Failures with gcd functions with GCC snapshots GCC and -O3 (?)

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Cc: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
Subject: Failures with gcd functions with GCC snapshots GCC and -O3 (?)
Date: 2021-06-03 07:26:49
Message-ID: YLiEOVpTg/7gxEVM@paquier.xyz
Views: Whole Thread | Raw Message | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Hi all,

serinus has been complaining about the new gcd functions in 13~:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=serinus&dt=2021-06-03%2003%3A44%3A14

The overflow detection is going wrong the way up and down, like here:
SELECT gcd((-9223372036854775808)::int8, (-9223372036854775808)::int8); -- overflow
-ERROR: bigint out of range
+ gcd
+----------------------
+ -9223372036854775808
+(1 row)

That seems like a compiler bug to me as this host uses recent GCC
snapshots, and I cannot see a problem in GCC 10.2 on my own dev box.
But perhaps I am missing something?

Thanks,
--
Michael

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Dean Rasheed 2021-06-03 08:28:08 Re: Failures with gcd functions with GCC snapshots GCC and -O3 (?)
Previous Message Michael Paquier 2021-06-03 06:56:25 Re: Alias collision in `refresh materialized view concurrently`