[Mesa-maintainers] [Mesa-dev] Building Mesa GIT with LLVM prior to 3.9

[Aaron Watry]

On Tue, Sep 19, 2017 at 9:23 AM, Vedran Miletić <vedran at miletic.net> wrote:
> On 09/18/2017 06:00 PM, Emil Velikov wrote:
>> Hi all,
>>
>> As you may know, different components in Mesa use LLVM for various purposes.
>>
>> In particular:
>>  - 3.3.0 for the aux gallium module, gallivm
>>  - 3.6.0 for the opencl state-tracker, clover
>>  - 3.9.0 for multiple drivers r600, radeonsi, radv and swr
>>
>> AFAICT gallivm is build on Windows, and using newer LLVM in there is
>> rather hard/messy.
>>
>> On the other hand, Clover is built on Linux/BSD platforms. Which seems
>> to be OK wrt availability and the respective packaging.
>> So leaving the former out for now, I'm wondering if we cannot bump the
>> Clover requirement to 3.9.0.

No arguments from me.  As Jan said, libclc requires LLVM 4.0 anyway
these days, and r600/radeonsi both require 3.9 as well.

The only reason I can think of keeping 3.6 would be if someone were to
theoretically try to add CPU support to clover (e.g. just run CL on
the host processor similar to POCL's CPU support). I don't see that
being too likely at this point in time (or at least not for a while),
and even then we'd need to add CPU support to libclc, which would
effectively increase the requirement to 4.0 anyway.

--Aaron

>>
>> Quick search shows:
>>  - Debian - 3.9 since stretch (stable)
>>  - Ubuntu - 3.9 since trusty (14.04LTS)
>>  - FreeBSD - 3.9
>>  - openSUSE - 3.9 since Leap 42.2 (unofficial), official since Tumbleweed
>>  - Fedora - 3.9 since F25
>>  - Gentoo - 3.9 is marked as stable
>>  - Archlinux - using 5.0
>>
>> Note: older enterprise distributions seems to be in the cold.
>> Yet there's little point in them building Clover since it cannot be
>> run on those.
>>
>> Thanks
>> Emil
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>>
>
> I'm normally on the "let's keep it compatible as long as realistically
> possible" side, but given that all drivers that Clover works with
> already require LLVM 3.9, I'd say yes, bump the requirement (this allows
> us to get rid of three quarter of #if HAVE_LLVM version checks).
>
> Regards,
> Vedran
>
> --
> Vedran Miletić
> vedran.miletic.net
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