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/ADT/Optional.h"
29 #include "llvm/Support/Casting.h"
30 #include "llvm/Support/Compiler.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include <cassert>
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 (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   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 (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();
115   if (auto CI = getAs<loc::ConcreteInt>())
116     return &CI->getValue();
117   return nullptr;
118 }
119 
120 const MemRegion *SVal::getAsRegion() const {
121   if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>())
122     return X->getRegion();
123 
124   if (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 VisitLocMemRegionVal(loc::MemRegionVal MRV) {
140     return Visit(MRV.getRegion());
141   }
142   QualType VisitLocGotoLabel(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 VisitLocConcreteInt(loc::ConcreteInt CI) {
152     return VisitConcreteInt(CI);
153   }
154   QualType VisitNonLocConcreteInt(nonloc::ConcreteInt CI) {
155     return VisitConcreteInt(CI);
156   }
157   QualType VisitNonLocLocAsInteger(nonloc::LocAsInteger LI) {
158     QualType NestedType = Visit(LI.getLoc());
159     if (NestedType.isNull())
160       return NestedType;
161 
162     return Context.getIntTypeForBitwidth(LI.getNumBits(),
163                                          NestedType->isSignedIntegerType());
164   }
165   QualType VisitNonLocCompoundVal(nonloc::CompoundVal CV) {
166     return CV.getValue()->getType();
167   }
168   QualType VisitNonLocLazyCompoundVal(nonloc::LazyCompoundVal LCV) {
169     return LCV.getRegion()->getValueType();
170   }
171   QualType VisitNonLocSymbolVal(nonloc::SymbolVal SV) {
172     return Visit(SV.getSymbol());
173   }
174   QualType VisitSymbolicRegion(const SymbolicRegion *SR) {
175     return Visit(SR->getSymbol());
176   }
177   QualType VisitTypedRegion(const TypedRegion *TR) {
178     return TR->getLocationType();
179   }
180   QualType VisitSymExpr(const SymExpr *SE) { return SE->getType(); }
181 };
182 } // end anonymous namespace
183 
184 QualType SVal::getType(const ASTContext &Context) const {
185   TypeRetrievingVisitor TRV{Context};
186   return TRV.Visit(*this);
187 }
188 
189 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
190   return getRegion()->StripCasts(StripBaseCasts);
191 }
192 
193 const void *nonloc::LazyCompoundVal::getStore() const {
194   return static_cast<const LazyCompoundValData*>(Data)->getStore();
195 }
196 
197 const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
198   return static_cast<const LazyCompoundValData*>(Data)->getRegion();
199 }
200 
201 bool nonloc::PointerToMember::isNullMemberPointer() const {
202   return getPTMData().isNull();
203 }
204 
205 const NamedDecl *nonloc::PointerToMember::getDecl() const {
206   const auto PTMD = this->getPTMData();
207   if (PTMD.isNull())
208     return nullptr;
209 
210   const NamedDecl *ND = nullptr;
211   if (PTMD.is<const NamedDecl *>())
212     ND = PTMD.get<const NamedDecl *>();
213   else
214     ND = PTMD.get<const PointerToMemberData *>()->getDeclaratorDecl();
215 
216   return ND;
217 }
218 
219 //===----------------------------------------------------------------------===//
220 // Other Iterators.
221 //===----------------------------------------------------------------------===//
222 
223 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
224   return getValue()->begin();
225 }
226 
227 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
228   return getValue()->end();
229 }
230 
231 nonloc::PointerToMember::iterator nonloc::PointerToMember::begin() const {
232   const PTMDataType PTMD = getPTMData();
233   if (PTMD.is<const NamedDecl *>())
234     return {};
235   return PTMD.get<const PointerToMemberData *>()->begin();
236 }
237 
238 nonloc::PointerToMember::iterator nonloc::PointerToMember::end() const {
239   const PTMDataType PTMD = getPTMData();
240   if (PTMD.is<const NamedDecl *>())
241     return {};
242   return PTMD.get<const PointerToMemberData *>()->end();
243 }
244 
245 //===----------------------------------------------------------------------===//
246 // Useful predicates.
247 //===----------------------------------------------------------------------===//
248 
249 bool SVal::isConstant() const {
250   return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
251 }
252 
253 bool SVal::isConstant(int I) const {
254   if (Optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
255     return LV->getValue() == I;
256   if (Optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
257     return NV->getValue() == I;
258   return false;
259 }
260 
261 bool SVal::isZeroConstant() const {
262   return isConstant(0);
263 }
264 
265 //===----------------------------------------------------------------------===//
266 // Pretty-Printing.
267 //===----------------------------------------------------------------------===//
268 
269 LLVM_DUMP_METHOD void SVal::dump() const { dumpToStream(llvm::errs()); }
270 
271 void SVal::printJson(raw_ostream &Out, bool AddQuotes) const {
272   std::string Buf;
273   llvm::raw_string_ostream TempOut(Buf);
274 
275   dumpToStream(TempOut);
276 
277   Out << JsonFormat(TempOut.str(), AddQuotes);
278 }
279 
280 void SVal::dumpToStream(raw_ostream &os) const {
281   switch (getBaseKind()) {
282     case UnknownValKind:
283       os << "Unknown";
284       break;
285     case NonLocKind:
286       castAs<NonLoc>().dumpToStream(os);
287       break;
288     case LocKind:
289       castAs<Loc>().dumpToStream(os);
290       break;
291     case UndefinedValKind:
292       os << "Undefined";
293       break;
294   }
295 }
296 
297 void NonLoc::dumpToStream(raw_ostream &os) const {
298   switch (getSubKind()) {
299     case nonloc::ConcreteIntKind: {
300       const auto &Value = castAs<nonloc::ConcreteInt>().getValue();
301       os << Value << ' ' << (Value.isSigned() ? 'S' : 'U')
302          << Value.getBitWidth() << '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 
363 void Loc::dumpToStream(raw_ostream &os) const {
364   switch (getSubKind()) {
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