From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] lib/string.c: make strncmp() smaller
Date: Fri, 8 Feb 2019 10:34:03 +0300 [thread overview]
Message-ID: <20190208073403.GA19734@avx2> (raw)
Space savings on x86_64:
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-29 (-29)
Function old new delta
strncmp 67 38 -29
Space savings on arm:
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-60 (-60)
Function old new delta
strncmp 116 56 -60
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
lib/string.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
--- a/lib/string.c
+++ b/lib/string.c
@@ -344,16 +344,14 @@ EXPORT_SYMBOL(strcmp);
*/
int strncmp(const char *cs, const char *ct, size_t count)
{
- unsigned char c1, c2;
+ while (count--) {
+ unsigned int c1 = *(unsigned char *)cs++;
+ unsigned int c2 = *(unsigned char *)ct++;
- while (count) {
- c1 = *cs++;
- c2 = *ct++;
if (c1 != c2)
- return c1 < c2 ? -1 : 1;
+ return c1 - c2;
if (!c1)
break;
- count--;
}
return 0;
}
next reply other threads:[~2019-02-08 7:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 7:34 Alexey Dobriyan [this message]
2019-02-08 9:31 ` [PATCH] lib/string.c: make strncmp() smaller Joe Perches
2019-02-09 13:02 ` Alexey Dobriyan
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