2.9 Directive Nesting

 

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Dynamic nesting of directives must adhere to the following rules:

• A parallel directive dynamically inside another parallel logically establishes a new team, which is composed of only the current thread, unless nested parallelism is enabled.

• for, sections, and single directives that bind to the same parallel are not allowed to be nested inside each other.

• critical directives with the same name are not allowed to be nested inside each other. Note this restriction is not sufficient to prevent deadlock.

• for, sections, and single directives are not permitted in the dynamic extent of critical, ordered, and master regions if the directives bind to the same parallel as the regions.

• barrier directives are not permitted in the dynamic extent of for, ordered, sections, single, master, and critical regions if the directives bind to the same parallel as the regions.

• master directives are not permitted in the dynamic extent of for, sections, and single directives if the master directives bind to the same parallel as the work-sharing directives.

• ordered directives are not allowed in the dynamic extent of critical regions if the directives bind to the same parallel as the regions.

• Any directive that is permitted when executed dynamically inside a parallel region is also permitted when executed outside a parallel region. When executed dynamically outside a user-specified parallel region, the directive is executed by a team composed of only the master thread.