Cortex_m backend: Add script for building test runner

Change-Id: I566e68320531cf7c233764de2a6a7be29e284ec4
Signed-off-by: Adrian Lundell <[email protected]>

Author: AdrianLundell

backends/cortex_m/test/build_test_runner.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+# Copyright 2025 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.
+
+# TODO: More separation from the regular arm executor runner and testing.
+
+set -eu
+
+# Always rebuild executorch in case the cortex-m kernels has been updated.
+script_dir=$(realpath "$(dirname "${BASH_SOURCE[0]}")")
+et_root_dir=$(realpath "${script_dir}/../../..")
+build_executorch="${et_root_dir}/backends/arm/scripts/build_executorch.sh"
+${build_executorch}
+
+# Build executor runner with all portable ops selected and semi hosting
+build_dir="${et_root_dir}/arm_test"
+build_executor_runner="${et_root_dir}/backends/arm/scripts/build_executor_runner.sh"
+build_root_test_dir="${et_root_dir}/arm_test/arm_semihosting_executor_runner_corstone-300"
+
+${build_executor_runner} --pte=semihosting --target=ethos-u55-128 --output="${build_root_test_dir}"