[Bug Fix] Fix SymInt issue in subgraph decomposition (#506)

* fix

* Add blank line for improved readability

Author: fangfangssj

graph_net/torch/fx_graph_parse_util.py

@@ -174,18 +174,14 @@ def get_diff_input_names():
             if name not in placeholder_names
         ]
 
-    if len(inputs) == len(traced_sample_inputs) + 1:
-        diff_input_names = get_diff_input_names()
-        assert len(diff_input_names) == 1, f"{diff_input_names=}"
-        pos, name = diff_input_names[0]
-        for i, node in enumerate(traced_module.graph.nodes):
-            if i < pos:
-                assert node.op == "placeholder"
-            elif i == pos:
-                with traced_module.graph.inserting_before(node):
-                    traced_module.graph.placeholder(name)
-            else:
-                break
+    diff_input_names = get_diff_input_names()
+    if len(diff_input_names) > 0:
+        first_node = next(iter(traced_module.graph.nodes))
+
+        with traced_module.graph.inserting_before(first_node):
+            for _, name in diff_input_names:
+                traced_module.graph.placeholder(name)
+
         traced_module.recompile()
 
     def get_zip_filter_names():