[PATCH 4/4] x86: provide a 128-bit VBROADCASTSD pseudo

[H.J. Lu]

On Fri, Jun 16, 2023 at 12:32 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> VBROADCASTSD not supporting 128-bit destinations in any of their AVX,
> AVX2, or AVX512F incarnations is presumably because of VMOVDDUP
> precisely supporting this very operation. (It is therefore different
> from e.g. VPBROADCASTQ, which has no exact equivalent.) Still its
> absence has led to people using VPBROADCASTQ as substitution; this could
> have been avoided if such a pseudo had been supported from the very
> beginning.
>
> Note that the pseudos try to match what the real instructions would have
> used as closely as possible, i.e. VexW0 instead of VexWIG for the AVX
> and AVX2 forms as well as AVX2 in the first place for the register
> source form.
> ---
> For being the first example of us supplying such, this is partly RFC. On
> top of that a question is also whether to indeed have split AVX/AVX2
> templates, when in principle one (allowing for both memory and register
> source) could do.
>

I don't think assembler should invent such instructions.

-- 
H.J.