[PATCH] lib/string.c: make strncmp() smaller
From: Alexey Dobriyan
Date: Fri Feb 08 2019 - 02:34:10 EST
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@xxxxxxxxx>
---
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;
}