Re: JIT compiling with LLVM v12.1

Hi,

On 2018-03-13 16:40:32 -0700, Andres Freund wrote:
> I've pushed a revised and rebased version of my JIT patchset.
> The git tree is at
> https://git.postgresql.org/git/users/andresfreund/postgres.git
> in the jit branch
> https://git.postgresql.org/gitweb/?p=users/andresfreund/postgres.git;a=shortlog;h=refs/heads/jit

The biggest change is that this contains docbook docs. Please check it
out, I'm not entirely sure the structure is perfect. I'll make a
language prettying pass tomorrow, to tired for that now.

> Todo:
> - some build issues with old clang versions pointed out by Thomas Munro

I've added the configure magic to properly detect capabilities of
different clang versions. This doesn't resolve the 3.4 issues Thomas had
reported however, because we still rely on -flto=thin.

If necessary we could support it by adding a 'opt -module-summary $@ -o
$@' to the %.bc rules, but that'd require some version specific
handling. Given that it doesn't yet look necessary I'm loath to go
there.

> - when to take jit_expressions into account (both exec and plan or just
> latter)

It's just plan time now. There's a new 'jit' GUC that works *both* at
execution time and plan time, and is documented as such.

> - EXPLAIN for queries that are JITed should display units. Starting
> thread about effort to not duplicate code for that

done.

> - GUC docs (including postgresql.conf.sample)

done.

> - more explanations of type & function signature syncing

Still WIP.

Greetings,

Andres Freund