From: Eli Zaretskii <eliz@gnu.org>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: emacs-devel@gnu.org
Subject: Re: Strange problems with data-tests.el
Date: Mon, 13 Aug 2018 18:05:06 +0300 [thread overview]
Message-ID: <83o9e6joil.fsf@gnu.org> (raw)
In-Reply-To: <486fc1b9-88a7-93e0-dd45-4f8f1d8a77d1@cs.ucla.edu> (message from Paul Eggert on Sun, 12 Aug 2018 15:43:14 -0700)
> From: Paul Eggert <eggert@cs.ucla.edu>
> Cc: emacs-devel@gnu.org
> Date: Sun, 12 Aug 2018 15:43:14 -0700
>
> I suspect that it's only bad luck that exposed the problem, that is, that the
> recent bignum or misc changes triggered the bug only because they caused GCC to
> optimize in a different way.
No, it didn't happen because of the bignum merge. I found a 26.0.90
pretest that was built with -Og, and sure enough, the problem is there
as well. And when I installed your patch in that version and
recompiled, the problem went away.
So I think this is a relatively old bug, and we should backport it to
the emacs-26 branch. WDYT?
> In theory if we're unlucky the bug could recur, since GCC doesn't
> make promises in this area. However, I changed arithcompare in such
> a way that GCC would have to be pretty perverse to cause the problem
> to resurface, and similarly for other C compilers.
Thanks.
next prev parent reply other threads:[~2018-08-13 15:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-12 18:37 Strange problems with data-tests.el Eli Zaretskii
2018-08-12 22:43 ` Paul Eggert
2018-08-13 15:05 ` Eli Zaretskii [this message]
2018-08-13 16:24 ` Paul Eggert
2018-08-13 16:49 ` Eli Zaretskii
2018-08-13 17:02 ` Paul Eggert
2018-08-13 10:06 ` Pip Cet
2018-08-13 14:44 ` Eli Zaretskii
2018-08-13 14:58 ` Pip Cet
2018-08-13 16:43 ` Paul Eggert
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