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1 //= RValues.cpp - Abstract RValues for Path-Sens. Value Tracking -*- 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 SVal, Loc, and NonLoc, classes that represent
11 //  abstract r-values for use with path-sensitive value tracking.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
16 #include "clang/AST/ExprObjC.h"
17 #include "clang/Basic/IdentifierTable.h"
18 using namespace clang;
19 using namespace ento;
20 using llvm::APSInt;
21 
22 //===----------------------------------------------------------------------===//
23 // Symbol iteration within an SVal.
24 //===----------------------------------------------------------------------===//
25 
26 
27 //===----------------------------------------------------------------------===//
28 // Utility methods.
29 //===----------------------------------------------------------------------===//
30 
hasConjuredSymbol() const31 bool SVal::hasConjuredSymbol() const {
32   if (const nonloc::SymbolVal* SV = dyn_cast<nonloc::SymbolVal>(this)) {
33     SymbolRef sym = SV->getSymbol();
34     if (isa<SymbolConjured>(sym))
35       return true;
36   }
37 
38   if (const loc::MemRegionVal *RV = dyn_cast<loc::MemRegionVal>(this)) {
39     const MemRegion *R = RV->getRegion();
40     if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R)) {
41       SymbolRef sym = SR->getSymbol();
42       if (isa<SymbolConjured>(sym))
43         return true;
44     }
45   }
46 
47   return false;
48 }
49 
getAsFunctionDecl() const50 const FunctionDecl *SVal::getAsFunctionDecl() const {
51   if (const loc::MemRegionVal* X = dyn_cast<loc::MemRegionVal>(this)) {
52     const MemRegion* R = X->getRegion();
53     if (const FunctionTextRegion *CTR = R->getAs<FunctionTextRegion>())
54       return CTR->getDecl();
55   }
56 
57   return 0;
58 }
59 
60 /// \brief If this SVal is a location (subclasses Loc) and wraps a symbol,
61 /// return that SymbolRef.  Otherwise return 0.
62 ///
63 /// Implicit casts (ex: void* -> char*) can turn Symbolic region into Element
64 /// region. If that is the case, gets the underlining region.
getAsLocSymbol() const65 SymbolRef SVal::getAsLocSymbol() const {
66   // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
67   if (const nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(this))
68     return X->getLoc().getAsLocSymbol();
69 
70   if (const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this)) {
71     const MemRegion *R = X->stripCasts();
72     if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(R))
73       return SymR->getSymbol();
74   }
75   return 0;
76 }
77 
78 /// Get the symbol in the SVal or its base region.
getLocSymbolInBase() const79 SymbolRef SVal::getLocSymbolInBase() const {
80   const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this);
81 
82   if (!X)
83     return 0;
84 
85   const MemRegion *R = X->getRegion();
86 
87   while (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
88     if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SR))
89       return SymR->getSymbol();
90     else
91       R = SR->getSuperRegion();
92   }
93 
94   return 0;
95 }
96 
97 // TODO: The next 3 functions have to be simplified.
98 
99 /// \brief If this SVal wraps a symbol return that SymbolRef.
100 ///  Otherwise return 0.
getAsSymbol() const101 SymbolRef SVal::getAsSymbol() const {
102   // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
103   if (const nonloc::SymbolVal *X = dyn_cast<nonloc::SymbolVal>(this))
104     return X->getSymbol();
105 
106   return getAsLocSymbol();
107 }
108 
109 /// getAsSymbolicExpression - If this Sval wraps a symbolic expression then
110 ///  return that expression.  Otherwise return NULL.
getAsSymbolicExpression() const111 const SymExpr *SVal::getAsSymbolicExpression() const {
112   if (const nonloc::SymbolVal *X = dyn_cast<nonloc::SymbolVal>(this))
113     return X->getSymbol();
114 
115   return getAsSymbol();
116 }
117 
getAsSymExpr() const118 const SymExpr* SVal::getAsSymExpr() const {
119   const SymExpr* Sym = getAsSymbol();
120   if (!Sym)
121     Sym = getAsSymbolicExpression();
122   return Sym;
123 }
124 
getAsRegion() const125 const MemRegion *SVal::getAsRegion() const {
126   if (const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this))
127     return X->getRegion();
128 
129   if (const nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(this)) {
130     return X->getLoc().getAsRegion();
131   }
132 
133   return 0;
134 }
135 
stripCasts(bool StripBaseCasts) const136 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
137   const MemRegion *R = getRegion();
138   return R ?  R->StripCasts(StripBaseCasts) : NULL;
139 }
140 
getStore() const141 const void *nonloc::LazyCompoundVal::getStore() const {
142   return static_cast<const LazyCompoundValData*>(Data)->getStore();
143 }
144 
getRegion() const145 const TypedRegion *nonloc::LazyCompoundVal::getRegion() const {
146   return static_cast<const LazyCompoundValData*>(Data)->getRegion();
147 }
148 
149 //===----------------------------------------------------------------------===//
150 // Other Iterators.
151 //===----------------------------------------------------------------------===//
152 
begin() const153 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
154   return getValue()->begin();
155 }
156 
end() const157 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
158   return getValue()->end();
159 }
160 
161 //===----------------------------------------------------------------------===//
162 // Useful predicates.
163 //===----------------------------------------------------------------------===//
164 
isConstant() const165 bool SVal::isConstant() const {
166   return isa<nonloc::ConcreteInt>(this) || isa<loc::ConcreteInt>(this);
167 }
168 
isConstant(int I) const169 bool SVal::isConstant(int I) const {
170   if (isa<loc::ConcreteInt>(*this))
171     return cast<loc::ConcreteInt>(*this).getValue() == I;
172   else if (isa<nonloc::ConcreteInt>(*this))
173     return cast<nonloc::ConcreteInt>(*this).getValue() == I;
174   else
175     return false;
176 }
177 
isZeroConstant() const178 bool SVal::isZeroConstant() const {
179   return isConstant(0);
180 }
181 
182 
183 //===----------------------------------------------------------------------===//
184 // Transfer function dispatch for Non-Locs.
185 //===----------------------------------------------------------------------===//
186 
evalBinOp(SValBuilder & svalBuilder,BinaryOperator::Opcode Op,const nonloc::ConcreteInt & R) const187 SVal nonloc::ConcreteInt::evalBinOp(SValBuilder &svalBuilder,
188                                     BinaryOperator::Opcode Op,
189                                     const nonloc::ConcreteInt& R) const {
190   const llvm::APSInt* X =
191     svalBuilder.getBasicValueFactory().evalAPSInt(Op, getValue(), R.getValue());
192 
193   if (X)
194     return nonloc::ConcreteInt(*X);
195   else
196     return UndefinedVal();
197 }
198 
199 nonloc::ConcreteInt
evalComplement(SValBuilder & svalBuilder) const200 nonloc::ConcreteInt::evalComplement(SValBuilder &svalBuilder) const {
201   return svalBuilder.makeIntVal(~getValue());
202 }
203 
204 nonloc::ConcreteInt
evalMinus(SValBuilder & svalBuilder) const205 nonloc::ConcreteInt::evalMinus(SValBuilder &svalBuilder) const {
206   return svalBuilder.makeIntVal(-getValue());
207 }
208 
209 //===----------------------------------------------------------------------===//
210 // Transfer function dispatch for Locs.
211 //===----------------------------------------------------------------------===//
212 
evalBinOp(BasicValueFactory & BasicVals,BinaryOperator::Opcode Op,const loc::ConcreteInt & R) const213 SVal loc::ConcreteInt::evalBinOp(BasicValueFactory& BasicVals,
214                                  BinaryOperator::Opcode Op,
215                                  const loc::ConcreteInt& R) const {
216 
217   assert (Op == BO_Add || Op == BO_Sub ||
218           (Op >= BO_LT && Op <= BO_NE));
219 
220   const llvm::APSInt* X = BasicVals.evalAPSInt(Op, getValue(), R.getValue());
221 
222   if (X)
223     return loc::ConcreteInt(*X);
224   else
225     return UndefinedVal();
226 }
227 
228 //===----------------------------------------------------------------------===//
229 // Pretty-Printing.
230 //===----------------------------------------------------------------------===//
231 
dump() const232 void SVal::dump() const { dumpToStream(llvm::errs()); }
233 
dumpToStream(raw_ostream & os) const234 void SVal::dumpToStream(raw_ostream &os) const {
235   switch (getBaseKind()) {
236     case UnknownKind:
237       os << "Unknown";
238       break;
239     case NonLocKind:
240       cast<NonLoc>(this)->dumpToStream(os);
241       break;
242     case LocKind:
243       cast<Loc>(this)->dumpToStream(os);
244       break;
245     case UndefinedKind:
246       os << "Undefined";
247       break;
248   }
249 }
250 
dumpToStream(raw_ostream & os) const251 void NonLoc::dumpToStream(raw_ostream &os) const {
252   switch (getSubKind()) {
253     case nonloc::ConcreteIntKind: {
254       const nonloc::ConcreteInt& C = *cast<nonloc::ConcreteInt>(this);
255       if (C.getValue().isUnsigned())
256         os << C.getValue().getZExtValue();
257       else
258         os << C.getValue().getSExtValue();
259       os << ' ' << (C.getValue().isUnsigned() ? 'U' : 'S')
260          << C.getValue().getBitWidth() << 'b';
261       break;
262     }
263     case nonloc::SymbolValKind: {
264       os << cast<nonloc::SymbolVal>(this)->getSymbol();
265       break;
266     }
267     case nonloc::LocAsIntegerKind: {
268       const nonloc::LocAsInteger& C = *cast<nonloc::LocAsInteger>(this);
269       os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
270       break;
271     }
272     case nonloc::CompoundValKind: {
273       const nonloc::CompoundVal& C = *cast<nonloc::CompoundVal>(this);
274       os << "compoundVal{";
275       bool first = true;
276       for (nonloc::CompoundVal::iterator I=C.begin(), E=C.end(); I!=E; ++I) {
277         if (first) {
278           os << ' '; first = false;
279         }
280         else
281           os << ", ";
282 
283         (*I).dumpToStream(os);
284       }
285       os << "}";
286       break;
287     }
288     case nonloc::LazyCompoundValKind: {
289       const nonloc::LazyCompoundVal &C = *cast<nonloc::LazyCompoundVal>(this);
290       os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
291          << ',' << C.getRegion()
292          << '}';
293       break;
294     }
295     default:
296       assert (false && "Pretty-printed not implemented for this NonLoc.");
297       break;
298   }
299 }
300 
dumpToStream(raw_ostream & os) const301 void Loc::dumpToStream(raw_ostream &os) const {
302   switch (getSubKind()) {
303     case loc::ConcreteIntKind:
304       os << cast<loc::ConcreteInt>(this)->getValue().getZExtValue() << " (Loc)";
305       break;
306     case loc::GotoLabelKind:
307       os << "&&" << cast<loc::GotoLabel>(this)->getLabel()->getName();
308       break;
309     case loc::MemRegionKind:
310       os << '&' << cast<loc::MemRegionVal>(this)->getRegion()->getString();
311       break;
312     default:
313       llvm_unreachable("Pretty-printing not implemented for this Loc.");
314   }
315 }
316