[Torch Dialect] emit aten::warn (llvm#3003)

* torch-mlir may not handle `aten.warn`. But it could be handled by
custom users' backend which involves torch-mlir.

include/torch-mlir/Dialect/Torch/IR/GeneratedTorchOps.td

@@ -13148,6 +13148,29 @@ def Torch_AtenJoinOp : Torch_Op<"aten.join", [
   }];
 }
 
+def Torch_AtenWarnOp : Torch_Op<"aten.warn", [
+    AllowsTypeRefinement,
+    HasValueSemantics,
+    ReadOnly
+  ]> {
+  let summary = "Generated op for `aten::warn : (str, int) -> ()`";
+  let arguments = (ins
+    Torch_StringType:$message,
+    Torch_IntType:$stacklevel
+  );
+  let results = (outs
+  );
+  let hasCustomAssemblyFormat = 1;
+  let extraClassDefinition = [{
+    ParseResult AtenWarnOp::parse(OpAsmParser &parser, OperationState &result) {
+      return parseDefaultTorchOp(parser, result, 2, 0);
+    }
+    void AtenWarnOp::print(OpAsmPrinter &printer) {
+      printDefaultTorchOp(printer, *this, 2, 0);
+    }
+  }];
+}
+
 def Torch_AtenFloatScalarOp : Torch_Op<"aten.Float.Scalar", [
     AllowsTypeRefinement,
     HasValueSemantics,

projects/pt1/python/torch_mlir/jit_ir_importer/build_tools/torch_ods_gen.py

@@ -753,6 +753,7 @@ def emit_with_mutating_variants(key, **kwargs):
     emit("aten::str : (t) -> (str)")
     emit("aten::format : (...) -> (str)")
     emit("aten::join : (str, str[]) -> (str)")
+    emit("aten::warn : (str, int) -> ()")
 
     # Type conversion ops.
     emit("aten::Float.Scalar : (Scalar) -> (float)", has_folder=True)