Vulkan-Docs/doc/specs/vulkan/appendices/VK_KHR_variable_pointers.txt
Jon Leech dbfd1b68c4 Change log for July 13, 2017 Vulkan 1.0.54 spec update:
* Bump API patch number and header version number to 54 for this update.

Github Issues:

Internal Issues:

  * Fix tessellation domain to have an upper-left origin in the
    <<img-tessellation-topology-ul, tessellation toplogy image>> and related
    language. CTS and all implementations were already doing this, it was
    just a documentation bug that it was flipped to lower-left (internal
    issue 603).
  * Add a section to the style guide describing how VUID tags are changed
    and removed when the corresponding Valid Usage statements are modified
    (internal issue 829).
  * Add explicit Valid Usage statement to
    slink:VkPipelineDynamicStateCreateInfo to require that members of
    pname:pDynamicStates must be unique (internal issue 851).

New Extensions:

  * `VK_KHR_16bit_storage`
  * `VK_KHR_dedicated_allocation`
  * `VK_KHR_external_fence`
  * `VK_KHR_external_fence_capabilities`
  * `VK_KHR_external_fence_fd`
  * `VK_KHR_external_fence_win32`
  * `VK_KHR_get_memory_requirements2`
  * `VK_KHR_storage_buffer_storage_class`
  * `VK_KHR_variable_pointers`

Extensions Promoted From KHX To KHR Status:

  * `VK_KHR_external_memory`
  * `VK_KHR_external_memory_capabilities`
  * `VK_KHR_external_memory_fd`
  * `VK_KHR_external_memory_win32`
  * `VK_KHR_external_semaphore`
  * `VK_KHR_external_semaphore_capabilities`
  * `VK_KHR_external_semaphore_fd`
  * `VK_KHR_external_semaphore_win32`
  * `VK_KHR_win32_keyed_mutex`
2017-07-11 17:57:41 -07:00

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