1 //== SymbolManager.h - Management of Symbolic Values ------------*- C++ -*--==//
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/Analysis/Analyses/LiveVariables.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
19 #include "llvm/Support/raw_ostream.h"
20
21 using namespace clang;
22 using namespace ento;
23
anchor()24 void SymExpr::anchor() { }
25
dump() const26 void SymExpr::dump() const {
27 dumpToStream(llvm::errs());
28 }
29
dumpToStream(raw_ostream & os) const30 void SymIntExpr::dumpToStream(raw_ostream &os) const {
31 os << '(';
32 getLHS()->dumpToStream(os);
33 os << ") "
34 << BinaryOperator::getOpcodeStr(getOpcode()) << ' '
35 << getRHS().getZExtValue();
36 if (getRHS().isUnsigned())
37 os << 'U';
38 }
39
dumpToStream(raw_ostream & os) const40 void IntSymExpr::dumpToStream(raw_ostream &os) const {
41 os << getLHS().getZExtValue();
42 if (getLHS().isUnsigned())
43 os << 'U';
44 os << ' '
45 << BinaryOperator::getOpcodeStr(getOpcode())
46 << " (";
47 getRHS()->dumpToStream(os);
48 os << ')';
49 }
50
dumpToStream(raw_ostream & os) const51 void SymSymExpr::dumpToStream(raw_ostream &os) const {
52 os << '(';
53 getLHS()->dumpToStream(os);
54 os << ") "
55 << BinaryOperator::getOpcodeStr(getOpcode())
56 << " (";
57 getRHS()->dumpToStream(os);
58 os << ')';
59 }
60
dumpToStream(raw_ostream & os) const61 void SymbolCast::dumpToStream(raw_ostream &os) const {
62 os << '(' << ToTy.getAsString() << ") (";
63 Operand->dumpToStream(os);
64 os << ')';
65 }
66
dumpToStream(raw_ostream & os) const67 void SymbolConjured::dumpToStream(raw_ostream &os) const {
68 os << "conj_$" << getSymbolID() << '{' << T.getAsString() << '}';
69 }
70
dumpToStream(raw_ostream & os) const71 void SymbolDerived::dumpToStream(raw_ostream &os) const {
72 os << "derived_$" << getSymbolID() << '{'
73 << getParentSymbol() << ',' << getRegion() << '}';
74 }
75
dumpToStream(raw_ostream & os) const76 void SymbolExtent::dumpToStream(raw_ostream &os) const {
77 os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
78 }
79
dumpToStream(raw_ostream & os) const80 void SymbolMetadata::dumpToStream(raw_ostream &os) const {
81 os << "meta_$" << getSymbolID() << '{'
82 << getRegion() << ',' << T.getAsString() << '}';
83 }
84
anchor()85 void SymbolData::anchor() { }
86
dumpToStream(raw_ostream & os) const87 void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
88 os << "reg_$" << getSymbolID() << "<" << R << ">";
89 }
90
operator ==(const symbol_iterator & X) const91 bool SymExpr::symbol_iterator::operator==(const symbol_iterator &X) const {
92 return itr == X.itr;
93 }
94
operator !=(const symbol_iterator & X) const95 bool SymExpr::symbol_iterator::operator!=(const symbol_iterator &X) const {
96 return itr != X.itr;
97 }
98
symbol_iterator(const SymExpr * SE)99 SymExpr::symbol_iterator::symbol_iterator(const SymExpr *SE) {
100 itr.push_back(SE);
101 }
102
operator ++()103 SymExpr::symbol_iterator &SymExpr::symbol_iterator::operator++() {
104 assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
105 expand();
106 return *this;
107 }
108
operator *()109 SymbolRef SymExpr::symbol_iterator::operator*() {
110 assert(!itr.empty() && "attempting to dereference an 'end' iterator");
111 return itr.back();
112 }
113
expand()114 void SymExpr::symbol_iterator::expand() {
115 const SymExpr *SE = itr.back();
116 itr.pop_back();
117
118 switch (SE->getKind()) {
119 case SymExpr::RegionValueKind:
120 case SymExpr::ConjuredKind:
121 case SymExpr::DerivedKind:
122 case SymExpr::ExtentKind:
123 case SymExpr::MetadataKind:
124 return;
125 case SymExpr::CastSymbolKind:
126 itr.push_back(cast<SymbolCast>(SE)->getOperand());
127 return;
128 case SymExpr::SymIntKind:
129 itr.push_back(cast<SymIntExpr>(SE)->getLHS());
130 return;
131 case SymExpr::IntSymKind:
132 itr.push_back(cast<IntSymExpr>(SE)->getRHS());
133 return;
134 case SymExpr::SymSymKind: {
135 const SymSymExpr *x = cast<SymSymExpr>(SE);
136 itr.push_back(x->getLHS());
137 itr.push_back(x->getRHS());
138 return;
139 }
140 }
141 llvm_unreachable("unhandled expansion case");
142 }
143
computeComplexity() const144 unsigned SymExpr::computeComplexity() const {
145 unsigned R = 0;
146 for (symbol_iterator I = symbol_begin(), E = symbol_end(); I != E; ++I)
147 R++;
148 return R;
149 }
150
151 const SymbolRegionValue*
getRegionValueSymbol(const TypedValueRegion * R)152 SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
153 llvm::FoldingSetNodeID profile;
154 SymbolRegionValue::Profile(profile, R);
155 void *InsertPos;
156 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
157 if (!SD) {
158 SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
159 new (SD) SymbolRegionValue(SymbolCounter, R);
160 DataSet.InsertNode(SD, InsertPos);
161 ++SymbolCounter;
162 }
163
164 return cast<SymbolRegionValue>(SD);
165 }
166
conjureSymbol(const Stmt * E,const LocationContext * LCtx,QualType T,unsigned Count,const void * SymbolTag)167 const SymbolConjured* SymbolManager::conjureSymbol(const Stmt *E,
168 const LocationContext *LCtx,
169 QualType T,
170 unsigned Count,
171 const void *SymbolTag) {
172 llvm::FoldingSetNodeID profile;
173 SymbolConjured::Profile(profile, E, T, Count, LCtx, SymbolTag);
174 void *InsertPos;
175 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
176 if (!SD) {
177 SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
178 new (SD) SymbolConjured(SymbolCounter, E, LCtx, T, Count, SymbolTag);
179 DataSet.InsertNode(SD, InsertPos);
180 ++SymbolCounter;
181 }
182
183 return cast<SymbolConjured>(SD);
184 }
185
186 const SymbolDerived*
getDerivedSymbol(SymbolRef parentSymbol,const TypedValueRegion * R)187 SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
188 const TypedValueRegion *R) {
189
190 llvm::FoldingSetNodeID profile;
191 SymbolDerived::Profile(profile, parentSymbol, R);
192 void *InsertPos;
193 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
194 if (!SD) {
195 SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
196 new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
197 DataSet.InsertNode(SD, InsertPos);
198 ++SymbolCounter;
199 }
200
201 return cast<SymbolDerived>(SD);
202 }
203
204 const SymbolExtent*
getExtentSymbol(const SubRegion * R)205 SymbolManager::getExtentSymbol(const SubRegion *R) {
206 llvm::FoldingSetNodeID profile;
207 SymbolExtent::Profile(profile, R);
208 void *InsertPos;
209 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
210 if (!SD) {
211 SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
212 new (SD) SymbolExtent(SymbolCounter, R);
213 DataSet.InsertNode(SD, InsertPos);
214 ++SymbolCounter;
215 }
216
217 return cast<SymbolExtent>(SD);
218 }
219
220 const SymbolMetadata*
getMetadataSymbol(const MemRegion * R,const Stmt * S,QualType T,unsigned Count,const void * SymbolTag)221 SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
222 unsigned Count, const void *SymbolTag) {
223
224 llvm::FoldingSetNodeID profile;
225 SymbolMetadata::Profile(profile, R, S, T, Count, SymbolTag);
226 void *InsertPos;
227 SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
228 if (!SD) {
229 SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
230 new (SD) SymbolMetadata(SymbolCounter, R, S, T, Count, SymbolTag);
231 DataSet.InsertNode(SD, InsertPos);
232 ++SymbolCounter;
233 }
234
235 return cast<SymbolMetadata>(SD);
236 }
237
238 const SymbolCast*
getCastSymbol(const SymExpr * Op,QualType From,QualType To)239 SymbolManager::getCastSymbol(const SymExpr *Op,
240 QualType From, QualType To) {
241 llvm::FoldingSetNodeID ID;
242 SymbolCast::Profile(ID, Op, From, To);
243 void *InsertPos;
244 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
245 if (!data) {
246 data = (SymbolCast*) BPAlloc.Allocate<SymbolCast>();
247 new (data) SymbolCast(Op, From, To);
248 DataSet.InsertNode(data, InsertPos);
249 }
250
251 return cast<SymbolCast>(data);
252 }
253
getSymIntExpr(const SymExpr * lhs,BinaryOperator::Opcode op,const llvm::APSInt & v,QualType t)254 const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
255 BinaryOperator::Opcode op,
256 const llvm::APSInt& v,
257 QualType t) {
258 llvm::FoldingSetNodeID ID;
259 SymIntExpr::Profile(ID, lhs, op, v, t);
260 void *InsertPos;
261 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
262
263 if (!data) {
264 data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
265 new (data) SymIntExpr(lhs, op, v, t);
266 DataSet.InsertNode(data, InsertPos);
267 }
268
269 return cast<SymIntExpr>(data);
270 }
271
getIntSymExpr(const llvm::APSInt & lhs,BinaryOperator::Opcode op,const SymExpr * rhs,QualType t)272 const IntSymExpr *SymbolManager::getIntSymExpr(const llvm::APSInt& lhs,
273 BinaryOperator::Opcode op,
274 const SymExpr *rhs,
275 QualType t) {
276 llvm::FoldingSetNodeID ID;
277 IntSymExpr::Profile(ID, lhs, op, rhs, t);
278 void *InsertPos;
279 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
280
281 if (!data) {
282 data = (IntSymExpr*) BPAlloc.Allocate<IntSymExpr>();
283 new (data) IntSymExpr(lhs, op, rhs, t);
284 DataSet.InsertNode(data, InsertPos);
285 }
286
287 return cast<IntSymExpr>(data);
288 }
289
getSymSymExpr(const SymExpr * lhs,BinaryOperator::Opcode op,const SymExpr * rhs,QualType t)290 const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
291 BinaryOperator::Opcode op,
292 const SymExpr *rhs,
293 QualType t) {
294 llvm::FoldingSetNodeID ID;
295 SymSymExpr::Profile(ID, lhs, op, rhs, t);
296 void *InsertPos;
297 SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
298
299 if (!data) {
300 data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
301 new (data) SymSymExpr(lhs, op, rhs, t);
302 DataSet.InsertNode(data, InsertPos);
303 }
304
305 return cast<SymSymExpr>(data);
306 }
307
getType() const308 QualType SymbolConjured::getType() const {
309 return T;
310 }
311
getType() const312 QualType SymbolDerived::getType() const {
313 return R->getValueType();
314 }
315
getType() const316 QualType SymbolExtent::getType() const {
317 ASTContext &Ctx = R->getMemRegionManager()->getContext();
318 return Ctx.getSizeType();
319 }
320
getType() const321 QualType SymbolMetadata::getType() const {
322 return T;
323 }
324
getType() const325 QualType SymbolRegionValue::getType() const {
326 return R->getValueType();
327 }
328
~SymbolManager()329 SymbolManager::~SymbolManager() {
330 for (SymbolDependTy::const_iterator I = SymbolDependencies.begin(),
331 E = SymbolDependencies.end(); I != E; ++I) {
332 delete I->second;
333 }
334
335 }
336
canSymbolicate(QualType T)337 bool SymbolManager::canSymbolicate(QualType T) {
338 T = T.getCanonicalType();
339
340 if (Loc::isLocType(T))
341 return true;
342
343 if (T->isIntegralOrEnumerationType())
344 return true;
345
346 if (T->isRecordType() && !T->isUnionType())
347 return true;
348
349 return false;
350 }
351
addSymbolDependency(const SymbolRef Primary,const SymbolRef Dependent)352 void SymbolManager::addSymbolDependency(const SymbolRef Primary,
353 const SymbolRef Dependent) {
354 SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
355 SymbolRefSmallVectorTy *dependencies = 0;
356 if (I == SymbolDependencies.end()) {
357 dependencies = new SymbolRefSmallVectorTy();
358 SymbolDependencies[Primary] = dependencies;
359 } else {
360 dependencies = I->second;
361 }
362 dependencies->push_back(Dependent);
363 }
364
getDependentSymbols(const SymbolRef Primary)365 const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
366 const SymbolRef Primary) {
367 SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
368 if (I == SymbolDependencies.end())
369 return 0;
370 return I->second;
371 }
372
markDependentsLive(SymbolRef sym)373 void SymbolReaper::markDependentsLive(SymbolRef sym) {
374 // Do not mark dependents more then once.
375 SymbolMapTy::iterator LI = TheLiving.find(sym);
376 assert(LI != TheLiving.end() && "The primary symbol is not live.");
377 if (LI->second == HaveMarkedDependents)
378 return;
379 LI->second = HaveMarkedDependents;
380
381 if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
382 for (SymbolRefSmallVectorTy::const_iterator I = Deps->begin(),
383 E = Deps->end(); I != E; ++I) {
384 if (TheLiving.find(*I) != TheLiving.end())
385 continue;
386 markLive(*I);
387 }
388 }
389 }
390
markLive(SymbolRef sym)391 void SymbolReaper::markLive(SymbolRef sym) {
392 TheLiving[sym] = NotProcessed;
393 TheDead.erase(sym);
394 markDependentsLive(sym);
395 }
396
markLive(const MemRegion * region)397 void SymbolReaper::markLive(const MemRegion *region) {
398 RegionRoots.insert(region);
399 }
400
markInUse(SymbolRef sym)401 void SymbolReaper::markInUse(SymbolRef sym) {
402 if (isa<SymbolMetadata>(sym))
403 MetadataInUse.insert(sym);
404 }
405
maybeDead(SymbolRef sym)406 bool SymbolReaper::maybeDead(SymbolRef sym) {
407 if (isLive(sym))
408 return false;
409
410 TheDead.insert(sym);
411 return true;
412 }
413
isLiveRegion(const MemRegion * MR)414 bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
415 if (RegionRoots.count(MR))
416 return true;
417
418 MR = MR->getBaseRegion();
419
420 if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR))
421 return isLive(SR->getSymbol());
422
423 if (const VarRegion *VR = dyn_cast<VarRegion>(MR))
424 return isLive(VR, true);
425
426 // FIXME: This is a gross over-approximation. What we really need is a way to
427 // tell if anything still refers to this region. Unlike SymbolicRegions,
428 // AllocaRegions don't have associated symbols, though, so we don't actually
429 // have a way to track their liveness.
430 if (isa<AllocaRegion>(MR))
431 return true;
432
433 if (isa<CXXThisRegion>(MR))
434 return true;
435
436 if (isa<MemSpaceRegion>(MR))
437 return true;
438
439 return false;
440 }
441
isLive(SymbolRef sym)442 bool SymbolReaper::isLive(SymbolRef sym) {
443 if (TheLiving.count(sym)) {
444 markDependentsLive(sym);
445 return true;
446 }
447
448 bool KnownLive;
449
450 switch (sym->getKind()) {
451 case SymExpr::RegionValueKind:
452 KnownLive = isLiveRegion(cast<SymbolRegionValue>(sym)->getRegion());
453 break;
454 case SymExpr::ConjuredKind:
455 KnownLive = false;
456 break;
457 case SymExpr::DerivedKind:
458 KnownLive = isLive(cast<SymbolDerived>(sym)->getParentSymbol());
459 break;
460 case SymExpr::ExtentKind:
461 KnownLive = isLiveRegion(cast<SymbolExtent>(sym)->getRegion());
462 break;
463 case SymExpr::MetadataKind:
464 KnownLive = MetadataInUse.count(sym) &&
465 isLiveRegion(cast<SymbolMetadata>(sym)->getRegion());
466 if (KnownLive)
467 MetadataInUse.erase(sym);
468 break;
469 case SymExpr::SymIntKind:
470 KnownLive = isLive(cast<SymIntExpr>(sym)->getLHS());
471 break;
472 case SymExpr::IntSymKind:
473 KnownLive = isLive(cast<IntSymExpr>(sym)->getRHS());
474 break;
475 case SymExpr::SymSymKind:
476 KnownLive = isLive(cast<SymSymExpr>(sym)->getLHS()) &&
477 isLive(cast<SymSymExpr>(sym)->getRHS());
478 break;
479 case SymExpr::CastSymbolKind:
480 KnownLive = isLive(cast<SymbolCast>(sym)->getOperand());
481 break;
482 }
483
484 if (KnownLive)
485 markLive(sym);
486
487 return KnownLive;
488 }
489
490 bool
isLive(const Stmt * ExprVal,const LocationContext * ELCtx) const491 SymbolReaper::isLive(const Stmt *ExprVal, const LocationContext *ELCtx) const {
492 if (LCtx == 0)
493 return false;
494
495 if (LCtx != ELCtx) {
496 // If the reaper's location context is a parent of the expression's
497 // location context, then the expression value is now "out of scope".
498 if (LCtx->isParentOf(ELCtx))
499 return false;
500 return true;
501 }
502
503 // If no statement is provided, everything is this and parent contexts is live.
504 if (!Loc)
505 return true;
506
507 return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
508 }
509
isLive(const VarRegion * VR,bool includeStoreBindings) const510 bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
511 const StackFrameContext *VarContext = VR->getStackFrame();
512
513 if (!VarContext)
514 return true;
515
516 if (!LCtx)
517 return false;
518 const StackFrameContext *CurrentContext = LCtx->getCurrentStackFrame();
519
520 if (VarContext == CurrentContext) {
521 // If no statement is provided, everything is live.
522 if (!Loc)
523 return true;
524
525 if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
526 return true;
527
528 if (!includeStoreBindings)
529 return false;
530
531 unsigned &cachedQuery =
532 const_cast<SymbolReaper*>(this)->includedRegionCache[VR];
533
534 if (cachedQuery) {
535 return cachedQuery == 1;
536 }
537
538 // Query the store to see if the region occurs in any live bindings.
539 if (Store store = reapedStore.getStore()) {
540 bool hasRegion =
541 reapedStore.getStoreManager().includedInBindings(store, VR);
542 cachedQuery = hasRegion ? 1 : 2;
543 return hasRegion;
544 }
545
546 return false;
547 }
548
549 return VarContext->isParentOf(CurrentContext);
550 }
551
~SymbolVisitor()552 SymbolVisitor::~SymbolVisitor() {}
553