VK_NV_compute_shader_derivatives

Other Extension Metadata

Last Modified Date

2018-07-19

IP Status

No known IP claims.

Interactions and External Dependencies

• This extension provides API support for GL_NV_compute_shader_derivatives

Contributors

• Pat Brown, NVIDIA

Description

This extension adds Vulkan support for the SPV_NV_compute_shader_derivatives SPIR-V extension.

The SPIR-V extension provides two new execution modes, both of which allow compute shaders to use built-ins that evaluate compute derivatives explicitly or implicitly. Derivatives will be computed via differencing over a 2x2 group of shader invocations. The DerivativeGroupQuadsNV execution mode assembles shader invocations into 2x2 groups, where each group has x and y coordinates of the local invocation ID of the form (2m+{0,1}, 2n+{0,1}). The DerivativeGroupLinearNV execution mode assembles shader invocations into 2x2 groups, where each group has local invocation index values of the form 4m+{0,1,2,3}.

New Structures

• Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:
  • VkPhysicalDeviceComputeShaderDerivativesFeaturesNV

New Enum Constants

• VK_NV_COMPUTE_SHADER_DERIVATIVES_EXTENSION_NAME
• VK_NV_COMPUTE_SHADER_DERIVATIVES_SPEC_VERSION
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_COMPUTE_SHADER_DERIVATIVES_FEATURES_NV

New SPIR-V Capability

• ComputeDerivativeGroupQuadsNV
• ComputeDerivativeGroupLinearNV

Issues

(1) Should we specify that the groups of four shader invocations used for derivatives in a compute shader are the same groups of four invocations that form a quad in shader subgroups?

RESOLVED: Yes.

Examples

None.

Version History

• Revision 1, 2018-07-19 (Pat Brown)
  • Initial draft