https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103568
--- Comment #1 from Segher Boessenkool <segher at gcc dot gnu.org> --- Confirmed. This is cheaper in GPRs until we had the lxvrdx insn, which is power10 (ISA 3.1) itself. Wrt dword 1 being zeroed by fp insns. ISA 3.1 has a note saying this was true on all earlier implementations (namely, p7, p8, p9) as well. As far as I know these are in fact the only older implementations of VSX.