Name Strings

SPV_QCOM_subgroup_size

Contact

To report problems with this extension, please open a new issue at:

Contributors

  • Balaji Calidas, Qualcomm

  • Po-Sheng Chen, Qualcomm

  • Victor Lomuller, Qualcomm

  • Wooyoung Kim, Qualcomm

Notice

Copyright (c) 2024 The Khronos Group Inc. Copyright terms at http://www.khronos.org/registry/speccopyright.html

Status

  • Final

Version

Last Modified Date

2026-03-17

Revision

1

Dependencies

This extension is written against the SPIR-V Specification, Version 1.6 Revision 6.

This extension requires SPIR-V 1.1.

Overview

This extension adds two new execution modes with which an application executes subgroup operations in a shader or kernel. Shaders/kernels with the "half" execution mode will run with half the maximum subgroup size the implementation supports. Similarly, those with "full" will run with the maximum subgroup size the implementation supports. In case where a shader/kernel enables the extension, but has neither of the execution modes, the implementation selects the either full or half the maximum subgroup size it supports.

Extension Name

To use this extension within a SPIR-V module, the following OpExtension must be present in the module:

OpExtension "SPV_QCOM_subgroup_size"

New Capabilities

This extension introduces the following new capability:

SubgroupSizeQCOM

New Execution Modes

The extension adds the following new execution modes.

SubgroupSizeHalfQCOM
SubgroupSizeFullQCOM

Modifications to the SPIR-V Specification, Version 1.6

Capabilities

Modify Section 3.2.30, "Capability", adding the row to the Capability table:

Capability Implicitly declares

4506

SubgroupSizeQCOM
Enable the QCOM-extended full/half subgroup size execution modes.

Execution Mode

Modify Section 3.2.5. "Execution Mode", adding the following row to the Execution Mode table:

Execution Mode Extra Operands Enabling Capabilities

4507

SubgroupSizeHalfQCOM
Run the shader or kernel with half the maximum subgroup size the implementation supports.

SubgroupSizeQCOM

4508

SubgroupSizeFullQCOM
Run the shader or kernel with the maximum subgroup size the implementation supports.

SubgroupSizeQCOM

Validation Rules

An OpExtension must be added to the SPIR-V for validation layers to check legal use of this extension:

OpExtension "SPV_QCOM_subgroup_size"

A shader or kernel must not specify both the SubgroupSizeHalfQCOM and SubgroupSizeFullQCOM execution modes.

Issues

Revision History

Rev Date Author Changes

1

2026-03-17

Wooyoung Kim

Initial version