OpenCL™ offers two basic ways to trade precision for speed:
native_* and half_* math built-ins, which
have lower precision, but are faster than their un-prefixed variants-cl-fast-relaxed-math flag.In general, while the -cl-fast-relaxed-math flag is a quick
way to get performance gains for kernels with many math operations, it
does not permit fine numeric accuracy control. Consider experimenting
with the native_* equivalents separately for each specific
case, keeping track of the resulting accuracy.
Native_ versions of math built-ins are supported in hardware
and run substantially faster, while offering lower accuracy. Use native
trigonometry and transcendental functions, such as sin, cos,
exp, and log, when performance is more important
than precision.
For a full list of OpenCL build options and option descriptions, refer to the the OpenCL specification. For the instructions on how to use these options with the Intel® SDK for OpenCL™ Applications, refer to the following pages in the Developer Guide for Intel® SDK for OpenCL™ Applications: Build with OpenCL Offline Compiler Command Line Interface (for Intel® SDK for OpenCL™ Applications standalone version), Configuring OpenCL™ Build Options (for Intel® Code Builder for OpenCL™ API plugin for Microsoft Visual Studio*), Configuring Build Options (for Intel® Code Builder for OpenCL™ API plugin for Eclipse*).