The patch titled
Subject: include/linux/ctype.h: make isdigit() table lookupless
has been added to the -mm tree. Its filename is
make-isdigit-table-lookupless.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/make-isdigit-table-lookupless.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/make-isdigit-table-lookupless.patch
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------------------------------------------------------
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxx
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ctype.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff -puN include/linux/ctype.h~make-isdigit-table-lookupless include/linux/ctype.h
--- a/include/linux/ctype.h~make-isdigit-table-lookupless
+++ a/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)
_
Patches currently in -mm which might be from adobriyan@xxxxxxxxx are
kbuild-simpler-generation-of-assembly-constants.patch
mm-unrig-vma-cache-hit-ratio.patch
proc-much-faster-proc-vmstat.patch
proc-faster-proc-status.patch
cred-simpler-1d-supplementary-groups.patch
make-isdigit-table-lookupless.patch
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