Re: [PATCH] target/mips: Fix loongson multimedia condition instructions

[Richard Henderson]

On 3/20/20 9:56 PM, Jiaxun Yang wrote:
>      case OPC_SLE_CP2:
> -        /*
> -         * ??? Document is unclear: Set FCC[CC].  Does that mean the
> -         * FD field is the CC field?
> -         */
> +        cond = TCG_COND_LE;
> +    do_cc_cond:
> +        {
> +            int cc = (ctx->opcode >> 8) & 0x7;
> +            lab = gen_new_label();
> +            tcg_gen_ori_i32(fpu_fcr31, fpu_fcr31, 1 << get_fp_bit(cc));
> +            tcg_gen_brcond_i64(cond, t0, t1, lab);
> +            tcg_gen_xori_i32(fpu_fcr31, fpu_fcr31, 1 << get_fp_bit(cc));
> +            gen_set_label(lab);
> +        }
> +        goto no_rd;
> +        break;

There is no need for a branch here.  This is a deposit operation.

    TCGv_i64 t64 = tcg_temp_new_i64();
    TCGv_i32 t32 = tcg_temp_new_i32();

    tcg_gen_setcond_i64(cond, t64, t0, t1);
    tcg_gen_extrl_i64_i32(t32, t64);
    tcg_gen_deposit_i32(cpu_fcr31, cpu_fcr31, t32,
                        get_fp_bit(cc), 1);

    tcg_temp_free_i32(t32);
    tcg_temp_free_i64(t64);


r~