1// Copyright (c) 2016-2018 Khronos Group. This work is licensed under a 2// Creative Commons Attribution 4.0 International License; see 3// http://creativecommons.org/licenses/by/4.0/ 4 5include::meta/VK_KHR_variable_pointers.txt[] 6 7*Last Modified Date*:: 8 2017-09-05 9*IP Status*:: 10 No known IP claims. 11*Interactions and External Dependencies*:: 12 - Requires the 13 https://www.khronos.org/registry/spir-v/extensions/KHR/SPV_KHR_variable_pointers.html[+SPV_KHR_variable_pointers+] 14 SPIR-V extension. 15 - Promoted to Vulkan 1.1 Core 16*Contributors*:: 17 - John Kessenich, Google 18 - Neil Henning, Codeplay 19 - David Neto, Google 20 - Daniel Koch, Nvidia 21 - Graeme Leese, Broadcom 22 - Weifeng Zhang, Qualcomm 23 - Stephen Clarke, Imagination Technologies 24 - Jason Ekstrand, Intel 25 - Jesse Hall, Google 26 27The `VK_KHR_variable_pointers` extension allows implementations to indicate 28their level of support for the +SPV_KHR_variable_pointers+ SPIR-V extension. 29The SPIR-V extension allows shader modules to use invocation-private 30pointers into uniform and/or storage buffers, where the pointer values can 31be dynamic and non-uniform. 32 33The +SPV_KHR_variable_pointers+ extension introduces two capabilities. 34The first, code:VariablePointersStorageBuffer, must: be supported by all 35implementations of this extension. 36The second, code:VariablePointers, is optional. 37 38=== New Enum Constants 39 40 * Extending elink:VkStructureType: 41 ** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VARIABLE_POINTER_FEATURES_KHR 42 43=== New Structures 44 45 * slink:VkPhysicalDeviceVariablePointerFeaturesKHR 46 47=== New SPIR-V Capabilities 48 49 * <<spirvenv-capabilities-table-variablepointers,VariablePointersStorageBuffer>> 50 * <<spirvenv-capabilities-table-variablepointers,VariablePointers>> 51 52=== Promotion to Vulkan 1.1 53 54All functionality in this extension is included in core Vulkan 1.1, with the 55KHR suffix omitted, however support for the 56<<features-features-variablePointersStorageBuffer, 57pname:variablePointersStorageBuffer>> feature is made optional. 58The original type, enum and command names are still available as aliases of 59the core functionality. 60 61=== Issues 62 631) Do we need an optional property for the SPIR-V 64code:VariablePointersStorageBuffer capability or should it be mandatory when 65this extension is advertised? 66 67*RESOLVED*: Add it as a distinct feature, but make support mandatory. 68Adding it as a feature makes the extension easier to include in a future 69core API version. 70In the extension, the feature is mandatory, so that presence of the 71extension guarantees some functionality. 72When included in a core API version, the feature would be optional. 73 742) Can support for these capabilities vary between shader stages? 75 76*RESOLVED*: No, if the capability is supported in any stage it must be 77supported in all stages. 78 793) Should the capabilities be features or limits? 80 81*RESOLVED*: Features, primarily for consistency with other similar 82extensions. 83 84=== Version History 85 86 * Revision 1, 2017-03-14 (Jesse Hall and John Kessenich) 87 - Internal revisions 88