Intel® FPGA SDK for OpenCL™ Standard Edition: Best Practices Guide

ID 683176
Date 9/24/2018
Document Table of Contents

7.3.3. Storing Variables and Arrays in Private Memory

The implements private memory using FPGA registers or block RAMs. The offline compiler analyzes the private memory accesses and promotes them to register accesses. The offline compiler promotes most scalar variablessuch as float, int, and char. It also promotes aggregate data types if accesses are constants at compilation time. Typically, private memory is useful for storing single variables or small arrays. Registers are plentiful hardware resources in FPGAs, and it is almost always better to use private memory instead of other memory types whenever possible. The kernel can access private memories in parallel, allowing them to provide more bandwidth than any other memory type (that is, global, local, and constant memories).

For more information on the implementation of private memory using registers, refer to the Inferring a Register section of the Standard Edition Programming Guide.