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/* Generic hooks for the RTL middle-end.
Copyright (C) 2004, 2005, 2007, 2008 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 3, 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 COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#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;
/* Handle SUBREGs and hard REGs that were rejected by
simplify_gen_subreg. */
else if (REG_P (x) || GET_CODE (x) == SUBREG)
{
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)))
&& !reload_completed)
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 (const_rtx x ATTRIBUTE_UNUSED,
enum machine_mode mode ATTRIBUTE_UNUSED,
const_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 (const_rtx x ATTRIBUTE_UNUSED,
enum machine_mode mode ATTRIBUTE_UNUSED,
const_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;
}
bool
reg_truncated_to_mode_general (enum machine_mode mode ATTRIBUTE_UNUSED,
const_rtx x ATTRIBUTE_UNUSED)
{
return false;
}
/* 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_rtx;
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_rtx = adjust_address_nv (x, mode, offset);
if (! memory_address_p (mode, XEXP (new_rtx, 0)))
return 0;
return new_rtx;
}
else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode
&& validate_subreg (mode, GET_MODE (x), x,
subreg_lowpart_offset (mode, GET_MODE (x))))
return gen_lowpart_SUBREG (mode, x);
else
return 0;
}
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