewB(B);
   2086 
   2087   for (; Size.hasValue() ? i < Size.getValue() : true ; ++i, ++VI) {
   2088     // The init list might be shorter than the array length.
   2089     if (VI == VE)
   2090       break;
   2091 
   2092     const NonLoc &Idx = svalBuilder.makeArrayIndex(i);
   2093     const ElementRegion *ER = MRMgr.getElementRegion(ElementTy, Idx, R, Ctx);
   2094 
   2095     if (ElementTy->isStructureOrClassType())
   2096       NewB = bindStruct(NewB, ER, *VI);
   2097     else if (ElementTy->isArrayType())
   2098       NewB = bindArray(NewB, ER, *VI);
   2099     else
   2100       NewB = bind(NewB, loc::MemRegionVal(ER), *VI);
   2101   }
   2102 
   2103   // If the init list is shorter than the array length, set the
   2104   // array default value.
   2105   if (Size.hasValue() && i < Size.getValue())
   2106     NewB = setImplicitDefaultValue(NewB, R, ElementTy);
   2107 
   2108   return NewB;
   2109 }
   2110 
   2111 RegionBindingsRef RegionStoreManager::bindVector(RegionBindingsConstRef B,
   2112                                                  const TypedValueRegion* R,
   2113                                                  SVal V) {
   2114   QualType T = R->getValueType();
   2115   assert(T->isVectorType());
   2116   const VectorType *VT = T->getAs<VectorType>(); // Use getAs for typedefs.
   2117 
   2118   // Handle lazy compound values and symbolic values.
   2119   if (V.getAs<nonloc::LazyCompoundVal>() || V.getAs<nonloc::SymbolVal>())
   2120     return bindAggregate(B, R, V);
   2121 
   2122   // We may get non-CompoundVal accidentally due to imprecise cast logic or
   2123   // that we are binding symbolic struct value. Kill the field values, and if
   2124   // the value is symbolic go and bind it as a "default" binding.
   2125   if (!V.getAs<nonloc::CompoundVal>()) {
   2126     return bindAggregate(B, R, UnknownVal());
   2127   }
   2128 
   2129   QualType ElemType = VT->getElementType();
   2130   nonloc::CompoundVal CV = V.castAs<nonloc::CompoundVal>();
   2131   nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
   2132   unsigned index = 0, numElements = VT->getNumElements();
   2133   RegionBindingsRef NewB(B);
   2134 
   2135   for ( ; index != numElements ; ++index) {
   2136     if (VI == VE)
   2137       break;
   2138 
   2139     NonLoc Idx = svalBuilder.makeArrayIndex(index);
   2140     const ElementRegion *ER = MRMgr.getElementRegion(ElemType, Idx, R, Ctx);
   2141 
   2142     if (ElemType->isArrayType())
   2143       NewB = bindArray(NewB, ER, *VI);
   2144     else if (ElemType->isStructureOrClassType())
   2145       NewB = bindStruct(NewB, ER, *VI);
   2146     else
   2147       NewB = bind(NewB, loc::MemRegionVal(ER), *VI);
   2148   }
   2149   return NewB;
   2150 }
   2151 
   2152 Optional<RegionBindingsRef>
   2153 RegionStoreManager::tryBindSmallStruct(RegionBindingsConstRef B,
   2154                                        const TypedValueRegion *R,
   2155                                        const RecordDecl *RD,
   2156                                        nonloc::LazyCompoundVal LCV) {
   2157   FieldVector Fields;
   2158 
   2159   if (const CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(RD))
   2160     if (Class->getNumBases() != 0 || Class->getNumVBases() != 0)
   2161       return None;
   2162 
   2163   for (const auto *FD : RD->fields()) {
   2164     if (FD->isUnnamedBitfield())
   2165       continue;
   2166 
   2167     // If there are too many fields, or if any of the fields are aggregates,
   2168     // just use the LCV as a default binding.
   2169     if (Fields.size() == SmallStructLimit)
   2170       return None;
   2171 
   2172     QualType Ty = FD->getType();
   2173     if (!(Ty->isScalarType() || Ty->isReferenceType()))
   2174       return None;
   2175 
   2176     Fields.push_back(FD);
   2177   }
   2178 
   2179   RegionBindingsRef NewB = B;
   2180 
   2181   for (FieldVector::iterator I = Fields.begin(), E = Fields.end(); I != E; ++I){
   2182     const FieldRegion *SourceFR = MRMgr.getFieldRegion(*I, LCV.getRegion());
   2183     SVal V = getBindingForField(getRegionBindings(LCV.getStore()), SourceFR);
   2184 
   2185     const FieldRegion *DestFR = MRMgr.getFieldRegion(*I, R);
   2186     NewB = bind(NewB, loc::MemRegionVal(DestFR), V);
   2187   }
   2188 
   2189   return NewB;
   2190 }
   2191 
   2192 RegionBindingsRef RegionStoreManager::bindStruct(RegionBindingsConstRef B,
   2193                                                  const TypedValueRegion* R,
   2194                                                  SVal V) {
   2195   if (!Features.supportsFields())
   2196     return B;
   2197 
   2198   QualType T = R->getValueType();
   2199   assert(T->isStructureOrClassType());
   2200 
   2201   const RecordType* RT = T->getAs<RecordType>();
   2202   const RecordDecl *RD = RT->getDecl();
   2203 
   2204   if (!RD->isCompleteDefinition())
   2205     return B;
   2206 
   2207   // Handle lazy compound values and symbolic values.
   2208   if (Optional<nonloc::LazyCompoundVal> LCV =
   2209         V.getAs<nonloc::LazyCompoundVal>()) {
   2210     if (Optional<RegionBindingsRef> NewB = tryBindSmallStruct(B, R, RD, *LCV))
   2211       return *NewB;
   2212     return bindAggregate(B, R, V);
   2213   }
   2214   if (V.getAs<nonloc::SymbolVal>())
   2215     return bindAggregate(B, R, V);
   2216 
   2217   // We may get non-CompoundVal accidentally due to imprecise cast logic or
   2218   // that we are binding symbolic struct value. Kill the field values, and if
   2219   // the value is symbolic go and bind it as a "default" binding.
   2220   if (V.isUnknown() || !V.getAs<nonloc::CompoundVal>())
   2221     return bindAggregate(B, R, UnknownVal());
   2222 
   2223   const nonloc::CompoundVal& CV = V.castAs<nonloc::CompoundVal>();
   2224   nonloc::CompoundVal::iterator VI = CV.begin(), VE = CV.end();
   2225 
   2226   RecordDecl::field_iterator FI, FE;
   2227   RegionBindingsRef NewB(B);
   2228 
   2229   for (FI = RD->field_begin(), FE = RD->field_end(); FI != FE; ++FI) {
   2230 
   2231     if (VI == VE)
   2232       break;
   2233 
   2234     // Skip any unnamed bitfields to stay in sync with the initializers.
   2235     if (FI->isUnnamedBitfield())
   2236       continue;
   2237 
   2238     QualType FTy = FI->getType();
   2239     const FieldRegion* FR = MRMgr.getFieldRegion(*FI, R);
   2240 
   2241     if (FTy->isArrayType())
   2242       NewB = bindArray(NewB, FR, *VI);
   2243     else if (FTy->isStructureOrClassType())
   2244       NewB = bindStruct(NewB, FR, *VI);
   2245     else
   2246       NewB = bind(NewB, loc::MemRegionVal(FR), *VI);
   2247     ++VI;
   2248   }
   2249 
   2250   // There may be fewer values in the initialize list than the fields of struct.
   2251   if (FI != FE) {
   2252     NewB = NewB.addBinding(R, BindingKey::Default,
   2253                            svalBuilder.makeIntVal(0, false));
   2254   }
   2255 
   2256   return NewB;
   2257 }
   2258 
   2259 RegionBindingsRef
   2260 RegionStoreManager::bindAggregate(RegionBindingsConstRef B,
   2261                                   const TypedRegion *R,
   2262                                   SVal Val) {
   2263   // Remove the old bindings, using 'R' as the root of all regions
   2264   // we will invalidate. Then add the new binding.
   2265   return removeSubRegionBindings(B, R).addBinding(R, BindingKey::Default, Val);
   2266 }
   2267 
   2268 //===----------------------------------------------------------------------===//
   2269 // State pruning.
   2270 //===----------------------------------------------------------------------===//
   2271 
   2272 namespace {
   2273 class removeDeadBindingsWorker :
   2274   public ClusterAnalysis<removeDeadBindingsWorker> {
   2275   SmallVector<const SymbolicRegion*, 12> Postponed;
   2276   SymbolReaper &SymReaper;
   2277   const StackFrameContext *CurrentLCtx;
   2278 
   2279 public:
   2280   removeDeadBindingsWorker(RegionStoreManager &rm,
   2281                            ProgramStateManager &stateMgr,
   2282                            RegionBindingsRef b, SymbolReaper &symReaper,
   2283                            const StackFrameContext *LCtx)
   2284     : ClusterAnalysis<removeDeadBindingsWorker>(rm, stateMgr, b),
   2285       SymReaper(symReaper), CurrentLCtx(LCtx) {}
   2286 
   2287   // Called by ClusterAnalysis.
   2288   void VisitAddedToCluster(const MemRegion *baseR, const ClusterBindings &C);
   2289   void VisitCluster(const MemRegion *baseR, const ClusterBindings *C);
   2290   using ClusterAnalysis<removeDeadBindingsWorker>::VisitCluster;
   2291 
   2292   using ClusterAnalysis::AddToWorkList;
   2293 
   2294   bool AddToWorkList(const MemRegion *R);
   2295 
   2296   bool UpdatePostponed();
   2297   void VisitBinding(SVal V);
   2298 };
   2299 }
   2300 
   2301 bool removeDeadBindingsWorker::AddToWorkList(const MemRegion *R) {
   2302   const MemRegion *BaseR = R->getBaseRegion();
   2303   return AddToWorkList(WorkListElement(BaseR), getCluster(BaseR));
   2304 }
   2305 
   2306 void removeDeadBindingsWorker::VisitAddedToCluster(const MemRegion *baseR,
   2307                                                    const ClusterBindings &C) {
   2308 
   2309   if (const VarRegion *VR = dyn_cast<VarRegion>(baseR)) {
   2310     if (SymReaper.isLive(VR))
   2311       AddToWorkList(baseR, &C);
   2312 
   2313     return;
   2314   }
   2315 
   2316   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(baseR)) {
   2317     if (SymReaper.isLive(SR->getSymbol()))
   2318       AddToWorkList(SR, &C);
   2319     else
   2320       Postponed.push_back(SR);
   2321 
   2322     return;
   2323   }
   2324 
   2325   if (isa<NonStaticGlobalSpaceRegion>(baseR)) {
   2326     AddToWorkList(baseR, &C);
   2327     return;
   2328   }
   2329 
   2330   // CXXThisRegion in the current or parent location context is live.
   2331   if (const CXXThisRegion *TR = dyn_cast<CXXThisRegion>(baseR)) {
   2332     const StackArgumentsSpaceRegion *StackReg =
   2333       cast<StackArgumentsSpaceRegion>(TR->getSuperRegion());
   2334     const StackFrameContext *RegCtx = StackReg->getStackFrame();
   2335     if (CurrentLCtx &&
   2336         (RegCtx == CurrentLCtx || RegCtx->isParentOf(CurrentLCtx)))
   2337       AddToWorkList(TR, &C);
   2338   }
   2339 }
   2340 
   2341 void removeDeadBindingsWorker::VisitCluster(const MemRegion *baseR,
   2342                                             const ClusterBindings *C) {
   2343   if (!C)
   2344     return;
   2345 
   2346   // Mark the symbol for any SymbolicRegion with live bindings as live itself.
   2347   // This means we should continue to track that symbol.
   2348   if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(baseR))
   2349     SymReaper.markLive(SymR->getSymbol());
   2350 
   2351   for (ClusterBindings::iterator I = C->begin(), E = C->end(); I != E; ++I) {
   2352     // Element index of a binding key is live.
   2353     SymReaper.markElementIndicesLive(I.getKey().getRegion());
   2354 
   2355     VisitBinding(I.getData());
   2356   }
   2357 }
   2358 
   2359 void removeDeadBindingsWorker::VisitBinding(SVal V) {
   2360   // Is it a LazyCompoundVal?  All referenced regions are live as well.
   2361   if (Optional<nonloc::LazyCompoundVal> LCS =
   2362           V.getAs<nonloc::LazyCompoundVal>()) {
   2363 
   2364     const RegionStoreManager::SValListTy &Vals = RM.getInterestingValues(*LCS);
   2365 
   2366     for (RegionStoreManager::SValListTy::const_iterator I = Vals.begin(),
   2367                                                         E = Vals.end();
   2368          I != E; ++I)
   2369       VisitBinding(*I);
   2370 
   2371     return;
   2372   }
   2373 
   2374   // If V is a region, then add it to the worklist.
   2375   if (const MemRegion *R = V.getAsRegion()) {
   2376     AddToWorkList(R);
   2377     SymReaper.markLive(R);
   2378 
   2379     // All regions captured by a block are also live.
   2380     if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(R)) {
   2381       BlockDataRegion::referenced_vars_iterator I = BR->referenced_vars_begin(),
   2382                                                 E = BR->referenced_vars_end();
   2383       for ( ; I != E; ++I)
   2384         AddToWorkList(I.getCapturedRegion());
   2385     }
   2386   }
   2387 
   2388 
   2389   // Update the set of live symbols.
   2390   for (SymExpr::symbol_iterator SI = V.symbol_begin(), SE = V.symbol_end();
   2391        SI!=SE; ++SI)
   2392     SymReaper.markLive(*SI);
   2393 }
   2394 
   2395 bool removeDeadBindingsWorker::UpdatePostponed() {
   2396   // See if any postponed SymbolicRegions are actually live now, after
   2397   // having done a scan.
   2398   bool changed = false;
   2399 
   2400   for (SmallVectorImpl<const SymbolicRegion*>::iterator
   2401         I = Postponed.begin(), E = Postponed.end() ; I != E ; ++I) {
   2402     if (const SymbolicRegion *SR = *I) {
   2403       if (SymReaper.isLive(SR->getSymbol())) {
   2404         changed |= AddToWorkList(SR);
   2405         *I = nullptr;
   2406       }
   2407     }
   2408   }
   2409 
   2410   return changed;
   2411 }
   2412 
   2413 StoreRef RegionStoreManager::removeDeadBindings(Store store,
   2414                                                 const StackFrameContext *LCtx,
   2415                                                 SymbolReaper& SymReaper) {
   2416   RegionBindingsRef B = getRegionBindings(store);
   2417   removeDeadBindingsWorker W(*this, StateMgr, B, SymReaper, LCtx);
   2418   W.GenerateClusters();
   2419 
   2420   // Enqueue the region roots onto the worklist.
   2421   for (SymbolReaper::region_iterator I = SymReaper.region_begin(),
   2422        E = SymReaper.region_end(); I != E; ++I) {
   2423     W.AddToWorkList(*I);
   2424   }
   2425 
   2426   do W.RunWorkList(); while (W.UpdatePostponed());
   2427 
   2428   // We have now scanned the store, marking reachable regions and symbols
   2429   // as live.  We now remove all the regions that are dead from the store
   2430   // as well as update DSymbols with the set symbols that are now dead.
   2431   for (RegionBindingsRef::iterator I = B.begin(), E = B.end(); I != E; ++I) {
   2432     const MemRegion *Base = I.getKey();
   2433 
   2434     // If the cluster has been visited, we know the region has been marked.
   2435     if (W.isVisited(Base))
   2436       continue;
   2437 
   2438     // Remove the dead entry.
   2439     B = B.remove(Base);
   2440 
   2441     if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(Base))
   2442       SymReaper.maybeDead(SymR->getSymbol());
   2443 
   2444     // Mark all non-live symbols that this binding references as dead.
   2445     const ClusterBindings &Cluster = I.getData();
   2446     for (ClusterBindings::iterator CI = Cluster.begin(), CE = Cluster.end();
   2447          CI != CE; ++CI) {
   2448       SVal X = CI.getData();
   2449       SymExpr::symbol_iterator SI = X.symbol_begin(), SE = X.symbol_end();
   2450       for (; SI != SE; ++SI)
   2451         SymReaper.maybeDead(*SI);
   2452     }
   2453   }
   2454 
   2455   return StoreRef(B.asStore(), *this);
   2456 }
   2457 
   2458 //===----------------------------------------------------------------------===//
   2459 // Utility methods.
   2460 //===----------------------------------------------------------------------===//
   2461 
   2462 void RegionStoreManager::print(Store store, raw_ostream &OS,
   2463                                const char* nl, const char *sep) {
   2464   RegionBindingsRef B = getRegionBindings(store);
   2465   OS << "Store (direct and default bindings), "
   2466      << B.asStore()
   2467      << " :" << nl;
   2468   B.dump(OS, nl);
   2469 }
   2470