https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97653
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> --- This was committed, but with the wrong PR number so didn't get added here: The master branch has been updated by Michael Meissner <meiss...@gcc.gnu.org>: https://gcc.gnu.org/g:9f1a6501994a2d18ec4fe2a6664637f48021b210 commit r11-5728-g9f1a6501994a2d18ec4fe2a6664637f48021b210 Author: Michael Meissner <meiss...@linux.ibm.com> Date: Thu Dec 3 14:50:26 2020 -0500 PowerPC: PR libgcc/97543 and libgcc/97643, fix long double issues If you use a compiler with long double defaulting to 64-bit instead of 128-bit with IBM extended double, you get linker warnings about mis-matches in the gnu attributes for long double (PR libgcc/97543). Even if the compiler is configured to have long double be 64 bit as the default with the configuration option '--without-long-double-128' you get the warnings. You also get the same issues if you use a compiler with long double defaulting to IEEE 128-bit instead of IBM extended double (PR libgcc/97643). The issue is the way libgcc.a/libgcc.so is built. Right now when building libgcc under Linux, the long double size is set to 128-bits when building libgcc. However, the gnu attributes are set, leading to the warnings. One feature of the current GNU attribute implementation is if you have a shared library (such as libgcc_s.so), the GNU attributes for the shared library is an inclusive OR of all of the objects within the library. This means if any object file that uses the -mlong-double-128 option and uses long double, the GNU attributes for the library will indicate that it uses 128-bit IBM long doubles. If you have a static library, you will get the warning only if you actually reference an object file with the attribute set. This patch does two things: 1) All of the object files that support IBM 128-bit long doubles explicitly set the ABI to IBM extended double. 2) I turned off GNU attributes for building the shared library or for building the IBM 128-bit long double support. libgcc/ 2020-12-03 Michael Meissner <meiss...@linux.ibm.com> PR libgcc/97543 PR libgcc/97643 * config/rs6000/t-linux (IBM128_STATIC_OBJS): New make variable. (IBM128_SHARED_OBJS): New make variable. (IBM128_OBJS): New make variable. Set all objects to use the explicit IBM format, and disable gnu attributes. (IBM128_CFLAGS): New make variable. (gcc_s_compile): Add -mno-gnu-attribute to all shared library modules.
