Re: [PATCH v2 10/12] target/arm: Optimize MVE VSHLL and VMOVL

[Peter Maydell]

On Mon, 13 Sept 2021 at 15:04, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> On 9/13/21 2:54 AM, Peter Maydell wrote:
> > Optimize the MVE VSHLL insns by using TCG vector ops when possible.
> > This includes the VMOVL insn, which we handle in mve.decode as "VSHLL
> > with zero shift count".
> >
> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> > ---
> > The cases here that I've implemented with ANDI then shift
> > could also be implemented as shift-then-shift. Is one better
> > than another?
>
> I would expect and + shift to be preferred over shift + shift.

OK. (I wasn't sure, because and + shift requires another insn
to assemble the immediate constant, I think.)

-- PMM