[acc][flang] Use SymbolRefAttr for func_name in ACC routine

Changed the type of the `func_name` attribute from SymbolNameAttr to SymbolRefAttr.
SymbolNameAttr is typically used when defining a symbol (e.g., `sym_name`), while
SymbolRefAttr is appropriate for referencing existing operations. This change ensures
that MLIR can correctly track the link to the referenced `func.func` operation.

Author: Delaram Talaashrafi

flang/lib/Lower/OpenACC.cpp

@@ -4561,7 +4561,8 @@ void createOpenACCRoutineConstruct(
     llvm::SmallVector<mlir::Attribute> &vectorDeviceTypes) {
 
   for (auto routineOp : mod.getOps<mlir::acc::RoutineOp>()) {
-    if (routineOp.getFuncName().str().compare(funcName) == 0) {
+    if (routineOp.getFuncName().getLeafReference().str().compare(funcName) ==
+        0) {
       // If the routine is already specified with the same clauses, just skip
       // the operation creation.
       if (compareDeviceTypeInfo(routineOp, bindNames, bindNameDeviceTypes,
@@ -4579,7 +4580,9 @@ void createOpenACCRoutineConstruct(
   mlir::OpBuilder modBuilder(mod.getBodyRegion());
   fir::FirOpBuilder &builder = converter.getFirOpBuilder();
   modBuilder.create<mlir::acc::RoutineOp>(
-      loc, routineOpStr, funcName, getArrayAttrOrNull(builder, bindNames),
+      loc, routineOpStr,
+      mlir::SymbolRefAttr::get(builder.getContext(), funcName),
+      getArrayAttrOrNull(builder, bindNames),
       getArrayAttrOrNull(builder, bindNameDeviceTypes),
       getArrayAttrOrNull(builder, workerDeviceTypes),
       getArrayAttrOrNull(builder, vectorDeviceTypes),

mlir/include/mlir/Dialect/OpenACC/OpenACCOps.td

@@ -2771,18 +2771,15 @@ def OpenACC_RoutineOp : OpenACC_Op<"routine", [IsolatedFromAbove]> {
     must be modified as well.
   }];
 
-  let arguments = (ins SymbolNameAttr:$sym_name,
-                       SymbolNameAttr:$func_name,
-                       OptionalAttr<StrArrayAttr>:$bindName,
-                       OptionalAttr<DeviceTypeArrayAttr>:$bindNameDeviceType,
-                       OptionalAttr<DeviceTypeArrayAttr>:$worker,
-                       OptionalAttr<DeviceTypeArrayAttr>:$vector,
-                       OptionalAttr<DeviceTypeArrayAttr>:$seq,
-                       UnitAttr:$nohost,
-                       UnitAttr:$implicit,
-                       OptionalAttr<DeviceTypeArrayAttr>:$gang,
-                       OptionalAttr<I64ArrayAttr>:$gangDim,
-                       OptionalAttr<DeviceTypeArrayAttr>:$gangDimDeviceType);
+  let arguments = (ins SymbolNameAttr:$sym_name, SymbolRefAttr:$func_name,
+      OptionalAttr<StrArrayAttr>:$bindName,
+      OptionalAttr<DeviceTypeArrayAttr>:$bindNameDeviceType,
+      OptionalAttr<DeviceTypeArrayAttr>:$worker,
+      OptionalAttr<DeviceTypeArrayAttr>:$vector,
+      OptionalAttr<DeviceTypeArrayAttr>:$seq, UnitAttr:$nohost,
+      UnitAttr:$implicit, OptionalAttr<DeviceTypeArrayAttr>:$gang,
+      OptionalAttr<I64ArrayAttr>:$gangDim,
+      OptionalAttr<DeviceTypeArrayAttr>:$gangDimDeviceType);
 
   let extraClassDeclaration = [{
     static StringRef getGangDimKeyword() { return "dim"; }