https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100767
--- Comment #6 from Gabriel Marcano <gabemarcano at yahoo dot com> --- I was the one that originally reported the issue on gcc-help, and I can confirm that with the patch the segfault is no longer happening. I do appear to have found a different bug (undefined references to libc symbols only when using -flto), but I am no longer seeing an ICE from lto1.
