On 4/15/19 11:45 PM, David Hildenbrand wrote:
> On 13.04.19 02:54, Richard Henderson wrote:
>> On 4/11/19 12:08 AM, David Hildenbrand wrote:
>>> +static DisasJumpType op_vsldb(DisasContext *s, DisasOps *o)
>>> +{
>>> + int src_idx = get_field(s->fields, i4) & 0xf;
>>> +
>>> + if (src_idx == 0) {
>>> + gen_gvec_mov(get_field(s->fields, v1), get_field(s->fields, v2));
>>> + } else {
>>> + gen_gvec_3_ool(get_field(s->fields, v1), get_field(s->fields, v2),
>>> + get_field(s->fields, v3), src_idx,
>>> + gen_helper_gvec_vsldb);
>>> + return DISAS_NEXT;
>>
>> You could also expand this inline using your new extract2 primitive.
>>
>> int i4 = get_field(s->fields, i4);
>> int left_shift, right_shift;
>>
>> left_shift = (i4 & 7) * 8;
>> right_shift = 64 - left_shift;
>>
>> if ((i4 & 8) == 0) {
>> read_vec_element_i64(t0, get_field(s->fields, v2), 0, ES_64);
>> read_vec_element_i64(t1, get_field(s->fields, v2), 1, ES_64);
>> read_vec_element_i64(t2, get_field(s->fields, v3), 0, ES_64);
>> } else {
>> read_vec_element_i64(t0, get_field(s->fields, v2), 1, ES_64);
>> read_vec_element_i64(t1, get_field(s->fields, v3), 0, ES_64);
>> read_vec_element_i64(t2, get_field(s->fields, v3), 1, ES_64);
>> }
>> tcg_gen_extract2_i64(t0, t1, t0, right_shift);
>> tcg_gen_extract2_i64(t1, t2, t1, right_shift);
>
> Trying to understand the magic, left_shift is really only used to to
> calculate right_shift, right?
Yes. I thought that was clearer as a separate step.
r~
