[Mesa-dev] [PATCH 08/12] configure.ac: deprecate --with-llvm-prefix

[Michel Dänzer]

On 2018-11-01 5:03 p.m., Jan Vesely wrote:
> On Wed, 2018-10-31 at 18:40 +0000, Emil Velikov wrote:
>> On Wed, 31 Oct 2018 at 17:41, Jan Vesely <jan.vesely at rutgers.edu> wrote:
>>> On Wed, 2018-10-31 at 17:22 +0000, Emil Velikov wrote:
>>>> On Wed, 31 Oct 2018 at 16:24, Michel Dänzer <michel at daenzer.net> wrote:
>>>>> On 2018-10-31 5:19 p.m., Jan Vesely wrote:
>>>>>>
>>>>>> This might be a stupid question; is the LLVM_CONFIG env var remembered
>>>>>> between reconfigure (touch configure.ac; make) or do I need to provide
>>>>>> it explicitly every time configure is run?
>>>>>
>>>>> I don't know the answer, but agree that would be a minimum requirement
>>>>> for this change.
>>>>>
>>>> Nope, yet it's not really a minimum. LLVM_CONFIG has been around for
>>>> years, it will work for any Mesa checkout since its inception.
>>>> You can safely bisect Mesa and things will just work.
>>>
>>> The question is; Do I have to do "LLVM_CONFIG=..." make every time
>>> bisect changes configure.ac?
>>>
>> You can do (although there's other options if this one seems weird)
>>
>> $ LLVM_CONFIG=... ../autogen.sh
> 
> That does not answer my question.
> 
> suppose the following sequence:
> $ LLVM_CONFIG=/usr/local/llvm-4/bin/llvm-config ../mesa-src/autogen.sh
> ...
>         llvm:            yes
>         llvm-config:     /usr/local/llvm-4/bin/llvm-config
>         llvm-version:    4.0.1
> ...
> $ make -j128
> $ touch ../mesa-src/configure.ac
> $ make -j128
> ...
>         llvm:            yes
>         llvm-config:     /usr/bin/llvm-config
>         llvm-version:    7.0.0
> ...
> 
> the second reconfigure silently reverted back to system default llvm.
> That's a loss of capabilty for me.

Thanks for checking, Jan. That's a NAK from me for this patch in the
current form.

FWIW, LLVM_CONFIG is available in the generated Makefiles, so it might
not be too hard to make this work with the environment variable. I don't
know the preferred way to do that however.


P.S. I only just now noticed the discrepancy between the commit log
talking about "deprecation", whereas the patch actually makes the option
ineffective. That's not what deprecation means. Also, I'm not sure how
this patch is related to the series' general theme of bumping the
minimum required LLVM version. Please don't bury unrelated patches in
large series.

-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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