Re: [Qemu-devel] [PATCH 2/2] target/hppa: prevent trashing of temporary in do_depw_sar()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Sven,

On 9/13/19 12:17 PM, Sven Schnelle wrote:
> nullify_over() calls brcond which destroys all temporaries.
> 
> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> ---
>  target/hppa/translate.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/target/hppa/translate.c b/target/hppa/translate.c
> index b12525d535..c1b2822f60 100644
> --- a/target/hppa/translate.c
> +++ b/target/hppa/translate.c
> @@ -3404,10 +3404,6 @@ static bool do_depw_sar(DisasContext *ctx, unsigned rt, unsigned c,
>      TCGv_reg mask, tmp, shift, dest;
>      unsigned msb = 1U << (len - 1);
>  
> -    if (c) {
> -        nullify_over(ctx);
> -    }
> -
>      dest = dest_gpr(ctx, rt);
>      shift = tcg_temp_new();
>      tmp = tcg_temp_new();
> @@ -3440,11 +3436,17 @@ static bool do_depw_sar(DisasContext *ctx, unsigned rt, unsigned c,
>  
>  static bool trans_depw_sar(DisasContext *ctx, arg_depw_sar *a)
>  {
> +    if (a->c) {
> +        nullify_over(ctx);
> +    }
>      return do_depw_sar(ctx, a->t, a->c, a->nz, a->clen, load_gpr(ctx, a->r));
>  }
>  
>  static bool trans_depwi_sar(DisasContext *ctx, arg_depwi_sar *a)
>  {
> +    if (a->c) {
> +        nullify_over(ctx);
> +    }

I don't see how this patch helps or change anything, isn't it the same?
You clean in the caller rather than the callee.

>      return do_depw_sar(ctx, a->t, a->c, a->nz, a->clen, load_const(ctx, a->i));
>  }
>  
>