[Bug target/99293] Built-in vec_splat generates sub-optimal code for -mcpu=power10

[meissner at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99293

--- Comment #3 from Michael Meissner <meissner at gcc dot gnu.org> ---
Created attachment 50947
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50947&action=edit
Proposed patch