SVals.cpp revision 25a792b0361d80337c75a14320f5be1b210066dc 
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/GRState.h"
16#include "clang/AST/ExprObjC.h"
17#include "clang/Basic/IdentifierTable.h"
18
19using namespace clang;
20using namespace ento;
21using llvm::dyn_cast;
22using llvm::cast;
23using llvm::APSInt;
24
25//===----------------------------------------------------------------------===//
26// Symbol iteration within an SVal.
27//===----------------------------------------------------------------------===//
28
29
30//===----------------------------------------------------------------------===//
31// Utility methods.
32//===----------------------------------------------------------------------===//
33
34bool SVal::hasConjuredSymbol() const {
35  if (const nonloc::SymbolVal* SV = dyn_cast<nonloc::SymbolVal>(this)) {
36    SymbolRef sym = SV->getSymbol();
37    if (isa<SymbolConjured>(sym))
38      return true;
39  }
40
41  if (const loc::MemRegionVal *RV = dyn_cast<loc::MemRegionVal>(this)) {
42    const MemRegion *R = RV->getRegion();
43    if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R)) {
44      SymbolRef sym = SR->getSymbol();
45      if (isa<SymbolConjured>(sym))
46        return true;
47    }
48  }
49
50  return false;
51}
52
53const FunctionDecl *SVal::getAsFunctionDecl() const {
54  if (const loc::MemRegionVal* X = dyn_cast<loc::MemRegionVal>(this)) {
55    const MemRegion* R = X->getRegion();
56    if (const FunctionTextRegion *CTR = R->getAs<FunctionTextRegion>())
57      return CTR->getDecl();
58  }
59
60  return NULL;
61}
62
63/// getAsLocSymbol - If this SVal is a location (subclasses Loc) and
64///  wraps a symbol, return that SymbolRef.  Otherwise return 0.
65// FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
66SymbolRef SVal::getAsLocSymbol() const {
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 NULL;
76}
77
78/// Get the symbol in the SVal or its base region.
79SymbolRef 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/// getAsSymbol - If this Sval wraps a symbol return that SymbolRef.
98///  Otherwise return 0.
99// FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
100SymbolRef SVal::getAsSymbol() const {
101  if (const nonloc::SymbolVal *X = dyn_cast<nonloc::SymbolVal>(this))
102    return X->getSymbol();
103
104  if (const nonloc::SymExprVal *X = dyn_cast<nonloc::SymExprVal>(this))
105    if (SymbolRef Y = dyn_cast<SymbolData>(X->getSymbolicExpression()))
106      return Y;
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 (const nonloc::SymExprVal *X = dyn_cast<nonloc::SymExprVal>(this))
115    return X->getSymbolicExpression();
116
117  return getAsSymbol();
118}
119
120const MemRegion *SVal::getAsRegion() const {
121  if (const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this))
122    return X->getRegion();
123
124  if (const nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(this)) {
125    return X->getLoc().getAsRegion();
126  }
127
128  return 0;
129}
130
131const MemRegion *loc::MemRegionVal::stripCasts() const {
132  const MemRegion *R = getRegion();
133  return R ?  R->StripCasts() : NULL;
134}
135
136bool SVal::symbol_iterator::operator==(const symbol_iterator &X) const {
137  return itr == X.itr;
138}
139
140bool SVal::symbol_iterator::operator!=(const symbol_iterator &X) const {
141  return itr != X.itr;
142}
143
144SVal::symbol_iterator::symbol_iterator(const SymExpr *SE) {
145  itr.push_back(SE);
146  while (!isa<SymbolData>(itr.back())) expand();
147}
148
149SVal::symbol_iterator& SVal::symbol_iterator::operator++() {
150  assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
151  assert(isa<SymbolData>(itr.back()));
152  itr.pop_back();
153  if (!itr.empty())
154    while (!isa<SymbolData>(itr.back())) expand();
155  return *this;
156}
157
158SymbolRef SVal::symbol_iterator::operator*() {
159  assert(!itr.empty() && "attempting to dereference an 'end' iterator");
160  return cast<SymbolData>(itr.back());
161}
162
163void SVal::symbol_iterator::expand() {
164  const SymExpr *SE = itr.back();
165  itr.pop_back();
166
167  if (const SymIntExpr *SIE = dyn_cast<SymIntExpr>(SE)) {
168    itr.push_back(SIE->getLHS());
169    return;
170  }
171  else if (const SymSymExpr *SSE = dyn_cast<SymSymExpr>(SE)) {
172    itr.push_back(SSE->getLHS());
173    itr.push_back(SSE->getRHS());
174    return;
175  }
176
177  assert(false && "unhandled expansion case");
178}
179
180const void *nonloc::LazyCompoundVal::getStore() const {
181  return static_cast<const LazyCompoundValData*>(Data)->getStore();
182}
183
184const TypedRegion *nonloc::LazyCompoundVal::getRegion() const {
185  return static_cast<const LazyCompoundValData*>(Data)->getRegion();
186}
187
188//===----------------------------------------------------------------------===//
189// Other Iterators.
190//===----------------------------------------------------------------------===//
191
192nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
193  return getValue()->begin();
194}
195
196nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
197  return getValue()->end();
198}
199
200//===----------------------------------------------------------------------===//
201// Useful predicates.
202//===----------------------------------------------------------------------===//
203
204bool SVal::isConstant() const {
205  return isa<nonloc::ConcreteInt>(this) || isa<loc::ConcreteInt>(this);
206}
207
208bool SVal::isConstant(int I) const {
209  if (isa<loc::ConcreteInt>(*this))
210    return cast<loc::ConcreteInt>(*this).getValue() == I;
211  else if (isa<nonloc::ConcreteInt>(*this))
212    return cast<nonloc::ConcreteInt>(*this).getValue() == I;
213  else
214    return false;
215}
216
217bool SVal::isZeroConstant() const {
218  return isConstant(0);
219}
220
221
222//===----------------------------------------------------------------------===//
223// Transfer function dispatch for Non-Locs.
224//===----------------------------------------------------------------------===//
225
226SVal nonloc::ConcreteInt::evalBinOp(SValBuilder &svalBuilder,
227                                    BinaryOperator::Opcode Op,
228                                    const nonloc::ConcreteInt& R) const {
229  const llvm::APSInt* X =
230    svalBuilder.getBasicValueFactory().evalAPSInt(Op, getValue(), R.getValue());
231
232  if (X)
233    return nonloc::ConcreteInt(*X);
234  else
235    return UndefinedVal();
236}
237
238nonloc::ConcreteInt
239nonloc::ConcreteInt::evalComplement(SValBuilder &svalBuilder) const {
240  return svalBuilder.makeIntVal(~getValue());
241}
242
243nonloc::ConcreteInt
244nonloc::ConcreteInt::evalMinus(SValBuilder &svalBuilder) const {
245  return svalBuilder.makeIntVal(-getValue());
246}
247
248//===----------------------------------------------------------------------===//
249// Transfer function dispatch for Locs.
250//===----------------------------------------------------------------------===//
251
252SVal loc::ConcreteInt::evalBinOp(BasicValueFactory& BasicVals,
253                                 BinaryOperator::Opcode Op,
254                                 const loc::ConcreteInt& R) const {
255
256  assert (Op == BO_Add || Op == BO_Sub ||
257          (Op >= BO_LT && Op <= BO_NE));
258
259  const llvm::APSInt* X = BasicVals.evalAPSInt(Op, getValue(), R.getValue());
260
261  if (X)
262    return loc::ConcreteInt(*X);
263  else
264    return UndefinedVal();
265}
266
267//===----------------------------------------------------------------------===//
268// Pretty-Printing.
269//===----------------------------------------------------------------------===//
270
271void SVal::dump() const { dumpToStream(llvm::errs()); }
272
273void SVal::dumpToStream(llvm::raw_ostream& os) const {
274  switch (getBaseKind()) {
275    case UnknownKind:
276      os << "Unknown";
277      break;
278    case NonLocKind:
279      cast<NonLoc>(this)->dumpToStream(os);
280      break;
281    case LocKind:
282      cast<Loc>(this)->dumpToStream(os);
283      break;
284    case UndefinedKind:
285      os << "Undefined";
286      break;
287    default:
288      assert (false && "Invalid SVal.");
289  }
290}
291
292void NonLoc::dumpToStream(llvm::raw_ostream& os) const {
293  switch (getSubKind()) {
294    case nonloc::ConcreteIntKind: {
295      const nonloc::ConcreteInt& C = *cast<nonloc::ConcreteInt>(this);
296      if (C.getValue().isUnsigned())
297        os << C.getValue().getZExtValue();
298      else
299        os << C.getValue().getSExtValue();
300      os << ' ' << (C.getValue().isUnsigned() ? 'U' : 'S')
301         << C.getValue().getBitWidth() << 'b';
302      break;
303    }
304    case nonloc::SymbolValKind:
305      os << '$' << cast<nonloc::SymbolVal>(this)->getSymbol();
306      break;
307    case nonloc::SymExprValKind: {
308      const nonloc::SymExprVal& C = *cast<nonloc::SymExprVal>(this);
309      const SymExpr *SE = C.getSymbolicExpression();
310      os << SE;
311      break;
312    }
313    case nonloc::LocAsIntegerKind: {
314      const nonloc::LocAsInteger& C = *cast<nonloc::LocAsInteger>(this);
315      os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
316      break;
317    }
318    case nonloc::CompoundValKind: {
319      const nonloc::CompoundVal& C = *cast<nonloc::CompoundVal>(this);
320      os << "compoundVal{";
321      bool first = true;
322      for (nonloc::CompoundVal::iterator I=C.begin(), E=C.end(); I!=E; ++I) {
323        if (first) {
324          os << ' '; first = false;
325        }
326        else
327          os << ", ";
328
329        (*I).dumpToStream(os);
330      }
331      os << "}";
332      break;
333    }
334    case nonloc::LazyCompoundValKind: {
335      const nonloc::LazyCompoundVal &C = *cast<nonloc::LazyCompoundVal>(this);
336      os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
337         << ',' << C.getRegion()
338         << '}';
339      break;
340    }
341    default:
342      assert (false && "Pretty-printed not implemented for this NonLoc.");
343      break;
344  }
345}
346
347void Loc::dumpToStream(llvm::raw_ostream& os) const {
348  switch (getSubKind()) {
349    case loc::ConcreteIntKind:
350      os << cast<loc::ConcreteInt>(this)->getValue().getZExtValue() << " (Loc)";
351      break;
352    case loc::GotoLabelKind:
353      os << "&&" << cast<loc::GotoLabel>(this)->getLabel()->getName();
354      break;
355    case loc::MemRegionKind:
356      os << '&' << cast<loc::MemRegionVal>(this)->getRegion()->getString();
357      break;
358    case loc::ObjCPropRefKind: {
359      const ObjCPropertyRefExpr *E = cast<loc::ObjCPropRef>(this)->getPropRefExpr();
360      os << "objc-prop{";
361      if (E->isSuperReceiver())
362        os << "super.";
363      else if (E->getBase())
364        os << "<base>.";
365
366      if (E->isImplicitProperty())
367        os << E->getImplicitPropertyGetter()->getSelector().getAsString();
368      else
369        os << E->getExplicitProperty()->getName();
370
371      os << "}";
372      break;
373    }
374    default:
375      assert(false && "Pretty-printing not implemented for this Loc.");
376      break;
377  }
378}
379