SymbolManager.cpp revision 0b3ade86a1c60cf0c7b56aa238aff458eb7f5974 
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
21using namespace clang;
22using namespace ento;
23
24void SymExpr::anchor() { }
25
26void SymExpr::dump() const {
27  dumpToStream(llvm::errs());
28}
29
30static void print(raw_ostream &os, BinaryOperator::Opcode Op) {
31  switch (Op) {
32    default:
33      llvm_unreachable("operator printing not implemented");
34    case BO_Mul: os << '*'  ; break;
35    case BO_Div: os << '/'  ; break;
36    case BO_Rem: os << '%'  ; break;
37    case BO_Add: os << '+'  ; break;
38    case BO_Sub: os << '-'  ; break;
39    case BO_Shl: os << "<<" ; break;
40    case BO_Shr: os << ">>" ; break;
41    case BO_LT:  os << "<"  ; break;
42    case BO_GT:  os << '>'  ; break;
43    case BO_LE:  os << "<=" ; break;
44    case BO_GE:  os << ">=" ; break;
45    case BO_EQ:  os << "==" ; break;
46    case BO_NE:  os << "!=" ; break;
47    case BO_And: os << '&'  ; break;
48    case BO_Xor: os << '^'  ; break;
49    case BO_Or:  os << '|'  ; break;
50  }
51}
52
53void SymIntExpr::dumpToStream(raw_ostream &os) const {
54  os << '(';
55  getLHS()->dumpToStream(os);
56  os << ") ";
57  print(os, getOpcode());
58  os << ' ' << getRHS().getZExtValue();
59  if (getRHS().isUnsigned()) os << 'U';
60}
61
62void IntSymExpr::dumpToStream(raw_ostream &os) const {
63  os << ' ' << getLHS().getZExtValue();
64  if (getLHS().isUnsigned()) os << 'U';
65  print(os, getOpcode());
66  os << '(';
67  getRHS()->dumpToStream(os);
68  os << ") ";
69}
70
71void SymSymExpr::dumpToStream(raw_ostream &os) const {
72  os << '(';
73  getLHS()->dumpToStream(os);
74  os << ") ";
75  os << '(';
76  getRHS()->dumpToStream(os);
77  os << ')';
78}
79
80void SymbolCast::dumpToStream(raw_ostream &os) const {
81  os << '(' << ToTy.getAsString() << ") (";
82  Operand->dumpToStream(os);
83  os << ')';
84}
85
86void SymbolConjured::dumpToStream(raw_ostream &os) const {
87  os << "conj_$" << getSymbolID() << '{' << T.getAsString() << '}';
88}
89
90void SymbolDerived::dumpToStream(raw_ostream &os) const {
91  os << "derived_$" << getSymbolID() << '{'
92     << getParentSymbol() << ',' << getRegion() << '}';
93}
94
95void SymbolExtent::dumpToStream(raw_ostream &os) const {
96  os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
97}
98
99void SymbolMetadata::dumpToStream(raw_ostream &os) const {
100  os << "meta_$" << getSymbolID() << '{'
101     << getRegion() << ',' << T.getAsString() << '}';
102}
103
104void SymbolData::anchor() { }
105
106void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
107  os << "reg_$" << getSymbolID() << "<" << R << ">";
108}
109
110bool SymExpr::symbol_iterator::operator==(const symbol_iterator &X) const {
111  return itr == X.itr;
112}
113
114bool SymExpr::symbol_iterator::operator!=(const symbol_iterator &X) const {
115  return itr != X.itr;
116}
117
118SymExpr::symbol_iterator::symbol_iterator(const SymExpr *SE) {
119  itr.push_back(SE);
120  while (!isa<SymbolData>(itr.back())) expand();
121}
122
123SymExpr::symbol_iterator &SymExpr::symbol_iterator::operator++() {
124  assert(!itr.empty() && "attempting to iterate on an 'end' iterator");
125  assert(isa<SymbolData>(itr.back()));
126  itr.pop_back();
127  if (!itr.empty())
128    while (!isa<SymbolData>(itr.back())) expand();
129  return *this;
130}
131
132SymbolRef SymExpr::symbol_iterator::operator*() {
133  assert(!itr.empty() && "attempting to dereference an 'end' iterator");
134  return cast<SymbolData>(itr.back());
135}
136
137void SymExpr::symbol_iterator::expand() {
138  const SymExpr *SE = itr.back();
139  itr.pop_back();
140
141  switch (SE->getKind()) {
142    case SymExpr::RegionValueKind:
143    case SymExpr::ConjuredKind:
144    case SymExpr::DerivedKind:
145    case SymExpr::ExtentKind:
146    case SymExpr::MetadataKind:
147      return;
148    case SymExpr::CastSymbolKind:
149      itr.push_back(cast<SymbolCast>(SE)->getOperand());
150      return;
151    case SymExpr::SymIntKind:
152      itr.push_back(cast<SymIntExpr>(SE)->getLHS());
153      return;
154    case SymExpr::IntSymKind:
155      itr.push_back(cast<IntSymExpr>(SE)->getRHS());
156      return;
157    case SymExpr::SymSymKind: {
158      const SymSymExpr *x = cast<SymSymExpr>(SE);
159      itr.push_back(x->getLHS());
160      itr.push_back(x->getRHS());
161      return;
162    }
163  }
164  llvm_unreachable("unhandled expansion case");
165}
166
167const SymbolRegionValue*
168SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
169  llvm::FoldingSetNodeID profile;
170  SymbolRegionValue::Profile(profile, R);
171  void *InsertPos;
172  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
173  if (!SD) {
174    SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
175    new (SD) SymbolRegionValue(SymbolCounter, R);
176    DataSet.InsertNode(SD, InsertPos);
177    ++SymbolCounter;
178  }
179
180  return cast<SymbolRegionValue>(SD);
181}
182
183const SymbolConjured*
184SymbolManager::getConjuredSymbol(const Stmt *E, const LocationContext *LCtx,
185                                 QualType T, unsigned Count,
186                                 const void *SymbolTag) {
187
188  llvm::FoldingSetNodeID profile;
189  SymbolConjured::Profile(profile, E, T, Count, LCtx, SymbolTag);
190  void *InsertPos;
191  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
192  if (!SD) {
193    SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
194    new (SD) SymbolConjured(SymbolCounter, E, LCtx, T, Count, SymbolTag);
195    DataSet.InsertNode(SD, InsertPos);
196    ++SymbolCounter;
197  }
198
199  return cast<SymbolConjured>(SD);
200}
201
202const SymbolDerived*
203SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
204                                const TypedValueRegion *R) {
205
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
220const SymbolExtent*
221SymbolManager::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
236const SymbolMetadata*
237SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
238                                 unsigned Count, const void *SymbolTag) {
239
240  llvm::FoldingSetNodeID profile;
241  SymbolMetadata::Profile(profile, R, S, T, 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, Count, SymbolTag);
247    DataSet.InsertNode(SD, InsertPos);
248    ++SymbolCounter;
249  }
250
251  return cast<SymbolMetadata>(SD);
252}
253
254const SymbolCast*
255SymbolManager::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
270const 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
288const 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
306const 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
324QualType SymbolConjured::getType(ASTContext&) const {
325  return T;
326}
327
328QualType SymbolDerived::getType(ASTContext &Ctx) const {
329  return R->getValueType();
330}
331
332QualType SymbolExtent::getType(ASTContext &Ctx) const {
333  return Ctx.getSizeType();
334}
335
336QualType SymbolMetadata::getType(ASTContext&) const {
337  return T;
338}
339
340QualType SymbolRegionValue::getType(ASTContext &C) const {
341  return R->getValueType();
342}
343
344SymbolManager::~SymbolManager() {
345  for (SymbolDependTy::const_iterator I = SymbolDependencies.begin(),
346       E = SymbolDependencies.end(); I != E; ++I) {
347    delete I->second;
348  }
349
350}
351
352bool SymbolManager::canSymbolicate(QualType T) {
353  T = T.getCanonicalType();
354
355  if (Loc::isLocType(T))
356    return true;
357
358  if (T->isIntegerType())
359    return T->isScalarType();
360
361  if (T->isRecordType() && !T->isUnionType())
362    return true;
363
364  return false;
365}
366
367void SymbolManager::addSymbolDependency(const SymbolRef Primary,
368                                        const SymbolRef Dependent) {
369  SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
370  SymbolRefSmallVectorTy *dependencies = 0;
371  if (I == SymbolDependencies.end()) {
372    dependencies = new SymbolRefSmallVectorTy();
373    SymbolDependencies[Primary] = dependencies;
374  } else {
375    dependencies = I->second;
376  }
377  dependencies->push_back(Dependent);
378}
379
380const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
381                                                     const SymbolRef Primary) {
382  SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
383  if (I == SymbolDependencies.end())
384    return 0;
385  return I->second;
386}
387
388void SymbolReaper::markDependentsLive(SymbolRef sym) {
389  // Do not mark dependents more then once.
390  SymbolMapTy::iterator LI = TheLiving.find(sym);
391  assert(LI != TheLiving.end() && "The primary symbol is not live.");
392  if (LI->second == HaveMarkedDependents)
393    return;
394  LI->second = HaveMarkedDependents;
395
396  if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
397    for (SymbolRefSmallVectorTy::const_iterator I = Deps->begin(),
398                                                E = Deps->end(); I != E; ++I) {
399      if (TheLiving.find(*I) != TheLiving.end())
400        continue;
401      markLive(*I);
402    }
403  }
404}
405
406void SymbolReaper::markLive(SymbolRef sym) {
407  TheLiving[sym] = NotProcessed;
408  TheDead.erase(sym);
409  markDependentsLive(sym);
410}
411
412void SymbolReaper::markLive(const MemRegion *region) {
413  RegionRoots.insert(region);
414}
415
416void SymbolReaper::markInUse(SymbolRef sym) {
417  if (isa<SymbolMetadata>(sym))
418    MetadataInUse.insert(sym);
419}
420
421bool SymbolReaper::maybeDead(SymbolRef sym) {
422  if (isLive(sym))
423    return false;
424
425  TheDead.insert(sym);
426  return true;
427}
428
429bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
430  if (RegionRoots.count(MR))
431    return true;
432
433  MR = MR->getBaseRegion();
434
435  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR))
436    return isLive(SR->getSymbol());
437
438  if (const VarRegion *VR = dyn_cast<VarRegion>(MR))
439    return isLive(VR, true);
440
441  // FIXME: This is a gross over-approximation. What we really need is a way to
442  // tell if anything still refers to this region. Unlike SymbolicRegions,
443  // AllocaRegions don't have associated symbols, though, so we don't actually
444  // have a way to track their liveness.
445  if (isa<AllocaRegion>(MR))
446    return true;
447
448  if (isa<CXXThisRegion>(MR))
449    return true;
450
451  if (isa<MemSpaceRegion>(MR))
452    return true;
453
454  return false;
455}
456
457bool SymbolReaper::isLive(SymbolRef sym) {
458  if (TheLiving.count(sym)) {
459    markDependentsLive(sym);
460    return true;
461  }
462
463  if (const SymbolDerived *derived = dyn_cast<SymbolDerived>(sym)) {
464    if (isLive(derived->getParentSymbol())) {
465      markLive(sym);
466      return true;
467    }
468    return false;
469  }
470
471  if (const SymbolExtent *extent = dyn_cast<SymbolExtent>(sym)) {
472    if (isLiveRegion(extent->getRegion())) {
473      markLive(sym);
474      return true;
475    }
476    return false;
477  }
478
479  if (const SymbolMetadata *metadata = dyn_cast<SymbolMetadata>(sym)) {
480    if (MetadataInUse.count(sym)) {
481      if (isLiveRegion(metadata->getRegion())) {
482        markLive(sym);
483        MetadataInUse.erase(sym);
484        return true;
485      }
486    }
487    return false;
488  }
489
490  // Interogate the symbol.  It may derive from an input value to
491  // the analyzed function/method.
492  return isa<SymbolRegionValue>(sym);
493}
494
495bool
496SymbolReaper::isLive(const Stmt *ExprVal, const LocationContext *ELCtx) const {
497  if (LCtx != ELCtx) {
498    // If the reaper's location context is a parent of the expression's
499    // location context, then the expression value is now "out of scope".
500    if (LCtx->isParentOf(ELCtx))
501      return false;
502    return true;
503  }
504  // If no statement is provided, everything is this and parent contexts is live.
505  if (!Loc)
506    return true;
507
508  return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
509}
510
511bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
512  const StackFrameContext *VarContext = VR->getStackFrame();
513  const StackFrameContext *CurrentContext = LCtx->getCurrentStackFrame();
514
515  if (VarContext == CurrentContext) {
516    // If no statemetnt is provided, everything is live.
517    if (!Loc)
518      return true;
519
520    if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
521      return true;
522
523    if (!includeStoreBindings)
524      return false;
525
526    unsigned &cachedQuery =
527      const_cast<SymbolReaper*>(this)->includedRegionCache[VR];
528
529    if (cachedQuery) {
530      return cachedQuery == 1;
531    }
532
533    // Query the store to see if the region occurs in any live bindings.
534    if (Store store = reapedStore.getStore()) {
535      bool hasRegion =
536        reapedStore.getStoreManager().includedInBindings(store, VR);
537      cachedQuery = hasRegion ? 1 : 2;
538      return hasRegion;
539    }
540
541    return false;
542  }
543
544  return VarContext->isParentOf(CurrentContext);
545}
546
547SymbolVisitor::~SymbolVisitor() {}
548