Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

ID 767253
Date 6/24/2024
Public

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Document Table of Contents

fopenmp-target-default-sub-group-size, Qopenmp-target-default-sub-group-size

Lets you specify a default sub-group size globally for single program multiple data (SPMD) kernels that are generated for OpenMP* target constructs when offloading to SPIR64-based devices.

Syntax

Linux:

-fopenmp-target-default-sub-group-size=val

Windows:

/Qopenmp-target-default-sub-group-size:val

Arguments

val

Specifies the default fallback value.

The supported values are dependent on which sub-group sizes are supported on the hardware that the program is running on. For example, on PonteVecchio (PVC) devices, the supported values are 16 and 32.

Default

OFF

The compiler uses default heuristics when determining global simd length for kernels unless a compiler option specifies otherwise.

Description

This option lets you specify a default sub-group size globally for single program multiple data (SPMD) kernels that are generated for OpenMP target constructs when offloading to SPIR64-based devices.

This option is ignored for SIMD kernels; that is, when you also specify option -fopenmp-target-simd (Linux) or /Qopenmp-target-simd (Windows).

To use option -fopenmp-target-default-sub-group-size or /Qopenmp-target-default-sub-group-size, you must also specify option -fopenmp-targets=spir64 (Linux) or option /Qopenmp-targets:spir64 (Windows).

NOTE:

When OpenMP offloading is enabled, this option only applies to device-specific compilation.

IDE Equivalent

None

Alternate Options

None