SVals.cpp revision 5fc1d0c4532c55cc47ba6628f296bf5b86d2eaf0 
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"
18using namespace clang;
19using namespace ento;
20using llvm::APSInt;
21
22//===----------------------------------------------------------------------===//
23// Symbol iteration within an SVal.
24//===----------------------------------------------------------------------===//
25
26
27//===----------------------------------------------------------------------===//
28// Utility methods.
29//===----------------------------------------------------------------------===//
30
31bool 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
50const 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      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CTR->getDecl()))
55        return FD;
56  }
57
58  return 0;
59}
60
61/// \brief If this SVal is a location (subclasses Loc) and wraps a symbol,
62/// return that SymbolRef.  Otherwise return 0.
63///
64/// Implicit casts (ex: void* -> char*) can turn Symbolic region into Element
65/// region. If that is the case, gets the underlining region.
66SymbolRef SVal::getAsLocSymbol() const {
67  // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
68  if (const nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(this))
69    return X->getLoc().getAsLocSymbol();
70
71  if (const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this)) {
72    const MemRegion *R = X->stripCasts();
73    if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(R))
74      return SymR->getSymbol();
75  }
76  return 0;
77}
78
79/// Get the symbol in the SVal or its base region.
80SymbolRef SVal::getLocSymbolInBase() const {
81  const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this);
82
83  if (!X)
84    return 0;
85
86  const MemRegion *R = X->getRegion();
87
88  while (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
89    if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SR))
90      return SymR->getSymbol();
91    else
92      R = SR->getSuperRegion();
93  }
94
95  return 0;
96}
97
98// TODO: The next 3 functions have to be simplified.
99
100/// \brief If this SVal wraps a symbol return that SymbolRef.
101///  Otherwise return 0.
102SymbolRef SVal::getAsSymbol() const {
103  // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
104  if (const nonloc::SymbolVal *X = dyn_cast<nonloc::SymbolVal>(this))
105    return X->getSymbol();
106
107  return getAsLocSymbol();
108}
109
110/// getAsSymbolicExpression - If this Sval wraps a symbolic expression then
111///  return that expression.  Otherwise return NULL.
112const SymExpr *SVal::getAsSymbolicExpression() const {
113  if (const nonloc::SymbolVal *X = dyn_cast<nonloc::SymbolVal>(this))
114    return X->getSymbol();
115
116  return getAsSymbol();
117}
118
119const SymExpr* SVal::getAsSymExpr() const {
120  const SymExpr* Sym = getAsSymbol();
121  if (!Sym)
122    Sym = getAsSymbolicExpression();
123  return Sym;
124}
125
126const MemRegion *SVal::getAsRegion() const {
127  if (const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this))
128    return X->getRegion();
129
130  if (const nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(this)) {
131    return X->getLoc().getAsRegion();
132  }
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 TypedRegion *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 isa<nonloc::ConcreteInt>(this) || isa<loc::ConcreteInt>(this);
168}
169
170bool SVal::isConstant(int I) const {
171  if (isa<loc::ConcreteInt>(*this))
172    return cast<loc::ConcreteInt>(*this).getValue() == I;
173  else if (isa<nonloc::ConcreteInt>(*this))
174    return cast<nonloc::ConcreteInt>(*this).getValue() == I;
175  else
176    return false;
177}
178
179bool SVal::isZeroConstant() const {
180  return isConstant(0);
181}
182
183
184//===----------------------------------------------------------------------===//
185// Transfer function dispatch for Non-Locs.
186//===----------------------------------------------------------------------===//
187
188SVal nonloc::ConcreteInt::evalBinOp(SValBuilder &svalBuilder,
189                                    BinaryOperator::Opcode Op,
190                                    const nonloc::ConcreteInt& R) const {
191  const llvm::APSInt* X =
192    svalBuilder.getBasicValueFactory().evalAPSInt(Op, getValue(), R.getValue());
193
194  if (X)
195    return nonloc::ConcreteInt(*X);
196  else
197    return UndefinedVal();
198}
199
200nonloc::ConcreteInt
201nonloc::ConcreteInt::evalComplement(SValBuilder &svalBuilder) const {
202  return svalBuilder.makeIntVal(~getValue());
203}
204
205nonloc::ConcreteInt
206nonloc::ConcreteInt::evalMinus(SValBuilder &svalBuilder) const {
207  return svalBuilder.makeIntVal(-getValue());
208}
209
210//===----------------------------------------------------------------------===//
211// Transfer function dispatch for Locs.
212//===----------------------------------------------------------------------===//
213
214SVal loc::ConcreteInt::evalBinOp(BasicValueFactory& BasicVals,
215                                 BinaryOperator::Opcode Op,
216                                 const loc::ConcreteInt& R) const {
217
218  assert (Op == BO_Add || Op == BO_Sub ||
219          (Op >= BO_LT && Op <= BO_NE));
220
221  const llvm::APSInt* X = BasicVals.evalAPSInt(Op, getValue(), R.getValue());
222
223  if (X)
224    return loc::ConcreteInt(*X);
225  else
226    return UndefinedVal();
227}
228
229//===----------------------------------------------------------------------===//
230// Pretty-Printing.
231//===----------------------------------------------------------------------===//
232
233void SVal::dump() const { dumpToStream(llvm::errs()); }
234
235void SVal::dumpToStream(raw_ostream &os) const {
236  switch (getBaseKind()) {
237    case UnknownKind:
238      os << "Unknown";
239      break;
240    case NonLocKind:
241      cast<NonLoc>(this)->dumpToStream(os);
242      break;
243    case LocKind:
244      cast<Loc>(this)->dumpToStream(os);
245      break;
246    case UndefinedKind:
247      os << "Undefined";
248      break;
249  }
250}
251
252void NonLoc::dumpToStream(raw_ostream &os) const {
253  switch (getSubKind()) {
254    case nonloc::ConcreteIntKind: {
255      const nonloc::ConcreteInt& C = *cast<nonloc::ConcreteInt>(this);
256      if (C.getValue().isUnsigned())
257        os << C.getValue().getZExtValue();
258      else
259        os << C.getValue().getSExtValue();
260      os << ' ' << (C.getValue().isUnsigned() ? 'U' : 'S')
261         << C.getValue().getBitWidth() << 'b';
262      break;
263    }
264    case nonloc::SymbolValKind: {
265      os << cast<nonloc::SymbolVal>(this)->getSymbol();
266      break;
267    }
268    case nonloc::LocAsIntegerKind: {
269      const nonloc::LocAsInteger& C = *cast<nonloc::LocAsInteger>(this);
270      os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
271      break;
272    }
273    case nonloc::CompoundValKind: {
274      const nonloc::CompoundVal& C = *cast<nonloc::CompoundVal>(this);
275      os << "compoundVal{";
276      bool first = true;
277      for (nonloc::CompoundVal::iterator I=C.begin(), E=C.end(); I!=E; ++I) {
278        if (first) {
279          os << ' '; first = false;
280        }
281        else
282          os << ", ";
283
284        (*I).dumpToStream(os);
285      }
286      os << "}";
287      break;
288    }
289    case nonloc::LazyCompoundValKind: {
290      const nonloc::LazyCompoundVal &C = *cast<nonloc::LazyCompoundVal>(this);
291      os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
292         << ',' << C.getRegion()
293         << '}';
294      break;
295    }
296    default:
297      assert (false && "Pretty-printed not implemented for this NonLoc.");
298      break;
299  }
300}
301
302void Loc::dumpToStream(raw_ostream &os) const {
303  switch (getSubKind()) {
304    case loc::ConcreteIntKind:
305      os << cast<loc::ConcreteInt>(this)->getValue().getZExtValue() << " (Loc)";
306      break;
307    case loc::GotoLabelKind:
308      os << "&&" << cast<loc::GotoLabel>(this)->getLabel()->getName();
309      break;
310    case loc::MemRegionKind:
311      os << '&' << cast<loc::MemRegionVal>(this)->getRegion()->getString();
312      break;
313    default:
314      llvm_unreachable("Pretty-printing not implemented for this Loc.");
315  }
316}
317