Re: [qemu-s390x] [Qemu-devel] [PATCH v2 13/32] s390x/tcg: Implement VECTOR LOAD MULTIPLE

[David Hildenbrand]

On 01.03.19 17:26, Richard Henderson wrote:
> On 3/1/19 3:53 AM, David Hildenbrand wrote:
>> +    /*
>> +     * Check for possible access exceptions by trying to load the last
>> +     * element. The first element will be checked first next.
>> +     */
>> +    t = tcg_temp_new_i64();
>> +    gen_addi_and_wrap_i64(s, t, o->addr1, (v3 - v1) * 16 + 8);
>> +    tcg_gen_qemu_ld_i64(t, t, get_mem_index(s), MO_TEQ);
> 
> qemu_ld expands to enough code that it is a shame to discard this value and
> reload it during this loop.  Perhaps load this to t2...
> 
>> +
>> +    for (;; v1++) {
>> +        tcg_gen_qemu_ld_i64(t, o->addr1, get_mem_index(s), MO_TEQ);
>> +        write_vec_element_i64(t, v1, 0, ES_64);
> 
> Move v1 == v3 break here...
> 
>> +        gen_addi_and_wrap_i64(s, o->addr1, o->addr1, 8);
>> +        tcg_gen_qemu_ld_i64(t, o->addr1, get_mem_index(s), MO_TEQ);
>> +        write_vec_element_i64(t, v1, 1, ES_64);
>> +        if (v1 == v3) {
>> +            break;
>> +        }
>> +        gen_addi_and_wrap_i64(s, o->addr1, o->addr1, 8);
>> +    }
> 
> ... and store t2 into v3 element 1 after the loop.

Yes, makes perfect sense, thanks!


-- 

Thanks,

David / dhildenb