[Bug Fix] Fix padding when running in NHWC

Author: mcr229

backends/xnnpack/operators/op_static_constant_pad.py

@@ -7,6 +7,7 @@
 from typing import cast, Dict, List
 
 import torch
+
 from executorch.backends.xnnpack.operators.node_visitor import (
     get_tensor_value,
     NodeVisitor,
@@ -17,7 +18,11 @@
     XNNStaticConstantPad,
     XNode,
 )
-from executorch.backends.xnnpack.utils.utils import check_or_raise, get_input_node
+from executorch.backends.xnnpack.utils.utils import (
+    check_or_raise,
+    get_input_node,
+    PERM_NCHW_TO_NHWC,
+)
 
 
 @register_node_visitor
@@ -113,8 +118,15 @@ def define_node(
         # b)
         # tuple[0] = prepadding dim[-1]
         # tuple[1] = postpadding dim[-1]
+        is_channels_last = node.meta.get("XNN_NHWC_NODE", False)
         pre_paddings = all_paddings[-2::-2]  # even index elements in reverse order
         post_paddings = all_paddings[::-2]  # odd index elements in reverse order
+        if is_channels_last:
+            check_or_raise(len(pre_paddings) == 4, "Expecting prepaddings to be 4D")
+            check_or_raise(len(post_paddings) == 4, "Expecting postpaddings to be 4D")
+
+            pre_paddings = [pre_paddings[i] for i in PERM_NCHW_TO_NHWC]
+            post_paddings = [post_paddings[i] for i in PERM_NCHW_TO_NHWC]
 
         # the padding value, which defaults to 0.0
         padding_value = cast(float, node.args[2]) if len(node.args) > 2 else 0.0

backends/xnnpack/test/ops/test_static_constant_pad.py

@@ -14,6 +14,30 @@ class TestStaticConstantPad(unittest.TestCase):
     def setUp(self):
         torch._dynamo.reset()
 
+    class NHWCStaticConstantPad(torch.nn.Module):
+        def __init__(self):
+            super().__init__()
+            self.conv1 = torch.nn.Conv2d(in_channels=2, out_channels=2, kernel_size=1)
+            self.conv2 = torch.nn.Conv2d(in_channels=13, out_channels=13, kernel_size=1)
+
+        def forward(self, x):
+            a = self.conv1(x)
+            pad_6 = (1, 2, 3, 4, 5, 6)
+            a = torch.nn.functional.pad(
+                input=a,
+                pad=pad_6,
+                mode="constant",
+                value=3.1,
+            )
+            # tensorshape = [1, 13, 10, 7]
+            a = self.conv2(a)
+
+            return a
+
+        def sample_inputs(self):
+            # NCHW
+            return (torch.randn(1, 2, 3, 4),)
+
     class StaticConstantPadFunctional(torch.nn.Module):
         def __init__(self):
             super().__init__()
@@ -205,3 +229,24 @@ def test_qs8_static_constant_pad_2d(self):
             .serialize()
             .run_method_and_compare_outputs()
         )
+
+    def test_fp32_static_constant_pad_nhwc(self):
+        conv = self.NHWCStaticConstantPad()
+        inputs = conv.sample_inputs()
+        (
+            Tester(conv, inputs)
+            .export()
+            .check_count({"torch.ops.aten.pad.default": 1})
+            .dump_artifact()
+            .to_edge_transform_and_lower()
+            .check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
+            .check_not(
+                [
+                    "executorch_exir_dialects_edge__ops_aten_constant_pad_nd_default",
+                    "executorch_exir_dialects_edge__ops_aten_convolution_default",
+                ]
+            )
+            .to_executorch()
+            .serialize()
+            .run_method_and_compare_outputs()
+        )