Re: [Qemu-devel] [PATCH v1 09/10] target-ppc: add vextu[bhw]lx instructions

[Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>]

Richard Henderson <rth@twiddle.net> writes:

> On 11/24/2016 06:53 AM, Nikunj A Dadhania wrote:
>> David Gibson <david@gibson.dropbear.id.au> writes:
>>
>>> [ Unknown signature status ]
>>> On Wed, Nov 23, 2016 at 05:07:18PM +0530, Nikunj A Dadhania wrote:
>>>> From: Avinesh Kumar <avinesku@linux.vnet.ibm.com>
>>>>
>>>> vextublx:  Vector Extract Unsigned Byte Left
>>>> vextuhlx:  Vector Extract Unsigned Halfword Left
>>>> vextuwlx:  Vector Extract Unsigned Word Left
>>>>
>>>> Signed-off-by: Avinesh Kumar <avinesku@linux.vnet.ibm.com>
>>>> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
>>>
>>> So, when I suggested doing these without helpers before, I had
>>> forgotten that the non-byte versions can straddle the word boundary.
>>> Given that the offset is in a register, not the instruction that does
>>> make it complicated.
>>>
>>> But, this version also relies on working 128-bit arithmetic, AFAICT
>>> this will just fail to build if CONFIG_INT128 isn't defined.
>>
>> It has both the implementation, just that the defines might have
>> confused you:
>>
>> #if defined(HOST_WORDS_BIGENDIAN)
>>
>> #  if defined(CONFIG_INT128)
>> #  else
>> #  endif
>>
>> #else /* !defined (HOST_WORDS_BIGENDIAN) */
>>
>> #  if defined(CONFIG_INT128)
>> #  else
>> #  endif
>>
>> #endif
>
> In include/qemu/int128.h, we do have int128_rshift.  So you don't *really* have 
> to do this by hand, exactly.

Sure, let me add int128_extract as well. Will be helpful.

Regards
Nikunj