[onnx] Update reader utils

lib/onnx/reader.ml

@@ -189,37 +189,50 @@ end = struct
             (module String)
             (List.map ~f:(fun a -> (Option.value_exn a.name, a)) n.attribute)
         in
-        let get_float name : float =
-          match Hashtbl.find_exn attrs name with
-          | { type' = Some AttributeProto.AttributeType.FLOAT; f = Some f; _ }
-            ->
-            f
-          | _ -> failwith "Attribute wrongly typed"
+        let get_attr ?default name m =
+          match Hashtbl.find attrs name with
+          | Some v -> m v
+          | None -> (
+            match default with
+            | Some v -> v
+            | None -> Fmt.failwith "Required attribute %s missing" name)
         in
-        let get_int name : int =
-          match Hashtbl.find_exn attrs name with
-          | { type' = Some AttributeProto.AttributeType.INT; i = Some i; _ } ->
-            Int64.to_int_exn i
-          | _ -> failwith "Attribute wrongly typed"
+        let get_float ?default name : float =
+          get_attr ?default name (function
+            | { type' = Some AttributeProto.AttributeType.FLOAT; f = Some f; _ }
+              ->
+              f
+            | _ -> failwith "Attribute wrongly typed")
         in
-        let get_ints name : int list =
-          match Hashtbl.find_exn attrs name with
-          | { type' = Some AttributeProto.AttributeType.INTS; ints = l; _ } ->
-            List.map ~f:Int64.to_int_exn l
-          | _ -> failwith "Attribute wrongly typed"
+        let get_int ?default name : int =
+          get_attr ?default name (function
+            | { type' = Some AttributeProto.AttributeType.INT; i = Some i; _ }
+              ->
+              Int64.to_int_exn i
+            | _ -> failwith "Attribute wrongly typed")
         in
-        let get_bool name : bool =
-          match Hashtbl.find_exn attrs name with
-          | { type' = Some AttributeProto.AttributeType.INT; i = Some i; _ } ->
-            not (Int64.equal i 0L)
-          | _ -> failwith "Attribute wrongly typed"
+        let get_ints ?default name : int list =
+          get_attr ?default name (function
+            | { type' = Some AttributeProto.AttributeType.INTS; ints = l; _ } ->
+              List.map ~f:Int64.to_int_exn l
+            | _ -> failwith "Attribute wrongly typed")
         in
-        let get_tensor name : Nir.Gentensor.t =
-          match Hashtbl.find_exn attrs name with
-          | { type' = Some AttributeProto.AttributeType.TENSOR; t = Some t; _ }
-            ->
-            convert_tensor t
-          | _ -> failwith "Attribute wrongly typed"
+        let get_bool ?default name : bool =
+          get_attr ?default name (function
+            | { type' = Some AttributeProto.AttributeType.INT; i = Some i; _ }
+              ->
+              not (Int64.equal i 0L)
+            | _ -> failwith "Attribute wrongly typed")
+        in
+        let get_tensor ?default name : Nir.Gentensor.t =
+          get_attr ?default name (function
+            | {
+                type' = Some AttributeProto.AttributeType.TENSOR;
+                t = Some t;
+                _;
+              } ->
+              convert_tensor t
+            | _ -> failwith "Attribute wrongly typed")
         in
         let n' =
           match n.op_type with
@@ -257,10 +270,10 @@ end = struct
                   inputA = convert inputA;
                   inputB = convert inputB;
                   inputC = Option.map ~f:convert inputC;
-                  alpha = get_float "alpha";
-                  beta = get_float "beta";
-                  transA = get_bool "transA";
-                  transB = get_bool "transB";
+                  alpha = get_float ~default:1.0 "alpha";
+                  beta = get_float ~default:1.0 "beta";
+                  transA = get_bool ~default:false "transA";
+                  transB = get_bool ~default:false "transB";
                 }
             | "LogSoftmax" -> Nir.Node.LogSoftmax
             | "Transpose" ->