clang  9.0.0svn
SimpleSValBuilder.cpp
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1 // SimpleSValBuilder.cpp - A basic SValBuilder -----------------------*- C++ -*-
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines SimpleSValBuilder, a basic implementation of SValBuilder.
10 //
11 //===----------------------------------------------------------------------===//
12 
19 
20 using namespace clang;
21 using namespace ento;
22 
23 namespace {
24 class SimpleSValBuilder : public SValBuilder {
25 protected:
26  SVal dispatchCast(SVal val, QualType castTy) override;
27  SVal evalCastFromNonLoc(NonLoc val, QualType castTy) override;
28  SVal evalCastFromLoc(Loc val, QualType castTy) override;
29 
30 public:
31  SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context,
32  ProgramStateManager &stateMgr)
33  : SValBuilder(alloc, context, stateMgr) {}
34  ~SimpleSValBuilder() override {}
35 
36  SVal evalMinus(NonLoc val) override;
37  SVal evalComplement(NonLoc val) override;
38  SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op,
39  NonLoc lhs, NonLoc rhs, QualType resultTy) override;
40  SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op,
41  Loc lhs, Loc rhs, QualType resultTy) override;
42  SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op,
43  Loc lhs, NonLoc rhs, QualType resultTy) override;
44 
45  /// getKnownValue - evaluates a given SVal. If the SVal has only one possible
46  /// (integer) value, that value is returned. Otherwise, returns NULL.
47  const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V) override;
48 
49  /// Recursively descends into symbolic expressions and replaces symbols
50  /// with their known values (in the sense of the getKnownValue() method).
51  SVal simplifySVal(ProgramStateRef State, SVal V) override;
52 
53  SVal MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op,
54  const llvm::APSInt &RHS, QualType resultTy);
55 };
56 } // end anonymous namespace
57 
58 SValBuilder *ento::createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc,
59  ASTContext &context,
60  ProgramStateManager &stateMgr) {
61  return new SimpleSValBuilder(alloc, context, stateMgr);
62 }
63 
64 //===----------------------------------------------------------------------===//
65 // Transfer function for Casts.
66 //===----------------------------------------------------------------------===//
67 
68 SVal SimpleSValBuilder::dispatchCast(SVal Val, QualType CastTy) {
69  assert(Val.getAs<Loc>() || Val.getAs<NonLoc>());
70  return Val.getAs<Loc>() ? evalCastFromLoc(Val.castAs<Loc>(), CastTy)
71  : evalCastFromNonLoc(Val.castAs<NonLoc>(), CastTy);
72 }
73 
74 SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) {
75  bool isLocType = Loc::isLocType(castTy);
76  if (val.getAs<nonloc::PointerToMember>())
77  return val;
78 
80  if (isLocType)
81  return LI->getLoc();
82  // FIXME: Correctly support promotions/truncations.
83  unsigned castSize = Context.getIntWidth(castTy);
84  if (castSize == LI->getNumBits())
85  return val;
86  return makeLocAsInteger(LI->getLoc(), castSize);
87  }
88 
89  if (const SymExpr *se = val.getAsSymbolicExpression()) {
90  QualType T = Context.getCanonicalType(se->getType());
91  // If types are the same or both are integers, ignore the cast.
92  // FIXME: Remove this hack when we support symbolic truncation/extension.
93  // HACK: If both castTy and T are integers, ignore the cast. This is
94  // not a permanent solution. Eventually we want to precisely handle
95  // extension/truncation of symbolic integers. This prevents us from losing
96  // precision when we assign 'x = y' and 'y' is symbolic and x and y are
97  // different integer types.
98  if (haveSameType(T, castTy))
99  return val;
100 
101  if (!isLocType)
102  return makeNonLoc(se, T, castTy);
103  return UnknownVal();
104  }
105 
106  // If value is a non-integer constant, produce unknown.
107  if (!val.getAs<nonloc::ConcreteInt>())
108  return UnknownVal();
109 
110  // Handle casts to a boolean type.
111  if (castTy->isBooleanType()) {
112  bool b = val.castAs<nonloc::ConcreteInt>().getValue().getBoolValue();
113  return makeTruthVal(b, castTy);
114  }
115 
116  // Only handle casts from integers to integers - if val is an integer constant
117  // being cast to a non-integer type, produce unknown.
118  if (!isLocType && !castTy->isIntegralOrEnumerationType())
119  return UnknownVal();
120 
121  llvm::APSInt i = val.castAs<nonloc::ConcreteInt>().getValue();
122  BasicVals.getAPSIntType(castTy).apply(i);
123 
124  if (isLocType)
125  return makeIntLocVal(i);
126  else
127  return makeIntVal(i);
128 }
129 
130 SVal SimpleSValBuilder::evalCastFromLoc(Loc val, QualType castTy) {
131 
132  // Casts from pointers -> pointers, just return the lval.
133  //
134  // Casts from pointers -> references, just return the lval. These
135  // can be introduced by the frontend for corner cases, e.g
136  // casting from va_list* to __builtin_va_list&.
137  //
138  if (Loc::isLocType(castTy) || castTy->isReferenceType())
139  return val;
140 
141  // FIXME: Handle transparent unions where a value can be "transparently"
142  // lifted into a union type.
143  if (castTy->isUnionType())
144  return UnknownVal();
145 
146  // Casting a Loc to a bool will almost always be true,
147  // unless this is a weak function or a symbolic region.
148  if (castTy->isBooleanType()) {
149  switch (val.getSubKind()) {
150  case loc::MemRegionValKind: {
151  const MemRegion *R = val.castAs<loc::MemRegionVal>().getRegion();
152  if (const FunctionCodeRegion *FTR = dyn_cast<FunctionCodeRegion>(R))
153  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(FTR->getDecl()))
154  if (FD->isWeak())
155  // FIXME: Currently we are using an extent symbol here,
156  // because there are no generic region address metadata
157  // symbols to use, only content metadata.
158  return nonloc::SymbolVal(SymMgr.getExtentSymbol(FTR));
159 
160  if (const SymbolicRegion *SymR = R->getSymbolicBase())
161  return makeNonLoc(SymR->getSymbol(), BO_NE,
162  BasicVals.getZeroWithPtrWidth(), castTy);
163 
164  // FALL-THROUGH
165  LLVM_FALLTHROUGH;
166  }
167 
168  case loc::GotoLabelKind:
169  // Labels and non-symbolic memory regions are always true.
170  return makeTruthVal(true, castTy);
171  }
172  }
173 
174  if (castTy->isIntegralOrEnumerationType()) {
175  unsigned BitWidth = Context.getIntWidth(castTy);
176 
177  if (!val.getAs<loc::ConcreteInt>())
178  return makeLocAsInteger(val, BitWidth);
179 
180  llvm::APSInt i = val.castAs<loc::ConcreteInt>().getValue();
181  BasicVals.getAPSIntType(castTy).apply(i);
182  return makeIntVal(i);
183  }
184 
185  // All other cases: return 'UnknownVal'. This includes casting pointers
186  // to floats, which is probably badness it itself, but this is a good
187  // intermediate solution until we do something better.
188  return UnknownVal();
189 }
190 
191 //===----------------------------------------------------------------------===//
192 // Transfer function for unary operators.
193 //===----------------------------------------------------------------------===//
194 
195 SVal SimpleSValBuilder::evalMinus(NonLoc val) {
196  switch (val.getSubKind()) {
197  case nonloc::ConcreteIntKind:
198  return val.castAs<nonloc::ConcreteInt>().evalMinus(*this);
199  default:
200  return UnknownVal();
201  }
202 }
203 
204 SVal SimpleSValBuilder::evalComplement(NonLoc X) {
205  switch (X.getSubKind()) {
206  case nonloc::ConcreteIntKind:
207  return X.castAs<nonloc::ConcreteInt>().evalComplement(*this);
208  default:
209  return UnknownVal();
210  }
211 }
212 
213 //===----------------------------------------------------------------------===//
214 // Transfer function for binary operators.
215 //===----------------------------------------------------------------------===//
216 
217 SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS,
219  const llvm::APSInt &RHS,
220  QualType resultTy) {
221  bool isIdempotent = false;
222 
223  // Check for a few special cases with known reductions first.
224  switch (op) {
225  default:
226  // We can't reduce this case; just treat it normally.
227  break;
228  case BO_Mul:
229  // a*0 and a*1
230  if (RHS == 0)
231  return makeIntVal(0, resultTy);
232  else if (RHS == 1)
233  isIdempotent = true;
234  break;
235  case BO_Div:
236  // a/0 and a/1
237  if (RHS == 0)
238  // This is also handled elsewhere.
239  return UndefinedVal();
240  else if (RHS == 1)
241  isIdempotent = true;
242  break;
243  case BO_Rem:
244  // a%0 and a%1
245  if (RHS == 0)
246  // This is also handled elsewhere.
247  return UndefinedVal();
248  else if (RHS == 1)
249  return makeIntVal(0, resultTy);
250  break;
251  case BO_Add:
252  case BO_Sub:
253  case BO_Shl:
254  case BO_Shr:
255  case BO_Xor:
256  // a+0, a-0, a<<0, a>>0, a^0
257  if (RHS == 0)
258  isIdempotent = true;
259  break;
260  case BO_And:
261  // a&0 and a&(~0)
262  if (RHS == 0)
263  return makeIntVal(0, resultTy);
264  else if (RHS.isAllOnesValue())
265  isIdempotent = true;
266  break;
267  case BO_Or:
268  // a|0 and a|(~0)
269  if (RHS == 0)
270  isIdempotent = true;
271  else if (RHS.isAllOnesValue()) {
272  const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS);
273  return nonloc::ConcreteInt(Result);
274  }
275  break;
276  }
277 
278  // Idempotent ops (like a*1) can still change the type of an expression.
279  // Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the
280  // dirty work.
281  if (isIdempotent)
282  return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy);
283 
284  // If we reach this point, the expression cannot be simplified.
285  // Make a SymbolVal for the entire expression, after converting the RHS.
286  const llvm::APSInt *ConvertedRHS = &RHS;
288  // We're looking for a type big enough to compare the symbolic value
289  // with the given constant.
290  // FIXME: This is an approximation of Sema::UsualArithmeticConversions.
291  ASTContext &Ctx = getContext();
292  QualType SymbolType = LHS->getType();
293  uint64_t ValWidth = RHS.getBitWidth();
294  uint64_t TypeWidth = Ctx.getTypeSize(SymbolType);
295 
296  if (ValWidth < TypeWidth) {
297  // If the value is too small, extend it.
298  ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
299  } else if (ValWidth == TypeWidth) {
300  // If the value is signed but the symbol is unsigned, do the comparison
301  // in unsigned space. [C99 6.3.1.8]
302  // (For the opposite case, the value is already unsigned.)
303  if (RHS.isSigned() && !SymbolType->isSignedIntegerOrEnumerationType())
304  ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
305  }
306  } else
307  ConvertedRHS = &BasicVals.Convert(resultTy, RHS);
308 
309  return makeNonLoc(LHS, op, *ConvertedRHS, resultTy);
310 }
311 
312 // See if Sym is known to be a relation Rel with Bound.
314  llvm::APSInt Bound, ProgramStateRef State) {
315  SValBuilder &SVB = State->getStateManager().getSValBuilder();
316  SVal Result =
317  SVB.evalBinOpNN(State, Rel, nonloc::SymbolVal(Sym),
318  nonloc::ConcreteInt(Bound), SVB.getConditionType());
319  if (auto DV = Result.getAs<DefinedSVal>()) {
320  return !State->assume(*DV, false);
321  }
322  return false;
323 }
324 
325 // See if Sym is known to be within [min/4, max/4], where min and max
326 // are the bounds of the symbol's integral type. With such symbols,
327 // some manipulations can be performed without the risk of overflow.
328 // assume() doesn't cause infinite recursion because we should be dealing
329 // with simpler symbols on every recursive call.
332  SValBuilder &SVB = State->getStateManager().getSValBuilder();
333  BasicValueFactory &BV = SVB.getBasicValueFactory();
334 
335  QualType T = Sym->getType();
336  assert(T->isSignedIntegerOrEnumerationType() &&
337  "This only works with signed integers!");
338  APSIntType AT = BV.getAPSIntType(T);
339 
340  llvm::APSInt Max = AT.getMaxValue() / AT.getValue(4), Min = -Max;
341  return isInRelation(BO_LE, Sym, Max, State) &&
342  isInRelation(BO_GE, Sym, Min, State);
343 }
344 
345 // Same for the concrete integers: see if I is within [min/4, max/4].
346 static bool isWithinConstantOverflowBounds(llvm::APSInt I) {
347  APSIntType AT(I);
348  assert(!AT.isUnsigned() &&
349  "This only works with signed integers!");
350 
351  llvm::APSInt Max = AT.getMaxValue() / AT.getValue(4), Min = -Max;
352  return (I <= Max) && (I >= -Max);
353 }
354 
355 static std::pair<SymbolRef, llvm::APSInt>
356 decomposeSymbol(SymbolRef Sym, BasicValueFactory &BV) {
357  if (const auto *SymInt = dyn_cast<SymIntExpr>(Sym))
358  if (BinaryOperator::isAdditiveOp(SymInt->getOpcode()))
359  return std::make_pair(SymInt->getLHS(),
360  (SymInt->getOpcode() == BO_Add) ?
361  (SymInt->getRHS()) :
362  (-SymInt->getRHS()));
363 
364  // Fail to decompose: "reduce" the problem to the "$x + 0" case.
365  return std::make_pair(Sym, BV.getValue(0, Sym->getType()));
366 }
367 
368 // Simplify "(LSym + LInt) Op (RSym + RInt)" assuming all values are of the
369 // same signed integral type and no overflows occur (which should be checked
370 // by the caller).
373  SymbolRef LSym, llvm::APSInt LInt,
374  SymbolRef RSym, llvm::APSInt RInt) {
375  SValBuilder &SVB = State->getStateManager().getSValBuilder();
376  BasicValueFactory &BV = SVB.getBasicValueFactory();
377  SymbolManager &SymMgr = SVB.getSymbolManager();
378 
379  QualType SymTy = LSym->getType();
380  assert(SymTy == RSym->getType() &&
381  "Symbols are not of the same type!");
382  assert(APSIntType(LInt) == BV.getAPSIntType(SymTy) &&
383  "Integers are not of the same type as symbols!");
384  assert(APSIntType(RInt) == BV.getAPSIntType(SymTy) &&
385  "Integers are not of the same type as symbols!");
386 
387  QualType ResultTy;
389  ResultTy = SVB.getConditionType();
390  else if (BinaryOperator::isAdditiveOp(Op))
391  ResultTy = SymTy;
392  else
393  llvm_unreachable("Operation not suitable for unchecked rearrangement!");
394 
395  // FIXME: Can we use assume() without getting into an infinite recursion?
396  if (LSym == RSym)
397  return SVB.evalBinOpNN(State, Op, nonloc::ConcreteInt(LInt),
398  nonloc::ConcreteInt(RInt), ResultTy)
399  .castAs<NonLoc>();
400 
401  SymbolRef ResultSym = nullptr;
402  BinaryOperator::Opcode ResultOp;
403  llvm::APSInt ResultInt;
405  // Prefer comparing to a non-negative number.
406  // FIXME: Maybe it'd be better to have consistency in
407  // "$x - $y" vs. "$y - $x" because those are solver's keys.
408  if (LInt > RInt) {
409  ResultSym = SymMgr.getSymSymExpr(RSym, BO_Sub, LSym, SymTy);
411  ResultInt = LInt - RInt; // Opposite order!
412  } else {
413  ResultSym = SymMgr.getSymSymExpr(LSym, BO_Sub, RSym, SymTy);
414  ResultOp = Op;
415  ResultInt = RInt - LInt; // Opposite order!
416  }
417  } else {
418  ResultSym = SymMgr.getSymSymExpr(LSym, Op, RSym, SymTy);
419  ResultInt = (Op == BO_Add) ? (LInt + RInt) : (LInt - RInt);
420  ResultOp = BO_Add;
421  // Bring back the cosmetic difference.
422  if (ResultInt < 0) {
423  ResultInt = -ResultInt;
424  ResultOp = BO_Sub;
425  } else if (ResultInt == 0) {
426  // Shortcut: Simplify "$x + 0" to "$x".
427  return nonloc::SymbolVal(ResultSym);
428  }
429  }
430  const llvm::APSInt &PersistentResultInt = BV.getValue(ResultInt);
431  return nonloc::SymbolVal(
432  SymMgr.getSymIntExpr(ResultSym, ResultOp, PersistentResultInt, ResultTy));
433 }
434 
435 // Rearrange if symbol type matches the result type and if the operator is a
436 // comparison operator, both symbol and constant must be within constant
437 // overflow bounds.
439  SymbolRef Sym, llvm::APSInt Int, QualType Ty) {
440  return Sym->getType() == Ty &&
442  (isWithinConstantOverflowBounds(Sym, State) &&
444 }
445 
446 static Optional<NonLoc> tryRearrange(ProgramStateRef State,
447  BinaryOperator::Opcode Op, NonLoc Lhs,
448  NonLoc Rhs, QualType ResultTy) {
449  ProgramStateManager &StateMgr = State->getStateManager();
450  SValBuilder &SVB = StateMgr.getSValBuilder();
451 
452  // We expect everything to be of the same type - this type.
453  QualType SingleTy;
454 
455  auto &Opts =
456  StateMgr.getOwningEngine().getAnalysisManager().getAnalyzerOptions();
457 
458  // FIXME: After putting complexity threshold to the symbols we can always
459  // rearrange additive operations but rearrange comparisons only if
460  // option is set.
461  if(!Opts.ShouldAggressivelySimplifyBinaryOperation)
462  return None;
463 
464  SymbolRef LSym = Lhs.getAsSymbol();
465  if (!LSym)
466  return None;
467 
469  SingleTy = LSym->getType();
470  if (ResultTy != SVB.getConditionType())
471  return None;
472  // Initialize SingleTy later with a symbol's type.
473  } else if (BinaryOperator::isAdditiveOp(Op)) {
474  SingleTy = ResultTy;
475  if (LSym->getType() != SingleTy)
476  return None;
477  } else {
478  // Don't rearrange other operations.
479  return None;
480  }
481 
482  assert(!SingleTy.isNull() && "We should have figured out the type by now!");
483 
484  // Rearrange signed symbolic expressions only
485  if (!SingleTy->isSignedIntegerOrEnumerationType())
486  return None;
487 
488  SymbolRef RSym = Rhs.getAsSymbol();
489  if (!RSym || RSym->getType() != SingleTy)
490  return None;
491 
492  BasicValueFactory &BV = State->getBasicVals();
493  llvm::APSInt LInt, RInt;
494  std::tie(LSym, LInt) = decomposeSymbol(LSym, BV);
495  std::tie(RSym, RInt) = decomposeSymbol(RSym, BV);
496  if (!shouldRearrange(State, Op, LSym, LInt, SingleTy) ||
497  !shouldRearrange(State, Op, RSym, RInt, SingleTy))
498  return None;
499 
500  // We know that no overflows can occur anymore.
501  return doRearrangeUnchecked(State, Op, LSym, LInt, RSym, RInt);
502 }
503 
504 SVal SimpleSValBuilder::evalBinOpNN(ProgramStateRef state,
506  NonLoc lhs, NonLoc rhs,
507  QualType resultTy) {
508  NonLoc InputLHS = lhs;
509  NonLoc InputRHS = rhs;
510 
511  // Handle trivial case where left-side and right-side are the same.
512  if (lhs == rhs)
513  switch (op) {
514  default:
515  break;
516  case BO_EQ:
517  case BO_LE:
518  case BO_GE:
519  return makeTruthVal(true, resultTy);
520  case BO_LT:
521  case BO_GT:
522  case BO_NE:
523  return makeTruthVal(false, resultTy);
524  case BO_Xor:
525  case BO_Sub:
526  if (resultTy->isIntegralOrEnumerationType())
527  return makeIntVal(0, resultTy);
528  return evalCastFromNonLoc(makeIntVal(0, /*Unsigned=*/false), resultTy);
529  case BO_Or:
530  case BO_And:
531  return evalCastFromNonLoc(lhs, resultTy);
532  }
533 
534  while (1) {
535  switch (lhs.getSubKind()) {
536  default:
537  return makeSymExprValNN(op, lhs, rhs, resultTy);
538  case nonloc::PointerToMemberKind: {
539  assert(rhs.getSubKind() == nonloc::PointerToMemberKind &&
540  "Both SVals should have pointer-to-member-type");
541  auto LPTM = lhs.castAs<nonloc::PointerToMember>(),
542  RPTM = rhs.castAs<nonloc::PointerToMember>();
543  auto LPTMD = LPTM.getPTMData(), RPTMD = RPTM.getPTMData();
544  switch (op) {
545  case BO_EQ:
546  return makeTruthVal(LPTMD == RPTMD, resultTy);
547  case BO_NE:
548  return makeTruthVal(LPTMD != RPTMD, resultTy);
549  default:
550  return UnknownVal();
551  }
552  }
553  case nonloc::LocAsIntegerKind: {
554  Loc lhsL = lhs.castAs<nonloc::LocAsInteger>().getLoc();
555  switch (rhs.getSubKind()) {
556  case nonloc::LocAsIntegerKind:
557  // FIXME: at the moment the implementation
558  // of modeling "pointers as integers" is not complete.
560  return UnknownVal();
561  return evalBinOpLL(state, op, lhsL,
562  rhs.castAs<nonloc::LocAsInteger>().getLoc(),
563  resultTy);
564  case nonloc::ConcreteIntKind: {
565  // FIXME: at the moment the implementation
566  // of modeling "pointers as integers" is not complete.
568  return UnknownVal();
569  // Transform the integer into a location and compare.
570  // FIXME: This only makes sense for comparisons. If we want to, say,
571  // add 1 to a LocAsInteger, we'd better unpack the Loc and add to it,
572  // then pack it back into a LocAsInteger.
573  llvm::APSInt i = rhs.castAs<nonloc::ConcreteInt>().getValue();
574  // If the region has a symbolic base, pay attention to the type; it
575  // might be coming from a non-default address space. For non-symbolic
576  // regions it doesn't matter that much because such comparisons would
577  // most likely evaluate to concrete false anyway. FIXME: We might
578  // still need to handle the non-comparison case.
579  if (SymbolRef lSym = lhs.getAsLocSymbol(true))
580  BasicVals.getAPSIntType(lSym->getType()).apply(i);
581  else
582  BasicVals.getAPSIntType(Context.VoidPtrTy).apply(i);
583  return evalBinOpLL(state, op, lhsL, makeLoc(i), resultTy);
584  }
585  default:
586  switch (op) {
587  case BO_EQ:
588  return makeTruthVal(false, resultTy);
589  case BO_NE:
590  return makeTruthVal(true, resultTy);
591  default:
592  // This case also handles pointer arithmetic.
593  return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
594  }
595  }
596  }
597  case nonloc::ConcreteIntKind: {
598  llvm::APSInt LHSValue = lhs.castAs<nonloc::ConcreteInt>().getValue();
599 
600  // If we're dealing with two known constants, just perform the operation.
601  if (const llvm::APSInt *KnownRHSValue = getKnownValue(state, rhs)) {
602  llvm::APSInt RHSValue = *KnownRHSValue;
604  // We're looking for a type big enough to compare the two values.
605  // FIXME: This is not correct. char + short will result in a promotion
606  // to int. Unfortunately we have lost types by this point.
607  APSIntType CompareType = std::max(APSIntType(LHSValue),
608  APSIntType(RHSValue));
609  CompareType.apply(LHSValue);
610  CompareType.apply(RHSValue);
611  } else if (!BinaryOperator::isShiftOp(op)) {
612  APSIntType IntType = BasicVals.getAPSIntType(resultTy);
613  IntType.apply(LHSValue);
614  IntType.apply(RHSValue);
615  }
616 
617  const llvm::APSInt *Result =
618  BasicVals.evalAPSInt(op, LHSValue, RHSValue);
619  if (!Result)
620  return UndefinedVal();
621 
622  return nonloc::ConcreteInt(*Result);
623  }
624 
625  // Swap the left and right sides and flip the operator if doing so
626  // allows us to better reason about the expression (this is a form
627  // of expression canonicalization).
628  // While we're at it, catch some special cases for non-commutative ops.
629  switch (op) {
630  case BO_LT:
631  case BO_GT:
632  case BO_LE:
633  case BO_GE:
635  LLVM_FALLTHROUGH;
636  case BO_EQ:
637  case BO_NE:
638  case BO_Add:
639  case BO_Mul:
640  case BO_And:
641  case BO_Xor:
642  case BO_Or:
643  std::swap(lhs, rhs);
644  continue;
645  case BO_Shr:
646  // (~0)>>a
647  if (LHSValue.isAllOnesValue() && LHSValue.isSigned())
648  return evalCastFromNonLoc(lhs, resultTy);
649  LLVM_FALLTHROUGH;
650  case BO_Shl:
651  // 0<<a and 0>>a
652  if (LHSValue == 0)
653  return evalCastFromNonLoc(lhs, resultTy);
654  return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
655  default:
656  return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
657  }
658  }
659  case nonloc::SymbolValKind: {
660  // We only handle LHS as simple symbols or SymIntExprs.
661  SymbolRef Sym = lhs.castAs<nonloc::SymbolVal>().getSymbol();
662 
663  // LHS is a symbolic expression.
664  if (const SymIntExpr *symIntExpr = dyn_cast<SymIntExpr>(Sym)) {
665 
666  // Is this a logical not? (!x is represented as x == 0.)
667  if (op == BO_EQ && rhs.isZeroConstant()) {
668  // We know how to negate certain expressions. Simplify them here.
669 
670  BinaryOperator::Opcode opc = symIntExpr->getOpcode();
671  switch (opc) {
672  default:
673  // We don't know how to negate this operation.
674  // Just handle it as if it were a normal comparison to 0.
675  break;
676  case BO_LAnd:
677  case BO_LOr:
678  llvm_unreachable("Logical operators handled by branching logic.");
679  case BO_Assign:
680  case BO_MulAssign:
681  case BO_DivAssign:
682  case BO_RemAssign:
683  case BO_AddAssign:
684  case BO_SubAssign:
685  case BO_ShlAssign:
686  case BO_ShrAssign:
687  case BO_AndAssign:
688  case BO_XorAssign:
689  case BO_OrAssign:
690  case BO_Comma:
691  llvm_unreachable("'=' and ',' operators handled by ExprEngine.");
692  case BO_PtrMemD:
693  case BO_PtrMemI:
694  llvm_unreachable("Pointer arithmetic not handled here.");
695  case BO_LT:
696  case BO_GT:
697  case BO_LE:
698  case BO_GE:
699  case BO_EQ:
700  case BO_NE:
701  assert(resultTy->isBooleanType() ||
702  resultTy == getConditionType());
703  assert(symIntExpr->getType()->isBooleanType() ||
704  getContext().hasSameUnqualifiedType(symIntExpr->getType(),
705  getConditionType()));
706  // Negate the comparison and make a value.
708  return makeNonLoc(symIntExpr->getLHS(), opc,
709  symIntExpr->getRHS(), resultTy);
710  }
711  }
712 
713  // For now, only handle expressions whose RHS is a constant.
714  if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs)) {
715  // If both the LHS and the current expression are additive,
716  // fold their constants and try again.
718  BinaryOperator::Opcode lop = symIntExpr->getOpcode();
719  if (BinaryOperator::isAdditiveOp(lop)) {
720  // Convert the two constants to a common type, then combine them.
721 
722  // resultTy may not be the best type to convert to, but it's
723  // probably the best choice in expressions with mixed type
724  // (such as x+1U+2LL). The rules for implicit conversions should
725  // choose a reasonable type to preserve the expression, and will
726  // at least match how the value is going to be used.
727  APSIntType IntType = BasicVals.getAPSIntType(resultTy);
728  const llvm::APSInt &first = IntType.convert(symIntExpr->getRHS());
729  const llvm::APSInt &second = IntType.convert(*RHSValue);
730 
731  const llvm::APSInt *newRHS;
732  if (lop == op)
733  newRHS = BasicVals.evalAPSInt(BO_Add, first, second);
734  else
735  newRHS = BasicVals.evalAPSInt(BO_Sub, first, second);
736 
737  assert(newRHS && "Invalid operation despite common type!");
738  rhs = nonloc::ConcreteInt(*newRHS);
739  lhs = nonloc::SymbolVal(symIntExpr->getLHS());
740  op = lop;
741  continue;
742  }
743  }
744 
745  // Otherwise, make a SymIntExpr out of the expression.
746  return MakeSymIntVal(symIntExpr, op, *RHSValue, resultTy);
747  }
748  }
749 
750  // Does the symbolic expression simplify to a constant?
751  // If so, "fold" the constant by setting 'lhs' to a ConcreteInt
752  // and try again.
753  SVal simplifiedLhs = simplifySVal(state, lhs);
754  if (simplifiedLhs != lhs)
755  if (auto simplifiedLhsAsNonLoc = simplifiedLhs.getAs<NonLoc>()) {
756  lhs = *simplifiedLhsAsNonLoc;
757  continue;
758  }
759 
760  // Is the RHS a constant?
761  if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs))
762  return MakeSymIntVal(Sym, op, *RHSValue, resultTy);
763 
764  if (Optional<NonLoc> V = tryRearrange(state, op, lhs, rhs, resultTy))
765  return *V;
766 
767  // Give up -- this is not a symbolic expression we can handle.
768  return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
769  }
770  }
771  }
772 }
773 
774 static SVal evalBinOpFieldRegionFieldRegion(const FieldRegion *LeftFR,
775  const FieldRegion *RightFR,
777  QualType resultTy,
778  SimpleSValBuilder &SVB) {
779  // Only comparisons are meaningful here!
781  return UnknownVal();
782 
783  // Next, see if the two FRs have the same super-region.
784  // FIXME: This doesn't handle casts yet, and simply stripping the casts
785  // doesn't help.
786  if (LeftFR->getSuperRegion() != RightFR->getSuperRegion())
787  return UnknownVal();
788 
789  const FieldDecl *LeftFD = LeftFR->getDecl();
790  const FieldDecl *RightFD = RightFR->getDecl();
791  const RecordDecl *RD = LeftFD->getParent();
792 
793  // Make sure the two FRs are from the same kind of record. Just in case!
794  // FIXME: This is probably where inheritance would be a problem.
795  if (RD != RightFD->getParent())
796  return UnknownVal();
797 
798  // We know for sure that the two fields are not the same, since that
799  // would have given us the same SVal.
800  if (op == BO_EQ)
801  return SVB.makeTruthVal(false, resultTy);
802  if (op == BO_NE)
803  return SVB.makeTruthVal(true, resultTy);
804 
805  // Iterate through the fields and see which one comes first.
806  // [C99 6.7.2.1.13] "Within a structure object, the non-bit-field
807  // members and the units in which bit-fields reside have addresses that
808  // increase in the order in which they are declared."
809  bool leftFirst = (op == BO_LT || op == BO_LE);
810  for (const auto *I : RD->fields()) {
811  if (I == LeftFD)
812  return SVB.makeTruthVal(leftFirst, resultTy);
813  if (I == RightFD)
814  return SVB.makeTruthVal(!leftFirst, resultTy);
815  }
816 
817  llvm_unreachable("Fields not found in parent record's definition");
818 }
819 
820 // FIXME: all this logic will change if/when we have MemRegion::getLocation().
821 SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state,
823  Loc lhs, Loc rhs,
824  QualType resultTy) {
825  // Only comparisons and subtractions are valid operations on two pointers.
826  // See [C99 6.5.5 through 6.5.14] or [C++0x 5.6 through 5.15].
827  // However, if a pointer is casted to an integer, evalBinOpNN may end up
828  // calling this function with another operation (PR7527). We don't attempt to
829  // model this for now, but it could be useful, particularly when the
830  // "location" is actually an integer value that's been passed through a void*.
831  if (!(BinaryOperator::isComparisonOp(op) || op == BO_Sub))
832  return UnknownVal();
833 
834  // Special cases for when both sides are identical.
835  if (lhs == rhs) {
836  switch (op) {
837  default:
838  llvm_unreachable("Unimplemented operation for two identical values");
839  case BO_Sub:
840  return makeZeroVal(resultTy);
841  case BO_EQ:
842  case BO_LE:
843  case BO_GE:
844  return makeTruthVal(true, resultTy);
845  case BO_NE:
846  case BO_LT:
847  case BO_GT:
848  return makeTruthVal(false, resultTy);
849  }
850  }
851 
852  switch (lhs.getSubKind()) {
853  default:
854  llvm_unreachable("Ordering not implemented for this Loc.");
855 
856  case loc::GotoLabelKind:
857  // The only thing we know about labels is that they're non-null.
858  if (rhs.isZeroConstant()) {
859  switch (op) {
860  default:
861  break;
862  case BO_Sub:
863  return evalCastFromLoc(lhs, resultTy);
864  case BO_EQ:
865  case BO_LE:
866  case BO_LT:
867  return makeTruthVal(false, resultTy);
868  case BO_NE:
869  case BO_GT:
870  case BO_GE:
871  return makeTruthVal(true, resultTy);
872  }
873  }
874  // There may be two labels for the same location, and a function region may
875  // have the same address as a label at the start of the function (depending
876  // on the ABI).
877  // FIXME: we can probably do a comparison against other MemRegions, though.
878  // FIXME: is there a way to tell if two labels refer to the same location?
879  return UnknownVal();
880 
881  case loc::ConcreteIntKind: {
882  // If one of the operands is a symbol and the other is a constant,
883  // build an expression for use by the constraint manager.
884  if (SymbolRef rSym = rhs.getAsLocSymbol()) {
885  // We can only build expressions with symbols on the left,
886  // so we need a reversible operator.
887  if (!BinaryOperator::isComparisonOp(op) || op == BO_Cmp)
888  return UnknownVal();
889 
890  const llvm::APSInt &lVal = lhs.castAs<loc::ConcreteInt>().getValue();
892  return makeNonLoc(rSym, op, lVal, resultTy);
893  }
894 
895  // If both operands are constants, just perform the operation.
896  if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
897  SVal ResultVal =
898  lhs.castAs<loc::ConcreteInt>().evalBinOp(BasicVals, op, *rInt);
899  if (Optional<NonLoc> Result = ResultVal.getAs<NonLoc>())
900  return evalCastFromNonLoc(*Result, resultTy);
901 
902  assert(!ResultVal.getAs<Loc>() && "Loc-Loc ops should not produce Locs");
903  return UnknownVal();
904  }
905 
906  // Special case comparisons against NULL.
907  // This must come after the test if the RHS is a symbol, which is used to
908  // build constraints. The address of any non-symbolic region is guaranteed
909  // to be non-NULL, as is any label.
910  assert(rhs.getAs<loc::MemRegionVal>() || rhs.getAs<loc::GotoLabel>());
911  if (lhs.isZeroConstant()) {
912  switch (op) {
913  default:
914  break;
915  case BO_EQ:
916  case BO_GT:
917  case BO_GE:
918  return makeTruthVal(false, resultTy);
919  case BO_NE:
920  case BO_LT:
921  case BO_LE:
922  return makeTruthVal(true, resultTy);
923  }
924  }
925 
926  // Comparing an arbitrary integer to a region or label address is
927  // completely unknowable.
928  return UnknownVal();
929  }
930  case loc::MemRegionValKind: {
931  if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
932  // If one of the operands is a symbol and the other is a constant,
933  // build an expression for use by the constraint manager.
934  if (SymbolRef lSym = lhs.getAsLocSymbol(true)) {
936  return MakeSymIntVal(lSym, op, rInt->getValue(), resultTy);
937  return UnknownVal();
938  }
939  // Special case comparisons to NULL.
940  // This must come after the test if the LHS is a symbol, which is used to
941  // build constraints. The address of any non-symbolic region is guaranteed
942  // to be non-NULL.
943  if (rInt->isZeroConstant()) {
944  if (op == BO_Sub)
945  return evalCastFromLoc(lhs, resultTy);
946 
948  QualType boolType = getContext().BoolTy;
949  NonLoc l = evalCastFromLoc(lhs, boolType).castAs<NonLoc>();
950  NonLoc r = makeTruthVal(false, boolType).castAs<NonLoc>();
951  return evalBinOpNN(state, op, l, r, resultTy);
952  }
953  }
954 
955  // Comparing a region to an arbitrary integer is completely unknowable.
956  return UnknownVal();
957  }
958 
959  // Get both values as regions, if possible.
960  const MemRegion *LeftMR = lhs.getAsRegion();
961  assert(LeftMR && "MemRegionValKind SVal doesn't have a region!");
962 
963  const MemRegion *RightMR = rhs.getAsRegion();
964  if (!RightMR)
965  // The RHS is probably a label, which in theory could address a region.
966  // FIXME: we can probably make a more useful statement about non-code
967  // regions, though.
968  return UnknownVal();
969 
970  const MemRegion *LeftBase = LeftMR->getBaseRegion();
971  const MemRegion *RightBase = RightMR->getBaseRegion();
972  const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace();
973  const MemSpaceRegion *RightMS = RightBase->getMemorySpace();
974  const MemSpaceRegion *UnknownMS = MemMgr.getUnknownRegion();
975 
976  // If the two regions are from different known memory spaces they cannot be
977  // equal. Also, assume that no symbolic region (whose memory space is
978  // unknown) is on the stack.
979  if (LeftMS != RightMS &&
980  ((LeftMS != UnknownMS && RightMS != UnknownMS) ||
981  (isa<StackSpaceRegion>(LeftMS) || isa<StackSpaceRegion>(RightMS)))) {
982  switch (op) {
983  default:
984  return UnknownVal();
985  case BO_EQ:
986  return makeTruthVal(false, resultTy);
987  case BO_NE:
988  return makeTruthVal(true, resultTy);
989  }
990  }
991 
992  // If both values wrap regions, see if they're from different base regions.
993  // Note, heap base symbolic regions are assumed to not alias with
994  // each other; for example, we assume that malloc returns different address
995  // on each invocation.
996  // FIXME: ObjC object pointers always reside on the heap, but currently
997  // we treat their memory space as unknown, because symbolic pointers
998  // to ObjC objects may alias. There should be a way to construct
999  // possibly-aliasing heap-based regions. For instance, MacOSXApiChecker
1000  // guesses memory space for ObjC object pointers manually instead of
1001  // relying on us.
1002  if (LeftBase != RightBase &&
1003  ((!isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) ||
1004  (isa<HeapSpaceRegion>(LeftMS) || isa<HeapSpaceRegion>(RightMS))) ){
1005  switch (op) {
1006  default:
1007  return UnknownVal();
1008  case BO_EQ:
1009  return makeTruthVal(false, resultTy);
1010  case BO_NE:
1011  return makeTruthVal(true, resultTy);
1012  }
1013  }
1014 
1015  // Handle special cases for when both regions are element regions.
1016  const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR);
1017  const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR);
1018  if (RightER && LeftER) {
1019  // Next, see if the two ERs have the same super-region and matching types.
1020  // FIXME: This should do something useful even if the types don't match,
1021  // though if both indexes are constant the RegionRawOffset path will
1022  // give the correct answer.
1023  if (LeftER->getSuperRegion() == RightER->getSuperRegion() &&
1024  LeftER->getElementType() == RightER->getElementType()) {
1025  // Get the left index and cast it to the correct type.
1026  // If the index is unknown or undefined, bail out here.
1027  SVal LeftIndexVal = LeftER->getIndex();
1028  Optional<NonLoc> LeftIndex = LeftIndexVal.getAs<NonLoc>();
1029  if (!LeftIndex)
1030  return UnknownVal();
1031  LeftIndexVal = evalCastFromNonLoc(*LeftIndex, ArrayIndexTy);
1032  LeftIndex = LeftIndexVal.getAs<NonLoc>();
1033  if (!LeftIndex)
1034  return UnknownVal();
1035 
1036  // Do the same for the right index.
1037  SVal RightIndexVal = RightER->getIndex();
1038  Optional<NonLoc> RightIndex = RightIndexVal.getAs<NonLoc>();
1039  if (!RightIndex)
1040  return UnknownVal();
1041  RightIndexVal = evalCastFromNonLoc(*RightIndex, ArrayIndexTy);
1042  RightIndex = RightIndexVal.getAs<NonLoc>();
1043  if (!RightIndex)
1044  return UnknownVal();
1045 
1046  // Actually perform the operation.
1047  // evalBinOpNN expects the two indexes to already be the right type.
1048  return evalBinOpNN(state, op, *LeftIndex, *RightIndex, resultTy);
1049  }
1050  }
1051 
1052  // Special handling of the FieldRegions, even with symbolic offsets.
1053  const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR);
1054  const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR);
1055  if (RightFR && LeftFR) {
1056  SVal R = evalBinOpFieldRegionFieldRegion(LeftFR, RightFR, op, resultTy,
1057  *this);
1058  if (!R.isUnknown())
1059  return R;
1060  }
1061 
1062  // Compare the regions using the raw offsets.
1063  RegionOffset LeftOffset = LeftMR->getAsOffset();
1064  RegionOffset RightOffset = RightMR->getAsOffset();
1065 
1066  if (LeftOffset.getRegion() != nullptr &&
1067  LeftOffset.getRegion() == RightOffset.getRegion() &&
1068  !LeftOffset.hasSymbolicOffset() && !RightOffset.hasSymbolicOffset()) {
1069  int64_t left = LeftOffset.getOffset();
1070  int64_t right = RightOffset.getOffset();
1071 
1072  switch (op) {
1073  default:
1074  return UnknownVal();
1075  case BO_LT:
1076  return makeTruthVal(left < right, resultTy);
1077  case BO_GT:
1078  return makeTruthVal(left > right, resultTy);
1079  case BO_LE:
1080  return makeTruthVal(left <= right, resultTy);
1081  case BO_GE:
1082  return makeTruthVal(left >= right, resultTy);
1083  case BO_EQ:
1084  return makeTruthVal(left == right, resultTy);
1085  case BO_NE:
1086  return makeTruthVal(left != right, resultTy);
1087  }
1088  }
1089 
1090  // At this point we're not going to get a good answer, but we can try
1091  // conjuring an expression instead.
1092  SymbolRef LHSSym = lhs.getAsLocSymbol();
1093  SymbolRef RHSSym = rhs.getAsLocSymbol();
1094  if (LHSSym && RHSSym)
1095  return makeNonLoc(LHSSym, op, RHSSym, resultTy);
1096 
1097  // If we get here, we have no way of comparing the regions.
1098  return UnknownVal();
1099  }
1100  }
1101 }
1102 
1103 SVal SimpleSValBuilder::evalBinOpLN(ProgramStateRef state,
1105  Loc lhs, NonLoc rhs, QualType resultTy) {
1106  if (op >= BO_PtrMemD && op <= BO_PtrMemI) {
1107  if (auto PTMSV = rhs.getAs<nonloc::PointerToMember>()) {
1108  if (PTMSV->isNullMemberPointer())
1109  return UndefinedVal();
1110  if (const FieldDecl *FD = PTMSV->getDeclAs<FieldDecl>()) {
1111  SVal Result = lhs;
1112 
1113  for (const auto &I : *PTMSV)
1114  Result = StateMgr.getStoreManager().evalDerivedToBase(
1115  Result, I->getType(),I->isVirtual());
1116  return state->getLValue(FD, Result);
1117  }
1118  }
1119 
1120  return rhs;
1121  }
1122 
1123  assert(!BinaryOperator::isComparisonOp(op) &&
1124  "arguments to comparison ops must be of the same type");
1125 
1126  // Special case: rhs is a zero constant.
1127  if (rhs.isZeroConstant())
1128  return lhs;
1129 
1130  // Perserve the null pointer so that it can be found by the DerefChecker.
1131  if (lhs.isZeroConstant())
1132  return lhs;
1133 
1134  // We are dealing with pointer arithmetic.
1135 
1136  // Handle pointer arithmetic on constant values.
1137  if (Optional<nonloc::ConcreteInt> rhsInt = rhs.getAs<nonloc::ConcreteInt>()) {
1138  if (Optional<loc::ConcreteInt> lhsInt = lhs.getAs<loc::ConcreteInt>()) {
1139  const llvm::APSInt &leftI = lhsInt->getValue();
1140  assert(leftI.isUnsigned());
1141  llvm::APSInt rightI(rhsInt->getValue(), /* isUnsigned */ true);
1142 
1143  // Convert the bitwidth of rightI. This should deal with overflow
1144  // since we are dealing with concrete values.
1145  rightI = rightI.extOrTrunc(leftI.getBitWidth());
1146 
1147  // Offset the increment by the pointer size.
1148  llvm::APSInt Multiplicand(rightI.getBitWidth(), /* isUnsigned */ true);
1149  QualType pointeeType = resultTy->getPointeeType();
1150  Multiplicand = getContext().getTypeSizeInChars(pointeeType).getQuantity();
1151  rightI *= Multiplicand;
1152 
1153  // Compute the adjusted pointer.
1154  switch (op) {
1155  case BO_Add:
1156  rightI = leftI + rightI;
1157  break;
1158  case BO_Sub:
1159  rightI = leftI - rightI;
1160  break;
1161  default:
1162  llvm_unreachable("Invalid pointer arithmetic operation");
1163  }
1164  return loc::ConcreteInt(getBasicValueFactory().getValue(rightI));
1165  }
1166  }
1167 
1168  // Handle cases where 'lhs' is a region.
1169  if (const MemRegion *region = lhs.getAsRegion()) {
1170  rhs = convertToArrayIndex(rhs).castAs<NonLoc>();
1171  SVal index = UnknownVal();
1172  const SubRegion *superR = nullptr;
1173  // We need to know the type of the pointer in order to add an integer to it.
1174  // Depending on the type, different amount of bytes is added.
1175  QualType elementType;
1176 
1177  if (const ElementRegion *elemReg = dyn_cast<ElementRegion>(region)) {
1178  assert(op == BO_Add || op == BO_Sub);
1179  index = evalBinOpNN(state, op, elemReg->getIndex(), rhs,
1180  getArrayIndexType());
1181  superR = cast<SubRegion>(elemReg->getSuperRegion());
1182  elementType = elemReg->getElementType();
1183  }
1184  else if (isa<SubRegion>(region)) {
1185  assert(op == BO_Add || op == BO_Sub);
1186  index = (op == BO_Add) ? rhs : evalMinus(rhs);
1187  superR = cast<SubRegion>(region);
1188  // TODO: Is this actually reliable? Maybe improving our MemRegion
1189  // hierarchy to provide typed regions for all non-void pointers would be
1190  // better. For instance, we cannot extend this towards LocAsInteger
1191  // operations, where result type of the expression is integer.
1192  if (resultTy->isAnyPointerType())
1193  elementType = resultTy->getPointeeType();
1194  }
1195 
1196  // Represent arithmetic on void pointers as arithmetic on char pointers.
1197  // It is fine when a TypedValueRegion of char value type represents
1198  // a void pointer. Note that arithmetic on void pointers is a GCC extension.
1199  if (elementType->isVoidType())
1200  elementType = getContext().CharTy;
1201 
1202  if (Optional<NonLoc> indexV = index.getAs<NonLoc>()) {
1203  return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV,
1204  superR, getContext()));
1205  }
1206  }
1207  return UnknownVal();
1208 }
1209 
1210 const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state,
1211  SVal V) {
1212  V = simplifySVal(state, V);
1213  if (V.isUnknownOrUndef())
1214  return nullptr;
1215 
1216  if (Optional<loc::ConcreteInt> X = V.getAs<loc::ConcreteInt>())
1217  return &X->getValue();
1218 
1219  if (Optional<nonloc::ConcreteInt> X = V.getAs<nonloc::ConcreteInt>())
1220  return &X->getValue();
1221 
1222  if (SymbolRef Sym = V.getAsSymbol())
1223  return state->getConstraintManager().getSymVal(state, Sym);
1224 
1225  // FIXME: Add support for SymExprs.
1226  return nullptr;
1227 }
1228 
1229 SVal SimpleSValBuilder::simplifySVal(ProgramStateRef State, SVal V) {
1230  // For now, this function tries to constant-fold symbols inside a
1231  // nonloc::SymbolVal, and does nothing else. More simplifications should
1232  // be possible, such as constant-folding an index in an ElementRegion.
1233 
1234  class Simplifier : public FullSValVisitor<Simplifier, SVal> {
1236  SValBuilder &SVB;
1237 
1238  // Cache results for the lifetime of the Simplifier. Results change every
1239  // time new constraints are added to the program state, which is the whole
1240  // point of simplifying, and for that very reason it's pointless to maintain
1241  // the same cache for the duration of the whole analysis.
1242  llvm::DenseMap<SymbolRef, SVal> Cached;
1243 
1244  static bool isUnchanged(SymbolRef Sym, SVal Val) {
1245  return Sym == Val.getAsSymbol();
1246  }
1247 
1248  SVal cache(SymbolRef Sym, SVal V) {
1249  Cached[Sym] = V;
1250  return V;
1251  }
1252 
1253  SVal skip(SymbolRef Sym) {
1254  return cache(Sym, SVB.makeSymbolVal(Sym));
1255  }
1256 
1257  public:
1258  Simplifier(ProgramStateRef State)
1259  : State(State), SVB(State->getStateManager().getSValBuilder()) {}
1260 
1261  SVal VisitSymbolData(const SymbolData *S) {
1262  // No cache here.
1263  if (const llvm::APSInt *I =
1264  SVB.getKnownValue(State, SVB.makeSymbolVal(S)))
1265  return Loc::isLocType(S->getType()) ? (SVal)SVB.makeIntLocVal(*I)
1266  : (SVal)SVB.makeIntVal(*I);
1267  return SVB.makeSymbolVal(S);
1268  }
1269 
1270  // TODO: Support SymbolCast. Support IntSymExpr when/if we actually
1271  // start producing them.
1272 
1273  SVal VisitSymIntExpr(const SymIntExpr *S) {
1274  auto I = Cached.find(S);
1275  if (I != Cached.end())
1276  return I->second;
1277 
1278  SVal LHS = Visit(S->getLHS());
1279  if (isUnchanged(S->getLHS(), LHS))
1280  return skip(S);
1281 
1282  SVal RHS;
1283  // By looking at the APSInt in the right-hand side of S, we cannot
1284  // figure out if it should be treated as a Loc or as a NonLoc.
1285  // So make our guess by recalling that we cannot multiply pointers
1286  // or compare a pointer to an integer.
1287  if (Loc::isLocType(S->getLHS()->getType()) &&
1288  BinaryOperator::isComparisonOp(S->getOpcode())) {
1289  // The usual conversion of $sym to &SymRegion{$sym}, as they have
1290  // the same meaning for Loc-type symbols, but the latter form
1291  // is preferred in SVal computations for being Loc itself.
1292  if (SymbolRef Sym = LHS.getAsSymbol()) {
1293  assert(Loc::isLocType(Sym->getType()));
1294  LHS = SVB.makeLoc(Sym);
1295  }
1296  RHS = SVB.makeIntLocVal(S->getRHS());
1297  } else {
1298  RHS = SVB.makeIntVal(S->getRHS());
1299  }
1300 
1301  return cache(
1302  S, SVB.evalBinOp(State, S->getOpcode(), LHS, RHS, S->getType()));
1303  }
1304 
1305  SVal VisitSymSymExpr(const SymSymExpr *S) {
1306  auto I = Cached.find(S);
1307  if (I != Cached.end())
1308  return I->second;
1309 
1310  // For now don't try to simplify mixed Loc/NonLoc expressions
1311  // because they often appear from LocAsInteger operations
1312  // and we don't know how to combine a LocAsInteger
1313  // with a concrete value.
1314  if (Loc::isLocType(S->getLHS()->getType()) !=
1315  Loc::isLocType(S->getRHS()->getType()))
1316  return skip(S);
1317 
1318  SVal LHS = Visit(S->getLHS());
1319  SVal RHS = Visit(S->getRHS());
1320  if (isUnchanged(S->getLHS(), LHS) && isUnchanged(S->getRHS(), RHS))
1321  return skip(S);
1322 
1323  return cache(
1324  S, SVB.evalBinOp(State, S->getOpcode(), LHS, RHS, S->getType()));
1325  }
1326 
1327  SVal VisitSymExpr(SymbolRef S) { return nonloc::SymbolVal(S); }
1328 
1329  SVal VisitMemRegion(const MemRegion *R) { return loc::MemRegionVal(R); }
1330 
1331  SVal VisitNonLocSymbolVal(nonloc::SymbolVal V) {
1332  // Simplification is much more costly than computing complexity.
1333  // For high complexity, it may be not worth it.
1334  return Visit(V.getSymbol());
1335  }
1336 
1337  SVal VisitSVal(SVal V) { return V; }
1338  };
1339 
1340  // A crude way of preventing this function from calling itself from evalBinOp.
1341  static bool isReentering = false;
1342  if (isReentering)
1343  return V;
1344 
1345  isReentering = true;
1346  SVal SimplifiedV = Simplifier(State).Visit(V);
1347  isReentering = false;
1348 
1349  return SimplifiedV;
1350 }
Represents a function declaration or definition.
Definition: Decl.h:1748
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T -> getSizeExpr()))
CanQualType VoidPtrTy
Definition: ASTContext.h:1042
A (possibly-)qualified type.
Definition: Type.h:643
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:94
const SymExpr * SymbolRef
SValBuilder * createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, ProgramStateManager &stateMgr)
QualType getPointeeType() const
If this is a pointer, ObjC object pointer, or block pointer, this returns the respective pointee...
Definition: Type.cpp:505
static bool isWithinConstantOverflowBounds(SymbolRef Sym, ProgramStateRef State)
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
const RecordDecl * getParent() const
Returns the parent of this field declaration, which is the struct in which this field is defined...
Definition: Decl.h:2789
Value representing integer constant.
Definition: SVals.h:379
long i
Definition: xmmintrin.h:1456
bool isAdditiveOp() const
Definition: Expr.h:3484
Symbolic value.
Definition: SymExpr.h:29
Represents a struct/union/class.
Definition: Decl.h:3619
const SymbolicRegion * getSymbolicBase() const
If this is a symbolic region, returns the region.
Definition: MemRegion.cpp:1219
static NonLoc doRearrangeUnchecked(ProgramStateRef State, BinaryOperator::Opcode Op, SymbolRef LSym, llvm::APSInt LInt, SymbolRef RSym, llvm::APSInt RInt)
static Opcode reverseComparisonOp(Opcode Opc)
Definition: Expr.h:3516
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:154
static bool isInRelation(BinaryOperator::Opcode Rel, SymbolRef Sym, llvm::APSInt Bound, ProgramStateRef State)
Value representing pointer-to-member.
Definition: SVals.h:524
LineState State
field_range fields() const
Definition: Decl.h:3810
Represents a member of a struct/union/class.
Definition: Decl.h:2605
bool isReferenceType() const
Definition: Type.h:6363
i32 captured_struct **param SharedsTy A type which contains references the shared variables *param Shareds Context with the list of shared variables from the p *TaskFunction *param Data Additional data for task generation like final * state
const SymExpr * getAsSymbolicExpression() const
getAsSymbolicExpression - If this Sval wraps a symbolic expression then return that expression...
Definition: SVals.cpp:137
bool isIntegralOrEnumerationType() const
Determine whether this type is an integral or enumeration type.
Definition: Type.h:6714
static bool isLocType(QualType T)
Definition: SVals.h:329
BinaryOperatorKind
static bool shouldRearrange(ProgramStateRef State, BinaryOperator::Opcode Op, SymbolRef Sym, llvm::APSInt Int, QualType Ty)
b
Definition: emmintrin.h:321
virtual QualType getType() const =0
static std::pair< SymbolRef, llvm::APSInt > decomposeSymbol(SymbolRef Sym, BasicValueFactory &BV)
static Opcode negateComparisonOp(Opcode Opc)
Definition: Expr.h:3503
unsigned getSubKind() const
Definition: SVals.h:119
SymbolicRegion - A special, "non-concrete" region.
Definition: MemRegion.h:763
#define V(N, I)
Definition: ASTContext.h:2912
static SVal getValue(SVal val, SValBuilder &svalBuilder)
bool isUnionType() const
Definition: Type.cpp:475
bool isNull() const
Return true if this QualType doesn&#39;t point to a type yet.
Definition: Type.h:708
Optional< T > getAs() const
Convert to the specified SVal type, returning None if this SVal is not of the desired type...
Definition: SVals.h:111
bool isComparisonOp() const
Definition: Expr.h:3498
r
Definition: emmintrin.h:563
FunctionCodeRegion - A region that represents code texts of function.
Definition: MemRegion.h:580
SVal - This represents a symbolic expression, which can be either an L-value or an R-value...
Definition: SVals.h:75
bool isSignedIntegerOrEnumerationType() const
Determines whether this is an integer type that is signed or an enumeration types whose underlying ty...
Definition: Type.cpp:1891
bool isAnyPointerType() const
Definition: Type.h:6355
Dataflow Directional Tag Classes.
bool isShiftOp() const
Definition: Expr.h:3486
bool isBooleanType() const
Definition: Type.h:6727
Represents symbolic expression that isn&#39;t a location.
Definition: SVals.h:349
unsigned getIntWidth(QualType T) const
T castAs() const
Convert to the specified SVal type, asserting that this SVal is of the desired type.
Definition: SVals.h:103
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:2079
CanQualType getCanonicalType(QualType T) const
Return the canonical (structural) type corresponding to the specified potentially non-canonical type ...
Definition: ASTContext.h:2280
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:14125
bool isVoidType() const
Definition: Type.h:6610
static Optional< NonLoc > tryRearrange(ProgramStateRef State, BinaryOperator::Opcode Op, NonLoc Lhs, NonLoc Rhs, QualType ResultTy)
__DEVICE__ int max(int __a, int __b)
static SVal evalBinOpFieldRegionFieldRegion(const FieldRegion *LeftFR, const FieldRegion *RightFR, BinaryOperator::Opcode op, QualType resultTy, SimpleSValBuilder &SVB)