[Mesa-dev] A few NIR compile time optimisations

Marek Olšák maraeo at gmail.com
Wed Feb 20 03:28:24 UTC 2019

On Tue, Feb 19, 2019 at 7:57 PM Rob Clark <robdclark at gmail.com> wrote:

> On Tue, Feb 19, 2019 at 6:49 PM Marek Olšák <maraeo at gmail.com> wrote:
> >
> > st_link_shader takes 55% of CPU time with NIR, and 9% with TGSI.
> >
> > nir_validate_shader 49%
> >
> > nir_validate_shader is overused. It doesn't make sense even in debug
> builds.
> tbh, I like nir_validate enabled when I do piglit/deqp runs.. and I
> already do separate release vs debug builds (which meson kinda
> encourages by disallowing in-tree builds in the first place, but is
> totally possible with autotools builds).. I kinda think benchmarking
> debug build in the first place is a flawed process.
> So I wouldn't profile/benchmark nir vs tgsi (or really anything) with
> debug builds.. I could get behind a separate compiler-debug option
> that changed the default NIR_VALIDATE setting and maybe some other nir
> debug features to get some features of debug builds without enabling
> the heavier nir debug features.  But other than making debug options a
> bit more fine grained, I wouldn't change things in response to a
> flawed benchmarking process..

That's a harsh reaction to a relatively good benchmarking setup. I use
debugoptimized with -DDEBUG. My performance is probably more affected by
-fno-omit-frame-pointer than -DDEBUG.

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