1// Copyright 2016-2023 The Khronos Group Inc.
2//
3// SPDX-License-Identifier: CC-BY-4.0
4
5include::{generated}/meta/{refprefix}VK_KHR_variable_pointers.adoc[]
6
7=== Other Extension Metadata
8
9*Last Modified Date*::
10    2017-09-05
11*IP Status*::
12    No known IP claims.
13*Interactions and External Dependencies*::
14  - This extension requires
15    {spirv}/KHR/SPV_KHR_variable_pointers.html[`SPV_KHR_variable_pointers`]
16  - Promoted to Vulkan 1.1 Core
17*Contributors*::
18  - John Kessenich, Google
19  - Neil Henning, Codeplay
20  - David Neto, Google
21  - Daniel Koch, Nvidia
22  - Graeme Leese, Broadcom
23  - Weifeng Zhang, Qualcomm
24  - Stephen Clarke, Imagination Technologies
25  - Faith Ekstrand, Intel
26  - Jesse Hall, Google
27
28=== Description
29
30The `VK_KHR_variable_pointers` extension allows implementations to indicate
31their level of support for the `SPV_KHR_variable_pointers` SPIR-V extension.
32The SPIR-V extension allows shader modules to use invocation-private
33pointers into uniform and/or storage buffers, where the pointer values can
34be dynamic and non-uniform.
35
36The `SPV_KHR_variable_pointers` extension introduces two capabilities.
37The first, code:VariablePointersStorageBuffer, must: be supported by all
38implementations of this extension.
39The second, code:VariablePointers, is optional.
40
41=== Promotion to Vulkan 1.1
42
43All functionality in this extension is included in core Vulkan 1.1, with the
44KHR suffix omitted, however support for the
45<<features-variablePointersStorageBuffer,
46pname:variablePointersStorageBuffer>> feature is made optional.
47The original type, enum and command names are still available as aliases of
48the core functionality.
49
50include::{generated}/interfaces/VK_KHR_variable_pointers.adoc[]
51
52=== New SPIR-V Capabilities
53
54  * <<spirvenv-capabilities-table-VariablePointers, code:VariablePointers>>
55  * <<spirvenv-capabilities-table-VariablePointersStorageBuffer,
56    code:VariablePointersStorageBuffer>>
57
58=== Issues
59
601) Do we need an optional property for the SPIR-V
61code:VariablePointersStorageBuffer capability or should it be mandatory when
62this extension is advertised?
63
64*RESOLVED*: Add it as a distinct feature, but make support mandatory.
65Adding it as a feature makes the extension easier to include in a future
66core API version.
67In the extension, the feature is mandatory, so that presence of the
68extension guarantees some functionality.
69When included in a core API version, the feature would be optional.
70
712) Can support for these capabilities vary between shader stages?
72
73*RESOLVED*: No, if the capability is supported in any stage it must be
74supported in all stages.
75
763) Should the capabilities be features or limits?
77
78*RESOLVED*: Features, primarily for consistency with other similar
79extensions.
80
81=== Version History
82
83  * Revision 1, 2017-03-14 (Jesse Hall and John Kessenich)
84  ** Internal revisions
85