[Mesa-dev] RFC uniform packing for gallium V2

[Nicolai Hähnle]

I had a chance to look at the patches in detail now. Thanks for working 
on this, it should be quite useful!

With the remark on patch 1 addressed, patches 1, 2, and 4-9 are

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

I've sent some more extensive comments on patch 3, and I already 
explained that I don't like the TGSI changes. I do think it should be 
possible to emit a LOAD instead.

Thanks,
Nicolai


On 25.06.2017 03:31, Timothy Arceri wrote:
> There are still a handful of piglit tests failing and I'm yet to test
> that there are no regressions in the non-packed path, but I'd really
> like some feedback on the approach as Dave has flagged it as a possible
> controversial tgsi change.
> 
> In order to avoid complicated swizzling and array element adjustments
> when dealing with arrays, this series simply adjusts the constant buffer
> index to point to the right location. There are some small changes to
> deal with indirect indexing but these also remain very simple and easy
> to follow.
> 
> Dave has raised concerns that others might not like this as it doesn't
> strictly follow the tgsi approach that everything is a vec4. I would
> argue however that this is by far the simplest approch.
> Doing this with swizzles and array adjustments is going to require
> something like lower_packed_varyings.cpp which would be unnecessarily
> complicated IMO, I started off down that track and soon changed
> direction.
> 
> The main goal of this series is to reduce the cpu overhead cause by
> _mesa_propagate_uniforms_to_driver_storage(). The function is slow since we
> need to deal with strides etc because we are copying packed data to an
> unpacked destination. It's also copying data that we have only just copied
> to anouther duplicate uniform storage that gets created by the linker.
> 
> This series fixes both of these issues and also reduces the size of the
> drivers const buffer as a side effect.
> 
> Patches 2-3 just rework the way we use the param list.
> 
> The remaining add the packing support enabled by the
> PackedDriverUniformStorage const.
> 
> You can get the series in my test4 branch [1].
> 
> [1] https://github.com/tarceri/Mesa.git
> 
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