On 10/18/18, Richard Sandiford <richard.sandif...@arm.com> wrote:
> "H.J. Lu" <hjl.to...@gmail.com> writes:
>> On 10/18/18, Richard Sandiford <richard.sandif...@arm.com> wrote:
>>> "H.J. Lu" <hjl.to...@gmail.com> writes:
>>>> On 10/18/18, Richard Sandiford <richard.sandif...@arm.com> wrote:
>>>>> "H.J. Lu" <hjl.to...@gmail.com> writes:
>>>>>> On 10/17/18, Marc Glisse <marc.gli...@inria.fr> wrote:
>>>>>>> On Wed, 17 Oct 2018, H.J. Lu wrote:
>>>>>>>
>>>>>>>> We may simplify
>>>>>>>>
>>>>>>>> (subreg (vec_merge (vec_duplicate X) (vector) (const_int 1)) 0)
>>>>>>>>
>>>>>>>> to X when mode of X is the same as of mode of subreg.
>>>>>>>
>>>>>>> Hello,
>>>>>>>
>>>>>>> we already have code to simplify vec_select(vec_merge):
>>>>>>>
>>>>>>> /* If we select elements in a vec_merge that all come from the
>>>>>>> same
>>>>>>> operand, select from that operand directly. */
>>>>>>>
>>>>>>> It would make sense to me to make the subreg transform as similar to
>>>>>>> it
>>>>>>> as
>>>>>>> possible, in particular you don't need to special case
>>>>>>> vec_duplicate,
>>>>>>> the
>>>>>>> transformation would see that everything comes from the first
>>>>>>> vector,
>>>>>>> produce (subreg (vec_duplicate X) 0), and let another transformation
>>>>>>> optimize that.
>>>>>
>>>>> Sorry, didn't see this before the OK.
>>>>>
>>>>>> What do you mean by another transformation? If simplify_subreg
>>>>>> doesn't
>>>>>> return X for
>>>>>>
>>>>>> (subreg (vec_merge (vec_duplicate X)
>>>>>> (vector)
>>>>>> (const_int ((1 << N) | M)))
>>>>>> (N * sizeof (X)))
>>>>>>
>>>>>>
>>>>>> no further transformation will be done.
>>>>>
>>>>> I think the point was that we should transform:
>>>>>
>>>>> (subreg (vec_merge X
>>>>> (vector)
>>>>> (const_int ((1 << N) | M)))
>>>>> (N * sizeof (X)))
>>>>>
>>>>> into:
>>>>>
>>>>> simplify_gen_subreg (outermode, X, innermode, byte)
>>>>>
>>>>> which should further simplify when X is a vec_duplicate.
>>>>
>>>> But sizeof (X) is the size of scalar of vec_dup. How do we
>>>> check the mask of vec_merge?
>>>
>>> Yeah, should be sizeof (outermode) (which was the same thing
>>> in the original pattern, but not here).
>>>
>>> Richard
>>>
>>
>> Like this
>>
>> diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
>> index b0cf3bbb2a9..e12b5c0e165 100644
>> --- a/gcc/simplify-rtx.c
>> +++ b/gcc/simplify-rtx.c
>> @@ -6601,20 +6601,21 @@ simplify_subreg (machine_mode outermode, rtx op,
>> return NULL_RTX;
>> }
>>
>> - /* Return X for
>> - (subreg (vec_merge (vec_duplicate X)
>> + /* Simplify
>> + (subreg (vec_merge (X)
>> (vector)
>> (const_int ((1 << N) | M)))
>> - (N * sizeof (X)))
>> + (N * sizeof (outermode)))
>> + to
>> + (subreg ((X) (N * sizeof (outermode)))
>
> Stray "(": (subreg (X) (N * sizeof (outermode)))
>
> OK with that change if it passes testing.
The self-test failed for 32-bit compiler:
expected: (reg:QI 342)
actual: (subreg:QI (vec_merge:V128QI (vec_duplicate:V128QI (reg:QI 342))
(reg:V128QI 343)
(const_int 65 [0x41])) 64)
since
&& (UINTVAL (XEXP (op, 2)) & (HOST_WIDE_INT_1U << idx)) != 0)
works only up to vectors with 64 elements for 32-bit compilers.
Should we limit the
self-test to vectors with 64 elements?
--
H.J.
