Horton

Re: JIT compiling with LLVM v12

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Noah Misch <noah@leadboat.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, pgsql-hackers@postgresql.org
Date: 2018-08-22T22:15:29Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> On 2018-08-22 06:20:21 +0000, Noah Misch wrote:
>> Regardless of the choice of jit={on|off} default, these numbers tell me that
>> some or all of jit_*_cost defaults are too low.

> I don't think it really shows that. The reason that JITing gets started
> there is that the tables aren't analyzed and we end up with crazy ass
> estimates about the cost of the queries. No useful setting of the cost
> limits will protect against that... :(

I don't buy that line of argument one bit.  No, we generally don't
analyze most of the regression test tables, but the planner still
knows that they're not very large.  If JIT is kicking in for those
queries, the defaults are set wrong.  Additional evidence for the
defaults being wrong is the number of reports we've had of JIT making
things slower.

I was OK with that happening during early beta, on the grounds of getting
more testing for the JIT code; but it's time to fix the numbers.

			regards, tom lane

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".