SPV_QCOM_tile

Name Strings

SPV_QCOM_tile_shading

Contact

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

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

Contributors

Jeff Leger, Qualcomm
Ruihao Zhang, Qualcomm
Wooyoung Kim, Qualcomm

Notice

Status

Final

Version

Last Modified Date

2025-04-15

Revision

Dependencies

This extension is written against the Unified SPIR-V Specification, Version 1.6 Revision 2.

This extension requires SPIR-V 1.0.

Overview

This extension adds a new storage class and two new execution modes along with a new capability to support the Vulkan tile shading extension described in VK_QCOM_tile_shading. It also adds three new built-in variables to facilitate use of the tile shading extension.

With the new storage class, operations on 2D image/sampled image variables (i.e. tile image attachment variables) may execute per-tile while the framebuffer content is still cached in high-bandwidth on-die tile memory.

Extension Name

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

OpExtension "SPV_QCOM_tile_shading"

New Capabilities

This extension introduces a new capability:

TileShadingQCOM

New Storage Classes

Storage class added under the TileShadingQCOM capability:

TileAttachmentQCOM

New BuiltIns

BuiltIn variables added under the TileShadingQCOM capability:

TileOffsetQCOM
TileDimensionQCOM
TileApronSizeQCOM

New Execution Mode

Execution mode added under the TileShadingQCOM capability:

NonCoherentTileAttachmentReadQCOM
TileShadingRateQCOM

Modifications to the SPIR-V Specification, Version 1.6

Execution Mode

Modify Section 3.6, "Execution Mode", adding the following row before EarlyAndLateFragmentTestsAMD

Execution Mode	Extra Operands	Enabling Capabilities
4489	NonCoherentTileAttachmentReadQCOM When enabled, the mode indicates that load operations on tile image attachment variables of the TileAttachmentQCOM storage class are not guaranteed to be in rasterization order. Only valid with the Fragment Execution Model.		TileShadingQCOM
4490	TileShadingRateQCOM Indicates the shading rate in the x,y, and z dimensions for QCOM tile shading. x rate, y rate and z rate are unsigned 32-bit integers. x rate and y rate are a power of 2. Only valid with the GLCompute Execution Model.	Literal x rate	Literal y rate	Literal z rate	TileShadingQCOM

Execution Mode

Extra Operands

Enabling Capabilities

4489

NonCoherentTileAttachmentReadQCOM
When enabled, the mode indicates that load operations on tile image attachment variables of the TileAttachmentQCOM storage class are not guaranteed to be in rasterization order. Only valid with the Fragment Execution Model.

TileShadingQCOM

4490

TileShadingRateQCOM
Indicates the shading rate in the x,y, and z dimensions for QCOM tile shading. x rate, y rate and z rate are unsigned 32-bit integers. x rate and y rate are a power of 2. Only valid with the GLCompute Execution Model.

Literal x rate

Literal y rate

Literal z rate

TileShadingQCOM

Storage Class

Modify Section 3.7, "Storage Class", adding the following row before CallableDataNV:

Storage Class	Enabling Capabilities	Enabled by Extension
4491	TileAttachmentQCOM Used to specify tile image attachment variables compatible with the TileShadingQCOM capability	TileShadingQCOM	SPV_QCOM_tile_shading

Storage Class

Enabling Capabilities

Enabled by Extension

4491

TileAttachmentQCOM
Used to specify tile image attachment variables compatible with the TileShadingQCOM capability

TileShadingQCOM

SPV_QCOM_tile_shading

Builtin

Modify Section 3.21, "BuiltIn", adding the following rows to the Builtin table before BaryCoordNoPerspAMD:

BuiltIn	Enabling Capabilities
4492	TileOffsetQCOM Framebuffer coordinates (x,y) of the top-left texel of the active tile. Available only in fragment and compute shaders.	TileShadingQCOM Also see extension: SPV_QCOM_tile_shading
4493	TileDimensionQCOM Reports the tile dimension (width, height, z). (width, height) represents the tile size in pixels for the active tile and z is the number of tile layers. Available only in fragment and compute shaders.	TileShadingQCOM Also see extension: SPV_QCOM_tile_shading
4494	TileApronSizeQCOM Size (horizontal, vertical) of the apron for the active tile. Available only in fragment and compute shaders.	TileShadingQCOM Also see extension: SPV_QCOM_tile_shading

BuiltIn

Enabling Capabilities

4492

TileOffsetQCOM
Framebuffer coordinates (x,y) of the top-left texel of the active tile. Available only in fragment and compute shaders.

TileShadingQCOM
Also see extension: SPV_QCOM_tile_shading

4493

TileDimensionQCOM
Reports the tile dimension (width, height, z). (width, height) represents the tile size in pixels for the active tile and z is the number of tile layers. Available only in fragment and compute shaders.

TileShadingQCOM
Also see extension: SPV_QCOM_tile_shading

4494

TileApronSizeQCOM
Size (horizontal, vertical) of the apron for the active tile. Available only in fragment and compute shaders.

TileShadingQCOM
Also see extension: SPV_QCOM_tile_shading

Capabilities

Modify Section 3.31, "Capability", adding the following rows to the Capability table after RayTracingKHR:

Capability	Implicitly Declares
4495	TileShadingQCOM To read from tile image variables, to write to tile image variables and to sample tile image variables at the specified coordinates. Makes the TileAttachmentQCOM storage class, the TileOffsetQCOM/TileDimensionQCOM/TileApronSizeQCOM built-in variables, and the NonCoherentTileAttachmentReadQCOM and TileShadingRateQCOM execution modes available to the shader.	Shader

Capability

Implicitly Declares

4495

TileShadingQCOM
To read from tile image variables, to write to tile image variables and to sample tile image variables at the specified coordinates. Makes the TileAttachmentQCOM storage class, the TileOffsetQCOM/TileDimensionQCOM/TileApronSizeQCOM built-in variables, and the NonCoherentTileAttachmentReadQCOM and TileShadingRateQCOM execution modes available to the shader.

Shader

Validation Rules

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

OpExtension "SPV_QCOM_tile_shading"

The x and y rate values of the TileShadingRateQCOM execution mode must be powers of 2.

Issues

Revision History

Rev	Date	Author	Changes
1	2025-04-15	Wooyoung Kim	Initial version

Rev

Date

Author

Changes

2025-04-15

Wooyoung Kim

Initial version