[Bug rtl-optimization/65235] [4.8/4.9/5 Regression] Simplifying vec_select of vec_concat miscompiles when first element of vec_concat is const_int

[ktkachov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65235

--- Comment #6 from ktkachov at gcc dot gnu.org ---

> Hmmm... fine line, but maybe this isn't a regression?

I guess it isn't a regression in the release branches, but it is wrong-code