https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115876
--- Comment #16 from Jeffrey A. Law <law at gcc dot gnu.org> --- At least part of these are coming from the use-side processing of TImode operations in carry_backpropagate. The right thing to do in that case is just return the mode mask indicating all the chunks are potentially live rather than trying to figure out a narrower mask and triggering undefined behavior in the process. I won't be surprised if there are other cases in the use side processing that are problematic in this regard. They shouldn't impact correctness of transformations, but do need to be fixed to be ub-clean. Anyway, spinning the first fix in this space now...
