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[MIPS] Optimize flow of csum_partial

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Delete dead codes at end of the function and move small_csumcopy
there.  This makes some labels (maybe_end_cruft, small_memcpy,
end_bytes, out) needless and eliminates some branches.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Atsushi Nemoto 2006-12-08 01:04:45 +09:00 committed by Ralf Baechle
parent 52ffe760ea
commit 773ff78838
1 changed files with 54 additions and 75 deletions
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129
arch/mips/lib/csum_partial.S
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@ -65,64 +65,6 @@
.text .text
.set noreorder .set noreorder
/* unknown src alignment and < 8 bytes to go */
small_csumcpy:
move a1, t2
andi t0, a1, 4
beqz t0, 1f
andi t0, a1, 2
/* Still a full word to go */
ulw t1, (src)
PTR_ADDIU src, 4
ADDC(sum, t1)
1: move t1, zero
beqz t0, 1f
andi t0, a1, 1
/* Still a halfword to go */
ulhu t1, (src)
PTR_ADDIU src, 2
1: beqz t0, 1f
sll t1, t1, 16
lbu t2, (src)
nop
#ifdef __MIPSEB__
sll t2, t2, 8
#endif
or t1, t2
1: ADDC(sum, t1)
/* fold checksum */
sll v1, sum, 16
addu sum, v1
sltu v1, sum, v1
srl sum, sum, 16
addu sum, v1
/* odd buffer alignment? */
beqz t7, 1f
nop
sll v1, sum, 8
srl sum, sum, 8
or sum, v1
andi sum, 0xffff
1:
.set reorder
/* Add the passed partial csum. */
ADDC(sum, a2)
jr ra
.set noreorder
/* ------------------------------------------------------------------------- */
.align 5 .align 5
LEAF(csum_partial) LEAF(csum_partial)
move sum, zero move sum, zero
@ -132,8 +74,7 @@ LEAF(csum_partial)
bnez t8, small_csumcpy /* < 8 bytes to copy */ bnez t8, small_csumcpy /* < 8 bytes to copy */
move t2, a1 move t2, a1
beqz a1, out andi t7, src, 0x1 /* odd buffer? */
andi t7, src, 0x1 /* odd buffer? */
hword_align: hword_align:
beqz t7, word_align beqz t7, word_align
@ -232,8 +173,9 @@ move_32bytes:
PTR_ADDU src, src, 0x20 PTR_ADDU src, src, 0x20
do_end_words: do_end_words:
beqz t8, maybe_end_cruft beqz t8, small_csumcpy
LONG_SRL t8, t8, 0x2 andi t2, a1, 0x3
LONG_SRL t8, t8, 0x2
end_words: end_words:
lw t0, (src) lw t0, (src)
@ -242,21 +184,58 @@ end_words:
bnez t8, end_words bnez t8, end_words
PTR_ADDU src, src, 0x4 PTR_ADDU src, src, 0x4
maybe_end_cruft: /* unknown src alignment and < 8 bytes to go */
andi t2, a1, 0x3 small_csumcpy:
move a1, t2
small_memcpy: andi t0, a1, 4
j small_csumcpy; move a1, t2 /* XXX ??? */ beqz t0, 1f
beqz t2, out andi t0, a1, 2
move a1, t2
end_bytes: /* Still a full word to go */
lb t0, (src) ulw t1, (src)
LONG_SUBU a1, a1, 0x1 PTR_ADDIU src, 4
bnez a2, end_bytes ADDC(sum, t1)
PTR_ADDU src, src, 0x1
out: 1: move t1, zero
beqz t0, 1f
andi t0, a1, 1
/* Still a halfword to go */
ulhu t1, (src)
PTR_ADDIU src, 2
1: beqz t0, 1f
sll t1, t1, 16
lbu t2, (src)
nop
#ifdef __MIPSEB__
sll t2, t2, 8
#endif
or t1, t2
1: ADDC(sum, t1)
/* fold checksum */
sll v1, sum, 16
addu sum, v1
sltu v1, sum, v1
srl sum, sum, 16
addu sum, v1
/* odd buffer alignment? */
beqz t7, 1f
nop
sll v1, sum, 8
srl sum, sum, 8
or sum, v1
andi sum, 0xffff
1:
.set reorder
/* Add the passed partial csum. */
ADDC(sum, a2)
jr ra jr ra
move v0, sum .set noreorder
END(csum_partial) END(csum_partial)