in_reduction Clause

| OPENMP API Specification: "Version 5.2 -- GIT rev 95b2e3a44"

5.5.10 in_reduction Clause


Name: in_reduction	Properties: data-environment attribute, data-sharing attribute, privatization, reduction participating

Arguments


Name	Type	Properties

list	list of variable list item type	default

Modiﬁers


Name	Modiﬁes	Type	Properties

reduction-identiﬁer	list	An OpenMP reduction identiﬁer	required, ultimate

Directives

target, task, taskloop

Semantics

The in_reduction clause is a reduction participating clause, as described in Section 5.5.7, that speciﬁes that a task participates in a reduction. For a given list item, the in_reduction clause deﬁnes a task to be a participant in a task reduction that is deﬁned by an enclosing region for a matching list item that appears in a task_reduction clause or a reduction clause with task as the reduction-modiﬁer, where either:

1.: The matching list item has the same storage location as the list item in the in_reduction clause; or
2.: A private copy, derived from the matching list item, that is used to perform the task reduction has the same storage location as the list item in the in_reduction clause.

For the task construct, the generated task becomes the participating task. For each list item, a private copy may be created as if the private clause had been used.

For the target construct, the target task becomes the participating task. For each list item, a private copy may be created in the data environment of the target task as if the private clause had been used. This private copy will be implicitly mapped into the device data environment of the target device, if the target device is not the parent device.

At the end of the task region, if a private copy was created its value is combined with a copy created by a reduction scoping clause or with the original list item.

Restrictions

Restrictions to the in_reduction clause are as follows:

All restrictions common to all reduction clauses, as listed in Section 5.5.5, apply to this clause.
A list item that appears in a task_reduction clause or a reduction clause with task as the reduction-modiﬁer that is speciﬁed on a construct that corresponds to a region in which the region of the participating task is closely nested must match each list item. The construct that corresponds to the innermost enclosing region that meets this condition must specify the same reduction-identiﬁer for the matching list item as the in_reduction clause.

Cross References

target directive, see Section 13.8
task directive, see Section 12.5
taskloop directive, see Section 12.6

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