3.8.2  omp_target_free

Summary The omp_target_free routine frees the device memory allocated by the omp_target_alloc routine.

Format

 
void omp_target_free(void *device_ptr, int device_num);
  

 
subroutine omp_target_free(device_ptr, device_num) bind(c) 
use, intrinsic :: iso_c_binding, only : c_ptr, c_int 
type(c_ptr), value :: device_ptr 
integer(c_int), value :: device_num
  

Constraints on Arguments A program that calls omp_target_free with a non-null pointer that does not have a value returned from omp_target_alloc is non-conforming. The device_num argument must be greater than or equal to zero and less than or equal to the result of omp_get_num_devices().

Binding The binding task set for an omp_target_free region is the generating task, which is the target task generated by the call to the omp_target_free routine.

Effect The omp_target_free routine frees the memory in the device data environment associated with device_ptr. If device_ptr is NULL (or C_NULL_PTR, for Fortran), the operation is ignored.

The omp_target_free routine executes as if part of a target task that is generated by the call to the routine and that is an included task.

Synchronization must be inserted to ensure that all accesses to device_ptr are completed before the call to omp_target_free.

Execution Model Events The target-data-free-begin event occurs before a thread initiates a data free on a target device.

The target-data-free-end event occurs after a thread initiates a data free on a target device.

Tool Callbacks A thread dispatches a registered ompt_callback_target_data_op_emi callback with ompt_scope_begin as its endpoint argument for each occurrence of a target-data-free-begin event in that thread. Similarly, a thread dispatches a registered ompt_callback_target_data_op_emi callback with ompt_scope_end as its endpoint argument for each occurrence of a target-data-free-end event in that thread. These callbacks have type signature ompt_callback_target_data_op_emi_t.

A thread dispatches a registered ompt_callback_target_data_op callback for each occurrence of a target-data-free-begin event in that thread. The callback occurs in the context of the target task and has type signature ompt_callback_target_data_op_t.

Restrictions Restrictions to the omp_target_free routine are as follows.

• When called from within a target region the effect is unspecified.

Cross References

• target construct, see Section 2.14.5.
• omp_get_num_devices routine, see Section 3.7.4.
• omp_target_alloc routine, see Section 3.8.1.
• ompt_callback_target_data_op_t or ompt_callback_target_data_op_emi_t callback type, see Section 4.5.2.25.