Support SymInt placeholder in wrapper fxir (#167757)

Summary:
add support for symint placeholders

added two test cases with dynamic reshape
- dynamic info coming from tmd on placeholders
- dynamic info coming from placeholders (symints)

Test Plan:
test_reshape_dynamic_ph
test_reshape_dynamic_tmd

Differential Revision: D86984100

Pull Request resolved: https://github.com/pytorch/pytorch/pull/167757
Approved by: https://github.com/blaine-rister

test/inductor/test_fxir_backend.py

@@ -831,7 +831,9 @@ class AOTFxirTestCase(InductorTestCase):
             gm = torch._inductor.aot_compile(
                 ep.module(), inp, options={"fx_wrapper": True, **test_config}
             )
-            self.assertTrue(same(model(*inp), gm(*inp)))
+            # Flatten args for fx_wrapper gm
+            flat_args, _ = pytree.tree_flatten(inp)
+            self.assertTrue(same(model(*inp), gm(*flat_args)))
 
             for node in gm.graph.nodes:
                 if (
@@ -1182,6 +1184,38 @@ def forward(self, arg0_1, arg1_1, arg2_1):
             compiled_out = compiled(*args)
             self.assertEqual(compiled_out.shape, shape)
 
+    def test_reshape_dynamic_ph(self):
+        """
+        Test dynamic scalars using SymInts placeholder
+        """
+
+        class TestModule(torch.nn.Module):
+            def forward(self, x, shape):
+                return torch.reshape(x, shape) + 2
+
+        ds = {
+            "x": (torch.export.Dim.AUTO, torch.export.Dim.AUTO),
+            "shape": [torch.export.Dim.AUTO, torch.export.Dim.AUTO],
+        }
+        args = (torch.randn((12, 14), device=self.device), [6, 28])
+        self.check(TestModule(), args, ds)
+
+    def test_reshape_dynamic_tmd(self):
+        """
+        Test dynamic reshape using shape dependent information
+        """
+
+        class TestModule(torch.nn.Module):
+            def forward(self, x):
+                new_shape = [x.shape[0] // 2, x.shape[1] * 2]
+                return torch.reshape(x, new_shape) + 2
+
+        ds = {
+            "x": (torch.export.Dim.AUTO, torch.export.Dim.AUTO),
+        }
+        args = (torch.randn((12, 14), device=self.device),)
+        self.check(TestModule(), args, ds)
+
 
 class TestReplaceFloorDiv(InductorTestCase):
     """

torch/_inductor/compile_fx.py

@@ -2537,16 +2537,19 @@ def _extract_inputs_from_exported_gm(
     fake_inputs = [
         node.meta.get("val") for node in gm.graph.nodes if node.op == "placeholder"
     ]
-    # Replace non-tensor (constant) inputs with Nones, since these are not being
-    # used anyways by the graph
-    fake_inputs = [
-        inp if isinstance(inp, torch.Tensor) else None for inp in fake_inputs
-    ]
+
+    if not config.fx_wrapper:
+        # Replace non-tensor inputs with Nones
+        # constant scalars embedded in the graph
+        # symbolic scalars (symint) are not supported in non-fx_wrapper mode
+        fake_inputs = [
+            inp if isinstance(inp, torch.Tensor) else None for inp in fake_inputs
+        ]
 
     if any(v is not None for v in fake_inputs):
         # Validate devices before switching to fake tensors.
         for idx, fi, i in zip(count(), fake_inputs, example_inputs_):
-            if fi is not None:
+            if fi is not None and isinstance(fi, torch.Tensor):
                 assert isinstance(i, torch.Tensor)
                 if fi.device != i.device:
                     raise ValueError(