xref: /freebsd-src/contrib/llvm-project/clang/lib/StaticAnalyzer/Core/SVals.cpp (revision 2eb4d8dc723da3cf7d735a3226ae49da4c8c5dbc) 
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/Decl.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/Type.h"
19 #include "clang/Basic/JsonSupport.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 
44 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 
63 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.
85 SymbolRef SVal::getAsLocSymbol(bool IncludeBaseRegions) const {
86   // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
87   if (const MemRegion *R = getAsRegion())
88     if (const SymbolicRegion *SymR =
89             IncludeBaseRegions ? R->getSymbolicBase()
90                                : dyn_cast<SymbolicRegion>(R->StripCasts()))
91       return SymR->getSymbol();
92 
93   return nullptr;
94 }
95 
96 /// Get the symbol in the SVal or its base region.
97 SymbolRef SVal::getLocSymbolInBase() const {
98   Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>();
99 
100   if (!X)
101     return nullptr;
102 
103   const MemRegion *R = X->getRegion();
104 
105   while (const auto *SR = dyn_cast<SubRegion>(R)) {
106     if (const auto *SymR = dyn_cast<SymbolicRegion>(SR))
107       return SymR->getSymbol();
108     else
109       R = SR->getSuperRegion();
110   }
111 
112   return nullptr;
113 }
114 
115 /// If this SVal wraps a symbol return that SymbolRef.
116 /// Otherwise, return 0.
117 ///
118 /// Casts are ignored during lookup.
119 /// \param IncludeBaseRegions The boolean that controls whether the search
120 /// should continue to the base regions if the region is not symbolic.
121 SymbolRef SVal::getAsSymbol(bool IncludeBaseRegions) const {
122   // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
123   if (Optional<nonloc::SymbolVal> X = getAs<nonloc::SymbolVal>())
124     return X->getSymbol();
125 
126   return getAsLocSymbol(IncludeBaseRegions);
127 }
128 
129 const MemRegion *SVal::getAsRegion() const {
130   if (Optional<loc::MemRegionVal> X = getAs<loc::MemRegionVal>())
131     return X->getRegion();
132 
133   if (Optional<nonloc::LocAsInteger> X = getAs<nonloc::LocAsInteger>())
134     return X->getLoc().getAsRegion();
135 
136   return nullptr;
137 }
138 
139 const MemRegion *loc::MemRegionVal::stripCasts(bool StripBaseCasts) const {
140   const MemRegion *R = getRegion();
141   return R ?  R->StripCasts(StripBaseCasts) : nullptr;
142 }
143 
144 const void *nonloc::LazyCompoundVal::getStore() const {
145   return static_cast<const LazyCompoundValData*>(Data)->getStore();
146 }
147 
148 const TypedValueRegion *nonloc::LazyCompoundVal::getRegion() const {
149   return static_cast<const LazyCompoundValData*>(Data)->getRegion();
150 }
151 
152 bool nonloc::PointerToMember::isNullMemberPointer() const {
153   return getPTMData().isNull();
154 }
155 
156 const NamedDecl *nonloc::PointerToMember::getDecl() const {
157   const auto PTMD = this->getPTMData();
158   if (PTMD.isNull())
159     return nullptr;
160 
161   const NamedDecl *ND = nullptr;
162   if (PTMD.is<const NamedDecl *>())
163     ND = PTMD.get<const NamedDecl *>();
164   else
165     ND = PTMD.get<const PointerToMemberData *>()->getDeclaratorDecl();
166 
167   return ND;
168 }
169 
170 //===----------------------------------------------------------------------===//
171 // Other Iterators.
172 //===----------------------------------------------------------------------===//
173 
174 nonloc::CompoundVal::iterator nonloc::CompoundVal::begin() const {
175   return getValue()->begin();
176 }
177 
178 nonloc::CompoundVal::iterator nonloc::CompoundVal::end() const {
179   return getValue()->end();
180 }
181 
182 nonloc::PointerToMember::iterator nonloc::PointerToMember::begin() const {
183   const PTMDataType PTMD = getPTMData();
184   if (PTMD.is<const NamedDecl *>())
185     return {};
186   return PTMD.get<const PointerToMemberData *>()->begin();
187 }
188 
189 nonloc::PointerToMember::iterator nonloc::PointerToMember::end() const {
190   const PTMDataType PTMD = getPTMData();
191   if (PTMD.is<const NamedDecl *>())
192     return {};
193   return PTMD.get<const PointerToMemberData *>()->end();
194 }
195 
196 //===----------------------------------------------------------------------===//
197 // Useful predicates.
198 //===----------------------------------------------------------------------===//
199 
200 bool SVal::isConstant() const {
201   return getAs<nonloc::ConcreteInt>() || getAs<loc::ConcreteInt>();
202 }
203 
204 bool SVal::isConstant(int I) const {
205   if (Optional<loc::ConcreteInt> LV = getAs<loc::ConcreteInt>())
206     return LV->getValue() == I;
207   if (Optional<nonloc::ConcreteInt> NV = getAs<nonloc::ConcreteInt>())
208     return NV->getValue() == I;
209   return false;
210 }
211 
212 bool SVal::isZeroConstant() const {
213   return isConstant(0);
214 }
215 
216 //===----------------------------------------------------------------------===//
217 // Transfer function dispatch for Non-Locs.
218 //===----------------------------------------------------------------------===//
219 
220 SVal nonloc::ConcreteInt::evalBinOp(SValBuilder &svalBuilder,
221                                     BinaryOperator::Opcode Op,
222                                     const nonloc::ConcreteInt& R) const {
223   const llvm::APSInt* X =
224     svalBuilder.getBasicValueFactory().evalAPSInt(Op, getValue(), R.getValue());
225 
226   if (X)
227     return nonloc::ConcreteInt(*X);
228   else
229     return UndefinedVal();
230 }
231 
232 nonloc::ConcreteInt
233 nonloc::ConcreteInt::evalComplement(SValBuilder &svalBuilder) const {
234   return svalBuilder.makeIntVal(~getValue());
235 }
236 
237 nonloc::ConcreteInt
238 nonloc::ConcreteInt::evalMinus(SValBuilder &svalBuilder) const {
239   return svalBuilder.makeIntVal(-getValue());
240 }
241 
242 //===----------------------------------------------------------------------===//
243 // Transfer function dispatch for Locs.
244 //===----------------------------------------------------------------------===//
245 
246 SVal loc::ConcreteInt::evalBinOp(BasicValueFactory& BasicVals,
247                                  BinaryOperator::Opcode Op,
248                                  const loc::ConcreteInt& R) const {
249   assert(BinaryOperator::isComparisonOp(Op) || Op == BO_Sub);
250 
251   const llvm::APSInt *X = BasicVals.evalAPSInt(Op, getValue(), R.getValue());
252 
253   if (X)
254     return nonloc::ConcreteInt(*X);
255   else
256     return UndefinedVal();
257 }
258 
259 //===----------------------------------------------------------------------===//
260 // Pretty-Printing.
261 //===----------------------------------------------------------------------===//
262 
263 LLVM_DUMP_METHOD void SVal::dump() const { dumpToStream(llvm::errs()); }
264 
265 void SVal::printJson(raw_ostream &Out, bool AddQuotes) const {
266   std::string Buf;
267   llvm::raw_string_ostream TempOut(Buf);
268 
269   dumpToStream(TempOut);
270 
271   Out << JsonFormat(TempOut.str(), AddQuotes);
272 }
273 
274 void SVal::dumpToStream(raw_ostream &os) const {
275   switch (getBaseKind()) {
276     case UnknownValKind:
277       os << "Unknown";
278       break;
279     case NonLocKind:
280       castAs<NonLoc>().dumpToStream(os);
281       break;
282     case LocKind:
283       castAs<Loc>().dumpToStream(os);
284       break;
285     case UndefinedValKind:
286       os << "Undefined";
287       break;
288   }
289 }
290 
291 void NonLoc::dumpToStream(raw_ostream &os) const {
292   switch (getSubKind()) {
293     case nonloc::ConcreteIntKind: {
294       const auto &Value = castAs<nonloc::ConcreteInt>().getValue();
295       os << Value << ' ' << (Value.isSigned() ? 'S' : 'U')
296          << Value.getBitWidth() << 'b';
297       break;
298     }
299     case nonloc::SymbolValKind:
300       os << castAs<nonloc::SymbolVal>().getSymbol();
301       break;
302 
303     case nonloc::LocAsIntegerKind: {
304       const nonloc::LocAsInteger& C = castAs<nonloc::LocAsInteger>();
305       os << C.getLoc() << " [as " << C.getNumBits() << " bit integer]";
306       break;
307     }
308     case nonloc::CompoundValKind: {
309       const nonloc::CompoundVal& C = castAs<nonloc::CompoundVal>();
310       os << "compoundVal{";
311       bool first = true;
312       for (const auto &I : C) {
313         if (first) {
314           os << ' '; first = false;
315         }
316         else
317           os << ", ";
318 
319         I.dumpToStream(os);
320       }
321       os << "}";
322       break;
323     }
324     case nonloc::LazyCompoundValKind: {
325       const nonloc::LazyCompoundVal &C = castAs<nonloc::LazyCompoundVal>();
326       os << "lazyCompoundVal{" << const_cast<void *>(C.getStore())
327          << ',' << C.getRegion()
328          << '}';
329       break;
330     }
331     case nonloc::PointerToMemberKind: {
332       os << "pointerToMember{";
333       const nonloc::PointerToMember &CastRes =
334           castAs<nonloc::PointerToMember>();
335       if (CastRes.getDecl())
336         os << "|" << CastRes.getDecl()->getQualifiedNameAsString() << "|";
337       bool first = true;
338       for (const auto &I : CastRes) {
339         if (first) {
340           os << ' '; first = false;
341         }
342         else
343           os << ", ";
344 
345         os << (*I).getType().getAsString();
346       }
347 
348       os << '}';
349       break;
350     }
351     default:
352       assert(false && "Pretty-printed not implemented for this NonLoc.");
353       break;
354   }
355 }
356 
357 void Loc::dumpToStream(raw_ostream &os) const {
358   switch (getSubKind()) {
359     case loc::ConcreteIntKind:
360       os << castAs<loc::ConcreteInt>().getValue().getZExtValue() << " (Loc)";
361       break;
362     case loc::GotoLabelKind:
363       os << "&&" << castAs<loc::GotoLabel>().getLabel()->getName();
364       break;
365     case loc::MemRegionValKind:
366       os << '&' << castAs<loc::MemRegionVal>().getRegion()->getString();
367       break;
368     default:
369       llvm_unreachable("Pretty-printing not implemented for this Loc.");
370   }
371 }
372