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Subject: Re: Missed compiler optimization issue in function
 select_rtable_names_for_explain
From: Daniel Gustafsson <daniel@yesql.se>
In-Reply-To: <202405221100.fy66dsew2f52@alvherre.pgsql>
Date: Wed, 22 May 2024 20:12:36 +0200
Cc: XChy <xxs_chy@outlook.com>,
 pgsql-general@postgresql.org
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References: <202405221100.fy66dsew2f52@alvherre.pgsql>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Archived-At: <https://www.postgresql.org/message-id/8912D37E-1FEB-4772-9BA2-2E5F4D940684%40yesql.se>
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> On 22 May 2024, at 13:00, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:

> I think if we want to improve how this code is seen by the compiler by
> modifying it, we should just remove the NULL/NIL assignments.

*If* the optimization is measurable, IMHO.

> It's a
> pretty arbitrary (and rather small) subset of fields being initialized,
> fields which very obviously have been zeroed by memset already, so I
> don't see any value in the explicit assignments.

My personal opinion is that there is value in immediately knowing the type of
the members from the inits, in this case I know without looking up the
definition that some of the members are list.  I like that readability.  That
being said, I for sure won't fight if there is concensus to remove.

--
Daniel Gustafsson