Re: [Qemu-devel] [PATCH 01/18] tcg: add support for 128bit vector type

[Richard Henderson]

On 01/19/2017 08:54 AM, Kirill Batuzov wrote:
> Wrappers issue emulation code instead of operation if it is not supported by 
> host.
>
> tcg_gen_add_i32x4 looks like this:
>
> if (TCG_TARGET_HAS_add_i32x4) {
>     tcg_gen_op3_v128(INDEX_op_add_i32x4, args[0], args[1], args[2]);
> } else {
>     for (i = 0; i < 4; i++) {
>         tcg_gen_ld_i32(...);
>         tcg_gen_ld_i32(...);
>         tcg_gen_add_i32(...);
>         tcg_gen_st_i32(...);
>     }
> }

To me that begs the question of why you wouldn't issue 4 adds on 4 i32 
registers instead.


r~