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>
1 file changed