glibc fails to build with GCC mainline for SPARC because of the use of
manually-created IFUNCs, which fail the tests of compatibility of
function alias types. This patch changes sparc-ifunc.h to use the
generic __ifunc in defining sparc_libm_ifunc. The generic __ifunc can
use the GCC ifunc attribute when available, so ensuring
type-correctness as well as better debug info than when setting symbol
types in asm statements.
Note that for this to fix the build with GCC mainline the GCC patch
<https://gcc.gnu.org/ml/gcc-patches/2017-09/msg01779.html>, or
building GCC with --enable-gnu-indirect-function, is also needed.
Tested (compilation only) with build-many-glibcs.py (sparc64-linux-gnu
and sparcv9-linux-gnu, with GCC 8 with the above patch, and also with
GCC 7).
* sysdeps/sparc/sparc-ifunc.h [!__ASSEMBLER__] (sparc_libm_ifunc):
Define using __ifunc.