Messages in this thread Patch in this message | | | Date | Sat, 5 Jul 2014 03:47:08 -0700 | From | tip-bot for Rasmus Villemoes <> | Subject | [tip:perf/core] perf/x86: Micro-optimize nhmex_rbox_get_constraint() |
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Commit-ID: 2172c1f5aa58310784f358ca20fdddfcdc2a0d7b Gitweb: http://git.kernel.org/tip/2172c1f5aa58310784f358ca20fdddfcdc2a0d7b Author: Rasmus Villemoes <linux@rasmusvillemoes.dk> AuthorDate: Thu, 19 Jun 2014 15:15:31 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Sat, 5 Jul 2014 11:21:52 +0200
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> --- arch/x86/kernel/cpu/perf_event_intel_uncore.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c index 65bbbea..e009f3c 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;
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