Re: [Qemu-devel] [PATCH 2/2] PPC: e500: Merge 32 and 64 bit SPE emulation

[Richard Henderson <rth@twiddle.net>]

On 06/04/2014 02:09 PM, Alexander Graf wrote:
> @@ -9030,13 +8820,10 @@ static inline void gen_evmwumi(DisasContext *ctx)
>      t1 = tcg_temp_new_i64();
>  
>      /* t0 := rA; t1 := rB */
> -#if defined(TARGET_PPC64)
> -    tcg_gen_ext32u_tl(t0, cpu_gpr[rA(ctx->opcode)]);
> -    tcg_gen_ext32u_tl(t1, cpu_gpr[rB(ctx->opcode)]);
> -#else
>      tcg_gen_extu_tl_i64(t0, cpu_gpr[rA(ctx->opcode)]);
> +    tcg_gen_ext32u_i64(t0, t0);

Better in one step:

 tcg_gen_ext32u_i64(t0, cpu_gpr[rA(ctx->opcode)]);

> @@ -9112,13 +8899,10 @@ static inline void gen_evmwsmi(DisasContext *ctx)
>      t1 = tcg_temp_new_i64();
>  
>      /* t0 := rA; t1 := rB */
> +    tcg_gen_extu_tl_i64(t0, cpu_gpr[rA(ctx->opcode)]);
> +    tcg_gen_ext32s_i64(t0, t0);
> +    tcg_gen_extu_tl_i64(t1, cpu_gpr[rB(ctx->opcode)]);
> +    tcg_gen_ext32s_i64(t1, t1);

Similarly.

Although I do wonder about using the actual 32-bit widening multiply
primitives: tcg_gen_mulu2_i32 / tcg_gen_muls2_i32.

I suspect the optimizer would clean up the unsigned version, but it hasn't got
a chance with the signed version.

Otherwise, it looks ok.



r~