On 13.04.19 01:01, Richard Henderson wrote:
> On 4/11/19 12:08 AM, David Hildenbrand wrote:
>> + read_vec_element_i32(sum, get_field(s->fields, v3), 1, ES_32);
>> + for (i = 0; i < 4; i++) {
>> + read_vec_element_i32(tmp, get_field(s->fields, v2), i, ES_32);
>> + tcg_gen_add_i32(sum, sum, tmp);
>> + tcg_gen_setcond_i32(TCG_COND_LTU, tmp, sum, tmp);
>> + tcg_gen_add_i32(sum, sum, tmp);
>> + }
>> + zero_vec(get_field(s->fields, v1));
>> + write_vec_element_i32(sum, get_field(s->fields, v1), 1, ES_32);
>
> It seems like it should be possible to implement this with i64, and fold the
> carry around at the end -- 2 insns instead of 12 for managing carry. But I
> can't quite tell if that produces the same results.
I had the same in mind but also wasn't sure if it would produce the
exact same result. Feels like it should.
>
> You could use
>
> tcg_gen_add2_i32(sum, tmp, sum, zero, tmp, zero);
> tcg_gen_add_i32(sum, sum, tmp);
That makes perfect sense, I will use that for now, thanks!
>
> instead of computing carry manually with setcond.
>
> That said, your code exactly matches the language in the manual, so
>
> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
>
>
> r~
>
--
Thanks,
David / dhildenb
