1 // SValBuilder.h - Construction of SVals from evaluating expressions -*- 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 SValBuilder, a class that defines the interface for
11 //  "symbolical evaluators" which construct an SVal from an expression.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_GR_SVALBUILDER
16 #define LLVM_CLANG_GR_SVALBUILDER
17 
18 #include "clang/AST/ASTContext.h"
19 #include "clang/AST/Expr.h"
20 #include "clang/AST/ExprObjC.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
24 
25 namespace clang {
26 
27 class CXXBoolLiteralExpr;
28 
29 namespace ento {
30 
31 class SValBuilder {
32   virtual void anchor();
33 protected:
34   ASTContext &Context;
35 
36   /// Manager of APSInt values.
37   BasicValueFactory BasicVals;
38 
39   /// Manages the creation of symbols.
40   SymbolManager SymMgr;
41 
42   /// Manages the creation of memory regions.
43   MemRegionManager MemMgr;
44 
45   ProgramStateManager &StateMgr;
46 
47   /// The scalar type to use for array indices.
48   const QualType ArrayIndexTy;
49 
50   /// The width of the scalar type used for array indices.
51   const unsigned ArrayIndexWidth;
52 
53   virtual SVal evalCastFromNonLoc(NonLoc val, QualType castTy) = 0;
54   virtual SVal evalCastFromLoc(Loc val, QualType castTy) = 0;
55 
56 public:
57   // FIXME: Make these protected again once RegionStoreManager correctly
58   // handles loads from different bound value types.
59   virtual SVal dispatchCast(SVal val, QualType castTy) = 0;
60 
61 public:
62   SValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context,
63               ProgramStateManager &stateMgr)
64     : Context(context), BasicVals(context, alloc),
65       SymMgr(context, BasicVals, alloc),
66       MemMgr(context, alloc),
67       StateMgr(stateMgr),
68       ArrayIndexTy(context.IntTy),
69       ArrayIndexWidth(context.getTypeSize(ArrayIndexTy)) {}
70 
71   virtual ~SValBuilder() {}
72 
73   bool haveSameType(const SymExpr *Sym1, const SymExpr *Sym2) {
74     return haveSameType(Sym1->getType(), Sym2->getType());
75   }
76 
77   bool haveSameType(QualType Ty1, QualType Ty2) {
78     // FIXME: Remove the second disjunct when we support symbolic
79     // truncation/extension.
80     return (Context.getCanonicalType(Ty1) == Context.getCanonicalType(Ty2) ||
81             (Ty1->isIntegralOrEnumerationType() &&
82              Ty2->isIntegralOrEnumerationType()));
83   }
84 
85   SVal evalCast(SVal val, QualType castTy, QualType originalType);
86 
87   virtual SVal evalMinus(NonLoc val) = 0;
88 
89   virtual SVal evalComplement(NonLoc val) = 0;
90 
91   /// Create a new value which represents a binary expression with two non
92   /// location operands.
93   virtual SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op,
94                            NonLoc lhs, NonLoc rhs, QualType resultTy) = 0;
95 
96   /// Create a new value which represents a binary expression with two memory
97   /// location operands.
98   virtual SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op,
99                            Loc lhs, Loc rhs, QualType resultTy) = 0;
100 
101   /// Create a new value which represents a binary expression with a memory
102   /// location and non location operands. For example, this would be used to
103   /// evaluate a pointer arithmetic operation.
104   virtual SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op,
105                            Loc lhs, NonLoc rhs, QualType resultTy) = 0;
106 
107   /// Evaluates a given SVal. If the SVal has only one possible (integer) value,
108   /// that value is returned. Otherwise, returns NULL.
109   virtual const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal val) = 0;
110 
111   /// Constructs a symbolic expression for two non-location values.
112   SVal makeSymExprValNN(ProgramStateRef state, BinaryOperator::Opcode op,
113                       NonLoc lhs, NonLoc rhs, QualType resultTy);
114 
115   SVal evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
116                  SVal lhs, SVal rhs, QualType type);
117 
118   DefinedOrUnknownSVal evalEQ(ProgramStateRef state, DefinedOrUnknownSVal lhs,
119                               DefinedOrUnknownSVal rhs);
120 
121   ASTContext &getContext() { return Context; }
122   const ASTContext &getContext() const { return Context; }
123 
124   ProgramStateManager &getStateManager() { return StateMgr; }
125 
126   QualType getConditionType() const {
127     return Context.getLangOpts().CPlusPlus ? Context.BoolTy : Context.IntTy;
128   }
129 
130   QualType getArrayIndexType() const {
131     return ArrayIndexTy;
132   }
133 
134   BasicValueFactory &getBasicValueFactory() { return BasicVals; }
135   const BasicValueFactory &getBasicValueFactory() const { return BasicVals; }
136 
137   SymbolManager &getSymbolManager() { return SymMgr; }
138   const SymbolManager &getSymbolManager() const { return SymMgr; }
139 
140   MemRegionManager &getRegionManager() { return MemMgr; }
141   const MemRegionManager &getRegionManager() const { return MemMgr; }
142 
143   // Forwarding methods to SymbolManager.
144 
145   const SymbolConjured* conjureSymbol(const Stmt *stmt,
146                                       const LocationContext *LCtx,
147                                       QualType type,
148                                       unsigned visitCount,
149                                       const void *symbolTag = 0) {
150     return SymMgr.conjureSymbol(stmt, LCtx, type, visitCount, symbolTag);
151   }
152 
153   const SymbolConjured* conjureSymbol(const Expr *expr,
154                                       const LocationContext *LCtx,
155                                       unsigned visitCount,
156                                       const void *symbolTag = 0) {
157     return SymMgr.conjureSymbol(expr, LCtx, visitCount, symbolTag);
158   }
159 
160   /// Construct an SVal representing '0' for the specified type.
161   DefinedOrUnknownSVal makeZeroVal(QualType type);
162 
163   /// Make a unique symbol for value of region.
164   DefinedOrUnknownSVal getRegionValueSymbolVal(const TypedValueRegion *region);
165 
166   /// \brief Create a new symbol with a unique 'name'.
167   ///
168   /// We resort to conjured symbols when we cannot construct a derived symbol.
169   /// The advantage of symbols derived/built from other symbols is that we
170   /// preserve the relation between related(or even equivalent) expressions, so
171   /// conjured symbols should be used sparingly.
172   DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag,
173                                         const Expr *expr,
174                                         const LocationContext *LCtx,
175                                         unsigned count);
176   DefinedOrUnknownSVal conjureSymbolVal(const void *symbolTag,
177                                         const Expr *expr,
178                                         const LocationContext *LCtx,
179                                         QualType type,
180                                         unsigned count);
181 
182   DefinedOrUnknownSVal conjureSymbolVal(const Stmt *stmt,
183                                         const LocationContext *LCtx,
184                                         QualType type,
185                                         unsigned visitCount);
186   /// \brief Conjure a symbol representing heap allocated memory region.
187   ///
188   /// Note, the expression should represent a location.
189   DefinedOrUnknownSVal getConjuredHeapSymbolVal(const Expr *E,
190                                                 const LocationContext *LCtx,
191                                                 unsigned Count);
192 
193   DefinedOrUnknownSVal getDerivedRegionValueSymbolVal(
194       SymbolRef parentSymbol, const TypedValueRegion *region);
195 
196   DefinedSVal getMetadataSymbolVal(
197       const void *symbolTag, const MemRegion *region,
198       const Expr *expr, QualType type, unsigned count);
199 
200   DefinedSVal getFunctionPointer(const FunctionDecl *func);
201 
202   DefinedSVal getBlockPointer(const BlockDecl *block, CanQualType locTy,
203                               const LocationContext *locContext,
204                               unsigned blockCount);
205 
206   /// Returns the value of \p E, if it can be determined in a non-path-sensitive
207   /// manner.
208   ///
209   /// If \p E is not a constant or cannot be modeled, returns \c None.
210   Optional<SVal> getConstantVal(const Expr *E);
211 
212   NonLoc makeCompoundVal(QualType type, llvm::ImmutableList<SVal> vals) {
213     return nonloc::CompoundVal(BasicVals.getCompoundValData(type, vals));
214   }
215 
216   NonLoc makeLazyCompoundVal(const StoreRef &store,
217                              const TypedValueRegion *region) {
218     return nonloc::LazyCompoundVal(
219         BasicVals.getLazyCompoundValData(store, region));
220   }
221 
222   NonLoc makeZeroArrayIndex() {
223     return nonloc::ConcreteInt(BasicVals.getValue(0, ArrayIndexTy));
224   }
225 
226   NonLoc makeArrayIndex(uint64_t idx) {
227     return nonloc::ConcreteInt(BasicVals.getValue(idx, ArrayIndexTy));
228   }
229 
230   SVal convertToArrayIndex(SVal val);
231 
232   nonloc::ConcreteInt makeIntVal(const IntegerLiteral* integer) {
233     return nonloc::ConcreteInt(
234         BasicVals.getValue(integer->getValue(),
235                      integer->getType()->isUnsignedIntegerOrEnumerationType()));
236   }
237 
238   nonloc::ConcreteInt makeBoolVal(const ObjCBoolLiteralExpr *boolean) {
239     return makeTruthVal(boolean->getValue(), boolean->getType());
240   }
241 
242   nonloc::ConcreteInt makeBoolVal(const CXXBoolLiteralExpr *boolean);
243 
244   nonloc::ConcreteInt makeIntVal(const llvm::APSInt& integer) {
245     return nonloc::ConcreteInt(BasicVals.getValue(integer));
246   }
247 
248   loc::ConcreteInt makeIntLocVal(const llvm::APSInt &integer) {
249     return loc::ConcreteInt(BasicVals.getValue(integer));
250   }
251 
252   NonLoc makeIntVal(const llvm::APInt& integer, bool isUnsigned) {
253     return nonloc::ConcreteInt(BasicVals.getValue(integer, isUnsigned));
254   }
255 
256   DefinedSVal makeIntVal(uint64_t integer, QualType type) {
257     if (Loc::isLocType(type))
258       return loc::ConcreteInt(BasicVals.getValue(integer, type));
259 
260     return nonloc::ConcreteInt(BasicVals.getValue(integer, type));
261   }
262 
263   NonLoc makeIntVal(uint64_t integer, bool isUnsigned) {
264     return nonloc::ConcreteInt(BasicVals.getIntValue(integer, isUnsigned));
265   }
266 
267   NonLoc makeIntValWithPtrWidth(uint64_t integer, bool isUnsigned) {
268     return nonloc::ConcreteInt(
269         BasicVals.getIntWithPtrWidth(integer, isUnsigned));
270   }
271 
272   NonLoc makeLocAsInteger(Loc loc, unsigned bits) {
273     return nonloc::LocAsInteger(BasicVals.getPersistentSValWithData(loc, bits));
274   }
275 
276   NonLoc makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
277                     const llvm::APSInt& rhs, QualType type);
278 
279   NonLoc makeNonLoc(const llvm::APSInt& rhs, BinaryOperator::Opcode op,
280                     const SymExpr *lhs, QualType type);
281 
282   NonLoc makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
283                     const SymExpr *rhs, QualType type);
284 
285   /// \brief Create a NonLoc value for cast.
286   NonLoc makeNonLoc(const SymExpr *operand, QualType fromTy, QualType toTy);
287 
288   nonloc::ConcreteInt makeTruthVal(bool b, QualType type) {
289     return nonloc::ConcreteInt(BasicVals.getTruthValue(b, type));
290   }
291 
292   nonloc::ConcreteInt makeTruthVal(bool b) {
293     return nonloc::ConcreteInt(BasicVals.getTruthValue(b));
294   }
295 
296   Loc makeNull() {
297     return loc::ConcreteInt(BasicVals.getZeroWithPtrWidth());
298   }
299 
300   Loc makeLoc(SymbolRef sym) {
301     return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
302   }
303 
304   Loc makeLoc(const MemRegion* region) {
305     return loc::MemRegionVal(region);
306   }
307 
308   Loc makeLoc(const AddrLabelExpr *expr) {
309     return loc::GotoLabel(expr->getLabel());
310   }
311 
312   Loc makeLoc(const llvm::APSInt& integer) {
313     return loc::ConcreteInt(BasicVals.getValue(integer));
314   }
315 
316   /// Return a memory region for the 'this' object reference.
317   loc::MemRegionVal getCXXThis(const CXXMethodDecl *D,
318                                const StackFrameContext *SFC);
319 
320   /// Return a memory region for the 'this' object reference.
321   loc::MemRegionVal getCXXThis(const CXXRecordDecl *D,
322                                const StackFrameContext *SFC);
323 };
324 
325 SValBuilder* createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc,
326                                      ASTContext &context,
327                                      ProgramStateManager &stateMgr);
328 
329 } // end GR namespace
330 
331 } // end clang namespace
332 
333 #endif
334