From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>,
        Martin =?utf-8?B?TGnFoWth?= <marxin.liska@gmail.com>,
        pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #15121: Multiple UBSAN errors
In-reply-to: <20180319182705.kq2vqno7arl7r2uj@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 19 Mar 2018 11:27:05 -0700"
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Date: Mon, 19 Mar 2018 14:41:23 -0400
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Andres Freund <andres@anarazel.de> writes:
> On 2018-03-19 14:20:33 -0400, Tom Lane wrote:
>> I tried -O3 with gcc 7.3.1 (Fedora 26), and that passes check-world
>> just fine.  Then I tried -O3 with gcc 8.0.1 (prerelease Fedora 28),
>> and indeed that's got some problems.

>> Note that 1-D and 2-D arrays print fine, it's only 3-D or deeper
>> that print wrong.  Very odd.  Maybe it's bad code on our part,
>> but I think the odds are at least as good that it's a new gcc bug.

> Might be worth trying with a new clang, I think it's been a bit ahead on
> the quality of the ubsan (et al) integration quality.

I'm not talking about ubsan, I'm just talking about whether our regression
tests pass with the higher -O level.

			regards, tom lane