[llvm-foundation] Minimum Requirement Infrastructure

[Hal Finkel via llvm-foundation]

----- Original Message -----
> From: "Renato Golin via llvm-foundation" <llvm-foundation at lists.llvm.org>
> To: "Renato Golin via llvm-foundation" <llvm-foundation at lists.llvm.org>
> Sent: Tuesday, October 18, 2016 5:40:54 AM
> Subject: [llvm-foundation] Minimum Requirement Infrastructure
> 
> Hi folks,
> 
> A number of threads have sparked discussions about minimum toolchain
> requirements and a few of them have shown that we're very poor in
> keeping track of our promises.
> 
> The main issue is that we're not publicly testing our minimum
> requirements.
> 
> We claim clang 3.1 can compile all LLVM projects, but no one has a
> buildbot with that version, even with just LLVM and Clang. Recently,
> libc++ has broken with clang 3.6, and that's because I've upgraded
> our
> bot to 3.9 and stopped tracking.
> 
> We (Linaro) need to stay on top of what people are using, not LLVM's
> minimum requirements, as we have found a number of issues when
> migrating to the current LTS platform (Ubuntu Xenial), and that's
> what
> people are using on ARM right now. So we cannot keep testing all
> platforms, and I assume this is true for all companies that
> contribute
> to LLVM.
> 
> For that reason, I propose that the Foundation should set some funds
> to have x86_64 machines (cloud instances are fine) with the minimum
> requirements for at least one Linux build with minimum Clang and one
> with minimum GCC.
> 
> I don't know if it's possible to have OSX on the cloud, or if it's
> easy to have a Windows machine in the same way, but that'd be "in
> addition" to the Linux machine. MSVC 2015 support can be tested by
> those that have the license, I'm not proposing the Foundation to
> purchase it.
> 
> The preference for Linux is that it's easier to deploy and control on
> the cloud (and it's free), and we're testing the compilation process,
> not the functionality (which should be tested elsewhere).
> 
> Having a single machine for both GCC and Clang builds should be ok,
> since we don't need too many builds a day, and compilation errors are
> easy to spot, even on a large commit range. Even if we had one build
> each, every day, it would be fine. A dual core cloud instance with
> 4GB
> of RAM would be more than enough.
> 
> Can the foundation spare resources for that usage?
> 
> If not, do we have another way to ensure the support of minimum
> compilers to our projects?
> 
> Do we track sub-projects like LLD, LLDB, Compiler-RT and libc++
> separately? We must track them, too.

Regarding this last question, I think we should discuss this on llvm-dev. Perhaps a separate thread would be appropriate. How we specify our minimum requirements across the various LLVM projects is something we need to discuss with a wide audience, and is a technical matter. We definitely don't do a good job now, either with the specification or the testing, in this regard.

 -Hal

> 
> cheers,
> --renato
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-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory