Ctrl+K

USM Pointer Queries

USM Pointer Queries#

Since USM pointers look like raw C++ pointers, users cannot deduce what kind of USM allocation a given pointer may be from by examining its type.

Two functions are defined that let users query the type of a USM allocation and, if applicable, the sycl::device on which it was allocated.

Note

These query functions are only supported on the host.

See also

SYCL Specification Section 4.8.4

Pointer query functions#

sycl::get_pointer_type#

sycl::usm::alloc get_pointer_type(const void* ptr, const sycl::context& syclContext);

Returns the USM allocation type for ptr if ptr falls inside a valid USM allocation for the context syclContext.

Returns sycl::usm::alloc::unknown if ptr does not point within a valid USM allocation from syclContext.

sycl::get_pointer_device#

sycl::device get_pointer_device(const void* ptr, const sycl::context& syclContext);

Returns the sycl::device associated with the USM allocation.

If ptr points within a device USM allocation or a shared USM allocation for the context syclContext, returns the same device that was passed when allocating the memory.

If ptr points within a host USM allocation for the context syclContext, returns the first device in syclContext.

Exceptions

sycl::errc::invalid

If ptr does not point within a valid USM allocation from syclContext.

Contents