[SYCL][Bindless][Doc] Introduce SPIR-V spec for enabling bindless images on Intel devices (#12927)

Create a new extension to enable SPIR-V to support handle conversion to
image and sampler types for the bindless images extension.

Author: DBDuncan

sycl/doc/design/spirv-extensions/SPV_INTEL_bindless_images.asciidoc

@@ -0,0 +1,169 @@
+:capability_token: 6528
+:handle_to_image_token: 6529
+:handle_to_sampler_token: 6530
+
+SPV_INTEL_bindless_images
+=========================
+
+== Name Strings
+
+SPV_INTEL_bindless_images
+
+== Contact
+
+To report problems with this extension, please open a new issue at:
+
+<https://github.com/intel/llvm/issues>
+
+== Contributors
+
+- Duncan Brawley, Codeplay
+- Przemek Malon, Codeplay
+- Peter Žužek, Codeplay
+- Chedy Najjar, Codeplay
+- Sean Stirling, Codeplay
+- Isaac Ault, Codeplay
+- Victor Lomuller, Codeplay
+
+== Notice
+
+Copyright © Codeplay Software Limited. All rights reserved.
+
+== Status
+
+In Development
+
+== Version
+
+[width="40%",cols="25,25"]
+|========================================
+| Last Modified Date | 2024-03-25
+| Revision           | 6
+|========================================
+
+== Dependencies
+
+This extension is written against the SPIR-V Specification,
+Version 1.6 Revision 1.
+
+This extension requires SPIR-V 1.0.
+
+== Overview
+
+This extension adds support for bindless images.
+This is done by adding support for SPIR-V to convert unsigned integer handles to
+images/samplers.
+
+Bindless images are a feature that provides flexibility on how images are
+accessed and used, such as removing limitations on how many images can be
+accessed as well as potentially improving performance.
+This is an improvement on the legacy bound images model which is a holdover from
+binding slots in hardware which used to be limited in number.
+
+== Extension Name
+
+To use this extension within a SPIR-V module, the following *OpExtension* must
+be present in the module:
+
+----
+OpExtension "SPV_INTEL_bindless_images"
+----
+
+== New Capabilities
+
+This extension introduces a new capability:
+
+----
+BindlessImagesINTEL
+----
+
+== New Instructions
+
+Instructions added under *BindlessImagesINTEL* capability.
+
+----
+OpConvertHandleToImageINTEL
+OpConvertHandleToSamplerINTEL
+----
+
+== Token Number Assignments
+
+--
+[width="40%"]
+[cols="70%,30%"]
+[grid="rows"]
+|====
+|BindlessImagesINTEL                |{capability_token}
+|OpConvertHandleToImageINTEL        |{handle_to_image_token}
+|OpConvertHandleToSamplerINTEL      |{handle_to_sampler_token}
+|====
+--
+
+== Modifications to the SPIR-V Specification, Version 1.6, Revision 2
+
+Modify Section 3.49.10, Image Instructions, adding to the end of the list of
+instructions:
+
+[cols="2*1,3*2"]
+|======
+5+|[[OpConvertHandleToImageINTEL]]*OpConvertHandleToImageINTEL* +
+ +
+Converts an unsigned integer pointed by _Operand_ to image type.
+
+Unsigned integer is either a 32 or 64 bit unsigned integer.
+Depending on if the addressing model is set to *Physical32* or *Physical64*.
+
+_Result type_ must be an `OpTypeImage`.
+
+| 4 | {handle_to_image_token} | '<id> Result Type' | 'Result <id>' |
+'<id> Operand'
+|======
+
+[cols="2*1,3*2"]
+|======
+5+|[[OpConvertHandleToSamplerINTEL]]*OpConvertHandleToSamplerINTEL* +
+ +
+Converts an unsigned integer pointed by _Operand_ to sampler type.
+
+Unsigned integer is either a 32 or 64 bit unsigned integer.
+Depending on if the addressing model is set to *Physical32* or *Physical64*.
+
+_Result type_ must be an `OpTypeSampler`.
+
+| 4 | {handle_to_sampler_token} | '<id> Result Type' | 'Result <id>' |
+'<id> Operand'
+|======
+
+Modify Section 3.31, Capability, adding row to the capability table:
+
+[width="40%"]
+[options="header"]
+|====
+2+^| Capability ^| Implicitly Declares
+| {capability_token} | BindlessImagesINTEL |
+|====
+
+
+== Issues
+
+None Yet.
+
+== Revision History
+
+[cols="5,15,15,70"]
+[grid="rows"]
+[options="header"]
+|========================================
+|Rev|Date|Author|Changes
+|1|2023-03-23|Duncan Brawley|*Initial public release*
+|2|2023-03-30|Duncan Brawley| Updated token assignments
+|3|2023-05-29|Duncan Brawley| Updated token assignments and fix capitalization
+|4|2023-06-13|Duncan Brawley| Remove need for OpHandleAddressingModeINTEL 
+                              instruction
+|5|2024-02-23|Duncan Brawley| Remove OpConvertHandleToSampledImageINTEL
+                              instruction and clarify return types
+|6|2024-03-25|Duncan Brawley| Wording/formatting improvements, clarify sections
+                              edited, make capability addition explicit and
+                              substitute instruction numbers            
+|========================================
+