public inbox for glibc-cvs@sourceware.org
help / color / mirror / Atom feed
* [glibc/release/2.33/master] AArch64: Optimize memchr
@ 2024-04-10 16:37 Wilco Dijkstra
0 siblings, 0 replies; only message in thread
From: Wilco Dijkstra @ 2024-04-10 16:37 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=50ebfdfe8a9e6f0695941d023277d4dd8b95be9a
commit 50ebfdfe8a9e6f0695941d023277d4dd8b95be9a
Author: Wilco Dijkstra <wilco.dijkstra@arm.com>
Date: Wed Jan 11 13:50:59 2023 +0000
AArch64: Optimize memchr
Optimize the main loop - large strings are 40% faster on modern CPUs.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
(cherry picked from commit ce758d4f063820c2bc743e12797d7454c66be718)
Diff:
---
sysdeps/aarch64/memchr.S | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/sysdeps/aarch64/memchr.S b/sysdeps/aarch64/memchr.S
index d6c588dba7..76f801b6c0 100644
--- a/sysdeps/aarch64/memchr.S
+++ b/sysdeps/aarch64/memchr.S
@@ -30,7 +30,6 @@
# define MEMCHR __memchr
#endif
-/* Arguments and results. */
#define srcin x0
#define chrin w1
#define cntin x2
@@ -73,42 +72,44 @@ ENTRY (MEMCHR)
rbit synd, synd
clz synd, synd
- add result, srcin, synd, lsr 2
cmp cntin, synd, lsr 2
+ add result, srcin, synd, lsr 2
csel result, result, xzr, hi
ret
+ .p2align 3
L(start_loop):
sub tmp, src, srcin
- add tmp, tmp, 16
+ add tmp, tmp, 17
subs cntrem, cntin, tmp
- b.ls L(nomatch)
+ b.lo L(nomatch)
/* Make sure that it won't overread by a 16-byte chunk */
- add tmp, cntrem, 15
- tbnz tmp, 4, L(loop32_2)
-
+ tbz cntrem, 4, L(loop32_2)
+ sub src, src, 16
.p2align 4
L(loop32):
- ldr qdata, [src, 16]!
+ ldr qdata, [src, 32]!
cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
umaxp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
fmov synd, dend
cbnz synd, L(end)
L(loop32_2):
- ldr qdata, [src, 16]!
- subs cntrem, cntrem, 32
+ ldr qdata, [src, 16]
cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
- b.ls L(end)
+ subs cntrem, cntrem, 32
+ b.lo L(end_2)
umaxp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
fmov synd, dend
cbz synd, L(loop32)
+L(end_2):
+ add src, src, 16
L(end):
shrn vend.8b, vhas_chr.8h, 4 /* 128->64 */
+ sub cntrem, src, srcin
fmov synd, dend
- add tmp, srcin, cntin
- sub cntrem, tmp, src
+ sub cntrem, cntin, cntrem
#ifndef __AARCH64EB__
rbit synd, synd
#endif
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2024-04-10 16:37 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-04-10 16:37 [glibc/release/2.33/master] AArch64: Optimize memchr Wilco Dijkstra
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).