Horton

Re: JIT compiling with LLVM v11

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Pg Hackers <pgsql-hackers@postgresql.org>, Pierre Ducroquet <p.psql@pinaraf.info>
Date: 2018-03-05T20:17:30Z
Lists: pgsql-hackers 
Hi,

On 2018-03-04 21:00:06 -0800, Andres Freund wrote:
> > Looking at llvm_get_function(), the function that raises that error, I
> > see that there are a few different paths here.  I don't have
> > HAVE_DECL_LLVMORCGETSYMBOLADDRESSIN defined, and I don't have LLVM <
> > 5, so I should be getting the symbol address with
> > LLVMOrcGetSymbolAddress(llvm_opt0_orc, &addr, mangled) or
> > LLVMOrcGetSymbolAddress(llvm_opt3_orc, &addr, mangled), but clearly
> > those are returning NULL.
> 
> Yep. I wonder if this is some symbol naming issue or such, because
> emitting and relocating the object worked without an error.

Thanks to Thomas helping get access to an OSX machine I was able to
discover what the issue is.  OSX prepends, for reason unbeknownst to me,
a leading underscore to all function names.  That lead to two issues:
First JITed functions do not have that underscore (making us look up a
non-existing symbol, because llvm_get_function applied
mangling). Secondly, llvm_resolve_symbol failed looking up symbol names,
because for $reason dlsym() etc do *not* have the names prefixed by the
underscore.   Easily enough fixed.

After that I discovered another problem, the bitcode files for core pg /
contrib modules weren't installed. That turned out to be a make version
issue, I'd used
define install_llvm_module =
# body
but older make only like
define install_llvm_module
# body

Writing up a patch that I can actually push.  Thanks both to Thomas and
Peter for pointing me towards this issue!

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".