[clang] [SYCL] The sycl_kernel_entry_point attribute. (PR #111389)

[Tom Honermann via cfe-commits]

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@@ -455,6 +455,64 @@ The SYCL kernel in the previous code sample meets these expectations.
   }];
 }
 
+def SYCLKernelEntryPointDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+The ``sycl_kernel_entry_point`` attribute specifies that a function definition
+defines a pattern for an offload kernel entry point function to be emitted when
+the source code is compiled with ``-fsycl`` for a device target. Such functions
+serve as the execution entry point for a SYCL run-time library to invoke a SYCL
+kernel on a device. The function's parameters define the parameters to the
+offload kernel.
+
+The attribute requires a single type argument that specifies a class type that
+meets the requirements for a SYCL kernel name as described in section 5.2,
+"Naming of kernels", of the SYCL 2020 specification. A unique kernel name type
+is required for each function declared with the attribute. The attribute may
+not first appear on a declaration that follows a definition of the function.
+
+The attribute appertains only to non-member functions and static member
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tahonermann wrote:

I reworded by moving the restriction on non-static member functions into the bullet list. I also added constructors and destructors.

Historically, lambdas would be prohibited by the restrictions against non-static member functions. We now have lambda expressions that produce a closure type with a static fiunction call operator. I think those should be ok.

https://github.com/llvm/llvm-project/pull/111389