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[PATCH 4/4] Micro-optimize critical path of strstr, strcase and memmem.
- From: Maxim Kuvyrkov <maxim at codesourcery dot com>
- To: Carlos O'Donell <carlos at codesourcery dot com>
- Cc: GLIBC Devel <libc-alpha at sourceware dot org>, Eric Blake <eblake at redhat dot com>,Ryan Arnold <rsa at us dot ibm dot com>
- Date: Wed, 30 May 2012 21:13:17 +1200
- Subject: [PATCH 4/4] Micro-optimize critical path of strstr, strcase and memmem.
- References: <2C516CF2-D083-4C1D-AD27-6A31D381D548@codesourcery.com>
[PATCH 4/4] Micro-optimize critical path of strstr, strcase and memmem.
--
Maxim Kuvyrkov
CodeSourcery / Mentor Graphics
* string/str-two-way.h (AVAILABLE1_USES_J): New macro, define default.
(two_way_short_needle): Use it.
* string/{strstr.c, strcasestr.c} (AVAILABLE1_USES_J): Define.
---
string/str-two-way.h | 11 ++++++++++-
string/strcasestr.c | 1 +
string/strstr.c | 1 +
3 files changed, 12 insertions(+), 1 deletions(-)
diff --git a/string/str-two-way.h b/string/str-two-way.h
index b6e17e4..f1eb7d1 100644
--- a/string/str-two-way.h
+++ b/string/str-two-way.h
@@ -87,6 +87,9 @@
#ifndef RET0_IF_0
# define RET0_IF_0(a) /* nothing */
#endif
+#ifndef AVAILABLE1_USES_J
+# define AVAILABLE1_USES_J (1)
+#endif
/* Perform a critical factorization of NEEDLE, of length NEEDLE_LEN.
Return the index of the first byte in the right half, and set
@@ -298,12 +301,17 @@ two_way_short_needle (const unsigned char *haystack, size_t haystack_len,
!= (a = CANON_ELEMENT (*phaystack++)))
{
RET0_IF_0 (a);
+#if AVAILABLE1_USES_J
++j;
+#endif
continue;
}
- /* Calculate J. */
+#if !AVAILABLE1_USES_J
+ /* Calculate J if it wasn't kept up-to-date in the first-character
+ loop. */
j = phaystack - &haystack[suffix] - 1;
+#endif
/* Scan for matches in right half. */
i = suffix + 1;
@@ -500,6 +508,7 @@ two_way_long_needle (const unsigned char *haystack, size_t haystack_len,
#undef AVAILABLE
#undef AVAILABLE1
#undef AVAILABLE2
+#undef AVAILABLE1_USES_J
#undef CANON_ELEMENT
#undef CMP_FUNC
#undef RET0_IF_0
diff --git a/string/strcasestr.c b/string/strcasestr.c
index b6458ae..9467b7a 100644
--- a/string/strcasestr.c
+++ b/string/strcasestr.c
@@ -46,6 +46,7 @@
#define AVAILABLE1(h, h_l, j, n_l) (true)
#define AVAILABLE2(h, h_l, j, n_l) AVAILABLE (h, h_l, j, n_l)
#define RET0_IF_0(a) if (!a) goto ret0
+#define AVAILABLE1_USES_J (0)
#define CANON_ELEMENT(c) TOLOWER (c)
#define CMP_FUNC(p1, p2, l) \
__strncasecmp ((const char *) (p1), (const char *) (p2), l)
diff --git a/string/strstr.c b/string/strstr.c
index ec2a1e9..cfed771 100644
--- a/string/strstr.c
+++ b/string/strstr.c
@@ -38,6 +38,7 @@
#define AVAILABLE1(h, h_l, j, n_l) (true)
#define AVAILABLE2(h, h_l, j, n_l) AVAILABLE (h, h_l, j, n_l)
#define RET0_IF_0(a) if (!a) goto ret0
+#define AVAILABLE1_USES_J (0)
#include "str-two-way.h"
#undef strstr
--
1.7.4.1