boolbv_typecast.cpp

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/*******************************************************************\
 
Module:
 
Author: Daniel Kroening, kroening@kroening.com
 
\*******************************************************************/
 
#include <util/bitvector_types.h>
#include <util/c_types.h>
#include <util/namespace.h>
 
#include <solvers/floatbv/float_utils.h>
 
#include "boolbv.h"
#include "boolbv_type.h"
#include "c_bit_field_replacement_type.h"
 
bvt boolbvt::convert_bv_typecast(const typecast_exprt &expr)
{
  const exprt &op = expr.op();
  const bvt &op_bv = convert_bv(op);
 
  bvt bv;
 
  if(type_conversion(op.type(), op_bv, expr.type(), bv))
    return conversion_failed(expr);
 
  return bv;
}
 
bool boolbvt::type_conversion(
  const typet &src_type,
  const bvt &src,
  const typet &dest_type,
  bvt &dest)
{
  bvtypet dest_bvtype = get_bvtype(dest_type);
  bvtypet src_bvtype = get_bvtype(src_type);
 
  if(src_bvtype == bvtypet::IS_C_BIT_FIELD)
    return type_conversion(
      c_bit_field_replacement_type(to_c_bit_field_type(src_type), ns),
      src,
      dest_type,
      dest);
 
  if(dest_bvtype == bvtypet::IS_C_BIT_FIELD)
    return type_conversion(
      src_type,
      src,
      c_bit_field_replacement_type(to_c_bit_field_type(dest_type), ns),
      dest);
 
  std::size_t src_width = src.size();
  std::size_t dest_width = boolbv_width(dest_type);
 
  if(dest_width == 0 || src_width == 0)
    return true;
 
  dest.clear();
  dest.reserve(dest_width);
 
  if(dest_type.id() == ID_complex)
  {
    if(src_type == to_complex_type(dest_type).subtype())
    {
      dest.insert(dest.end(), src.begin(), src.end());
 
      // pad with zeros
      for(std::size_t i = src.size(); i < dest_width; i++)
        dest.push_back(const_literal(false));
 
      return false;
    }
    else if(src_type.id() == ID_complex)
    {
      // recursively do both halfs
      bvt lower, upper, lower_res, upper_res;
      lower.assign(src.begin(), src.begin() + src.size() / 2);
      upper.assign(src.begin() + src.size() / 2, src.end());
      type_conversion(
        to_complex_type(src_type).subtype(),
        lower,
        to_complex_type(dest_type).subtype(),
        lower_res);
      type_conversion(
        to_complex_type(src_type).subtype(),
        upper,
        to_complex_type(dest_type).subtype(),
        upper_res);
      INVARIANT(
        lower_res.size() + upper_res.size() == dest_width,
        "lower result bitvector size plus upper result bitvector size shall "
        "equal the destination bitvector size");
      dest = lower_res;
      dest.insert(dest.end(), upper_res.begin(), upper_res.end());
      return false;
    }
  }
 
  if(src_type.id() == ID_complex)
  {
    INVARIANT(
      dest_type.id() == ID_complex,
      "destination type shall be of complex type when source type is of "
      "complex type");
    if(
      dest_type.id() == ID_signedbv || dest_type.id() == ID_unsignedbv ||
      dest_type.id() == ID_floatbv || dest_type.id() == ID_fixedbv ||
      dest_type.id() == ID_c_enum || dest_type.id() == ID_c_enum_tag ||
      dest_type.id() == ID_bool)
    {
      // A cast from complex x to real T
      // is (T) __real__ x.
      bvt tmp_src(src);
      tmp_src.resize(src.size() / 2); // cut off imag part
      return type_conversion(
        to_complex_type(src_type).subtype(), tmp_src, dest_type, dest);
    }
  }
 
  switch(dest_bvtype)
  {
  case bvtypet::IS_RANGE:
    if(
      src_bvtype == bvtypet::IS_UNSIGNED || src_bvtype == bvtypet::IS_SIGNED ||
      src_bvtype == bvtypet::IS_C_BOOL)
    {
      mp_integer dest_from = to_range_type(dest_type).get_from();
 
      if(dest_from == 0)
      {
        // do zero extension
        dest.resize(dest_width);
        for(std::size_t i = 0; i < dest.size(); i++)
          dest[i] = (i < src.size() ? src[i] : const_literal(false));
 
        return false;
      }
    }
    else if(src_bvtype == bvtypet::IS_RANGE) // range to range
    {
      mp_integer src_from = to_range_type(src_type).get_from();
      mp_integer dest_from = to_range_type(dest_type).get_from();
 
      if(dest_from == src_from)
      {
        // do zero extension, if needed
        dest = bv_utils.zero_extension(src, dest_width);
        return false;
      }
      else
      {
        // need to do arithmetic: add src_from-dest_from
        mp_integer offset = src_from - dest_from;
        dest = bv_utils.add(
          bv_utils.zero_extension(src, dest_width),
          bv_utils.build_constant(offset, dest_width));
      }
 
      return false;
    }
    break;
 
  case bvtypet::IS_FLOAT: // to float
  {
    float_utilst float_utils(prop);
 
    switch(src_bvtype)
    {
    case bvtypet::IS_FLOAT: // float to float
      // we don't have a rounding mode here,
      // which is why we refuse.
      break;
 
    case bvtypet::IS_SIGNED: // signed to float
    case bvtypet::IS_C_ENUM:
      float_utils.spec = ieee_float_spect(to_floatbv_type(dest_type));
      dest = float_utils.from_signed_integer(src);
      return false;
 
    case bvtypet::IS_UNSIGNED: // unsigned to float
    case bvtypet::IS_C_BOOL:   // _Bool to float
      float_utils.spec = ieee_float_spect(to_floatbv_type(dest_type));
      dest = float_utils.from_unsigned_integer(src);
      return false;
 
    case bvtypet::IS_BV:
      INVARIANT(src_width >= dest_width, "cannot extend bv-typed bitvector");
      dest = src;
      if(dest_width < src_width)
        dest.resize(dest_width);
      return false;
 
    case bvtypet::IS_C_BIT_FIELD:
    case bvtypet::IS_UNKNOWN:
    case bvtypet::IS_RANGE:
    case bvtypet::IS_VERILOG_UNSIGNED:
    case bvtypet::IS_VERILOG_SIGNED:
    case bvtypet::IS_FIXED:
      if(src_type.id() == ID_bool)
      {
        // bool to float
 
        // build a one
        ieee_floatt f(to_floatbv_type(dest_type));
        f.from_integer(1);
 
        dest = convert_bv(f.to_expr());
 
        INVARIANT(
          src_width == 1, "bitvector of type boolean shall have width one");
 
        for(auto &literal : dest)
          literal = prop.land(literal, src[0]);
 
        return false;
      }
    }
  }
  break;
 
  case bvtypet::IS_FIXED:
    if(src_bvtype == bvtypet::IS_FIXED)
    {
      // fixed to fixed
 
      std::size_t dest_fraction_bits =
        to_fixedbv_type(dest_type).get_fraction_bits();
      std::size_t dest_int_bits = dest_width - dest_fraction_bits;
      std::size_t op_fraction_bits =
        to_fixedbv_type(src_type).get_fraction_bits();
      std::size_t op_int_bits = src_width - op_fraction_bits;
 
      dest.resize(dest_width);
 
      // i == position after dot
      // i == 0: first position after dot
 
      for(std::size_t i = 0; i < dest_fraction_bits; i++)
      {
        // position in bv
        std::size_t p = dest_fraction_bits - i - 1;
 
        if(i < op_fraction_bits)
          dest[p] = src[op_fraction_bits - i - 1];
        else
          dest[p] = const_literal(false); // zero padding
      }
 
      for(std::size_t i = 0; i < dest_int_bits; i++)
      {
        // position in bv
        std::size_t p = dest_fraction_bits + i;
        INVARIANT(p < dest_width, "bit index shall be within bounds");
 
        if(i < op_int_bits)
          dest[p] = src[i + op_fraction_bits];
        else
          dest[p] = src[src_width - 1]; // sign extension
      }
 
      return false;
    }
    else if(src_bvtype == bvtypet::IS_BV)
    {
      INVARIANT(src_width >= dest_width, "cannot extend bv-typed bitvector");
      dest = src;
      if(dest_width < src_width)
        dest.resize(dest_width);
      return false;
    }
    else if(
      src_bvtype == bvtypet::IS_UNSIGNED || src_bvtype == bvtypet::IS_SIGNED ||
      src_bvtype == bvtypet::IS_C_BOOL || src_bvtype == bvtypet::IS_C_ENUM)
    {
      // integer to fixed
 
      std::size_t dest_fraction_bits =
        to_fixedbv_type(dest_type).get_fraction_bits();
 
      for(std::size_t i = 0; i < dest_fraction_bits; i++)
        dest.push_back(const_literal(false)); // zero padding
 
      for(std::size_t i = 0; i < dest_width - dest_fraction_bits; i++)
      {
        literalt l;
 
        if(i < src_width)
          l = src[i];
        else
        {
          if(
            src_bvtype == bvtypet::IS_SIGNED ||
            src_bvtype == bvtypet::IS_C_ENUM)
            l = src[src_width - 1]; // sign extension
          else
            l = const_literal(false); // zero extension
        }
 
        dest.push_back(l);
      }
 
      return false;
    }
    else if(src_type.id() == ID_bool)
    {
      // bool to fixed
      std::size_t fraction_bits =
        to_fixedbv_type(dest_type).get_fraction_bits();
 
      INVARIANT(
        src_width == 1, "bitvector of type boolean shall have width one");
 
      for(std::size_t i = 0; i < dest_width; i++)
      {
        if(i == fraction_bits)
          dest.push_back(src[0]);
        else
          dest.push_back(const_literal(false));
      }
 
      return false;
    }
    break;
 
  case bvtypet::IS_UNSIGNED:
  case bvtypet::IS_SIGNED:
  case bvtypet::IS_C_ENUM:
  {
    switch(src_bvtype)
    {
    case bvtypet::IS_FLOAT: // float to integer
      // we don't have a rounding mode here,
      // which is why we refuse.
      break;
 
    case bvtypet::IS_FIXED: // fixed to integer
    {
      std::size_t op_fraction_bits =
        to_fixedbv_type(src_type).get_fraction_bits();
 
      for(std::size_t i = 0; i < dest_width; i++)
      {
        if(i < src_width - op_fraction_bits)
          dest.push_back(src[i + op_fraction_bits]);
        else
        {
          if(dest_bvtype == bvtypet::IS_SIGNED)
            dest.push_back(src[src_width - 1]); // sign extension
          else
            dest.push_back(const_literal(false)); // zero extension
        }
      }
 
      // we might need to round up in case of negative numbers
      // e.g., (int)(-1.00001)==1
 
      bvt fraction_bits_bv = src;
      fraction_bits_bv.resize(op_fraction_bits);
      literalt round_up = prop.land(prop.lor(fraction_bits_bv), src.back());
 
      dest = bv_utils.incrementer(dest, round_up);
 
      return false;
    }
 
    case bvtypet::IS_UNSIGNED: // integer to integer
    case bvtypet::IS_SIGNED:
    case bvtypet::IS_C_ENUM:
    case bvtypet::IS_C_BOOL:
    {
      // We do sign extension for any source type
      // that is signed, independently of the
      // destination type.
      // E.g., ((short)(ulong)(short)-1)==-1
      bool sign_extension =
        src_bvtype == bvtypet::IS_SIGNED || src_bvtype == bvtypet::IS_C_ENUM;
 
      for(std::size_t i = 0; i < dest_width; i++)
      {
        if(i < src_width)
          dest.push_back(src[i]);
        else if(sign_extension)
          dest.push_back(src[src_width - 1]); // sign extension
        else
          dest.push_back(const_literal(false));
      }
 
      return false;
    }
    // verilog_unsignedbv to signed/unsigned/enum
    case bvtypet::IS_VERILOG_UNSIGNED:
    {
      for(std::size_t i = 0; i < dest_width; i++)
      {
        std::size_t src_index = i * 2; // we take every second bit
 
        if(src_index < src_width)
          dest.push_back(src[src_index]);
        else // always zero-extend
          dest.push_back(const_literal(false));
      }
 
      return false;
    }
    break;
 
    case bvtypet::IS_VERILOG_SIGNED: // verilog_signedbv to signed/unsigned/enum
    {
      for(std::size_t i = 0; i < dest_width; i++)
      {
        std::size_t src_index = i * 2; // we take every second bit
 
        if(src_index < src_width)
          dest.push_back(src[src_index]);
        else // always sign-extend
          dest.push_back(src.back());
      }
 
      return false;
    }
    break;
 
    case bvtypet::IS_BV:
      INVARIANT(src_width >= dest_width, "cannot extend bv-typed bitvector");
      dest = src;
      if(dest_width < src_width)
        dest.resize(dest_width);
      return false;
 
    case bvtypet::IS_RANGE:
    case bvtypet::IS_C_BIT_FIELD:
    case bvtypet::IS_UNKNOWN:
      if(src_type.id() == ID_bool)
      {
        // bool to integer
 
        INVARIANT(
          src_width == 1, "bitvector of type boolean shall have width one");
 
        for(std::size_t i = 0; i < dest_width; i++)
        {
          if(i == 0)
            dest.push_back(src[0]);
          else
            dest.push_back(const_literal(false));
        }
 
        return false;
      }
    }
    break;
  }
 
  case bvtypet::IS_VERILOG_UNSIGNED:
    if(
      src_bvtype == bvtypet::IS_UNSIGNED || src_bvtype == bvtypet::IS_C_BOOL ||
      src_type.id() == ID_bool)
    {
      for(std::size_t i = 0, j = 0; i < dest_width; i += 2, j++)
      {
        if(j < src_width)
          dest.push_back(src[j]);
        else
          dest.push_back(const_literal(false));
 
        dest.push_back(const_literal(false));
      }
 
      return false;
    }
    else if(src_bvtype == bvtypet::IS_SIGNED)
    {
      for(std::size_t i = 0, j = 0; i < dest_width; i += 2, j++)
      {
        if(j < src_width)
          dest.push_back(src[j]);
        else
          dest.push_back(src.back());
 
        dest.push_back(const_literal(false));
      }
 
      return false;
    }
    else if(src_bvtype == bvtypet::IS_VERILOG_UNSIGNED)
    {
      // verilog_unsignedbv to verilog_unsignedbv
      dest = src;
 
      if(dest_width < src_width)
        dest.resize(dest_width);
      else
      {
        dest = src;
        while(dest.size() < dest_width)
        {
          dest.push_back(const_literal(false));
          dest.push_back(const_literal(false));
        }
      }
      return false;
    }
    break;
 
  case bvtypet::IS_BV:
    INVARIANT(src_width >= dest_width, "cannot extend bv-typed bitvector");
    dest = src;
    if(dest_width < src_width)
      dest.resize(dest_width);
    return false;
 
  case bvtypet::IS_C_BOOL:
    dest.resize(dest_width, const_literal(false));
 
    if(src_bvtype == bvtypet::IS_FLOAT)
    {
      float_utilst float_utils(prop, to_floatbv_type(src_type));
      dest[0] = !float_utils.is_zero(src);
    }
    else if(src_bvtype == bvtypet::IS_C_BOOL)
      dest[0] = src[0];
    else
      dest[0] = !bv_utils.is_zero(src);
 
    return false;
 
  case bvtypet::IS_C_BIT_FIELD:
  case bvtypet::IS_UNKNOWN:
  case bvtypet::IS_VERILOG_SIGNED:
    if(dest_type.id() == ID_array)
    {
      if(src_width == dest_width)
      {
        dest = src;
        return false;
      }
    }
    else if(dest_type.id() == ID_struct || dest_type.id() == ID_struct_tag)
    {
      const struct_typet &dest_struct =
        dest_type.id() == ID_struct_tag
          ? ns.follow_tag(to_struct_tag_type(dest_type))
          : to_struct_type(dest_type);
 
      if(src_type.id() == ID_struct || src_type.id() == ID_struct_tag)
      {
        // we do subsets
 
        dest.resize(dest_width, const_literal(false));
 
        const struct_typet &op_struct =
          src_type.id() == ID_struct_tag
            ? ns.follow_tag(to_struct_tag_type(src_type))
            : to_struct_type(src_type);
 
        const struct_typet::componentst &dest_comp = dest_struct.components();
 
        const struct_typet::componentst &op_comp = op_struct.components();
 
        // build offset maps
        const offset_mapt op_offsets = build_offset_map(op_struct);
        const offset_mapt dest_offsets = build_offset_map(dest_struct);
 
        // build name map
        typedef std::map<irep_idt, std::size_t> op_mapt;
        op_mapt op_map;
 
        for(std::size_t i = 0; i < op_comp.size(); i++)
          op_map[op_comp[i].get_name()] = i;
 
        // now gather required fields
        for(std::size_t i = 0; i < dest_comp.size(); i++)
        {
          std::size_t offset = dest_offsets[i];
          std::size_t comp_width = boolbv_width(dest_comp[i].type());
          if(comp_width == 0)
            continue;
 
          op_mapt::const_iterator it = op_map.find(dest_comp[i].get_name());
 
          if(it == op_map.end())
          {
            // not found
 
            // filling with free variables
            for(std::size_t j = 0; j < comp_width; j++)
              dest[offset + j] = prop.new_variable();
          }
          else
          {
            // found
            if(dest_comp[i].type() != dest_comp[it->second].type())
            {
              // filling with free variables
              for(std::size_t j = 0; j < comp_width; j++)
                dest[offset + j] = prop.new_variable();
            }
            else
            {
              std::size_t op_offset = op_offsets[it->second];
              for(std::size_t j = 0; j < comp_width; j++)
                dest[offset + j] = src[op_offset + j];
            }
          }
        }
 
        return false;
      }
    }
  }
 
  return true;
}
 
literalt boolbvt::convert_typecast(const typecast_exprt &expr)
{
  if(expr.op().type().id() == ID_range)
  {
    mp_integer from = string2integer(expr.op().type().get_string(ID_from));
    mp_integer to = string2integer(expr.op().type().get_string(ID_to));
 
    if(from == 1 && to == 1)
      return const_literal(true);
    else if(from == 0 && to == 0)
      return const_literal(false);
  }
 
  const bvt &bv = convert_bv(expr.op());
 
  if(!bv.empty())
    return prop.lor(bv);
 
  return SUB::convert_rest(expr);
}