[clang][Sema] Split SYCLKernel back into its own attribute (#162868)

Based on feedback from llvm/llvm-project#161905,
partially revert llvm/llvm-project#137882 so
that `sycl_kernel` is a separate attribute and not just a spelling of
`device_kernel`.

Signed-off-by: Sarnie, Nick <[email protected]>

Author: sarnex

clang/include/clang/Basic/Attr.td

@@ -1599,8 +1599,15 @@ def CUDAShared : InheritableAttr {
 }
 def : MutualExclusions<[CUDAConstant, CUDAShared, HIPManaged]>;
 
+def SYCLKernel : InheritableAttr {
+  let Spellings = [Clang<"sycl_kernel">];
+  let Subjects = SubjectList<[FunctionTmpl]>;
+  let LangOpts = [SYCLDevice];
+  let Documentation = [SYCLKernelDocs];
+}
+
 def DeviceKernel : DeclOrTypeAttr {
-  let Spellings = [Clang<"device_kernel">, Clang<"sycl_kernel">,
+  let Spellings = [Clang<"device_kernel">,
                    Clang<"nvptx_kernel">, Clang<"amdgpu_kernel">,
                    CustomKeyword<"__kernel">, CustomKeyword<"kernel">];
   let Documentation = [DeviceKernelDocs];
@@ -1624,15 +1631,6 @@ def DeviceKernel : DeclOrTypeAttr {
       if(!A) return false;
       return isNVPTXSpelling(*A);
     }
-    static inline bool isSYCLSpelling(const AttributeCommonInfo& A) {
-      return A.getAttributeSpellingListIndex() == GNU_sycl_kernel ||
-             A.getAttributeSpellingListIndex() == CXX11_clang_sycl_kernel ||
-             A.getAttributeSpellingListIndex() == C23_clang_sycl_kernel;
-    }
-    static inline bool isSYCLSpelling(const AttributeCommonInfo* A) {
-      if(!A) return false;
-      return isSYCLSpelling(*A);
-    }
     static inline bool isOpenCLSpelling(const AttributeCommonInfo& A) {
     // Tablegen trips underscores from spellings to build the spelling
     // list, but here we have the same spelling with unscores and without,

clang/include/clang/Basic/AttrDocs.td

@@ -396,13 +396,10 @@ any option of a multiversioned function is undefined.
   }];
 }
 
-def DeviceKernelDocs : Documentation {
+def SYCLKernelDocs : Documentation {
   let Category = DocCatFunction;
-  let Heading = "device_kernel, sycl_kernel, nvptx_kernel, amdgpu_kernel, "
-                "kernel, __kernel";
+  let Heading = "sycl_kernel";
   let Content = [{
-These attributes specify that the function represents a kernel for device offloading.
-The specific semantics depend on the offloading language, target, and attribute spelling.
 The ``sycl_kernel`` attribute specifies that a function template will be used
 to outline device code and to generate an OpenCL kernel.
 Here is a code example of the SYCL program, which demonstrates the compiler's
@@ -476,6 +473,21 @@ The SYCL kernel in the previous code sample meets these expectations.
   }];
 }
 
+def DeviceKernelDocs : Documentation {
+  let Category = DocCatFunction;
+  let Heading = "device_kernel, nvptx_kernel, amdgpu_kernel, "
+                "kernel, __kernel";
+  let Content = [{
+These attributes specify that the function represents a kernel for device offloading.
+The specific semantics depend on the offloading language, target, and attribute spelling.
+Here is a code example using the attribute to mark a function as a kernel:
+
+.. code-block:: c++
+
+  [[clang::device_kernel]] int foo(int x) { return ++x; }
+  }];
+}
+
 def SYCLExternalDocs : Documentation {
   let Category = DocCatFunction;
   let Heading = "sycl_external";

clang/lib/Sema/SemaDecl.cpp

@@ -20797,7 +20797,7 @@ Sema::FunctionEmissionStatus Sema::getEmissionStatus(const FunctionDecl *FD,
 
   // SYCL functions can be template, so we check if they have appropriate
   // attribute prior to checking if it is a template.
-  if (LangOpts.SYCLIsDevice && FD->hasAttr<DeviceKernelAttr>())
+  if (LangOpts.SYCLIsDevice && FD->hasAttr<SYCLKernelAttr>())
     return FunctionEmissionStatus::Emitted;
 
   // Templates are emitted when they're instantiated.

clang/lib/Sema/SemaDeclAttr.cpp

@@ -5204,16 +5204,7 @@ static void handleCallConvAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
 static void handleDeviceKernelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   const auto *FD = dyn_cast_or_null<FunctionDecl>(D);
   bool IsFunctionTemplate = FD && FD->getDescribedFunctionTemplate();
-  if (S.getLangOpts().SYCLIsDevice) {
-    if (!IsFunctionTemplate) {
-      S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type_str)
-          << AL << AL.isRegularKeywordAttribute() << "function templates";
-    } else {
-      S.SYCL().handleKernelAttr(D, AL);
-    }
-  } else if (DeviceKernelAttr::isSYCLSpelling(AL)) {
-    S.Diag(AL.getLoc(), diag::warn_attribute_ignored) << AL;
-  } else if (S.getASTContext().getTargetInfo().getTriple().isNVPTX()) {
+  if (S.getASTContext().getTargetInfo().getTriple().isNVPTX()) {
     handleGlobalAttr(S, D, AL);
   } else {
     // OpenCL C++ will throw a more specific error.
@@ -7100,6 +7091,9 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
   case ParsedAttr::AT_EnumExtensibility:
     handleEnumExtensibilityAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_SYCLKernel:
+    S.SYCL().handleKernelAttr(D, AL);
+    break;
   case ParsedAttr::AT_SYCLExternal:
     handleSimpleAttribute<SYCLExternalAttr>(S, D, AL);
     break;

clang/lib/Sema/SemaSYCL.cpp

@@ -199,7 +199,7 @@ void SemaSYCL::handleKernelAttr(Decl *D, const ParsedAttr &AL) {
     return;
   }
 
-  handleSimpleAttribute<DeviceKernelAttr>(*this, D, AL);
+  handleSimpleAttribute<SYCLKernelAttr>(*this, D, AL);
 }
 
 void SemaSYCL::handleKernelEntryPointAttr(Decl *D, const ParsedAttr &AL) {

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -710,9 +710,9 @@ static void instantiateDependentAMDGPUMaxNumWorkGroupsAttr(
 // This doesn't take any template parameters, but we have a custom action that
 // needs to happen when the kernel itself is instantiated. We need to run the
 // ItaniumMangler to mark the names required to name this kernel.
-static void instantiateDependentDeviceKernelAttr(
+static void instantiateDependentSYCLKernelAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
-    const DeviceKernelAttr &Attr, Decl *New) {
+    const SYCLKernelAttr &Attr, Decl *New) {
   New->addAttr(Attr.clone(S.getASTContext()));
 }
 
@@ -966,8 +966,8 @@ void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
       continue;
     }
 
-    if (auto *A = dyn_cast<DeviceKernelAttr>(TmplAttr)) {
-      instantiateDependentDeviceKernelAttr(*this, TemplateArgs, *A, New);
+    if (auto *A = dyn_cast<SYCLKernelAttr>(TmplAttr)) {
+      instantiateDependentSYCLKernelAttr(*this, TemplateArgs, *A, New);
       continue;
     }
 

clang/lib/Sema/SemaType.cpp

@@ -3780,12 +3780,10 @@ static CallingConv getCCForDeclaratorChunk(
       }
     }
   }
-  if (!S.getLangOpts().isSYCL()) {
-    for (const ParsedAttr &AL : D.getDeclSpec().getAttributes()) {
-      if (AL.getKind() == ParsedAttr::AT_DeviceKernel) {
-        CC = CC_DeviceKernel;
-        break;
-      }
+  for (const ParsedAttr &AL : D.getDeclSpec().getAttributes()) {
+    if (AL.getKind() == ParsedAttr::AT_DeviceKernel) {
+      CC = CC_DeviceKernel;
+      break;
     }
   }
   return CC;