Re: [RFC PATCH v2 4/4] target/avr/translate: Fix SBRC/SBRS instructions

[Richard Henderson]

On 7/7/20 12:00 AM, Philippe Mathieu-Daudé wrote:
> @@ -1385,7 +1385,7 @@ static bool trans_SBRC(DisasContext *ctx, arg_SBRC *a)
>  {
>      TCGv Rr = cpu_r[a->rr];
>  
> -    ctx->skip_cond = TCG_COND_EQ;
> +    ctx->skip_cond = TCG_COND_NE;
>      ctx->skip_var0 = tcg_temp_new();
>      ctx->free_skip_var0 = true;

This is wrong.  The next line is

>     tcg_gen_andi_tl(ctx->skip_var0, Rr, 1 << a->bit);

So we compute "var = R & bit", which should be zero for "Skip if Bit in
Register Clear".  Thus "var EQ 0" is the correct test.


> @@ -1401,7 +1401,7 @@ static bool trans_SBRS(DisasContext *ctx, arg_SBRS *a)
>  {
>      TCGv Rr = cpu_r[a->rr];
>  
> -    ctx->skip_cond = TCG_COND_NE;
> +    ctx->skip_cond = TCG_COND_EQ;
>      ctx->skip_var0 = tcg_temp_new();
>      ctx->free_skip_var0 = true;

Similarly this is "var NE 0".


r~