diff options
| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2015-09-22 16:34:32 +0200 |
|---|---|---|
| committer | Scott Wood <oss@buserror.net> | 2016-03-04 23:03:45 -0600 |
| commit | f867d556dd8525fe6ff0d22a34249528e590f994 (patch) | |
| tree | 32ebba9cfc1b00d1f394b480d5cfab443382864e /arch/powerpc/lib | |
| parent | 48821a34b1bdc5d89505cb814b3f7c166940f200 (diff) | |
powerpc32: optimise csum_partial() loop
On the 8xx, load latency is 2 cycles and taking branches also takes
2 cycles. So let's unroll the loop.
This patch improves csum_partial() speed by around 10% on both:
* 8xx (single issue processor with parallel execution)
* 83xx (superscalar 6xx processor with dual instruction fetch
and parallel execution)
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>
Diffstat (limited to 'arch/powerpc/lib')
| -rw-r--r-- | arch/powerpc/lib/checksum_32.S | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S index 9c126028ab9c..0d34f47c8a5e 100644 --- a/arch/powerpc/lib/checksum_32.S +++ b/arch/powerpc/lib/checksum_32.S @@ -38,10 +38,24 @@ _GLOBAL(csum_partial) srwi. r6,r4,2 /* # words to do */ adde r5,r5,r0 beq 3f -1: mtctr r6 +1: andi. r6,r6,3 /* Prepare to handle words 4 by 4 */ + beq 21f + mtctr r6 2: lwzu r0,4(r3) adde r5,r5,r0 bdnz 2b +21: srwi. r6,r4,4 /* # blocks of 4 words to do */ + beq 3f + mtctr r6 +22: lwz r0,4(r3) + lwz r6,8(r3) + lwz r7,12(r3) + lwzu r8,16(r3) + adde r5,r5,r0 + adde r5,r5,r6 + adde r5,r5,r7 + adde r5,r5,r8 + bdnz 22b 3: andi. r0,r4,2 beq+ 4f lhz r0,4(r3) |