2021-08-09 15:44:27 +01:00
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! RUN: %python %S/test_symbols.py %s %flang_fc1 -fopenmp
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2019-09-17 17:52:46 -07:00
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! 2.15.3 Data-Sharing Attribute Clauses
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! A list item that specifies a given variable may not appear in more than
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! one clause on the same directive, except that a variable may be specified
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! in both firstprivate and lastprivate clauses.
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!DEF: /MainProgram1/a (Implicit) ObjectEntity REAL(4)
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a = 1.
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!$omp parallel do firstprivate(a) lastprivate(a)
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[flang] [OpenMP] Predetermined rule for sequential loop index (flang-compiler/f18#976)
This commit implements rule:
A loop iteration variable for a sequential loop in a parallel or
task generating construct is private in the innermost such construct
that encloses the loop.
A Simple example:
```
i = -1 <== Scope 0
j = -1
!$omp parallel <== Scope 1
print *,i,j <-- both are shared (Scope 0)
!$omp parallel <== Scope 2
print *,i,j <-- a) i is shared (Scope 0), j is private (Scope 2)
!$omp do <== Scope 3
do i=1, 10 <-- i is private (Scope 3)
do j=1, 10 <-- b) j is private (Scope 2, not 3!)
enddo
enddo
print *,i,j <-- c) i is shared (Scope 0), j is private (Scope 2)
!$omp end parallel
print *,i,j <-- both are shared (Scope 0)
!$omp end parallel
print *,i,j <-- both are shared (Scope 0)
end
```
Ideally the above rule solves a), b), and c) but a) is left as a TODO
because it is better to handle the data-sharing attribute conflicts
along with the rules for "Predetermined DSA on Clauses".
The basic idea is when visiting the `DoConstruct` node within an OpenMP
construct, if the do-loop is not associated (like `i` loop is associated
with `!$omp do`) AND the do-loop is in the parallel/task generating
construct, resolve the loop index to be private to that innermost construct.
In the above example, `j` loop is not associated (then it is sequential) and
the innermost parallel/task generating construct that encloses the `j` loop
is the `parallel` construct marked with `<== Scope 2`, so `j` is private
to that construct. To do that, I also need to change the prototype of those
`ResolveOmp*` functions to allow specifiying the `scope` because the new
symbol for `j` should be created in Scope 2 and all the `symbol` field of
`Name j` in that `parallel` construct should be fixed, such as c).
Original-commit: flang-compiler/f18@69a845283b058a3644053ec58b00d3361f4d4a59
Reviewed-on: https://github.com/flang-compiler/f18/pull/976
2020-02-18 16:27:43 -08:00
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!DEF: /MainProgram1/Block1/i (OmpPrivate, OmpPreDetermined) HostAssoc INTEGER(4)
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2019-09-17 17:52:46 -07:00
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do i=1,10
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!DEF: /MainProgram1/Block1/a (OmpFirstPrivate, OmpLastPrivate) HostAssoc REAL(4)
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a = 2.
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end do
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end program
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