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From: Richard Guenther <richard.guenther@gmail.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Francois-Xavier Coudert <fxcoudert@gmail.com>,
	 	gfortran <fortran@gcc.gnu.org>,
	GCC Development <gcc@gcc.gnu.org>
Subject: Re: gfortran and -mlong-double-128
Date: Thu, 16 Feb 2006 15:17:00 -0000	[thread overview]
Message-ID: <84fc9c000602160715h6a68ddb0nd87054722a46777d@mail.gmail.com> (raw)
In-Reply-To: <20060216141138.GO4625@sunsite.mff.cuni.cz>

On 2/16/06, Jakub Jelinek <jakub@redhat.com> wrote:
> On Thu, Feb 16, 2006 at 01:57:39PM +0100, Fran?ois-Xavier Coudert wrote:
> > > I guess libgfortran has configury to figure out if kind=16 is available?
> >
> > Yes.
> >
> > > If so then libgfortran should be built with -mlong-double-128, as this
> > > should only add extra symbols that do not conflict with kind=4 and kind=8
> > > ones.
> >
> > Hum, that has to be done early in the configury (before all
> > autodetection). Do you think it's better suited at the beginning of
> > libgfortran/configure.ac (a special test, to see if -mlong-double-128
> > is available, and if it is add it to CFLAGS), or should it be done in
> > an upper level (and here is the limit of my understanding of the build
> > mechanism)?
>
> That will not work.  It is not enough if GCC supports -mlong-double-128
> switch, you also need runtime library support for that.
> So the check needs to be something like
> http://gcc.gnu.org/ml/gcc-patches/2006-02/msg01075.html
> (still not reviewed :( ).  If you configure gcc with --with-long-double-128
> (what I'm using e.g. on redhat/gcc-4_1-branch now for
> {ppc*,s390*,sparc,alpha}-*-linux*), then libgfortran is automatically built
> with -mlong-double-128 and can cope with both -mlong-double-128 and
> -mlong-double-64 code.  libstdc++.so will only support both
> -mlong-double-{64,128} if it is built with -mlong-double-128, so it is in
> the same boat as libgfortran.
> Not sure if it makes any sense to detect the presence of glibc 2.4+ and
> build libstdc++-v3/libgfortran with -mlong-double-128 even if configured
> with --without-long-double-128.

Well, fortran is special here compared to libstdc++-v3, because we do not
change its ABI by -mlong-double-128 but only add kind=16 intrinsics support.
So it makes sense to build libgfortran with support for kind=16 if glibc support
is there, regardless of the default setting for long-double.

Richard.

  reply	other threads:[~2006-02-16 15:17 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-16 11:09 François-Xavier Coudert
2006-02-16 12:50 ` Richard Guenther
2006-02-16 12:57   ` François-Xavier Coudert
2006-02-16 14:11     ` Jakub Jelinek
2006-02-16 15:17       ` Richard Guenther [this message]
2006-02-16 15:04 ` Paul Brook
2006-02-16 15:14   ` François-Xavier Coudert
2006-02-16 15:17     ` Paul Brook
2006-02-16 15:19   ` Richard Guenther
2006-02-16 15:24     ` Andrew Pinski
2006-02-16 15:28     ` Paul Brook
2006-02-16 15:48       ` Jakub Jelinek

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