Hi Tobias,
Am 07.09.21 um 16:33 schrieb Tobias Burnus:
Now I actually tested the patch – and fixed some issues.
OK? – It does add support for 'allocated(a[i])' by treating
it as 'allocated(a)', as 'a' must be collectively allocated
("established") on all images of the team.*
'a[i]' is (probably) an allocatable, following Malcolm in
answer to my question to the J3-list as linked below.
while still feeling somewhat unsure (given my previous comment
and the discussion), I think your patch is basically OK.
However, your testcase has a { dg-do compile }, so it does not
really do any runtime tests. Is that intended? If so, please
add a respective comment, or adjust the testcase.
Otherwise this LGTM.
Thanks for the patch!
Harald
Tobias
* Ignoring issues related to failed images. It could
also be handled by fetching 'a' from the remote
image, but I am not sure that's better in terms of
handling failed images.
PS:
On 07.09.21 10:02, Tobias Burnus wrote:
Hi Harald,
I spend yesterday about two hours with this. Now I am still
tired but understand more. I think the confusion between the
two of us is due to wording and in which directions the
thoughts then go:
Talking about coindexed, all of a[i], b[i]%c and c%d[i] are
coindexed and there are many constraints like "shall not be
a coindexed variable" – which then rejects all of those.
That's what I was thinking of.
I think your starting point is that while ('a' = allocatable)
a, b%a, c[5]%d(1)%a
are ALLOCATABLE, adding a subobject reference such as
a(:), b%a(:,:), c[5]%d(1)%a(:,:,:)
makes the variable no longer allocatable.
I think that's what you were thinking of.
We then both argued along those different lines – which caused
the confusion as we both thought we talked about the same.
While those cases are clear, the question is whether
a[i] or b%a[i]
is allocatable or not – assuming that 'a' is a scalar.
(For an array, '(:)' has to appear before the image-selector,
which in turn makes it nonallocatable.)
I tried to pinpoint the words for this in the standard – and
failed. I think I need a "how to read the Fortran standard" 101
and some long time actually reading it :-(
Malcolm has answered me – and he believes (but only offhand) that
a[i] and b%a[i]
_are_ allocatable. See (6) at
https://mailman.j3-fortran.org/pipermail/j3/2021-September/013322.html
This implies that
if ( allocated (a[i]) .and. allocated (b%a[i]) ) stop 1
is valid.
However, I do note that coarray allocatables have to be collectively
(de)allocated, therefore
allocated (a[i]) .and. allocated (b%a[i])
is equivalent to
allocated (a) .and. allocated (b%a)
at least assuming that no image has failed.
First: Does this answer all the questions you had and resolved the
confusion?
Secondly, do you agree about the last bits of the analysis?
Thirdly, what do you think of the attached patch?
Tobias
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