From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] kstrtox: smaller _parse_integer()
Date: Sat, 27 Aug 2016 01:19:21 +0300 [thread overview]
Message-ID: <20160826221920.GA1909@p183.telecom.by> (raw)
Set "overflow" bit upon encountering it instead of postponing to the end
of the conversion. Somehow gcc unwedges itself and generates better code:
$ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux
_parse_integer 177 139 -38
Inspired by patch from Zhaoxiu Zeng.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
lib/kstrtox.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -48,11 +48,9 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long
{
unsigned long long res;
unsigned int rv;
- int overflow;
res = 0;
rv = 0;
- overflow = 0;
while (*s) {
unsigned int val;
@@ -71,15 +69,13 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long
*/
if (unlikely(res & (~0ull << 60))) {
if (res > div_u64(ULLONG_MAX - val, base))
- overflow = 1;
+ rv |= KSTRTOX_OVERFLOW;
}
res = res * base + val;
rv++;
s++;
}
*p = res;
- if (overflow)
- rv |= KSTRTOX_OVERFLOW;
return rv;
}
reply other threads:[~2016-08-26 22:19 UTC|newest]
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