[Bug middle-end/90796] [8/9/10 Regression] GCC: O2 vs O3 output differs on simple test

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90796

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, the CFG looks like unroll-and-jam attempts to do versioning/peeling
but forgets the tail loop is executed at least once?