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/Casting.h"
29 #include "llvm/Support/Compiler.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include <cassert>
33 #include <optional>
34
35 using namespace clang;
36 using namespace ento;
37
38 //===----------------------------------------------------------------------===//
39 // Symbol iteration within an SVal.
40 //===----------------------------------------------------------------------===//
41
42 //===----------------------------------------------------------------------===//
43 // Utility methods.
44 //===----------------------------------------------------------------------===//
45
getAsFunctionDecl() const46 const FunctionDecl *SVal::getAsFunctionDecl() const {
47 if (std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>()) {
48 const MemRegion* R = X->getRegion();
49 if (const FunctionCodeRegion *CTR = R->getAs<FunctionCodeRegion>())
50 if (const auto *FD = dyn_cast<FunctionDecl>(CTR->getDecl()))
51 return FD;
52 }
53
54 if (auto X = getAs<nonloc::PointerToMember>()) {
55 if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(X->getDecl()))
56 return MD;
57 }
58 return nullptr;
59 }
60
61 /// 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.
66 /// When IncludeBaseRegions is set to true and the SubRegion is non-symbolic,
67 /// the first symbolic parent region is returned.
getAsLocSymbol(bool IncludeBaseRegions) const68 SymbolRef SVal::getAsLocSymbol(bool IncludeBaseRegions) const {
69 // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
70 if (const MemRegion *R = getAsRegion())
71 if (const SymbolicRegion *SymR =
72 IncludeBaseRegions ? R->getSymbolicBase()
73 : dyn_cast<SymbolicRegion>(R->StripCasts()))
74 return SymR->getSymbol();
75
76 return nullptr;
77 }
78
79 /// Get the symbol in the SVal or its base region.
getLocSymbolInBase() const80 SymbolRef SVal::getLocSymbolInBase() const {
81 std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>();
82
83 if (!X)
84 return nullptr;
85
86 const MemRegion *R = X->getRegion();
87
88 while (const auto *SR = dyn_cast<SubRegion>(R)) {
89 if (const auto *SymR = dyn_cast<SymbolicRegion>(SR))
90 return SymR->getSymbol();
91 else
92 R = SR->getSuperRegion();
93 }
94
95 return nullptr;
96 }
97
98 /// If this SVal wraps a symbol return that SymbolRef.
99 /// Otherwise, return 0.
100 ///
101 /// Casts are ignored during lookup.
102 /// \param IncludeBaseRegions The boolean that controls whether the search
103 /// should continue to the base regions if the region is not symbolic.
getAsSymbol(bool IncludeBaseRegions) const104 SymbolRef SVal::getAsSymbol(bool IncludeBaseRegions) const {
105 // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
106 if (std::optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
107 return X->getSymbol();
108
109 return getAsLocSymbol(IncludeBaseRegions);
110 }
111
getAsInteger() const112 const llvm::APSInt *SVal::getAsInteger() const {
113 if (auto CI = getAs<nonloc::ConcreteInt>())
114 return &CI->getValue();
115 if (auto CI = getAs<loc::ConcreteInt>())
116 return &CI->getValue();
117 return nullptr;
118 }
119
getAsRegion() const120 const MemRegion *SVal::getAsRegion() const {
121 if (std::optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>())
122 return X->getRegion();
123
124 if (std::optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
125 return X->getLoc().getAsRegion();
126
127 return nullptr;
128 }
129
130 namespace {
131 class TypeRetrievingVisitor
132 : public FullSValVisitor<TypeRetrievingVisitor, QualType> {
133 private:
134 const ASTContext &Context;
135
136 public:
TypeRetrievingVisitor(const ASTContext & Context)137 TypeRetrievingVisitor(const ASTContext &Context) : Context(Context) {}
138
VisitMemRegionVal(loc::MemRegionVal MRV)139 QualType VisitMemRegionVal(loc::MemRegionVal MRV) {
140 return Visit(MRV.getRegion());
141 }
VisitGotoLabel(loc::GotoLabel GL)142 QualType VisitGotoLabel(loc::GotoLabel GL) {
143 return QualType{Context.VoidPtrTy};
144 }
VisitConcreteInt(ConcreteInt CI)145 template <class ConcreteInt> QualType VisitConcreteInt(ConcreteInt CI) {
146 const llvm::APSInt &Value = CI.getValue();
147 if (1 == Value.getBitWidth())
148 return Context.BoolTy;
149 return Context.getIntTypeForBitwidth(Value.getBitWidth(), Value.isSigned());
150 }
VisitLocAsInteger(nonloc::LocAsInteger LI)151 QualType VisitLocAsInteger(nonloc::LocAsInteger LI) {
152 QualType NestedType = Visit(LI.getLoc());
153 if (NestedType.isNull())
154 return NestedType;
155
156 return Context.getIntTypeForBitwidth(LI.getNumBits(),
157 NestedType->isSignedIntegerType());
158 }
VisitCompoundVal(nonloc::CompoundVal CV)159 QualType VisitCompoundVal(nonloc::CompoundVal CV) {
160 return CV.getValue()->getType();
161 }
VisitLazyCompoundVal(nonloc::LazyCompoundVal LCV)162 QualType VisitLazyCompoundVal(nonloc::LazyCompoundVal LCV) {
163 return LCV.getRegion()->getValueType();
164 }
VisitSymbolVal(nonloc::SymbolVal SV)165 QualType VisitSymbolVal(nonloc::SymbolVal SV) {
166 return Visit(SV.getSymbol());
167 }
VisitSymbolicRegion(const SymbolicRegion * SR)168 QualType VisitSymbolicRegion(const SymbolicRegion *SR) {
169 return Visit(SR->getSymbol());
170 }
VisitAllocaRegion(const AllocaRegion *)171 QualType VisitAllocaRegion(const AllocaRegion *) {
172 return QualType{Context.VoidPtrTy};
173 }
VisitTypedRegion(const TypedRegion * TR)174 QualType VisitTypedRegion(const TypedRegion *TR) {
175 return TR->getLocationType();
176 }
VisitSymExpr(const SymExpr * SE)177 QualType VisitSymExpr(const SymExpr *SE) { return SE->getType(); }
178 };
179 } // end anonymous namespace
180
getType(const ASTContext & Context) const181 QualType SVal::getType(const ASTContext &Context) const {
182 TypeRetrievingVisitor TRV{Context};
183 return TRV.Visit(*this);
184 }
185
stripCasts(bool StripBaseCasts) const186 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
187 return getRegion()->StripCasts(StripBaseCasts);
188 }
189
getStore() const190 const void *nonloc::LazyCompoundVal::getStore() const {
191 return static_cast<const LazyCompoundValData*>(Data)->getStore();
192 }
193
getRegion() const194 const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
195 return static_cast<const LazyCompoundValData*>(Data)->getRegion();
196 }
197
isNullMemberPointer() const198 bool nonloc::PointerToMember::isNullMemberPointer() const {
199 return getPTMData().isNull();
200 }
201
getDecl() const202 const NamedDecl *nonloc::PointerToMember::getDecl() const {
203 const auto PTMD = this->getPTMData();
204 if (PTMD.isNull())
205 return nullptr;
206
207 const NamedDecl *ND = nullptr;
208 if (PTMD.is<const NamedDecl *>())
209 ND = PTMD.get<const NamedDecl *>();
210 else
211 ND = PTMD.get<const PointerToMemberData *>()->getDeclaratorDecl();
212
213 return ND;
214 }
215
216 //===----------------------------------------------------------------------===//
217 // Other Iterators.
218 //===----------------------------------------------------------------------===//
219
begin() const220 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
221 return getValue()->begin();
222 }
223
end() const224 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
225 return getValue()->end();
226 }
227
begin() const228 nonloc::PointerToMember::iterator nonloc::PointerToMember::begin() const {
229 const PTMDataType PTMD = getPTMData();
230 if (PTMD.is<const NamedDecl *>())
231 return {};
232 return PTMD.get<const PointerToMemberData *>()->begin();
233 }
234
end() const235 nonloc::PointerToMember::iterator nonloc::PointerToMember::end() const {
236 const PTMDataType PTMD = getPTMData();
237 if (PTMD.is<const NamedDecl *>())
238 return {};
239 return PTMD.get<const PointerToMemberData *>()->end();
240 }
241
242 //===----------------------------------------------------------------------===//
243 // Useful predicates.
244 //===----------------------------------------------------------------------===//
245
isConstant() const246 bool SVal::isConstant() const {
247 return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
248 }
249
isConstant(int I) const250 bool SVal::isConstant(int I) const {
251 if (std::optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
252 return LV->getValue() == I;
253 if (std::optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
254 return NV->getValue() == I;
255 return false;
256 }
257
isZeroConstant() const258 bool SVal::isZeroConstant() const {
259 return isConstant(0);
260 }
261
262 //===----------------------------------------------------------------------===//
263 // Pretty-Printing.
264 //===----------------------------------------------------------------------===//
265
dump() const266 LLVM_DUMP_METHOD void SVal::dump() const { dumpToStream(llvm::errs()); }
267
printJson(raw_ostream & Out,bool AddQuotes) const268 void SVal::printJson(raw_ostream &Out, bool AddQuotes) const {
269 std::string Buf;
270 llvm::raw_string_ostream TempOut(Buf);
271
272 dumpToStream(TempOut);
273
274 Out << JsonFormat(Buf, AddQuotes);
275 }
276
dumpToStream(raw_ostream & os) const277 void SVal::dumpToStream(raw_ostream &os) const {
278 if (isUndef()) {
279 os << "Undefined";
280 return;
281 }
282 if (isUnknown()) {
283 os << "Unknown";
284 return;
285 }
286 if (NonLoc::classof(*this)) {
287 castAs<NonLoc>().dumpToStream(os);
288 return;
289 }
290 if (Loc::classof(*this)) {
291 castAs<Loc>().dumpToStream(os);
292 return;
293 }
294 llvm_unreachable("Unhandled SVal kind!");
295 }
296
dumpToStream(raw_ostream & os) const297 void NonLoc::dumpToStream(raw_ostream &os) const {
298 switch (getKind()) {
299 case nonloc::ConcreteIntKind: {
300 const auto &Value = castAs<nonloc::ConcreteInt>().getValue();
301 os << Value << ' ' << (Value.isSigned() ? 'S' : 'U') << Value.getBitWidth()
302 << 'b';
303 break;
304 }
305 case nonloc::SymbolValKind:
306 os << castAs<nonloc::SymbolVal>().getSymbol();
307 break;
308
309 case nonloc::LocAsIntegerKind: {
310 const nonloc::LocAsInteger& C = castAs<nonloc::LocAsInteger>();
311 os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
312 break;
313 }
314 case nonloc::CompoundValKind: {
315 const nonloc::CompoundVal& C = castAs<nonloc::CompoundVal>();
316 os << "compoundVal{";
317 bool first = true;
318 for (const auto &I : C) {
319 if (first) {
320 os << ' '; first = false;
321 }
322 else
323 os << ", ";
324
325 I.dumpToStream(os);
326 }
327 os << "}";
328 break;
329 }
330 case nonloc::LazyCompoundValKind: {
331 const nonloc::LazyCompoundVal &C = castAs<nonloc::LazyCompoundVal>();
332 os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
333 << ',' << C.getRegion()
334 << '}';
335 break;
336 }
337 case nonloc::PointerToMemberKind: {
338 os << "pointerToMember{";
339 const nonloc::PointerToMember &CastRes =
340 castAs<nonloc::PointerToMember>();
341 if (CastRes.getDecl())
342 os << "|" << CastRes.getDecl()->getQualifiedNameAsString() << "|";
343 bool first = true;
344 for (const auto &I : CastRes) {
345 if (first) {
346 os << ' '; first = false;
347 }
348 else
349 os << ", ";
350
351 os << I->getType();
352 }
353
354 os << '}';
355 break;
356 }
357 default:
358 assert(false && "Pretty-printed not implemented for this NonLoc.");
359 break;
360 }
361 }
362
dumpToStream(raw_ostream & os) const363 void Loc::dumpToStream(raw_ostream &os) const {
364 switch (getKind()) {
365 case loc::ConcreteIntKind:
366 os << castAs<loc::ConcreteInt>().getValue().getZExtValue() << " (Loc)";
367 break;
368 case loc::GotoLabelKind:
369 os << "&&" << castAs<loc::GotoLabel>().getLabel()->getName();
370 break;
371 case loc::MemRegionValKind:
372 os << '&' << castAs<loc::MemRegionVal>().getRegion()->getString();
373 break;
374 default:
375 llvm_unreachable("Pretty-printing not implemented for this Loc.");
376 }
377 }
378