[Mesa-dev] A few NIR compile time optimisations

[Rob Clark]

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..

BR,
-R


>
> Marek
>
> On Wed, Feb 13, 2019 at 4:26 AM Connor Abbott <cwabbott0 at gmail.com> wrote:
>>
>> Reviewed-by: Connor Abbott <cwabbott0 at gmail.com>
>>
>> I'm a bit surprised it's that slow... do you have any idea what's going on? I've made flamegraphs in the past on i965 to see where most of the time is spent.
>>
>> On Wed, Feb 13, 2019 at 9:00 AM Timothy Arceri <tarceri at itsqueeze.com> wrote:
>>>
>>> Currently the radeonsi NIR backend takes around twice the time
>>> of the tgsi backend to compile shader-db. These are some first
>>> steps at reducing the overhead of NIR.
>>>
>>> This series reduces the compile time of a Deus Ex program I was
>>> profiling by around 5%.
>>>
>>>
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>>
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