[Bug target/124804] [16 Regression] Possible openblas miscompilation since r16-1782

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124804

--- Comment #26 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Unfortunately, right now there are no hooks that could choose to change
simplify_subreg_regno behavior just for the subregs of OOmode/XOmode VSX
registers and not other multireg regs, all the target can do is define
REG_WORDS_BIG_ENDIAN perhaps differently from WORDS_BIG_ENDIAN so that the reg
subregs could follow the memory order.

Anyway, will defer this PR to somebody knowledgeable about PowerPC.