clang 8.0.0

SymbolManager.cpp
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1 //===- SymbolManager.h - Management of Symbolic Values --------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines SymbolManager, a class that manages symbolic values
11 // created for use by ExprEngine and related classes.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/Analysis/Analyses/LiveVariables.h"
19 #include "clang/Analysis/AnalysisDeclContext.h"
20 #include "clang/Basic/LLVM.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.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
33 using namespace clang;
34 using namespace ento;
35
36 void SymExpr::anchor() {}
37
38 LLVM_DUMP_METHOD void SymExpr::dump() const {
39 dumpToStream(llvm::errs());
40 }
41
42 void SymIntExpr::dumpToStream(raw_ostream &os) const {
43 os << '(';
44 getLHS()->dumpToStream(os);
45 os << ") "
46 << BinaryOperator::getOpcodeStr(getOpcode()) << ' ';
47 if (getRHS().isUnsigned())
48 os << getRHS().getZExtValue();
49 else
50 os << getRHS().getSExtValue();
51 if (getRHS().isUnsigned())
52 os << 'U';
53 }
54
55 void IntSymExpr::dumpToStream(raw_ostream &os) const {
56 if (getLHS().isUnsigned())
57 os << getLHS().getZExtValue();
58 else
59 os << getLHS().getSExtValue();
60 if (getLHS().isUnsigned())
61 os << 'U';
62 os << ' '
63 << BinaryOperator::getOpcodeStr(getOpcode())
64 << " (";
65 getRHS()->dumpToStream(os);
66 os << ')';
67 }
68
69 void SymSymExpr::dumpToStream(raw_ostream &os) const {
70 os << '(';
71 getLHS()->dumpToStream(os);
72 os << ") "
73 << BinaryOperator::getOpcodeStr(getOpcode())
74 << " (";
75 getRHS()->dumpToStream(os);
76 os << ')';
77 }
78
79 void SymbolCast::dumpToStream(raw_ostream &os) const {
80 os << '(' << ToTy.getAsString() << ") (";
81 Operand->dumpToStream(os);
82 os << ')';
83 }
84
85 void SymbolConjured::dumpToStream(raw_ostream &os) const {
86 os << "conj_$" << getSymbolID() << '{' << T.getAsString() << ", LC"
87 << LCtx->getID();
88 if (S)
89 os << ", S" << S->getID(LCtx->getDecl()->getASTContext());
90 else
91 os << ", no stmt";
92 os << ", #" << Count << '}';
93 }
94
95 void SymbolDerived::dumpToStream(raw_ostream &os) const {
96 os << "derived_$" << getSymbolID() << '{'
97 << getParentSymbol() << ',' << getRegion() << '}';
98 }
99
100 void SymbolExtent::dumpToStream(raw_ostream &os) const {
101 os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
102 }
103
104 void SymbolMetadata::dumpToStream(raw_ostream &os) const {
105 os << "meta_$" << getSymbolID() << '{'
106 << getRegion() << ',' << T.getAsString() << '}';
107 }
108
109 void SymbolData::anchor() {}
110
111 void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
112 os << "reg_$" << getSymbolID()
113 << '<' << getType().getAsString() << ' ' << R << '>';
114 }
115
116 bool SymExpr::symbol_iterator::operator==(const symbol_iterator &X) const {
117 return itr == X.itr;
118 }
119
120 bool SymExpr::symbol_iterator::operator!=(const symbol_iterator &X) const {
121 return itr != X.itr;
122 }
123
124 SymExpr::symbol_iterator::symbol_iterator(const SymExpr *SE) {
125 itr.push_back(SE);
126 }
127
128 SymExpr::symbol_iterator &SymExpr::symbol_iterator::operator++() {
129 assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
130 expand();
131 return *this;
132 }
133
134 SymbolRef SymExpr::symbol_iterator::operator*() {
135 assert(!itr.empty() && "attempting to dereference an 'end' iterator");
136 return itr.back();
137 }
138
139 void SymExpr::symbol_iterator::expand() {
140 const SymExpr *SE = itr.pop_back_val();
141
142 switch (SE->getKind()) {
143 case SymExpr::SymbolRegionValueKind:
144 case SymExpr::SymbolConjuredKind:
145 case SymExpr::SymbolDerivedKind:
146 case SymExpr::SymbolExtentKind:
147 case SymExpr::SymbolMetadataKind:
148 return;
149 case SymExpr::SymbolCastKind:
150 itr.push_back(cast<SymbolCast>(SE)->getOperand());
151 return;
152 case SymExpr::SymIntExprKind:
153 itr.push_back(cast<SymIntExpr>(SE)->getLHS());
154 return;
155 case SymExpr::IntSymExprKind:
156 itr.push_back(cast<IntSymExpr>(SE)->getRHS());
157 return;
158 case SymExpr::SymSymExprKind: {
159 const auto *x = cast<SymSymExpr>(SE);
160 itr.push_back(x->getLHS());
161 itr.push_back(x->getRHS());
162 return;
163 }
164 }
165 llvm_unreachable("unhandled expansion case");
166 }
167
168 const SymbolRegionValue*
169 SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
170 llvm::FoldingSetNodeID profile;
171 SymbolRegionValue::Profile(profile, R);
172 void *InsertPos;
173 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
174 if (!SD) {
175 SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
176 new (SD) SymbolRegionValue(SymbolCounter, R);
177 DataSet.InsertNode(SD, InsertPos);
178 ++SymbolCounter;
179 }
180
181 return cast<SymbolRegionValue>(SD);
182 }
183
184 const SymbolConjured* SymbolManager::conjureSymbol(const Stmt *E,
185 const LocationContext *LCtx,
186 QualType T,
187 unsigned Count,
188 const void *SymbolTag) {
189 llvm::FoldingSetNodeID profile;
190 SymbolConjured::Profile(profile, E, T, Count, LCtx, SymbolTag);
191 void *InsertPos;
192 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
193 if (!SD) {
194 SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
195 new (SD) SymbolConjured(SymbolCounter, E, LCtx, T, Count, SymbolTag);
196 DataSet.InsertNode(SD, InsertPos);
197 ++SymbolCounter;
198 }
199
200 return cast<SymbolConjured>(SD);
201 }
202
203 const SymbolDerived*
204 SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
205 const TypedValueRegion *R) {
206 llvm::FoldingSetNodeID profile;
207 SymbolDerived::Profile(profile, parentSymbol, R);
208 void *InsertPos;
209 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
210 if (!SD) {
211 SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
212 new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
213 DataSet.InsertNode(SD, InsertPos);
214 ++SymbolCounter;
215 }
216
217 return cast<SymbolDerived>(SD);
218 }
219
220 const SymbolExtent*
221 SymbolManager::getExtentSymbol(const SubRegion *R) {
222 llvm::FoldingSetNodeID profile;
223 SymbolExtent::Profile(profile, R);
224 void *InsertPos;
225 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
226 if (!SD) {
227 SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
228 new (SD) SymbolExtent(SymbolCounter, R);
229 DataSet.InsertNode(SD, InsertPos);
230 ++SymbolCounter;
231 }
232
233 return cast<SymbolExtent>(SD);
234 }
235
236 const SymbolMetadata *
237 SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
238 const LocationContext *LCtx,
239 unsigned Count, const void *SymbolTag) {
240 llvm::FoldingSetNodeID profile;
241 SymbolMetadata::Profile(profile, R, S, T, LCtx, Count, SymbolTag);
242 void *InsertPos;
243 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
244 if (!SD) {
245 SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
246 new (SD) SymbolMetadata(SymbolCounter, R, S, T, LCtx, Count, SymbolTag);
247 DataSet.InsertNode(SD, InsertPos);
248 ++SymbolCounter;
249 }
250
251 return cast<SymbolMetadata>(SD);
252 }
253
254 const SymbolCast*
255 SymbolManager::getCastSymbol(const SymExpr *Op,
256 QualType From, QualType To) {
257 llvm::FoldingSetNodeID ID;
258 SymbolCast::Profile(ID, Op, From, To);
259 void *InsertPos;
260 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
261 if (!data) {
262 data = (SymbolCast*) BPAlloc.Allocate<SymbolCast>();
263 new (data) SymbolCast(Op, From, To);
264 DataSet.InsertNode(data, InsertPos);
265 }
266
267 return cast<SymbolCast>(data);
268 }
269
270 const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
271 BinaryOperator::Opcode op,
272 const llvm::APSInt& v,
273 QualType t) {
274 llvm::FoldingSetNodeID ID;
275 SymIntExpr::Profile(ID, lhs, op, v, t);
276 void *InsertPos;
277 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
278
279 if (!data) {
280 data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
281 new (data) SymIntExpr(lhs, op, v, t);
282 DataSet.InsertNode(data, InsertPos);
283 }
284
285 return cast<SymIntExpr>(data);
286 }
287
288 const IntSymExpr *SymbolManager::getIntSymExpr(const llvm::APSInt& lhs,
289 BinaryOperator::Opcode op,
290 const SymExpr *rhs,
291 QualType t) {
292 llvm::FoldingSetNodeID ID;
293 IntSymExpr::Profile(ID, lhs, op, rhs, t);
294 void *InsertPos;
295 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
296
297 if (!data) {
298 data = (IntSymExpr*) BPAlloc.Allocate<IntSymExpr>();
299 new (data) IntSymExpr(lhs, op, rhs, t);
300 DataSet.InsertNode(data, InsertPos);
301 }
302
303 return cast<IntSymExpr>(data);
304 }
305
306 const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
307 BinaryOperator::Opcode op,
308 const SymExpr *rhs,
309 QualType t) {
310 llvm::FoldingSetNodeID ID;
311 SymSymExpr::Profile(ID, lhs, op, rhs, t);
312 void *InsertPos;
313 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
314
315 if (!data) {
316 data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
317 new (data) SymSymExpr(lhs, op, rhs, t);
318 DataSet.InsertNode(data, InsertPos);
319 }
320
321 return cast<SymSymExpr>(data);
322 }
323
324 QualType SymbolConjured::getType() const {
325 return T;
326 }
327
328 QualType SymbolDerived::getType() const {
329 return R->getValueType();
330 }
331
332 QualType SymbolExtent::getType() const {
333 ASTContext &Ctx = R->getMemRegionManager()->getContext();
334 return Ctx.getSizeType();
335 }
336
337 QualType SymbolMetadata::getType() const {
338 return T;
339 }
340
341 QualType SymbolRegionValue::getType() const {
342 return R->getValueType();
343 }
344
345 SymbolManager::~SymbolManager() {
346 llvm::DeleteContainerSeconds(SymbolDependencies);
347 }
348
349 bool SymbolManager::canSymbolicate(QualType T) {
350 T = T.getCanonicalType();
351
352 if (Loc::isLocType(T))
353 return true;
354
355 if (T->isIntegralOrEnumerationType())
356 return true;
357
358 if (T->isRecordType() && !T->isUnionType())
359 return true;
360
361 return false;
362 }
363
364 void SymbolManager::addSymbolDependency(const SymbolRef Primary,
365 const SymbolRef Dependent) {
366 SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
367 SymbolRefSmallVectorTy *dependencies = nullptr;
368 if (I == SymbolDependencies.end()) {
369 dependencies = new SymbolRefSmallVectorTy();
370 SymbolDependencies[Primary] = dependencies;
371 } else {
372 dependencies = I->second;
373 }
374 dependencies->push_back(Dependent);
375 }
376
377 const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
378 const SymbolRef Primary) {
379 SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
380 if (I == SymbolDependencies.end())
381 return nullptr;
382 return I->second;
383 }
384
385 void SymbolReaper::markDependentsLive(SymbolRef sym) {
386 // Do not mark dependents more then once.
387 SymbolMapTy::iterator LI = TheLiving.find(sym);
388 assert(LI != TheLiving.end() && "The primary symbol is not live.");
389 if (LI->second == HaveMarkedDependents)
390 return;
391 LI->second = HaveMarkedDependents;
392
393 if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
394 for (const auto I : *Deps) {
395 if (TheLiving.find(I) != TheLiving.end())
396 continue;
397 markLive(I);
398 }
399 }
400 }
401
402 void SymbolReaper::markLive(SymbolRef sym) {
403 TheLiving[sym] = NotProcessed;
404 markDependentsLive(sym);
405 }
406
407 void SymbolReaper::markLive(const MemRegion *region) {
408 RegionRoots.insert(region);
409 markElementIndicesLive(region);
410 }
411
412 void SymbolReaper::markElementIndicesLive(const MemRegion *region) {
413 for (auto SR = dyn_cast<SubRegion>(region); SR;
414 SR = dyn_cast<SubRegion>(SR->getSuperRegion())) {
415 if (const auto ER = dyn_cast<ElementRegion>(SR)) {
416 SVal Idx = ER->getIndex();
417 for (auto SI = Idx.symbol_begin(), SE = Idx.symbol_end(); SI != SE; ++SI)
418 markLive(*SI);
419 }
420 }
421 }
422
423 void SymbolReaper::markInUse(SymbolRef sym) {
424 if (isa<SymbolMetadata>(sym))
425 MetadataInUse.insert(sym);
426 }
427
428 bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
429 if (RegionRoots.count(MR))
430 return true;
431
432 MR = MR->getBaseRegion();
433
434 if (const auto *SR = dyn_cast<SymbolicRegion>(MR))
435 return isLive(SR->getSymbol());
436
437 if (const auto *VR = dyn_cast<VarRegion>(MR))
438 return isLive(VR, true);
439
440 // FIXME: This is a gross over-approximation. What we really need is a way to
441 // tell if anything still refers to this region. Unlike SymbolicRegions,
442 // AllocaRegions don't have associated symbols, though, so we don't actually
443 // have a way to track their liveness.
444 if (isa<AllocaRegion>(MR))
445 return true;
446
447 if (isa<CXXThisRegion>(MR))
448 return true;
449
450 if (isa<MemSpaceRegion>(MR))
451 return true;
452
453 if (isa<CodeTextRegion>(MR))
454 return true;
455
456 return false;
457 }
458
459 bool SymbolReaper::isLive(SymbolRef sym) {
460 if (TheLiving.count(sym)) {
461 markDependentsLive(sym);
462 return true;
463 }
464
465 bool KnownLive;
466
467 switch (sym->getKind()) {
468 case SymExpr::SymbolRegionValueKind:
469 KnownLive = isLiveRegion(cast<SymbolRegionValue>(sym)->getRegion());
470 break;
471 case SymExpr::SymbolConjuredKind:
472 KnownLive = false;
473 break;
474 case SymExpr::SymbolDerivedKind:
475 KnownLive = isLive(cast<SymbolDerived>(sym)->getParentSymbol());
476 break;
477 case SymExpr::SymbolExtentKind:
478 KnownLive = isLiveRegion(cast<SymbolExtent>(sym)->getRegion());
479 break;
480 case SymExpr::SymbolMetadataKind:
481 KnownLive = MetadataInUse.count(sym) &&
482 isLiveRegion(cast<SymbolMetadata>(sym)->getRegion());
483 if (KnownLive)
484 MetadataInUse.erase(sym);
485 break;
486 case SymExpr::SymIntExprKind:
487 KnownLive = isLive(cast<SymIntExpr>(sym)->getLHS());
488 break;
489 case SymExpr::IntSymExprKind:
490 KnownLive = isLive(cast<IntSymExpr>(sym)->getRHS());
491 break;
492 case SymExpr::SymSymExprKind:
493 KnownLive = isLive(cast<SymSymExpr>(sym)->getLHS()) &&
494 isLive(cast<SymSymExpr>(sym)->getRHS());
495 break;
496 case SymExpr::SymbolCastKind:
497 KnownLive = isLive(cast<SymbolCast>(sym)->getOperand());
498 break;
499 }
500
501 if (KnownLive)
502 markLive(sym);
503
504 return KnownLive;
505 }
506
507 bool
508 SymbolReaper::isLive(const Stmt *ExprVal, const LocationContext *ELCtx) const {
509 if (LCtx == nullptr)
510 return false;
511
512 if (LCtx != ELCtx) {
513 // If the reaper's location context is a parent of the expression's
514 // location context, then the expression value is now "out of scope".
515 if (LCtx->isParentOf(ELCtx))
516 return false;
517 return true;
518 }
519
520 // If no statement is provided, everything is this and parent contexts is live.
521 if (!Loc)
522 return true;
523
524 return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
525 }
526
527 bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
528 const StackFrameContext *VarContext = VR->getStackFrame();
529
530 if (!VarContext)
531 return true;
532
533 if (!LCtx)
534 return false;
535 const StackFrameContext *CurrentContext = LCtx->getStackFrame();
536
537 if (VarContext == CurrentContext) {
538 // If no statement is provided, everything is live.
539 if (!Loc)
540 return true;
541
542 if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
543 return true;
544
545 if (!includeStoreBindings)
546 return false;
547
548 unsigned &cachedQuery =
549 const_cast<SymbolReaper *>(this)->includedRegionCache[VR];
550
551 if (cachedQuery) {
552 return cachedQuery == 1;
553 }
554
555 // Query the store to see if the region occurs in any live bindings.
556 if (Store store = reapedStore.getStore()) {
557 bool hasRegion =
558 reapedStore.getStoreManager().includedInBindings(store, VR);
559 cachedQuery = hasRegion ? 1 : 2;
560 return hasRegion;
561 }
562
563 return false;
564 }
565
566 return VarContext->isParentOf(CurrentContext);
567 }
ASTContext.h
Defines the clang::ASTContext interface.
ento
SVals.h
MemRegion.h
clang::ento::SymbolDerived::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:95
clang::ento::SymExpr::dump
virtual void dump() const
Definition: SymbolManager.cpp:38
clang::ento::SymbolCast::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:79
Store.h
clang::BinaryOperator::getOpcodeStr
StringRef getOpcodeStr() const
Definition: Expr.h:3343
clang::ento::SymExpr::dumpToStream
virtual void dumpToStream(raw_ostream &os) const
Definition: SymExpr.h:61
LLVM.h
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
clang::ento::SymExpr::getType
virtual QualType getType() const =0
AnalysisDeclContext.h
clang::ento::SymbolRegionValue::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:111
LiveVariables.h
SymbolManager.h
clang::ento::SymbolExtent::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:100
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:22
IteratorComparison::getOpcode
BinaryOperator::Opcode getOpcode(const SymExpr *SE)
clang::QualType::getAsString
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:971
clang::ento::SymbolMetadata::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:104
SymExpr.h
clang::ento::SymIntExpr::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:42
Expr.h
clang::ento::SymbolConjured::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:85
clang::ento::SymSymExpr::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:69
clang::ento::IntSymExpr::dumpToStream
void dumpToStream(raw_ostream &os) const override
Definition: SymbolManager.cpp:55