Date: Thu, 15 Aug 2024 13:45:48 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: jian he <jian.universality@gmail.com>
Cc: Joseph Koshakow <koshy44@gmail.com>,
	Heikki Linnakangas <hlinnaka@iki.fi>,
	Matthew Kim <matthewkmkim@gmail.com>,
	Alexander Lakhin <exclusion@gmail.com>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	Andres Freund <andres@anarazel.de>
Subject: Re: Remove dependence on integer wrapping
Message-ID: <Zr5M3KxOZlEZRZIN@nathan>
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On Thu, Aug 15, 2024 at 02:56:00PM +0800, jian he wrote:
> i am confused with
> "
> +#elif defined(HAVE_INT128)
> + uint128 res = -((int128) a);
> "
> I thought "unsigned" means non-negative, therefore uint128 means non-negative.
> therefore "int128  res = -((int128) a);" makes sense to me.

Ah, that's a typo, thanks for pointing it out.

> also in HAVE_INT128 branch
> do we need cast int128 to int64, like
> 
> *result = (int64) res;

I don't think we need an explicit cast here since *result is known to be an
int64.  But it certainly wouldn't hurt anything...

-- 
nathan