From: Florian Weimer <fweimer@redhat.com>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
Joseph Myers <joseph@codesourcery.com>,
"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Cc: nd <nd@arm.com>
Subject: Re: Improving math function wrappers
Date: Thu, 16 Mar 2017 21:22:00 -0000 [thread overview]
Message-ID: <3623011d-1a3a-c499-6b42-1d5506c6a71a@redhat.com> (raw)
In-Reply-To: <AM5PR0802MB261064538EBF55E8B7CF1F7783260@AM5PR0802MB2610.eurprd08.prod.outlook.com>
On 03/16/2017 02:52 PM, Wilco Dijkstra wrote:
> While the wrappers may be bypassed when building with -Ofast, this uses C header
> magic (ie. it doesn't work in languages other than C and C++). Given other languages
> don't even have the concept of errno, C99 doesn't require it, and no application ever
> reads errno, it is inefficient to force the use of the wrappers in almost all cases.
What's the expensive part? Computing what errno value to set, or
obtaining the location of errno?
We have recently removed the PID cache from the TCB. We could store the
errno value there, instead of going through __errno_location. (Code
outside glibc would still use __errno_location, of course.)
Florian
next prev parent reply other threads:[~2017-03-16 21:22 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AM5PR0802MB2610AA7EDC518B39F6D7152683260@AM5PR0802MB2610.eurprd08.prod.outlook.com>
2017-03-16 13:53 ` Wilco Dijkstra
2017-03-16 14:39 ` Joseph Myers
2017-03-16 14:41 ` Joseph Myers
2017-03-16 18:07 ` Szabolcs Nagy
2017-03-16 18:24 ` Joseph Myers
2017-04-04 17:25 ` Szabolcs Nagy
2017-04-04 17:34 ` Joseph Myers
2017-04-07 15:54 ` Szabolcs Nagy
2017-04-04 17:41 ` Zack Weinberg
2017-03-16 21:22 ` Florian Weimer [this message]
2017-03-16 21:36 ` Joseph Myers
2017-03-16 22:49 ` Wilco Dijkstra
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