QEMU emulation of fmadds instruction on powerpc64le is buggy

This bug has been copied automatically from: https://bugs.launchpad.net/qemu/+bug/1912934
Reported by 'Bruno Haible' on 2021-01-24 :

The attached program test-fmadds.c tests the fmadds instruction on
powerpc64le.

Result on real hardware (POWER8E processor):
$ ./a.out ; echo $?
0

Result in Alpine Linux 3.13/powerpcle, emulated by QEMU 5.0.0 on Ubuntu
16.04:
$ ./a.out ; echo $?
32

Result in Debian 8.6.0/ppc64el, emulated by QEMU 2.9.0 on Ubuntu 16.04:
$ ./a.out ; echo $?
32

Through 'nm --dynamic qemu-system-ppc64 | grep fma' I can see that QEMU is
NOT using the fmaf() or fma() function from the host system's libc; this
function is working fine in glibc of the host system (see
https://www.gnu.org/software/gnulib/manual/html_node/fmaf.html ).