Native bindings to the intel_subgroups extension.

The goal of this extension is to allow programmers to improve the performance of their applications by taking advantage of the fact that some work items in a work group execute together as a group (a "subgroup"), and that work items in a subgroup can take advantage of hardware features that are not available to work items in a work group. Specifically, this extension is designed to allow work items in a subgroup to share data without the use of local memory and work group barriers, and to utilize specialized hardware to load and store blocks of data.

There is a large amount of overlap between the functionality in this extension and the functionality in the Khronos OpenCL 2.0 "cl_khr_subgroups" extension, so this extension reuses many of the names, concepts, and functions already described in the cl_khr_subgroups extension. The key differences between the Intel subgroups extension and the Khronos subgroups extension are:

• The Khronos subgroups extension requires OpenCL 2.0, but the Intel subgroups extension may be available on OpenCL 1.2 devices.
• The Khronos subgroups extension guarantees that subgroups in a work group will make independent forward progress, but the Intel extension does not guarantee that subgroups in a work group will make independent forward progress.
• The Intel extension adds a rich set of subgroup "shuffle" functions to allow work items within a work group to interchange data without the use of local memory and work group barriers.
• The Intel extension adds a set of subgroup "block read and write" functions to take advantage of specialized hardware to read or write blocks of data from or to buffers or images.
• The Intel subgroups extension does not include the subgroup pipes functions that are included as part of the Khronos subgroups extension.
• The Intel subgroups extension does not include the device-side kernel query functions for subgroups that are included as part of the Khronos subgroups extension.

Requires CL12.