97 lines
3.1 KiB
Plaintext
97 lines
3.1 KiB
Plaintext
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// Copyright (c) 2016-2017 Khronos Group. This work is licensed under a
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// Creative Commons Attribution 4.0 International License; see
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// http://creativecommons.org/licenses/by/4.0/
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[[VK_KHR_variable_pointers]]
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== VK_KHR_variable_pointers
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*Name String*::
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VK_KHR_variable_pointers
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*Extension Type*::
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Device extension
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*Registered Extension Number*::
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121
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*Status*::
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Draft
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*Last Modified Date*::
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2017-03-14
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*Revision*::
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1
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*IP Status*::
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No known IP claims.
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*Dependencies*::
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- Written against version 1.0 of the Vulkan API
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- Requires Vulkan 1.0
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- Requires the
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<<VK_KHR_get_physical_device_properties2,VK_KHR_get_physical_device_properties2>>
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extension
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- Requires the
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<<VK_KHR_storage_buffer_storage_class,VK_KHR_storage_buffer_storage_class>>
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extension
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- Requires the
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https://www.khronos.org/registry/spir-v/extensions/KHR/SPV_KHR_variable_pointers.html[+SPV_KHR_variable_pointers+]
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SPIR-V extension.
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*Contributors*::
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- John Kessenich, Google
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- Neil Henning, Codeplay
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- David Neto, Google
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- Daniel Koch, Nvidia
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- Graeme Leese, Broadcom
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- Weifeng Zhang, Qualcomm
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- Stephen Clarke, Imagination Technologies
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- Jason Ekstrand, Intel
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- Jesse Hall, Google
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*Contacts*::
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- Jesse Hall (jessehall 'at' google.com)
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- John Kessenich (johnkessenich 'at' google.com)
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The +VK_KHR_variable_pointers+ extension allows implementations to indicate
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their level of support for the +SPV_KHR_variable_pointers+ SPIR-V extension.
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The SPIR-V extension allows shader modules to use invocation-private
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pointers into uniform and/or storage buffers, where the pointer values can
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be dynamic and non-uniform.
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The +SPV_KHR_variable_pointers+ extension introduces two capabilities.
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The first, +VariablePointersStorageBuffer+, must: be supported by all
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implementations of this extension.
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The second, +VariablePointers+, is optional.
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=== New Enum Constants
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* Extending elink:VkStructureType:
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** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VARIABLE_POINTER_FEATURES_KHR
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=== New Structures
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* slink:VkPhysicalDeviceVariablePointerFeaturesKHR
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=== New SPIR-V Capabilities
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* <<spirvenv-capabilities-table-variablepointers,VariablePointersStorageBuffer>>
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* <<spirvenv-capabilities-table-variablepointers,VariablePointers>>
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=== Issues
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1) Do we need an optional property for the SPIR-V
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+VariablePointersStorageBuffer+ capability or should it be mandatory when
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this extension is advertised?
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*RESOLVED*: Add it as a distinct feature, but make support mandatory.
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Adding it as a feature makes the extension easier to include in a future
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core API version.
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In the extension, the feature is mandatory, so that presence of the
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extension guarantees some functionality.
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When included in a core API version, the feature would be optional.
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2) Can support for these capabilities vary between shader stages?
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*RESOLVED*: No, if the capability is supported in any stage it must be
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supported in all stages.
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3) Should the capabilities be features or limits?
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*RESOLVED*: Features, primarily for consistency with other similar
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extensions.
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=== Version History
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* Revision 1, 2017-03-14 (Jesse Hall and John Kessenich)
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- Internal revisions
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