Arm backend: Add LSTM unit test to arm backend (#7787)

Add LSTM unit test to arm backend
Adding check that number of delegates=1

Author: SaoirseARM

backends/arm/test/models/test_lstm_arm.py

@@ -0,0 +1,101 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Copyright 2025 Arm Limited and/or its affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+
+import unittest
+
+import torch
+
+from executorch.backends.arm.test import common, conftest
+from executorch.backends.arm.test.tester.arm_tester import ArmTester
+
+from torch.nn.quantizable.modules import rnn
+
+
+class TestLSTM(unittest.TestCase):
+    """Tests quantizable LSTM module."""
+
+    """
+    Currently only the quantizable LSTM module has been verified with the arm backend.
+    There may be plans to update this to use torch.nn.LSTM.
+    TODO: MLETORCH-622
+    """
+    lstm = rnn.LSTM(10, 20, 2)
+    lstm = lstm.eval()
+
+    input_tensor = torch.randn(5, 3, 10)
+    h0 = torch.randn(2, 3, 20)
+    c0 = torch.randn(2, 3, 20)
+
+    model_inputs = (input_tensor, (h0, c0))
+
+    def test_lstm_tosa_MI(self):
+        (
+            ArmTester(
+                self.lstm,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_tosa_compile_spec("TOSA-0.80+MI"),
+            )
+            .export()
+            .to_edge_transform_and_lower()
+            .check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
+            .to_executorch()
+            .run_method_and_compare_outputs(inputs=self.model_inputs)
+        )
+
+    def test_lstm_tosa_BI(self):
+        (
+            ArmTester(
+                self.lstm,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_tosa_compile_spec("TOSA-0.80+BI"),
+            )
+            .quantize()
+            .export()
+            .to_edge_transform_and_lower()
+            .check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
+            .to_executorch()
+            .run_method_and_compare_outputs(atol=3e-1, qtol=1, inputs=self.model_inputs)
+        )
+
+    def test_lstm_u55_BI(self):
+        tester = (
+            ArmTester(
+                self.lstm,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_u55_compile_spec(),
+            )
+            .quantize()
+            .export()
+            .to_edge_transform_and_lower()
+            .check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
+            .to_executorch()
+            .serialize()
+        )
+        if conftest.is_option_enabled("corstone_fvp"):
+            tester.run_method_and_compare_outputs(
+                atol=3e-1, qtol=1, inputs=self.model_inputs
+            )
+
+    def test_lstm_u85_BI(self):
+        tester = (
+            ArmTester(
+                self.lstm,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_u85_compile_spec(),
+            )
+            .quantize()
+            .export()
+            .to_edge_transform_and_lower()
+            .check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
+            .to_executorch()
+            .serialize()
+        )
+        if conftest.is_option_enabled("corstone_fvp"):
+            tester.run_method_and_compare_outputs(
+                atol=3e-1, qtol=1, inputs=self.model_inputs
+            )