2.14.4  target exit data Construct

Summary The target exit data directive specifies that list items are unmapped from a device data environment. The target exit data directive is a stand-alone directive.

Syntax

 
#pragma omp target exit data [clause[ [,] clause] ... ] new-line
  

 
if([ target exit data :] scalar-expression) 
device(integer-expression) 
map([map-type-modifier[,] [map-type-modifier[,] ...]] map-type: locator-list) 
depend([depend-modifier,] dependence-type : locator-list) 
nowait
       

 
!$omp target exit data [clause[ [,] clause] ... ]
  

 
if([ target exit data :] scalar-logical-expression) 
device(scalar-integer-expression) 
map([map-type-modifier[,] [map-type-modifier[,] ...]] map-type: locator-list) 
depend([depend-modifier,] dependence-type : locator-list) 
nowait
       

Binding The binding task set for a target exit data region is the generating task, which is the target task generated by the target exit data construct. The target exit data region binds to the corresponding target task region.

Description When a target exit data construct is encountered, the list items in the map clauses are unmapped from the device data environment according to the map clause semantics.

The target exit data construct is a task generating construct. The generated task is a target task. The generated task region encloses the target exit data region.

All clauses are evaluated when the target exit data construct is encountered. The data environment of the target task is created according to the data-mapping attribute clauses on the target exit data construct, per-data environment ICVs, and any default data-sharing attribute rules that apply to the target exit data construct. If a variable or part of a variable is mapped by the target exit data construct, the variable has a default data-sharing attribute of shared in the data environment of the target task.

Assignment operations associated with mapping a variable (see Section 2.21.7.1) occur when the target task executes.

If the nowait clause is present, execution of the target task may be deferred. If the nowait clause is not present, the target task is an included task.

If a depend clause is present, it is associated with the target task.

If no device clause is present, the behavior is as if the device clause appears with an expression equal to the value of the default-device-var ICV.

When an if clause is present and the if clause expression evaluates to false, the target device is the host.

Execution Model Events Events associated with a target task are the same as for the task construct defined in Section 2.12.1.

The target-exit-data-begin event occurs when a thread enters a target exit data region.

The target-exit-data-end event occurs when a thread exits a target exit data region.

Tool Callbacks Callbacks associated with events for target tasks are the same as for the task construct defined in Section 2.12.1; (flags & ompt_task_target) always evaluates to true in the dispatched callback.

A thread dispatches a registered ompt_callback_target or ompt_callback_target_emi callback with ompt_scope_begin as its endpoint argument and ompt_target_exit_data or ompt_target_exit_data_nowait if the nowait clause is present as its kind argument for each occurrence of a target-exit-data-begin event in that thread in the context of the target task on the host. Similarly, a thread dispatches a registered ompt_callback_target or ompt_callback_target_emi callback with ompt_scope_end as its endpoint argument and ompt_target_exit_data or ompt_target_exit_data_nowait if the nowait clause is present as its kind argument for each occurrence of a target-exit-data-end event in that thread in the context of the target task on the host. These callbacks have type signature ompt_callback_target_t or ompt_callback_target_emi_t, respectively.

Restrictions Restrictions to the target exit data construct are as follows:

• A program must not depend on any ordering of the evaluations of the clauses of the target exit data directive, or on any side effects of the evaluations of the clauses.
• At least one map clause must appear on the directive.
• At most one device clause can appear on the directive. The device clause expression must evaluate to a non-negative integer value that is less than or equal to the value of omp_get_num_devices().
• At most one if clause can appear on the directive.
• A map-type must be specified in all map clauses and must be either from, release, or delete.
• At most one nowait clause can appear on the directive.

Cross References

• default-device-var, see Section 2.4.1.
• task, see Section 2.12.1.
• task scheduling constraints, see Section 2.12.6.
• target data, see Section 2.14.2.
• target enter data, see Section 2.14.3.
• if clause, see Section 2.18.
• map clause, see Section 2.21.7.1.
• omp_get_num_devices routine, see Section 3.7.4.
• ompt_callback_target_t and ompt_callback_target_emi_t callback type, see Section 4.5.2.26.