Re: [PATCH for-6.2 17/34] target/arm: Implement MVE VMLAS

[Richard Henderson]

On 7/13/21 6:37 AM, Peter Maydell wrote:
> Implement the MVE VMLAS insn, which multiplies a vector by a vector
> and adds a scalar.
>
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   target/arm/helper-mve.h    |  8 ++++++++
>   target/arm/mve.decode      |  3 +++
>   target/arm/mve_helper.c    | 31 +++++++++++++++++++++++++++++++
>   target/arm/translate-mve.c |  2 ++
>   4 files changed, 44 insertions(+)
...

> +/* Vector by vector plus scalar */
> +#define DO_VMLAS(D, N, M) ((N) * (D) + (M))
> +
> +DO_2OP_ACC_SCALAR_S(vmlass, DO_VMLAS)
> +DO_2OP_ACC_SCALAR_U(vmlasu, DO_VMLAS)

This is confusing.  The ARM says

# Operations that do not perform
# widening are always unsigned (encoded with U=1),

This instruction does not perform widening, but it then codes on to enumerate the 
signed/unsigned encodings.

I suppose you're matching what's written, so
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~