Re: [PATCH v2 28/34] target/arm: Split gvec_fmla_idx_* for fmls and ah_fmls

[Peter Maydell <peter.maydell@linaro.org>]

On Wed, 29 Jan 2025 at 01:39, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Split negation cases out of gvec_fmla, creating 6 new helpers.
> We no longer pass 'neg' as a bit in simd_data.
>
> Handle FPCR.AH=0 via xor and FPCR.AH=1 via muladd flags.

>  static bool do_fmla_vector_idx(DisasContext *s, arg_qrrx_e *a, bool neg)
>  {
> -    static gen_helper_gvec_4_ptr * const fns[3] = {
> -        gen_helper_gvec_fmla_idx_h,
> -        gen_helper_gvec_fmla_idx_s,
> -        gen_helper_gvec_fmla_idx_d,
> +    static gen_helper_gvec_4_ptr * const fns[3][3] = {
> +        { gen_helper_gvec_fmla_idx_h,
> +          gen_helper_gvec_fmla_idx_s,
> +          gen_helper_gvec_fmla_idx_d },
> +        { gen_helper_gvec_fmls_idx_h,
> +          gen_helper_gvec_fmls_idx_s,
> +          gen_helper_gvec_fmls_idx_d },
> +        { gen_helper_gvec_ah_fmls_idx_h,
> +          gen_helper_gvec_ah_fmls_idx_s,
> +          gen_helper_gvec_ah_fmls_idx_d },
>      };
>      MemOp esz = a->esz;
>      int check = fp_access_check_vector_hsd(s, a->q, esz);
> @@ -6756,8 +6762,7 @@ static bool do_fmla_vector_idx(DisasContext *s, arg_qrrx_e *a, bool neg)
>
>      gen_gvec_op4_fpst(s, a->q, a->rd, a->rn, a->rm, a->rd,
>                        esz == MO_16 ? FPST_A64_F16 : FPST_A64,
> -                      (s->fpcr_ah << 5) | (a->idx << 1) | neg,
> -                      fns[esz - 1]);
> +                      a->idx, fns[esz - 1][neg ? 1 + s->fpcr_ah : 0]);

The indexes into fns[][] here are the wrong way around, so
if you try to do a FMLA on a double it hands you back
gen_helper_gvec_ah_fmls_idx_h ...

thanks
-- PMM