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>
Subject: Re: WIP: Faster Expression Processing v4
In-reply-to: <20170327054314.qo6xsnlk7jcb7u2c@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Sun, 26 Mar 2017 22:43:14 -0700"
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Date: Mon, 27 Mar 2017 09:33:43 -0400
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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


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