[clang] [llvm] [clang] Simplify device kernel attributes (PR #137882)

[Nick Sarnie via llvm-commits]

================
@@ -1538,11 +1533,32 @@ def CUDAShared : InheritableAttr {
 }
 def : MutualExclusions<[CUDAConstant, CUDAShared, HIPManaged]>;
 
-def SYCLKernel : InheritableAttr {
-  let Spellings = [Clang<"sycl_kernel">];
-  let Subjects = SubjectList<[FunctionTmpl]>;
-  let LangOpts = [SYCLDevice];
+def DeviceKernel : DeclOrTypeAttr {
+  let Spellings = [Clang<"device_kernel">, Clang<"sycl_kernel">,
+                   Clang<"nvptx_kernel">, Clang<"amdgpu_kernel">,
+                   CustomKeyword<"__kernel">, CustomKeyword<"kernel">];
   let Documentation = [SYCLKernelDocs];
----------------
sarnex wrote:

I made an attempt in the latest commit I just pushed [here](https://github.com/llvm/llvm-project/pull/137882/commits/421950d2e40012569993e911a635f86ce4bfd611). SYCL was the only documented one previously and I didn't want to be stucking having to document all the others, so hopefully the way I did it makes sense.

https://github.com/llvm/llvm-project/pull/137882