Horton

Re: WIP: Faster Expression Processing and Tuple Deforming (including JIT)

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Markus Nullmeier <dq124@uni-heidelberg.de>
Cc: pgsql-hackers@postgresql.org
Date: 2017-02-10T18:01:03Z
Lists: pgsql-hackers 
Hi,

On 2017-02-10 18:18:13 +0100, Markus Nullmeier wrote:
> Well, if this thread of thought about hand-crafted JIT should be taken
> up again by someone at some point in time, I guess it could be possible
> to reuse tools that are already out there, such as "DynASM"
> ( http://luajit.org/dynasm_features.html ) from the LuaJIT project
> (currently offers x86-64, x86-32, ARM-32, PPC-32, and MIPS-32).
> Maybe one could even recycle parts of the LuaJIT project itself
> ( http://luajit.org/luajit.html ,
>   http://article.gmane.org/gmane.comp.lang.lua.general/58908 ).

FWIW, I'd looked at dynasm/luajit.

One big reason to go for LLVM is that it has nearly all the
infrastructure to make backend-functions/operators inlineable.
Especially for some of the arithmetic operations and such, that'd be
quite useful performance-wise.  With LLVM you can just use clang on C to
generate the IR, do some work to boil down the IR modules to the
relevant functions (i.e. remove non sql-callable functions), for which
LLVM has infrastructure, and then inline the functions that way.  That's
a lot harder to do with nearly everything else (save gcc's jit library,
but the licensing and stability situation makes that unattractive.

Greetings,

Andres Freund

Commits

  1. Improve performance of ExecEvalWholeRowVar.

  2. Remove unreachable code in expression evaluation.

  3. Faster expression evaluation and targetlist projection.

  4. Avoid syntax error on platforms that have neither LOCALE_T nor ICU.

  5. Add configure test to see if the C compiler has gcc-style computed gotos.

  6. Improve regression test coverage for TID scanning.

  7. Improve expression evaluation test coverage.

  8. Fix two errors with nested CASE/WHEN constructs.