From: Aldy Hernandez <aldyh@redhat.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: GCC patches <gcc-patches@gcc.gnu.org>,
Andrew MacLeod <amacleod@redhat.com>,
Andrew Pinski <pinskia@gmail.com>
Subject: Re: [PATCH] Add support for floating point endpoints to frange.
Date: Mon, 29 Aug 2022 16:20:16 +0200 [thread overview]
Message-ID: <CAGm3qMXSpa33Y5ie9ujCOLdvtQsioaYehEpQsRX8yJFarZEZdg@mail.gmail.com> (raw)
In-Reply-To: <YwzKe2VrSFAic8+q@tucnak>
On Mon, Aug 29, 2022 at 4:17 PM Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Mon, Aug 29, 2022 at 04:08:58PM +0200, Aldy Hernandez wrote:
> > On Mon, Aug 29, 2022 at 3:55 PM Jakub Jelinek <jakub@redhat.com> wrote:
> > >
> > > On Mon, Aug 29, 2022 at 03:45:33PM +0200, Aldy Hernandez wrote:
> > > > For convenience, singleton_p() returns false for a NAN. IMO, it makes
> > > > the implementation cleaner, but I'm not wed to the idea if someone
> > > > objects.
> > >
> > > If singleton_p() is used to decide whether one can just replace a variable
> > > with singleton range with a constant, then certainly.
> > > If MODE_HAS_SIGNED_ZEROS, zero has 2 representations (-0.0 and 0.0) and
> > > NaNs have lots of different representations (the sign bit is ignored
> > > except for stuff like copysign/signbit, there are qNaNs and sNaNs and
> > > except for the single case how Inf is represented, all other values of the
> > > mantissa mean different representations of NaN). So, unless we track which
> > > exact form of NaN can appear, NaN or any [x, x] range with NaN property
> >
> > Ok that was more or less what I was thinking. And no, we don't keep
> > track of the type of NANs.
> >
> > How does this look?
> >
> > bool
> > frange::singleton_p (tree *result) const
> > {
> > if (m_kind == VR_RANGE && real_identical (&m_min, &m_max))
> > {
> > // If we're honoring signed zeros, fail because we don't know
> > // which zero we have. This avoids propagating the wrong zero.
> > if (HONOR_SIGNED_ZEROS (m_type) && zero_p ())
> > return false;
> >
> > // Return false for any singleton that may be a NAN.
> > if (!get_nan ().no_p ())
> > return false;
>
> Perhaps if (HONOR_NANS (m_type) && !get_nan ().no_p ()) instead?
> Or do you ensure the nan property is never set for -ffinite-math-only?
See followup with Tom downthread.
Sure, I can add the HONOR_NANS, but can we even "see" a NAN in the IL
for -ffinite-math-only? I suppose it's cleaner with HONOR_NANS....
Aldy
next prev parent reply other threads:[~2022-08-29 14:20 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-23 11:42 Aldy Hernandez
2022-08-26 15:55 ` Aldy Hernandez
2022-08-26 17:40 ` Andrew Pinski
2022-08-26 18:11 ` Aldy Hernandez
2022-08-26 18:11 ` Aldy Hernandez
2022-08-26 19:16 ` Aldy Hernandez
2022-08-26 19:44 ` Andrew Pinski
2022-08-29 13:45 ` Aldy Hernandez
2022-08-29 13:54 ` Jakub Jelinek
2022-08-29 14:07 ` Toon Moene
2022-08-29 14:15 ` Aldy Hernandez
2022-08-29 14:30 ` Toon Moene
2022-08-29 14:36 ` Aldy Hernandez
2022-08-29 14:42 ` Toon Moene
2022-08-30 9:27 ` Aldy Hernandez
2022-08-31 15:22 ` Jeff Law
2022-08-31 15:19 ` Jeff Law
2022-08-29 14:08 ` Aldy Hernandez
2022-08-29 14:17 ` Jakub Jelinek
2022-08-29 14:20 ` Aldy Hernandez [this message]
2022-08-29 14:27 ` Jakub Jelinek
2022-08-29 14:30 ` Aldy Hernandez
2022-08-31 15:24 ` Jeff Law
2022-08-30 22:32 ` Joseph Myers
2022-08-31 15:16 ` Jeff Law
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