[SYCL] Implement OpenCL kernel function generation

clang/include/clang/Sema/Sema.h

@@ -11632,6 +11632,19 @@ class Sema final {
     ConstructorDestructor,
     BuiltinFunction
   };
+
+private:
+  /// Contains generated OpenCL kernel functions for SYCL.
+  SmallVector<Decl *, 4> SYCLKernels;
+
+public:
+  void addSYCLKernel(Decl *D) { SYCLKernels.push_back(D); }
+  /// Access to SYCL kernels.
+  SmallVectorImpl<Decl *> &getSYCLKernels() { return SYCLKernels; }
+
+  /// Constructs an OpenCL kernel using the KernelCaller function and adds it to
+  /// the SYCL device code.
+  void constructOpenCLKernel(FunctionDecl *KernelCallerFunc, MangleContext &MC);
 };
 
 /// RAII object that enters a new expression evaluation context.

clang/lib/AST/ASTContext.cpp

@@ -10023,6 +10023,10 @@ bool ASTContext::DeclMustBeEmitted(const Decl *D) {
   if (D->hasAttr<AliasAttr>() || D->hasAttr<UsedAttr>())
     return true;
 
+  // If SYCL, only kernels are required.
+  if (LangOpts.SYCLIsDevice && !(D->hasAttr<OpenCLKernelAttr>()))
+    return false;
+
   if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
     // Forward declarations aren't required.
     if (!FD->doesThisDeclarationHaveABody())

clang/lib/CodeGen/CodeGenModule.cpp

@@ -2474,6 +2474,12 @@ void CodeGenModule::EmitGlobal(GlobalDecl GD) {
     }
   }
 
+  if (LangOpts.SYCLIsDevice && Global->hasAttr<OpenCLKernelAttr>() &&
+      MustBeEmitted(Global)) {
+    addDeferredDeclToEmit(GD);
+    return;
+  }
+
   // Ignore declarations, they will be emitted on their first use.
   if (const auto *FD = dyn_cast<FunctionDecl>(Global)) {
     // Forward declarations are emitted lazily on first use.

clang/lib/Parse/ParseAST.cpp

@@ -168,6 +168,10 @@ void clang::ParseAST(Sema &S, bool PrintStats, bool SkipFunctionBodies) {
   for (Decl *D : S.WeakTopLevelDecls())
     Consumer->HandleTopLevelDecl(DeclGroupRef(D));
 
+  if (S.getLangOpts().SYCLIsDevice)
+    for (Decl *D : S.getSYCLKernels())
+      Consumer->HandleTopLevelDecl(DeclGroupRef(D));
+
   Consumer->HandleTranslationUnit(S.getASTContext());
 
   // Finalize the template instantiation observer chain.

clang/lib/Sema/CMakeLists.txt

@@ -57,6 +57,7 @@ add_clang_library(clangSema
   SemaStmt.cpp
   SemaStmtAsm.cpp
   SemaStmtAttr.cpp
+  SemaSYCL.cpp
   SemaTemplate.cpp
   SemaTemplateDeduction.cpp
   SemaTemplateInstantiate.cpp