From: Jakub Jelinek <jakub@redhat.com>
To: Aldy Hernandez <aldyh@redhat.com>
Cc: Richard Biener <richard.guenther@gmail.com>,
Richard Henderson <rth@gcc.gnu.org>,
GCC patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] frange: flush denormals to zero for -funsafe-math-optimizations.
Date: Tue, 20 Sep 2022 10:26:21 +0200 [thread overview]
Message-ID: <Yyl5LTBkou/0TWRn@tucnak> (raw)
In-Reply-To: <CAGm3qMW=+wfZMkB8Lx93hhytjaWLwYzQcfPm-HsnU9g_Zh3-VQ@mail.gmail.com>
On Tue, Sep 20, 2022 at 07:22:03AM +0200, Aldy Hernandez wrote:
> > > Jakub actually suggested something completely different...just set +0
> > > always for !HONOR_SIGNED_ZEROS.
> >
> > Hmm, but the [-1, -0.] with known sign becomes [-1, +0.] with unknown sign?
>
> Huh. I guess that's true. Does that happen often enough in practice
Sure, if you -fno-signed-zeros/-ffast-math and some variable can be zero,
copysign/signbit is undefined. The option basically asserts you don't care
about it...
Jakub
prev parent reply other threads:[~2022-09-20 8:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-17 8:24 Aldy Hernandez
2022-09-19 7:37 ` Richard Biener
2022-09-19 8:25 ` Jakub Jelinek
2022-09-19 13:04 ` Aldy Hernandez
2022-09-19 13:06 ` Aldy Hernandez
2022-09-19 13:44 ` Richard Biener
2022-09-20 5:22 ` Aldy Hernandez
2022-09-20 8:26 ` Jakub Jelinek [this message]
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