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authorAlexey Dobriyan <adobriyan@gmail.com>2017-07-11 00:51:41 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-11 01:32:34 +0200
commitbe5f3c7774a158c5bd08de22d54b0612f954dfa8 (patch)
tree1db36ebd3507d7e5f294546c9f94db18af140db5 /lib
parentlib/kstrtox.c: delete end-of-string test (diff)
downloadlinux-be5f3c7774a158c5bd08de22d54b0612f954dfa8.tar.xz
linux-be5f3c7774a158c5bd08de22d54b0612f954dfa8.zip
lib/kstrtox.c: use "unsigned int" more
gcc does generates stupid code sign extending data back and forth. Help by using "unsigned int". add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-61 (-61) function old new delta _parse_integer 128 123 -5 It _still_ does generate useless MOVSX but I don't know how to delete it: 0000000000000070 <_parse_integer>: ... a0: 89 c2 mov edx,eax a2: 83 e8 30 sub eax,0x30 a5: 83 f8 09 cmp eax,0x9 a8: 76 11 jbe bb <_parse_integer+0x4b> aa: 83 ca 20 or edx,0x20 ad: 0f be c2 ===> movsx eax,dl <=== useless b0: 8d 50 9f lea edx,[rax-0x61] b3: 83 fa 05 cmp edx,0x5 Patch also helps on embedded archs which generally only like "int". On arm "and 0xff" is generated which is waste because all values used in comparisons are positive. Link: http://lkml.kernel.org/r/20170514194720.GB32563@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/kstrtox.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/lib/kstrtox.c b/lib/kstrtox.c
index 90013f4841c7..720144075c1e 100644
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -52,12 +52,14 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long
res = 0;
rv = 0;
while (1) {
+ unsigned int c = *s;
+ unsigned int lc = c | 0x20; /* don't tolower() this line */
unsigned int val;
- if ('0' <= *s && *s <= '9')
- val = *s - '0';
- else if ('a' <= _tolower(*s) && _tolower(*s) <= 'f')
- val = _tolower(*s) - 'a' + 10;
+ if ('0' <= c && c <= '9')
+ val = c - '0';
+ else if ('a' <= lc && lc <= 'f')
+ val = lc - 'a' + 10;
else
break;