Re: [Fortran, Patch] First patch for coarray FAILED IMAGES (TS 18508)

[Damian Rouson <damian@sourceryinstitute.org>]

Resending as plain text:

*PING*

With the 7.1.0 deadline approaching tomorrow, is there any chance of getting Alessandro’s FAILED IMAGES patch approved for trunk?  As far as I know, Fortran is the first internationally standardized language to incorporate intrinsic support for fault tolerance, which is believed to be essential to reaching exaflop performance.  As far as I know, gfortran is the first compiler to implement this Fortran 2015 feature.  This is a huge deal and I’m hoping Alessandro and I will be able to report that this is a released feature in a talk we’re giving jointly in early February.  Any assistance would be greatly appreciated.

Damian

> Begin forwarded message:
> 
> 
> From: Alessandro Fanfarillo <fanfarillo.gcc@gmail.com>
> Subject: Re: [Fortran, Patch] First patch for coarray FAILED IMAGES (TS 18508)
> Date: September 21, 2016 at 11:03:48 AM PDT
> To: Andre Vehreschild <vehre@gmx.de>
> Cc: Paul Richard Thomas <paul.richard.thomas@gmail.com>, gfortran <fortran@gcc.gnu.org>, gcc-patches <gcc-patches@gcc.gnu.org>, Mikael Morin <morin-mikael@orange.fr>, Tobias Burnus <burnus@net-b.de>
> 
> 
> Thanks Andre.
> 
> 2016-09-19 9:55 GMT-06:00 Andre Vehreschild <vehre@gmx.de>:
>> Hi Alessandro,
> 
>> The if in resolve.c at 8837: resolve_failed_image (... is intentional? It is
>> doing nothing. So do you plan to add more code, or will there never be
>> anything. If the later I recommend to just put a comment there and remove the
>> empty if.
> 
> I added the if statement during the development and I forgot to remove it.
> 
>> 
>> There still is no test when -fcoarray=single is used. This shouldn't be so
>> hard, should it?
> 
> Done.
> 
> Built and regtested on x86_64-pc-linux-gnu.
> 
>> 
>> Regards,
>>        Andre
>> 
>> On Mon, 19 Sep 2016 08:30:12 -0700
>> Alessandro Fanfarillo <fanfarillo.gcc@gmail.com> wrote:
>> 
>>> * PING *
>>> 
>>> On Sep 7, 2016 3:01 PM, "Alessandro Fanfarillo" <fanfarillo.gcc@gmail.com>
>>> wrote:
>>> 
>>>> Dear all,
>>>> the attached patch supports failed images also when -fcoarray=single is
>>>> used.
>>>> 
>>>> Built and regtested on x86_64-pc-linux-gnu.
>>>> 
>>>> Cheers,
>>>> Alessandro
>>>> 
>>>> 2016-08-09 5:22 GMT-06:00 Paul Richard Thomas <
>>>> paul.richard.thomas@gmail.com>:
>>>>> Hi Sandro,
>>>>> 
>>>>> As far as I can see, this is OK barring a couple of minor wrinkles and
>>>>> a question:
>>>>> 
>>>>> For coarray_failed_images_err.f90 and coarray_image_status_err.f90 you
>>>>> have used the option -fdump-tree-original without making use of the
>>>>> tree dump.
>>>>> 
>>>>> Mikael asked you to provide an executable test with -fcoarray=single.
>>>>> Is this not possible for some reason?
>>>>> 
>>>>> Otherwise, this is OK for trunk.
>>>>> 
>>>>> Thanks for the patch.
>>>>> 
>>>>> Paul
>>>>> 
>>>>> On 4 August 2016 at 05:07, Alessandro Fanfarillo
>>>>> <fanfarillo.gcc@gmail.com> wrote:
>>>>>> * PING *
>>>>>> 
>>>>>> 2016-07-21 13:05 GMT-06:00 Alessandro Fanfarillo <
>>>> fanfarillo.gcc@gmail.com>:
>>>>>>> Dear Mikael and all,
>>>>>>> 
>>>>>>> in attachment the new patch, built and regtested on
>>>> x86_64-pc-linux-gnu.
>>>>>>> 
>>>>>>> Cheers,
>>>>>>> Alessandro
>>>>>>> 
>>>>>>> 2016-07-20 13:17 GMT-06:00 Mikael Morin <morin-mikael@orange.fr>:
>>>>>>>> Le 20/07/2016 à 11:39, Andre Vehreschild a écrit :
>>>>>>>>> 
>>>>>>>>> Hi Mikael,
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>>>> +  if(st == ST_FAIL_IMAGE)
>>>>>>>>>>> +    new_st.op = EXEC_FAIL_IMAGE;
>>>>>>>>>>> +  else
>>>>>>>>>>> +    gcc_unreachable();
>>>>>>>>>> 
>>>>>>>>>> You can use
>>>>>>>>>>        gcc_assert (st == ST_FAIL_IMAGE);
>>>>>>>>>>        foo...;
>>>>>>>>>> instead of
>>>>>>>>>>        if (st == ST_FAIL_IMAGE)
>>>>>>>>>>                foo...;
>>>>>>>>>>        else
>>>>>>>>>>                gcc_unreachable ();
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> Be careful, this is not 100% identical in the general case. For older
>>>>>>>>> gcc version (gcc < 4008) gcc_assert() is mapped to nothing, esp. not
>>>> to
>>>>>>>>> an abort(), so the behavior can change. But in this case everything
>>>> is
>>>>>>>>> fine, because the patch is most likely not backported.
>>>>>>>>> 
>>>>>>>> Didn't know about this. The difference seems to be very subtle.
>>>>>>>> I don't mind much anyway. The original version can stay if preferred,
>>>> this
>>>>>>>> was just a suggestion.
>>>>>>>> 
>>>>>>>> By the way, if the function is inlined in its single caller, the
>>>> assert or
>>>>>>>> unreachable statement can be removed, which avoids choosing between
>>>> them.
>>>>>>>> That's another suggestion.
>>>>>>>> 
>>>>>>>> 
>>>>>>>>>>> +
>>>>>>>>>>> +  return MATCH_YES;
>>>>>>>>>>> +
>>>>>>>>>>> + syntax:
>>>>>>>>>>> +  gfc_syntax_error (st);
>>>>>>>>>>> +
>>>>>>>>>>> +  return MATCH_ERROR;
>>>>>>>>>>> +}
>>>>>>>>>>> +
>>>>>>>>>>> +match
>>>>>>>>>>> +gfc_match_fail_image (void)
>>>>>>>>>>> +{
>>>>>>>>>>> +  /* if (!gfc_notify_std (GFC_STD_F2008_TS, "FAIL IMAGE statement
>>>>>>>>>>> at %C")) */
>>>>>>>>>>> +  /*   return MATCH_ERROR; */
>>>>>>>>>>> +
>>>>>>>>>> 
>>>>>>>>>> Can this be uncommented?
>>>>>>>>>> 
>>>>>>>>>>> +  return fail_image_statement (ST_FAIL_IMAGE);
>>>>>>>>>>> +}
>>>>>>>>>>> 
>>>>>>>>>>> /* Match LOCK/UNLOCK statement. Syntax:
>>>>>>>>>>>      LOCK ( lock-variable [ , lock-stat-list ] )
>>>>>>>>>>> diff --git a/gcc/fortran/trans-intrinsic.c
>>>>>>>>>>> b/gcc/fortran/trans-intrinsic.c index 1aaf4e2..b2f5596 100644
>>>>>>>>>>> --- a/gcc/fortran/trans-intrinsic.c
>>>>>>>>>>> +++ b/gcc/fortran/trans-intrinsic.c
>>>>>>>>>>> @@ -1647,6 +1647,24 @@ trans_this_image (gfc_se * se, gfc_expr
>>>>>>>>>>> *expr) m, lbound));
>>>>>>>>>>> }
>>>>>>>>>>> 
>>>>>>>>>>> +static void
>>>>>>>>>>> +gfc_conv_intrinsic_image_status (gfc_se *se, gfc_expr *expr)
>>>>>>>>>>> +{
>>>>>>>>>>> +  unsigned int num_args;
>>>>>>>>>>> +  tree *args,tmp;
>>>>>>>>>>> +
>>>>>>>>>>> +  num_args = gfc_intrinsic_argument_list_length (expr);
>>>>>>>>>>> +  args = XALLOCAVEC (tree, num_args);
>>>>>>>>>>> +
>>>>>>>>>>> +  gfc_conv_intrinsic_function_args (se, expr, args, num_args);
>>>>>>>>>>> +
>>>>>>>>>>> +  if (flag_coarray == GFC_FCOARRAY_LIB)
>>>>>>>>>>> +    {
>>>>>>>>>> 
>>>>>>>>>> Can everything be put under the if?
>>>>>>>>>> Does it work with -fcoarray=single?
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> IMO coarray=single should not generate code here, therefore putting
>>>>>>>>> everything under the if should to fine.
>>>>>>>>> 
>>>>>>>> My point was more avoiding generating code for the arguments if they
>>>> are not
>>>>>>>> used in the end.
>>>>>>>> Regarding the -fcoarray=single case, the function returns a result,
>>>> which
>>>>>>>> can be used in an expression, so I don't think it will work without
>>>> at least
>>>>>>>> hardcoding a fixed value as result in that case.
>>>>>>>> But even that wouldn't be enough, as the function wouldn't work
>>>> consistently
>>>>>>>> with the fail image statement.
>>>>>>>> 
>>>>>>>>> Sorry for the comments ...
>>>>>>>>> 
>>>>>>>> Comments are welcome here, as far as I know. ;-)
>>>>>>>> 
>>>>>>>> Mikael
>>>>> 
>>>>> 
>>>>> 
>>>>> --
>>>>> The difference between genius and stupidity is; genius has its limits.
>>>>> 
>>>>> Albert Einstein
>>>> 
>> 
>> 
>> --
>> Andre Vehreschild * Email: vehre ad gmx dot de