[Bug tree-optimization/68521] [6.0 regression] ICE on valid code

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68521

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 36832
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36832&action=edit
unrelated(?) patch

Yeah, note that tree-complex.c is structured in a way that exposes SSA name
uses without actually having built the defs...

I've run into this for some unrelated work (not finished) and produced the
attached to fix that.