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From: "xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107608] [13 Regression] Failure on fold-overflow-1.c and pr95115.c
Date: Fri, 27 Jan 2023 07:59:56 +0000	[thread overview]
Message-ID: <bug-107608-4-A0lqXWDp7l@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-107608-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107608

--- Comment #46 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #45)
> (In reply to Xi Ruoyao from comment #44)
> > (In reply to rguenther@suse.de from comment #43)

> > > If the result is unused then no, GCC will happily elide exceptions from
> > > unused computations like Inexact from the statement
> > > 
> > >  1./3.;
> > > 
> > > but this has been done before.  What's new is that GCC can now elide
> > > some uses (in this case the isnan check is the only use)
> > 
> > The should we just change PR95115 to "INVALID" and remove the test case, and
> > fix any regression on Glibc side?
> 
> I think we should adjust the testcase with a volatile like I suggested above
> so we verify that we don't eliminate the computation with a "constant" NaN.

Ok, I'll post a patch.

Glibc already changed the code from Inf/Inf to (x - x) / (x - x) where x is not
a constant, but I'm wandering if the compiler will attempt to optimize out (x -
x) / (x - x) later...  Is it possible to provide a "__builtin_feraiseexcept" so
we'd be able to use it instead of the nasty (x - x) / (x - x) to raise the
exception?

  parent reply	other threads:[~2023-01-27  7:59 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-10  9:47 [Bug tree-optimization/107608] New: [13 Regression] Failure on fold-overflow-1.c jakub at gcc dot gnu.org
2022-11-10  9:49 ` [Bug tree-optimization/107608] " jakub at gcc dot gnu.org
2022-11-10 13:47 ` rguenth at gcc dot gnu.org
2022-11-10 18:13 ` pinskia at gcc dot gnu.org
2022-11-11  7:18 ` pinskia at gcc dot gnu.org
2022-11-13  6:30 ` [Bug tree-optimization/107608] [13 Regression] Failure on fold-overflow-1.c and pr95115.c xry111 at gcc dot gnu.org
2022-11-28 10:06 ` rguenth at gcc dot gnu.org
2022-12-05 13:22 ` aldyh at gcc dot gnu.org
2022-12-05 15:14 ` rguenth at gcc dot gnu.org
2022-12-05 16:30 ` aldyh at gcc dot gnu.org
2022-12-16 13:20 ` jakub at gcc dot gnu.org
2022-12-16 13:32 ` rguenth at gcc dot gnu.org
2023-01-09 15:18 ` aldyh at gcc dot gnu.org
2023-01-10  8:56 ` rguenth at gcc dot gnu.org
2023-01-10  8:58 ` rguenth at gcc dot gnu.org
2023-01-10 10:20 ` aldyh at gcc dot gnu.org
2023-01-10 10:25 ` aldyh at gcc dot gnu.org
2023-01-10 11:00 ` rguenth at gcc dot gnu.org
2023-01-10 11:09 ` jakub at gcc dot gnu.org
2023-01-10 12:08 ` rguenther at suse dot de
2023-01-10 14:14 ` jakub at gcc dot gnu.org
2023-01-10 14:25 ` amacleod at redhat dot com
2023-01-10 14:33 ` aldyh at gcc dot gnu.org
2023-01-10 14:39 ` jakub at gcc dot gnu.org
2023-01-10 14:40 ` aldyh at gcc dot gnu.org
2023-01-10 14:42 ` jakub at gcc dot gnu.org
2023-01-12 11:42 ` aldyh at gcc dot gnu.org
2023-01-12 12:03 ` jakub at gcc dot gnu.org
2023-01-12 12:26 ` xry111 at gcc dot gnu.org
2023-01-13 13:19 ` aldyh at gcc dot gnu.org
2023-01-13 13:25 ` aldyh at gcc dot gnu.org
2023-01-15 15:43 ` cvs-commit at gcc dot gnu.org
2023-01-16 21:38 ` romain.geissler at amadeus dot com
2023-01-16 21:46 ` jakub at gcc dot gnu.org
2023-01-16 21:55 ` romain.geissler at amadeus dot com
2023-01-16 21:58 ` fw at gcc dot gnu.org
2023-01-18 12:26 ` aldyh at gcc dot gnu.org
2023-01-18 12:54 ` jakub at gcc dot gnu.org
2023-01-18 12:56 ` aldyh at gcc dot gnu.org
2023-01-18 13:00 ` rguenth at gcc dot gnu.org
2023-01-18 13:03 ` rguenth at gcc dot gnu.org
2023-01-18 13:05 ` rguenth at gcc dot gnu.org
2023-01-19  1:15 ` xry111 at gcc dot gnu.org
2023-01-19  7:17 ` rguenther at suse dot de
2023-01-26 14:29 ` xry111 at gcc dot gnu.org
2023-01-27  7:35 ` rguenth at gcc dot gnu.org
2023-01-27  7:59 ` xry111 at gcc dot gnu.org [this message]
2023-01-27  9:53 ` rguenther at suse dot de
2023-01-27 10:02 ` xry111 at gcc dot gnu.org
2023-01-27 10:13 ` jakub at gcc dot gnu.org
2023-01-27 11:30 ` rguenther at suse dot de

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