From: Rich Felker <dalias@libc.org>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Jeff King <peff@peff.net>, git@vger.kernel.org, musl@lists.openwall.com
Subject: Re: [musl] Re: Regression: git no longer works with musl libc's regex impl
Date: Tue, 4 Oct 2016 13:39:26 -0400 [thread overview]
Message-ID: <20161004173926.GA19318@brightrain.aerifal.cx> (raw)
In-Reply-To: <alpine.DEB.2.20.1610041802310.35196@virtualbox>
On Tue, Oct 04, 2016 at 06:08:33PM +0200, Johannes Schindelin wrote:
> Hi Rich,
>
> On Tue, 4 Oct 2016, Rich Felker wrote:
>
> > On Tue, Oct 04, 2016 at 11:27:22AM -0400, Jeff King wrote:
> > > On Tue, Oct 04, 2016 at 11:08:48AM -0400, Rich Felker wrote:
> > >
> > > > 1. is nonzero mod page size, it just works; the remainder of the last
> > > > page reads as zero bytes when mmapped.
> > >
> > > Is that a portable assumption?
> >
> > Yes.
>
> No, it is not. You quote POSIX, but the matter of the fact is that we use
> a subset of POSIX in order to be able to keep things running on Windows.
>
> And quite honestly, there are lots of reasons to keep things running on
> Windows, and even to favor Windows support over musl support. Over four
> million reasons: the Git for Windows users.
>
> So rather than getting into an ideological discussion about "broken"
> systems, it would be good to keep things practical, realizing that those
> users make up a very real chunk of all of Git's users.
>
> As to making NO_REGEX conditional on REG_STARTEND: you are talking about
> apples and oranges here. NO_REGEX is a Makefile flag, while REG_STARTEND
> is a C preprocessor macro.
It seems like you could just always compile the source file, and just
have it all inside #if defined(NO_REGEX) || !defined(REG_STARTEND) or
similar.
> And lastly, the best alternative would be to teach musl about
> REG_STARTEND, as it is rather useful a feature.
Maybe, but it seems fundamentally costly to support -- it's extra
state in the inner loops that imposes costly spill/reload on archs
with too few registers (x86). I'll look at doing this when we
overhaul/replace the regex implementation, and I'm happy to do some
performance-regression tests for adding it now if someone has a simple
patch (as was mentioned on the musl list).
Rich
next prev parent reply other threads:[~2016-10-04 17:39 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-04 15:08 Regression: git no longer works with musl libc's regex impl Rich Felker
2016-10-04 15:27 ` Jeff King
2016-10-04 15:40 ` Rich Felker
2016-10-04 16:08 ` Johannes Schindelin
2016-10-04 16:11 ` Rich Felker
2016-10-04 17:16 ` Johannes Schindelin
2016-10-04 18:00 ` Ray Donnelly
2016-10-04 17:39 ` Rich Felker [this message]
2016-10-05 11:17 ` [musl] " Johannes Schindelin
2016-10-05 13:01 ` Szabolcs Nagy
2016-10-05 13:15 ` Rich Felker
2016-10-04 22:06 ` James B
2016-10-04 22:33 ` Rich Felker
2016-10-04 22:48 ` Junio C Hamano
2016-10-05 13:11 ` Jakub Narębski
2016-10-05 16:15 ` [musl] " Rich Felker
2016-10-05 10:41 ` Johannes Schindelin
2016-10-05 11:59 ` James B
2016-10-05 16:11 ` Jeff King
2016-10-05 16:27 ` Rich Felker
2016-10-06 10:44 ` Johannes Schindelin
2016-10-06 19:18 ` Ævar Arnfjörð Bjarmason
2016-10-06 19:23 ` Jeff King
2016-10-06 19:25 ` Rich Felker
2016-10-06 19:28 ` Jeff King
2016-10-06 22:42 ` Ramsay Jones
2016-10-07 11:30 ` Jakub Narębski
2016-10-04 16:01 ` Johannes Schindelin
-- strict thread matches above, loose matches on Subject: below --
2016-10-05 3:00 [musl] " writeonce
2016-10-05 10:49 ` Johannes Schindelin
2016-10-05 16:37 writeonce
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