[Bug target/127953] missing a constexpr equivalent of __builtinX for _mmX_bslli_X/_mmX_bsrli_X

[gero.peterhoff at gmx dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127953

--- Comment #2 from Gero <gero.peterhoff at gmx dot net> ---
However, shifts using __int128 are not vectorized. But that's exactly the
point.