SymbolManager.cpp revision a5937bbfd19e61d651a58b0f0ffeef68457902a5 
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::dump() const {
25  dumpToStream(llvm::errs());
26}
27
28static void print(raw_ostream &os, BinaryOperator::Opcode Op) {
29  switch (Op) {
30    default:
31      llvm_unreachable("operator printing not implemented");
32    case BO_Mul: os << '*'  ; break;
33    case BO_Div: os << '/'  ; break;
34    case BO_Rem: os << '%'  ; break;
35    case BO_Add: os << '+'  ; break;
36    case BO_Sub: os << '-'  ; break;
37    case BO_Shl: os << "<<" ; break;
38    case BO_Shr: os << ">>" ; break;
39    case BO_LT:  os << "<"  ; break;
40    case BO_GT:  os << '>'  ; break;
41    case BO_LE:  os << "<=" ; break;
42    case BO_GE:  os << ">=" ; break;
43    case BO_EQ:  os << "==" ; break;
44    case BO_NE:  os << "!=" ; break;
45    case BO_And: os << '&'  ; break;
46    case BO_Xor: os << '^'  ; break;
47    case BO_Or:  os << '|'  ; break;
48  }
49}
50
51void SymIntExpr::dumpToStream(raw_ostream &os) const {
52  os << '(';
53  getLHS()->dumpToStream(os);
54  os << ") ";
55  print(os, getOpcode());
56  os << ' ' << getRHS().getZExtValue();
57  if (getRHS().isUnsigned()) os << 'U';
58}
59
60void SymSymExpr::dumpToStream(raw_ostream &os) const {
61  os << '(';
62  getLHS()->dumpToStream(os);
63  os << ") ";
64  os << '(';
65  getRHS()->dumpToStream(os);
66  os << ')';
67}
68
69void SymbolConjured::dumpToStream(raw_ostream &os) const {
70  os << "conj_$" << getSymbolID() << '{' << T.getAsString() << '}';
71}
72
73void SymbolDerived::dumpToStream(raw_ostream &os) const {
74  os << "derived_$" << getSymbolID() << '{'
75     << getParentSymbol() << ',' << getRegion() << '}';
76}
77
78void SymbolExtent::dumpToStream(raw_ostream &os) const {
79  os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
80}
81
82void SymbolMetadata::dumpToStream(raw_ostream &os) const {
83  os << "meta_$" << getSymbolID() << '{'
84     << getRegion() << ',' << T.getAsString() << '}';
85}
86
87void SymbolRegionValue::dumpToStream(raw_ostream &os) const {
88  os << "reg_$" << getSymbolID() << "<" << R << ">";
89}
90
91const SymbolRegionValue*
92SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
93  llvm::FoldingSetNodeID profile;
94  SymbolRegionValue::Profile(profile, R);
95  void *InsertPos;
96  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
97  if (!SD) {
98    SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
99    new (SD) SymbolRegionValue(SymbolCounter, R);
100    DataSet.InsertNode(SD, InsertPos);
101    ++SymbolCounter;
102  }
103
104  return cast<SymbolRegionValue>(SD);
105}
106
107const SymbolConjured*
108SymbolManager::getConjuredSymbol(const Stmt *E, QualType T, unsigned Count,
109                                 const void *SymbolTag) {
110
111  llvm::FoldingSetNodeID profile;
112  SymbolConjured::Profile(profile, E, T, Count, SymbolTag);
113  void *InsertPos;
114  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
115  if (!SD) {
116    SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
117    new (SD) SymbolConjured(SymbolCounter, E, T, Count, SymbolTag);
118    DataSet.InsertNode(SD, InsertPos);
119    ++SymbolCounter;
120  }
121
122  return cast<SymbolConjured>(SD);
123}
124
125const SymbolDerived*
126SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
127                                const TypedValueRegion *R) {
128
129  llvm::FoldingSetNodeID profile;
130  SymbolDerived::Profile(profile, parentSymbol, R);
131  void *InsertPos;
132  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
133  if (!SD) {
134    SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
135    new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
136    DataSet.InsertNode(SD, InsertPos);
137    ++SymbolCounter;
138  }
139
140  return cast<SymbolDerived>(SD);
141}
142
143const SymbolExtent*
144SymbolManager::getExtentSymbol(const SubRegion *R) {
145  llvm::FoldingSetNodeID profile;
146  SymbolExtent::Profile(profile, R);
147  void *InsertPos;
148  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
149  if (!SD) {
150    SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
151    new (SD) SymbolExtent(SymbolCounter, R);
152    DataSet.InsertNode(SD, InsertPos);
153    ++SymbolCounter;
154  }
155
156  return cast<SymbolExtent>(SD);
157}
158
159const SymbolMetadata*
160SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt *S, QualType T,
161                                 unsigned Count, const void *SymbolTag) {
162
163  llvm::FoldingSetNodeID profile;
164  SymbolMetadata::Profile(profile, R, S, T, Count, SymbolTag);
165  void *InsertPos;
166  SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
167  if (!SD) {
168    SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
169    new (SD) SymbolMetadata(SymbolCounter, R, S, T, Count, SymbolTag);
170    DataSet.InsertNode(SD, InsertPos);
171    ++SymbolCounter;
172  }
173
174  return cast<SymbolMetadata>(SD);
175}
176
177const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
178                                               BinaryOperator::Opcode op,
179                                               const llvm::APSInt& v,
180                                               QualType t) {
181  llvm::FoldingSetNodeID ID;
182  SymIntExpr::Profile(ID, lhs, op, v, t);
183  void *InsertPos;
184  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
185
186  if (!data) {
187    data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
188    new (data) SymIntExpr(lhs, op, v, t);
189    DataSet.InsertNode(data, InsertPos);
190  }
191
192  return cast<SymIntExpr>(data);
193}
194
195const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
196                                               BinaryOperator::Opcode op,
197                                               const SymExpr *rhs,
198                                               QualType t) {
199  llvm::FoldingSetNodeID ID;
200  SymSymExpr::Profile(ID, lhs, op, rhs, t);
201  void *InsertPos;
202  SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
203
204  if (!data) {
205    data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
206    new (data) SymSymExpr(lhs, op, rhs, t);
207    DataSet.InsertNode(data, InsertPos);
208  }
209
210  return cast<SymSymExpr>(data);
211}
212
213QualType SymbolConjured::getType(ASTContext&) const {
214  return T;
215}
216
217QualType SymbolDerived::getType(ASTContext &Ctx) const {
218  return R->getValueType();
219}
220
221QualType SymbolExtent::getType(ASTContext &Ctx) const {
222  return Ctx.getSizeType();
223}
224
225QualType SymbolMetadata::getType(ASTContext&) const {
226  return T;
227}
228
229QualType SymbolRegionValue::getType(ASTContext &C) const {
230  return R->getValueType();
231}
232
233SymbolManager::~SymbolManager() {
234  for (SymbolDependTy::const_iterator I = SymbolDependencies.begin(),
235       E = SymbolDependencies.end(); I != E; ++I) {
236    delete I->second;
237  }
238
239}
240
241bool SymbolManager::canSymbolicate(QualType T) {
242  T = T.getCanonicalType();
243
244  if (Loc::isLocType(T))
245    return true;
246
247  if (T->isIntegerType())
248    return T->isScalarType();
249
250  if (T->isRecordType() && !T->isUnionType())
251    return true;
252
253  return false;
254}
255
256void SymbolManager::addSymbolDependency(const SymbolRef Primary,
257                                        const SymbolRef Dependent) {
258  SymbolDependTy::iterator I = SymbolDependencies.find(Primary);
259  SymbolRefSmallVectorTy *dependencies = 0;
260  if (I == SymbolDependencies.end()) {
261    dependencies = new SymbolRefSmallVectorTy();
262    SymbolDependencies[Primary] = dependencies;
263  } else {
264    dependencies = I->second;
265  }
266  dependencies->push_back(Dependent);
267}
268
269const SymbolRefSmallVectorTy *SymbolManager::getDependentSymbols(
270                                                     const SymbolRef Primary) {
271  SymbolDependTy::const_iterator I = SymbolDependencies.find(Primary);
272  if (I == SymbolDependencies.end())
273    return 0;
274  return I->second;
275}
276
277void SymbolReaper::markDependentsLive(SymbolRef sym) {
278  // Do not mark dependents more then once.
279  SymbolMapTy::iterator LI = TheLiving.find(sym);
280  assert(LI != TheLiving.end() && "The primary symbol is not live.");
281  if (LI->second == HaveMarkedDependents)
282    return;
283  LI->second = HaveMarkedDependents;
284
285  if (const SymbolRefSmallVectorTy *Deps = SymMgr.getDependentSymbols(sym)) {
286    for (SymbolRefSmallVectorTy::const_iterator I = Deps->begin(),
287                                                E = Deps->end(); I != E; ++I) {
288      if (TheLiving.find(*I) != TheLiving.end())
289        continue;
290      markLive(*I);
291    }
292  }
293}
294
295void SymbolReaper::markLive(SymbolRef sym) {
296  TheLiving[sym] = NotProcessed;
297  TheDead.erase(sym);
298  markDependentsLive(sym);
299}
300
301void SymbolReaper::markLive(const MemRegion *region) {
302  RegionRoots.insert(region);
303}
304
305void SymbolReaper::markInUse(SymbolRef sym) {
306  if (isa<SymbolMetadata>(sym))
307    MetadataInUse.insert(sym);
308}
309
310bool SymbolReaper::maybeDead(SymbolRef sym) {
311  if (isLive(sym))
312    return false;
313
314  TheDead.insert(sym);
315  return true;
316}
317
318bool SymbolReaper::isLiveRegion(const MemRegion *MR) {
319  if (RegionRoots.count(MR))
320    return true;
321
322  MR = MR->getBaseRegion();
323
324  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR))
325    return isLive(SR->getSymbol());
326
327  if (const VarRegion *VR = dyn_cast<VarRegion>(MR))
328    return isLive(VR, true);
329
330  // FIXME: This is a gross over-approximation. What we really need is a way to
331  // tell if anything still refers to this region. Unlike SymbolicRegions,
332  // AllocaRegions don't have associated symbols, though, so we don't actually
333  // have a way to track their liveness.
334  if (isa<AllocaRegion>(MR))
335    return true;
336
337  if (isa<CXXThisRegion>(MR))
338    return true;
339
340  if (isa<MemSpaceRegion>(MR))
341    return true;
342
343  return false;
344}
345
346bool SymbolReaper::isLive(SymbolRef sym) {
347  if (TheLiving.count(sym)) {
348    markDependentsLive(sym);
349    return true;
350  }
351
352  if (const SymbolDerived *derived = dyn_cast<SymbolDerived>(sym)) {
353    if (isLive(derived->getParentSymbol())) {
354      markLive(sym);
355      return true;
356    }
357    return false;
358  }
359
360  if (const SymbolExtent *extent = dyn_cast<SymbolExtent>(sym)) {
361    if (isLiveRegion(extent->getRegion())) {
362      markLive(sym);
363      return true;
364    }
365    return false;
366  }
367
368  if (const SymbolMetadata *metadata = dyn_cast<SymbolMetadata>(sym)) {
369    if (MetadataInUse.count(sym)) {
370      if (isLiveRegion(metadata->getRegion())) {
371        markLive(sym);
372        MetadataInUse.erase(sym);
373        return true;
374      }
375    }
376    return false;
377  }
378
379  // Interogate the symbol.  It may derive from an input value to
380  // the analyzed function/method.
381  return isa<SymbolRegionValue>(sym);
382}
383
384bool SymbolReaper::isLive(const Stmt *ExprVal) const {
385  return LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, ExprVal);
386}
387
388bool SymbolReaper::isLive(const VarRegion *VR, bool includeStoreBindings) const{
389  const StackFrameContext *VarContext = VR->getStackFrame();
390  const StackFrameContext *CurrentContext = LCtx->getCurrentStackFrame();
391
392  if (VarContext == CurrentContext) {
393    if (LCtx->getAnalysis<RelaxedLiveVariables>()->isLive(Loc, VR->getDecl()))
394      return true;
395
396    if (!includeStoreBindings)
397      return false;
398
399    unsigned &cachedQuery =
400      const_cast<SymbolReaper*>(this)->includedRegionCache[VR];
401
402    if (cachedQuery) {
403      return cachedQuery == 1;
404    }
405
406    // Query the store to see if the region occurs in any live bindings.
407    if (Store store = reapedStore.getStore()) {
408      bool hasRegion =
409        reapedStore.getStoreManager().includedInBindings(store, VR);
410      cachedQuery = hasRegion ? 1 : 2;
411      return hasRegion;
412    }
413
414    return false;
415  }
416
417  return VarContext->isParentOf(CurrentContext);
418}
419
420SymbolVisitor::~SymbolVisitor() {}
421