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authorAlexey Dobriyan <adobriyan@gmail.com>2016-10-11 23:51:30 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-12 01:06:30 +0300
commit1204c77f9b6ab8ba8cc6cfe00342f5e64a740cdf (patch)
tree7c48ad22c756dc7b6215ac5aca362bc192efd35a
parentbf90e56e467ed5766722972d483e6711889ed1b0 (diff)
downloadlinux-1204c77f9b6ab8ba8cc6cfe00342f5e64a740cdf.tar.xz
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>
-rw-r--r--include/linux/ctype.h5
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)