[SYCL][DOC] Move deprecated extensions

Move these deprecated extension specifications to the "supported"
directory.  We decided to keep the deprecated extensions in this
directory because:

* Deprecated extensions are still supported.
* We want to avoid breaking hyperlinks to an extension when
  transitioning from supported to deprecated.

Author: gmlueck

sycl/ReleaseNotes.md

@@ -264,7 +264,7 @@ Release notes for commit range 6a49170027fb..962909fe9e78
  - Implemented generation of compiler report for kernel arguments [201f902]
  - Implemented SYCL 2020 `[[reqd_sub_group_size]]` attribute [347e41c]
  - Implemented support for `[[intel::named_sub_group_size(primary)]]` attribute
-   from [sub-group extension](doc/extensions/SubGroup/SYCL_INTEL_sub_group.asciidoc#attributes)
+   from [sub-group extension](doc/extensions/supported/SYCL_EXT_ONEAPI_SUB_GROUP.asciidoc#attributes)
    [347e41c]
  - Implemented SYCL 2020 interoperability API [e6733e4]
  - Added [group sorting algorithm](doc/extensions/experimental/SYCL_EXT_ONEAPI_GROUP_SORT.asciidoc)
@@ -591,7 +591,7 @@ Release notes for commit range 2ffafb95f887..6a49170027fb
  - Improved design document for program cache [ed4b4c4]
  - Updated compiler options [description](doc/UsersManual.md) [e56e576]
  - Updated
-   [SYCL_INTEL_sub_group]doc/extensions/SubGroup/SYCL_INTEL_sub_group.asciidoc
+   [SYCL_INTEL_sub_group](doc/extensions/supported/SYCL_EXT_ONEAPI_SUB_GROUP.asciidoc)
    extension document to use `automatic` instead of `auto` [c4d08f5]
 
 ## Bug fixes
@@ -1358,7 +1358,7 @@ Release notes for the commit range 75b3dc2..5976ff0
   - Added [Use Pinned Host Memory Property extension](doc/extensions/supported/SYCL_EXT_ONEAPI_USE_PINNED_HOST_MEMORY_PROPERTY.asciidoc) specification [e5ea144]
   - Updated the [SYCL_INTEL_extended_atomics extension](doc/extensions/supported/SYCL_EXT_ONEAPI_EXTENDED_ATOMICS.asciidoc)
     to describe `sycl::intel::atomic_accessor` [4968e7c]
-  - The [SYCL_INTEL_sub_group extension](doc/extensions/SubGroup/SYCL_INTEL_sub_group.asciidoc)
+  - The [SYCL_INTEL_sub_group extension](doc/extensions/supported/SYCL_EXT_ONEAPI_SUB_GROUP.asciidoc)
     document has been updated [067536e]
   - Added [FPGA lsu extension](sycl/doc/extensions/supported/SYCL_EXT_INTEL_FPGA_LSU.md)
     document [2c2b5f2]
@@ -1485,7 +1485,7 @@ Release notes for the commit range ba404be..24726df
 
 ### SYCL Library
   - Updated the implementation to align with changes in
-    [SubGroup extension](doc/extensions/SubGroup/SYCL_INTEL_sub_group.asciidoc) [9d4c284]
+    [SubGroup extension](doc/extensions/supported/SYCL_EXT_ONEAPI_SUB_GROUP.asciidoc) [9d4c284]
   - `sycl::ordered_queue` class has been removed [875347a]
   - Added support of rounding modes for floating and integer types in
     `sycl::vec::convert` [096d0a0]
@@ -1517,7 +1517,7 @@ Release notes for the commit range ba404be..24726df
   - OpenCL CPU runtime installation instructions in
     [GetStartedGuide](doc/GetStartedGuide.md) and the installation script have
     been improved [9aa5029]
-  - The [SYCL_INTEL_sub_group extension document](doc/extensions/SubGroup/SYCL_INTEL_sub_group.asciidoc)
+  - The [SYCL_INTEL_sub_group extension document](doc/extensions/supported/SYCL_EXT_ONEAPI_SUB_GROUP.asciidoc)
     has been updated [010f112]
   - Render user API classes on a dedicated page [98b6ee4]
 
@@ -1599,7 +1599,7 @@ Release notes for the commit range ba404be..24726df
 Release notes for the commit range ba404be..67d3d9e
 
 ## New features
-  - Implemented [reduction extension](doc/extensions/Reduction/Reduction.md)
+  - Implemented [reduction extension](doc/extensions/supported/SYCL_EXT_ONEAPI_ND_RANGE_REDUCTIONS.md)
     for `sycl::handler::parallel_for` accepting a `sycl::nd_range` object
     [bb73d926] [04a360a] [05625f1]
   - XPTI instrumentation has been added to the runtime to capture semantic and
@@ -1678,7 +1678,7 @@ Release notes for the commit range ba404be..67d3d9e
   - [Contribution guidelines](../CONTRIBUTING.md) were simplified, now sign-off
     line is not required [7886fd8]
   - Added missing constructors and member functions in
-    [reduction extension proposal](doc/extensions/Reduction/Reduction.md)
+    [reduction extension proposal](doc/extensions/supported/SYCL_EXT_ONEAPI_ND_RANGE_REDUCTIONS.md)
     [f695479]
   - Published [parallel_for simplification extension](doc/extensions/ParallelForSimpification/SYCL_INTEL_parallel_for_simplification.asciidoc) [856a777]
   - Added memory scope to [ExtendedAtomics extension](doc/extensions/supported/SYCL_EXT_ONEAPI_EXTENDED_ATOMICS.asciidoc) [f8e11e0]
@@ -1752,7 +1752,7 @@ Release notes for the commit range e8f1f29..ba404be
 ## New features
   - Initial CUDA backend support [7a9a425]
   - [SYCL][FPGA] Implement IO pipes interface [c900248]
-  - Added the implementation of [GroupAlgorithms extension](doc/extensions/GroupAlgorithms/SYCL_INTEL_group_algorithms.asciidoc)
+  - Added the implementation of [GroupAlgorithms extension](doc/extensions/supported/SYCL_EXT_ONEAPI_GROUP_ALGORITHMS.asciidoc)
     [8bfa107]
   - Added a partial implementation of [sub group algorithms extension](doc/extensions/SubGroupAlgorithms/SYCL_INTEL_sub_group_algorithms.asciidoc)
     [017af4e]
@@ -1825,7 +1825,7 @@ Release notes for the commit range e8f1f29..ba404be
     [ce53521]
   - Deprecated SubGroupNDRange extension [d9b178f]
   - Added extension for base sub-group class:
-    [SubGroup](doc/extensions/SubGroup/SYCL_INTEL_sub_group.asciidoc) [d9b178f]
+    [SubGroup](doc/extensions/supported/SYCL_EXT_ONEAPI_SUB_GROUP.asciidoc) [d9b178f]
   - Added extension for functions operating on sub-groups:
     [SubGroupAlgorithms](doc/extensions/SubGroupAlgorithms/SYCL_INTEL_sub_group_algorithms.asciidoc)
     [d9b178f]

sycl/doc/extensions/GroupAlgorithms/README.md

@@ -7,14 +7,11 @@ DPC++ extensions status:
 
 |  Extension  |    Status   |   Comment   |
 |-------------|:------------|:------------|
-| [SYCL_INTEL_group_algorithms](GroupAlgorithms/SYCL_INTEL_group_algorithms.asciidoc)                                         | Deprecated                                | |
 | [GroupMask](GroupMask/GroupMask.asciidoc)                                                                                   | Proposal                                  | |
-| [Reductions for ND-Range Parallelism](Reduction/Reduction.md)                                                               | Partially supported(OpenCL: CPU, GPU; CUDA) | Not supported: multiple reduction vars, multi-dimensional reduction vars |
 | [SPV_INTEL_function_pointers](SPIRV/SPV_INTEL_function_pointers.asciidoc)                                                   | Supported(OpenCL: CPU, GPU; HOST)         | |
 | [SPV_INTEL_inline_assembly](SPIRV/SPV_INTEL_inline_assembly.asciidoc)                                                       | Supported(OpenCL: GPU)                    | |
 | [SYCL_INTEL_static_local_memory_query](StaticLocalMemoryQuery/SYCL_INTEL_static_local_memory_query.asciidoc)                | Proposal                                  | |
 | [Sub-groups for NDRange Parallelism](SubGroupNDRange/SubGroupNDRange.md)                                                    | Deprecated(OpenCL: CPU, GPU)              | |
-| [Sub-groups](SubGroup/SYCL_INTEL_sub_group.asciidoc)                                                                        | Deprecated                                | |
 | [Property List](PropertyList/SYCL_EXT_ONEAPI_property_list.asciidoc)                                                        | Proposal                                  | |
 | [DiscardQueueEvents](DiscardQueueEvents/SYCL_EXT_ONEAPI_DISCARD_QUEUE_EVENTS.asciidoc) | Proposal | |
 

sycl/doc/extensions/README.md

@@ -8,7 +8,7 @@
 
 There are 2 specifications of the reduction feature and both are still actual:
 
-* `sycl::ext::oneapi::reduction` is described in [this document](https://github.com/intel/llvm/blob/sycl/sycl/doc/extensions/Reduction/Reduction.md). This extension is deprecated, and was created as part of a pathfinding/prototyping work before it was added to SYCL 2020 standard.
+* `sycl::ext::oneapi::reduction` is described in [this document](../supported/SYCL_EXT_ONEAPI_ND_RANGE_REDUCTIONS.md). This extension is deprecated, and was created as part of a pathfinding/prototyping work before it was added to SYCL 2020 standard.
 
 * `sycl::reduction` is described in [SYCL 2020 standard](https://www.khronos.org/registry/SYCL/specs/sycl-2020/html/sycl-2020.html#sec:reduction).