[fx] Update symbolic_trace nn_module_stack (#114422)

Summary:
Fixed nn_module_stack dynamo produced by symbolic trace to align with the nn_module_stack metadata produced by dynamo. The key should be the module path, with the value being a unique name, and the type. Something like: `{'L__self___one_module': ("L['self'].one_module", <class 'torch.fx.graph_module.GraphModule.__new__.<locals>.GraphModuleImpl'>)}`

This was causing some tests to fail when using export + the old quantization flow (prepare_fx calls symbolic_trace).

Test Plan: D51534471 `buck2 run @//mode/dev-nosan //executorch/backends/xnnpack/test:test_xnnpack_quantized -- -r "test_xnnpack_leaky_relu"`

Differential Revision: D51539118

Pull Request resolved: https://github.com/pytorch/pytorch/pull/114422
Approved by: https://github.com/JacobSzwejbka, https://github.com/jerryzh168

test/test_fx.py

@@ -1752,8 +1752,8 @@ class TestFX(JitTestCase):
         gm = torch.fx.symbolic_trace(m)
 
         mod_stack = {}
-        expected_stack = [('sub_mod', type(m.sub_mod)),
-                          ('sub_mod.conv_mod', type(m.sub_mod.conv_mod))]
+        expected_stack = [('sub_mod', ('sub_mod', type(m.sub_mod))),
+                          ('sub_mod.conv_mod', ('sub_mod.conv_mod', type(m.sub_mod.conv_mod)))]
         for node in gm.graph.nodes:
             mod_stack = node.meta.get('nn_module_stack', {})
             if mod_stack:

torch/fx/_symbolic_trace.py

@@ -478,7 +478,7 @@ class Tracer(TracerBase):
         with ScopeContextManager(self.scope, Scope(module_qualified_name, type(m))) as _scope:
             # module_stack is an ordered dict so writing then deleting the
             # entry is equivalent to push/pop on a list
-            self.module_stack[_scope.module_path] = _scope.module_type
+            self.module_stack[_scope.module_path] = (module_qualified_name, _scope.module_type)
             if not self.is_leaf_module(m, module_qualified_name):
                 ret_val = forward(*args, **kwargs)
             else:

torch/fx/proxy.py

@@ -107,7 +107,7 @@ class TracerBase:
     scope : Scope
 
     # Records the module call stack
-    module_stack: OrderedDict[str, str]
+    module_stack: OrderedDict[str, Tuple[str, Any]]
 
     # Mapping of node name to module scope
     node_name_to_scope: Dict[str, Tuple[str, type]]