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_$" << getSymbolID() << '{' << T.getAsString() << '}';
87 }
88 
89 void SymbolDerived::dumpToStream(raw_ostream &os) const {
90  os << "derived_$" << getSymbolID() << '{'
91  << getParentSymbol() << ',' << getRegion() << '}';
92 }
93 
94 void SymbolExtent::dumpToStream(raw_ostream &os) const {
95  os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
96 }
97 
98 void SymbolMetadata::dumpToStream(raw_ostream &os) const {
99  os << "meta_$" << getSymbolID() << '{'
100  << getRegion() << ',' << T.getAsString() << '}';
101 }
102 
103 void SymbolData::anchor() {}
104 
105 void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
106  os << "reg_$" << getSymbolID()
107  << '<' << getType().getAsString() << ' ' << R << '>';
108 }
109 
110 bool SymExpr::symbol_iterator::operator==(const symbol_iterator &X) const {
111  return itr == X.itr;
112 }
113 
114 bool SymExpr::symbol_iterator::operator!=(const symbol_iterator &X) const {
115  return itr != X.itr;
116 }
117 
118 SymExpr::symbol_iterator::symbol_iterator(const SymExpr *SE) {
119  itr.push_back(SE);
120 }
121 
122 SymExpr::symbol_iterator &SymExpr::symbol_iterator::operator++() {
123  assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
124  expand();
125  return *this;
126 }
127 
128 SymbolRef SymExpr::symbol_iterator::operator*() {
129  assert(!itr.empty() && "attempting to dereference an 'end' iterator");
130  return itr.back();
131 }
132 
133 void SymExpr::symbol_iterator::expand() {
134  const SymExpr *SE = itr.pop_back_val();
135 
136  switch (SE->getKind()) {
137  case SymExpr::SymbolRegionValueKind:
138  case SymExpr::SymbolConjuredKind:
139  case SymExpr::SymbolDerivedKind:
140  case SymExpr::SymbolExtentKind:
141  case SymExpr::SymbolMetadataKind:
142  return;
143  case SymExpr::SymbolCastKind:
144  itr.push_back(cast<SymbolCast>(SE)->getOperand());
145  return;
146  case SymExpr::SymIntExprKind:
147  itr.push_back(cast<SymIntExpr>(SE)->getLHS());
148  return;
149  case SymExpr::IntSymExprKind:
150  itr.push_back(cast<IntSymExpr>(SE)->getRHS());
151  return;
152  case SymExpr::SymSymExprKind: {
153  const auto *x = cast<SymSymExpr>(SE);
154  itr.push_back(x->getLHS());
155  itr.push_back(x->getRHS());
156  return;
157  }
158  }
159  llvm_unreachable("unhandled expansion case");
160 }
161 
162 const SymbolRegionValue*
163 SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
164  llvm::FoldingSetNodeID profile;
165  SymbolRegionValue::Profile(profile, R);
166  void *InsertPos;
167  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
168  if (!SD) {
169  SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
170  new (SD) SymbolRegionValue(SymbolCounter, R);
171  DataSet.InsertNode(SD, InsertPos);
172  ++SymbolCounter;
173  }
174 
175  return cast<SymbolRegionValue>(SD);
176 }
177 
178 const SymbolConjured* SymbolManager::conjureSymbol(const Stmt *E,
179  const LocationContext *LCtx,
180  QualType T,
181  unsigned Count,
182  const void *SymbolTag) {
183  llvm::FoldingSetNodeID profile;
184  SymbolConjured::Profile(profile, E, T, Count, LCtx, SymbolTag);
185  void *InsertPos;
186  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
187  if (!SD) {
188  SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
189  new (SD) SymbolConjured(SymbolCounter, E, LCtx, T, Count, SymbolTag);
190  DataSet.InsertNode(SD, InsertPos);
191  ++SymbolCounter;
192  }
193 
194  return cast<SymbolConjured>(SD);
195 }
196 
197 const SymbolDerived*
198 SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
199  const TypedValueRegion *R) {
200  llvm::FoldingSetNodeID profile;
201  SymbolDerived::Profile(profile, parentSymbol, R);
202  void *InsertPos;
203  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
204  if (!SD) {
205  SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
206  new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
207  DataSet.InsertNode(SD, InsertPos);
208  ++SymbolCounter;
209  }
210 
211  return cast<SymbolDerived>(SD);
212 }
213 
214 const SymbolExtent*
215 SymbolManager::getExtentSymbol(const SubRegion *R) {
216  llvm::FoldingSetNodeID profile;
217  SymbolExtent::Profile(profile, R);
218  void *InsertPos;
219  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
220  if (!SD) {
221  SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
222  new (SD) SymbolExtent(SymbolCounter, R);
223  DataSet.InsertNode(SD, InsertPos);
224  ++SymbolCounter;
225  }
226 
227  return cast<SymbolExtent>(SD);
228 }
229 
230 const SymbolMetadata *
231 SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
232  const LocationContext *LCtx,
233  unsigned Count, const void *SymbolTag) {
234  llvm::FoldingSetNodeID profile;
235  SymbolMetadata::Profile(profile, R, S, T, LCtx, Count, SymbolTag);
236  void *InsertPos;
237  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
238  if (!SD) {
239  SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
240  new (SD) SymbolMetadata(SymbolCounter, R, S, T, LCtx, Count, SymbolTag);
241  DataSet.InsertNode(SD, InsertPos);
242  ++SymbolCounter;
243  }
244 
245  return cast<SymbolMetadata>(SD);
246 }
247 
248 const SymbolCast*
249 SymbolManager::getCastSymbol(const SymExpr *Op,
250  QualType From, QualType To) {
251  llvm::FoldingSetNodeID ID;
252  SymbolCast::Profile(ID, Op, From, To);
253  void *InsertPos;
254  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
255  if (!data) {
256  data = (SymbolCast*) BPAlloc.Allocate<SymbolCast>();
257  new (data) SymbolCast(Op, From, To);
258  DataSet.InsertNode(data, InsertPos);
259  }
260 
261  return cast<SymbolCast>(data);
262 }
263 
264 const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
265  BinaryOperator::Opcode op,
266  const llvm::APSInt& v,
267  QualType t) {
268  llvm::FoldingSetNodeID ID;
269  SymIntExpr::Profile(ID, lhs, op, v, t);
270  void *InsertPos;
271  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
272 
273  if (!data) {
274  data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
275  new (data) SymIntExpr(lhs, op, v, t);
276  DataSet.InsertNode(data, InsertPos);
277  }
278 
279  return cast<SymIntExpr>(data);
280 }
281 
282 const IntSymExpr *SymbolManager::getIntSymExpr(const llvm::APSInt& lhs,
283  BinaryOperator::Opcode op,
284  const SymExpr *rhs,
285  QualType t) {
286  llvm::FoldingSetNodeID ID;
287  IntSymExpr::Profile(ID, lhs, op, rhs, t);
288  void *InsertPos;
289  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
290 
291  if (!data) {
292  data = (IntSymExpr*) BPAlloc.Allocate<IntSymExpr>();
293  new (data) IntSymExpr(lhs, op, rhs, t);
294  DataSet.InsertNode(data, InsertPos);
295  }
296 
297  return cast<IntSymExpr>(data);
298 }
299 
300 const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
301  BinaryOperator::Opcode op,
302  const SymExpr *rhs,
303  QualType t) {
304  llvm::FoldingSetNodeID ID;
305  SymSymExpr::Profile(ID, lhs, op, rhs, t);
306  void *InsertPos;
307  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
308 
309  if (!data) {
310  data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
311  new (data) SymSymExpr(lhs, op, rhs, t);
312  DataSet.InsertNode(data, InsertPos);
313  }
314 
315  return cast<SymSymExpr>(data);
316 }
317 
318 QualType SymbolConjured::getType() const {
319  return T;
320 }
321 
322 QualType SymbolDerived::getType() const {
323  return R->getValueType();
324 }
325 
326 QualType SymbolExtent::getType() const {
327  ASTContext &Ctx = R->getMemRegionManager()->getContext();
328  return Ctx.getSizeType();
329 }
330 
331 QualType SymbolMetadata::getType() const {
332  return T;
333 }
334 
335 QualType SymbolRegionValue::getType() const {
336  return R->getValueType();
337 }
338 
339 SymbolManager::~SymbolManager() {
340  llvm::DeleteContainerSeconds(SymbolDependencies);
341 }
342 
343 bool SymbolManager::canSymbolicate(QualType T) {
344  T = T.getCanonicalType();
345 
346  if (Loc::isLocType(T))
347  return true;
348 
349  if (T->isIntegralOrEnumerationType())
350  return true;
351 
352  if (T->isRecordType() && !T->isUnionType())
353  return true;
354 
355  return false;
356 }
357 
358 void SymbolManager::addSymbolDependency(const SymbolRef Primary,
359  const SymbolRef Dependent) {
360  SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
361  SymbolRefSmallVectorTy *dependencies = nullptr;
362  if (I == SymbolDependencies.end()) {
363  dependencies = new SymbolRefSmallVectorTy();
364  SymbolDependencies[Primary] = dependencies;
365  } else {
366  dependencies = I->second;
367  }
368  dependencies->push_back(Dependent);
369 }
370 
371 const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
372  const SymbolRef Primary) {
373  SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
374  if (I == SymbolDependencies.end())
375  return nullptr;
376  return I->second;
377 }
378 
379 void SymbolReaper::markDependentsLive(SymbolRef sym) {
380  // Do not mark dependents more then once.
381  SymbolMapTy::iterator LI = TheLiving.find(sym);
382  assert(LI != TheLiving.end() && "The primary symbol is not live.");
383  if (LI->second == HaveMarkedDependents)
384  return;
385  LI->second = HaveMarkedDependents;
386 
387  if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
388  for (const auto I : *Deps) {
389  if (TheLiving.find(I) != TheLiving.end())
390  continue;
391  markLive(I);
392  }
393  }
394 }
395 
396 void SymbolReaper::markLive(SymbolRef sym) {
397  TheLiving[sym] = NotProcessed;
398  TheDead.erase(sym);
399  markDependentsLive(sym);
400 }
401 
402 void SymbolReaper::markLive(const MemRegion *region) {
403  RegionRoots.insert(region);
404  markElementIndicesLive(region);
405 }
406 
407 void SymbolReaper::markElementIndicesLive(const MemRegion *region) {
408  for (auto SR = dyn_cast<SubRegion>(region); SR;
409  SR = dyn_cast<SubRegion>(SR->getSuperRegion())) {
410  if (const auto ER = dyn_cast<ElementRegion>(SR)) {
411  SVal Idx = ER->getIndex();
412  for (auto SI = Idx.symbol_begin(), SE = Idx.symbol_end(); SI != SE; ++SI)
413  markLive(*SI);
414  }
415  }
416 }
417 
418 void SymbolReaper::markInUse(SymbolRef sym) {
419  if (isa<SymbolMetadata>(sym))
420  MetadataInUse.insert(sym);
421 }
422 
423 bool SymbolReaper::maybeDead(SymbolRef sym) {
424  if (isLive(sym))
425  return false;
426 
427  TheDead.insert(sym);
428  return true;
429 }
430 
431 bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
432  if (RegionRoots.count(MR))
433  return true;
434 
435  MR = MR->getBaseRegion();
436 
437  if (const auto *SR = dyn_cast<SymbolicRegion>(MR))
438  return isLive(SR->getSymbol());
439 
440  if (const auto *VR = dyn_cast<VarRegion>(MR))
441  return isLive(VR, true);
442 
443  // FIXME: This is a gross over-approximation. What we really need is a way to
444  // tell if anything still refers to this region. Unlike SymbolicRegions,
445  // AllocaRegions don't have associated symbols, though, so we don't actually
446  // have a way to track their liveness.
447  if (isa<AllocaRegion>(MR))
448  return true;
449 
450  if (isa<CXXThisRegion>(MR))
451  return true;
452 
453  if (isa<MemSpaceRegion>(MR))
454  return true;
455 
456  if (isa<CodeTextRegion>(MR))
457  return true;
458 
459  return false;
460 }
461 
462 bool SymbolReaper::isLive(SymbolRef sym) {
463  if (TheLiving.count(sym)) {
464  markDependentsLive(sym);
465  return true;
466  }
467 
468  bool KnownLive;
469 
470  switch (sym->getKind()) {
471  case SymExpr::SymbolRegionValueKind:
472  KnownLive = isLiveRegion(cast<SymbolRegionValue>(sym)->getRegion());
473  break;
474  case SymExpr::SymbolConjuredKind:
475  KnownLive = false;
476  break;
477  case SymExpr::SymbolDerivedKind:
478  KnownLive = isLive(cast<SymbolDerived>(sym)->getParentSymbol());
479  break;
480  case SymExpr::SymbolExtentKind:
481  KnownLive = isLiveRegion(cast<SymbolExtent>(sym)->getRegion());
482  break;
483  case SymExpr::SymbolMetadataKind:
484  KnownLive = MetadataInUse.count(sym) &&
485  isLiveRegion(cast<SymbolMetadata>(sym)->getRegion());
486  if (KnownLive)
487  MetadataInUse.erase(sym);
488  break;
489  case SymExpr::SymIntExprKind:
490  KnownLive = isLive(cast<SymIntExpr>(sym)->getLHS());
491  break;
492  case SymExpr::IntSymExprKind:
493  KnownLive = isLive(cast<IntSymExpr>(sym)->getRHS());
494  break;
495  case SymExpr::SymSymExprKind:
496  KnownLive = isLive(cast<SymSymExpr>(sym)->getLHS()) &&
497  isLive(cast<SymSymExpr>(sym)->getRHS());
498  break;
499  case SymExpr::SymbolCastKind:
500  KnownLive = isLive(cast<SymbolCast>(sym)->getOperand());
501  break;
502  }
503 
504  if (KnownLive)
505  markLive(sym);
506 
507  return KnownLive;
508 }
509 
510 bool
511 SymbolReaper::isLive(const Stmt *ExprVal, const LocationContext *ELCtx) const {
512  if (LCtx == nullptr)
513  return false;
514 
515  if (LCtx != ELCtx) {
516  // If the reaper's location context is a parent of the expression's
517  // location context, then the expression value is now "out of scope".
518  if (LCtx->isParentOf(ELCtx))
519  return false;
520  return true;
521  }
522 
523  // If no statement is provided, everything is this and parent contexts is live.
524  if (!Loc)
525  return true;
526 
527  return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
528 }
529 
530 bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
531  const StackFrameContext *VarContext = VR->getStackFrame();
532 
533  if (!VarContext)
534  return true;
535 
536  if (!LCtx)
537  return false;
538  const StackFrameContext *CurrentContext = LCtx->getStackFrame();
539 
540  if (VarContext == CurrentContext) {
541  // If no statement is provided, everything is live.
542  if (!Loc)
543  return true;
544 
545  if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
546  return true;
547 
548  if (!includeStoreBindings)
549  return false;
550 
551  unsigned &cachedQuery =
552  const_cast<SymbolReaper *>(this)->includedRegionCache[VR];
553 
554  if (cachedQuery) {
555  return cachedQuery == 1;
556  }
557 
558  // Query the store to see if the region occurs in any live bindings.
559  if (Store store = reapedStore.getStore()) {
560  bool hasRegion =
561  reapedStore.getStoreManager().includedInBindings(store, VR);
562  cachedQuery = hasRegion ? 1 : 2;
563  return hasRegion;
564  }
565 
566  return false;
567  }
568 
569  return VarContext->isParentOf(CurrentContext);
570 }
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:3331
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:973
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