Re: [PATCH, 10/16] Add pass_oacc_kernels pass group in passes.def

[Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>]

On November 18, 2015 9:30:23 AM GMT+01:00, Richard Biener <rguenther@suse.de> wrote:
>On Tue, 17 Nov 2015, Tom de Vries wrote:
>
>> On 17/11/15 16:18, Richard Biener wrote:
>> > > > IMHO autopar needs to handle induction itself.
>> > > >
>> > > >I'm not sure what you mean. Could you elaborate?  Autopar
>handles
>> > > induction
>> > > >variables, but it doesn't handle exit phis reading the final
>value of the
>> > > >induction variable. Is that what you want fixed? How?
>> > Yes.  Perform final value replacement.
>> > 
>> 
>> I see. Calling scev_const_prop in pass_parallelize_loops_oacc_kernels
>seems to
>> work fine.
>> 
>> Doing the same for pass_parallelize_loops like this:
>> ...
>> diff --git a/gcc/tree-parloops.c b/gcc/tree-parloops.c
>> index 17415a8..d944395 100644
>> --- a/gcc/tree-parloops.c
>> +++ b/gcc/tree-parloops.c
>> @@ -2787,6 +2787,9 @@ pass_parallelize_loops::execute (function *fun)
>>    if (number_of_loops (fun) <= 1)
>>      return 0;
>> 
>> +  unsigned int sccp_todo = scev_const_prop ();
>> +  gcc_assert (sccp_todo == 0);
>> +
>>    if (parallelize_loops ())
>>      {
>>        fun->curr_properties &= ~(PROP_gimple_eomp);
>> ...
>> seems to fix PR 68373 - "autopar fails on loop exit phi with argument
>defined
>> outside loop".
>> 
>> The new scev_const_prop call in autopar rewrites this phi into an
>assignment,
>> and that allows parloops to succeed:
>> ...
>> final value replacement:
>>   n_2 = PHI <n_4(D)(4)>
>>   with
>>   n_2 = n_4(D);
>> ...
>
>That works for me but please factor out the final value replacement
>code from scev_const_prop.  I think best would be to have a
>helper that does final value replacement for a single loop so you
>can call it for loops to paralellize only.

Bonus points for fixing the dump_file to parse in:

>Parloops will fail because:
>...
>phi is n_2 = PHI <n_4(D)(4)>
>arg of phi to exit: value n_4(D) used outside loop
>checking if it a part of reduction pattern:

s/it a/it is/

>FAILED: it is not a part of reduction....
>...

TIA,
>
>Richard.
>
>> Thanks,
>> - Tom
>> 
>>