1//===- Store.h - Interface for maps from Locations to Values ----*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file defined the types Store and StoreManager.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_STORE_H
14#define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_STORE_H
15
16#include "clang/AST/Type.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
20#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
21#include "clang/StaticAnalyzer/Core/PathSensitive/StoreRef.h"
22#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
23#include "clang/Basic/LLVM.h"
24#include "llvm/ADT/ArrayRef.h"
25#include "llvm/ADT/DenseSet.h"
26#include "llvm/ADT/SmallVector.h"
27#include <cassert>
28#include <cstdint>
29#include <memory>
30#include <optional>
31
32namespace clang {
33
34class ASTContext;
35class CastExpr;
36class CompoundLiteralExpr;
37class CXXBasePath;
38class Decl;
39class Expr;
40class LocationContext;
41class ObjCIvarDecl;
42class StackFrameContext;
43
44namespace ento {
45
46class CallEvent;
47class ProgramStateManager;
48class ScanReachableSymbols;
49class SymbolReaper;
50
51using InvalidatedSymbols = llvm::DenseSet<SymbolRef>;
52
53class StoreManager {
54protected:
55  SValBuilder &svalBuilder;
56  ProgramStateManager &StateMgr;
57
58  /// MRMgr - Manages region objects associated with this StoreManager.
59  MemRegionManager &MRMgr;
60  ASTContext &Ctx;
61
62  StoreManager(ProgramStateManager &stateMgr);
63
64public:
65  virtual ~StoreManager() = default;
66
67  /// Return the value bound to specified location in a given state.
68  /// \param[in] store The store in which to make the lookup.
69  /// \param[in] loc The symbolic memory location.
70  /// \param[in] T An optional type that provides a hint indicating the
71  ///   expected type of the returned value.  This is used if the value is
72  ///   lazily computed.
73  /// \return The value bound to the location \c loc.
74  virtual SVal getBinding(Store store, Loc loc, QualType T = QualType()) = 0;
75
76  /// Return the default value bound to a region in a given store. The default
77  /// binding is the value of sub-regions that were not initialized separately
78  /// from their base region. For example, if the structure is zero-initialized
79  /// upon construction, this method retrieves the concrete zero value, even if
80  /// some or all fields were later overwritten manually. Default binding may be
81  /// an unknown, undefined, concrete, or symbolic value.
82  /// \param[in] store The store in which to make the lookup.
83  /// \param[in] R The region to find the default binding for.
84  /// \return The default value bound to the region in the store, if a default
85  /// binding exists.
86  virtual std::optional<SVal> getDefaultBinding(Store store,
87                                                const MemRegion *R) = 0;
88
89  /// Return the default value bound to a LazyCompoundVal. The default binding
90  /// is used to represent the value of any fields or elements within the
91  /// structure represented by the LazyCompoundVal which were not initialized
92  /// explicitly separately from the whole structure. Default binding may be an
93  /// unknown, undefined, concrete, or symbolic value.
94  /// \param[in] lcv The lazy compound value.
95  /// \return The default value bound to the LazyCompoundVal \c lcv, if a
96  /// default binding exists.
97  std::optional<SVal> getDefaultBinding(nonloc::LazyCompoundVal lcv) {
98    return getDefaultBinding(lcv.getStore(), lcv.getRegion());
99  }
100
101  /// Return a store with the specified value bound to the given location.
102  /// \param[in] store The store in which to make the binding.
103  /// \param[in] loc The symbolic memory location.
104  /// \param[in] val The value to bind to location \c loc.
105  /// \return A StoreRef object that contains the same
106  ///   bindings as \c store with the addition of having the value specified
107  ///   by \c val bound to the location given for \c loc.
108  virtual StoreRef Bind(Store store, Loc loc, SVal val) = 0;
109
110  /// Return a store with the specified value bound to all sub-regions of the
111  /// region. The region must not have previous bindings. If you need to
112  /// invalidate existing bindings, consider invalidateRegions().
113  virtual StoreRef BindDefaultInitial(Store store, const MemRegion *R,
114                                      SVal V) = 0;
115
116  /// Return a store with in which all values within the given region are
117  /// reset to zero. This method is allowed to overwrite previous bindings.
118  virtual StoreRef BindDefaultZero(Store store, const MemRegion *R) = 0;
119
120  /// Create a new store with the specified binding removed.
121  /// \param ST the original store, that is the basis for the new store.
122  /// \param L the location whose binding should be removed.
123  virtual StoreRef killBinding(Store ST, Loc L) = 0;
124
125  /// getInitialStore - Returns the initial "empty" store representing the
126  ///  value bindings upon entry to an analyzed function.
127  virtual StoreRef getInitialStore(const LocationContext *InitLoc) = 0;
128
129  /// getRegionManager - Returns the internal RegionManager object that is
130  ///  used to query and manipulate MemRegion objects.
131  MemRegionManager& getRegionManager() { return MRMgr; }
132
133  SValBuilder& getSValBuilder() { return svalBuilder; }
134
135  virtual Loc getLValueVar(const VarDecl *VD, const LocationContext *LC) {
136    return svalBuilder.makeLoc(MRMgr.getVarRegion(VD, LC));
137  }
138
139  Loc getLValueCompoundLiteral(const CompoundLiteralExpr *CL,
140                               const LocationContext *LC) {
141    return loc::MemRegionVal(MRMgr.getCompoundLiteralRegion(CL, LC));
142  }
143
144  virtual SVal getLValueIvar(const ObjCIvarDecl *decl, SVal base);
145
146  virtual SVal getLValueField(const FieldDecl *D, SVal Base) {
147    return getLValueFieldOrIvar(D, Base);
148  }
149
150  virtual SVal getLValueElement(QualType elementType, NonLoc offset, SVal Base);
151
152  /// ArrayToPointer - Used by ExprEngine::VistCast to handle implicit
153  ///  conversions between arrays and pointers.
154  virtual SVal ArrayToPointer(Loc Array, QualType ElementTy) = 0;
155
156  /// Evaluates a chain of derived-to-base casts through the path specified in
157  /// \p Cast.
158  SVal evalDerivedToBase(SVal Derived, const CastExpr *Cast);
159
160  /// Evaluates a chain of derived-to-base casts through the specified path.
161  SVal evalDerivedToBase(SVal Derived, const CXXBasePath &CastPath);
162
163  /// Evaluates a derived-to-base cast through a single level of derivation.
164  SVal evalDerivedToBase(SVal Derived, QualType DerivedPtrType,
165                         bool IsVirtual);
166
167  /// Attempts to do a down cast. Used to model BaseToDerived and C++
168  ///        dynamic_cast.
169  /// The callback may result in the following 3 scenarios:
170  ///  - Successful cast (ex: derived is subclass of base).
171  ///  - Failed cast (ex: derived is definitely not a subclass of base).
172  ///    The distinction of this case from the next one is necessary to model
173  ///    dynamic_cast.
174  ///  - We don't know (base is a symbolic region and we don't have
175  ///    enough info to determine if the cast will succeed at run time).
176  /// The function returns an optional with SVal representing the derived class
177  /// in case of a successful cast and `std::nullopt` otherwise.
178  std::optional<SVal> evalBaseToDerived(SVal Base, QualType DerivedPtrType);
179
180  const ElementRegion *GetElementZeroRegion(const SubRegion *R, QualType T);
181
182  /// castRegion - Used by ExprEngine::VisitCast to handle casts from
183  ///  a MemRegion* to a specific location type.  'R' is the region being
184  ///  casted and 'CastToTy' the result type of the cast.
185  std::optional<const MemRegion *> castRegion(const MemRegion *region,
186                                              QualType CastToTy);
187
188  virtual StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx,
189                                      SymbolReaper &SymReaper) = 0;
190
191  virtual bool includedInBindings(Store store,
192                                  const MemRegion *region) const = 0;
193
194  /// If the StoreManager supports it, increment the reference count of
195  /// the specified Store object.
196  virtual void incrementReferenceCount(Store store) {}
197
198  /// If the StoreManager supports it, decrement the reference count of
199  /// the specified Store object.  If the reference count hits 0, the memory
200  /// associated with the object is recycled.
201  virtual void decrementReferenceCount(Store store) {}
202
203  using InvalidatedRegions = SmallVector<const MemRegion *, 8>;
204
205  /// invalidateRegions - Clears out the specified regions from the store,
206  ///  marking their values as unknown. Depending on the store, this may also
207  ///  invalidate additional regions that may have changed based on accessing
208  ///  the given regions. Optionally, invalidates non-static globals as well.
209  /// \param[in] store The initial store
210  /// \param[in] Values The values to invalidate.
211  /// \param[in] E The current statement being evaluated. Used to conjure
212  ///   symbols to mark the values of invalidated regions.
213  /// \param[in] Count The current block count. Used to conjure
214  ///   symbols to mark the values of invalidated regions.
215  /// \param[in] Call The call expression which will be used to determine which
216  ///   globals should get invalidated.
217  /// \param[in,out] IS A set to fill with any symbols that are no longer
218  ///   accessible. Pass \c NULL if this information will not be used.
219  /// \param[in] ITraits Information about invalidation for a particular
220  ///   region/symbol.
221  /// \param[in,out] InvalidatedTopLevel A vector to fill with regions
222  ////  explicitly being invalidated. Pass \c NULL if this
223  ///   information will not be used.
224  /// \param[in,out] Invalidated A vector to fill with any regions being
225  ///   invalidated. This should include any regions explicitly invalidated
226  ///   even if they do not currently have bindings. Pass \c NULL if this
227  ///   information will not be used.
228  virtual StoreRef invalidateRegions(Store store,
229                                  ArrayRef<SVal> Values,
230                                  const Expr *E, unsigned Count,
231                                  const LocationContext *LCtx,
232                                  const CallEvent *Call,
233                                  InvalidatedSymbols &IS,
234                                  RegionAndSymbolInvalidationTraits &ITraits,
235                                  InvalidatedRegions *InvalidatedTopLevel,
236                                  InvalidatedRegions *Invalidated) = 0;
237
238  /// enterStackFrame - Let the StoreManager to do something when execution
239  /// engine is about to execute into a callee.
240  StoreRef enterStackFrame(Store store,
241                           const CallEvent &Call,
242                           const StackFrameContext *CalleeCtx);
243
244  /// Finds the transitive closure of symbols within the given region.
245  ///
246  /// Returns false if the visitor aborted the scan.
247  virtual bool scanReachableSymbols(Store S, const MemRegion *R,
248                                    ScanReachableSymbols &Visitor) = 0;
249
250  virtual void printJson(raw_ostream &Out, Store S, const char *NL,
251                         unsigned int Space, bool IsDot) const = 0;
252
253  class BindingsHandler {
254  public:
255    virtual ~BindingsHandler();
256
257    /// \return whether the iteration should continue.
258    virtual bool HandleBinding(StoreManager& SMgr, Store store,
259                               const MemRegion *region, SVal val) = 0;
260  };
261
262  class FindUniqueBinding : public BindingsHandler {
263    SymbolRef Sym;
264    const MemRegion* Binding = nullptr;
265    bool First = true;
266
267  public:
268    FindUniqueBinding(SymbolRef sym) : Sym(sym) {}
269
270    explicit operator bool() { return First && Binding; }
271
272    bool HandleBinding(StoreManager& SMgr, Store store, const MemRegion* R,
273                       SVal val) override;
274    const MemRegion *getRegion() { return Binding; }
275  };
276
277  /// iterBindings - Iterate over the bindings in the Store.
278  virtual void iterBindings(Store store, BindingsHandler& f) = 0;
279
280protected:
281  const ElementRegion *MakeElementRegion(const SubRegion *baseRegion,
282                                         QualType pointeeTy,
283                                         uint64_t index = 0);
284
285private:
286  SVal getLValueFieldOrIvar(const Decl *decl, SVal base);
287};
288
289inline StoreRef::StoreRef(Store store, StoreManager & smgr)
290    : store(store), mgr(smgr) {
291  if (store)
292    mgr.incrementReferenceCount(store);
293}
294
295inline StoreRef::StoreRef(const StoreRef &sr)
296    : store(sr.store), mgr(sr.mgr)
297{
298  if (store)
299    mgr.incrementReferenceCount(store);
300}
301
302inline StoreRef::~StoreRef() {
303  if (store)
304    mgr.decrementReferenceCount(store);
305}
306
307inline StoreRef &StoreRef::operator=(StoreRef const &newStore) {
308  assert(&newStore.mgr == &mgr);
309  if (store != newStore.store) {
310    mgr.incrementReferenceCount(newStore.store);
311    mgr.decrementReferenceCount(store);
312    store = newStore.getStore();
313  }
314  return *this;
315}
316
317// FIXME: Do we need to pass ProgramStateManager anymore?
318std::unique_ptr<StoreManager>
319CreateRegionStoreManager(ProgramStateManager &StMgr);
320
321} // namespace ento
322
323} // namespace clang
324
325#endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_STORE_H
326