SVals.cpp revision a339cd66be6202c6e86916f52a347d0289bf2eea 
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#include "llvm/Support/raw_ostream.h"
19using namespace clang;
20using namespace ento;
21using llvm::APSInt;
22
23//===----------------------------------------------------------------------===//
24// Symbol iteration within an SVal.
25//===----------------------------------------------------------------------===//
26
27
28//===----------------------------------------------------------------------===//
29// Utility methods.
30//===----------------------------------------------------------------------===//
31
32bool SVal::hasConjuredSymbol() const {
33  if (Optional<nonloc::SymbolVal> SV = getAs<nonloc::SymbolVal>()) {
34    SymbolRef sym = SV->getSymbol();
35    if (isa<SymbolConjured>(sym))
36      return true;
37  }
38
39  if (Optional<loc::MemRegionVal> RV = getAs<loc::MemRegionVal>()) {
40    const MemRegion *R = RV->getRegion();
41    if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R)) {
42      SymbolRef sym = SR->getSymbol();
43      if (isa<SymbolConjured>(sym))
44        return true;
45    }
46  }
47
48  return false;
49}
50
51const FunctionDecl *SVal::getAsFunctionDecl() const {
52  if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>()) {
53    const MemRegion* R = X->getRegion();
54    if (const FunctionTextRegion *CTR = R->getAs<FunctionTextRegion>())
55      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CTR->getDecl()))
56        return FD;
57  }
58
59  return 0;
60}
61
62/// \brief If this SVal is a location (subclasses Loc) and wraps a symbol,
63/// return that SymbolRef.  Otherwise return 0.
64///
65/// Implicit casts (ex: void* -> char*) can turn Symbolic region into Element
66/// region. If that is the case, gets the underlining region.
67SymbolRef SVal::getAsLocSymbol() const {
68  // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
69  if (Optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
70    return X->getLoc().getAsLocSymbol();
71
72  if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>()) {
73    const MemRegion *R = X->stripCasts();
74    if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(R))
75      return SymR->getSymbol();
76  }
77  return 0;
78}
79
80/// Get the symbol in the SVal or its base region.
81SymbolRef SVal::getLocSymbolInBase() const {
82  Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>();
83
84  if (!X)
85    return 0;
86
87  const MemRegion *R = X->getRegion();
88
89  while (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
90    if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SR))
91      return SymR->getSymbol();
92    else
93      R = SR->getSuperRegion();
94  }
95
96  return 0;
97}
98
99// TODO: The next 3 functions have to be simplified.
100
101/// \brief If this SVal wraps a symbol return that SymbolRef.
102///  Otherwise return 0.
103SymbolRef SVal::getAsSymbol() const {
104  // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
105  if (Optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
106    return X->getSymbol();
107
108  return getAsLocSymbol();
109}
110
111/// getAsSymbolicExpression - If this Sval wraps a symbolic expression then
112///  return that expression.  Otherwise return NULL.
113const SymExpr *SVal::getAsSymbolicExpression() const {
114  if (Optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
115    return X->getSymbol();
116
117  return getAsSymbol();
118}
119
120const SymExpr* SVal::getAsSymExpr() const {
121  const SymExpr* Sym = getAsSymbol();
122  if (!Sym)
123    Sym = getAsSymbolicExpression();
124  return Sym;
125}
126
127const MemRegion *SVal::getAsRegion() const {
128  if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>())
129    return X->getRegion();
130
131  if (Optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
132    return X->getLoc().getAsRegion();
133
134  return 0;
135}
136
137const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
138  const MemRegion *R = getRegion();
139  return R ?  R->StripCasts(StripBaseCasts) : NULL;
140}
141
142const void *nonloc::LazyCompoundVal::getStore() const {
143  return static_cast<const LazyCompoundValData*>(Data)->getStore();
144}
145
146const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
147  return static_cast<const LazyCompoundValData*>(Data)->getRegion();
148}
149
150//===----------------------------------------------------------------------===//
151// Other Iterators.
152//===----------------------------------------------------------------------===//
153
154nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
155  return getValue()->begin();
156}
157
158nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
159  return getValue()->end();
160}
161
162//===----------------------------------------------------------------------===//
163// Useful predicates.
164//===----------------------------------------------------------------------===//
165
166bool SVal::isConstant() const {
167  return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
168}
169
170bool SVal::isConstant(int I) const {
171  if (Optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
172    return LV->getValue() == I;
173  if (Optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
174    return NV->getValue() == I;
175  return false;
176}
177
178bool SVal::isZeroConstant() const {
179  return isConstant(0);
180}
181
182
183//===----------------------------------------------------------------------===//
184// Transfer function dispatch for Non-Locs.
185//===----------------------------------------------------------------------===//
186
187SVal 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
199nonloc::ConcreteInt
200nonloc::ConcreteInt::evalComplement(SValBuilder &svalBuilder) const {
201  return svalBuilder.makeIntVal(~getValue());
202}
203
204nonloc::ConcreteInt
205nonloc::ConcreteInt::evalMinus(SValBuilder &svalBuilder) const {
206  return svalBuilder.makeIntVal(-getValue());
207}
208
209//===----------------------------------------------------------------------===//
210// Transfer function dispatch for Locs.
211//===----------------------------------------------------------------------===//
212
213SVal loc::ConcreteInt::evalBinOp(BasicValueFactory& BasicVals,
214                                 BinaryOperator::Opcode Op,
215                                 const loc::ConcreteInt& R) const {
216
217  assert(BinaryOperator::isComparisonOp(Op) || Op == BO_Sub);
218
219  const llvm::APSInt *X = BasicVals.evalAPSInt(Op, getValue(), R.getValue());
220
221  if (X)
222    return nonloc::ConcreteInt(*X);
223  else
224    return UndefinedVal();
225}
226
227//===----------------------------------------------------------------------===//
228// Pretty-Printing.
229//===----------------------------------------------------------------------===//
230
231void SVal::dump() const { dumpToStream(llvm::errs()); }
232
233void SVal::dumpToStream(raw_ostream &os) const {
234  switch (getBaseKind()) {
235    case UnknownKind:
236      os << "Unknown";
237      break;
238    case NonLocKind:
239      castAs<NonLoc>().dumpToStream(os);
240      break;
241    case LocKind:
242      castAs<Loc>().dumpToStream(os);
243      break;
244    case UndefinedKind:
245      os << "Undefined";
246      break;
247  }
248}
249
250void NonLoc::dumpToStream(raw_ostream &os) const {
251  switch (getSubKind()) {
252    case nonloc::ConcreteIntKind: {
253      const nonloc::ConcreteInt& C = castAs<nonloc::ConcreteInt>();
254      if (C.getValue().isUnsigned())
255        os << C.getValue().getZExtValue();
256      else
257        os << C.getValue().getSExtValue();
258      os << ' ' << (C.getValue().isUnsigned() ? 'U' : 'S')
259         << C.getValue().getBitWidth() << 'b';
260      break;
261    }
262    case nonloc::SymbolValKind: {
263      os << castAs<nonloc::SymbolVal>().getSymbol();
264      break;
265    }
266    case nonloc::LocAsIntegerKind: {
267      const nonloc::LocAsInteger& C = castAs<nonloc::LocAsInteger>();
268      os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
269      break;
270    }
271    case nonloc::CompoundValKind: {
272      const nonloc::CompoundVal& C = castAs<nonloc::CompoundVal>();
273      os << "compoundVal{";
274      bool first = true;
275      for (nonloc::CompoundVal::iterator I=C.begin(), E=C.end(); I!=E; ++I) {
276        if (first) {
277          os << ' '; first = false;
278        }
279        else
280          os << ", ";
281
282        (*I).dumpToStream(os);
283      }
284      os << "}";
285      break;
286    }
287    case nonloc::LazyCompoundValKind: {
288      const nonloc::LazyCompoundVal &C = castAs<nonloc::LazyCompoundVal>();
289      os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
290         << ',' << C.getRegion()
291         << '}';
292      break;
293    }
294    default:
295      assert (false && "Pretty-printed not implemented for this NonLoc.");
296      break;
297  }
298}
299
300void Loc::dumpToStream(raw_ostream &os) const {
301  switch (getSubKind()) {
302    case loc::ConcreteIntKind:
303      os << castAs<loc::ConcreteInt>().getValue().getZExtValue() << " (Loc)";
304      break;
305    case loc::GotoLabelKind:
306      os << "&&" << castAs<loc::GotoLabel>().getLabel()->getName();
307      break;
308    case loc::MemRegionKind:
309      os << '&' << castAs<loc::MemRegionVal>().getRegion()->getString();
310      break;
311    default:
312      llvm_unreachable("Pretty-printing not implemented for this Loc.");
313  }
314}
315