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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2015-04-16 12:43:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-17 09:03:55 -0400
commit675cf53c1deaffadc7b6a0b4afe6cdafec86bedb (patch)
treeecf7d3a546cdc560b5946b73b6163a5a20b500fc /lib
parentcdb1dc3f1ca5c5899e5fa186afe20390bd8c00dc (diff)
lib/vsprintf.c: improve put_dec_trunc8 slightly
I hadn't had enough coffee when I wrote this. Currently, the final increment of buf depends on the value loaded from the table, and causes gcc to emit a cmov immediately before the return. It is smarter to let it depend on r, since the increment can then be computed in parallel with the final load/store pair. It also shaves 16 bytes of .text. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> 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/vsprintf.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index c93ec8a035b3..da39c608a28c 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -165,9 +165,9 @@ static const u16 decpair[100] = {
/*
* This will print a single '0' even if r == 0, since we would
- * immediately jump to out_r where two 0s would be written and one of
- * them then discarded. This is needed by ip4_string below. All other
- * callers pass a non-zero value of r.
+ * immediately jump to out_r where two 0s would be written but only
+ * one of them accounted for in buf. This is needed by ip4_string
+ * below. All other callers pass a non-zero value of r.
*/
static noinline_for_stack
char *put_dec_trunc8(char *buf, unsigned r)
@@ -206,9 +206,7 @@ out_q:
out_r:
/* 1 <= r < 100 */
*((u16 *)buf) = decpair[r];
- buf += 2;
- if (buf[-1] == '0')
- buf--;
+ buf += r < 10 ? 1 : 2;
return buf;
}

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