Remove outdated NCHW to NHWC pass and rename the current one to ReplaceConvWithChannelLastConvPass (#13420)

Summary:
Pull Request resolved: #13420

The existing `ReplaceConvWithChannelLastConvPass` is a PT1 pass from years past, and currently does not do anything. The correct version of it is `ForceChannelLastForConvPass`, so we rename that one to `ReplaceConvWithChannelLastConvPass`.
This should be a non-functional change.

Reviewed By: ethansfng, hsharma35

Differential Revision: D80185231

Author: mcremon-meta

backends/cadence/aot/replace_ops.py

@@ -772,186 +772,6 @@ def call_operator(self, op, args, kwargs, meta):
         return super().call_operator(target, new_args, kwargs, meta)
 
 
-# TODO(matthiascremon): this is a fuse op, not a replace op
-class ReplaceConvWithChannelLastConv:
-    """
-    Convolution op in pytorch expects NCHW layout for input, weight, and output
-    tensors. However, if the input and output to the convolution op are originally
-    in NWHC layout, and are then permuted to conform to NCHW layout, we can fuse
-    the two permute ops with the convolution op, and call the NHWC layout
-    convolution op.
-    """
-
-    def __init__(self):
-        self.counter = 0
-        self.graph_module = None
-
-    def __call__(self, graph_module: torch.fx.GraphModule):
-        self.replace_conv_with_nhwc_conv(graph_module)
-
-    def conv_layout_is_nhwc(self, node: torch.fx.Node) -> bool:
-        """
-        Return true if the convolution input and output are connected to permute
-        ops, and the input/output to/from the permute ops is NHWC layout tensor.
-        """
-        # There must only be a single user of the output node (which must be a
-        # permute/tranpsose op). The input of the convolution must be connected
-        # to a permute op, and that permute op should have a single user.
-        conv_inp = node.args[0]
-        assert isinstance(conv_inp, torch.fx.Node)
-        if len(node.users) != 1 or len(conv_inp.users) != 1:
-            return False
-
-        # Get the input and output (permute/transpose) nodes of the convolution
-        conv_user = list(node.users.keys())[0]
-        assert isinstance(conv_user, torch.fx.Node)
-        pt_nodes: Set[torch.fx.Node] = {conv_inp, conv_user}
-
-        # Any node in pt_nodes must not be a placeholder.
-        if contains_placeholder_or_param(pt_nodes):
-            return False
-
-        # Determine if the convolution is 1d or 2d. The output tensor must be
-        # 3- or 4-dimensional
-        out_shape = get_shape(self.graph_module, node)
-        assert out_shape is not None
-        out_dims = len(out_shape)
-        assert out_dims in {3, 4}, "Only supports conv1d and conv2d"
-        conv1d = out_dims == 3
-
-        # Get the possible targets for the nodes in pt_nodes. Since conv1d has
-        # 3-dimensional input and output tensors, the nodes in pt_nodes could
-        # be either permute or transpose op. For conv2d, the nodes in pt_nodes
-        # must be permute ops.
-        p_target = exir_ops.edge.aten.permute_copy.default
-        t_target = exir_ops.edge.aten.transpose_copy.int
-        pt_targets = [p_target] + ([t_target] if conv1d else [])
-
-        # If any node in pt_nodes is not permute op (or tranpose op for conv1d),
-        # bail.
-        if any(x.target not in pt_targets for x in pt_nodes):
-            return False
-
-        # Now we need to determine the dimension permutations:
-        # If the input had NHWC layout, which was then permuted/transposed
-        # by a permute/transpose op to NCHW layout, the permutation must be
-        # [0, 3, 2, 1] (or [0, 2, 1] for conv1d).
-        # If the output had NCHW layout, and was then permuted to NHWC layout,
-        # the permutation must be [0, 2, 3, 1] (or [0, 2, 1] for conv1d).
-        nhwc_permute_order = {
-            node.args[0]: [0, 2, 1] if conv1d else [0, 3, 1, 2],
-            list(node.users.keys())[0]: [0, 2, 1] if conv1d else [0, 2, 3, 1],
-        }
-        for x in pt_nodes:
-            order = (
-                x.args[1]
-                if x.target == p_target
-                else get_transposed_dims(x, list(range(out_dims)))
-            )
-            if order != nhwc_permute_order[x]:
-                return False
-
-        return True
-
-    def replace_conv_with_nhwc_conv(self, graph_module: torch.fx.GraphModule):
-        self.graph_module = graph_module
-        graph = graph_module.graph
-        for node in graph.nodes:
-            # We are only interested in convolution nodes that have NHWC layout
-            if node.target not in {
-                exir_ops.edge.cadence.quantized_conv.default,
-                exir_ops.edge.cadence.convolution.default,
-                exir_ops.edge.cadence.quantized_transposed_conv.default,
-                exir_ops.edge.cadence.transposed_convolution.default,
-            } or not self.conv_layout_is_nhwc(node):
-                continue
-
-            # Get the args of convolution op
-            args = list(node.args)
-            # The input is connected to a permute/transpose op that converts the
-            # NHWC layout to NCHW layout. The input of the permute op will become
-            # this convolution op's input.
-            in_tp = args[0]
-            args[0] = in_tp.args[0]
-            # The weight is in NHWC layout. Permute it to NHWC layout.
-            weight_tensor = get_tensor_from_attr(graph_module, args[1])
-            assert isinstance(weight_tensor, torch.Tensor)
-            # We cannot directly permute a per-channel quantized tensor. We will
-            # dequantize it, permute the fp32 tensor, and then requantize the
-            # permuted tensor.
-            if (
-                is_quantized_tensor(weight_tensor)
-                and weight_tensor.qscheme() == torch.per_channel_affine
-            ):
-                # We have already asserted during quantizing conv op that the
-                # quantization axis is 0.
-                dequant_weight = weight_tensor.dequantize()
-                dequant_weight = (
-                    dequant_weight.permute([0, 2, 1])
-                    if dequant_weight.dim() == 3
-                    else dequant_weight.permute([0, 2, 3, 1])
-                )
-                weight_tensor = torch.quantize_per_channel(
-                    dequant_weight.contiguous(),
-                    weight_tensor.q_per_channel_scales(),
-                    weight_tensor.q_per_channel_zero_points(),
-                    0,
-                    weight_tensor.dtype,
-                )
-            else:
-                weight_tensor = (
-                    weight_tensor.permute([0, 2, 1])
-                    if weight_tensor.dim() == 3
-                    else weight_tensor.permute([0, 2, 3, 1])
-                )
-            # Make the weight tensor contiguous, since we have permuted it.
-            weight_tensor = weight_tensor.contiguous()
-            # Add the permuted weight into the graph, and update the weight in
-            # args.
-            with graph.inserting_before(node):
-                weight_name = f"_weight_nhwc_{self.counter}"
-                graph_module.register_buffer(weight_name, weight_tensor)
-                weight = graph.get_attr(weight_name)
-            args[1] = weight
-
-            # The 'channel_last' arg is True. It is the last arg.
-            args[-1] = True
-            # Now update the convolution node args to mark it as NHWC convolution
-            node.args = tuple(args)
-
-            # Replace all the uses of the permute op connected to the output op
-            # with this convolution.
-            out_tp = list(node.users.keys())[0]
-            out_tp.replace_all_uses_with(node)
-            node.meta = out_tp.meta
-
-            # Erase the permute ops connected to the input and output of the
-            # convolution op.
-            graph.erase_node(in_tp)
-            graph.erase_node(out_tp)
-            self.counter += 1
-
-        graph_module.recompile()
-
-
-# This pass needs to be reworked to be compatible with PT2. It is an optimization
-# pass anyway, so move it to opt level 2.
-# TODO: T213724613 update and improve this pass.
-# @register_cadence_pass(CadencePassAttribute(opt_level=2))
-class ReplaceConvWithChannelLastConvPass(ExportPass):
-    """
-    Replace the ATen convolution op with custom conv op with NCHW or NHWC layout
-    input tensors, depending on the presence of permute/transpose ops connected
-    to the input tensor.
-    """
-
-    def call(self, graph_module: torch.fx.GraphModule) -> PassResult:
-        result = ReplaceAtenConvolutionWithCadenceConvolutionPass()(graph_module)
-        assert result is not None
-        ReplaceConvWithChannelLastConv()(result.graph_module)
-        return result
-
-
 @register_cadence_pass(CadencePassAttribute(opt_level=2))
 class ReplaceTrivialConvWithLinear(ExportPass):
     """
@@ -1127,7 +947,7 @@ def transpose_dims(
 
 
 @register_cadence_pass(CadencePassAttribute(opt_level=3))
-class ForceChannelLastForConvPass(ExportPassWithTransposeHelper):
+class ReplaceConvWithChannelLastConvPass(ExportPassWithTransposeHelper):
     def change_nchw_to_nhwc(self, proxy: ProxyValue, meta: NodeMetadata) -> ProxyValue:
         shape = proxy.to_tensor().shape
         if len(shape) == 3:
@@ -2429,9 +2249,8 @@ class CadenceReplaceOpsInGraph:
         ReplaceRepeatWithCatPass,
         ReplacePadWithCatPass,
         ReplaceConstantPadNdWithSlicePass,
-        ReplaceConvWithChannelLastConvPass,
         ReplaceAtenConvolutionWithCadenceConvolutionPass,
-        ForceChannelLastForConvPass,
+        ReplaceConvWithChannelLastConvPass,
         ReplaceTrivialConvWithLinear,
         ReplaceConvWithIm2RowAndLinear,
         ReplaceTransposedConvWithLinearPass,

backends/cadence/aot/tests/test_replace_ops_passes.py

@@ -17,14 +17,14 @@
 )
 from executorch.backends.cadence.aot.pass_utils import count_node, op_counts_match
 from executorch.backends.cadence.aot.replace_ops import (
-    ForceChannelLastForConvPass,
     MakeSliceAndCatDimOutermostPass,
     ReplaceAdaptiveAvgPoolWithAtenAvgPoolPass,
     ReplaceAddMMWithLinearPass,
     ReplaceAtenApproxGeluWithApproxGeluPass,
     ReplaceAtenConvolutionWithCadenceConvolutionPass,
     ReplaceConstantPadNdWithSlicePass,
     ReplaceConvolutionOptionalArgsWithConcreteArgsPass,
+    ReplaceConvWithChannelLastConvPass,
     ReplaceConvWithIm2RowAndLinear,
     ReplaceEmptyTensorsWithFullPass,
     ReplaceFunctionallyEquivalentOpTargets,
@@ -1454,7 +1454,7 @@ def test_replace_linear_like_conv(self) -> None:
         )
 
 
-class TestForceChannelLastForConvPass(unittest.TestCase):
+class TestReplaceConvWithChannelLastConvPass(unittest.TestCase):
     def create_conv1d_graphmodule(
         self, channels_last: Optional[bool] = None
     ) -> torch.fx.GraphModule:
@@ -1489,7 +1489,7 @@ def test_conv1d_default_channel_last(self) -> None:
         self.assertEqual(count_node(gm, exir_ops.edge.aten.transpose_copy.int), 0)
 
         # Apply replacement pass.
-        p = ForceChannelLastForConvPass()
+        p = ReplaceConvWithChannelLastConvPass()
         gm_after_replacement = p.call(gm).graph_module
         # Check that no replacement was made.
         self.assertEqual(
@@ -1514,7 +1514,7 @@ def test_conv1d_no_transpose_if_already_channel_last(self) -> None:
         self.assertEqual(count_node(gm, exir_ops.edge.cadence.convolution.default), 1)
 
         # Apply replacement pass.
-        p = ForceChannelLastForConvPass()
+        p = ReplaceConvWithChannelLastConvPass()
         gm_after_replacement = p.call(gm).graph_module
         # Check that no replacement was made.
         self.assertEqual(
@@ -1566,7 +1566,7 @@ def test_convolution_default_channel_last(self) -> None:
         self.assertEqual(count_node(gm, exir_ops.edge.aten.permute_copy.default), 0)
 
         # Apply replacement pass.
-        p = ForceChannelLastForConvPass()
+        p = ReplaceConvWithChannelLastConvPass()
         gm_after_replacement = p.call(gm).graph_module
         # Check that no replacement was made.
         self.assertEqual(
@@ -1591,7 +1591,7 @@ def test_no_transpose_if_already_channel_last(self) -> None:
         self.assertEqual(count_node(gm, exir_ops.edge.cadence.convolution.default), 1)
 
         # Apply replacement pass.
-        p = ForceChannelLastForConvPass()
+        p = ReplaceConvWithChannelLastConvPass()
         gm_after_replacement = p.call(gm).graph_module
         # Check that no replacement was made.
         self.assertEqual(
@@ -1671,7 +1671,7 @@ def test_quantized_convolution_default_channel_last(self) -> None:
         self.assertEqual(count_node(gm, exir_ops.edge.aten.permute_copy.default), 0)
 
         # Apply replacement pass.
-        p = ForceChannelLastForConvPass()
+        p = ReplaceConvWithChannelLastConvPass()
         gm_after_replacement = p.call(gm).graph_module
         # Check that no replacement was made.
         self.assertEqual(
@@ -1702,7 +1702,7 @@ def test_no_transpose_if_already_quantized_conv_channel_last(self) -> None:
         )
 
         # Apply replacement pass.
-        p = ForceChannelLastForConvPass()
+        p = ReplaceConvWithChannelLastConvPass()
         gm_after_replacement = p.call(gm).graph_module
         # Check that no replacement was made.
         self.assertEqual(