procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fix emit_group_store regression on big-endian

Browse source 
The recent optimization implemented for complex modes contains an oversight
for big-endian platforms: it uses a lowpart SUBREG when the integer modes
have different sizes, but this does not match the semantics of the PARALLELs
which have a bundled byte offset; this offset is always zero in the code
path and the lowpart is not at offset zero on big-endian platforms.

gcc/
	* expr.cc (emit_group_stote): Fix handling of modes of different
	sizes for big-endian targets in latest change and add commentary.
This commit is contained in:
Eric Botcazou 2022-10-12 09:27:19 +02:00
parent fc748d47e9
commit c853d655ab
1 changed files with 32 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

44
gcc/expr.cc
View file

@ -2813,50 +2813,69 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED,
else
adj_bytelen = bytelen;
/* Deal with destination CONCATs by either storing into one of the parts
or doing a copy after storing into a register or stack temporary. */
if (GET_CODE (dst) == CONCAT)
{
if (known_le (bytepos + adj_bytelen,
GET_MODE_SIZE (GET_MODE (XEXP (dst, 0)))))
dest = XEXP (dst, 0);
else if (known_ge (bytepos, GET_MODE_SIZE (GET_MODE (XEXP (dst, 0)))))
{
bytepos -= GET_MODE_SIZE (GET_MODE (XEXP (dst, 0)));
dest = XEXP (dst, 1);
}
else
{
machine_mode dest_mode = GET_MODE (dest);
machine_mode tmp_mode = GET_MODE (tmps[i]);
scalar_int_mode imode;
scalar_int_mode dest_imode;
gcc_assert (known_eq (bytepos, 0) && XVECLEN (src, 0));
if (finish == 1
/* If the source is a single scalar integer register, and the
destination has a complex mode for which a same-sized integer
mode exists, then we can take the left-justified part of the
source in the complex mode. */
if (finish == start + 1
&& REG_P (tmps[i])
&& COMPLEX_MODE_P (dest_mode)
&& SCALAR_INT_MODE_P (tmp_mode)
&& int_mode_for_mode (dest_mode).exists (&imode))
&& COMPLEX_MODE_P (dest_mode)
&& int_mode_for_mode (dest_mode).exists (&dest_imode))
{
if (tmp_mode != imode)
const scalar_int_mode tmp_imode
= as_a <scalar_int_mode> (tmp_mode);
if (GET_MODE_BITSIZE (dest_imode)
< GET_MODE_BITSIZE (tmp_imode))
{
rtx tmp = gen_reg_rtx (imode);
emit_move_insn (tmp, gen_lowpart (imode, tmps[i]));
dst = gen_lowpart (dest_mode, tmp);
dest = gen_reg_rtx (dest_imode);
if (BYTES_BIG_ENDIAN)
tmps[i] = expand_shift (RSHIFT_EXPR, tmp_mode, tmps[i],
GET_MODE_BITSIZE (tmp_imode)
- GET_MODE_BITSIZE (dest_imode),
NULL_RTX, 1);
emit_move_insn (dest, gen_lowpart (dest_imode, tmps[i]));
dst = gen_lowpart (dest_mode, dest);
}
else
dst = gen_lowpart (dest_mode, tmps[i]);
}
/* Otherwise spill the source onto the stack using the more
aligned of the two modes. */
else if (GET_MODE_ALIGNMENT (dest_mode)
>= GET_MODE_ALIGNMENT (tmp_mode))
>= GET_MODE_ALIGNMENT (tmp_mode))
{
dest = assign_stack_temp (dest_mode,
GET_MODE_SIZE (dest_mode));
emit_move_insn (adjust_address (dest,
tmp_mode,
bytepos),
emit_move_insn (adjust_address (dest, tmp_mode, bytepos),
tmps[i]);
dst = dest;
}
else
{
dest = assign_stack_temp (tmp_mode,
@ -2864,6 +2883,7 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED,
emit_move_insn (dest, tmps[i]);
dst = adjust_address (dest, dest_mode, bytepos);
}
break;
}
}