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re PR target/21329 (optimize i386 block copy)

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2005-05-06  Denis Vlasenko  <vda@port.imtp.ilyichevsk.odessa.ua>
	    Jakub Jelinek  <jakub@redhat.com>

	PR target/21329
	* config/i386/i386.c (ix86_expand_movmem): Don't use rep; movsb
	for -Os if (movsl;)*(movsw;)?(movsb;)? sequence is shorter.
	Don't use rep; movs{l,q} if the repetition count is really small,
	instead use a sequence of movs{l,q} instructions.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r99330
This commit is contained in:
Denis Vlasenko 2005-05-06 19:31:13 +00:00 committed by Jakub Jelinek
parent 2b41c04016
commit 95935e2db5
2 changed files with 50 additions and 13 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2005-05-06 Denis Vlasenko <vda@port.imtp.ilyichevsk.odessa.ua>
Jakub Jelinek <jakub@redhat.com>
PR target/21329
* config/i386/i386.c (ix86_expand_movmem): Don't use rep; movsb
for -Os if (movsl;)*(movsw;)?(movsb;)? sequence is shorter.
Don't use rep; movs{l,q} if the repetition count is really small,
instead use a sequence of movs{l,q} instructions.
2005-05-06 Jeff Law <law@redhat.com>
PR tree-optimization/21380

54
gcc/config/i386/i386.c
View File

@ -11285,9 +11285,20 @@ ix86_expand_movmem (rtx dst, rtx src, rtx count_exp, rtx align_exp)
src = replace_equiv_address_nv (src, srcreg);
/* When optimizing for size emit simple rep ; movsb instruction for
counts not divisible by 4. */
counts not divisible by 4, except when (movsl;)*(movsw;)?(movsb;)?
sequence is shorter than mov{b,l} $count, %{ecx,cl}; rep; movsb.
Sice of (movsl;)*(movsw;)?(movsb;)? sequence is
count / 4 + (count & 3), the other sequence is either 4 or 7 bytes,
but we don't know whether upper 24 (resp. 56) bits of %ecx will be
known to be zero or not. The rep; movsb sequence causes higher
register preasure though, so take that into account. */
if ((!optimize || optimize_size) && (count == 0 || (count & 0x03)))
if ((!optimize || optimize_size)
&& (count == 0
|| ((count & 0x03)
&& (!optimize_size
|| count > 5 * 4
|| (count & 3) + count / 4 > 6))))
{
emit_insn (gen_cld ());
countreg = ix86_zero_extend_to_Pmode (count_exp);
@ -11313,19 +11324,36 @@ ix86_expand_movmem (rtx dst, rtx src, rtx count_exp, rtx align_exp)
emit_insn (gen_cld ());
if (count & ~(size - 1))
{
countreg = copy_to_mode_reg (counter_mode,
GEN_INT ((count >> (size == 4 ? 2 : 3))
& (TARGET_64BIT ? -1 : 0x3fffffff)));
countreg = ix86_zero_extend_to_Pmode (countreg);
if ((TARGET_SINGLE_STRINGOP || optimize_size) && count < 5 * 4)
{
enum machine_mode movs_mode = size == 4 ? SImode : DImode;
destexp = gen_rtx_ASHIFT (Pmode, countreg,
GEN_INT (size == 4 ? 2 : 3));
srcexp = gen_rtx_PLUS (Pmode, destexp, srcreg);
destexp = gen_rtx_PLUS (Pmode, destexp, destreg);
while (offset < (count & ~(size - 1)))
{
srcmem = adjust_automodify_address_nv (src, movs_mode,
srcreg, offset);
dstmem = adjust_automodify_address_nv (dst, movs_mode,
destreg, offset);
emit_insn (gen_strmov (destreg, dstmem, srcreg, srcmem));
offset += size;
}
}
else
{
countreg = GEN_INT ((count >> (size == 4 ? 2 : 3))
& (TARGET_64BIT ? -1 : 0x3fffffff));
countreg = copy_to_mode_reg (counter_mode, countreg);
countreg = ix86_zero_extend_to_Pmode (countreg);
emit_insn (gen_rep_mov (destreg, dst, srcreg, src,
countreg, destexp, srcexp));
offset = count & ~(size - 1);
destexp = gen_rtx_ASHIFT (Pmode, countreg,
GEN_INT (size == 4 ? 2 : 3));
srcexp = gen_rtx_PLUS (Pmode, destexp, srcreg);
destexp = gen_rtx_PLUS (Pmode, destexp, destreg);
emit_insn (gen_rep_mov (destreg, dst, srcreg, src,
countreg, destexp, srcexp));
offset = count & ~(size - 1);
}
}
if (size == 8 && (count & 0x04))
{