1 //===-- SVals.cpp - Abstract RValues for Path-Sens. Value Tracking --------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines SVal, Loc, and NonLoc, classes that represent
10 // abstract r-values for use with path-sensitive value tracking.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
15 #include "clang/AST/ASTContext.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/JsonSupport.h"
21 #include "clang/Basic/LLVM.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/SValVisitor.h"
26 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
27 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
28 #include "llvm/Support/Compiler.h"
29 #include "llvm/Support/ErrorHandling.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include <cassert>
32 #include <optional>
33
34 using namespace clang;
35 using namespace ento;
36
37 //===----------------------------------------------------------------------===//
38 // Symbol iteration within an SVal.
39 //===----------------------------------------------------------------------===//
40
41 //===----------------------------------------------------------------------===//
42 // Utility methods.
43 //===----------------------------------------------------------------------===//
44
getAsFunctionDecl() const45 const FunctionDecl *SVal::getAsFunctionDecl() const {
46 if (std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>()) {
47 const MemRegion* R = X->getRegion();
48 if (const FunctionCodeRegion *CTR = R->getAs<FunctionCodeRegion>())
49 if (const auto *FD = dyn_cast<FunctionDecl>(CTR->getDecl()))
50 return FD;
51 }
52
53 if (auto X = getAs<nonloc::PointerToMember>()) {
54 if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(X->getDecl()))
55 return MD;
56 }
57 return nullptr;
58 }
59
60 /// If this SVal is a location (subclasses Loc) and wraps a symbol,
61 /// return that SymbolRef. Otherwise return 0.
62 ///
63 /// Implicit casts (ex: void* -> char*) can turn Symbolic region into Element
64 /// region. If that is the case, gets the underlining region.
65 /// When IncludeBaseRegions is set to true and the SubRegion is non-symbolic,
66 /// the first symbolic parent region is returned.
getAsLocSymbol(bool IncludeBaseRegions) const67 SymbolRef SVal::getAsLocSymbol(bool IncludeBaseRegions) const {
68 // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
69 if (const MemRegion *R = getAsRegion())
70 if (const SymbolicRegion *SymR =
71 IncludeBaseRegions ? R->getSymbolicBase()
72 : dyn_cast<SymbolicRegion>(R->StripCasts()))
73 return SymR->getSymbol();
74
75 return nullptr;
76 }
77
78 /// Get the symbol in the SVal or its base region.
getLocSymbolInBase() const79 SymbolRef SVal::getLocSymbolInBase() const {
80 std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>();
81
82 if (!X)
83 return nullptr;
84
85 const MemRegion *R = X->getRegion();
86
87 while (const auto *SR = dyn_cast<SubRegion>(R)) {
88 if (const auto *SymR = dyn_cast<SymbolicRegion>(SR))
89 return SymR->getSymbol();
90 else
91 R = SR->getSuperRegion();
92 }
93
94 return nullptr;
95 }
96
97 /// If this SVal wraps a symbol return that SymbolRef.
98 /// Otherwise, return 0.
99 ///
100 /// Casts are ignored during lookup.
101 /// \param IncludeBaseRegions The boolean that controls whether the search
102 /// should continue to the base regions if the region is not symbolic.
getAsSymbol(bool IncludeBaseRegions) const103 SymbolRef SVal::getAsSymbol(bool IncludeBaseRegions) const {
104 // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
105 if (std::optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
106 return X->getSymbol();
107
108 return getAsLocSymbol(IncludeBaseRegions);
109 }
110
getAsInteger() const111 const llvm::APSInt *SVal::getAsInteger() const {
112 if (auto CI = getAs<nonloc::ConcreteInt>())
113 return CI->getValue().get();
114 if (auto CI = getAs<loc::ConcreteInt>())
115 return CI->getValue().get();
116 return nullptr;
117 }
118
getAsRegion() const119 const MemRegion *SVal::getAsRegion() const {
120 if (std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>())
121 return X->getRegion();
122
123 if (std::optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
124 return X->getLoc().getAsRegion();
125
126 return nullptr;
127 }
128
129 namespace {
130 class TypeRetrievingVisitor
131 : public FullSValVisitor<TypeRetrievingVisitor, QualType> {
132 private:
133 const ASTContext &Context;
134
135 public:
TypeRetrievingVisitor(const ASTContext & Context)136 TypeRetrievingVisitor(const ASTContext &Context) : Context(Context) {}
137
VisitMemRegionVal(loc::MemRegionVal MRV)138 QualType VisitMemRegionVal(loc::MemRegionVal MRV) {
139 return Visit(MRV.getRegion());
140 }
VisitGotoLabel(loc::GotoLabel GL)141 QualType VisitGotoLabel(loc::GotoLabel GL) {
142 return QualType{Context.VoidPtrTy};
143 }
VisitConcreteInt(ConcreteInt CI)144 template <class ConcreteInt> QualType VisitConcreteInt(ConcreteInt CI) {
145 const llvm::APSInt &Value = CI.getValue();
146 if (1 == Value.getBitWidth())
147 return Context.BoolTy;
148 return Context.getIntTypeForBitwidth(Value.getBitWidth(), Value.isSigned());
149 }
VisitLocAsInteger(nonloc::LocAsInteger LI)150 QualType VisitLocAsInteger(nonloc::LocAsInteger LI) {
151 QualType NestedType = Visit(LI.getLoc());
152 if (NestedType.isNull())
153 return NestedType;
154
155 return Context.getIntTypeForBitwidth(LI.getNumBits(),
156 NestedType->isSignedIntegerType());
157 }
VisitCompoundVal(nonloc::CompoundVal CV)158 QualType VisitCompoundVal(nonloc::CompoundVal CV) {
159 return CV.getValue()->getType();
160 }
VisitLazyCompoundVal(nonloc::LazyCompoundVal LCV)161 QualType VisitLazyCompoundVal(nonloc::LazyCompoundVal LCV) {
162 return LCV.getRegion()->getValueType();
163 }
VisitSymbolVal(nonloc::SymbolVal SV)164 QualType VisitSymbolVal(nonloc::SymbolVal SV) {
165 return Visit(SV.getSymbol());
166 }
VisitSymbolicRegion(const SymbolicRegion * SR)167 QualType VisitSymbolicRegion(const SymbolicRegion *SR) {
168 return Visit(SR->getSymbol());
169 }
VisitAllocaRegion(const AllocaRegion *)170 QualType VisitAllocaRegion(const AllocaRegion *) {
171 return QualType{Context.VoidPtrTy};
172 }
VisitTypedRegion(const TypedRegion * TR)173 QualType VisitTypedRegion(const TypedRegion *TR) {
174 return TR->getLocationType();
175 }
VisitSymExpr(const SymExpr * SE)176 QualType VisitSymExpr(const SymExpr *SE) { return SE->getType(); }
177 };
178 } // end anonymous namespace
179
getType(const ASTContext & Context) const180 QualType SVal::getType(const ASTContext &Context) const {
181 TypeRetrievingVisitor TRV{Context};
182 return TRV.Visit(*this);
183 }
184
stripCasts(bool StripBaseCasts) const185 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
186 return getRegion()->StripCasts(StripBaseCasts);
187 }
188
getStore() const189 const void *nonloc::LazyCompoundVal::getStore() const {
190 return static_cast<const LazyCompoundValData*>(Data)->getStore();
191 }
192
getRegion() const193 const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
194 return static_cast<const LazyCompoundValData*>(Data)->getRegion();
195 }
196
isNullMemberPointer() const197 bool nonloc::PointerToMember::isNullMemberPointer() const {
198 return getPTMData().isNull();
199 }
200
getDecl() const201 const NamedDecl *nonloc::PointerToMember::getDecl() const {
202 const auto PTMD = this->getPTMData();
203 if (PTMD.isNull())
204 return nullptr;
205
206 const NamedDecl *ND = nullptr;
207 if (const auto *NDP = dyn_cast<const NamedDecl *>(PTMD))
208 ND = NDP;
209 else
210 ND = cast<const PointerToMemberData *>(PTMD)->getDeclaratorDecl();
211
212 return ND;
213 }
214
215 //===----------------------------------------------------------------------===//
216 // Other Iterators.
217 //===----------------------------------------------------------------------===//
218
begin() const219 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
220 return getValue()->begin();
221 }
222
end() const223 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
224 return getValue()->end();
225 }
226
begin() const227 nonloc::PointerToMember::iterator nonloc::PointerToMember::begin() const {
228 const PTMDataType PTMD = getPTMData();
229 if (isa<const NamedDecl *>(PTMD))
230 return {};
231 return cast<const PointerToMemberData *>(PTMD)->begin();
232 }
233
end() const234 nonloc::PointerToMember::iterator nonloc::PointerToMember::end() const {
235 const PTMDataType PTMD = getPTMData();
236 if (isa<const NamedDecl *>(PTMD))
237 return {};
238 return cast<const PointerToMemberData *>(PTMD)->end();
239 }
240
241 //===----------------------------------------------------------------------===//
242 // Useful predicates.
243 //===----------------------------------------------------------------------===//
244
isConstant() const245 bool SVal::isConstant() const {
246 return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
247 }
248
isConstant(int I) const249 bool SVal::isConstant(int I) const {
250 if (std::optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
251 return *LV->getValue() == I;
252 if (std::optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
253 return *NV->getValue() == I;
254 return false;
255 }
256
isZeroConstant() const257 bool SVal::isZeroConstant() const {
258 return isConstant(0);
259 }
260
261 //===----------------------------------------------------------------------===//
262 // Pretty-Printing.
263 //===----------------------------------------------------------------------===//
264
getKindStr() const265 StringRef SVal::getKindStr() const {
266 switch (getKind()) {
267 #define BASIC_SVAL(Id, Parent) \
268 case Id##Kind: \
269 return #Id;
270 #define LOC_SVAL(Id, Parent) \
271 case Loc##Id##Kind: \
272 return #Id;
273 #define NONLOC_SVAL(Id, Parent) \
274 case NonLoc##Id##Kind: \
275 return #Id;
276 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.def"
277 #undef REGION
278 }
279 llvm_unreachable("Unkown kind!");
280 }
281
dump() const282 LLVM_DUMP_METHOD void SVal::dump() const { dumpToStream(llvm::errs()); }
283
printJson(raw_ostream & Out,bool AddQuotes) const284 void SVal::printJson(raw_ostream &Out, bool AddQuotes) const {
285 std::string Buf;
286 llvm::raw_string_ostream TempOut(Buf);
287
288 dumpToStream(TempOut);
289
290 Out << JsonFormat(Buf, AddQuotes);
291 }
292
dumpToStream(raw_ostream & os) const293 void SVal::dumpToStream(raw_ostream &os) const {
294 if (isUndef()) {
295 os << "Undefined";
296 return;
297 }
298 if (isUnknown()) {
299 os << "Unknown";
300 return;
301 }
302 if (NonLoc::classof(*this)) {
303 castAs<NonLoc>().dumpToStream(os);
304 return;
305 }
306 if (Loc::classof(*this)) {
307 castAs<Loc>().dumpToStream(os);
308 return;
309 }
310 llvm_unreachable("Unhandled SVal kind!");
311 }
312
dumpToStream(raw_ostream & os) const313 void NonLoc::dumpToStream(raw_ostream &os) const {
314 switch (getKind()) {
315 case nonloc::ConcreteIntKind: {
316 APSIntPtr Value = castAs<nonloc::ConcreteInt>().getValue();
317 os << Value << ' ' << (Value->isSigned() ? 'S' : 'U')
318 << Value->getBitWidth() << 'b';
319 break;
320 }
321 case nonloc::SymbolValKind:
322 os << castAs<nonloc::SymbolVal>().getSymbol();
323 break;
324
325 case nonloc::LocAsIntegerKind: {
326 const nonloc::LocAsInteger& C = castAs<nonloc::LocAsInteger>();
327 os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
328 break;
329 }
330 case nonloc::CompoundValKind: {
331 const nonloc::CompoundVal& C = castAs<nonloc::CompoundVal>();
332 os << "compoundVal{";
333 bool first = true;
334 for (const auto &I : C) {
335 if (first) {
336 os << ' '; first = false;
337 }
338 else
339 os << ", ";
340
341 I.dumpToStream(os);
342 }
343 os << "}";
344 break;
345 }
346 case nonloc::LazyCompoundValKind: {
347 const nonloc::LazyCompoundVal &C = castAs<nonloc::LazyCompoundVal>();
348 os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
349 << ',' << C.getRegion()
350 << '}';
351 break;
352 }
353 case nonloc::PointerToMemberKind: {
354 os << "pointerToMember{";
355 const nonloc::PointerToMember &CastRes =
356 castAs<nonloc::PointerToMember>();
357 if (CastRes.getDecl())
358 os << "|" << CastRes.getDecl()->getQualifiedNameAsString() << "|";
359 bool first = true;
360 for (const auto &I : CastRes) {
361 if (first) {
362 os << ' '; first = false;
363 }
364 else
365 os << ", ";
366
367 os << I->getType();
368 }
369
370 os << '}';
371 break;
372 }
373 default:
374 assert(false && "Pretty-printed not implemented for this NonLoc.");
375 break;
376 }
377 }
378
dumpToStream(raw_ostream & os) const379 void Loc::dumpToStream(raw_ostream &os) const {
380 switch (getKind()) {
381 case loc::ConcreteIntKind:
382 os << castAs<loc::ConcreteInt>().getValue()->getZExtValue() << " (Loc)";
383 break;
384 case loc::GotoLabelKind:
385 os << "&&" << castAs<loc::GotoLabel>().getLabel()->getName();
386 break;
387 case loc::MemRegionValKind:
388 os << '&' << castAs<loc::MemRegionVal>().getRegion()->getString();
389 break;
390 default:
391 llvm_unreachable("Pretty-printing not implemented for this Loc.");
392 }
393 }
394