Developer Reference

Migrating OpenCL™ FPGA Designs to SYCL*

ID 767849
Date 7/13/2023
Public

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Intra-kernel Registered Assignment Function

The following table lists the syntax for intra-kernel registered assignment function (also referred to as kernel variables in SYCL*) supported in OpenCL and SYCL:

OpenCL SYCL Description
__fpga_reg() ext::intel::fpga_reg() Directs the compiler to insert at least one register between the operand and the return value of the function call. In general, it is not necessary to include the fpga_reg() function in your kernel code to achieve desired performance.
NOTE:

Intel® strongly recommends that you use the fpga_reg() function only if you are experienced in using the Intel® Quartus® Prime Pro Edition software performing advanced optimization for a specific target device. You must have sufficient knowledge about the placement of portions of the datapath on an FPGA device.