Commit 2172c1f5 authored Jun 19, 2014 by Rasmus Villemoes Committed by Ingo Molnar Jul 05, 2014

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>

parent 985c8dcb

arch/x86/kernel/cpu/perf_event_intel_uncore.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -2946,10 +2946,7 @@ nhmex_rbox_get_constraint(struct intel_uncore_box box, struct perf_event event
		* 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;