Re: [Qemu-devel] [PATCH] tcg: optimize gen_extr_i64_i32()

[Richard Henderson]

On 05/12/2017 05:29 PM, Philippe Mathieu-Daudé wrote:
> Inspired by Richard Henderson comment:
>
>      http://lists.nongnu.org/archive/html/qemu-devel/2017-05/msg02277.html
>
> Patch applied mechanically with this coccinelle semantic patch:
>
>      @@
>      expression lo, hi,arg;
>      @@
>      -tcg_gen_extrl_i64_i32(lo, arg);
>      -tcg_gen_extrh_i64_i32(hi, arg);
>      +tcg_gen_extr_i64_i32(lo, hi, arg);
>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>   tcg/tcg-op.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
> index 6b1f41500c..f3d556c21a 100644
> --- a/tcg/tcg-op.c
> +++ b/tcg/tcg-op.c
> @@ -2562,8 +2562,7 @@ void tcg_gen_extr_i64_i32(TCGv_i32 lo, TCGv_i32 hi, 
> TCGv_i64 arg)
>           tcg_gen_mov_i32(lo, TCGV_LOW(arg));
>           tcg_gen_mov_i32(hi, TCGV_HIGH(arg));
>       } else {
> -        tcg_gen_extrl_i64_i32(lo, arg);
> -        tcg_gen_extrh_i64_i32(hi, arg);
> +        tcg_gen_extr_i64_i32(lo, hi, arg);

You've just created an instance of infinite self-recursion.


r~