1 //===- RValues.cpp - Abstract RValues for Path-Sens. Value Tracking -------===//
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/SVals.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/Type.h"
20 #include "clang/Basic/LLVM.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
26 #include "llvm/ADT/Optional.h"
27 #include "llvm/Support/Casting.h"
28 #include "llvm/Support/Compiler.h"
29 #include "llvm/Support/ErrorHandling.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include <cassert>
32 
33 using namespace clang;
34 using namespace ento;
35 
36 //===----------------------------------------------------------------------===//
37 // Symbol iteration within an SVal.
38 //===----------------------------------------------------------------------===//
39 
40 //===----------------------------------------------------------------------===//
41 // Utility methods.
42 //===----------------------------------------------------------------------===//
43 
44 bool SVal::hasConjuredSymbol() const {
45   if (Optional<nonloc::SymbolVal> SV = getAs<nonloc::SymbolVal>()) {
46     SymbolRef sym = SV->getSymbol();
47     if (isa<SymbolConjured>(sym))
48       return true;
49   }
50 
51   if (Optional<loc::MemRegionVal> RV = getAs<loc::MemRegionVal>()) {
52     const MemRegion *R = RV->getRegion();
53     if (const auto *SR = dyn_cast<SymbolicRegion>(R)) {
54       SymbolRef sym = SR->getSymbol();
55       if (isa<SymbolConjured>(sym))
56         return true;
57     }
58   }
59 
60   return false;
61 }
62 
63 const FunctionDecl *SVal::getAsFunctionDecl() const {
64   if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>()) {
65     const MemRegion* R = X->getRegion();
66     if (const FunctionCodeRegion *CTR = R->getAs<FunctionCodeRegion>())
67       if (const auto *FD = dyn_cast<FunctionDecl>(CTR->getDecl()))
68         return FD;
69   }
70 
71   if (auto X = getAs<nonloc::PointerToMember>()) {
72     if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(X->getDecl()))
73       return MD;
74   }
75   return nullptr;
76 }
77 
78 /// If this SVal is a location (subclasses Loc) and wraps a symbol,
79 /// return that SymbolRef.  Otherwise return 0.
80 ///
81 /// Implicit casts (ex: void* -> char*) can turn Symbolic region into Element
82 /// region. If that is the case, gets the underlining region.
83 /// When IncludeBaseRegions is set to true and the SubRegion is non-symbolic,
84 /// the first symbolic parent region is returned.
85 SymbolRef SVal::getAsLocSymbol(bool IncludeBaseRegions) const {
86   // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
87   if (Optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
88     return X->getLoc().getAsLocSymbol(IncludeBaseRegions);
89 
90   if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>()) {
91     const MemRegion *R = X->getRegion();
92     if (const SymbolicRegion *SymR = IncludeBaseRegions ?
93                                       R->getSymbolicBase() :
94                                       dyn_cast<SymbolicRegion>(R->StripCasts()))
95       return SymR->getSymbol();
96   }
97   return nullptr;
98 }
99 
100 /// Get the symbol in the SVal or its base region.
101 SymbolRef SVal::getLocSymbolInBase() const {
102   Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>();
103 
104   if (!X)
105     return nullptr;
106 
107   const MemRegion *R = X->getRegion();
108 
109   while (const auto *SR = dyn_cast<SubRegion>(R)) {
110     if (const auto *SymR = dyn_cast<SymbolicRegion>(SR))
111       return SymR->getSymbol();
112     else
113       R = SR->getSuperRegion();
114   }
115 
116   return nullptr;
117 }
118 
119 // TODO: The next 3 functions have to be simplified.
120 
121 /// If this SVal wraps a symbol return that SymbolRef.
122 /// Otherwise, return 0.
123 ///
124 /// Casts are ignored during lookup.
125 /// \param IncludeBaseRegions The boolean that controls whether the search
126 /// should continue to the base regions if the region is not symbolic.
127 SymbolRef SVal::getAsSymbol(bool IncludeBaseRegions) const {
128   // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
129   if (Optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
130     return X->getSymbol();
131 
132   return getAsLocSymbol(IncludeBaseRegions);
133 }
134 
135 /// getAsSymbolicExpression - If this Sval wraps a symbolic expression then
136 ///  return that expression.  Otherwise return NULL.
137 const SymExpr *SVal::getAsSymbolicExpression() const {
138   if (Optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
139     return X->getSymbol();
140 
141   return getAsSymbol();
142 }
143 
144 const SymExpr* SVal::getAsSymExpr() const {
145   const SymExpr* Sym = getAsSymbol();
146   if (!Sym)
147     Sym = getAsSymbolicExpression();
148   return Sym;
149 }
150 
151 const MemRegion *SVal::getAsRegion() const {
152   if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>())
153     return X->getRegion();
154 
155   if (Optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
156     return X->getLoc().getAsRegion();
157 
158   return nullptr;
159 }
160 
161 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
162   const MemRegion *R = getRegion();
163   return R ?  R->StripCasts(StripBaseCasts) : nullptr;
164 }
165 
166 const void *nonloc::LazyCompoundVal::getStore() const {
167   return static_cast<const LazyCompoundValData*>(Data)->getStore();
168 }
169 
170 const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
171   return static_cast<const LazyCompoundValData*>(Data)->getRegion();
172 }
173 
174 const DeclaratorDecl *nonloc::PointerToMember::getDecl() const {
175   const auto PTMD = this->getPTMData();
176   if (PTMD.isNull())
177     return nullptr;
178 
179   const DeclaratorDecl *DD = nullptr;
180   if (PTMD.is<const DeclaratorDecl *>())
181     DD = PTMD.get<const DeclaratorDecl *>();
182   else
183     DD = PTMD.get<const PointerToMemberData *>()->getDeclaratorDecl();
184 
185   return DD;
186 }
187 
188 //===----------------------------------------------------------------------===//
189 // Other Iterators.
190 //===----------------------------------------------------------------------===//
191 
192 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
193   return getValue()->begin();
194 }
195 
196 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
197   return getValue()->end();
198 }
199 
200 nonloc::PointerToMember::iterator nonloc::PointerToMember::begin() const {
201   const PTMDataType PTMD = getPTMData();
202   if (PTMD.is<const DeclaratorDecl *>())
203     return {};
204   return PTMD.get<const PointerToMemberData *>()->begin();
205 }
206 
207 nonloc::PointerToMember::iterator nonloc::PointerToMember::end() const {
208   const PTMDataType PTMD = getPTMData();
209   if (PTMD.is<const DeclaratorDecl *>())
210     return {};
211   return PTMD.get<const PointerToMemberData *>()->end();
212 }
213 
214 //===----------------------------------------------------------------------===//
215 // Useful predicates.
216 //===----------------------------------------------------------------------===//
217 
218 bool SVal::isConstant() const {
219   return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
220 }
221 
222 bool SVal::isConstant(int I) const {
223   if (Optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
224     return LV->getValue() == I;
225   if (Optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
226     return NV->getValue() == I;
227   return false;
228 }
229 
230 bool SVal::isZeroConstant() const {
231   return isConstant(0);
232 }
233 
234 //===----------------------------------------------------------------------===//
235 // Transfer function dispatch for Non-Locs.
236 //===----------------------------------------------------------------------===//
237 
238 SVal nonloc::ConcreteInt::evalBinOp(SValBuilder &svalBuilder,
239                                     BinaryOperator::Opcode Op,
240                                     const nonloc::ConcreteInt& R) const {
241   const llvm::APSInt* X =
242     svalBuilder.getBasicValueFactory().evalAPSInt(Op, getValue(), R.getValue());
243 
244   if (X)
245     return nonloc::ConcreteInt(*X);
246   else
247     return UndefinedVal();
248 }
249 
250 nonloc::ConcreteInt
251 nonloc::ConcreteInt::evalComplement(SValBuilder &svalBuilder) const {
252   return svalBuilder.makeIntVal(~getValue());
253 }
254 
255 nonloc::ConcreteInt
256 nonloc::ConcreteInt::evalMinus(SValBuilder &svalBuilder) const {
257   return svalBuilder.makeIntVal(-getValue());
258 }
259 
260 //===----------------------------------------------------------------------===//
261 // Transfer function dispatch for Locs.
262 //===----------------------------------------------------------------------===//
263 
264 SVal loc::ConcreteInt::evalBinOp(BasicValueFactory& BasicVals,
265                                  BinaryOperator::Opcode Op,
266                                  const loc::ConcreteInt& R) const {
267   assert(BinaryOperator::isComparisonOp(Op) || Op == BO_Sub);
268 
269   const llvm::APSInt *X = BasicVals.evalAPSInt(Op, getValue(), R.getValue());
270 
271   if (X)
272     return nonloc::ConcreteInt(*X);
273   else
274     return UndefinedVal();
275 }
276 
277 //===----------------------------------------------------------------------===//
278 // Pretty-Printing.
279 //===----------------------------------------------------------------------===//
280 
281 LLVM_DUMP_METHOD void SVal::dump() const { dumpToStream(llvm::errs()); }
282 
283 void SVal::dumpToStream(raw_ostream &os) const {
284   switch (getBaseKind()) {
285     case UnknownValKind:
286       os << "Unknown";
287       break;
288     case NonLocKind:
289       castAs<NonLoc>().dumpToStream(os);
290       break;
291     case LocKind:
292       castAs<Loc>().dumpToStream(os);
293       break;
294     case UndefinedValKind:
295       os << "Undefined";
296       break;
297   }
298 }
299 
300 void NonLoc::dumpToStream(raw_ostream &os) const {
301   switch (getSubKind()) {
302     case nonloc::ConcreteIntKind: {
303       const auto &Value = castAs<nonloc::ConcreteInt>().getValue();
304       os << Value << ' ' << (Value.isSigned() ? 'S' : 'U')
305          << Value.getBitWidth() << 'b';
306       break;
307     }
308     case nonloc::SymbolValKind:
309       os << castAs<nonloc::SymbolVal>().getSymbol();
310       break;
311 
312     case nonloc::LocAsIntegerKind: {
313       const nonloc::LocAsInteger& C = castAs<nonloc::LocAsInteger>();
314       os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
315       break;
316     }
317     case nonloc::CompoundValKind: {
318       const nonloc::CompoundVal& C = castAs<nonloc::CompoundVal>();
319       os << "compoundVal{";
320       bool first = true;
321       for (const auto &I : C) {
322         if (first) {
323           os << ' '; first = false;
324         }
325         else
326           os << ", ";
327 
328         I.dumpToStream(os);
329       }
330       os << "}";
331       break;
332     }
333     case nonloc::LazyCompoundValKind: {
334       const nonloc::LazyCompoundVal &C = castAs<nonloc::LazyCompoundVal>();
335       os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
336          << ',' << C.getRegion()
337          << '}';
338       break;
339     }
340     case nonloc::PointerToMemberKind: {
341       os << "pointerToMember{";
342       const nonloc::PointerToMember &CastRes =
343           castAs<nonloc::PointerToMember>();
344       if (CastRes.getDecl())
345         os << "|" << CastRes.getDecl()->getQualifiedNameAsString() << "|";
346       bool first = true;
347       for (const auto &I : CastRes) {
348         if (first) {
349           os << ' '; first = false;
350         }
351         else
352           os << ", ";
353 
354         os << (*I).getType().getAsString();
355       }
356 
357       os << '}';
358       break;
359     }
360     default:
361       assert(false && "Pretty-printed not implemented for this NonLoc.");
362       break;
363   }
364 }
365 
366 void Loc::dumpToStream(raw_ostream &os) const {
367   switch (getSubKind()) {
368     case loc::ConcreteIntKind:
369       os << castAs<loc::ConcreteInt>().getValue().getZExtValue() << " (Loc)";
370       break;
371     case loc::GotoLabelKind:
372       os << "&&" << castAs<loc::GotoLabel>().getLabel()->getName();
373       break;
374     case loc::MemRegionValKind:
375       os << '&' << castAs<loc::MemRegionVal>().getRegion()->getString();
376       break;
377     default:
378       llvm_unreachable("Pretty-printing not implemented for this Loc.");
379   }
380 }
381