Horton

Re: JIT compiling with LLVM v9.0

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Jeff Davis <pgsql@j-davis.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-01-25T07:02:54Z
Lists: pgsql-hackers 
Hi!

On 2018-01-24 22:51:36 -0800, Jeff Davis wrote:
> A couple high-level questions:
> 
> 1. I notice a lot of use of the LLVM builder, for example, in
> slot_compile_deform(). Why can't you do the same thing you did with
> function code, where you create the ".bc" at build time from plain C
> code, and then load it at runtime?

Not entirely sure what you mean. You mean why I don't inline
slot_getsomeattrs() etc and instead generate code manually?  The reason
is that the generated code is a *lot* smarter due to knowing the
specific tupledesc.


> 2. I'm glad you considered extensions. How far can we go with this in
> the future?

> Can we have bitcode-only extensions that don't need a .so
> file?

Hm. I don't see a big problem introducing this. There'd be some
complexity in how to manage the lifetime of JITed functions generated
that way, but that should be solvable.


> Can we store the bitcode in pg_proc, simplifying deployment and
> allowing extensions to travel over replication?

Yes, we could. You'd need to be a bit careful that all the machines have
similar-ish cpu generations or compile with defensive settings, but that
seems okay.

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".