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: Stephen Frost <sfrost@snowman.net>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-03-21T21:21:01Z
Lists: pgsql-hackers 
Hi,

On 2018-03-22 10:09:23 +1300, Thomas Munro wrote:
> > FWIW, a 32bit chroot, on a 64bit kernel works:
> >
> > 2018-03-21 20:57:56.576 UTC [3708] DEBUG:  successfully loaded LLVM in current session
> > 2018-03-21 20:57:56.577 UTC [3708] DEBUG:  JIT detected CPU "skylake", with features "+sse2,+cx16,-tbm,-avx512ifma,-avx512dq,-fma4,+prfchw,+bmi2,+xsavec,+fsgsbase,+popcnt,+aes,-pcommit,+xsaves,-avx512er,-clwb,-avx512f,-pku,+smap,+mmx,-xop,+rdseed,+hle,-sse4a,-avx512bw,+clflushopt,+xsave,-avx512vl,+invpcid,-avx512cd,+avx,+rtm,+fma,+bmi,-mwaitx,+rdrnd,+sse4.1,+sse4.2,+avx2,+sse,+lzcnt,+pclmul,-prefetchwt1,+f16c,+ssse3,+sgx,+cmov,-avx512vbmi,+movbe,+xsaveopt,-sha,+adx,-avx512pf,+sse3"
> > 2018-03-21 20:57:56.579 UTC [3708] DEBUG:  time to inline: 0.000s, opt: 0.000s, emit: 0.002s
> >
> > that's debian testing though.
> 
> Hmm.  So now I'm doing this:

I've now reproduced this. It actually only fails for *some*
queries, a good number works. Investigating.


As a random aside, our costing is fairly ridiculous here:
┌──────────────────────────────────────────────────────────────────────────────┐
│                                  QUERY PLAN                                  │
├──────────────────────────────────────────────────────────────────────────────┤
│ Sort  (cost=1088314.21..1103119.40 rows=5922075 width=34)                    │
│   Sort Key: booltbl1.f1, booltbl2.f1                                         │
│   ->  Nested Loop  (cost=0.00..118524.73 rows=5922075 width=34)              │
│         Join Filter: ((booltbl2.f1 = booltbl1.f1) OR booltbl1.f1)            │
│         ->  Seq Scan on booltbl1  (cost=0.00..38.10 rows=2810 width=1)       │
│         ->  Materialize  (cost=0.00..52.15 rows=2810 width=1)                │
│               ->  Seq Scan on booltbl2  (cost=0.00..38.10 rows=2810 width=1) │
│ JIT:                                                                         │
│   Functions: 6                                                               │
│   Inlining: true                                                             │
│   Optimization: true                                                         │
└──────────────────────────────────────────────────────────────────────────────┘


> I wonder what I'm doing wrong... what you're doing is very similar,
> right?  It's a 32 bit user land on a 64 bit kernel whereas mine is a
> 32 bit user land on a 32 bit kernel (on a 64 bit CPU).

I think it's I that did something wrong not you. And the architecture
thing is a non-issue, because we're taking the target triple from the
right place.  I think it's a separate issue. Notably the generated code
is apparently corrupt, when reading in the generated bitcode:

$ opt-6.0 -O3 -S < /tmp/data/6814.1.bc|less
opt-6.0: <stdin>: error: Invalid record (Producer: 'LLVM6.0.0' Reader: 'LLVM 6.0.0')

I suspect there's a 32bit vs 64bit confusion in the expression code
somewhere, might've accidentally used a 64bit type for Datum somewhere
or such. Will compile an LLVM with assertions enabled, to figure this
out (which verifies this kinda thing).

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".