[Bug target/81504] [7/8 Regression] gcc-7 regression: vec_st in loop misoptimized

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81504

--- Comment #9 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
Fixed on trunk so far.  Will commit backport in about a week.