clang  8.0.0svn
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 
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Expr.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 
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 << ") "
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 << ' '
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 << ") "
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_$" << getSymbolID() << '{' << T.getAsString()
87  << ", LC" << LCtx->getID() << ", S" << S->getID(
88  LCtx->getDecl()->getASTContext()) << ", #" << Count
89  << '}';
90 }
91 
92 void SymbolDerived::dumpToStream(raw_ostream &os) const {
93  os << "derived_$" << getSymbolID() << '{'
94  << getParentSymbol() << ',' << getRegion() << '}';
95 }
96 
97 void SymbolExtent::dumpToStream(raw_ostream &os) const {
98  os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
99 }
100 
101 void SymbolMetadata::dumpToStream(raw_ostream &os) const {
102  os << "meta_$" << getSymbolID() << '{'
103  << getRegion() << ',' << T.getAsString() << '}';
104 }
105 
106 void SymbolData::anchor() {}
107 
108 void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
109  os << "reg_$" << getSymbolID()
110  << '<' << getType().getAsString() << ' ' << R << '>';
111 }
112 
113 bool SymExpr::symbol_iterator::operator==(const symbol_iterator &X) const {
114  return itr == X.itr;
115 }
116 
117 bool SymExpr::symbol_iterator::operator!=(const symbol_iterator &X) const {
118  return itr != X.itr;
119 }
120 
121 SymExpr::symbol_iterator::symbol_iterator(const SymExpr *SE) {
122  itr.push_back(SE);
123 }
124 
125 SymExpr::symbol_iterator &SymExpr::symbol_iterator::operator++() {
126  assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
127  expand();
128  return *this;
129 }
130 
131 SymbolRef SymExpr::symbol_iterator::operator*() {
132  assert(!itr.empty() && "attempting to dereference an 'end' iterator");
133  return itr.back();
134 }
135 
136 void SymExpr::symbol_iterator::expand() {
137  const SymExpr *SE = itr.pop_back_val();
138 
139  switch (SE->getKind()) {
140  case SymExpr::SymbolRegionValueKind:
141  case SymExpr::SymbolConjuredKind:
142  case SymExpr::SymbolDerivedKind:
143  case SymExpr::SymbolExtentKind:
144  case SymExpr::SymbolMetadataKind:
145  return;
146  case SymExpr::SymbolCastKind:
147  itr.push_back(cast<SymbolCast>(SE)->getOperand());
148  return;
149  case SymExpr::SymIntExprKind:
150  itr.push_back(cast<SymIntExpr>(SE)->getLHS());
151  return;
152  case SymExpr::IntSymExprKind:
153  itr.push_back(cast<IntSymExpr>(SE)->getRHS());
154  return;
155  case SymExpr::SymSymExprKind: {
156  const auto *x = cast<SymSymExpr>(SE);
157  itr.push_back(x->getLHS());
158  itr.push_back(x->getRHS());
159  return;
160  }
161  }
162  llvm_unreachable("unhandled expansion case");
163 }
164 
165 const SymbolRegionValue*
166 SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
167  llvm::FoldingSetNodeID profile;
168  SymbolRegionValue::Profile(profile, R);
169  void *InsertPos;
170  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
171  if (!SD) {
172  SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
173  new (SD) SymbolRegionValue(SymbolCounter, R);
174  DataSet.InsertNode(SD, InsertPos);
175  ++SymbolCounter;
176  }
177 
178  return cast<SymbolRegionValue>(SD);
179 }
180 
181 const SymbolConjured* SymbolManager::conjureSymbol(const Stmt *E,
182  const LocationContext *LCtx,
183  QualType T,
184  unsigned Count,
185  const void *SymbolTag) {
186  llvm::FoldingSetNodeID profile;
187  SymbolConjured::Profile(profile, E, T, Count, LCtx, SymbolTag);
188  void *InsertPos;
189  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
190  if (!SD) {
191  SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
192  new (SD) SymbolConjured(SymbolCounter, E, LCtx, T, Count, SymbolTag);
193  DataSet.InsertNode(SD, InsertPos);
194  ++SymbolCounter;
195  }
196 
197  return cast<SymbolConjured>(SD);
198 }
199 
200 const SymbolDerived*
201 SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
202  const TypedValueRegion *R) {
203  llvm::FoldingSetNodeID profile;
204  SymbolDerived::Profile(profile, parentSymbol, R);
205  void *InsertPos;
206  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
207  if (!SD) {
208  SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
209  new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
210  DataSet.InsertNode(SD, InsertPos);
211  ++SymbolCounter;
212  }
213 
214  return cast<SymbolDerived>(SD);
215 }
216 
217 const SymbolExtent*
218 SymbolManager::getExtentSymbol(const SubRegion *R) {
219  llvm::FoldingSetNodeID profile;
220  SymbolExtent::Profile(profile, R);
221  void *InsertPos;
222  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
223  if (!SD) {
224  SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
225  new (SD) SymbolExtent(SymbolCounter, R);
226  DataSet.InsertNode(SD, InsertPos);
227  ++SymbolCounter;
228  }
229 
230  return cast<SymbolExtent>(SD);
231 }
232 
233 const SymbolMetadata *
234 SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
235  const LocationContext *LCtx,
236  unsigned Count, const void *SymbolTag) {
237  llvm::FoldingSetNodeID profile;
238  SymbolMetadata::Profile(profile, R, S, T, LCtx, Count, SymbolTag);
239  void *InsertPos;
240  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
241  if (!SD) {
242  SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
243  new (SD) SymbolMetadata(SymbolCounter, R, S, T, LCtx, Count, SymbolTag);
244  DataSet.InsertNode(SD, InsertPos);
245  ++SymbolCounter;
246  }
247 
248  return cast<SymbolMetadata>(SD);
249 }
250 
251 const SymbolCast*
252 SymbolManager::getCastSymbol(const SymExpr *Op,
253  QualType From, QualType To) {
254  llvm::FoldingSetNodeID ID;
255  SymbolCast::Profile(ID, Op, From, To);
256  void *InsertPos;
257  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
258  if (!data) {
259  data = (SymbolCast*) BPAlloc.Allocate<SymbolCast>();
260  new (data) SymbolCast(Op, From, To);
261  DataSet.InsertNode(data, InsertPos);
262  }
263 
264  return cast<SymbolCast>(data);
265 }
266 
267 const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
268  BinaryOperator::Opcode op,
269  const llvm::APSInt& v,
270  QualType t) {
271  llvm::FoldingSetNodeID ID;
272  SymIntExpr::Profile(ID, lhs, op, v, t);
273  void *InsertPos;
274  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
275 
276  if (!data) {
277  data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
278  new (data) SymIntExpr(lhs, op, v, t);
279  DataSet.InsertNode(data, InsertPos);
280  }
281 
282  return cast<SymIntExpr>(data);
283 }
284 
285 const IntSymExpr *SymbolManager::getIntSymExpr(const llvm::APSInt& lhs,
286  BinaryOperator::Opcode op,
287  const SymExpr *rhs,
288  QualType t) {
289  llvm::FoldingSetNodeID ID;
290  IntSymExpr::Profile(ID, lhs, op, rhs, t);
291  void *InsertPos;
292  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
293 
294  if (!data) {
295  data = (IntSymExpr*) BPAlloc.Allocate<IntSymExpr>();
296  new (data) IntSymExpr(lhs, op, rhs, t);
297  DataSet.InsertNode(data, InsertPos);
298  }
299 
300  return cast<IntSymExpr>(data);
301 }
302 
303 const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
304  BinaryOperator::Opcode op,
305  const SymExpr *rhs,
306  QualType t) {
307  llvm::FoldingSetNodeID ID;
308  SymSymExpr::Profile(ID, lhs, op, rhs, t);
309  void *InsertPos;
310  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
311 
312  if (!data) {
313  data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
314  new (data) SymSymExpr(lhs, op, rhs, t);
315  DataSet.InsertNode(data, InsertPos);
316  }
317 
318  return cast<SymSymExpr>(data);
319 }
320 
321 QualType SymbolConjured::getType() const {
322  return T;
323 }
324 
325 QualType SymbolDerived::getType() const {
326  return R->getValueType();
327 }
328 
329 QualType SymbolExtent::getType() const {
330  ASTContext &Ctx = R->getMemRegionManager()->getContext();
331  return Ctx.getSizeType();
332 }
333 
334 QualType SymbolMetadata::getType() const {
335  return T;
336 }
337 
338 QualType SymbolRegionValue::getType() const {
339  return R->getValueType();
340 }
341 
342 SymbolManager::~SymbolManager() {
343  llvm::DeleteContainerSeconds(SymbolDependencies);
344 }
345 
346 bool SymbolManager::canSymbolicate(QualType T) {
347  T = T.getCanonicalType();
348 
349  if (Loc::isLocType(T))
350  return true;
351 
352  if (T->isIntegralOrEnumerationType())
353  return true;
354 
355  if (T->isRecordType() && !T->isUnionType())
356  return true;
357 
358  return false;
359 }
360 
361 void SymbolManager::addSymbolDependency(const SymbolRef Primary,
362  const SymbolRef Dependent) {
363  SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
364  SymbolRefSmallVectorTy *dependencies = nullptr;
365  if (I == SymbolDependencies.end()) {
366  dependencies = new SymbolRefSmallVectorTy();
367  SymbolDependencies[Primary] = dependencies;
368  } else {
369  dependencies = I->second;
370  }
371  dependencies->push_back(Dependent);
372 }
373 
374 const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
375  const SymbolRef Primary) {
376  SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
377  if (I == SymbolDependencies.end())
378  return nullptr;
379  return I->second;
380 }
381 
382 void SymbolReaper::markDependentsLive(SymbolRef sym) {
383  // Do not mark dependents more then once.
384  SymbolMapTy::iterator LI = TheLiving.find(sym);
385  assert(LI != TheLiving.end() && "The primary symbol is not live.");
386  if (LI->second == HaveMarkedDependents)
387  return;
388  LI->second = HaveMarkedDependents;
389 
390  if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
391  for (const auto I : *Deps) {
392  if (TheLiving.find(I) != TheLiving.end())
393  continue;
394  markLive(I);
395  }
396  }
397 }
398 
399 void SymbolReaper::markLive(SymbolRef sym) {
400  TheLiving[sym] = NotProcessed;
401  TheDead.erase(sym);
402  markDependentsLive(sym);
403 }
404 
405 void SymbolReaper::markLive(const MemRegion *region) {
406  RegionRoots.insert(region);
407  markElementIndicesLive(region);
408 }
409 
410 void SymbolReaper::markElementIndicesLive(const MemRegion *region) {
411  for (auto SR = dyn_cast<SubRegion>(region); SR;
412  SR = dyn_cast<SubRegion>(SR->getSuperRegion())) {
413  if (const auto ER = dyn_cast<ElementRegion>(SR)) {
414  SVal Idx = ER->getIndex();
415  for (auto SI = Idx.symbol_begin(), SE = Idx.symbol_end(); SI != SE; ++SI)
416  markLive(*SI);
417  }
418  }
419 }
420 
421 void SymbolReaper::markInUse(SymbolRef sym) {
422  if (isa<SymbolMetadata>(sym))
423  MetadataInUse.insert(sym);
424 }
425 
426 bool SymbolReaper::maybeDead(SymbolRef sym) {
427  if (isLive(sym))
428  return false;
429 
430  TheDead.insert(sym);
431  return true;
432 }
433 
434 bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
435  if (RegionRoots.count(MR))
436  return true;
437 
438  MR = MR->getBaseRegion();
439 
440  if (const auto *SR = dyn_cast<SymbolicRegion>(MR))
441  return isLive(SR->getSymbol());
442 
443  if (const auto *VR = dyn_cast<VarRegion>(MR))
444  return isLive(VR, true);
445 
446  // FIXME: This is a gross over-approximation. What we really need is a way to
447  // tell if anything still refers to this region. Unlike SymbolicRegions,
448  // AllocaRegions don't have associated symbols, though, so we don't actually
449  // have a way to track their liveness.
450  if (isa<AllocaRegion>(MR))
451  return true;
452 
453  if (isa<CXXThisRegion>(MR))
454  return true;
455 
456  if (isa<MemSpaceRegion>(MR))
457  return true;
458 
459  if (isa<CodeTextRegion>(MR))
460  return true;
461 
462  return false;
463 }
464 
465 bool SymbolReaper::isLive(SymbolRef sym) {
466  if (TheLiving.count(sym)) {
467  markDependentsLive(sym);
468  return true;
469  }
470 
471  bool KnownLive;
472 
473  switch (sym->getKind()) {
474  case SymExpr::SymbolRegionValueKind:
475  KnownLive = isLiveRegion(cast<SymbolRegionValue>(sym)->getRegion());
476  break;
477  case SymExpr::SymbolConjuredKind:
478  KnownLive = false;
479  break;
480  case SymExpr::SymbolDerivedKind:
481  KnownLive = isLive(cast<SymbolDerived>(sym)->getParentSymbol());
482  break;
483  case SymExpr::SymbolExtentKind:
484  KnownLive = isLiveRegion(cast<SymbolExtent>(sym)->getRegion());
485  break;
486  case SymExpr::SymbolMetadataKind:
487  KnownLive = MetadataInUse.count(sym) &&
488  isLiveRegion(cast<SymbolMetadata>(sym)->getRegion());
489  if (KnownLive)
490  MetadataInUse.erase(sym);
491  break;
492  case SymExpr::SymIntExprKind:
493  KnownLive = isLive(cast<SymIntExpr>(sym)->getLHS());
494  break;
495  case SymExpr::IntSymExprKind:
496  KnownLive = isLive(cast<IntSymExpr>(sym)->getRHS());
497  break;
498  case SymExpr::SymSymExprKind:
499  KnownLive = isLive(cast<SymSymExpr>(sym)->getLHS()) &&
500  isLive(cast<SymSymExpr>(sym)->getRHS());
501  break;
502  case SymExpr::SymbolCastKind:
503  KnownLive = isLive(cast<SymbolCast>(sym)->getOperand());
504  break;
505  }
506 
507  if (KnownLive)
508  markLive(sym);
509 
510  return KnownLive;
511 }
512 
513 bool
514 SymbolReaper::isLive(const Stmt *ExprVal, const LocationContext *ELCtx) const {
515  if (LCtx == nullptr)
516  return false;
517 
518  if (LCtx != ELCtx) {
519  // If the reaper's location context is a parent of the expression's
520  // location context, then the expression value is now "out of scope".
521  if (LCtx->isParentOf(ELCtx))
522  return false;
523  return true;
524  }
525 
526  // If no statement is provided, everything is this and parent contexts is live.
527  if (!Loc)
528  return true;
529 
530  return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
531 }
532 
533 bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
534  const StackFrameContext *VarContext = VR->getStackFrame();
535 
536  if (!VarContext)
537  return true;
538 
539  if (!LCtx)
540  return false;
541  const StackFrameContext *CurrentContext = LCtx->getStackFrame();
542 
543  if (VarContext == CurrentContext) {
544  // If no statement is provided, everything is live.
545  if (!Loc)
546  return true;
547 
548  if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
549  return true;
550 
551  if (!includeStoreBindings)
552  return false;
553 
554  unsigned &cachedQuery =
555  const_cast<SymbolReaper *>(this)->includedRegionCache[VR];
556 
557  if (cachedQuery) {
558  return cachedQuery == 1;
559  }
560 
561  // Query the store to see if the region occurs in any live bindings.
562  if (Store store = reapedStore.getStore()) {
563  bool hasRegion =
564  reapedStore.getStoreManager().includedInBindings(store, VR);
565  cachedQuery = hasRegion ? 1 : 2;
566  return hasRegion;
567  }
568 
569  return false;
570  }
571 
572  return VarContext->isParentOf(CurrentContext);
573 }
Defines the clang::ASTContext interface.
void dumpToStream(raw_ostream &os) const override
virtual void dump() const
void dumpToStream(raw_ostream &os) const override
StringRef getOpcodeStr() const
Definition: Expr.h:3167
virtual void dumpToStream(raw_ostream &os) const
Definition: SymExpr.h:61
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
virtual QualType getType() const =0
void dumpToStream(raw_ostream &os) const override
void dumpToStream(raw_ostream &os) const override
Dataflow Directional Tag Classes.
BinaryOperator::Opcode getOpcode(const SymExpr *SE)
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:975
void dumpToStream(raw_ostream &os) const override
void dumpToStream(raw_ostream &os) const override
void dumpToStream(raw_ostream &os) const override
void dumpToStream(raw_ostream &os) const override
void dumpToStream(raw_ostream &os) const override