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| author | Xuelei Zhang <zhangxuelei4@huawei.com> | 2019-12-19 13:41:40 +0000 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2019-12-19 16:31:04 -0300 |
| commit | c2150769d015dca1805334af7743829f1e4c0b6a (patch) | |
| tree | 9a57061392d7a63e1696ab208005677b3968bfce /sysdeps/aarch64/multiarch/strlen_asimd.S | |
| parent | 0db8e7b36665fa90c53161742dedab21d786924c (diff) | |
| download | glibc-c2150769d015dca1805334af7743829f1e4c0b6a.tar glibc-c2150769d015dca1805334af7743829f1e4c0b6a.tar.gz glibc-c2150769d015dca1805334af7743829f1e4c0b6a.tar.bz2 glibc-c2150769d015dca1805334af7743829f1e4c0b6a.zip | |
aarch64: Optimized strlen for strlen_asimd
Optimize the strlen implementation by using vector operations and
loop unrolling in main loop.Compared to __strlen_generic,it reduces
latency of cases in bench-strlen by 7%~18% when the length of src
is greater than 128 bytes, with gains throughout the benchmark.
Checked on aarch64-linux-gnu.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Diffstat (limited to 'sysdeps/aarch64/multiarch/strlen_asimd.S')
| -rw-r--r-- | sysdeps/aarch64/multiarch/strlen_asimd.S | 42 |
1 files changed, 26 insertions, 16 deletions
diff --git a/sysdeps/aarch64/multiarch/strlen_asimd.S b/sysdeps/aarch64/multiarch/strlen_asimd.S index 1d1c6abb82..1de6cd3a17 100644 --- a/sysdeps/aarch64/multiarch/strlen_asimd.S +++ b/sysdeps/aarch64/multiarch/strlen_asimd.S @@ -48,6 +48,9 @@ #define dataq2 q3 #define datav2 v3 +#define REP8_01 0x0101010101010101 +#define REP8_7f 0x7f7f7f7f7f7f7f7f + #ifdef TEST_PAGE_CROSS # define MIN_PAGE_SIZE 16 #else @@ -82,40 +85,47 @@ ENTRY_ALIGN (__strlen_asimd, 6) DELOUSE (0) DELOUSE (1) and tmp1, srcin, MIN_PAGE_SIZE - 1 + mov zeroones, REP8_01 cmp tmp1, MIN_PAGE_SIZE - 16 b.gt L(page_cross) - ldr dataq, [srcin] + ldp data1, data2, [srcin] #ifdef __AARCH64EB__ - rev64 datav.16b, datav.16b + rev data1, data1 + rev data2, data2 #endif - /* Get the minimum value and keep going if it is not zero. */ - uminv datab2, datav.16b - mov tmp1, datav2.d[0] - cbnz tmp1, L(main_loop_entry) - - cmeq datav.16b, datav.16b, #0 - mov data1, datav.d[0] - mov data2, datav.d[1] - cmp data1, 0 - csel data1, data1, data2, ne + sub tmp1, data1, zeroones + orr tmp2, data1, REP8_7f + sub tmp3, data2, zeroones + orr tmp4, data2, REP8_7f + bics has_nul1, tmp1, tmp2 + bic has_nul2, tmp3, tmp4 + ccmp has_nul2, 0, 0, eq + beq L(main_loop_entry) + csel has_nul1, has_nul1, has_nul2, cc mov len, 8 - rev data1, data1 - clz tmp1, data1 - csel len, xzr, len, ne + rev has_nul1, has_nul1 + clz tmp1, has_nul1 + csel len, xzr, len, cc add len, len, tmp1, lsr 3 ret L(main_loop_entry): bic src, srcin, 15 + sub src, src, 16 L(main_loop): - ldr dataq, [src, 16]! + ldr dataq, [src, 32]! L(page_cross_entry): /* Get the minimum value and keep going if it is not zero. */ uminv datab2, datav.16b mov tmp1, datav2.d[0] + cbz tmp1, L(tail) + ldr dataq, [src, 16] + uminv datab2, datav.16b + mov tmp1, datav2.d[0] cbnz tmp1, L(main_loop) + add src, src, 16 L(tail): #ifdef __AARCH64EB__ |