[Bug tree-optimization/125974] Missed optimisation: excessive use of vperm and vshuf with complex type

[mjr19 at cam dot ac.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125974

--- Comment #1 from mjr19 at cam dot ac.uk ---
Looking further, this might not be a bug. -O3 produces the code I would expect,
and -O3 -ffast-math or -Ofast produces the more verbose code. But the more
verbose code has much better ILP. It might not actually be any slower, although
I am still struggling to believe that it is any faster.