https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91173
Jeffrey A. Law <law at redhat dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |law at redhat dot com --- Comment #2 from Jeffrey A. Law <law at redhat dot com> --- This is a bug in gen_addr_rtx which doesn't handle the case where the base address is a constant. We end up using the mode of the constant to generate a REG, which of course doesn't work because constants are modeless. I think the fix is as simple as changing a gen_rtx_PLUS to a suitable simplify_gen_binary. I'll spin that. The change in copy propagation is just a trigger, AFAICT this has likely been latent a long time.