I've played with some patches to PowerPC to set the defaults for fortran. But without doing a full rebuild like you would do with a new distribution, I think it will be problematical, unless you build everything with the default long double set to IEEE 128-bit.
First off all, libquadmath is currently built on Linux 64-bit systems. I never removed building libquadmath once we got the official glibc 2.34 support So to go in more detail of what I've tried. I added an undocumented switch -mfortran that says set the defaults for Fortran. This switch would be used to build libgfortran, and also set with TARGET_F951_OPTIONS for all Fortran invocations. I tried to switch to float128_type_node instead of long_double_type_node. I ran into problems with gimplify in that it could not do a conversion from _Float128 to float. I suspect I didn't actually use the right type. I then went to patches where -mfortran silently switches the long double type to IEEE 128-bit. There you get into various compatibility issues where the linker complains that you are calling between the different long double types. For instance because we are still building libquadmath, libquadmath is marked as having long double being IBM 128-bit, but it is called from Fortran modules that have long double being IEEE 128-bit. I then did a build supressing building libquadmath since I was using LE with glibc 2.34, and I got much further. This time instead of a lot of failures, I got 29 failures, due to libgfortran still being marked as IBM long double and the fortran modules are marked as IEEE long double. Right now, the only way to avoid these things is to build the entire toolchain defaulting to IEEE 128-bit. -- Michael Meissner, IBM PO Box 98, Ayer, Massachusetts, USA, 01432 email: meiss...@linux.ibm.com
