[OpenCL] Release 3.9 notes

[Anastasia]

Summary

Release notes for OpenCL in Clang

[hans]

lgtm!

Please commit to https://llvm.org/svn/llvm-project/cfe/branches/release_39 or let me know if you'd prefer me to do it.

docs/ReleaseNotes.rst

206

very minor nit: there are two spaces after "diagnostics"

[Anastasia]

Thanks! Is there a way to check the doc before committing? I am not sure how to make the html generated out of this.

[hans]

In D23452#514110, @Anastasia wrote:

Thanks! Is there a way to check the doc before committing? I am not sure how to make the html generated out of this.

I build the docs like this:

cmake -GNinja -DLLVM_ENABLE_SPHINX=ON -DLLVM_BUILD_DOCS=ON ../llvm.src
ninja sphinx

[Anastasia]

Thanks! Committed in r278677.

[Anastasia]

@hans, I have committed one minor addition to OpenCL notes (r279224), which is important enough to include

Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst	(revision 279176)
  +++ docs/ReleaseNotes.rst	(working copy)
  @@ -163,6 +163,8 @@
   features have been completed since the previous release:
   
   - Pipe builtin functions (s6.13.16.2-4).
  +- Dynamic parallelism support via the ``enqueue_kernel`` Clang builtin function,
  +  as well as the kernel query functions from s6.13.17.6. 
   - Address space conversion functions ``to_{global/local/private}``.
   - ``nosvm`` attribute support.
   - Improved diagnostic and generation of Clang Blocks used in OpenCL kernel code.

I hope it's not a problem.

docs/ReleaseNotes.rst

 OpenCL C Language Changes in Clang
 ----------------------------------
 
-...
+Clang now has support for all OpenCL 2.0 features.  In particular, the following
+features have been completed since the previous release:
+
+- Pipe builtin functions (s6.13.16.2-4).
+- Address space conversion functions ``to_{global/local/private}``.
+- ``nosvm`` attribute support.
+- Improved diagnostic and generation of Clang Blocks used in OpenCL kernel code.
+- ``opencl_unroll_hint`` pragma.
+
+Several miscellaneous improvements have been made:
+
+- Supported extensions are now part of the target representation to give correct
+  diagnostics  for unsupported target features during compilation. For example,
+  when compiling for a target that does not support the double precision
+  floating point extension, Clang will give an error when encountering the
+  ``cl_khr_fp64 pragma``. Several missing extensions were added covering up to
+  and including OpenCL 2.0.
+- Clang now comes with the OpenCL standard headers declaring builtin types and
+  functions up to and including OpenCL 2.0 in ``lib/Headers/opencl-c.h``. By
+  default, Clang will not include this header. It can be included either using
+  the regular ``-I<path to header location>`` directive or (if the default one
+  from installation is to be used) using the ``-finclude-default-header``
+  frontend flag.
+  Example:
+    ``echo "bool is_wg_uniform(int i){return get_enqueued_local_size(i)==get_local_size(i);}" > test.cl``
+    ``clang -cc1 -finclude-default-header -cl-std=CL2.0 test.cl``
+  All builtin function declarations from OpenCL 2.0 will be automatically
+  visible in test.cl.
+- Image types have been improved with better diagnostics for access qualifiers.
+  Images with one access qualifier type cannot be used in declarations for
+  another. Also qualifiers are now propagated from the frontend down to
+  libraries and backends.
+- Diagnostic improvements for OpenCL types, address spaces and vectors.
+- Half type literal support has been added. For example, ``1.0h`` represents a
+  floating point literal in half precision, i.e., the value ``0xH3C00``.
+- The Clang driver now accepts OpenCL compiler options ``-cl-*`` (following the
+  OpenCL Spec v1.1-1.2 s5.8). For example, the ``-cl-std=CL1.2`` option from the
+  spec enables compilation for OpenCL 1.2, or ``-cl-mad-enable`` will enable
+  fusing multiply-and-add operations.
+- Clang now uses function metadata instead of module metadata to propagate
+  information related to OpenCL kernels e.g. kernel argument information.
 
 OpenMP Support in Clang
 ----------------------------------