Re: JIT compiling with LLVM v9.0

From: Andres Freund <andres(at)anarazel(dot)de>
To: Pierre Ducroquet <p(dot)psql(at)pinaraf(dot)info>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: JIT compiling with LLVM v9.0
Date: 2018-01-25 19:12:42
Message-ID: 20180125191242.iqe6u7r3jq3ug3pi@alap3.anarazel.de
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Hi,

On 2018-01-25 10:00:14 +0100, Pierre Ducroquet wrote:
> I don't know when this would be released,

August-October range.

> but the minimal supported LLVM
> version will have a strong influence on the availability of that feature. If
> today this JIT compiling was released with only LLVM 5/6 support, it would be
> unusable for most Debian users (llvm-5 is only available in sid). Even llvm 4
> is not available in latest stable.
> I'm already trying to build with llvm-4 and I'm going to try further with llvm
> 3.9 (Debian Stretch doesn't have a more recent than this one, and I won't have
> something better to play with my data), I'll keep you informed. For sport, I
> may also try llvm 3.5 (for Debian Jessie).

I don't think it's unreasonable to not support super old llvm
versions. This is a complex feature, and will take some time to
mature. Supporting too many LLVM versions at the outset will have some
cost. Versions before 3.8 would require supporting mcjit rather than
orc, and I don't think that'd be worth doing. I think 3.9 might be a
reasonable baseline...

Greetings,

Andres Freund

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