From: "Koning, Paul" <Paul.Koning@dell.com>
To: Jonathan Wakely <jwakely@redhat.com>
Cc: libstdc++ <libstdc++@gcc.gnu.org>, GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [committed] libstdc++: Support VAX floats in std::strong_order
Date: Thu, 10 Mar 2022 17:46:12 +0000 [thread overview]
Message-ID: <0CD543BD-370B-431B-ABD0-414B9B7982FF@dell.com> (raw)
In-Reply-To: <CACb0b4k3WqZPTWNUCdCb-V0aNGQsGvF5TJkKSdM733jNAdkgSA@mail.gmail.com>
> On Mar 10, 2022, at 9:27 AM, Jonathan Wakely via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>
> On Thu, 10 Mar 2022 at 12:16, Jonathan Wakely wrote:
>>
>> On Thu, 10 Mar 2022 at 11:53, Jonathan Wakely via Libstdc++
>> <libstdc++@gcc.gnu.org> wrote:
>>>
>>> Tested x86_64-linux, and basic soundness check on vax-dec-netbsdelf.
>>
>> But apparently not enough of a soundness check, because
>> isnan(__builtin_nan("")) is true for VAX, so GCC seems to have a NaN
>> pattern, despite what I read online about the format.
VAX float has signalling NaN, but not a non-signalling NaN nor an Inf. See the VAX architecture manual. Signalling NaN (called "reserved operand") is encoded as sign=1 and exponent=0.
paul
prev parent reply other threads:[~2022-03-10 17:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-10 11:51 Jonathan Wakely
2022-03-10 12:16 ` Jonathan Wakely
2022-03-10 14:27 ` Jonathan Wakely
2022-03-10 17:46 ` Koning, Paul [this message]
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