Hi PA,
Paul-Antoine Arras wrote:
On 29/10/2025 18:44, Tobias Burnus wrote:
This does not seem to work in general:
integer :: cnt, x
cnt = 0
!$omp begin metadirective when(user={condition(cnt > 0)} : parallel)
x = 5
!$omp end metadirective
1234 format("Hello")
write(*,1234)
!$omp begin metadirective when(user={condition(x > 0)} : parallel)
x = 5
!$omp end metadirective
4567 print *, 'hello', cnt
cnt = cnt + 1
if (cnt < 2) goto 4567
end
Here is a revamped version of the patch that should handle properly
more cases.
There is still a warning with -Wall:
Warning: Label 4567 at (1) defined but not used [-Wunused-label]
Warning: Label 1234 at (1) defined but not used [-Wunused-label]
That's handled by gfc_reference_st_label, but the question is:
why doesn't this work here?
* * *
It seems as if this is due parsing the body multiple times. I see
in the first call to gfc_rebind_label:
(gdb) p label->ns->st_labels
$20 = (gfc_st_label *) 0x3752060
(gdb) p *label->ns->st_labels
$17 = {priority = 32547, left = 0x3757d00, right = 0x0, value = 1234, defined =
ST_LABEL_FORMAT, referenced = ST_LABEL_UNKNOWN, format = 0x3757a30,
backend_decl = 0x0, where = {nextc = 0x37402f0, u = {lb = 0x37402c0, location =
57934528}}, ns = 0x3750520, omp_region = 1}
(gdb) p *label->ns->st_labels->left
$18 = {priority = 20296, left = 0x0, right = 0x0, value = 1234, defined =
ST_LABEL_FORMAT, referenced = ST_LABEL_UNKNOWN, format = 0x3757e70,
backend_decl = 0x0, where = {nextc = 0x37402f0, u = {lb = 0x37402c0, location =
57934528}}, ns = 0x3750520, omp_region = 2}
The call is:
gfc_rebind_label (label=0x3757d00, new_omp_region=new_omp_region@entry=0)
Thus, only the st_labels->left is fixed, st_labels remains (unused) in
the wrong scope.
* * *
This is fixed if you move the label handling a few lines up
above the '}' of the 'while (variant)' loop.
* * *
* * *
However, we still run into the same issue that I alluded
in PR122508. We need the use the following value for
omp_region:
1111 FORMAT("outside") ! → omp_region = 0
!$omp metadirective when(... : parallel)
2222 FORMAT("outer") ! → omp_region = 1 (parallel), 2 (nothing)
!$omp metadirective when(... : parallel)
3333 FORMAT("inner")
! → omp_region = 3 (parallel,parallel)
! → omp_region = 4 (parallel,nothing)
! → omp_region = 5 (nothing,parallel)
! → omp_region = 6 (nothing,nothing)
!$omp end parallel
4444 FORMAT("outer 2") ! → omp_region = 1 (parallel), 2 (nothing)
!$omp end parallel
5555 FORMAT("outside 2") ! → omp_region = 0
Currently, we get (without -Wall or with moving it
to 'variant'):
9 | write(*,1234)
| 1
Error: FORMAT label 1234 at (1) not defined with:
For:
integer :: cnt, x
cnt = 0
!$omp begin metadirective when(user={condition(cnt > 0)} : parallel)
!$omp begin metadirective when(user={condition(cnt > 0)} : parallel)
x = 5
!$omp end metadirective
1234 format("Hello")
write(*,1234)
!$omp end metadirective
end
And likewise for the second testcase in the file,
just with 4 times:
Error: Label 4567 referenced at (1) is never defined
* * *
BTW: Can you add -Wall or -Wunused-label to all testcases?
* * *
1345 format("The count is ", g0)
...
!$omp begin metadirective when(user={condition(cnt > 0)} : parallel)
write(*,1345) cnt
!$omp end metadirective
end
I have now created a new PR for that: https://gcc.gnu.org/PR122508.
I have attached a draft patch. For the simple case of
a single metadirective it works fine. - It fails if
one nests them.
Currently we have only the latest used label available -
but we need at least the last parent one for this use
and for PR122508, we need to find all previous ones.
Thus, maybe something like:
vec<int> gfc_omp_metadirective_region_count
or
std::vector<int> gfc_omp_metadirective_region_count
where we push/pop the current count value.
And a separate variable which keeps track of the used
version.
* * *
BTW: Please consider to handle PR122508 as part of this
issue; it seems as if doing so using a stack as mentioned
above + tweaking the existing patch to PR122508 (+ adding
the two tests) should be straight forward.
Sorry that I keep finding issues :-/
Tobias
