code cleanup for extending the gemm operator

src/include/migraphx/operators.hpp

@@ -840,12 +840,13 @@ struct dot
             MIGRAPHX_THROW("DOT: second matrix, dimensions before matrix dims must be 1");
         }
 
-        std::size_t n_dims = a.lens().size();
-        if(a.lens()[n_dims - 1] != b.lens()[n_dims - 2])
+        std::size_t dim_0 = a.lens().size() - 2;
+        std::size_t dim_1 = a.lens().size() - 1;
+        if(a.lens()[dim_1] != b.lens()[dim_0])
             MIGRAPHX_THROW("Inner dimensions do not match: {" + to_string_range(a.lens()) +
                            "} x {" + to_string_range(b.lens()) + "}");
         auto out_lens        = a.lens();
-        out_lens[n_dims - 1] = b.lens()[n_dims - 1];
+        out_lens[dim_1] = b.lens()[dim_1];
         return {t, out_lens};
     }
 };

src/onnx/onnx.cpp

@@ -469,7 +469,6 @@ struct onnx_parser
         {
             transb = parse_value(attributes.at("transB")).at<bool>();
         }
-
         std::vector<int64_t> perm = {1, 0};
         auto l1 = (transa) ? prog.add_instruction(op::transpose{perm}, args[0]) : args[0];
         auto l2 = (transb) ? prog.add_instruction(op::transpose{perm}, args[1]) : args[1];
@@ -490,10 +489,7 @@ struct onnx_parser
                 return add_broadcastable_binary_op(l3, l4, op::add{});
             }
         }
-
-        auto dot_res = prog.add_instruction(op::dot{alpha, beta}, l1, l2);
-
-        return dot_res;
+        return prog.add_instruction(op::dot{alpha, beta}, l1, l2);
     }
 
     instruction_ref