148 lines
4.7 KiB
Diff
148 lines
4.7 KiB
Diff
From 30d627d477d7255345a4b713cf352ac32d644d61 Mon Sep 17 00:00:00 2001
|
|
From: Noah Goldstein <goldstein.w.n@gmail.com>
|
|
Date: Wed, 23 Mar 2022 16:57:22 -0500
|
|
Subject: [PATCH] x86: Optimize strcspn and strpbrk in strcspn-c.c
|
|
Content-type: text/plain; charset=UTF-8
|
|
|
|
Use _mm_cmpeq_epi8 and _mm_movemask_epi8 to get strlen instead of
|
|
_mm_cmpistri. Also change offset to unsigned to avoid unnecessary
|
|
sign extensions.
|
|
|
|
geometric_mean(N=20) of all benchmarks that dont fallback on
|
|
sse2/strlen; New / Original: .928
|
|
|
|
All string/memory tests pass.
|
|
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
|
|
---
|
|
sysdeps/x86_64/multiarch/strcspn-c.c | 83 +++++++++++++---------------
|
|
1 file changed, 37 insertions(+), 46 deletions(-)
|
|
|
|
diff --git a/sysdeps/x86_64/multiarch/strcspn-c.c b/sysdeps/x86_64/multiarch/strcspn-c.c
|
|
index 857af104..6cce4296 100644
|
|
--- a/sysdeps/x86_64/multiarch/strcspn-c.c
|
|
+++ b/sysdeps/x86_64/multiarch/strcspn-c.c
|
|
@@ -85,83 +85,74 @@ STRCSPN_SSE42 (const char *s, const char *a)
|
|
RETURN (NULL, strlen (s));
|
|
|
|
const char *aligned;
|
|
- __m128i mask;
|
|
- int offset = (int) ((size_t) a & 15);
|
|
+ __m128i mask, maskz, zero;
|
|
+ unsigned int maskz_bits;
|
|
+ unsigned int offset = (unsigned int) ((size_t) a & 15);
|
|
+ zero = _mm_set1_epi8 (0);
|
|
if (offset != 0)
|
|
{
|
|
/* Load masks. */
|
|
aligned = (const char *) ((size_t) a & -16L);
|
|
__m128i mask0 = _mm_load_si128 ((__m128i *) aligned);
|
|
-
|
|
- mask = __m128i_shift_right (mask0, offset);
|
|
+ maskz = _mm_cmpeq_epi8 (mask0, zero);
|
|
|
|
/* Find where the NULL terminator is. */
|
|
- int length = _mm_cmpistri (mask, mask, 0x3a);
|
|
- if (length == 16 - offset)
|
|
- {
|
|
- /* There is no NULL terminator. */
|
|
- __m128i mask1 = _mm_load_si128 ((__m128i *) (aligned + 16));
|
|
- int index = _mm_cmpistri (mask1, mask1, 0x3a);
|
|
- length += index;
|
|
-
|
|
- /* Don't use SSE4.2 if the length of A > 16. */
|
|
- if (length > 16)
|
|
- return STRCSPN_SSE2 (s, a);
|
|
-
|
|
- if (index != 0)
|
|
- {
|
|
- /* Combine mask0 and mask1. We could play games with
|
|
- palignr, but frankly this data should be in L1 now
|
|
- so do the merge via an unaligned load. */
|
|
- mask = _mm_loadu_si128 ((__m128i *) a);
|
|
- }
|
|
- }
|
|
+ maskz_bits = _mm_movemask_epi8 (maskz) >> offset;
|
|
+ if (maskz_bits != 0)
|
|
+ {
|
|
+ mask = __m128i_shift_right (mask0, offset);
|
|
+ offset = (unsigned int) ((size_t) s & 15);
|
|
+ if (offset)
|
|
+ goto start_unaligned;
|
|
+
|
|
+ aligned = s;
|
|
+ goto start_loop;
|
|
+ }
|
|
}
|
|
- else
|
|
- {
|
|
- /* A is aligned. */
|
|
- mask = _mm_load_si128 ((__m128i *) a);
|
|
|
|
- /* Find where the NULL terminator is. */
|
|
- int length = _mm_cmpistri (mask, mask, 0x3a);
|
|
- if (length == 16)
|
|
- {
|
|
- /* There is no NULL terminator. Don't use SSE4.2 if the length
|
|
- of A > 16. */
|
|
- if (a[16] != 0)
|
|
- return STRCSPN_SSE2 (s, a);
|
|
- }
|
|
+ /* A is aligned. */
|
|
+ mask = _mm_loadu_si128 ((__m128i *) a);
|
|
+ /* Find where the NULL terminator is. */
|
|
+ maskz = _mm_cmpeq_epi8 (mask, zero);
|
|
+ maskz_bits = _mm_movemask_epi8 (maskz);
|
|
+ if (maskz_bits == 0)
|
|
+ {
|
|
+ /* There is no NULL terminator. Don't use SSE4.2 if the length
|
|
+ of A > 16. */
|
|
+ if (a[16] != 0)
|
|
+ return STRCSPN_SSE2 (s, a);
|
|
}
|
|
|
|
- offset = (int) ((size_t) s & 15);
|
|
+ aligned = s;
|
|
+ offset = (unsigned int) ((size_t) s & 15);
|
|
if (offset != 0)
|
|
{
|
|
+ start_unaligned:
|
|
/* Check partial string. */
|
|
aligned = (const char *) ((size_t) s & -16L);
|
|
__m128i value = _mm_load_si128 ((__m128i *) aligned);
|
|
|
|
value = __m128i_shift_right (value, offset);
|
|
|
|
- int length = _mm_cmpistri (mask, value, 0x2);
|
|
+ unsigned int length = _mm_cmpistri (mask, value, 0x2);
|
|
/* No need to check ZFlag since ZFlag is always 1. */
|
|
- int cflag = _mm_cmpistrc (mask, value, 0x2);
|
|
+ unsigned int cflag = _mm_cmpistrc (mask, value, 0x2);
|
|
if (cflag)
|
|
RETURN ((char *) (s + length), length);
|
|
/* Find where the NULL terminator is. */
|
|
- int index = _mm_cmpistri (value, value, 0x3a);
|
|
+ unsigned int index = _mm_cmpistri (value, value, 0x3a);
|
|
if (index < 16 - offset)
|
|
RETURN (NULL, index);
|
|
aligned += 16;
|
|
}
|
|
- else
|
|
- aligned = s;
|
|
|
|
+start_loop:
|
|
while (1)
|
|
{
|
|
__m128i value = _mm_load_si128 ((__m128i *) aligned);
|
|
- int index = _mm_cmpistri (mask, value, 0x2);
|
|
- int cflag = _mm_cmpistrc (mask, value, 0x2);
|
|
- int zflag = _mm_cmpistrz (mask, value, 0x2);
|
|
+ unsigned int index = _mm_cmpistri (mask, value, 0x2);
|
|
+ unsigned int cflag = _mm_cmpistrc (mask, value, 0x2);
|
|
+ unsigned int zflag = _mm_cmpistrz (mask, value, 0x2);
|
|
if (cflag)
|
|
RETURN ((char *) (aligned + index), (size_t) (aligned + index - s));
|
|
if (zflag)
|
|
--
|
|
GitLab
|
|
|