From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1895) id 74056384188C; Wed, 10 Apr 2024 16:09:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 74056384188C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1712765359; bh=0xuXatbokSNJAyCJ7b1NXSin5RnL6LupMsJ+RXUo3oI=; h=From:To:Subject:Date:From; b=KaWivF7QFdHBboSH2GUizdJuLb1TPNh88L7BMxwB74TiXu3DZeX7bsHDT0aPDEOZq 9NZJ5e2CTxqRCbk/rpAGt4PO49UD3d7cg8YPDqWipjqz6+uBTgv9tyvqAUiViW6agO 9+OYjyU2qv3W0CzQvhdGMlJofYkugnryVPiu46oQ= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Wilco Dijkstra To: glibc-cvs@sourceware.org Subject: [glibc/release/2.34/master] AArch64: Optimize memchr X-Act-Checkin: glibc X-Git-Author: Wilco Dijkstra X-Git-Refname: refs/heads/release/2.34/master X-Git-Oldrev: f44f5957ba15980de9f99b77e7d324e51a21160e X-Git-Newrev: a68b7934a22980b16e4207c618bf0eff7b04567c Message-Id: <20240410160919.74056384188C@sourceware.org> Date: Wed, 10 Apr 2024 16:09:19 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a68b7934a22980b16e4207c618bf0eff7b04567c commit a68b7934a22980b16e4207c618bf0eff7b04567c Author: Wilco Dijkstra 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 (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