clang  7.0.0svn
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 unsigned SymExpr::computeComplexity() const {
163  unsigned R = 0;
164  for (symbol_iterator I = symbol_begin(), E = symbol_end(); I != E; ++I)
165  R++;
166  return R;
167 }
168 
169 const SymbolRegionValue*
170 SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
171  llvm::FoldingSetNodeID profile;
172  SymbolRegionValue::Profile(profile, R);
173  void *InsertPos;
174  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
175  if (!SD) {
176  SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
177  new (SD) SymbolRegionValue(SymbolCounter, R);
178  DataSet.InsertNode(SD, InsertPos);
179  ++SymbolCounter;
180  }
181 
182  return cast<SymbolRegionValue>(SD);
183 }
184 
185 const SymbolConjured* SymbolManager::conjureSymbol(const Stmt *E,
186  const LocationContext *LCtx,
187  QualType T,
188  unsigned Count,
189  const void *SymbolTag) {
190  llvm::FoldingSetNodeID profile;
191  SymbolConjured::Profile(profile, E, T, Count, LCtx, SymbolTag);
192  void *InsertPos;
193  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
194  if (!SD) {
195  SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
196  new (SD) SymbolConjured(SymbolCounter, E, LCtx, T, Count, SymbolTag);
197  DataSet.InsertNode(SD, InsertPos);
198  ++SymbolCounter;
199  }
200 
201  return cast<SymbolConjured>(SD);
202 }
203 
204 const SymbolDerived*
205 SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
206  const TypedValueRegion *R) {
207  llvm::FoldingSetNodeID profile;
208  SymbolDerived::Profile(profile, parentSymbol, R);
209  void *InsertPos;
210  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
211  if (!SD) {
212  SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
213  new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
214  DataSet.InsertNode(SD, InsertPos);
215  ++SymbolCounter;
216  }
217 
218  return cast<SymbolDerived>(SD);
219 }
220 
221 const SymbolExtent*
222 SymbolManager::getExtentSymbol(const SubRegion *R) {
223  llvm::FoldingSetNodeID profile;
224  SymbolExtent::Profile(profile, R);
225  void *InsertPos;
226  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
227  if (!SD) {
228  SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
229  new (SD) SymbolExtent(SymbolCounter, R);
230  DataSet.InsertNode(SD, InsertPos);
231  ++SymbolCounter;
232  }
233 
234  return cast<SymbolExtent>(SD);
235 }
236 
237 const SymbolMetadata *
238 SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
239  const LocationContext *LCtx,
240  unsigned Count, const void *SymbolTag) {
241  llvm::FoldingSetNodeID profile;
242  SymbolMetadata::Profile(profile, R, S, T, LCtx, Count, SymbolTag);
243  void *InsertPos;
244  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
245  if (!SD) {
246  SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
247  new (SD) SymbolMetadata(SymbolCounter, R, S, T, LCtx, Count, SymbolTag);
248  DataSet.InsertNode(SD, InsertPos);
249  ++SymbolCounter;
250  }
251 
252  return cast<SymbolMetadata>(SD);
253 }
254 
255 const SymbolCast*
256 SymbolManager::getCastSymbol(const SymExpr *Op,
257  QualType From, QualType To) {
258  llvm::FoldingSetNodeID ID;
259  SymbolCast::Profile(ID, Op, From, To);
260  void *InsertPos;
261  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
262  if (!data) {
263  data = (SymbolCast*) BPAlloc.Allocate<SymbolCast>();
264  new (data) SymbolCast(Op, From, To);
265  DataSet.InsertNode(data, InsertPos);
266  }
267 
268  return cast<SymbolCast>(data);
269 }
270 
271 const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
272  BinaryOperator::Opcode op,
273  const llvm::APSInt& v,
274  QualType t) {
275  llvm::FoldingSetNodeID ID;
276  SymIntExpr::Profile(ID, lhs, op, v, t);
277  void *InsertPos;
278  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
279 
280  if (!data) {
281  data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
282  new (data) SymIntExpr(lhs, op, v, t);
283  DataSet.InsertNode(data, InsertPos);
284  }
285 
286  return cast<SymIntExpr>(data);
287 }
288 
289 const IntSymExpr *SymbolManager::getIntSymExpr(const llvm::APSInt& lhs,
290  BinaryOperator::Opcode op,
291  const SymExpr *rhs,
292  QualType t) {
293  llvm::FoldingSetNodeID ID;
294  IntSymExpr::Profile(ID, lhs, op, rhs, t);
295  void *InsertPos;
296  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
297 
298  if (!data) {
299  data = (IntSymExpr*) BPAlloc.Allocate<IntSymExpr>();
300  new (data) IntSymExpr(lhs, op, rhs, t);
301  DataSet.InsertNode(data, InsertPos);
302  }
303 
304  return cast<IntSymExpr>(data);
305 }
306 
307 const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
308  BinaryOperator::Opcode op,
309  const SymExpr *rhs,
310  QualType t) {
311  llvm::FoldingSetNodeID ID;
312  SymSymExpr::Profile(ID, lhs, op, rhs, t);
313  void *InsertPos;
314  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
315 
316  if (!data) {
317  data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
318  new (data) SymSymExpr(lhs, op, rhs, t);
319  DataSet.InsertNode(data, InsertPos);
320  }
321 
322  return cast<SymSymExpr>(data);
323 }
324 
325 QualType SymbolConjured::getType() const {
326  return T;
327 }
328 
329 QualType SymbolDerived::getType() const {
330  return R->getValueType();
331 }
332 
333 QualType SymbolExtent::getType() const {
334  ASTContext &Ctx = R->getMemRegionManager()->getContext();
335  return Ctx.getSizeType();
336 }
337 
338 QualType SymbolMetadata::getType() const {
339  return T;
340 }
341 
342 QualType SymbolRegionValue::getType() const {
343  return R->getValueType();
344 }
345 
346 SymbolManager::~SymbolManager() {
347  llvm::DeleteContainerSeconds(SymbolDependencies);
348 }
349 
350 bool SymbolManager::canSymbolicate(QualType T) {
351  T = T.getCanonicalType();
352 
353  if (Loc::isLocType(T))
354  return true;
355 
356  if (T->isIntegralOrEnumerationType())
357  return true;
358 
359  if (T->isRecordType() && !T->isUnionType())
360  return true;
361 
362  return false;
363 }
364 
365 void SymbolManager::addSymbolDependency(const SymbolRef Primary,
366  const SymbolRef Dependent) {
367  SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
368  SymbolRefSmallVectorTy *dependencies = nullptr;
369  if (I == SymbolDependencies.end()) {
370  dependencies = new SymbolRefSmallVectorTy();
371  SymbolDependencies[Primary] = dependencies;
372  } else {
373  dependencies = I->second;
374  }
375  dependencies->push_back(Dependent);
376 }
377 
378 const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
379  const SymbolRef Primary) {
380  SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
381  if (I == SymbolDependencies.end())
382  return nullptr;
383  return I->second;
384 }
385 
386 void SymbolReaper::markDependentsLive(SymbolRef sym) {
387  // Do not mark dependents more then once.
388  SymbolMapTy::iterator LI = TheLiving.find(sym);
389  assert(LI != TheLiving.end() && "The primary symbol is not live.");
390  if (LI->second == HaveMarkedDependents)
391  return;
392  LI->second = HaveMarkedDependents;
393 
394  if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
395  for (const auto I : *Deps) {
396  if (TheLiving.find(I) != TheLiving.end())
397  continue;
398  markLive(I);
399  }
400  }
401 }
402 
403 void SymbolReaper::markLive(SymbolRef sym) {
404  TheLiving[sym] = NotProcessed;
405  TheDead.erase(sym);
406  markDependentsLive(sym);
407 }
408 
409 void SymbolReaper::markLive(const MemRegion *region) {
410  RegionRoots.insert(region);
411  markElementIndicesLive(region);
412 }
413 
414 void SymbolReaper::markElementIndicesLive(const MemRegion *region) {
415  for (auto SR = dyn_cast<SubRegion>(region); SR;
416  SR = dyn_cast<SubRegion>(SR->getSuperRegion())) {
417  if (const auto ER = dyn_cast<ElementRegion>(SR)) {
418  SVal Idx = ER->getIndex();
419  for (auto SI = Idx.symbol_begin(), SE = Idx.symbol_end(); SI != SE; ++SI)
420  markLive(*SI);
421  }
422  }
423 }
424 
425 void SymbolReaper::markInUse(SymbolRef sym) {
426  if (isa<SymbolMetadata>(sym))
427  MetadataInUse.insert(sym);
428 }
429 
430 bool SymbolReaper::maybeDead(SymbolRef sym) {
431  if (isLive(sym))
432  return false;
433 
434  TheDead.insert(sym);
435  return true;
436 }
437 
438 bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
439  if (RegionRoots.count(MR))
440  return true;
441 
442  MR = MR->getBaseRegion();
443 
444  if (const auto *SR = dyn_cast<SymbolicRegion>(MR))
445  return isLive(SR->getSymbol());
446 
447  if (const auto *VR = dyn_cast<VarRegion>(MR))
448  return isLive(VR, true);
449 
450  // FIXME: This is a gross over-approximation. What we really need is a way to
451  // tell if anything still refers to this region. Unlike SymbolicRegions,
452  // AllocaRegions don't have associated symbols, though, so we don't actually
453  // have a way to track their liveness.
454  if (isa<AllocaRegion>(MR))
455  return true;
456 
457  if (isa<CXXThisRegion>(MR))
458  return true;
459 
460  if (isa<MemSpaceRegion>(MR))
461  return true;
462 
463  if (isa<CodeTextRegion>(MR))
464  return true;
465 
466  return false;
467 }
468 
469 bool SymbolReaper::isLive(SymbolRef sym) {
470  if (TheLiving.count(sym)) {
471  markDependentsLive(sym);
472  return true;
473  }
474 
475  bool KnownLive;
476 
477  switch (sym->getKind()) {
478  case SymExpr::SymbolRegionValueKind:
479  KnownLive = isLiveRegion(cast<SymbolRegionValue>(sym)->getRegion());
480  break;
481  case SymExpr::SymbolConjuredKind:
482  KnownLive = false;
483  break;
484  case SymExpr::SymbolDerivedKind:
485  KnownLive = isLive(cast<SymbolDerived>(sym)->getParentSymbol());
486  break;
487  case SymExpr::SymbolExtentKind:
488  KnownLive = isLiveRegion(cast<SymbolExtent>(sym)->getRegion());
489  break;
490  case SymExpr::SymbolMetadataKind:
491  KnownLive = MetadataInUse.count(sym) &&
492  isLiveRegion(cast<SymbolMetadata>(sym)->getRegion());
493  if (KnownLive)
494  MetadataInUse.erase(sym);
495  break;
496  case SymExpr::SymIntExprKind:
497  KnownLive = isLive(cast<SymIntExpr>(sym)->getLHS());
498  break;
499  case SymExpr::IntSymExprKind:
500  KnownLive = isLive(cast<IntSymExpr>(sym)->getRHS());
501  break;
502  case SymExpr::SymSymExprKind:
503  KnownLive = isLive(cast<SymSymExpr>(sym)->getLHS()) &&
504  isLive(cast<SymSymExpr>(sym)->getRHS());
505  break;
506  case SymExpr::SymbolCastKind:
507  KnownLive = isLive(cast<SymbolCast>(sym)->getOperand());
508  break;
509  }
510 
511  if (KnownLive)
512  markLive(sym);
513 
514  return KnownLive;
515 }
516 
517 bool
518 SymbolReaper::isLive(const Stmt *ExprVal, const LocationContext *ELCtx) const {
519  if (LCtx == nullptr)
520  return false;
521 
522  if (LCtx != ELCtx) {
523  // If the reaper's location context is a parent of the expression's
524  // location context, then the expression value is now "out of scope".
525  if (LCtx->isParentOf(ELCtx))
526  return false;
527  return true;
528  }
529 
530  // If no statement is provided, everything is this and parent contexts is live.
531  if (!Loc)
532  return true;
533 
534  return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
535 }
536 
537 bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
538  const StackFrameContext *VarContext = VR->getStackFrame();
539 
540  if (!VarContext)
541  return true;
542 
543  if (!LCtx)
544  return false;
545  const StackFrameContext *CurrentContext = LCtx->getCurrentStackFrame();
546 
547  if (VarContext == CurrentContext) {
548  // If no statement is provided, everything is live.
549  if (!Loc)
550  return true;
551 
552  if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
553  return true;
554 
555  if (!includeStoreBindings)
556  return false;
557 
558  unsigned &cachedQuery =
559  const_cast<SymbolReaper *>(this)->includedRegionCache[VR];
560 
561  if (cachedQuery) {
562  return cachedQuery == 1;
563  }
564 
565  // Query the store to see if the region occurs in any live bindings.
566  if (Store store = reapedStore.getStore()) {
567  bool hasRegion =
568  reapedStore.getStoreManager().includedInBindings(store, VR);
569  cachedQuery = hasRegion ? 1 : 2;
570  return hasRegion;
571  }
572 
573  return false;
574  }
575 
576  return VarContext->isParentOf(CurrentContext);
577 }
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:3125
virtual void dumpToStream(raw_ostream &os) const
Definition: SymExpr.h:59
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
virtual QualType getType() const =0
const FunctionProtoType * T
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:981
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