Proposal: Improving the LLVM backend by packaging it

Austin Seipp austin at
Fri Nov 28 20:38:33 UTC 2014

Perhaps we could have ./validate also imply the 'llvm' WAY for tests
and not just the 'fast' way (which tests the NCG). But that would
double the amount of time needed for the testsuite by itself (actually
slightly more than that, since the LLVM backend is normally slower
than the NCG). But anyway, there are opportunities for speed ups
anyway I imagine, and future Harbormaster improvements mean we could
do the llvm WAY concurrently on a separate machine.

On Fri, Nov 28, 2014 at 9:52 AM, Ben Gamari <bgamari.foss at> wrote:
> David Terei <d at> writes:
>> Late to the conversation sorry.
>> I think this sounds like a good plan. Given we are planning to stick
>> with a vanilla LLVM but just fix the version, it seems it should make
>> it reasonable to have distro’s support this. We can provide binaries
>> easily, but also just a declaration that llvm-3.4 is the current
>> supported version, so please package that and tell GHC where to find
>> it.
> Agreed.
>> We already do this in a weak way by checking which version of LLVM the
>> user is using and issuing a warning when it’s one we don’t support.
>> The other aspect that would be very useful is if all the build
>> machines tested with LLVM as well. It’s a lot of work to support LLVM
>> across all the platforms we support and to track changes across both
>> communities. Automated testing of the currently supported LLVM version
>> and LLVM-HEAD would be great.
> Absolutely, this would be amazing. I generally don't find out
> about regressions due to LLVM until I have time to build and test a
> snapshot which doesn't happen nearly as often as I would like.
> Cheers,
> - Ben


Austin Seipp, Haskell Consultant
Well-Typed LLP,

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