Re: combine vec_perm_expr with constructor

[Richard Guenther <richard dot guenther at gmail dot com>]

On Mon, Sep 3, 2012 at 4:00 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> On Mon, 3 Sep 2012, Richard Guenther wrote:
>
>> You shouldn't need the VECTOR_CST handling - constant propagation should
>> already ensure properly simplified code here (and is the more canonical
>> place
>> to handle this).
>
>
> IIRC, I added VECTOR_CST because of mixed constructor/vector_cst shuffles
> (and because it wasn't too hard). If I remove it (I can), I guess some of
> the testcases won't work anymore.

I see.  If you still have a testcase can you look if CCP does not do something
it should?

>
>> You do work above and then bail late here.  Always do early exists early
>> to reduce useless compile-time.
>
>
> Ok.
>
>
>>> +      opt = fold_ternary (VEC_PERM_EXPR, TREE_TYPE(op0), arg0, arg1,
>>> op2);
>>> +      if (!opt)
>>> +       return 0;
>>> +      gimple_assign_set_rhs_from_tree (gsi, opt);
>>
>>
>> You need to verify that fold_ternary returns something that is valid
>> GIMPLE.
>> fold () in general happily returns trees that are in the need of
>> re-gimplification.
>> You expect a CONSTRUCTOR or VECTOR_CST here, so you should check
>> for that.
>
>
> Ok.
>
> Thank you for the reviews,
>
> --
> Marc Glisse