[SYCL] Add clang support for FPGA kernel attribute scheduler_target_fmax_mhz

Author: schittir

clang/include/clang/Basic/Attr.td

@@ -1225,6 +1225,15 @@ def SYCLIntelNumSimdWorkItems : InheritableAttr {
   let PragmaAttributeSupport = 0;
 }
 
+def SYCLIntelSchedulerTargetFmaxMhz : InheritableAttr {
+  let Spellings = [CXX11<"intelfpga","scheduler_target_fmax_mhz">];
+  let Args = [UnsignedArgument<"Number">];
+  let LangOpts = [SYCLIsDevice, SYCLIsHost];
+  let Subjects = SubjectList<[Function], ErrorDiag>;
+  let Documentation = [SYCLIntelSchedulerTargetFmaxMhzAttrDocs];
+  let PragmaAttributeSupport = 0;
+}
+
 def SYCLIntelMaxWorkGroupSize : InheritableAttr {
   let Spellings = [CXX11<"intelfpga","max_work_group_size">];
   let Args = [UnsignedArgument<"XDim">,

clang/include/clang/Basic/AttrDocs.td

@@ -2197,6 +2197,17 @@ device kernel, the attribute is ignored and it is not propagated to a kernel.
   }];
 }
 
+def SYCLIntelSchedulerTargetFmaxMhzAttrDocs : Documentation {
+  let Category = DocCatFunction;
+  let Heading = "scheduler_target_fmax_mhz (IntelFPGA)";
+  let Content = [{
+Applies to a device function/lambda function. Indicates that the kernel should
+be pipelined so as to achieve the specified target clock frequency (Fmax) of N
+MHz. The argument N may be a template parameter. This attribute should be
+ignored for the FPGA emulator device.
+  }];
+}
+
 def SYCLIntelNoGlobalWorkOffsetAttrDocs : Documentation {
   let Category = DocCatFunction;
   let Heading = "no_global_work_offset (IntelFPGA)";

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -639,6 +639,14 @@ void CodeGenFunction::EmitOpenCLKernelMetadata(const FunctionDecl *FD,
                     llvm::MDNode::get(Context, AttrMDArgs));
   }
 
+  if (const SYCLIntelSchedulerTargetFmaxMhzAttr *A =
+      FD->getAttr<SYCLIntelSchedulerTargetFmaxMhzAttr>()) {
+    llvm::Metadata *AttrMDArgs[] = {
+        llvm::ConstantAsMetadata::get(Builder.getInt32(A->getNumber()))};
+    Fn->setMetadata("scheduler_target_fmax_mhz",
+                    llvm::MDNode::get(Context, AttrMDArgs));
+  }
+
   if (const SYCLIntelMaxWorkGroupSizeAttr *A =
       FD->getAttr<SYCLIntelMaxWorkGroupSizeAttr>()) {
     llvm::Metadata *AttrMDArgs[] = {