Commit 8da53d4595a53fb9a3380dd4d1c9bc24c7c9aab8
("lib/string.c: improve strrchr()") changed strrchr() implementation
from "rewind to the end and search backwards" to "search forward"
optimizing for characher not found case. However, common case is exactly
the opposite: string is absolute pathname, c is '/' always to be found.
Previous code did 1 branch per character + 1 branch for every character
in the last path component. Current code does 2 branches per characher
regardless.
Patch reverts to previous implementation (sans fixed coding style).
Signed-off-by: Alexey Dobriyan <adobri...@gmail.com>
---
Cc linux-kernel
lib/string.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/lib/string.c
+++ b/lib/string.c
@@ -313,12 +313,13 @@ EXPORT_SYMBOL(strchrnul);
*/
char *strrchr(const char *s, int c)
{
- const char *last = NULL;
+ const char *p = s + strlen(s);
+
do {
- if (*s == (char)c)
- last = s;
- } while (*s++);
- return (char *)last;
+ if (*p == (char)c)
+ return (char *)p;
+ } while (--p >= s);
+ return NULL;
}
EXPORT_SYMBOL(strrchr);
#endif
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