New subject: [Patch, fortran] PR85836: Implement the F2018 reduce intrinsic

2 Apr 2025

      Hi!
On Wed, 19 Mar 2025 at 19:22, Paul Richard Thomas
paul.richard.thomas@gmail.com wrote:
...
Hi Andre,
Thanks for the review - I'll act on the points that you raised.
The Linaro people reported a failure in reduce_1.f90 execution, which I believe is due to incorrect casting of 'dim' and a wrong specification of its kind. I am waiting to hear back from them as to whether or not I have fixed the failure.
Sorry I notice this message just today, so it's a bit outdated...
I've looked at bugzilla, so I've noticed that the are proper bug
reports about this now (and I've just checked, the problem is still
present on arm).
When you say you are "waiting to hear back from them as to whether or
not I have fixed the failure", did you contact us directly? (I'm
trying to understand if we missed your message, or how we could
improve communication).
Thanks,
Christophe
...
Cheers
Paul
On Wed, 19 Mar 2025 at 12:39, Andre Vehreschild vehre@gmx.de wrote:
...
Hi Paul,
I took a look at your patch and think I found some improvements needed. In
+bool
+gfc_check_reduce (gfc_expr *array, gfc_expr *operation, gfc_expr *dim,

            gfc_expr *mask, gfc_expr *identity, gfc_expr *ordered)

+{
...

if (formal->sym->attr.allocatable || formal->sym->attr.allocatable
 || formal->sym->attr.pointer || formal->sym->attr.pointer

 || formal->sym->attr.optional || formal->sym->attr.optional

 || formal->sym->ts.type == BT_CLASS || formal->sym->ts.type == BT_CLASS)

{
 gfc_error ("Each argument of OPERATION at %L shall be a scalar, "

           "non-allocatable, non-pointer, non-polymorphic and "

           "nonoptional", &operation->where);

 return false;

}

The if is only looking at the first formal argument. The right-hand sides
of the || miss a ->next-> to look at the second formal argument, right?
May be you also want to extend the tests!?
Without having looked at it, but can't you extract the whole block of

if (array->ts.type == BT_CHARACTER)
{
 unsigned long actual_size, formal_size1, formal_size2, result_size;

...

    return false;

  }

}

and share it with the checks for co_reduce? I figure way to many DRY principle
violations are in gfortran. So when we can start this, why not do it? And a
call to a routine, like check_char_arg_conformance() speaks way better, then
having to read all that code ;-)
In gfc_resolve_reduce() identity and ordered are marked as UNUSED. Should these
not a least be resolved?
Please run contrib/check_GNU_style on your patch. It reports several issues
(haven't look into their validity).
In the Changelog:

  (gfc_check_rename): Add prototype for intrinsic with 6 arguments.

  * gfortran.h: Add prototype for intrinsic with 6 arguments.

s/discription/description/
I also encountered that nit with the executable stack when working in
OpenCoarrays, but haven't had time (or desire) to look into it. I will put
myself into CC of the pr Jerry mentioned.
Besides the mentions above, this looks good to me.
Thanks for the patch and
Regards,
        Andre
On Sun, 16 Mar 2025 17:26:55 +0000
Paul Richard Thomas paul.richard.thomas@gmail.com wrote:
...
Hi All,
This version of the REDUCE intrinsic patch has evolved somewhat since the
posting on 2nd March. The most important changes are to the wrapper
function and the addition of two testsuite entries.
The wrapper function now effects:
    subroutine wrapper (a, b, c)
         type_of_ARRAY, intent(inout) :: a, c
         type_of_ARRAY, intent(inout), optional :: b
         if (present (b)) then
            c = OPERATION (a,b )
         else
            c = a
         end if
    end subroutine
The reason for wrapping OPERATION in a subroutine is to allow pointer
arithmetic to be used throughout in the library function. The only thing
that needs to be known about the type and kind of ARRAY is the element
size. The second branch in the wrapper allows deep copies to be done in the
library function, such that derived types with allocatable components do
not leak memory. This is needed at the final step of the algorithm to copy
the result from each iteration to the result and then nullify it.
This is undoubtedly a bit heavy going for intrinsic types and so, one day
soon I will possibly do a bit of M4ery. That said, the present version
works for all types of ARRAY and I worry a bit about how much this
intrinsic will be used. Thoughts?
A slight niggle is the linker error that comes up if compiled without any
optimization:
/usr/bin/ld: warning: /tmp/cc9cx9Rw.o: requires executable stack (because
the .note.GNU-stack section is executable)
I think that this is unlikely to present a security issue, however, since
it disappears at -O1, I went through each of the options triggered by -O1
but couldn't make it go away. Does anybody know why this is?
Regtests OK with FC41/x86_64 - OK for mainline?
Regards
Paul
--
Andre Vehreschild * Email: vehre ad gmx dot de

Re: [Patch, fortran] PR85836: Implement the F2018 reduce intrinsic