[Bug target/92566] rs6000_preferred_simd_mode isn't very good

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92566

--- Comment #2 from Kewen Lin <linkw at gcc dot gnu.org> ---
Created attachment 47295
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47295&action=edit
Guard V2DImode and V1TImode under VSX and P8VECTOR