From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Thu, 19 Jun 2014 13:15:31 +0000 (+0200)
Subject: perf/x86: Micro-optimize nhmex_rbox_get_constraint()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=2172c1f5aa58310784f358ca20fdddfcdc2a0d7b;p=openwrt%2Fstaging%2Fblogic.git

perf/x86: Micro-optimize nhmex_rbox_get_constraint()

Flipping the LSB doesn't require four lines of code. This shaves a few
bytes of the generated code, including a branch.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1403183731-15402-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
index 65bbbea38b9c..e009f3cedf89 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -2946,10 +2946,7 @@ again:
 		 * extra registers. If we failed to take an extra
 		 * register, try the alternative.
 		 */
-		if (idx % 2)
-			idx--;
-		else
-			idx++;
+		idx ^= 1;
 		if (idx != reg1->idx % 6) {
 			if (idx == 2)
 				config1 >>= 8;