[Bug tree-optimization/83887] [8 Regression] [graphite] ICE in verify_dominators, at dominance.c:1184 (error: dominator of 3 should be 21, not 18)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83887

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Not infinite loop but still an invalid non-SESE region...  using
post-dominators for SESE merging looks not sufficient.

Testing patch.