Add documentation for RenderScript changes

[pirama]

Summary

• Document the new 'kernel' attribute
• Mention RenderScript support in the Release Notes.

[aaron.ballman]

include/clang/Basic/AttrDocs.td

2440

A little bit more information would be appreciated. I know you link to the RenderScript documentation, but there should be at least enough information here so that a reader has an idea what a kernel function is for render script.

[pirama]

Expand description of RenderScript kernel functions.

[pirama]

Rebase after submission of D21240.

[pirama]

Ping...

[aaron.ballman]

LGTM with a tiny wording nit.

include/clang/Basic/AttrDocs.td

2444

computations

[pirama]

computation -> computations.

docs/ReleaseNotes.rst

 
 TLS is enabled for Cygwin defaults to -femulated-tls.
 
 
 C Language Changes in Clang
 ---------------------------
 The -faltivec and -maltivec flags no longer silently include altivec.h on Power platforms.
 
+`RenderScript
+<https://developer.android.com/guide/topics/renderscript/compute.html>`_
+support added to the Frontend and enabled by the '-x renderscript' option or
+the '.rs' file extension.
+
 ...
 
 C11 Feature Support
 ^^^^^^^^^^^^^^^^^^^
 
 ...
 
 C++ Language Changes in Clang

include/clang/Basic/Attr.td

def OpenCLNoSVM : Attr {
   let Documentation = [OpenCLNoSVMDocs];
   let LangOpts = [OpenCL];
   let ASTNode = 0;
 }
 
 def RenderScriptKernel : Attr {
   let Spellings = [GNU<"kernel">];
   let Subjects = SubjectList<[Function]>;
-  let Documentation = [Undocumented];
+  let Documentation = [RenderScriptKernelAttributeDocs];
   let LangOpts = [RenderScript];
 }
 
 def Deprecated : InheritableAttr {
   let Spellings = [GCC<"deprecated">, Declspec<"deprecated">,
                    CXX11<"","deprecated", 201309>];
   let Args = [StringArgument<"Message", 1>,
               // An optional string argument that enables us to provide a

include/clang/Basic/AttrDocs.td

 }
 
 def LTOVisibilityDocs : Documentation {
   let Category = DocCatType;
   let Content = [{
 See :doc:`LTOVisibility`.
   }];
 }
+
+def RenderScriptKernelAttributeDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+``__attribute__((kernel))`` is used to mark a ``kernel`` function in
+RenderScript.
+
+In RenderScript, ``kernel`` functions are used to express data-parallel
+computations.  The RenderScript runtime efficiently parallelizes ``kernel``
+functions to run on computational resources such as multi-core CPUs and GPUs.
+See the RenderScript_ documentation for more information.
+
+.. _RenderScript: https://developer.android.com/guide/topics/renderscript/compute.html
+  }];
+}