forked from illumos/gcc
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lower-subreg.c
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lower-subreg.c
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/* Decompose multiword subregs.
Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
Contributed by Richard Henderson <rth@redhat.com>
Ian Lance Taylor <iant@google.com>
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 "machmode.h"
#include "tm.h"
#include "rtl.h"
#include "tm_p.h"
#include "timevar.h"
#include "flags.h"
#include "insn-config.h"
#include "obstack.h"
#include "basic-block.h"
#include "recog.h"
#include "bitmap.h"
#include "expr.h"
#include "except.h"
#include "regs.h"
#include "tree-pass.h"
#include "df.h"
#ifdef STACK_GROWS_DOWNWARD
# undef STACK_GROWS_DOWNWARD
# define STACK_GROWS_DOWNWARD 1
#else
# define STACK_GROWS_DOWNWARD 0
#endif
DEF_VEC_P (bitmap);
DEF_VEC_ALLOC_P (bitmap,heap);
/* Decompose multi-word pseudo-registers into individual
pseudo-registers when possible. This is possible when all the uses
of a multi-word register are via SUBREG, or are copies of the
register to another location. Breaking apart the register permits
more CSE and permits better register allocation. */
/* Bit N in this bitmap is set if regno N is used in a context in
which we can decompose it. */
static bitmap decomposable_context;
/* Bit N in this bitmap is set if regno N is used in a context in
which it can not be decomposed. */
static bitmap non_decomposable_context;
/* Bit N in the bitmap in element M of this array is set if there is a
copy from reg M to reg N. */
static VEC(bitmap,heap) *reg_copy_graph;
/* Return whether X is a simple object which we can take a word_mode
subreg of. */
static bool
simple_move_operand (rtx x)
{
if (GET_CODE (x) == SUBREG)
x = SUBREG_REG (x);
if (!OBJECT_P (x))
return false;
if (GET_CODE (x) == LABEL_REF
|| GET_CODE (x) == SYMBOL_REF
|| GET_CODE (x) == HIGH
|| GET_CODE (x) == CONST)
return false;
if (MEM_P (x)
&& (MEM_VOLATILE_P (x)
|| mode_dependent_address_p (XEXP (x, 0))))
return false;
return true;
}
/* If INSN is a single set between two objects, return the single set.
Such an insn can always be decomposed. INSN should have been
passed to recog and extract_insn before this is called. */
static rtx
simple_move (rtx insn)
{
rtx x;
rtx set;
enum machine_mode mode;
if (recog_data.n_operands != 2)
return NULL_RTX;
set = single_set (insn);
if (!set)
return NULL_RTX;
x = SET_DEST (set);
if (x != recog_data.operand[0] && x != recog_data.operand[1])
return NULL_RTX;
if (!simple_move_operand (x))
return NULL_RTX;
x = SET_SRC (set);
if (x != recog_data.operand[0] && x != recog_data.operand[1])
return NULL_RTX;
/* For the src we can handle ASM_OPERANDS, and it is beneficial for
things like x86 rdtsc which returns a DImode value. */
if (GET_CODE (x) != ASM_OPERANDS
&& !simple_move_operand (x))
return NULL_RTX;
/* We try to decompose in integer modes, to avoid generating
inefficient code copying between integer and floating point
registers. That means that we can't decompose if this is a
non-integer mode for which there is no integer mode of the same
size. */
mode = GET_MODE (SET_SRC (set));
if (!SCALAR_INT_MODE_P (mode)
&& (mode_for_size (GET_MODE_SIZE (mode) * BITS_PER_UNIT, MODE_INT, 0)
== BLKmode))
return NULL_RTX;
/* Reject PARTIAL_INT modes. They are used for processor specific
purposes and it's probably best not to tamper with them. */
if (GET_MODE_CLASS (mode) == MODE_PARTIAL_INT)
return NULL_RTX;
return set;
}
/* If SET is a copy from one multi-word pseudo-register to another,
record that in reg_copy_graph. Return whether it is such a
copy. */
static bool
find_pseudo_copy (rtx set)
{
rtx dest = SET_DEST (set);
rtx src = SET_SRC (set);
unsigned int rd, rs;
bitmap b;
if (!REG_P (dest) || !REG_P (src))
return false;
rd = REGNO (dest);
rs = REGNO (src);
if (HARD_REGISTER_NUM_P (rd) || HARD_REGISTER_NUM_P (rs))
return false;
if (GET_MODE_SIZE (GET_MODE (dest)) <= UNITS_PER_WORD)
return false;
b = VEC_index (bitmap, reg_copy_graph, rs);
if (b == NULL)
{
b = BITMAP_ALLOC (NULL);
VEC_replace (bitmap, reg_copy_graph, rs, b);
}
bitmap_set_bit (b, rd);
return true;
}
/* Look through the registers in DECOMPOSABLE_CONTEXT. For each case
where they are copied to another register, add the register to
which they are copied to DECOMPOSABLE_CONTEXT. Use
NON_DECOMPOSABLE_CONTEXT to limit this--we don't bother to track
copies of registers which are in NON_DECOMPOSABLE_CONTEXT. */
static void
propagate_pseudo_copies (void)
{
bitmap queue, propagate;
queue = BITMAP_ALLOC (NULL);
propagate = BITMAP_ALLOC (NULL);
bitmap_copy (queue, decomposable_context);
do
{
bitmap_iterator iter;
unsigned int i;
bitmap_clear (propagate);
EXECUTE_IF_SET_IN_BITMAP (queue, 0, i, iter)
{
bitmap b = VEC_index (bitmap, reg_copy_graph, i);
if (b)
bitmap_ior_and_compl_into (propagate, b, non_decomposable_context);
}
bitmap_and_compl (queue, propagate, decomposable_context);
bitmap_ior_into (decomposable_context, propagate);
}
while (!bitmap_empty_p (queue));
BITMAP_FREE (queue);
BITMAP_FREE (propagate);
}
/* A pointer to one of these values is passed to
find_decomposable_subregs via for_each_rtx. */
enum classify_move_insn
{
/* Not a simple move from one location to another. */
NOT_SIMPLE_MOVE,
/* A simple move from one pseudo-register to another. */
SIMPLE_PSEUDO_REG_MOVE,
/* A simple move involving a non-pseudo-register. */
SIMPLE_MOVE
};
/* This is called via for_each_rtx. If we find a SUBREG which we
could use to decompose a pseudo-register, set a bit in
DECOMPOSABLE_CONTEXT. If we find an unadorned register which is
not a simple pseudo-register copy, DATA will point at the type of
move, and we set a bit in DECOMPOSABLE_CONTEXT or
NON_DECOMPOSABLE_CONTEXT as appropriate. */
static int
find_decomposable_subregs (rtx *px, void *data)
{
enum classify_move_insn *pcmi = (enum classify_move_insn *) data;
rtx x = *px;
if (x == NULL_RTX)
return 0;
if (GET_CODE (x) == SUBREG)
{
rtx inner = SUBREG_REG (x);
unsigned int regno, outer_size, inner_size, outer_words, inner_words;
if (!REG_P (inner))
return 0;
regno = REGNO (inner);
if (HARD_REGISTER_NUM_P (regno))
return -1;
outer_size = GET_MODE_SIZE (GET_MODE (x));
inner_size = GET_MODE_SIZE (GET_MODE (inner));
outer_words = (outer_size + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
inner_words = (inner_size + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
/* We only try to decompose single word subregs of multi-word
registers. When we find one, we return -1 to avoid iterating
over the inner register.
??? This doesn't allow, e.g., DImode subregs of TImode values
on 32-bit targets. We would need to record the way the
pseudo-register was used, and only decompose if all the uses
were the same number and size of pieces. Hopefully this
doesn't happen much. */
if (outer_words == 1 && inner_words > 1)
{
bitmap_set_bit (decomposable_context, regno);
return -1;
}
/* If this is a cast from one mode to another, where the modes
have the same size, and they are not tieable, then mark this
register as non-decomposable. If we decompose it we are
likely to mess up whatever the backend is trying to do. */
if (outer_words > 1
&& outer_size == inner_size
&& !MODES_TIEABLE_P (GET_MODE (x), GET_MODE (inner)))
{
bitmap_set_bit (non_decomposable_context, regno);
return -1;
}
}
else if (REG_P (x))
{
unsigned int regno;
/* We will see an outer SUBREG before we see the inner REG, so
when we see a plain REG here it means a direct reference to
the register.
If this is not a simple copy from one location to another,
then we can not decompose this register. If this is a simple
copy from one pseudo-register to another, and the mode is right
then we mark the register as decomposable.
Otherwise we don't say anything about this register --
it could be decomposed, but whether that would be
profitable depends upon how it is used elsewhere.
We only set bits in the bitmap for multi-word
pseudo-registers, since those are the only ones we care about
and it keeps the size of the bitmaps down. */
regno = REGNO (x);
if (!HARD_REGISTER_NUM_P (regno)
&& GET_MODE_SIZE (GET_MODE (x)) > UNITS_PER_WORD)
{
switch (*pcmi)
{
case NOT_SIMPLE_MOVE:
bitmap_set_bit (non_decomposable_context, regno);
break;
case SIMPLE_PSEUDO_REG_MOVE:
if (MODES_TIEABLE_P (GET_MODE (x), word_mode))
bitmap_set_bit (decomposable_context, regno);
break;
case SIMPLE_MOVE:
break;
default:
gcc_unreachable ();
}
}
}
else if (MEM_P (x))
{
enum classify_move_insn cmi_mem = NOT_SIMPLE_MOVE;
/* Any registers used in a MEM do not participate in a
SIMPLE_MOVE or SIMPLE_PSEUDO_REG_MOVE. Do our own recursion
here, and return -1 to block the parent's recursion. */
for_each_rtx (&XEXP (x, 0), find_decomposable_subregs, &cmi_mem);
return -1;
}
return 0;
}
/* Decompose REGNO into word-sized components. We smash the REG node
in place. This ensures that (1) something goes wrong quickly if we
fail to make some replacement, and (2) the debug information inside
the symbol table is automatically kept up to date. */
static void
decompose_register (unsigned int regno)
{
rtx reg;
unsigned int words, i;
rtvec v;
reg = regno_reg_rtx[regno];
regno_reg_rtx[regno] = NULL_RTX;
words = GET_MODE_SIZE (GET_MODE (reg));
words = (words + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
v = rtvec_alloc (words);
for (i = 0; i < words; ++i)
RTVEC_ELT (v, i) = gen_reg_rtx_offset (reg, word_mode, i * UNITS_PER_WORD);
PUT_CODE (reg, CONCATN);
XVEC (reg, 0) = v;
if (dump_file)
{
fprintf (dump_file, "; Splitting reg %u ->", regno);
for (i = 0; i < words; ++i)
fprintf (dump_file, " %u", REGNO (XVECEXP (reg, 0, i)));
fputc ('\n', dump_file);
}
}
/* Get a SUBREG of a CONCATN. */
static rtx
simplify_subreg_concatn (enum machine_mode outermode, rtx op,
unsigned int byte)
{
unsigned int inner_size;
enum machine_mode innermode;
rtx part;
unsigned int final_offset;
gcc_assert (GET_CODE (op) == CONCATN);
gcc_assert (byte % GET_MODE_SIZE (outermode) == 0);
innermode = GET_MODE (op);
gcc_assert (byte < GET_MODE_SIZE (innermode));
gcc_assert (GET_MODE_SIZE (outermode) <= GET_MODE_SIZE (innermode));
inner_size = GET_MODE_SIZE (innermode) / XVECLEN (op, 0);
part = XVECEXP (op, 0, byte / inner_size);
final_offset = byte % inner_size;
if (final_offset + GET_MODE_SIZE (outermode) > inner_size)
return NULL_RTX;
return simplify_gen_subreg (outermode, part, GET_MODE (part), final_offset);
}
/* Wrapper around simplify_gen_subreg which handles CONCATN. */
static rtx
simplify_gen_subreg_concatn (enum machine_mode outermode, rtx op,
enum machine_mode innermode, unsigned int byte)
{
rtx ret;
/* We have to handle generating a SUBREG of a SUBREG of a CONCATN.
If OP is a SUBREG of a CONCATN, then it must be a simple mode
change with the same size and offset 0, or it must extract a
part. We shouldn't see anything else here. */
if (GET_CODE (op) == SUBREG && GET_CODE (SUBREG_REG (op)) == CONCATN)
{
rtx op2;
if ((GET_MODE_SIZE (GET_MODE (op))
== GET_MODE_SIZE (GET_MODE (SUBREG_REG (op))))
&& SUBREG_BYTE (op) == 0)
return simplify_gen_subreg_concatn (outermode, SUBREG_REG (op),
GET_MODE (SUBREG_REG (op)), byte);
op2 = simplify_subreg_concatn (GET_MODE (op), SUBREG_REG (op),
SUBREG_BYTE (op));
if (op2 == NULL_RTX)
{
/* We don't handle paradoxical subregs here. */
gcc_assert (GET_MODE_SIZE (outermode)
<= GET_MODE_SIZE (GET_MODE (op)));
gcc_assert (GET_MODE_SIZE (GET_MODE (op))
<= GET_MODE_SIZE (GET_MODE (SUBREG_REG (op))));
op2 = simplify_subreg_concatn (outermode, SUBREG_REG (op),
byte + SUBREG_BYTE (op));
gcc_assert (op2 != NULL_RTX);
return op2;
}
op = op2;
gcc_assert (op != NULL_RTX);
gcc_assert (innermode == GET_MODE (op));
}
if (GET_CODE (op) == CONCATN)
return simplify_subreg_concatn (outermode, op, byte);
ret = simplify_gen_subreg (outermode, op, innermode, byte);
/* If we see an insn like (set (reg:DI) (subreg:DI (reg:SI) 0)) then
resolve_simple_move will ask for the high part of the paradoxical
subreg, which does not have a value. Just return a zero. */
if (ret == NULL_RTX
&& GET_CODE (op) == SUBREG
&& SUBREG_BYTE (op) == 0
&& (GET_MODE_SIZE (innermode)
> GET_MODE_SIZE (GET_MODE (SUBREG_REG (op)))))
return CONST0_RTX (outermode);
gcc_assert (ret != NULL_RTX);
return ret;
}
/* Return whether we should resolve X into the registers into which it
was decomposed. */
static bool
resolve_reg_p (rtx x)
{
return GET_CODE (x) == CONCATN;
}
/* Return whether X is a SUBREG of a register which we need to
resolve. */
static bool
resolve_subreg_p (rtx x)
{
if (GET_CODE (x) != SUBREG)
return false;
return resolve_reg_p (SUBREG_REG (x));
}
/* This is called via for_each_rtx. Look for SUBREGs which need to be
decomposed. */
static int
resolve_subreg_use (rtx *px, void *data)
{
rtx insn = (rtx) data;
rtx x = *px;
if (x == NULL_RTX)
return 0;
if (resolve_subreg_p (x))
{
x = simplify_subreg_concatn (GET_MODE (x), SUBREG_REG (x),
SUBREG_BYTE (x));
/* It is possible for a note to contain a reference which we can
decompose. In this case, return 1 to the caller to indicate
that the note must be removed. */
if (!x)
{
gcc_assert (!insn);
return 1;
}
validate_change (insn, px, x, 1);
return -1;
}
if (resolve_reg_p (x))
{
/* Return 1 to the caller to indicate that we found a direct
reference to a register which is being decomposed. This can
happen inside notes, multiword shift or zero-extend
instructions. */
return 1;
}
return 0;
}
/* We are deleting INSN. Move any EH_REGION notes to INSNS. */
static void
move_eh_region_note (rtx insn, rtx insns)
{
rtx note, p;
note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
if (note == NULL_RTX)
return;
gcc_assert (CALL_P (insn)
|| (flag_non_call_exceptions && may_trap_p (PATTERN (insn))));
for (p = insns; p != NULL_RTX; p = NEXT_INSN (p))
{
if (CALL_P (p)
|| (flag_non_call_exceptions
&& INSN_P (p)
&& may_trap_p (PATTERN (p))))
add_reg_note (p, REG_EH_REGION, XEXP (note, 0));
}
}
/* Resolve any decomposed registers which appear in register notes on
INSN. */
static void
resolve_reg_notes (rtx insn)
{
rtx *pnote, note;
note = find_reg_equal_equiv_note (insn);
if (note)
{
int old_count = num_validated_changes ();
if (for_each_rtx (&XEXP (note, 0), resolve_subreg_use, NULL))
remove_note (insn, note);
else
if (old_count != num_validated_changes ())
df_notes_rescan (insn);
}
pnote = ®_NOTES (insn);
while (*pnote != NULL_RTX)
{
bool del = false;
note = *pnote;
switch (REG_NOTE_KIND (note))
{
case REG_DEAD:
case REG_UNUSED:
if (resolve_reg_p (XEXP (note, 0)))
del = true;
break;
default:
break;
}
if (del)
*pnote = XEXP (note, 1);
else
pnote = &XEXP (note, 1);
}
}
/* Return whether X can be decomposed into subwords. */
static bool
can_decompose_p (rtx x)
{
if (REG_P (x))
{
unsigned int regno = REGNO (x);
if (HARD_REGISTER_NUM_P (regno))
return (validate_subreg (word_mode, GET_MODE (x), x, UNITS_PER_WORD)
&& HARD_REGNO_MODE_OK (regno, word_mode));
else
return !bitmap_bit_p (non_decomposable_context, regno);
}
return true;
}
/* Decompose the registers used in a simple move SET within INSN. If
we don't change anything, return INSN, otherwise return the start
of the sequence of moves. */
static rtx
resolve_simple_move (rtx set, rtx insn)
{
rtx src, dest, real_dest, insns;
enum machine_mode orig_mode, dest_mode;
unsigned int words;
bool pushing;
src = SET_SRC (set);
dest = SET_DEST (set);
orig_mode = GET_MODE (dest);
words = (GET_MODE_SIZE (orig_mode) + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
if (words <= 1)
return insn;
start_sequence ();
/* We have to handle copying from a SUBREG of a decomposed reg where
the SUBREG is larger than word size. Rather than assume that we
can take a word_mode SUBREG of the destination, we copy to a new
register and then copy that to the destination. */
real_dest = NULL_RTX;
if (GET_CODE (src) == SUBREG
&& resolve_reg_p (SUBREG_REG (src))
&& (SUBREG_BYTE (src) != 0
|| (GET_MODE_SIZE (orig_mode)
!= GET_MODE_SIZE (GET_MODE (SUBREG_REG (src))))))
{
real_dest = dest;
dest = gen_reg_rtx (orig_mode);
if (REG_P (real_dest))
REG_ATTRS (dest) = REG_ATTRS (real_dest);
}
/* Similarly if we are copying to a SUBREG of a decomposed reg where
the SUBREG is larger than word size. */
if (GET_CODE (dest) == SUBREG
&& resolve_reg_p (SUBREG_REG (dest))
&& (SUBREG_BYTE (dest) != 0
|| (GET_MODE_SIZE (orig_mode)
!= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))))))
{
rtx reg, minsn, smove;
reg = gen_reg_rtx (orig_mode);
minsn = emit_move_insn (reg, src);
smove = single_set (minsn);
gcc_assert (smove != NULL_RTX);
resolve_simple_move (smove, minsn);
src = reg;
}
/* If we didn't have any big SUBREGS of decomposed registers, and
neither side of the move is a register we are decomposing, then
we don't have to do anything here. */
if (src == SET_SRC (set)
&& dest == SET_DEST (set)
&& !resolve_reg_p (src)
&& !resolve_subreg_p (src)
&& !resolve_reg_p (dest)
&& !resolve_subreg_p (dest))
{
end_sequence ();
return insn;
}
/* It's possible for the code to use a subreg of a decomposed
register while forming an address. We need to handle that before
passing the address to emit_move_insn. We pass NULL_RTX as the
insn parameter to resolve_subreg_use because we can not validate
the insn yet. */
if (MEM_P (src) || MEM_P (dest))
{
int acg;
if (MEM_P (src))
for_each_rtx (&XEXP (src, 0), resolve_subreg_use, NULL_RTX);
if (MEM_P (dest))
for_each_rtx (&XEXP (dest, 0), resolve_subreg_use, NULL_RTX);
acg = apply_change_group ();
gcc_assert (acg);
}
/* If SRC is a register which we can't decompose, or has side
effects, we need to move via a temporary register. */
if (!can_decompose_p (src)
|| side_effects_p (src)
|| GET_CODE (src) == ASM_OPERANDS)
{
rtx reg;
reg = gen_reg_rtx (orig_mode);
emit_move_insn (reg, src);
src = reg;
}
/* If DEST is a register which we can't decompose, or has side
effects, we need to first move to a temporary register. We
handle the common case of pushing an operand directly. We also
go through a temporary register if it holds a floating point
value. This gives us better code on systems which can't move
data easily between integer and floating point registers. */
dest_mode = orig_mode;
pushing = push_operand (dest, dest_mode);
if (!can_decompose_p (dest)
|| (side_effects_p (dest) && !pushing)
|| (!SCALAR_INT_MODE_P (dest_mode)
&& !resolve_reg_p (dest)
&& !resolve_subreg_p (dest)))
{
if (real_dest == NULL_RTX)
real_dest = dest;
if (!SCALAR_INT_MODE_P (dest_mode))
{
dest_mode = mode_for_size (GET_MODE_SIZE (dest_mode) * BITS_PER_UNIT,
MODE_INT, 0);
gcc_assert (dest_mode != BLKmode);
}
dest = gen_reg_rtx (dest_mode);
if (REG_P (real_dest))
REG_ATTRS (dest) = REG_ATTRS (real_dest);
}
if (pushing)
{
unsigned int i, j, jinc;
gcc_assert (GET_MODE_SIZE (orig_mode) % UNITS_PER_WORD == 0);
gcc_assert (GET_CODE (XEXP (dest, 0)) != PRE_MODIFY);
gcc_assert (GET_CODE (XEXP (dest, 0)) != POST_MODIFY);
if (WORDS_BIG_ENDIAN == STACK_GROWS_DOWNWARD)
{
j = 0;
jinc = 1;
}
else
{
j = words - 1;
jinc = -1;
}
for (i = 0; i < words; ++i, j += jinc)
{
rtx temp;
temp = copy_rtx (XEXP (dest, 0));
temp = adjust_automodify_address_nv (dest, word_mode, temp,
j * UNITS_PER_WORD);
emit_move_insn (temp,
simplify_gen_subreg_concatn (word_mode, src,
orig_mode,
j * UNITS_PER_WORD));
}
}
else
{
unsigned int i;
if (REG_P (dest) && !HARD_REGISTER_NUM_P (REGNO (dest)))
emit_clobber (dest);
for (i = 0; i < words; ++i)
emit_move_insn (simplify_gen_subreg_concatn (word_mode, dest,
dest_mode,
i * UNITS_PER_WORD),
simplify_gen_subreg_concatn (word_mode, src,
orig_mode,
i * UNITS_PER_WORD));
}
if (real_dest != NULL_RTX)
{
rtx mdest, minsn, smove;
if (dest_mode == orig_mode)
mdest = dest;
else
mdest = simplify_gen_subreg (orig_mode, dest, GET_MODE (dest), 0);
minsn = emit_move_insn (real_dest, mdest);
smove = single_set (minsn);
gcc_assert (smove != NULL_RTX);
resolve_simple_move (smove, minsn);
}
insns = get_insns ();
end_sequence ();
move_eh_region_note (insn, insns);
emit_insn_before (insns, insn);
delete_insn (insn);
return insns;
}
/* Change a CLOBBER of a decomposed register into a CLOBBER of the
component registers. Return whether we changed something. */
static bool
resolve_clobber (rtx pat, rtx insn)
{
rtx reg;
enum machine_mode orig_mode;
unsigned int words, i;
int ret;
reg = XEXP (pat, 0);
if (!resolve_reg_p (reg) && !resolve_subreg_p (reg))
return false;
orig_mode = GET_MODE (reg);
words = GET_MODE_SIZE (orig_mode);
words = (words + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
ret = validate_change (NULL_RTX, &XEXP (pat, 0),
simplify_gen_subreg_concatn (word_mode, reg,
orig_mode, 0),
0);
df_insn_rescan (insn);
gcc_assert (ret != 0);
for (i = words - 1; i > 0; --i)
{
rtx x;
x = simplify_gen_subreg_concatn (word_mode, reg, orig_mode,
i * UNITS_PER_WORD);
x = gen_rtx_CLOBBER (VOIDmode, x);
emit_insn_after (x, insn);
}
resolve_reg_notes (insn);
return true;
}
/* A USE of a decomposed register is no longer meaningful. Return
whether we changed something. */
static bool
resolve_use (rtx pat, rtx insn)
{
if (resolve_reg_p (XEXP (pat, 0)) || resolve_subreg_p (XEXP (pat, 0)))
{
delete_insn (insn);
return true;
}
resolve_reg_notes (insn);
return false;
}
/* Checks if INSN is a decomposable multiword-shift or zero-extend and
sets the decomposable_context bitmap accordingly. A non-zero value
is returned if a decomposable insn has been found. */
static int
find_decomposable_shift_zext (rtx insn)
{
rtx set;
rtx op;
rtx op_operand;
set = single_set (insn);
if (!set)
return 0;
op = SET_SRC (set);
if (GET_CODE (op) != ASHIFT
&& GET_CODE (op) != LSHIFTRT
&& GET_CODE (op) != ZERO_EXTEND)
return 0;
op_operand = XEXP (op, 0);
if (!REG_P (SET_DEST (set)) || !REG_P (op_operand)
|| HARD_REGISTER_NUM_P (REGNO (SET_DEST (set)))
|| HARD_REGISTER_NUM_P (REGNO (op_operand))
|| !SCALAR_INT_MODE_P (GET_MODE (op)))
return 0;
if (GET_CODE (op) == ZERO_EXTEND)
{
if (GET_MODE (op_operand) != word_mode
|| GET_MODE_BITSIZE (GET_MODE (op)) != 2 * BITS_PER_WORD)
return 0;
}
else /* left or right shift */
{
if (GET_CODE (XEXP (op, 1)) != CONST_INT
|| INTVAL (XEXP (op, 1)) < BITS_PER_WORD
|| GET_MODE_BITSIZE (GET_MODE (op_operand)) != 2 * BITS_PER_WORD)
return 0;
}
bitmap_set_bit (decomposable_context, REGNO (SET_DEST (set)));
if (GET_CODE (op) != ZERO_EXTEND)
bitmap_set_bit (decomposable_context, REGNO (op_operand));
return 1;
}
/* Decompose a more than word wide shift (in INSN) of a multiword
pseudo or a multiword zero-extend of a wordmode pseudo into a move
and 'set to zero' insn. Return a pointer to the new insn when a
replacement was done. */
static rtx
resolve_shift_zext (rtx insn)
{
rtx set;
rtx op;
rtx op_operand;
rtx insns;
rtx src_reg, dest_reg, dest_zero;
int src_reg_num, dest_reg_num, offset1, offset2, src_offset;
set = single_set (insn);
if (!set)
return NULL_RTX;
op = SET_SRC (set);
if (GET_CODE (op) != ASHIFT
&& GET_CODE (op) != LSHIFTRT
&& GET_CODE (op) != ZERO_EXTEND)
return NULL_RTX;
op_operand = XEXP (op, 0);
if (!resolve_reg_p (SET_DEST (set)) && !resolve_reg_p (op_operand))
return NULL_RTX;
/* src_reg_num is the number of the word mode register which we
are operating on. For a left shift and a zero_extend on little
endian machines this is register 0. */
src_reg_num = GET_CODE (op) == LSHIFTRT ? 1 : 0;
if (WORDS_BIG_ENDIAN
&& GET_MODE_SIZE (GET_MODE (op_operand)) > UNITS_PER_WORD)
src_reg_num = 1 - src_reg_num;
if (GET_CODE (op) == ZERO_EXTEND)
dest_reg_num = WORDS_BIG_ENDIAN ? 1 : 0;
else
dest_reg_num = 1 - src_reg_num;
offset1 = UNITS_PER_WORD * dest_reg_num;
offset2 = UNITS_PER_WORD * (1 - dest_reg_num);
src_offset = UNITS_PER_WORD * src_reg_num;
if (WORDS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
{
offset1 += UNITS_PER_WORD - 1;
offset2 += UNITS_PER_WORD - 1;
src_offset += UNITS_PER_WORD - 1;
}
start_sequence ();
dest_reg = simplify_gen_subreg_concatn (word_mode, SET_DEST (set),
GET_MODE (SET_DEST (set)),
offset1);
dest_zero = simplify_gen_subreg_concatn (word_mode, SET_DEST (set),
GET_MODE (SET_DEST (set)),