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authorLeonhard Holz <leonhard.holz@web.de>2015-05-12 11:37:52 +0200
committerOndřej Bílka <neleai@seznam.cz>2015-05-12 11:37:52 +0200
commitf13c2a8dff2329c6692a80176262ceaaf8a6f74e (patch)
treedd2443fba95dd55830d0d0e745a055ef3981c506 /string
parent34cb304e5a6df706e186d504b69af974bfc15a2f (diff)
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Improve strcoll with strdiff.
This patch improves strcoll hot case by finding first byte that mismatches. That is in likely case enough to determine comparison result.
Diffstat (limited to 'string')
-rw-r--r--string/strcoll_l.c38
1 files changed, 37 insertions, 1 deletions
diff --git a/string/strcoll_l.c b/string/strcoll_l.c
index 658d5b9b90..0fa005f0f9 100644
--- a/string/strcoll_l.c
+++ b/string/strcoll_l.c
@@ -29,6 +29,7 @@
# define STRING_TYPE char
# define USTRING_TYPE unsigned char
# define STRCOLL __strcoll_l
+# define STRDIFF __strdiff
# define STRCMP strcmp
# define WEIGHT_H "../locale/weight.h"
# define SUFFIX MB
@@ -41,6 +42,20 @@
#include "../locale/localeinfo.h"
#include WEIGHT_H
+#define MASK_UTF8_7BIT (1 << 7)
+#define MASK_UTF8_START (3 << 6)
+
+size_t
+STRDIFF (const STRING_TYPE *s, const STRING_TYPE *t)
+{
+ size_t n;
+
+ for (n = 0; *s != '\0' && *s++ == *t++; ++n)
+ continue;
+
+ return n;
+}
+
/* Track status while looking for sequences in a string. */
typedef struct
{
@@ -255,9 +270,29 @@ STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l)
const USTRING_TYPE *extra;
const int32_t *indirect;
+ /* In case there is no locale specific sort order (C / POSIX). */
if (nrules == 0)
return STRCMP (s1, s2);
+ /* Fast forward to the position of the first difference. Needs to be
+ encoding aware as the byte-by-byte comparison can stop in the middle
+ of a char sequence for multibyte encodings like UTF-8. */
+ uint_fast32_t encoding =
+ current->values[_NL_ITEM_INDEX (_NL_COLLATE_ENCODING_TYPE)].word;
+ if (encoding != __cet_other)
+ {
+ size_t diff = STRDIFF (s1, s2);
+ if (diff > 0)
+ {
+ if (encoding == __cet_utf8 && (*(s1 + diff) & MASK_UTF8_7BIT) != 0)
+ do
+ diff--;
+ while (diff > 0 && (*(s1 + diff) & MASK_UTF8_START) != MASK_UTF8_START);
+ s1 += diff;
+ s2 += diff;
+ }
+ }
+
/* Catch empty strings. */
if (__glibc_unlikely (*s1 == '\0') || __glibc_unlikely (*s2 == '\0'))
return (*s1 != '\0') - (*s2 != '\0');
@@ -321,7 +356,8 @@ STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l)
byte-level comparison to ensure that we don't waste time
going through multiple passes for totally equal strings
before proceeding to subsequent passes. */
- if (pass == 0 && STRCMP (s1, s2) == 0)
+ if (pass == 0 && encoding == __cet_other &&
+ STRCMP (s1, s2) == 0)
return result;
else
break;