clang 20.0.0git
SymbolManager.cpp
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1//===- SymbolManager.h - Management of Symbolic Values --------------------===//
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 SymbolManager, a class that manages symbolic values
10// created for use by ExprEngine and related classes.
11//
12//===----------------------------------------------------------------------===//
13
16#include "clang/AST/Expr.h"
17#include "clang/AST/StmtObjC.h"
20#include "clang/Basic/LLVM.h"
25#include "llvm/ADT/FoldingSet.h"
26#include "llvm/ADT/STLExtras.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
33using namespace clang;
34using namespace ento;
35
36void SymExpr::anchor() {}
37
38StringRef SymbolConjured::getKindStr() const { return "conj_$"; }
39StringRef SymbolDerived::getKindStr() const { return "derived_$"; }
40StringRef SymbolExtent::getKindStr() const { return "extent_$"; }
41StringRef SymbolMetadata::getKindStr() const { return "meta_$"; }
42StringRef SymbolRegionValue::getKindStr() const { return "reg_$"; }
43
44LLVM_DUMP_METHOD void SymExpr::dump() const { dumpToStream(llvm::errs()); }
45
46void BinarySymExpr::dumpToStreamImpl(raw_ostream &OS, const SymExpr *Sym) {
47 OS << '(';
48 Sym->dumpToStream(OS);
49 OS << ')';
50}
51
53 const llvm::APSInt &Value) {
54 if (Value.isUnsigned())
55 OS << Value.getZExtValue();
56 else
57 OS << Value.getSExtValue();
58 if (Value.isUnsigned())
59 OS << 'U';
60}
61
64 OS << ' ' << BinaryOperator::getOpcodeStr(Op) << ' ';
65}
66
67void SymbolCast::dumpToStream(raw_ostream &os) const {
68 os << '(' << ToTy << ") (";
69 Operand->dumpToStream(os);
70 os << ')';
71}
72
73void UnarySymExpr::dumpToStream(raw_ostream &os) const {
75 bool Binary = isa<BinarySymExpr>(Operand);
76 if (Binary)
77 os << '(';
78 Operand->dumpToStream(os);
79 if (Binary)
80 os << ')';
81}
82
83void SymbolConjured::dumpToStream(raw_ostream &os) const {
84 os << getKindStr() << getSymbolID() << '{' << T << ", LC" << LCtx->getID();
85 if (S)
86 os << ", S" << S->getID(LCtx->getDecl()->getASTContext());
87 else
88 os << ", no stmt";
89 os << ", #" << Count << '}';
90}
91
92void SymbolDerived::dumpToStream(raw_ostream &os) const {
93 os << getKindStr() << getSymbolID() << '{' << getParentSymbol() << ','
94 << getRegion() << '}';
95}
96
97void SymbolExtent::dumpToStream(raw_ostream &os) const {
98 os << getKindStr() << getSymbolID() << '{' << getRegion() << '}';
99}
100
101void SymbolMetadata::dumpToStream(raw_ostream &os) const {
102 os << getKindStr() << getSymbolID() << '{' << getRegion() << ',' << T << '}';
103}
104
105void SymbolData::anchor() {}
106
107void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
108 os << getKindStr() << getSymbolID() << '<' << getType() << ' ' << R << '>';
109}
110
112 return itr == X.itr;
113}
114
116 return itr != X.itr;
117}
118
120 itr.push_back(SE);
121}
122
124 assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
125 expand();
126 return *this;
127}
128
130 assert(!itr.empty() && "attempting to dereference an 'end' iterator");
131 return itr.back();
132}
133
134void SymExpr::symbol_iterator::expand() {
135 const SymExpr *SE = itr.pop_back_val();
136
137 switch (SE->getKind()) {
138 case SymExpr::SymbolRegionValueKind:
139 case SymExpr::SymbolConjuredKind:
140 case SymExpr::SymbolDerivedKind:
141 case SymExpr::SymbolExtentKind:
142 case SymExpr::SymbolMetadataKind:
143 return;
144 case SymExpr::SymbolCastKind:
145 itr.push_back(cast<SymbolCast>(SE)->getOperand());
146 return;
147 case SymExpr::UnarySymExprKind:
148 itr.push_back(cast<UnarySymExpr>(SE)->getOperand());
149 return;
150 case SymExpr::SymIntExprKind:
151 itr.push_back(cast<SymIntExpr>(SE)->getLHS());
152 return;
153 case SymExpr::IntSymExprKind:
154 itr.push_back(cast<IntSymExpr>(SE)->getRHS());
155 return;
156 case SymExpr::SymSymExprKind: {
157 const auto *x = cast<SymSymExpr>(SE);
158 itr.push_back(x->getLHS());
159 itr.push_back(x->getRHS());
160 return;
161 }
162 }
163 llvm_unreachable("unhandled expansion case");
164}
165
167 return T;
168}
169
171 return R->getValueType();
172}
173
175 ASTContext &Ctx = R->getMemRegionManager().getContext();
176 return Ctx.getSizeType();
177}
178
180 return T;
181}
182
184 return R->getValueType();
185}
186
188 T = T.getCanonicalType();
189
190 if (Loc::isLocType(T))
191 return true;
192
194 return true;
195
196 if (T->isRecordType() && !T->isUnionType())
197 return true;
198
199 return false;
200}
201
203 const SymbolRef Dependent) {
204 auto &dependencies = SymbolDependencies[Primary];
205 if (!dependencies) {
206 dependencies = std::make_unique<SymbolRefSmallVectorTy>();
207 }
208 dependencies->push_back(Dependent);
209}
210
212 const SymbolRef Primary) {
213 SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
214 if (I == SymbolDependencies.end())
215 return nullptr;
216 return I->second.get();
217}
218
219void SymbolReaper::markDependentsLive(SymbolRef sym) {
220 // Do not mark dependents more then once.
221 SymbolMapTy::iterator LI = TheLiving.find(sym);
222 assert(LI != TheLiving.end() && "The primary symbol is not live.");
223 if (LI->second == HaveMarkedDependents)
224 return;
225 LI->second = HaveMarkedDependents;
226
227 if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
228 for (const auto I : *Deps) {
229 if (TheLiving.contains(I))
230 continue;
231 markLive(I);
232 }
233 }
234}
235
237 TheLiving[sym] = NotProcessed;
238 markDependentsLive(sym);
239}
240
242 LiveRegionRoots.insert(region->getBaseRegion());
243 markElementIndicesLive(region);
244}
245
247 LazilyCopiedRegionRoots.insert(region->getBaseRegion());
248}
249
251 for (auto SR = dyn_cast<SubRegion>(region); SR;
252 SR = dyn_cast<SubRegion>(SR->getSuperRegion())) {
253 if (const auto ER = dyn_cast<ElementRegion>(SR)) {
254 SVal Idx = ER->getIndex();
255 for (SymbolRef Sym : Idx.symbols())
256 markLive(Sym);
257 }
258 }
259}
260
262 if (isa<SymbolMetadata>(sym))
263 MetadataInUse.insert(sym);
264}
265
267 // TODO: For now, liveness of a memory region is equivalent to liveness of its
268 // base region. In fact we can do a bit better: say, if a particular FieldDecl
269 // is not used later in the path, we can diagnose a leak of a value within
270 // that field earlier than, say, the variable that contains the field dies.
271 MR = MR->getBaseRegion();
272 if (LiveRegionRoots.count(MR))
273 return true;
274
275 if (const auto *SR = dyn_cast<SymbolicRegion>(MR))
276 return isLive(SR->getSymbol());
277
278 if (const auto *VR = dyn_cast<VarRegion>(MR))
279 return isLive(VR, true);
280
281 // FIXME: This is a gross over-approximation. What we really need is a way to
282 // tell if anything still refers to this region. Unlike SymbolicRegions,
283 // AllocaRegions don't have associated symbols, though, so we don't actually
284 // have a way to track their liveness.
285 return isa<AllocaRegion, CXXThisRegion, MemSpaceRegion, CodeTextRegion>(MR);
286}
287
288bool SymbolReaper::isLazilyCopiedRegion(const MemRegion *MR) const {
289 // TODO: See comment in isLiveRegion.
290 return LazilyCopiedRegionRoots.count(MR->getBaseRegion());
291}
292
293bool SymbolReaper::isReadableRegion(const MemRegion *MR) {
294 return isLiveRegion(MR) || isLazilyCopiedRegion(MR);
295}
296
298 if (TheLiving.count(sym)) {
299 markDependentsLive(sym);
300 return true;
301 }
302
303 bool KnownLive;
304
305 switch (sym->getKind()) {
306 case SymExpr::SymbolRegionValueKind:
307 KnownLive = isReadableRegion(cast<SymbolRegionValue>(sym)->getRegion());
308 break;
309 case SymExpr::SymbolConjuredKind:
310 KnownLive = false;
311 break;
312 case SymExpr::SymbolDerivedKind:
313 KnownLive = isLive(cast<SymbolDerived>(sym)->getParentSymbol());
314 break;
315 case SymExpr::SymbolExtentKind:
316 KnownLive = isLiveRegion(cast<SymbolExtent>(sym)->getRegion());
317 break;
318 case SymExpr::SymbolMetadataKind:
319 KnownLive = MetadataInUse.count(sym) &&
320 isLiveRegion(cast<SymbolMetadata>(sym)->getRegion());
321 if (KnownLive)
322 MetadataInUse.erase(sym);
323 break;
324 case SymExpr::SymIntExprKind:
325 KnownLive = isLive(cast<SymIntExpr>(sym)->getLHS());
326 break;
327 case SymExpr::IntSymExprKind:
328 KnownLive = isLive(cast<IntSymExpr>(sym)->getRHS());
329 break;
330 case SymExpr::SymSymExprKind:
331 KnownLive = isLive(cast<SymSymExpr>(sym)->getLHS()) &&
332 isLive(cast<SymSymExpr>(sym)->getRHS());
333 break;
334 case SymExpr::SymbolCastKind:
335 KnownLive = isLive(cast<SymbolCast>(sym)->getOperand());
336 break;
337 case SymExpr::UnarySymExprKind:
338 KnownLive = isLive(cast<UnarySymExpr>(sym)->getOperand());
339 break;
340 }
341
342 if (KnownLive)
343 markLive(sym);
344
345 return KnownLive;
346}
347
348bool
349SymbolReaper::isLive(const Expr *ExprVal, const LocationContext *ELCtx) const {
350 if (LCtx == nullptr)
351 return false;
352
353 if (LCtx != ELCtx) {
354 // If the reaper's location context is a parent of the expression's
355 // location context, then the expression value is now "out of scope".
356 if (LCtx->isParentOf(ELCtx))
357 return false;
358 return true;
359 }
360
361 // If no statement is provided, everything in this and parent contexts is
362 // live.
363 if (!Loc)
364 return true;
365
366 return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
367}
368
369bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
370 const StackFrameContext *VarContext = VR->getStackFrame();
371
372 if (!VarContext)
373 return true;
374
375 if (!LCtx)
376 return false;
377 const StackFrameContext *CurrentContext = LCtx->getStackFrame();
378
379 if (VarContext == CurrentContext) {
380 // If no statement is provided, everything is live.
381 if (!Loc)
382 return true;
383
384 // Anonymous parameters of an inheriting constructor are live for the entire
385 // duration of the constructor.
386 if (isa<CXXInheritedCtorInitExpr>(Loc))
387 return true;
388
389 if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
390 return true;
391
392 if (!includeStoreBindings)
393 return false;
394
395 unsigned &cachedQuery =
396 const_cast<SymbolReaper *>(this)->includedRegionCache[VR];
397
398 if (cachedQuery) {
399 return cachedQuery == 1;
400 }
401
402 // Query the store to see if the region occurs in any live bindings.
403 if (Store store = reapedStore.getStore()) {
404 bool hasRegion =
405 reapedStore.getStoreManager().includedInBindings(store, VR);
406 cachedQuery = hasRegion ? 1 : 2;
407 return hasRegion;
408 }
409
410 return false;
411 }
412
413 return VarContext->isParentOf(CurrentContext);
414}
Defines the clang::ASTContext interface.
This file defines AnalysisDeclContext, a class that manages the analysis context data for context sen...
static const MemRegion * getRegion(const CallEvent &Call, const MutexDescriptor &Descriptor, bool IsLock)
#define X(type, name)
Definition: Value.h:144
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified.
Defines the Objective-C statement AST node classes.
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:188
CanQualType getSizeType() const
Return the unique type for "size_t" (C99 7.17), defined in <stddef.h>.
StringRef getOpcodeStr() const
Definition: Expr.h:3975
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:520
This represents one expression.
Definition: Expr.h:110
bool isLive(const CFGBlock *B, const VarDecl *D)
Return true if a variable is live at the end of a specified block.
It wraps the AnalysisDeclContext to represent both the call stack with the help of StackFrameContext ...
bool isParentOf(const LocationContext *LC) const
const Decl * getDecl() const
const StackFrameContext * getStackFrame() const
A (possibly-)qualified type.
Definition: Type.h:929
It represents a stack frame of the call stack (based on CallEvent).
int64_t getID(const ASTContext &Context) const
Definition: Stmt.cpp:369
bool isIntegralOrEnumerationType() const
Determine whether this type is an integral or enumeration type.
Definition: Type.h:8625
bool isRecordType() const
Definition: Type.h:8286
bool isUnionType() const
Definition: Type.cpp:704
static StringRef getOpcodeStr(Opcode Op)
getOpcodeStr - Turn an Opcode enum value into the punctuation char it corresponds to,...
Definition: Expr.cpp:1401
static void dumpToStreamImpl(raw_ostream &os, const SymExpr *Value)
static bool isLocType(QualType T)
Definition: SVals.h:262
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:97
LLVM_ATTRIBUTE_RETURNS_NONNULL const MemRegion * getBaseRegion() const
Definition: MemRegion.cpp:1377
SVal - This represents a symbolic expression, which can be either an L-value or an R-value.
Definition: SVals.h:56
llvm::iterator_range< SymExpr::symbol_iterator > symbols() const
Definition: SVals.h:156
Iterator over symbols that the current symbol depends on.
Definition: SymExpr.h:91
bool operator!=(const symbol_iterator &X) const
bool operator==(const symbol_iterator &X) const
Symbolic value.
Definition: SymExpr.h:32
virtual void dumpToStream(raw_ostream &os) const
Definition: SymExpr.h:81
Kind getKind() const
Definition: SymExpr.h:69
virtual void dump() const
SymbolID getSymbolID() const
Get a unique identifier for this symbol.
Definition: SymExpr.h:77
void dumpToStream(raw_ostream &os) const override
StringRef getKindStr() const override
Get a string representation of the kind of the region.
void dumpToStream(raw_ostream &os) const override
QualType getType() const override
LLVM_ATTRIBUTE_RETURNS_NONNULL SymbolRef getParentSymbol() const
StringRef getKindStr() const override
Get a string representation of the kind of the region.
void dumpToStream(raw_ostream &os) const override
QualType getType() const override
LLVM_ATTRIBUTE_RETURNS_NONNULL const TypedValueRegion * getRegion() const
LLVM_ATTRIBUTE_RETURNS_NONNULL const SubRegion * getRegion() const
void dumpToStream(raw_ostream &os) const override
QualType getType() const override
StringRef getKindStr() const override
Get a string representation of the kind of the region.
void addSymbolDependency(const SymbolRef Primary, const SymbolRef Dependent)
Add artificial symbol dependency.
const SymbolRefSmallVectorTy * getDependentSymbols(const SymbolRef Primary)
static bool canSymbolicate(QualType T)
void dumpToStream(raw_ostream &os) const override
LLVM_ATTRIBUTE_RETURNS_NONNULL const MemRegion * getRegion() const
StringRef getKindStr() const override
Get a string representation of the kind of the region.
QualType getType() const override
A class responsible for cleaning up unused symbols.
void markLive(SymbolRef sym)
Unconditionally marks a symbol as live.
void markElementIndicesLive(const MemRegion *region)
void markInUse(SymbolRef sym)
Marks a symbol as important to a checker.
bool isLiveRegion(const MemRegion *region)
void markLazilyCopied(const MemRegion *region)
bool isLive(SymbolRef sym)
void dumpToStream(raw_ostream &os) const override
QualType getType() const override
StringRef getKindStr() const override
Get a string representation of the kind of the region.
void dumpToStream(raw_ostream &os) const override
const VarDecl * getDecl() const override=0
const StackFrameContext * getStackFrame() const
It might return null.
Definition: MemRegion.cpp:165
@ OS
Indicates that the tracking object is a descendant of a referenced-counted OSObject,...
const void * Store
Store - This opaque type encapsulates an immutable mapping from locations to values.
Definition: StoreRef.h:27
The JSON file list parser is used to communicate input to InstallAPI.
BinaryOperatorKind
const FunctionProtoType * T