https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104869
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I've tried to figure out where the former (GCC 10) all_uses_available_at checking has gone into (i.e. where we actually check that the propagation is possible, that something doesn't overwrite or clobber the src from the def_insn in between the def_insn and use_insn), but I can't find it, must be hidden somewhere. Richard, could you please have a look or at least hint at where to look for it?
