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/* Generic hooks for the RTL middle-end.

   Copyright (C) 2004, 2005 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 2, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING.  If not, write to the Free

Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "rtl.h"

#include "rtlhooks-def.h"

#include "expr.h"

#include "recog.h"

/* For speed, we will copy the RTX hooks struct member-by-member

   instead of doing indirect calls.  For these reason, we initialize

   *two* struct rtl_hooks globals: rtl_hooks is the one that is used

   to actually call the hooks, while general_rtl_hooks is used

   to restore the hooks by passes that modify them.  */

const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER;

struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER;

rtx

gen_lowpart_general (enum machine_mode mode, rtx x)

{

  rtx result = gen_lowpart_common (mode, x);

  if (result)

    return result;

  else if (REG_P (x))

    {

      /* Must be a hard reg that's not valid in MODE.  */

      result = gen_lowpart_common (mode, copy_to_reg (x));

      gcc_assert (result != 0);

      return result;

    }

  else

    {

      int offset = 0;

      /* The only additional case we can do is MEM.  */

      gcc_assert (MEM_P (x));

      /* The following exposes the use of "x" to CSE.  */

      if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD

          && SCALAR_INT_MODE_P (GET_MODE (x))

          && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),

                                    GET_MODE_BITSIZE (GET_MODE (x)))

          && ! no_new_pseudos)

        return gen_lowpart_general (mode, force_reg (GET_MODE (x), x));

      if (WORDS_BIG_ENDIAN)

        offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)

                  - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));

      if (BYTES_BIG_ENDIAN)

        /* Adjust the address so that the address-after-the-data

           is unchanged.  */

        offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))

                   - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));

      return adjust_address (x, mode, offset);

    }

}

/* Similar to gen_lowpart, but cannot emit any instruction via

   copy_to_reg or force_reg.  Mainly used in simplify-rtx.c.  */

rtx

gen_lowpart_no_emit_general (enum machine_mode mode, rtx x)

{

  rtx result = gen_lowpart_if_possible (mode, x);

  if (result)

    return result;

  else

    return x;

}

rtx

reg_num_sign_bit_copies_general (rtx x ATTRIBUTE_UNUSED,

                                 enum machine_mode mode ATTRIBUTE_UNUSED,

                                 rtx known_x ATTRIBUTE_UNUSED,

                                 enum machine_mode known_mode ATTRIBUTE_UNUSED,

                                 unsigned int known_ret ATTRIBUTE_UNUSED,

                                 unsigned int *result ATTRIBUTE_UNUSED)

{

  return NULL;

}

rtx

reg_nonzero_bits_general (rtx x ATTRIBUTE_UNUSED,

                          enum machine_mode mode ATTRIBUTE_UNUSED,

                          rtx known_x ATTRIBUTE_UNUSED,

                          enum machine_mode known_mode ATTRIBUTE_UNUSED,

                          unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED,

                          unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED)

{

  return NULL;

}

/* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point

   number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the

   least-significant part of X.

   MODE specifies how big a part of X to return.

   If the requested operation cannot be done, 0 is returned.

   This is similar to gen_lowpart_general.  */

rtx

gen_lowpart_if_possible (enum machine_mode mode, rtx x)

{

  rtx result = gen_lowpart_common (mode, x);

  if (result)

    return result;

  else if (MEM_P (x))

    {

      /* This is the only other case we handle.  */

      int offset = 0;

      rtx new;

      if (WORDS_BIG_ENDIAN)

        offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)

                  - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));

      if (BYTES_BIG_ENDIAN)

        /* Adjust the address so that the address-after-the-data is

           unchanged.  */

        offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))

                   - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));

      new = adjust_address_nv (x, mode, offset);

      if (! memory_address_p (mode, XEXP (new, 0)))

        return 0;

      return new;

    }

  else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode)

    return gen_lowpart_SUBREG (mode, x);

  else

    return 0;

}