[Bug target/104673] powerpc e500mc Error: unrecognized opcode: `isel'

[judge.packham at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104673

--- Comment #2 from Chris Packham <judge.packham at gmail dot com> ---
GCC configure line is

$ /home/ctng/crosstool-ng/.build/powerpc-unknown-linux-gnu/src/gcc/configure
--build=x86_64-build_pc-linux-gnu --host=x86_64-build_pc-linux-gnu
--target=powerpc-unknown-linux-gnu
--prefix=/home/ctng/x-tools/powerpc-unknown-linux-gnu
--exec_prefix=/home/ctng/x-tools/powerpc-unknown-linux-gnu
--with-sysroot=/home/ctng/x-tools/powerpc-unknown-linux-gnu/powerpc-unknown-linux-gnu/sysroot
--enable-languages=c,c++ --with-cpu=e500mc --with-pkgversion=crosstool-NG
1.24.0.548_0e1989a --enable-__cxa_atexit --disable-libmudflap --disable-libgomp
--disable-libssp --disable-libquadmath --disable-libquadmath-support
--disable-libsanitizer --disable-libmpx --disable-libstdcxx-verbose
--with-gmp=/home/ctng/crosstool-ng/.build/powerpc-unknown-linux-gnu/buildtools
--with-mpfr=/home/ctng/crosstool-ng/.build/powerpc-unknown-linux-gnu/buildtools
--with-mpc=/home/ctng/crosstool-ng/.build/powerpc-unknown-linux-gnu/buildtools
--with-isl=/home/ctng/crosstool-ng/.build/powerpc-unknown-linux-gnu/buildtools
--enable-lto --enable-threads=posix --enable-target-optspace --enable-plugin
--disable-nls --disable-multilib
--with-local-prefix=/home/ctng/x-tools/powerpc-unknown-linux-gnu/powerpc-unknown-linux-gnu/sysroot
--enable-long-long

Invocation is

$ powerpc-unknown-linux-gnu-gcc -mcpu=e500mc -O2 -c testcase.c -S -o testcase.S

The original error occurred when building glibc. I've yet to produce a testcase
that triggers gcc to emit the isel instruction but you can see the .machine
directive doesn't match up with -mcpu or what gets passed to gas.