[export] Skip noop runtime assertion pass. (pytorch#109395)

Summary:
If there's no inline constraints added, just return the original graph.
We want to do this because sometimes this pass mess up the node names,
before we actually fix this, we could make the behavior a bit less buggy
by skipping noop passes.

Test Plan:

Reviewers:

Subscribers:

Tasks:

Tags:

Fixes #ISSUE_NUMBER

Pull Request resolved: pytorch#109395
Approved by: https://github.com/angelayi

torch/_export/passes/add_runtime_assertions_for_constraints_pass.py

@@ -59,6 +59,7 @@ def __init__(
         super().__init__()
         self.range_constraints: Dict[sympy.Symbol, RangeConstraint] = range_constraints
         self.equality_constraints: List[Tuple[InputDim, InputDim]] = equality_constraints
+        self.counter = 0
 
     def _assert_range_constraint(self, proxy, lower, upper, assert_msg):
         if lower > -math.inf:
@@ -72,6 +73,7 @@ def _insert_assert_async(self, operator, lower, upper, assert_msg):
         Inserts assert_async call_function nodes in the graph. This function is
         called **during** the interpreter-based pass.
         """
+        self.counter += 1
         cmp = super().call_operator(operator, (lower, upper), {}, self._create_dummy_node_metadata())
         cmp_tensor = super().call_operator(torch.ops.aten.scalar_tensor.default, (cmp,), {}, self._create_dummy_node_metadata())
         super().call_operator(
@@ -139,6 +141,11 @@ def call(self, graph_module):
         # Add runtime asserts for inline constraints
         val = super().call(graph_module)
 
+        # Sometimes this pass would return a wrong graph where we have mismatched
+        # node names in signature. Before we fix it, let's just skip it.
+        if self.counter == 0 and type(self) is _AddRuntimeAssertionsForInlineConstraintsPass:
+            return PassResult(graph_module, False)
+
         # Populate the stack trace with dummy vals to respect IR
         for node in val.graph_module.graph.nodes:
             if not node.meta.get("stack_trace", None):