[Bug rtl-optimization/74585] powerpc64: Very poor code generation for homogeneous vector aggregates passed in registers

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=74585

--- Comment #15 from Segher Boessenkool <segher at gcc dot gnu.org> ---
The compiler now seems to assume in earlier passes that parameters and
return values are passed in memory.  This is very sub-optimal, all but the
last passes cannot do much useful work this way.