| Message ID | PAWPR08MB89829827FB8D528B37AB2ED783FD9@PAWPR08MB8982.eurprd08.prod.outlook.com |
|---|---|
| State | New |
| Headers | show |
| Series | AArch64: Optimize memchr | expand |
The 01/12/2023 15:56, Wilco Dijkstra wrote: > Optimize the main loop - large strings are 40% faster on modern CPUs. > Passes regress. please commit it, thanks. Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com> > > --- > > diff --git a/sysdeps/aarch64/memchr.S b/sysdeps/aarch64/memchr.S > index 1cd32bf8cffa82d665304d54d2a4d4f75d4ff541..1c99d45fbb506c86a1db5b4d45de49b33d8635c9 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 >
diff --git a/sysdeps/aarch64/memchr.S b/sysdeps/aarch64/memchr.S index 1cd32bf8cffa82d665304d54d2a4d4f75d4ff541..1c99d45fbb506c86a1db5b4d45de49b33d8635c9 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