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| author | Wilco Dijkstra <wilco.dijkstra@arm.com> | 2023-01-11 13:52:39 +0000 |
|---|---|---|
| committer | Wilco Dijkstra <wilco.dijkstra@arm.com> | 2023-01-17 15:09:18 +0000 |
| commit | 349e48c01e85bd96006860084e76d322e6ca02f1 (patch) | |
| tree | a25874feed2e3b5a42e875562aa8b3666e8dc90e | |
| parent | 09ebd8549b2ce5a3a6c0c7c5f3e62227faf50a99 (diff) | |
| download | glibc-349e48c01e85bd96006860084e76d322e6ca02f1.tar.gz | |
AArch64: Optimize strcpy
Unroll the main loop. Large strings are around 20% faster on modern CPUs.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
| -rw-r--r-- | sysdeps/aarch64/strcpy.S | 36 |
1 files changed, 19 insertions, 17 deletions
diff --git a/sysdeps/aarch64/strcpy.S b/sysdeps/aarch64/strcpy.S index bc14dd9f79..8b045a92c2 100644 --- a/sysdeps/aarch64/strcpy.S +++ b/sysdeps/aarch64/strcpy.S @@ -30,7 +30,6 @@ * MTE compatible. */ -/* Arguments and results. */ #define dstin x0 #define srcin x1 #define result x0 @@ -76,14 +75,14 @@ ENTRY (STRCPY) ld1 {vdata.16b}, [src] cmeq vhas_nul.16b, vdata.16b, 0 lsl shift, srcin, 2 - shrn vend.8b, vhas_nul.8h, 4 /* 128->64 */ + shrn vend.8b, vhas_nul.8h, 4 fmov synd, dend lsr synd, synd, shift cbnz synd, L(tail) ldr dataq, [src, 16]! cmeq vhas_nul.16b, vdata.16b, 0 - shrn vend.8b, vhas_nul.8h, 4 /* 128->64 */ + shrn vend.8b, vhas_nul.8h, 4 fmov synd, dend cbz synd, L(start_loop) @@ -102,13 +101,10 @@ ENTRY (STRCPY) IFSTPCPY (add result, dstin, len) ret - .p2align 4,,8 L(tail): rbit synd, synd clz len, synd lsr len, len, 2 - - .p2align 4 L(less16): tbz len, 3, L(less8) sub tmp, len, 7 @@ -141,31 +137,37 @@ L(zerobyte): .p2align 4 L(start_loop): - sub len, src, srcin + sub tmp, srcin, dstin ldr dataq2, [srcin] - add dst, dstin, len + sub dst, src, tmp str dataq2, [dstin] - - .p2align 5 L(loop): - str dataq, [dst], 16 - ldr dataq, [src, 16]! + str dataq, [dst], 32 + ldr dataq, [src, 16] + cmeq vhas_nul.16b, vdata.16b, 0 + umaxp vend.16b, vhas_nul.16b, vhas_nul.16b + fmov synd, dend + cbnz synd, L(loopend) + str dataq, [dst, -16] + ldr dataq, [src, 32]! cmeq vhas_nul.16b, vdata.16b, 0 umaxp vend.16b, vhas_nul.16b, vhas_nul.16b fmov synd, dend cbz synd, L(loop) - + add dst, dst, 16 +L(loopend): shrn vend.8b, vhas_nul.8h, 4 /* 128->64 */ fmov synd, dend + sub dst, dst, 31 #ifndef __AARCH64EB__ rbit synd, synd #endif clz len, synd lsr len, len, 2 - sub tmp, len, 15 - ldr dataq, [src, tmp] - str dataq, [dst, tmp] - IFSTPCPY (add result, dst, len) + add dst, dst, len + ldr dataq, [dst, tmp] + str dataq, [dst] + IFSTPCPY (add result, dst, 15) ret END (STRCPY) |