Horton

Re: WIP: Faster Expression Processing v4

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: Ants Aasma <ants.aasma@eesti.ee>, Heikki Linnakangas <hlinnaka@iki.fi>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2017-03-27T13:33:43Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
>> I personally find per-function annotation ala
>> __attribute__((optimize("no-crossjumping")))
>> cleaner anyway.  I tested that, and it seems to work.
>> 
>> Obviously we'd have to hide that behind a configure test.  Could also do
>> tests based on __GNUC__ / __GNUC_MINOR__, but that seems uglier.

Agreed.

> Checking for this isn't entirely pretty - see my attached attempt at
> doing so.  I considered hiding
> __attribute__((optimize("no-crossjumping"))) in execInterpExpr.c behind
> a macro (like PG_DISABLE_CROSSJUMPING), but I don't really think that
> makes things better.

I think it would, primarily because if we find out that some other compiler
spells this differently, we could handle it totally within configure.

Isn't our practice to put __attribute__ at the end of a function
declaration or definition, not in the middle someplace?

			regards, tom lane

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.