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From: Daniel Gustafsson <[email protected]>
To: Tom Lane <[email protected]>
Cc: XChy <[email protected]>
Cc: [email protected]
Subject: Re: Missed compiler optimization issue in function select_rtable_names_for_explain
Date: Wed, 22 May 2024 20:14:10 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <OS0P286MB016392E0B2017DDB6709A11C82EB2@OS0P286MB0163.JPNP286.PROD.OUTLOOK.COM>
	<[email protected]>
	<OS0P286MB01632009BF9AA52386BA9E4D82EB2@OS0P286MB0163.JPNP286.PROD.OUTLOOK.COM>
	<[email protected]>
	<[email protected]>

> On 22 May 2024, at 18:53, Tom Lane <[email protected]> wrote:
> 
> Daniel Gustafsson <[email protected]> writes:
>> They are known to be zero, but that's not entirely equivalent though is it?
>> NIL is defined as ((List *) NULL) and NULL is typically defined as ((void *)
>> 0), so sizeof(0) would be the size of an int and sizeof(NULL) would be the size
>> of a void pointer.
> 
> There are other places where we assume that a memset-to-zero will
> produce null pointers, so I don't think that that objection has
> a lot of force.

It wasn't really an objection, but (perhaps a badly worded) an attempt to
understand the proposal.

> My real answer is that this is our coding style
> and we are not going to change it: our normal convention is to
> initialize struct fields in declaration order, and that's what
> we're doing here.  If some particular version of some particular
> compiler fails to make an entirely-negligible optimization in
> consequence, that is not something we are going to care about.

+1

--
Daniel Gustafsson

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