[dynamic shapes] simplify int(x / y) pattern

test/export/test_export.py

@@ -701,6 +701,35 @@ def forward(self, x):
     return (add,)""",
         )
 
+    def test_int_shape_specialization(self):
+        class M(torch.nn.Module):
+            def forward(self, x):
+                ori_size = (
+                    int(x.shape[-2] / 1),
+                    int(x.shape[-1] / 1),
+                )
+                x = F.interpolate(x, size=ori_size, mode="bilinear")
+                return x
+
+        input1 = (torch.rand(1, 3, 28, 28),)
+        input2 = (torch.rand(1, 3, 56, 56),)
+        inputs = [input1, input2]
+        model = M()
+        dynamic_shapes = {
+            "x": {2: torch.export.Dim.DYNAMIC, 3: torch.export.Dim.DYNAMIC},
+        }
+        with self.assertRaisesRegex(
+            (
+                torch.fx.experimental.symbolic_shapes.ConstraintViolationError,
+                torch._dynamo.exc.UserError,
+            ),
+            (
+                r"your code specialized it to be a constant \(28\)(.*\n)*.*"
+                r"your code specialized it to be a constant \(28\)(.*\n)*.*"
+            ),
+        ):
+            export(model, input1, dynamic_shapes=dynamic_shapes, strict=False)
+
     def test_external_call_non_strict_real_tensor(self):
         class ExternalMethod:
             def add(self, x):

torch/fx/experimental/symbolic_shapes.py

@@ -78,11 +78,13 @@
     CleanDiv,
     FloorDiv,
     FloorToInt,
+    IntTrueDiv,
     IsNonOverlappingAndDenseIndicator,
     Max,
     Min,
     Mod,
     PythonMod,
+    TruncToInt,
 )
 from torch.utils._sympy.numbers import int_oo
 from torch.utils._sympy.printers import CppPrinter, PythonPrinter
@@ -5990,6 +5992,16 @@ def simplify(self, expr: _SympyT, size_oblivious: bool = False) -> _SympyT:
             if min_max_replacements:
                 expr = expr.xreplace(min_max_replacements)
 
+        if expr.has(TruncToInt):
+            trunc_replacements = {}
+            for atom in expr.atoms(TruncToInt):
+                if isinstance(atom.args[0], IntTrueDiv):
+                    base, divisor = atom.args[0].args
+                    if base % divisor == 0:
+                        trunc_replacements[atom] = base // divisor
+            if trunc_replacements:
+                expr = expr.xreplace(trunc_replacements)
+
         # TODO it would seem that this pass is not necessary given the
         # below replacement of // with /, but for nested FloorDivs
         # the non-recursive replacement doesn't work, and