Re: [Qemu-devel] [PATCH v4 4/9] target-ppc: improve lxvw4x implementation

[Nikunj A Dadhania]

David Gibson <address@hidden> writes:

> [ Unknown signature status ]
> On Wed, Sep 28, 2016 at 11:01:22AM +0530, Nikunj A Dadhania wrote:
>> Load 8byte at a time and manipulate.
>> 
>> Big-Endian Storage
>> +-------------+-------------+-------------+-------------+
>> | 00 11 22 33 | 44 55 66 77 | 88 99 AA BB | CC DD EE FF |
>> +-------------+-------------+-------------+-------------+
>> 
>> Little-Endian Storage
>> +-------------+-------------+-------------+-------------+
>> | 33 22 11 00 | 77 66 55 44 | BB AA 99 88 | FF EE DD CC |
>> +-------------+-------------+-------------+-------------+
>> 
>> Vector load results in:
>> +-------------+-------------+-------------+-------------+
>> | 00 11 22 33 | 44 55 66 77 | 88 99 AA BB | CC DD EE FF |
>> +-------------+-------------+-------------+-------------+
>
> Ok.  I'm guessing from this that implementing those GPR<->VSR
> instructions showed that the earlier versions were endian-incorrect as
> I suspected.
>
> Have you verified that this new implementation is actually faster (or
> at least no slower) on LE than the original implementation with
> individual 32-bit stores?

I haven't, will check it once and get back.

Regards
Nikunj