[mlir][emitc] Add verification for the emitc.get_field op (#152577)

This MR adds a `verifier` for the `emitc.get_field` op. 
- The `verifier` checks that the `emitc.get_field` operation is nested
  inside an `emitc.class` op.
- Additionally, appropriate tests for erroneous cases were added for
  class-related operations in `invalid_ops.mlir`.

Author: EtoAndruwa

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

@@ -1697,6 +1697,7 @@ def EmitC_GetFieldOp
   let arguments = (ins FlatSymbolRefAttr:$field_name);
   let results = (outs EmitCType:$result);
   let assemblyFormat = "$field_name `:` type($result) attr-dict";
+  let hasVerifier = 1;
 }
 
 #endif // MLIR_DIALECT_EMITC_IR_EMITC

mlir/lib/Dialect/EmitC/IR/EmitC.cpp

@@ -1395,6 +1395,7 @@ void FileOp::build(OpBuilder &builder, OperationState &state, StringRef id) {
 //===----------------------------------------------------------------------===//
 // FieldOp
 //===----------------------------------------------------------------------===//
+
 static void printEmitCFieldOpTypeAndInitialValue(OpAsmPrinter &p, FieldOp op,
                                                  TypeAttr type,
                                                  Attribute initialValue) {
@@ -1452,6 +1453,15 @@ LogicalResult FieldOp::verify() {
 //===----------------------------------------------------------------------===//
 // GetFieldOp
 //===----------------------------------------------------------------------===//
+
+LogicalResult GetFieldOp::verify() {
+  auto parentClassOp = getOperation()->getParentOfType<emitc::ClassOp>();
+  if (!parentClassOp.getOperation())
+    return emitOpError(" must be nested within an emitc.class operation");
+
+  return success();
+}
+
 LogicalResult GetFieldOp::verifySymbolUses(SymbolTableCollection &symbolTable) {
   mlir::FlatSymbolRefAttr fieldNameAttr = getFieldNameAttr();
   FieldOp fieldOp =

mlir/test/Dialect/EmitC/invalid_ops.mlir

@@ -676,3 +676,35 @@ func.func @test_verbatim(%arg0 : !emitc.ptr<i32>, %arg1 : i32) {
   emitc.verbatim "{a} " args %arg0, %arg1 : !emitc.ptr<i32>, i32
   return
 }
+
+// -----
+
+// expected-error @+1 {{'emitc.field' op field must be nested within an emitc.class operation}}
+emitc.field @testField : !emitc.array<1xf32>
+
+// -----
+
+// expected-error @+1 {{'emitc.get_field' op  must be nested within an emitc.class operation}}
+%1 = emitc.get_field @testField : !emitc.array<1xf32>
+
+// -----
+
+emitc.func @testMethod() {
+  %0 = "emitc.constant"() <{value = 0 : index}> : () -> !emitc.size_t
+  // expected-error @+1 {{'emitc.get_field' op  must be nested within an emitc.class operation}}
+  %1 = get_field @testField : !emitc.array<1xf32>
+  %2 = subscript %1[%0] : (!emitc.array<1xf32>, !emitc.size_t) -> !emitc.lvalue<f32>
+  return
+}
+
+// -----
+
+emitc.class @testClass {
+  emitc.func @testMethod() {
+    %0 = "emitc.constant"() <{value = 0 : index}> : () -> !emitc.size_t
+    // expected-error @+1 {{'emitc.get_field' op field '@testField' not found in the class}}
+    %1 = get_field @testField : !emitc.array<1xf32>
+    %2 = subscript %1[%0] : (!emitc.array<1xf32>, !emitc.size_t) -> !emitc.lvalue<f32>
+    return
+  }
+}