Re: [Qemu-devel] [PATCH v6 24/25] target/ppc: Use gen_io_start/end around DARN

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, May 10, 2019 at 10:30:48AM -0700, Richard Henderson wrote:
> Generating a random number counts as I/O, as it cannot be
> replayed and produce the same results.
> 
> Cc: David Gibson <david@gibson.dropbear.id.au>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Acked-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  target/ppc/translate.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index 8d08625c33..76628df6dd 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -1847,13 +1847,22 @@ static void gen_darn(DisasContext *ctx)
>  {
>      int l = L(ctx->opcode);
>  
> -    if (l == 0) {
> -        gen_helper_darn32(cpu_gpr[rD(ctx->opcode)]);
> -    } else if (l <= 2) {
> -        /* Return 64-bit random for both CRN and RRN */
> -        gen_helper_darn64(cpu_gpr[rD(ctx->opcode)]);
> -    } else {
> +    if (l > 2) {
>          tcg_gen_movi_i64(cpu_gpr[rD(ctx->opcode)], -1);
> +    } else {
> +        if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
> +            gen_io_start();
> +        }
> +        if (l == 0) {
> +            gen_helper_darn32(cpu_gpr[rD(ctx->opcode)]);
> +        } else {
> +            /* Return 64-bit random for both CRN and RRN */
> +            gen_helper_darn64(cpu_gpr[rD(ctx->opcode)]);
> +        }
> +        if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
> +            gen_io_end();
> +            gen_stop_exception(ctx);
> +        }
>      }
>  }
>  #endif

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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