Re: [RFC][IPA-VRP] Early VRP Implementation

[Richard Biener <richard.guenther@gmail.com>]

On Thu, Sep 15, 2016 at 4:45 PM, Jeff Law <law@redhat.com> wrote:
> On 09/14/2016 11:55 PM, Richard Biener wrote:
>>
>> On September 14, 2016 11:36:16 PM GMT+02:00, Jan Hubicka <hubicka@ucw.cz>
>> wrote:
>>>>
>>>> +  /* Visit PHI stmts and discover any new VRs possible.  */
>>>> +  gimple_stmt_iterator gsi;
>>>> +  for (gphi_iterator gpi = gsi_start_phis (bb);
>>>> +       !gsi_end_p (gpi); gsi_next (&gpi))
>>>> +    {
>>>> +      gphi *phi = gpi.phi ();
>>>> +      tree lhs = PHI_RESULT (phi);
>>>> +      value_range vr_result = VR_INITIALIZER;
>>>> +      if (! has_unvisived_preds
>>>>            && stmt_interesting_for_vrp (phi)
>>>> +         && stmt_visit_phi_node_in_dom_p (phi))
>>>> +       extract_range_from_phi_node (phi, &vr_result, true);
>>>> +      else
>>>> +       set_value_range_to_varying (&vr_result);
>>>> +      update_value_range (lhs, &vr_result);
>>>> +    }
>>>>
>>>> due to a bug in IRA you need to make sure to un-set BB_VISITED after
>>>> early-vrp is finished again.
>>>
>>> How IRA bugs affects early passes?
>>
>>
>> IRA bogously relies on BB_VISITED being cleared at pass start.
>
> Seems like IRA ought to be fixed to clear BB_VISITED on every block as part
> of its initialization.

Agreed but I didn't find the time to track down an appropriate place to do that.

Richard.

> Jeff
>