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Further improvements to constant shifts for the H8

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gcc/
	* config/h8300/h8300.c (shift_alg_hi): Improve arithmetic shift right
	by 15 bits for H8/300H and H8/S.  Improve logical shifts by 12
	bits for H8/S.
	(shift_alg_si): Improve arithmetic right shift by 28-30 bits for
	H8/300H.  Improve arithmetic shift right by 15 bits for H8/S.
	Improve logical shifts by 27 bits for H8/S.
	(get_shift_alg): Corresponding changes.
	(h8300_option_override): Revert to loops for -Os when profitable.
This commit is contained in:
Jeff Law 2021-08-20 11:19:05 -04:00
parent 29b2fd371f
commit 5f80c6270d
1 changed files with 32 additions and 6 deletions
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38
gcc/config/h8300/h8300.c
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@ -213,9 +213,9 @@ static enum shift_alg shift_alg_hi[2][3][16] = {
/* 0 1 2 3 4 5 6 7 */
/* 8 9 10 11 12 13 14 15 */
{ INL, INL, INL, INL, INL, INL, INL, INL,
SPC, SPC, SPC, SPC, SPC, ROT, ROT, ROT }, /* SHIFT_ASHIFT */
SPC, SPC, SPC, SPC, ROT, ROT, ROT, ROT }, /* SHIFT_ASHIFT */
{ INL, INL, INL, INL, INL, INL, INL, INL,
SPC, SPC, SPC, SPC, SPC, ROT, ROT, ROT }, /* SHIFT_LSHIFTRT */
SPC, SPC, SPC, SPC, ROT, ROT, ROT, ROT }, /* SHIFT_LSHIFTRT */
{ INL, INL, INL, INL, INL, INL, INL, INL,
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC }, /* SHIFT_ASHIFTRT */
}
@ -237,9 +237,9 @@ static enum shift_alg shift_alg_si[2][3][32] = {
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC,
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC }, /* SHIFT_LSHIFTRT */
{ INL, INL, INL, INL, INL, INL, INL, LOP,
SPC, LOP, LOP, LOP, LOP, LOP, LOP, LOP,
SPC, LOP, LOP, LOP, LOP, LOP, LOP, SPC,
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC,
SPC, SPC, SPC, SPC, LOP, LOP, LOP, SPC }, /* SHIFT_ASHIFTRT */
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC }, /* SHIFT_ASHIFTRT */
},
{
/* TARGET_H8300S */
@ -256,7 +256,7 @@ static enum shift_alg shift_alg_si[2][3][32] = {
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC,
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC }, /* SHIFT_LSHIFTRT */
{ INL, INL, INL, INL, INL, INL, INL, INL,
INL, INL, INL, INL, INL, INL, INL, LOP,
INL, INL, INL, INL, INL, INL, INL, SPC,
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC,
SPC, SPC, SPC, SPC, SPC, SPC, SPC, SPC }, /* SHIFT_ASHIFTRT */
}
@ -372,6 +372,9 @@ h8300_option_override (void)
shift_alg_si[H8_300H][SHIFT_ASHIFTRT][25] = SHIFT_LOOP;
shift_alg_si[H8_300H][SHIFT_ASHIFTRT][26] = SHIFT_LOOP;
shift_alg_si[H8_300H][SHIFT_ASHIFTRT][27] = SHIFT_LOOP;
shift_alg_si[H8_300H][SHIFT_ASHIFTRT][28] = SHIFT_LOOP;
shift_alg_si[H8_300H][SHIFT_ASHIFTRT][29] = SHIFT_LOOP;
shift_alg_si[H8_300H][SHIFT_ASHIFTRT][30] = SHIFT_LOOP;
/* H8S */
shift_alg_hi[H8_S][SHIFT_ASHIFTRT][14] = SHIFT_LOOP;
@ -3830,6 +3833,10 @@ get_shift_alg (enum shift_type shift_type, enum shift_mode shift_mode,
}
else if (count == 15)
{
/* The basic idea here is to use the shift-by-16 idiom to make things
small and efficient. Of course, that loses one bit that we need,
so we stuff the bit into C, shift by 16, then rotate the bit
back in. */
switch (shift_type)
{
case SHIFT_ASHIFT:
@ -3841,7 +3848,9 @@ get_shift_alg (enum shift_type shift_type, enum shift_mode shift_mode,
info->cc_special = OLD_CC_SET_ZNV;
goto end;
case SHIFT_ASHIFTRT:
gcc_unreachable ();
info->special = "shll.w\t%f0\n\tmov.w\t%e0,%f0\n\texts.l\t%S0\n\trotxl.l\t%S0";
info->cc_special = OLD_CC_SET_ZNV;
goto end;
}
}
else if (count >= 16 && count <= 23)
@ -3863,6 +3872,23 @@ get_shift_alg (enum shift_type shift_type, enum shift_mode shift_mode,
goto end;
}
}
else if (TARGET_H8300S && count == 27)
{
switch (shift_type)
{
case SHIFT_ASHIFT:
info->special = "sub.w\t%e0,%e0\n\trotr.l\t#2,%S0\n\trotr.l\t#2,%S0\n\trotr.l\t%S0\n\tsub.w\t%f0,%f0";
goto end;
case SHIFT_LSHIFTRT:
info->special = "sub.w\t%f0,%f0\n\trotl.l\t#2,%S0\n\trotl.l\t#2,%S0\n\trotl.l\t%S0\n\textu.l\t%S0";
goto end;
case SHIFT_ASHIFTRT:
info->remainder = count - 24;
info->special = "mov.w\t%e0,%f0\n\tmov.b\t%t0,%s0\n\texts.w\t%f0\n\texts.l\t%S0";
info->cc_special = OLD_CC_SET_ZNV;
goto end;
}
}
else if (count >= 24 && count <= 27)
{
info->remainder = count - 24;