https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110304
--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to cqwrteur from comment #13) > See this: > https://godbolt.org/z/eozPahn9G > > > addcarry pattern it recognizes but not subcarry. And see this: https://gcc.gnu.org/pipermail/gcc-patches/2023-June/620821.html I've said that due to reassoc subcarry can't be matched because the different limbs get intermingled too much. And that one should be using the overflow builtins (or now the clang compatible builtins) instead, at least for now. > Also see the pissmeoff2, the instructions GCC generates are very messy. Please carefully read the Code of Conduct that has been announced today. https://gcc.gnu.org/conduct.html
