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| author |   Alexey Dobriyan <adobriyan@gmail.com> | 2016-10-11 13:51:30 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2016-10-11 15:06:30 -0700 |
| commit | 1204c77f9b6ab8ba8cc6cfe00342f5e64a740cdf (patch) | |
| tree | 7c48ad22c756dc7b6215ac5aca362bc192efd35a /include | |
| parent | lib: harden strncpy_from_user (diff) | |
| download | linux-dev-1204c77f9b6ab8ba8cc6cfe00342f5e64a740cdf.tar.xz linux-dev-1204c77f9b6ab8ba8cc6cfe00342f5e64a740cdf.zip | |
include/linux/ctype.h: make isdigit() table lookupless
Make isdigit into a simple range checking inline function:
return '0' <= c && c <= '9';
This code is 1 branch, not 2 because any reasonable compiler can
optimize this code into SUB+CMP, so the code
while (isdigit((c = *s++)))
...
remains 1 branch per iteration HOWEVER it suddenly doesn't do table
lookup priming cacheline nobody cares about.
Link: http://lkml.kernel.org/r/20160826190047.GA12536@p183.telecom.by
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 'include')
| -rw-r--r-- | include/linux/ctype.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/ctype.h b/include/linux/ctype.h index 653589e3e30e..f13e4ff6835a 100644 --- a/include/linux/ctype.h +++ b/include/linux/ctype.h @@ -22,7 +22,10 @@ extern const unsigned char _ctype[]; #define isalnum(c) ((__ismask(c)&(_U|_L|_D)) != 0) #define isalpha(c) ((__ismask(c)&(_U|_L)) != 0) #define iscntrl(c) ((__ismask(c)&(_C)) != 0) -#define isdigit(c) ((__ismask(c)&(_D)) != 0) +static inline int isdigit(int c) +{ + return '0' <= c && c <= '9'; +} #define isgraph(c) ((__ismask(c)&(_P|_U|_L|_D)) != 0) #define islower(c) ((__ismask(c)&(_L)) != 0) #define isprint(c) ((__ismask(c)&(_P|_U|_L|_D|_SP)) != 0) |