https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46942
--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Florian Weimer from comment #11) > The ABI document was updated: > > Clarify the unspecified nature of excess bits in INTEGER type arguments > <https://gitlab.com/x86-psABIs/x86-64-ABI/-/commit/ > e1ce098331da5dbd66e1ffc74162380bcc213236> > > The ABI did not previously say that the caller needs to sign-extended or > zero-extend, which means that the callee has to extend. As far as I can see, > both GCC and Clang generate code in some cases that assumes the callee > extends. I'm not aware of any cases where GCC does assume that on x86_64. As mentioned in #c0, often we extend both on the caller and callee side, on the caller side it is just our problem doing something that doesn't have to be done (but guess often is faster that way).
