https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114332
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Given that the x86-64 psABI says:
\item The value of the unused bits beyond the width of the
\texttt{_BitInt(N)} value but within the size of the
\texttt{_BitInt(N)} are unspecified when stored in memory or register.
and that doesn't apply just to N > 64, but also smaller ones, but internally
GCC sign or zero extends only when reading from memory or VAR_DECLs etc., I
think we need to EXTEND_BITINT also the call return values.
