empty_permute decomposition (#2698)

Author: apbose

py/torch_tensorrt/dynamo/lowering/_decompositions.py

@@ -162,6 +162,18 @@ def var_decomposition(
     return variance
 
 
+@register_torch_trt_decomposition(
+    torch.ops.aten.empty_permuted.default, registry=TORCH_TRT_DECOMPOSITIONS
+)
+def empty_permuted_decomposition(*args, **kwargs) -> torch.Tensor:
+    empty_size = args[0]
+    empty_permute = args[1]
+    perm = [0] * len(empty_size)
+    for permute_index, permute_element in enumerate(empty_permute):
+        perm[permute_element] = permute_index
+    return torch.empty([empty_size[l] for l in empty_permute], **kwargs).permute(perm)
+
+
 def get_decompositions(
     enable_experimental_decompositions: bool = False,
 ) -> Dict[OpOverload, Callable[[Any], Any]]:

tests/py/dynamo/lowering/test_decompositions.py

@@ -420,6 +420,71 @@ def forward(self, x):
             f"MaxPool3d TRT outputs don't match with the original model.",
         )
 
+    def test_lowering_empty_like_module(self):
+        class emptyLike(torch.nn.Module):
+            def __init__(self, *args, **kwargs) -> None:
+                super().__init__(*args, **kwargs)
+
+            def forward(self, x):
+                c = torch.ops.aten.add(x, x)
+                y = torch.ops.aten.empty_like.default(c)
+                d = y + c
+                return d
+
+        # Operations expected to be removed in the traced graph after decompositions
+        expected_ops = {torch.ops.aten.add.Tensor}
+        unexpected_ops = {
+            torch.ops.aten.empty_like.default,
+            torch.ops.aten.empty_permuted.default,
+        }
+
+        inputs = [torch.zeros(3, 2).cuda()]
+
+        fx_graph = torch.fx.symbolic_trace(emptyLike())
+        unexpected_ops_seen, expected_ops_unseen = lower_graph_testing(
+            fx_graph,
+            inputs,
+            expected_ops=expected_ops,
+            unexpected_ops=unexpected_ops,
+            min_block_size=1,
+        )
+
+        self.assertEquals(
+            len(unexpected_ops_seen),
+            0,
+            f"The following unexpected ops were encountered: {unexpected_ops_seen}",
+        )
+
+        self.assertEquals(
+            len(expected_ops_unseen),
+            0,
+            f"The following expected ops were not encountered: {expected_ops_unseen}",
+        )
+
+        torch._dynamo.reset()
+
+        # Validate that the results between Torch and Torch-TRT are similar
+        optimized_model = torch_tensorrt.compile(
+            fx_graph,
+            "torch_compile",
+            inputs,
+            min_block_size=1,
+            truncate_long_and_double=True,
+            pass_through_build_failures=True,
+        )
+        optimized_model_results = optimized_model(*inputs).detach().cpu()
+        torch_model_results = fx_graph(*inputs).detach().cpu()
+
+        max_diff = float(
+            torch.max(torch.abs(optimized_model_results - torch_model_results))
+        )
+        self.assertAlmostEqual(
+            max_diff,
+            0,
+            DECIMALS_OF_AGREEMENT,
+            f"Select_scatter TRT outputs don't match with the original model.",
+        )
+
 
 if __name__ == "__main__":
     run_tests()