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
hasConjuredSymbol() const44 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
getAsFunctionDecl() const63 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.
getAsLocSymbol(bool IncludeBaseRegions) const85 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.
getLocSymbolInBase() const101 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.
getAsSymbol(bool IncludeBaseRegions) const127 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.
getAsSymbolicExpression() const137 const SymExpr *SVal::getAsSymbolicExpression() const {
138 if (Optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
139 return X->getSymbol();
140
141 return getAsSymbol();
142 }
143
getAsSymExpr() const144 const SymExpr* SVal::getAsSymExpr() const {
145 const SymExpr* Sym = getAsSymbol();
146 if (!Sym)
147 Sym = getAsSymbolicExpression();
148 return Sym;
149 }
150
getAsRegion() const151 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
stripCasts(bool StripBaseCasts) const161 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
162 const MemRegion *R = getRegion();
163 return R ? R->StripCasts(StripBaseCasts) : nullptr;
164 }
165
getStore() const166 const void *nonloc::LazyCompoundVal::getStore() const {
167 return static_cast<const LazyCompoundValData*>(Data)->getStore();
168 }
169
getRegion() const170 const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
171 return static_cast<const LazyCompoundValData*>(Data)->getRegion();
172 }
173
isNullMemberPointer() const174 bool nonloc::PointerToMember::isNullMemberPointer() const {
175 return getPTMData().isNull();
176 }
177
getDecl() const178 const DeclaratorDecl *nonloc::PointerToMember::getDecl() const {
179 const auto PTMD = this->getPTMData();
180 if (PTMD.isNull())
181 return nullptr;
182
183 const DeclaratorDecl *DD = nullptr;
184 if (PTMD.is<const DeclaratorDecl *>())
185 DD = PTMD.get<const DeclaratorDecl *>();
186 else
187 DD = PTMD.get<const PointerToMemberData *>()->getDeclaratorDecl();
188
189 return DD;
190 }
191
192 //===----------------------------------------------------------------------===//
193 // Other Iterators.
194 //===----------------------------------------------------------------------===//
195
begin() const196 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
197 return getValue()->begin();
198 }
199
end() const200 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
201 return getValue()->end();
202 }
203
begin() const204 nonloc::PointerToMember::iterator nonloc::PointerToMember::begin() const {
205 const PTMDataType PTMD = getPTMData();
206 if (PTMD.is<const DeclaratorDecl *>())
207 return {};
208 return PTMD.get<const PointerToMemberData *>()->begin();
209 }
210
end() const211 nonloc::PointerToMember::iterator nonloc::PointerToMember::end() const {
212 const PTMDataType PTMD = getPTMData();
213 if (PTMD.is<const DeclaratorDecl *>())
214 return {};
215 return PTMD.get<const PointerToMemberData *>()->end();
216 }
217
218 //===----------------------------------------------------------------------===//
219 // Useful predicates.
220 //===----------------------------------------------------------------------===//
221
isConstant() const222 bool SVal::isConstant() const {
223 return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
224 }
225
isConstant(int I) const226 bool SVal::isConstant(int I) const {
227 if (Optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
228 return LV->getValue() == I;
229 if (Optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
230 return NV->getValue() == I;
231 return false;
232 }
233
isZeroConstant() const234 bool SVal::isZeroConstant() const {
235 return isConstant(0);
236 }
237
238 //===----------------------------------------------------------------------===//
239 // Transfer function dispatch for Non-Locs.
240 //===----------------------------------------------------------------------===//
241
evalBinOp(SValBuilder & svalBuilder,BinaryOperator::Opcode Op,const nonloc::ConcreteInt & R) const242 SVal nonloc::ConcreteInt::evalBinOp(SValBuilder &svalBuilder,
243 BinaryOperator::Opcode Op,
244 const nonloc::ConcreteInt& R) const {
245 const llvm::APSInt* X =
246 svalBuilder.getBasicValueFactory().evalAPSInt(Op, getValue(), R.getValue());
247
248 if (X)
249 return nonloc::ConcreteInt(*X);
250 else
251 return UndefinedVal();
252 }
253
254 nonloc::ConcreteInt
evalComplement(SValBuilder & svalBuilder) const255 nonloc::ConcreteInt::evalComplement(SValBuilder &svalBuilder) const {
256 return svalBuilder.makeIntVal(~getValue());
257 }
258
259 nonloc::ConcreteInt
evalMinus(SValBuilder & svalBuilder) const260 nonloc::ConcreteInt::evalMinus(SValBuilder &svalBuilder) const {
261 return svalBuilder.makeIntVal(-getValue());
262 }
263
264 //===----------------------------------------------------------------------===//
265 // Transfer function dispatch for Locs.
266 //===----------------------------------------------------------------------===//
267
evalBinOp(BasicValueFactory & BasicVals,BinaryOperator::Opcode Op,const loc::ConcreteInt & R) const268 SVal loc::ConcreteInt::evalBinOp(BasicValueFactory& BasicVals,
269 BinaryOperator::Opcode Op,
270 const loc::ConcreteInt& R) const {
271 assert(BinaryOperator::isComparisonOp(Op) || Op == BO_Sub);
272
273 const llvm::APSInt *X = BasicVals.evalAPSInt(Op, getValue(), R.getValue());
274
275 if (X)
276 return nonloc::ConcreteInt(*X);
277 else
278 return UndefinedVal();
279 }
280
281 //===----------------------------------------------------------------------===//
282 // Pretty-Printing.
283 //===----------------------------------------------------------------------===//
284
dump() const285 LLVM_DUMP_METHOD void SVal::dump() const { dumpToStream(llvm::errs()); }
286
dumpToStream(raw_ostream & os) const287 void SVal::dumpToStream(raw_ostream &os) const {
288 switch (getBaseKind()) {
289 case UnknownValKind:
290 os << "Unknown";
291 break;
292 case NonLocKind:
293 castAs<NonLoc>().dumpToStream(os);
294 break;
295 case LocKind:
296 castAs<Loc>().dumpToStream(os);
297 break;
298 case UndefinedValKind:
299 os << "Undefined";
300 break;
301 }
302 }
303
dumpToStream(raw_ostream & os) const304 void NonLoc::dumpToStream(raw_ostream &os) const {
305 switch (getSubKind()) {
306 case nonloc::ConcreteIntKind: {
307 const auto &Value = castAs<nonloc::ConcreteInt>().getValue();
308 os << Value << ' ' << (Value.isSigned() ? 'S' : 'U')
309 << Value.getBitWidth() << 'b';
310 break;
311 }
312 case nonloc::SymbolValKind:
313 os << castAs<nonloc::SymbolVal>().getSymbol();
314 break;
315
316 case nonloc::LocAsIntegerKind: {
317 const nonloc::LocAsInteger& C = castAs<nonloc::LocAsInteger>();
318 os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
319 break;
320 }
321 case nonloc::CompoundValKind: {
322 const nonloc::CompoundVal& C = castAs<nonloc::CompoundVal>();
323 os << "compoundVal{";
324 bool first = true;
325 for (const auto &I : C) {
326 if (first) {
327 os << ' '; first = false;
328 }
329 else
330 os << ", ";
331
332 I.dumpToStream(os);
333 }
334 os << "}";
335 break;
336 }
337 case nonloc::LazyCompoundValKind: {
338 const nonloc::LazyCompoundVal &C = castAs<nonloc::LazyCompoundVal>();
339 os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
340 << ',' << C.getRegion()
341 << '}';
342 break;
343 }
344 case nonloc::PointerToMemberKind: {
345 os << "pointerToMember{";
346 const nonloc::PointerToMember &CastRes =
347 castAs<nonloc::PointerToMember>();
348 if (CastRes.getDecl())
349 os << "|" << CastRes.getDecl()->getQualifiedNameAsString() << "|";
350 bool first = true;
351 for (const auto &I : CastRes) {
352 if (first) {
353 os << ' '; first = false;
354 }
355 else
356 os << ", ";
357
358 os << (*I).getType().getAsString();
359 }
360
361 os << '}';
362 break;
363 }
364 default:
365 assert(false && "Pretty-printed not implemented for this NonLoc.");
366 break;
367 }
368 }
369
dumpToStream(raw_ostream & os) const370 void Loc::dumpToStream(raw_ostream &os) const {
371 switch (getSubKind()) {
372 case loc::ConcreteIntKind:
373 os << castAs<loc::ConcreteInt>().getValue().getZExtValue() << " (Loc)";
374 break;
375 case loc::GotoLabelKind:
376 os << "&&" << castAs<loc::GotoLabel>().getLabel()->getName();
377 break;
378 case loc::MemRegionValKind:
379 os << '&' << castAs<loc::MemRegionVal>().getRegion()->getString();
380 break;
381 default:
382 llvm_unreachable("Pretty-printing not implemented for this Loc.");
383 }
384 }
385