[Mesa-dev] [PATCH 3/4] radeonsi: add more unlikely() uses into si_draw_vbo

[Ilia Mirkin]

On Mon, Sep 5, 2016 at 9:54 PM, Michel Dänzer <michel at daenzer.net> wrote:
> On 06/09/16 07:46 AM, Marek Olšák wrote:
>> From: Marek Olšák <marek.olsak at amd.com>
>
> Did you measure any significant performance boost with this change?
> Otherwise, using (un)likely can be bad because it can defeat the CPU's
> branch prediction, which tends to be pretty good these days.

Is there a way to affect the branch predictor on x86 with instruction
encodings? I didn't think so. I was under the impression that all
likely/unlikely did was to affect placement of the code, i.e. where
the "if" code was placed.

  -ilia