Re: [Qemu-devel] [PATCH 8/8] tcg: Sanity check goto_tb input

[Aurelien Jarno <aurelien@aurel32.net>]

On Fri, Sep 21, 2012 at 05:18:16PM -0700, Richard Henderson wrote:
> Checking that we don't try for idx != [01] is trivial.  Checking
> that we don't issue more than one of any index requires a tad
> more data and some ifdefs protecting that new variable.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> Cc: Max Filippov <jcmvbkbc@gmail.com>
> ---
>  tcg/tcg-op.h | 11 +++++++++--
>  tcg/tcg.c    |  4 ++++
>  tcg/tcg.h    |  1 +
>  3 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/tcg/tcg-op.h b/tcg/tcg-op.h
> index ecb1ac3..9bfed48 100644
> --- a/tcg/tcg-op.h
> +++ b/tcg/tcg-op.h
> @@ -2275,8 +2275,15 @@ static inline void tcg_gen_exit_tb(tcg_target_long val)
>      tcg_gen_op1i(INDEX_op_exit_tb, val);
>  }
>  
> -static inline void tcg_gen_goto_tb(int idx)
> -{
> +static inline void tcg_gen_goto_tb(unsigned idx)
> +{
> +    /* We only support two chained exits.  */
> +    tcg_debug_assert(idx <= 1);
> +#ifdef CONFIG_DEBUG_TCG
> +    /* Verify that we havn't seen this numbered exit before.  */
> +    tcg_debug_assert((tcg_ctx.goto_tb_issue_mask & (1 << idx)) == 0);
> +    tcg_ctx.goto_tb_issue_mask |= 1 << idx;
> +#endif
>      tcg_gen_op1i(INDEX_op_goto_tb, idx);
>  }
>  
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index bb9c995..a703e1e 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -299,6 +299,10 @@ void tcg_func_start(TCGContext *s)
>      s->nb_labels = 0;
>      s->current_frame_offset = s->frame_start;
>  
> +#ifdef CONFIG_DEBUG_TCG
> +    s->goto_tb_issue_mask = 0;
> +#endif
> +
>      gen_opc_ptr = gen_opc_buf;
>      gen_opparam_ptr = gen_opparam_buf;
>  }
> diff --git a/tcg/tcg.h b/tcg/tcg.h
> index 4501c15..af7464a 100644
> --- a/tcg/tcg.h
> +++ b/tcg/tcg.h
> @@ -390,6 +390,7 @@ struct TCGContext {
>  
>  #ifdef CONFIG_DEBUG_TCG
>      int temps_in_use;
> +    int goto_tb_issue_mask;
>  #endif
>  };
>  

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net