[PATCH] Adjust PR70251 fix

[Marc Glisse]

On Tue, 22 Mar 2016, Richard Biener wrote:

> On March 22, 2016 4:55:13 PM GMT+01:00, Marc Glisse <marc.glisse@inria.fr> wrote:
>> On Tue, 22 Mar 2016, Richard Biener wrote:
>>
>>>
>>> This adjusts the PR70251 fix as discussed in the PR audit trail
>>> and fixes a bug in genmatch required (bah, stupid GENERIC comparisons
>> in
>>> GIMPLE operands...).
>>
>> Thanks !
>>
>> Hmm, the transformation is still disabled on AVX512:
>>
>>> ! /* A + (B vcmp C ? 1 : 0) -> A - (B vcmp C ? -1 : 0), since vector
>> comparisons
>>> !    return all -1 or all 0 results.  */
>>>  /* ??? We could instead convert all instances of the vec_cond to
>> negate,
>>>     but that isn't necessarily a win on its own.  */
>>>  (simplify
>>> !  (plus:c @3 (view_convert? (vec_cond:s @0 integer_each_onep@1
>> integer_zerop@2)))
>>>   (if (VECTOR_TYPE_P (type)
>>>        && TYPE_VECTOR_SUBPARTS (type) == TYPE_VECTOR_SUBPARTS
>> (TREE_TYPE (@0))
>>>        && (TYPE_MODE (TREE_TYPE (type))
>>>            == TYPE_MODE (TREE_TYPE (TREE_TYPE (@0)))))
>>> !   (minus @3 (view_convert (vec_cond @0 (negate @1) @2)))))
>>
>> It seems that the references to @0 in the "if" should use @1 instead
>> (at
>> least the last one). I assume this test is to make sure that A has as
>> many
>> integer elements of the same size as the result of the vec_cond_expr.
>
> It looks like that is always guaranteed by the input form and instead these are now useless checks which were guarding the original view-convert transform.

The input form has a view_convert_expr in it, so I don't see what prevents 
from arriving here with

v4df + view_convert((v8si < v8si) ? v8si : v8si)

for instance. That seems to indicate that some test is still needed, it is 
just better on the second or third argument of the vec_cond_expr than on 
the condition.

Or maybe you mean we could drop the view_convert_expr from the input form. 
It should have been sunk in the 2 constant arguments of the vec_cond_expr 
anyway (I didn't check if that really happens). That sounds good.

> I'll remove them in a followup.
>
> Richard.
>
>> Sorry for giving you an incomplete change in the PR.

-- 
Marc Glisse