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

[Emil Velikov]

On Thu, 1 Nov 2018 at 16:13, Michel Dänzer <michel at daenzer.net> wrote:
>
> 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.
>
Right, I misread the usecase :-( Sorry about that.
The following works like a charm:

.../autogen.sh ac_cv_path_LLVM_CONFIG=/...
make
touch .../configure.ac
make

>
> 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.
>
Merely following suite - see commit e2afa154e99071e8d51be88494cd1347ad113035
The series does the following:
- bumps the version
- removes build-wise LLVM hacks - now dead
- removes old LLVM codepaths - now dea

I could have split it in three, yet it seems like be a serious overkill.

That said, can we hear some directions/preferences of how to move
things forward?
I'm slightly worries that we may end up in the XKCD Workflow case :-(

Thanks
Emil