コード例 #1
0
ProgramStateRef SimpleConstraintManager::assumeSymRel(ProgramStateRef State,
                                                      const SymExpr *LHS,
                                                      BinaryOperator::Opcode Op,
                                                      const llvm::APSInt &Int) {
  assert(BinaryOperator::isComparisonOp(Op) &&
         "Non-comparison ops should be rewritten as comparisons to zero.");

  // Get the type used for calculating wraparound.
  BasicValueFactory &BVF = getBasicVals();
  APSIntType WraparoundType = BVF.getAPSIntType(LHS->getType());

  // We only handle simple comparisons of the form "$sym == constant"
  // or "($sym+constant1) == constant2".
  // The adjustment is "constant1" in the above expression. It's used to
  // "slide" the solution range around for modular arithmetic. For example,
  // x < 4 has the solution [0, 3]. x+2 < 4 has the solution [0-2, 3-2], which
  // in modular arithmetic is [0, 1] U [UINT_MAX-1, UINT_MAX]. It's up to
  // the subclasses of SimpleConstraintManager to handle the adjustment.
  SymbolRef Sym = LHS;
  llvm::APSInt Adjustment = WraparoundType.getZeroValue();
  computeAdjustment(Sym, Adjustment);

  // Convert the right-hand side integer as necessary.
  APSIntType ComparisonType = std::max(WraparoundType, APSIntType(Int));
  llvm::APSInt ConvertedInt = ComparisonType.convert(Int);

  // Prefer unsigned comparisons.
  if (ComparisonType.getBitWidth() == WraparoundType.getBitWidth() &&
      ComparisonType.isUnsigned() && !WraparoundType.isUnsigned())
    Adjustment.setIsSigned(false);

  switch (Op) {
  default:
    llvm_unreachable("invalid operation not caught by assertion above");

  case BO_EQ:
    return assumeSymEQ(State, Sym, ConvertedInt, Adjustment);

  case BO_NE:
    return assumeSymNE(State, Sym, ConvertedInt, Adjustment);

  case BO_GT:
    return assumeSymGT(State, Sym, ConvertedInt, Adjustment);

  case BO_GE:
    return assumeSymGE(State, Sym, ConvertedInt, Adjustment);

  case BO_LT:
    return assumeSymLT(State, Sym, ConvertedInt, Adjustment);

  case BO_LE:
    return assumeSymLE(State, Sym, ConvertedInt, Adjustment);
  } // end switch
}
コード例 #2
0
ProgramStateRef SimpleConstraintManager::assumeSymRel(ProgramStateRef state,
                                                     const SymExpr *LHS,
                                                     BinaryOperator::Opcode op,
                                                     const llvm::APSInt& Int) {
  assert(BinaryOperator::isComparisonOp(op) &&
         "Non-comparison ops should be rewritten as comparisons to zero.");

  BasicValueFactory &BVF = getBasicVals();
  ASTContext &Ctx = BVF.getContext();

  // Get the type used for calculating wraparound.
  APSIntType WraparoundType = BVF.getAPSIntType(LHS->getType(Ctx));

  // We only handle simple comparisons of the form "$sym == constant"
  // or "($sym+constant1) == constant2".
  // The adjustment is "constant1" in the above expression. It's used to
  // "slide" the solution range around for modular arithmetic. For example,
  // x < 4 has the solution [0, 3]. x+2 < 4 has the solution [0-2, 3-2], which
  // in modular arithmetic is [0, 1] U [UINT_MAX-1, UINT_MAX]. It's up to
  // the subclasses of SimpleConstraintManager to handle the adjustment.
  SymbolRef Sym = LHS;
  llvm::APSInt Adjustment = WraparoundType.getZeroValue();
  computeAdjustment(Sym, Adjustment);

  // Convert the right-hand side integer as necessary.
  APSIntType ComparisonType = std::max(WraparoundType, APSIntType(Int));
  llvm::APSInt ConvertedInt = ComparisonType.convert(Int);

  switch (op) {
  default:
    // No logic yet for other operators.  assume the constraint is feasible.
    return state;

  case BO_EQ:
    return assumeSymEQ(state, Sym, ConvertedInt, Adjustment);

  case BO_NE:
    return assumeSymNE(state, Sym, ConvertedInt, Adjustment);

  case BO_GT:
    return assumeSymGT(state, Sym, ConvertedInt, Adjustment);

  case BO_GE:
    return assumeSymGE(state, Sym, ConvertedInt, Adjustment);

  case BO_LT:
    return assumeSymLT(state, Sym, ConvertedInt, Adjustment);

  case BO_LE:
    return assumeSymLE(state, Sym, ConvertedInt, Adjustment);
  } // end switch
}
コード例 #3
0
ProgramStateRef
SimpleConstraintManager::assumeAuxForSymbol(ProgramStateRef State,
                                            SymbolRef Sym, bool Assumption) {
  BasicValueFactory &BVF = getBasicVals();
  QualType T = Sym->getType();

  // None of the constraint solvers currently support non-integer types.
  if (!T->isIntegralOrEnumerationType())
    return State;

  const llvm::APSInt &zero = BVF.getValue(0, T);
  if (Assumption)
    return assumeSymNE(State, Sym, zero, zero);
  else
    return assumeSymEQ(State, Sym, zero, zero);
}
コード例 #4
0
ProgramStateRef
RangedConstraintManager::assumeSymUnsupported(ProgramStateRef State,
                                              SymbolRef Sym, bool Assumption) {
  BasicValueFactory &BVF = getBasicVals();
  QualType T = Sym->getType();

  // Non-integer types are not supported.
  if (!T->isIntegralOrEnumerationType())
    return State;

  // Reverse the operation and add directly to state.
  const llvm::APSInt &Zero = BVF.getValue(0, T);
  if (Assumption)
    return assumeSymNE(State, Sym, Zero, Zero);
  else
    return assumeSymEQ(State, Sym, Zero, Zero);
}
コード例 #5
0
const ProgramState *SimpleConstraintManager::assumeAux(const ProgramState *state,
                                                  Loc Cond, bool Assumption) {

  BasicValueFactory &BasicVals = state->getBasicVals();

  switch (Cond.getSubKind()) {
  default:
    assert (false && "'Assume' not implemented for this Loc.");
    return state;

  case loc::MemRegionKind: {
    // FIXME: Should this go into the storemanager?

    const MemRegion *R = cast<loc::MemRegionVal>(Cond).getRegion();
    const SubRegion *SubR = dyn_cast<SubRegion>(R);

    while (SubR) {
      // FIXME: now we only find the first symbolic region.
      if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SubR)) {
        const llvm::APSInt &zero = BasicVals.getZeroWithPtrWidth();
        if (Assumption)
          return assumeSymNE(state, SymR->getSymbol(), zero, zero);
        else
          return assumeSymEQ(state, SymR->getSymbol(), zero, zero);
      }
      SubR = dyn_cast<SubRegion>(SubR->getSuperRegion());
    }

    // FALL-THROUGH.
  }

  case loc::GotoLabelKind:
    return Assumption ? state : NULL;

  case loc::ConcreteIntKind: {
    bool b = cast<loc::ConcreteInt>(Cond).getValue() != 0;
    bool isFeasible = b ? Assumption : !Assumption;
    return isFeasible ? state : NULL;
  }
  } // end switch
}
コード例 #6
0
const ProgramState *SimpleConstraintManager::assumeSymRel(const ProgramState *state,
                                                     const SymExpr *LHS,
                                                     BinaryOperator::Opcode op,
                                                     const llvm::APSInt& Int) {
  assert(BinaryOperator::isComparisonOp(op) &&
         "Non-comparison ops should be rewritten as comparisons to zero.");

   // We only handle simple comparisons of the form "$sym == constant"
   // or "($sym+constant1) == constant2".
   // The adjustment is "constant1" in the above expression. It's used to
   // "slide" the solution range around for modular arithmetic. For example,
   // x < 4 has the solution [0, 3]. x+2 < 4 has the solution [0-2, 3-2], which
   // in modular arithmetic is [0, 1] U [UINT_MAX-1, UINT_MAX]. It's up to
   // the subclasses of SimpleConstraintManager to handle the adjustment.
   llvm::APSInt Adjustment;

  // First check if the LHS is a simple symbol reference.
  SymbolRef Sym = dyn_cast<SymbolData>(LHS);
  if (Sym) {
    Adjustment = 0;
  } else {
    // Next, see if it's a "($sym+constant1)" expression.
    const SymIntExpr *SE = dyn_cast<SymIntExpr>(LHS);

    // We don't handle "($sym1+$sym2)".
    // Give up and assume the constraint is feasible.
    if (!SE)
      return state;

    // We don't handle "(<expr>+constant1)".
    // Give up and assume the constraint is feasible.
    Sym = dyn_cast<SymbolData>(SE->getLHS());
    if (!Sym)
      return state;

    // Get the constant out of the expression "($sym+constant1)".
    switch (SE->getOpcode()) {
    case BO_Add:
      Adjustment = SE->getRHS();
      break;
    case BO_Sub:
      Adjustment = -SE->getRHS();
      break;
    default:
      // We don't handle non-additive operators.
      // Give up and assume the constraint is feasible.
      return state;
    }
  }

  // FIXME: This next section is a hack. It silently converts the integers to
  // be of the same type as the symbol, which is not always correct. Really the
  // comparisons should be performed using the Int's type, then mapped back to
  // the symbol's range of values.
  ProgramStateManager &StateMgr = state->getStateManager();
  ASTContext &Ctx = StateMgr.getContext();

  QualType T = Sym->getType(Ctx);
  assert(T->isIntegerType() || Loc::isLocType(T));
  unsigned bitwidth = Ctx.getTypeSize(T);
  bool isSymUnsigned 
    = T->isUnsignedIntegerOrEnumerationType() || Loc::isLocType(T);

  // Convert the adjustment.
  Adjustment.setIsUnsigned(isSymUnsigned);
  Adjustment = Adjustment.extOrTrunc(bitwidth);

  // Convert the right-hand side integer.
  llvm::APSInt ConvertedInt(Int, isSymUnsigned);
  ConvertedInt = ConvertedInt.extOrTrunc(bitwidth);

  switch (op) {
  default:
    // No logic yet for other operators.  assume the constraint is feasible.
    return state;

  case BO_EQ:
    return assumeSymEQ(state, Sym, ConvertedInt, Adjustment);

  case BO_NE:
    return assumeSymNE(state, Sym, ConvertedInt, Adjustment);

  case BO_GT:
    return assumeSymGT(state, Sym, ConvertedInt, Adjustment);

  case BO_GE:
    return assumeSymGE(state, Sym, ConvertedInt, Adjustment);

  case BO_LT:
    return assumeSymLT(state, Sym, ConvertedInt, Adjustment);

  case BO_LE:
    return assumeSymLE(state, Sym, ConvertedInt, Adjustment);
  } // end switch
}
コード例 #7
0
const ProgramState *SimpleConstraintManager::assumeAux(const ProgramState *state,
                                                  NonLoc Cond,
                                                  bool Assumption) {

  // We cannot reason about SymSymExprs,
  // and can only reason about some SymIntExprs.
  if (!canReasonAbout(Cond)) {
    // Just return the current state indicating that the path is feasible.
    // This may be an over-approximation of what is possible.
    return state;
  }

  BasicValueFactory &BasicVals = state->getBasicVals();
  SymbolManager &SymMgr = state->getSymbolManager();

  switch (Cond.getSubKind()) {
  default:
    assert(false && "'Assume' not implemented for this NonLoc");

  case nonloc::SymbolValKind: {
    nonloc::SymbolVal& SV = cast<nonloc::SymbolVal>(Cond);
    SymbolRef sym = SV.getSymbol();
    QualType T =  SymMgr.getType(sym);
    const llvm::APSInt &zero = BasicVals.getValue(0, T);
    if (Assumption)
      return assumeSymNE(state, sym, zero, zero);
    else
      return assumeSymEQ(state, sym, zero, zero);
  }

  case nonloc::SymExprValKind: {
    nonloc::SymExprVal V = cast<nonloc::SymExprVal>(Cond);

    // For now, we only handle expressions whose RHS is an integer.
    // All other expressions are assumed to be feasible.
    const SymIntExpr *SE = dyn_cast<SymIntExpr>(V.getSymbolicExpression());
    if (!SE)
      return state;

    BinaryOperator::Opcode op = SE->getOpcode();
    // Implicitly compare non-comparison expressions to 0.
    if (!BinaryOperator::isComparisonOp(op)) {
      QualType T = SymMgr.getType(SE);
      const llvm::APSInt &zero = BasicVals.getValue(0, T);
      op = (Assumption ? BO_NE : BO_EQ);
      return assumeSymRel(state, SE, op, zero);
    }

    // From here on out, op is the real comparison we'll be testing.
    if (!Assumption)
      op = NegateComparison(op);
  
    return assumeSymRel(state, SE->getLHS(), op, SE->getRHS());
  }

  case nonloc::ConcreteIntKind: {
    bool b = cast<nonloc::ConcreteInt>(Cond).getValue() != 0;
    bool isFeasible = b ? Assumption : !Assumption;
    return isFeasible ? state : NULL;
  }

  case nonloc::LocAsIntegerKind:
    return assumeAux(state, cast<nonloc::LocAsInteger>(Cond).getLoc(),
                     Assumption);
  } // end switch
}