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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/102498] [9/10 Regression] Long double constant and non-default rounding mode on x86
Date: Wed, 11 May 2022 06:22:32 +0000 [thread overview]
Message-ID: <bug-102498-4-1ri9wPCwKB@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102498-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102498
--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:8837138d292eb4221a5d5a985d25e487a127539d
commit r9-10102-g8837138d292eb4221a5d5a985d25e487a127539d
Author: Jakub Jelinek <jakub@redhat.com>
Date: Tue Sep 28 13:02:51 2021 +0200
i386: Don't emit fldpi etc. if -frounding-math [PR102498]
i387 has instructions to store some transcedental numbers into the top of
stack. The problem is that what exact bit in the last place one gets for
those depends on the current rounding mode, the CPU knows the number with
slightly higher precision. The compiler assumes rounding to nearest when
comparing them against constants in the IL, but at runtime the rounding
can be different and so some of these depending on rounding mode and the
constant could be 1 ulp higher or smaller than expected.
We only support changing the rounding mode at runtime if the non-default
-frounding-mode option is used, so the following patch just disables
using those constants if that flag is on.
2021-09-28 Jakub Jelinek <jakub@redhat.com>
PR target/102498
* config/i386/i386.c (standard_80387_constant_p): Don't recognize
special 80387 instruction XFmode constants if flag_rounding_math.
* gcc.target/i386/pr102498.c: New test.
(cherry picked from commit 3b7041e8345c2f1030e58620f28e22d64b2c196b)
next prev parent reply other threads:[~2022-05-11 6:22 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-27 14:27 [Bug c/102498] New: wrong output of printf with long double constant and non-default rounding mode zimmerma+gcc at loria dot fr
2021-09-27 15:00 ` [Bug c/102498] wrong output of printf with long double constant (pi) " vincent-gcc at vinc17 dot net
2021-09-27 15:11 ` [Bug target/102498] " jakub at gcc dot gnu.org
2021-09-27 15:20 ` jakub at gcc dot gnu.org
2021-09-27 16:50 ` vincent-gcc at vinc17 dot net
2021-09-27 22:35 ` [Bug target/102498] [9/10/11/12 Regression] Long double constant and non-default rounding mode on x86 pinskia at gcc dot gnu.org
2021-09-28 0:57 ` vincent-gcc at vinc17 dot net
2021-09-28 1:14 ` pinskia at gcc dot gnu.org
2021-09-28 8:17 ` vincent-gcc at vinc17 dot net
2021-09-28 11:03 ` cvs-commit at gcc dot gnu.org
2021-09-28 11:07 ` cvs-commit at gcc dot gnu.org
2021-09-28 11:10 ` [Bug target/102498] [9/10 " jakub at gcc dot gnu.org
2022-05-10 8:20 ` cvs-commit at gcc dot gnu.org
2022-05-10 8:46 ` zimmerma+gcc at loria dot fr
2022-05-10 11:57 ` vincent-gcc at vinc17 dot net
2022-05-10 12:00 ` vincent-gcc at vinc17 dot net
2022-05-11 6:22 ` cvs-commit at gcc dot gnu.org [this message]
2022-05-11 6:36 ` jakub at gcc dot gnu.org
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