https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98638
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- Fortran lang_decl has struct GTY(()) lang_decl { /* Dummy variables. */ tree saved_descriptor; and that eventually contains _121->r (SSA names which refer to def stmts which refer to BBs). The decl is reachable via an abstract origin. I suppose the saved_descriptor has a tree sharing "issue" with sth gimplified.