[Bug tree-optimization/91573] Vectorization failure for a loop to do multiply-add because SLP loads unnecessarily require permutation

[hliu at amperecomputing dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91573

--- Comment #5 from Hao Liu <hliu at amperecomputing dot com> ---
Great. It seems really a SLP issue.

I've learnt a lot about vectorization, dump info and -march. Thanks for your
help.