From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: Lewis Hyatt <lhyatt@gmail.com>
Cc: "François Dumont" <frs.dumont@gmail.com>,
libstdc++ <libstdc++@gcc.gnu.org>,
"Dietmar Kuehl" <dietmar_kuehl@yahoo.com>
Subject: Re: ostream::operator<<() and sputn()
Date: Tue, 11 Jan 2022 01:09:03 +0000 [thread overview]
Message-ID: <CAH6eHdTj_sRH2j=nDqGEF0Mq2jzMMLp5=hnzXHyPcdbUAr70tg@mail.gmail.com> (raw)
In-Reply-To: <CAA_5UQ6FbJedoAj8phxyPjJKVvkikM9zD6ug1kk-fw12fyvDCg@mail.gmail.com>
On Mon, 10 Jan 2022 at 23:18, Lewis Hyatt wrote:
> Thanks a lot for circling back to this. I feel like your change is a
> pure improvement with little downside, so it would be great to have
> it. Let me know please if I should do anything more there.
Leave it with me.
> To me, the whole situation with sputn() is just unfortunate, because I
> think it should not have been specified to always make the virtual
> call to xsputn(), but rather only make it if needed. Then everything
> would work as well as possible. Like after this change to the
> single-char overload, a similar unexpected performance issue will
> affect something like: cout << "a" compared to cout << 'a', where
> now the former will make a virtual call every time and the latter
> won't. libstdc++ could handle the char* overload case as well, but
> then it still would not be permitted to handle a string or
> string_view, so at some level the standard specification is the
> constraint... Seems unlikely it will change though, so I think it
> means that avoiding sputn() wherever permitted will always be an
> avenue towards improving performance.
I think the standard is overspecified, and changing it makes sense. It will
take some time though.
next prev parent reply other threads:[~2022-01-11 1:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 21:26 Lewis Hyatt
2021-07-14 21:30 ` Jonathan Wakely
2021-07-14 21:45 ` Lewis Hyatt
2021-07-15 17:11 ` François Dumont
2022-01-10 16:07 ` Jonathan Wakely
2022-01-10 23:18 ` Lewis Hyatt
2022-01-11 1:09 ` Jonathan Wakely [this message]
2021-07-14 21:54 ` Dietmar Kühl
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