Name Strings

SPV_INTEL_int4

Contact

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

https://github.com/KhronosGroup/SPIRV-Registry

Contributors

  • Ben Ashbaugh, Intel

  • Tobias Hector, AMD

  • Stu Smith, AMD

  • Alan Baker, Google

  • Graeme Leese, Broadcom

  • Kévin Petit, Arm

  • Jeff Bolz, Nvidia

  • Ruihao Zhang, Qualcomm

Notice

Copyright (c) 2023-2025 The Khronos Group Inc. Copyright terms at http://www.khronos.org/registry/speccopyright.html

Status

  • Approved by the SPIR-V Working Group: 2025-03-12

  • Approved by the Khronos Board of Promoters: 2025-04-25

Version

Last Modified Date

2025-05-01

Revision

1

Dependencies

This extension is written against the SPIR-V Specification, Version 1.6 Revision 3.

This extension requires SPIR-V 1.0.

This extension interacts with SPV_KHR_cooperative_matrix.

Overview

Implementations may support small types that are not naturally aligned to the granularity of the implementation’s memory addressing. These types can sometimes still be supported for some operations, but require conversion or packing into larger types to load or store data in memory. This extension adds a new capability to declare a 4-bit integer type, and capabilities to allow this type to be used in cooperative matrices. 4-bit integer types can be declared in external memory only as part of a larger type that is aligned to a supported size.

Extension Name

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

OpExtension "SPV_INTEL_int4"

Modifications to the SPIR-V Specification, Version 1.6

Capabilities

Modify Section 3.31, Capability, adding this row to the table:

Capability Implicitly Declares

5112

Int4TypeINTEL
Uses OpTypeInt to specify integer types with a 'Width' of 4 and the use of conversion functions for those types.

5114

Int4CooperativeMatrixINTEL
Uses cooperative matrices with a Component Type of OpTypeInt with a 'Width' of 4.

Int4TypeINTEL, CooperativeMatrixKHR

Also see extension: SPV_KHR_cooperative_matrix

Memory Layout

Add to Section 2.18.1. Memory Layout, Int 4 layout:

Scalar integer variables with a Width of 4 can only be declared in the Private or Function storage classes. In other storage classes, they must be included in an OpTypeVector with an even Component Count, where the first component in every pair is in bits 0-3 of the corresponding byte, and the second component is in bits 4-7.

Validation Rules

Add the following bullets to section 2.16.1, Universal Validation Rules:

  • If Int4TypeINTEL is declared then the 'Width' operand of OpTypeInt may be 4.

  • If Int4CooperativeMatrixINTEL is declared then the 'Component Type' operand of OpTypeCooperativeMatrixKHR may be an OpTypeInt with a 'Width' of 4.

  • Types that are or include an integer type with a 'Width' of 4, or objects with such a type, must only be used with the following instructions:

Revision History

Rev Date Author Changes

1

2025-05-01

bashbaug

Initial revision for publication