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| author | Wilco Dijkstra <wilco.dijkstra@arm.com> | 2023-01-11 13:50:59 +0000 |
|---|---|---|
| committer | Wilco Dijkstra <wilco.dijkstra@arm.com> | 2024-04-09 18:37:21 +0100 |
| commit | 50ebfdfe8a9e6f0695941d023277d4dd8b95be9a (patch) | |
| tree | f373eb91e32a489d0245772d88e86d0dda67a6b4 | |
| parent | fa9cd4fd3c45fec2211a4603777fec2e0501f32b (diff) | |
| download | glibc-50ebfdfe8a9e6f0695941d023277d4dd8b95be9a.tar.gz glibc-50ebfdfe8a9e6f0695941d023277d4dd8b95be9a.tar.xz glibc-50ebfdfe8a9e6f0695941d023277d4dd8b95be9a.zip | |
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)
| -rw-r--r-- | sysdeps/aarch64/memchr.S | 27 |
1 files 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 |