From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] smaller strlen()
Date: Fri, 26 Aug 2016 23:01:20 +0300 [thread overview]
Message-ID: <20160826200120.GA1852@p183.telecom.by> (raw)
gcc prefers "*s++" style code for some reason, doesn't unroll loop
condition check once. Kernel strings are small but they aren't of 0
length, so that additional branch was almost never taken.
$ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux
strlen 30 26 -4
strlcpy 71 64 -7
strlcat 120 99 -21
strlcpy() and strlcat() are collateral damage :^)
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
lib/string.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/lib/string.c
+++ b/lib/string.c
@@ -476,11 +476,11 @@ EXPORT_SYMBOL(strim);
*/
size_t strlen(const char *s)
{
- const char *sc;
+ const char *s0 = s;
- for (sc = s; *sc != '\0'; ++sc)
+ while (*s++)
/* nothing */;
- return sc - s;
+ return s - s0 - 1;
}
EXPORT_SYMBOL(strlen);
#endif
next reply other threads:[~2016-08-26 20:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-26 20:01 Alexey Dobriyan [this message]
2016-08-26 22:23 ` [PATCH] smaller strlen() Joe Perches
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