[Bug libstdc++/114417] std::experimental::simd is not a POD (by ABI definitions) and is always passed by reference instead of by value

["mkretz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114417

Matthias Kretz (Vir) <mkretz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |mkretz at gcc dot gnu.org

--- Comment #9 from Matthias Kretz (Vir) <mkretz at gcc dot gnu.org> ---
Sorry for not noticing this PR earlier. Yes, this specific behavior of
fixed_size follows a request from the C++ committee for the TS. It is not
mandated by the TS wording, because the C++ spec has no means to require
passing arguments via the stack or registers. That's beyond the abstract
machine. It still asks for that behavior non-normatively, though.

What you want to use instead is std::experimental::simd_abi::deduce_t<T, N>.
That'll give you a not-fixed_size ABI if one exists. And those will likely be
passed via registers (as long as the psABI allows).