Re: [RFC PATCH v2 18/44] target/loongarch: Implement vsat

[Richard Henderson]

On 3/27/23 20:06, Song Gao wrote:
> +static void gen_vsat_s(unsigned vece, TCGv_vec t, TCGv_vec a, int64_t imm)
> +{
> +    TCGv_vec t1;
> +    int64_t max  = (1l << imm) - 1;

This needed 1ull, but better to just use

    max = MAKE_64BIT_MASK(0, imm - 1);

> +    int64_t min =  ~max;

Extra space.

> +    t1 = tcg_temp_new_vec_matching(t);
> +    tcg_gen_dupi_vec(vece, t, min);
> +    tcg_gen_smax_vec(vece, t, a, t);

Use tcg_constant_vec_matching(t, vece, min) instead of dupi.
Three instances.

> +    tcg_gen_dupi_vec(vece, t1, max);
> +    tcg_gen_smin_vec(vece, t, t, t1);
> +}
> +
> +static void do_vsat_s(unsigned vece, uint32_t vd_ofs, uint32_t vj_ofs,
> +                      int64_t imm, uint32_t oprsz, uint32_t maxsz)
> +{
> +    static const TCGOpcode vecop_list[] = {
> +        INDEX_op_smax_vec, INDEX_op_smin_vec, 0
> +        };
> +    static const GVecGen2i op[4] = {
> +        {
> +            .fniv = gen_vsat_s,
> +            .fnoi = gen_helper_vsat_b,
> +            .opt_opc = vecop_list,
> +            .vece = MO_8
> +        },
> +        {
> +            .fniv = gen_vsat_s,
> +            .fnoi = gen_helper_vsat_h,
> +            .opt_opc = vecop_list,
> +            .vece = MO_16
> +        },
> +        {
> +            .fniv = gen_vsat_s,
> +            .fnoi = gen_helper_vsat_w,
> +            .opt_opc = vecop_list,
> +            .vece = MO_32
> +        },
> +        {
> +            .fniv = gen_vsat_s,
> +            .fnoi = gen_helper_vsat_d,
> +            .opt_opc = vecop_list,
> +            .vece = MO_64
> +        },
> +    };
> +
> +    tcg_gen_gvec_2i(vd_ofs, vj_ofs, oprsz, maxsz, imm, &op[vece]);

Better to expand imm to max here, rather than both inside gen_vsat_s and the runtime 
do_vsats_*.

Likewise for the unsigned versions.


r~