[Bug tree-optimization/116842] [15 Regression] ICE definition in block follows the use since r15-3734

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116842

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's another case of "invariant" masked scheduling.  Not sure why the
workaround in SLP scheduling triggers here, investigating.