https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80925
--- Comment #9 from rdapp at linux dot vnet.ibm.com ---
I built --with-cpu=power7 and still see TARGET_EFFICIENT_UNALIGNED_VSX == true
in the backend which causes unaligned stores to have costs of 1. On my power7
system, TARGET_EFFICIENT_UNALIGNED_VSX is never true.
I stepped through rs6000_override_internal and TARGET_EFFICIENT_UNALIGNED_VSX
is properly unset via the options defined by --with-cpu=power7 (or power6).
Afterwards, however, it is overwritten again by TARGET_P8_VECTOR which, in
turn, is set automatically by the vector test suite depending on the current
CPU:
[...]
} elseif [check_p8vector_hw_available] {
lappend DEFAULT_VECTCFLAGS "-mpower8-vector"
Therefore, whenever the vector tests are run on a power8 CPU,
TARGET_EFFICIENT_UNALIGNED_VSX = 1, no matter the --with-cpu. This would also
explain why I didn't see the fails on my machine, all vect tests are only
called with -maltivec which doesn't override TARGET_EFFICIENT_UNALIGNED_VSX.
So, the way the vect test suite is currently set up, this is kind of expected.
