Addfinal specifier to the classop (llvm#145977)

In some use cases of the `ClassOp`, eg MLGO, we would like to be able to declare the class as final. This specifier allows for that.

Author: Jaddyen

mlir/include/mlir/Dialect/EmitC/IR/EmitC.td

@@ -1618,10 +1618,20 @@ def EmitC_ClassOp
         return
       }
     }
+    // Class with a final speciferAdd commentMore actions
+    emitc.class final @modelClass {
+      emitc.field @fieldName0 : !emitc.array<1xf32> = {emitc.opaque = "input_tensor"}
+      emitc.func @execute() {
+        %0 = "emitc.constant"() <{value = 0 : index}> : () -> !emitc.size_t
+        %1 = get_field @fieldName0 : !emitc.array<1xf32>
+        %2 = subscript %1[%0] : (!emitc.array<1xf32>, !emitc.size_t) -> !emitc.lvalue<f32>
+        return
+      }
+    }
     ```
   }];
 
-  let arguments = (ins SymbolNameAttr:$sym_name);
+  let arguments = (ins SymbolNameAttr:$sym_name, UnitAttr:$final_specifier);
 
   let regions = (region AnyRegion:$body);
 
@@ -1632,7 +1642,8 @@ def EmitC_ClassOp
 
   let hasCustomAssemblyFormat = 1;
 
-  let assemblyFormat = [{ $sym_name attr-dict-with-keyword $body }];
+  let assemblyFormat =
+      [{ (`final` $final_specifier^)? $sym_name attr-dict-with-keyword $body }];
 }
 
 def EmitC_FieldOp : EmitC_Op<"field", [Symbol]> {

mlir/lib/Target/Cpp/TranslateToCpp.cpp

@@ -1000,8 +1000,10 @@ static LogicalResult printOperation(CppEmitter &emitter, ModuleOp moduleOp) {
 static LogicalResult printOperation(CppEmitter &emitter, ClassOp classOp) {
   CppEmitter::Scope classScope(emitter);
   raw_indented_ostream &os = emitter.ostream();
-  os << "class " << classOp.getSymName() << " {\n";
-  os << "public:\n";
+  os << "class " << classOp.getSymName();
+  if (classOp.getFinalSpecifier())
+    os << " final";
+  os << " {\n public:\n";
   os.indent();
 
   for (Operation &op : classOp) {

mlir/test/mlir-translate/emitc_classops.mlir

@@ -12,7 +12,32 @@ emitc.class @modelClass {
     }
 }
 
-// CHECK: class modelClass {
+// CHECK-LABEL: class modelClass {
+// CHECK-NEXT: public:
+// CHECK-NEXT:  float[1] fieldName0;
+// CHECK-NEXT:  float[1] fieldName1;
+// CHECK-NEXT:  void execute() {
+// CHECK-NEXT:    size_t v1 = 0;
+// CHECK-NEXT:    float[1] v2 = fieldName0;
+// CHECK-NEXT:    float[1] v3 = fieldName1;
+// CHECK-NEXT:    return;
+// CHECK-NEXT:  }
+// CHECK-EMPTY:
+// CHECK-NEXT: };
+
+emitc.class final @finalClass {
+    emitc.field @fieldName0 : !emitc.array<1xf32> 
+    emitc.field @fieldName1 : !emitc.array<1xf32> 
+    emitc.func @execute() {
+        %0 = "emitc.constant"() <{value = 0 : index}> : () -> !emitc.size_t
+        %1 = get_field @fieldName0 : !emitc.array<1xf32>
+        %2 = get_field @fieldName1 : !emitc.array<1xf32>
+        %3 = subscript %1[%0] : (!emitc.array<1xf32>, !emitc.size_t) -> !emitc.lvalue<f32>
+        return
+    }
+}
+
+// CHECK-LABEL: class finalClass final {
 // CHECK-NEXT: public:
 // CHECK-NEXT:  float[1] fieldName0;
 // CHECK-NEXT:  float[1] fieldName1;