Horton

Re: JIT compiling with LLVM v12.2

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-03-20T23:18:29Z
Lists: pgsql-hackers 
Hi,

On 2018-03-21 12:07:59 +1300, Thomas Munro wrote:
> The documentation builds and the resulting HTML looks good, and I like
> what you've written for users and also for developers in the README
> file.

Cool.


> Perhaps it could use something about how to know it's working
> with EXPLAIN (or any other introspection there might be), but maybe
> you're still working on that?

I'd not yet seen that as a priority, but I think it'd make sense to show
an example of that.  Perhaps showing a select query from a function,
once with that function's cost set to the default, and once with it set
to something high?


> I did a proof-reading pass and have some minor language and
> typesetting suggestions.  See comments below and attached patch
> (against current HEAD of your jit branch) which implements all of
> these changes, which of course you can feel free to take individual
> hunks from or ignore if you disagree!

Yeha!


> +   <varlistentry>
> +    <term><acronym>JIT</acronym></term>
> +    <listitem>
> +     <para>
> +      <ulink url="https://en.wikipedia.org/wiki/Just-in-time_compilation">Just
> in Time
> +      Compilation</ulink>
> +     </para>
> +    </listitem>
> +   </varlistentry>
> 
> The usual typesetting seems to be "just-in-time" (with hyphens),
> including on Wikipedia, various literature and in dictionaries.  Here
> "compilation" doesn't seem to need a capital letter (it's not part of
> the acronym, it's not otherwise in a title context where
> capitalisation is called for).

I wasn't sure about that one, thanks.



> +     <varlistentry id="guc-jit-above-cost" xreflabel="guc-jit-above-cost">
> 
> xreflabel should use underscores not hyphens, and shouldn't have the
> leading "guc" (this breaks the resulting HTML).

Oops, yea, that's definitely a mistake.


> +        Sets the planner's cutoff after which JIT compilation is used as part
> ...
> +        Sets the planner's cutoff after which JIT compiled programs (see <xref
> 
> s/after which/above which/.  I see there was some nearby text that
> used "after which", but that was talking about time.
> 
> I think writers might do s/JIT compiled/JIT-compiled/ here and some
> similar places (JIT-generated, JIT-accelerated etc), though I'm not
> sure about that and I doubt anyone cares so I didn't change it.

I was wondering about that...


Thanks a lot for going through this!

Greetings,

Andres Freund

Commits

  1. Improve JIT docs.

  2. Add documentation for the JIT feature.

  3. Add EXPLAIN support for JIT.

  4. Add inlining support to LLVM JIT provider.

  5. JIT tuple deforming in LLVM JIT provider.

  6. Add FIELDNO_* macro designating offset into structs required for JIT.

  7. Add expression compilation support to LLVM JIT provider.

  8. Expand list of synchronized types and functions in LLVM JIT provider.

  9. Add helpers for emitting LLVM IR.

  10. Basic planner and executor integration for JIT.

  11. Debugging and profiling support for LLVM JIT provider.

  12. Support for optimizing and emitting code in LLVM JIT provider.

  13. Add file containing extensions of the LLVM C API.

  14. Basic JIT provider and error handling infrastructure.

  15. Add configure infrastructure (--with-llvm) to enable LLVM support.

  16. Add C++ support to configure.

  17. Add PGAC_PROG_VARCC_VARFLAGS_OPT autoconf macro.

  18. Fix VM buffer pin management in heap_lock_updated_tuple_rec().

  19. Allow tupleslots to have a fixed tupledesc, use in executor nodes.

  20. Expression evaluation based aggregate transition invocation.

  21. Perform slot validity checks in a separate pass over expression.

  22. Rely on executor utils to build targetlist for DML RETURNING.

  23. Refer to OS X as "macOS", except for the port name which is still "darwin".