Re: [Qemu-devel] [PATCH 2/3] target/mips: Add emulation of MMI instruction PCPYLD

[Richard Henderson]

On 2/25/19 8:10 AM, Mateja Marjanovic wrote:
> +    if (rd == 0) {
> +        /* nop */
> +    } else if ((rt == 0) && (rs == 0)) {
> +        tcg_gen_movi_i64(cpu_gpr[rt], 0);
> +        tcg_gen_movi_i64(cpu_mmr[rt], 0);
> +    } else if (rt == 0) {
> +        tcg_gen_movi_i64(cpu_gpr[rd], 0);
> +        tcg_gen_mov_i64(cpu_mmr[rd], cpu_gpr[rs]);
> +    } else if (rs == 0) {
> +        tcg_gen_mov_i64(cpu_gpr[rd], cpu_gpr[rt]);
> +        tcg_gen_movi_i64(cpu_mmr[rd], 0);
> +    } else {
> +        tcg_gen_mov_i64(cpu_gpr[rd], cpu_gpr[rt]);
> +        tcg_gen_mov_i64(cpu_mmr[rd], cpu_gpr[rs]);
> +    }

You should avoid multiplying the cases this way.
The same results can be had with

  if (rd != 0) {
      gen_load_gpr(cpu_gpr[rd], rt);
      gen_load_gpr(cpu_mmr[rd], rs);
  }


r~