[Mesa-dev] [PATCH 3/4] anv: Use central api generation scripts.

[Bas Nieuwenhuizen]

On Mon, Aug 13, 2018 at 5:54 PM, Dylan Baker <dylan at pnwbakers.com> wrote:
> Quoting Emil Velikov (2018-08-13 03:38:13)
>> On 10 August 2018 at 00:57, Dylan Baker <dylan at pnwbakers.com> wrote:
>> > Quoting Chad Versace (2018-08-09 10:37:33)
>> >> On Tue 07 Aug 2018, Dylan Baker wrote:
>> >> > Quoting Bas Nieuwenhuizen (2018-08-07 16:14:33)
>> >> > >
>> >> > >  anv_extensions_c = custom_target(
>> >> > > @@ -36,10 +37,11 @@ anv_extensions_c = custom_target(
>> >> > >    input : ['anv_extensions_gen.py', vk_api_xml],
>> >> > >    output : 'anv_extensions.c',
>> >> > >    command : [
>> >> > > +   'env', 'PYTHONPATH=@0@'.format(join_paths(meson.source_root(), 'src/vulkan/util/')),
>> >> >
>> >> > This is really gross, you're adding a dependency on a unix console command. I
>> >> > know that anv is only built on Unix-like oses, but this will eventually end up
>> >> > being used in some code that needs to run on Windows (or mac, does mac have
>> >> > env?).
>> >> >
>> >> > I know that some people will object, but IMHO a better solution than mucking
>> >> > with the python path (either through sys.path or through PYTHONPATH, is to
>> >> > put all of the generators in a src/generators directory and be done with it.
>> >> > Sure the intel specific bits (for example) aren't in the src/intel folder,
>> >> > that's a small price to avoid having to call env just to run a python script.
>> >>
>> >> Dylan, I think we should avoid introducing complexity in the build
>> >> system for the benefit of operating systems not supported by the driver.
>> >> That feels like a serious premature optimazation, to me.  Anvil's usage
>> >> of ioctls is highly specific to Linux/Unix, will not work on MacOS, and
>> >> definitely does not work on Windows.
>> >
>> > I agree completely. I think where we disagree is on whether mucking with
>> > PYTHONPATH and using env is more complex or putting our generators in a single
>> > directory is more complex. I think using env is extremely gross and complex, I
>> > think mucking with PYTHONPATH is extremely gross and complex, and I think having
>> > to reference a file from another directory is a *lot* less gross and *much* less
>> > complex.
>> >
>> Can we reuse the NIR approach seen here [1] [2]?
>> Moving files around just to appease python feels wrong on many levels :-(
>>
>> Thanks
>> Emil
>>
>> [1] https://gitlab.freedesktop.org/mesa/mesa/blob/master/src/intel/compiler/meson.build#L120
>> [2] https://gitlab.freedesktop.org/mesa/mesa/blob/master/src/gallium/drivers/freedreno/meson.build#L21
>
> I would begrudgingly accept that.
>
> I really don't understand why this is such a big deal. Imagine for a moment that
> a there was a driver for "Magical Unicorn" hardware existed. Imagine it had some
> very odd instructions and the developers of the Magic Unicorn driver wanted some
> special NIR passes for their hardware. Now lets imagine that they insisted that
> those passes must live in src/unicorn, but should be linked into libnir. No one
> would accept that, they would be told either to keep the passes in their backend
> or to move them into src/compiler/nir. I believe this is an analogous situation.
> We want to share code, so we're putting it in src/util/vulkan, but then instead
> of calling a generator out of src/util/vulkan in src/intel and src/amd (we
> already call python scripts from different directories all over the build
> system), we do some elaborate environment variable manipulation which can have
> unforseen side effects (like that google sets PYTHONPATH in their distro) and
> have to wrap our actual callable with `env`, just so that we could put the
> callable in src/intel and src/amd instead of having a callable in
> src/util/vulkan. Does no one else think that this is a bit crazy?

For the main functions of the generators scripts I agree and can merge
them a bit further. However the one where I think moving it is
somewhat crazy is the {radv,anv}_extensions.py, in particular the list
of supported extensions and the (driver-specific) conditions in which
they should be enabled. That seems way driver-specific to put in a
shared directory.

>
> Dylan
>
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