From: Qing Zhao <qing.zhao@oracle.com>
To: Richard Biener <richard.guenther@gmail.com>,
Alexander Monakov <amonakov@ispras.ru>
Cc: Jeff Law <jeffreyalaw@gmail.com>, gcc Patches <gcc-patches@gcc.gnu.org>
Subject: Re: Should -ffp-contract=off the default on GCC?
Date: Wed, 22 Mar 2023 15:52:25 +0000 [thread overview]
Message-ID: <E60EA5DB-25AF-42D8-8653-4063A31C3895@oracle.com> (raw)
In-Reply-To: <CAFiYyc2uBxK8qttvWx0M7XwFLj=fH-22XoVuJ7sRxXf=W67xcA@mail.gmail.com>
> On Mar 22, 2023, at 9:57 AM, Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>
> On Wed, Mar 22, 2023 at 1:26 PM Alexander Monakov <amonakov@ispras.ru> wrote:
>>
>>
>> On Wed, 22 Mar 2023, Richard Biener wrote:
>>
>>> I think it's even less realistic to expect users to know the details of
>>> floating-point math. So I doubt any such sentence will be helpful
>>> besides spreading some FUD?
>>
>> I think it's closer to "fundamental notions" rather than "details". For
>> users who bother to read the GCC manual there's a decent chance it wouldn't
>> be for naught.
>>
>> For documentation, I was thinking
>>
>> Together with -fexcess-precision=standard, -ffp-contract=off
>> is necessary to ensure that rounding of intermediate results to precision
>> implied by the source code and the FLT_EVAL_METHOD macro is not
>> omitted by the compiler.
>
> that sounds good to me
Shall we add such clarification to our Gcc13 doc? That should be helpful if we keep the currently default.
Qing
>
>> Alexander
next prev parent reply other threads:[~2023-03-22 15:52 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-16 16:24 Qing Zhao
2023-03-16 16:31 ` Andrew Pinski
2023-03-16 16:38 ` Qing Zhao
2023-03-16 16:53 ` Jakub Jelinek
2023-03-16 18:40 ` Qing Zhao
2023-03-20 22:05 ` Qing Zhao
2023-03-20 22:25 ` Jakub Jelinek
2023-03-21 12:49 ` Qing Zhao
2023-03-21 15:01 ` Qing Zhao
2023-03-21 16:56 ` Paul Koning
2023-03-21 17:00 ` Qing Zhao
2023-03-21 17:59 ` Jeff Law
2023-03-21 18:03 ` Paul Koning
2023-03-21 18:55 ` Toon Moene
2023-03-21 18:12 ` Alexander Monakov
2023-03-21 18:18 ` Jeff Law
2023-03-22 10:13 ` Richard Biener
2023-03-22 12:26 ` Alexander Monakov
2023-03-22 13:57 ` Richard Biener
2023-03-22 15:52 ` Qing Zhao [this message]
2023-03-24 7:12 ` Fangrui Song
2023-03-24 19:42 ` Andrew Pinski
2023-03-31 16:31 ` Qing Zhao
2023-03-21 19:01 ` Qing Zhao
2023-03-21 19:12 ` Jakub Jelinek
2023-03-21 23:28 ` Jeff Law
2023-03-21 23:31 ` Jakub Jelinek
2023-03-21 19:51 ` Jeff Law
2023-03-21 21:08 ` Qing Zhao
2023-03-22 12:33 ` Alexander Monakov
2023-03-22 14:33 ` Qing Zhao
2023-03-27 9:03 Zeson
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