From 675cf53c1deaffadc7b6a0b4afe6cdafec86bedb Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Thu, 16 Apr 2015 12:43:42 -0700 Subject: [PATCH] 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 Cc: Tejun Heo Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/vsprintf.c | 10 ++++------ 1 file 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; } -- 2.20.1