xref: /llvm-project/clang/lib/StaticAnalyzer/Core/SVals.cpp (revision 13e20bcb98e57831d46162b9ba42a78d85e8283d) 
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 
46 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.
68 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.
80 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.
104 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 
112 const llvm::APSInt *SVal::getAsInteger() const {
113   if (auto CI = getAs<nonloc::ConcreteInt>())
114     return CI->getValue().get();
115   if (auto CI = getAs<loc::ConcreteInt>())
116     return CI->getValue().get();
117   return nullptr;
118 }
119 
120 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:
137   TypeRetrievingVisitor(const ASTContext &Context) : Context(Context) {}
138 
139   QualType VisitMemRegionVal(loc::MemRegionVal MRV) {
140     return Visit(MRV.getRegion());
141   }
142   QualType VisitGotoLabel(loc::GotoLabel GL) {
143     return QualType{Context.VoidPtrTy};
144   }
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   }
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   }
159   QualType VisitCompoundVal(nonloc::CompoundVal CV) {
160     return CV.getValue()->getType();
161   }
162   QualType VisitLazyCompoundVal(nonloc::LazyCompoundVal LCV) {
163     return LCV.getRegion()->getValueType();
164   }
165   QualType VisitSymbolVal(nonloc::SymbolVal SV) {
166     return Visit(SV.getSymbol());
167   }
168   QualType VisitSymbolicRegion(const SymbolicRegion *SR) {
169     return Visit(SR->getSymbol());
170   }
171   QualType VisitAllocaRegion(const AllocaRegion *) {
172     return QualType{Context.VoidPtrTy};
173   }
174   QualType VisitTypedRegion(const TypedRegion *TR) {
175     return TR->getLocationType();
176   }
177   QualType VisitSymExpr(const SymExpr *SE) { return SE->getType(); }
178 };
179 } // end anonymous namespace
180 
181 QualType SVal::getType(const ASTContext &Context) const {
182   TypeRetrievingVisitor TRV{Context};
183   return TRV.Visit(*this);
184 }
185 
186 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
187   return getRegion()->StripCasts(StripBaseCasts);
188 }
189 
190 const void *nonloc::LazyCompoundVal::getStore() const {
191   return static_cast<const LazyCompoundValData*>(Data)->getStore();
192 }
193 
194 const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
195   return static_cast<const LazyCompoundValData*>(Data)->getRegion();
196 }
197 
198 bool nonloc::PointerToMember::isNullMemberPointer() const {
199   return getPTMData().isNull();
200 }
201 
202 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 (const auto *NDP = dyn_cast<const NamedDecl *>(PTMD))
209     ND = NDP;
210   else
211     ND = cast<const PointerToMemberData *>(PTMD)->getDeclaratorDecl();
212 
213   return ND;
214 }
215 
216 //===----------------------------------------------------------------------===//
217 // Other Iterators.
218 //===----------------------------------------------------------------------===//
219 
220 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
221   return getValue()->begin();
222 }
223 
224 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
225   return getValue()->end();
226 }
227 
228 nonloc::PointerToMember::iterator nonloc::PointerToMember::begin() const {
229   const PTMDataType PTMD = getPTMData();
230   if (isa<const NamedDecl *>(PTMD))
231     return {};
232   return cast<const PointerToMemberData *>(PTMD)->begin();
233 }
234 
235 nonloc::PointerToMember::iterator nonloc::PointerToMember::end() const {
236   const PTMDataType PTMD = getPTMData();
237   if (isa<const NamedDecl *>(PTMD))
238     return {};
239   return cast<const PointerToMemberData *>(PTMD)->end();
240 }
241 
242 //===----------------------------------------------------------------------===//
243 // Useful predicates.
244 //===----------------------------------------------------------------------===//
245 
246 bool SVal::isConstant() const {
247   return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
248 }
249 
250 bool SVal::isConstant(int I) const {
251   if (std::optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
252     return *LV->getValue().get() == I;
253   if (std::optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
254     return *NV->getValue().get() == I;
255   return false;
256 }
257 
258 bool SVal::isZeroConstant() const {
259   return isConstant(0);
260 }
261 
262 //===----------------------------------------------------------------------===//
263 // Pretty-Printing.
264 //===----------------------------------------------------------------------===//
265 
266 StringRef SVal::getKindStr() const {
267   switch (getKind()) {
268 #define BASIC_SVAL(Id, Parent)                                                 \
269   case Id##Kind:                                                               \
270     return #Id;
271 #define LOC_SVAL(Id, Parent)                                                   \
272   case Loc##Id##Kind:                                                          \
273     return #Id;
274 #define NONLOC_SVAL(Id, Parent)                                                \
275   case NonLoc##Id##Kind:                                                       \
276     return #Id;
277 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.def"
278 #undef REGION
279   }
280   llvm_unreachable("Unkown kind!");
281 }
282 
283 LLVM_DUMP_METHOD void SVal::dump() const { dumpToStream(llvm::errs()); }
284 
285 void SVal::printJson(raw_ostream &Out, bool AddQuotes) const {
286   std::string Buf;
287   llvm::raw_string_ostream TempOut(Buf);
288 
289   dumpToStream(TempOut);
290 
291   Out << JsonFormat(Buf, AddQuotes);
292 }
293 
294 void SVal::dumpToStream(raw_ostream &os) const {
295   if (isUndef()) {
296     os << "Undefined";
297     return;
298   }
299   if (isUnknown()) {
300     os << "Unknown";
301     return;
302   }
303   if (NonLoc::classof(*this)) {
304     castAs<NonLoc>().dumpToStream(os);
305     return;
306   }
307   if (Loc::classof(*this)) {
308     castAs<Loc>().dumpToStream(os);
309     return;
310   }
311   llvm_unreachable("Unhandled SVal kind!");
312 }
313 
314 void NonLoc::dumpToStream(raw_ostream &os) const {
315   switch (getKind()) {
316   case nonloc::ConcreteIntKind: {
317     APSIntPtr Value = castAs<nonloc::ConcreteInt>().getValue();
318     os << Value << ' ' << (Value->isSigned() ? 'S' : 'U')
319        << Value->getBitWidth() << 'b';
320     break;
321   }
322     case nonloc::SymbolValKind:
323       os << castAs<nonloc::SymbolVal>().getSymbol();
324       break;
325 
326     case nonloc::LocAsIntegerKind: {
327       const nonloc::LocAsInteger& C = castAs<nonloc::LocAsInteger>();
328       os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
329       break;
330     }
331     case nonloc::CompoundValKind: {
332       const nonloc::CompoundVal& C = castAs<nonloc::CompoundVal>();
333       os << "compoundVal{";
334       bool first = true;
335       for (const auto &I : C) {
336         if (first) {
337           os << ' '; first = false;
338         }
339         else
340           os << ", ";
341 
342         I.dumpToStream(os);
343       }
344       os << "}";
345       break;
346     }
347     case nonloc::LazyCompoundValKind: {
348       const nonloc::LazyCompoundVal &C = castAs<nonloc::LazyCompoundVal>();
349       os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
350          << ',' << C.getRegion()
351          << '}';
352       break;
353     }
354     case nonloc::PointerToMemberKind: {
355       os << "pointerToMember{";
356       const nonloc::PointerToMember &CastRes =
357           castAs<nonloc::PointerToMember>();
358       if (CastRes.getDecl())
359         os << "|" << CastRes.getDecl()->getQualifiedNameAsString() << "|";
360       bool first = true;
361       for (const auto &I : CastRes) {
362         if (first) {
363           os << ' '; first = false;
364         }
365         else
366           os << ", ";
367 
368         os << I->getType();
369       }
370 
371       os << '}';
372       break;
373     }
374     default:
375       assert(false && "Pretty-printed not implemented for this NonLoc.");
376       break;
377     }
378 }
379 
380 void Loc::dumpToStream(raw_ostream &os) const {
381   switch (getKind()) {
382   case loc::ConcreteIntKind:
383     os << castAs<loc::ConcreteInt>().getValue()->getZExtValue() << " (Loc)";
384     break;
385   case loc::GotoLabelKind:
386     os << "&&" << castAs<loc::GotoLabel>().getLabel()->getName();
387     break;
388   case loc::MemRegionValKind:
389     os << '&' << castAs<loc::MemRegionVal>().getRegion()->getString();
390     break;
391   default:
392     llvm_unreachable("Pretty-printing not implemented for this Loc.");
393   }
394 }
395