On 2/16/06, Jakub Jelinek <[EMAIL PROTECTED]> 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.
