Exemplo n.º 1
0
const GRState*
SimpleConstraintManager::AssumeSymInt(const GRState* St, bool Assumption,
                                      const SymIntExpr *SE, bool& isFeasible) {


  // Here we assume that LHS is a symbol.  This is consistent with the
  // rest of the constraint manager logic.
  SymbolRef Sym = cast<SymbolData>(SE->getLHS());
  const llvm::APSInt &Int = SE->getRHS();
  
  switch (SE->getOpcode()) {
  default:
    // No logic yet for other operators.
    isFeasible = true;
    return St;

  case BinaryOperator::EQ:
    return Assumption ? AssumeSymEQ(St, Sym, Int, isFeasible)
                      : AssumeSymNE(St, Sym, Int, isFeasible);

  case BinaryOperator::NE:
    return Assumption ? AssumeSymNE(St, Sym, Int, isFeasible)
                      : AssumeSymEQ(St, Sym, Int, isFeasible);

  case BinaryOperator::GT:
    return Assumption ? AssumeSymGT(St, Sym, Int, isFeasible)
                      : AssumeSymLE(St, Sym, Int, isFeasible);

  case BinaryOperator::GE:
    return Assumption ? AssumeSymGE(St, Sym, Int, isFeasible)
                      : AssumeSymLT(St, Sym, Int, isFeasible);

  case BinaryOperator::LT:
    return Assumption ? AssumeSymLT(St, Sym, Int, isFeasible)
                      : AssumeSymGE(St, Sym, Int, isFeasible);
      
  case BinaryOperator::LE:
      return Assumption ? AssumeSymLE(St, Sym, Int, isFeasible)
                        : AssumeSymGT(St, Sym, Int, isFeasible);
  } // end switch
}
Exemplo n.º 2
0
const GRState *SimpleConstraintManager::AssumeSymRel(const GRState *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.
  GRStateManager &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->isUnsignedIntegerType() || Loc::IsLocType(T);

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

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