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3.7.4 omp_target_is_accessible – Check whether memory is device accessible ¶

Description:

This routine tests whether memory, starting at the address given by ptr and extending size bytes, is accessibly on the device specified by device_num. If so, it returns a nonzero value and otherwise zero.

The address given by ptr is interpreted to be in the address space of the device and size must be positive. NULL pointers and zero-length ranges always return zero.

Note that GCC’s current implementation assumes that ptr is a valid host pointer. Therefore, all non-NULL addresses given by ptr are assumed to be accessible on the initial device. The address is only reported as accessible on non-host devices if this is known to be the case, or if the device reports that all memory is accessible (i.e. [unified] shared memory access). If the runtime is uncertain it may report accessible memory as inaccessible. For a memory range to be reported accessible, the whole range must be known to be accessible.

Running this routine in a target region except on the initial device is not supported.

C/C++

Prototype:	int omp_target_is_accessible(const void *ptr,
	size_t size,
	int device_num)

Fortran:

Interface:	integer(c_int) function omp_target_is_accessible(ptr, &
	size, device_num) bind(C)
	use, intrinsic :: iso_c_binding, only: c_ptr, c_size_t, c_int
	type(c_ptr), value :: ptr
	integer(c_size_t), value :: size
	integer(c_int), value :: device_num

See also:

omp_target_associate_ptr – Associate a device pointer with a host pointer

Reference:

OpenMP specification v5.1, Section 3.8.4