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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/109359] [12/13 Regression] Compile-time rounding of double literal to float is incorrect with -frounding-math
Date: Fri, 14 Apr 2023 09:49:03 +0000	[thread overview]
Message-ID: <bug-109359-4-2dKs58tsd4@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-109359-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109359

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #3)
> I think the fold-const.cc change is right though.
> I wonder if for constant evaluation (constexpr, constinit) we shouldn't
> arrange for those to be evaluated with temporarily -fno-rounding-math, I
> think C uses
> fold_init and its START_FOLD_INIT ... END_FOLD_INIT for this purpose..
> And otherwise perhaps we want dynamic initialization and do the conversion
> at runtime?
> Or disable the -frounding-math for all initializer folding?
> What we emit is definitely wrong,
> Variable which claims to have 8 bytes in size but actually has 16 under the
> hood, with constants in different mode.

We should have ICEd emitting the constant.  And yes, I think -frounding-math
should be disabled for constinit initializer folding (and possibly whether
it is const or not should not depend on -frounding-math).

  parent reply	other threads:[~2023-04-14  9:49 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-31 12:33 [Bug c++/109359] New: " rcopley at gmail dot com
2023-03-31 13:23 ` [Bug c++/109359] [12/13 Regression] " rguenth at gcc dot gnu.org
2023-03-31 13:36 ` jakub at gcc dot gnu.org
2023-03-31 14:23 ` jakub at gcc dot gnu.org
2023-04-14  9:49 ` rguenth at gcc dot gnu.org [this message]
2023-04-14 10:03 ` jakub at gcc dot gnu.org
2023-04-14 10:08 ` rguenth at gcc dot gnu.org
2023-04-14 10:12 ` jakub at gcc dot gnu.org
2023-05-08 12:26 ` [Bug c++/109359] [12/13/14 " rguenth at gcc dot gnu.org
2024-02-05 18:24 ` jason at gcc dot gnu.org
2024-02-05 18:34 ` [Bug c++/109359] [12/13 " jason at gcc dot gnu.org
2024-02-05 18:47 ` jakub at gcc dot gnu.org
2024-02-05 18:55 ` jason at gcc dot gnu.org
2024-02-05 21:35 ` cvs-commit at gcc dot gnu.org
2024-02-05 22:25 ` cvs-commit at gcc dot gnu.org
2024-02-05 22:25 ` cvs-commit at gcc dot gnu.org
2024-02-05 22:26 ` jason at gcc dot gnu.org

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