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authorUlrich Drepper <drepper@redhat.com>2010-07-24 08:34:44 -0700
committerUlrich Drepper <drepper@redhat.com>2010-07-24 08:34:44 -0700
commit8e96b93aa7855683d0be3c65ce81e66d0786ba84 (patch)
treeaa33ec3bf9e91c90cced716433054545109104f2
parentdbc676d4ffb074e20c6334296fc644718b485f55 (diff)
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Speed up x86-64 strcasestr a bit moew.
Using the new SSE4.2 instructions is cool but not really the fastest. Some older SSE instructions can do the trick faster.
-rw-r--r--ChangeLog5
-rw-r--r--sysdeps/x86_64/multiarch/strstr.c16
2 files changed, 16 insertions, 5 deletions
diff --git a/ChangeLog b/ChangeLog
index 46985e63e5..4a22a07972 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2010-07-24 Ulrich Drepper <drepper@redhat.com>
+
+ * sysdeps/x86_64/multiarch/strstr.c (__m128i_strloadu_tolower): Use
+ lower-latency instructions.
+
2010-07-23 Ulrich Drepper <drepper@redhat.com>
* string/test-strcasestr.c: New file.
diff --git a/sysdeps/x86_64/multiarch/strstr.c b/sysdeps/x86_64/multiarch/strstr.c
index 32ab939330..e2b19a34bc 100644
--- a/sysdeps/x86_64/multiarch/strstr.c
+++ b/sysdeps/x86_64/multiarch/strstr.c
@@ -173,11 +173,17 @@ __m128i_strloadu_tolower (const unsigned char *p, __m128i rangeuc,
{
__m128i frag = __m128i_strloadu (p);
- /* Convert frag to lower case for POSIX/C locale. */
- __m128i mask1 = _mm_cmpistrm (rangeuc, frag, 0x44);
- __m128i mask2 = _mm_blendv_epi8 (u2ldelta, frag, mask1);
- mask2 = _mm_sub_epi8 (mask2, u2ldelta);
- return _mm_blendv_epi8 (frag, mask2, mask1);
+#define UCLOW 0x4040404040404040ULL
+#define UCHIGH 0x5a5a5a5a5a5a5a5aULL
+#define LCQWORD 0x2020202020202020ULL
+ /* Compare if 'Z' > bytes. Inverted way to get a mask for byte <= 'Z'. */
+ __m128i r2 = _mm_cmpgt_epi8 (_mm_set1_epi64x (UCHIGH), frag);
+ /* Compare if bytes are > 'A' - 1. */
+ __m128i r1 = _mm_cmpgt_epi8 (frag, _mm_set1_epi64x (UCLOW));
+ /* Mask byte == ff if byte(r2) <= 'Z' and byte(r1) > 'A' - 1. */
+ __m128i mask = _mm_and_si128 (r2, r1);
+ /* Apply lowercase bit 6 mask for above mask bytes == ff. */
+ return _mm_or_si128 (frag, _mm_and_si128 (mask, _mm_set1_epi64x (LCQWORD)));
}
#endif