VK_EXT_shader_atomic_float2

Other Extension Metadata

Last Modified Date

2020-08-14

IP Status

No known IP claims.

Interactions and External Dependencies

• This extension provides API support for GLSL_EXT_shader_atomic_float2

Contributors

• Faith Ekstrand, Intel

Description

This extension allows a shader to perform 16-bit floating-point atomic operations on buffer and workgroup memory as well as floating-point atomic minimum and maximum operations on buffer, workgroup, and image memory. It advertises the SPIR-V AtomicFloat16AddEXT capability which allows atomic add operations on 16-bit floating-point numbers and the SPIR-V AtomicFloat16MinMaxEXT, AtomicFloat32MinMaxEXT and AtomicFloat64MinMaxEXT capabilities which allow atomic minimum and maximum operations on floating-point numbers. The supported operations include OpAtomicFAddEXT, OpAtomicFMinEXT and OpAtomicFMaxEXT.

New Structures

• Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:
  • VkPhysicalDeviceShaderAtomicFloat2FeaturesEXT

New Enum Constants

• VK_EXT_SHADER_ATOMIC_FLOAT_2_EXTENSION_NAME
• VK_EXT_SHADER_ATOMIC_FLOAT_2_SPEC_VERSION
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_SHADER_ATOMIC_FLOAT_2_FEATURES_EXT

Issues

1) Should this extension add support for 16-bit image atomics?

RESOLVED: No. While Vulkan supports creating storage images with VK_FORMAT_R16_SFLOAT and doing load and store on them, the data in the shader has a 32-bit representation. Vulkan currently has no facility for even basic reading or writing such images using 16-bit float values in the shader. Adding such functionality would be required before 16-bit image atomics would make sense and is outside the scope of this extension.

New SPIR-V Capabilities

• AtomicFloat32MinMaxEXT
• AtomicFloat32MinMaxEXT
• AtomicFloat32MinMaxEXT
• AtomicFloat64MinMaxEXT

Version History

• Revision 1, 2020-08-14 (Faith Ekstrand)
  • Internal revisions