https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116104
--- Comment #5 from Jeffrey A. Law <law at gcc dot gnu.org> --- Given the relatively unstructured nature of RTL and the error message, this is almost certainly a bug in ext-dce. I should have noted that when I assigned the issue to myself. I've been able to trip it with 20000629-1.c. I don't expect it'll be hard to fix at all. Thanks.