Arm backend: Reject Squeeze no-op partition (pytorch#19662)

Reject delegates of squeeze op that are no-op in
the partitioner


cc @digantdesai @freddan80 @per @zingo @oscarandersson8218 @mansnils
@Sebastian-Larsson @robell @rascani

Signed-off-by: Christoffer J.L <christoffer.johanssonlundqvist@arm.com>

Author: Christoffer-JL

backends/arm/test/ops/test_squeeze.py

@@ -1,4 +1,4 @@
-# Copyright 2024-2025 Arm Limited and/or its affiliates.
+# Copyright 2024-2026 Arm Limited and/or its affiliates.
 #
 # This source code is licensed under the BSD-style license found in the
 # LICENSE file in the root directory of this source tree.
@@ -16,6 +16,7 @@
 from executorch.backends.arm.test.tester.test_pipeline import (
     EthosU55PipelineINT,
     EthosU85PipelineINT,
+    OpNotSupportedPipeline,
     TosaPipelineFP,
     TosaPipelineINT,
     VgfPipeline,
@@ -60,6 +61,12 @@ def forward(self, x: torch.Tensor):
         return x.squeeze()
 
 
+unsupported_cases = {
+    "squeeze_dim_no_effect": lambda: (torch.randn(3, 4, 5), 1),
+    "squeeze_no_effect": lambda: (torch.randn(3, 4, 5),),
+}
+
+
 ##############
 ## Squeeze ###
 ##############
@@ -137,6 +144,16 @@ def test_squeeze_dim_vgf_quant(test_data: Tuple):
     pipeline.run()
 
 
+def test_squeeze_no_target_not_delegated() -> None:
+    pipeline = OpNotSupportedPipeline[input_t1](
+        Squeeze(),
+        unsupported_cases["squeeze_no_effect"](),
+        {"executorch_exir_dialects_edge__ops_aten_squeeze_copy_dims": 1},
+        n_expected_delegates=0,
+    )
+    pipeline.run()
+
+
 #################
 ## SqueezeDim ###
 #################
@@ -214,6 +231,16 @@ def test_squeeze_dim_vgf_quant_2(test_data: Tuple):
     pipeline.run()
 
 
+def test_squeeze_dim_no_target_not_delegated() -> None:
+    pipeline = OpNotSupportedPipeline[Tuple[torch.Tensor, int]](
+        SqueezeDim(),
+        unsupported_cases["squeeze_dim_no_effect"](),
+        {"executorch_exir_dialects_edge__ops_aten_squeeze_copy_dims": 1},
+        n_expected_delegates=0,
+    )
+    pipeline.run()
+
+
 ##################
 ## SqueezeDims ###
 ##################

backends/arm/tosa/partitioner.py

@@ -104,6 +104,15 @@ def _is_noop_expand(node: torch.fx.node.Node) -> bool:
     return all(m == 1 for m in multiples) and not changes_rank
 
 
+def _is_noop_squeeze(node: torch.fx.Node) -> bool:
+    if node.target != exir_ops.edge.aten.squeeze_copy.dims:
+        return False
+    else:
+        input_tensor = get_first_fake_tensor(ensure_type(torch.fx.Node, node.args[0]))
+        output_tensor = get_first_fake_tensor(node)
+        return input_tensor.shape == output_tensor.shape
+
+
 def _is_view_copy(node: torch.fx.node.Node) -> bool:
     return node.target == exir_ops.edge.aten.view_copy.default
 
@@ -388,6 +397,7 @@ def is_node_supported(self, submodules, node: torch.fx.Node) -> bool:
                 or _is_noop_expand(node)
                 or _is_noop_detach_copy(node)
                 or _is_noop_to_dim_order_copy(node)
+                or _is_noop_squeeze(node)
                 or _is_view_copy(node)
                 or _is_noop_as_strided_copy(node)
                 or node.target in Q_OPS