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Add SPV_EXT_long_vector (#377)
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‎README.md‎

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* [SPV_EXT_fragment_invocation_density ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_fragment_invocation_density.html)
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* [SPV_EXT_fragment_shader_interlock ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_fragment_shader_interlock.html)
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* [SPV_EXT_image_raw10_raw12 ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_image_raw10_raw12.html)
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* [SPV_EXT_long_vector ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_long_vector.html)
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* [SPV_EXT_mesh_shader ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_mesh_shader.html)
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* [SPV_EXT_opacity_micromap ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_opacity_micromap.html)
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* [SPV_EXT_optnone ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_optnone.html)

‎extensions/EXT/SPV_EXT_long_vector.asciidoc‎

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SPV_EXT_long_vector
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===================
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Name Strings
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------------
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SPV_EXT_long_vector
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Contact
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-------
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To report problems with this extension, please open a new issue at:
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https://github.com/KhronosGroup/SPIRV-Headers
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Contributors
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------------
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- Jeff Bolz, NVIDIA
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Notice
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------
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Copyright (c) 2025 The Khronos Group Inc. Copyright terms at
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http://www.khronos.org/registry/speccopyright.html
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Status
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------
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- Approved by the SPIR-V Working Group: 2025-10-29
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- Approved by the Khronos Board of Promoters: 2025-12-12
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Version
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-------
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[width="40%",cols="25,25"]
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|========================================
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| Last Modified Date | 2025-10-13
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| Revision | 1
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|========================================
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Dependencies
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------------
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This extension is written against the SPIR-V Specification,
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Version 1.6, Revision 5, Unified.
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This extension requires SPIR-V 1.3.
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This extension interacts with SPV_KHR_physical_storage_buffer.
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Overview
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--------
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This extension adds support for vector types with an arbitrary positive number
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of components, and for a number of components taken from a specialization
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constant. These new vector types can be used with any instructions that act
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on vector types with an unrestricted number of components, but support a
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limited set of storage classes.
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This extension shares some functionality (*OpTypeVectorIdEXT*) with
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SPV_NV_cooperative_vector. It is intended to be a compilation target
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for GL_EXT_long_vector (GLSL) and
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https://github.com/microsoft/hlsl-specs/blob/main/proposals/0026-hlsl-long-vector-type.md
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(HLSL).
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Extension Name
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--------------
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To use this extension within a SPIR-V module, the following
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*OpExtension* must be present in the module:
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----
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OpExtension "SPV_EXT_long_vector"
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----
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Modifications to the SPIR-V Specification, Version 1.6
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------------------------------------------------------
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2.16 Validation Rules
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~~~~~~~~~~~~~~~~~~~~~
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==== Modify section 2.16.1. Universal Validation Rules:
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* Vector types with more than four components (or types containing them) can
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only be allocated in *Function*, *Private*, *Uniform*, *Workgroup*,
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*StorageBuffer*, *PhysicalStorageBuffer*, *PushConstant*,
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*ShaderRecordBufferKHR*, *CrossWorkgroup*, and *Generic* storage classes.
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* Matrix types must be parameterized only with *OpTypeVector* having 2, 3, or 4
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components.
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3.31 Capabilities
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~~~~~~~~~~~~~~~~~
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Modify Section 3.31, "Capability", adding these rows to the Capability table:
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--
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[options="header"]
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|====
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2+^| Capability ^| Implicitly Declares
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| 5425 | *LongVectorEXT* +
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Enables vector types with more than four components, one component, and
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*OpTypeVectorIdEXT*.
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|
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|====
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--
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3.56.6 Type-Declaration Instructions
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Modify *OpTypeVector* to allow a 'Component Count' of 1.
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[cols="1,1,3*3",width="100%"]
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|=====
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4+|[[OpTypeVectorIdEXT]]*OpTypeVectorIdEXT* +
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+
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Declare a new vector type with 'Component Count' components of the requested scalar type. +
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+
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'Component Type' is the type of each component in the resulting type. It must be a 'scalar type'.
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+
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'Component Count' is the number of components in the resulting type.
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'Component Count' must be a 'constant instruction' with scalar 32-bit 'integer type'.
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It is treated as an unsigned value and must be greater than zero. +
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+
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1+|Capability: +
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*LongVectorEXT*
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1+| 4 | 5288 | 'Result <id>' | '<id>' +
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'Component Type' | '<id>' +
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'Component Count'
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|=====
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3.56.12 Composite Instructions
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Modify *OpCompositeConstruct* to remove the following sentence:
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If constructing a vector, there must be at least two Constituent operands.
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Modify *OpVectorExtractDynamic*, *OpVectorInsertDynamic*, *OpVectorShuffle*,
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to change restrictions from "must be an *OpTypeVector*" or "must have a type *OpTypeVector*"
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to "must be/have a vector type".
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Issues
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------
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. How can a shader construct a vector with number of components defined by
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a specialization constant?
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+
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--
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*RESOLVED*: Use the instructions in SPV_EXT_replicated_composites to construct
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a vector with the same value replicated for all components.
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--
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. Which instructions support the new vector types?
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+
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--
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*RESOLVED*: Unless otherwise stated, any instruction that claims to support
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vector types and doesn't have a specific limitation on the number of components
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(for example, GLSL.std.450 *Cross* requires exactly three components) supports
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vectors with more than four components, one component, and vectors created using
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*OpTypeVectorIdEXT*. This includes GLSL.std.450 instructions.
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--
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. Should *OpVectorShuffle* support vectors with more than four components or
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*OpTypeVectorIdEXT*?
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+
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--
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*RESOLVED*: *OpVectorShuffle* has a similar problem to the other composite
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instructions where the number of operands must match the number of components,
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and this makes it awkward to work with *OpTypeVectorIdEXT*. Also, the high
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level language exposure of shuffle (swizzles) doesn't naturally extend to more
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components, though it is not hard to imagine a new intrinsic to expose this.
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Practically speaking, it's hard to draw a line for what not to support, and
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this could be useful in the future, so it is supported.
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--
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. Do we need to forbid spec-constant-sized vectors in explicitly laid out
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storage classes?
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+
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--
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*RESOLVED*: Vulkan has a restriction for spec-constant sized arrays, a similar
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restriction will apply to spec-constant-sized vectors.
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--
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Revision History
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----------------
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[cols="5,15,15,70"]
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[grid="rows"]
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[options="header"]
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|========================================
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|Rev|Date|Author|Changes
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|1|2025-10-13|Jeff Bolz|Initial revision of SPV_EXT_long_vector
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|========================================

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