add script for verifying dead code elimination

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

hack/verify-deadcode-elimination.sh

@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+
+# Copyright 2025 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This script verifies if the golang linker is eliminating dead code in
+# various components we care about, such as kube-apiserver, kubelet and others
+# Usage: `hack/verify-deadcode-elimination.sh`.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+KUBE_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
+source "${KUBE_ROOT}/hack/lib/init.sh"
+
+kube::golang::setup_env
+
+# Ensure that we find the binaries we build before anything else.
+export GOBIN="${KUBE_OUTPUT_BIN}"
+PATH="${GOBIN}:${PATH}"
+
+# Install whydeadcode
+go install github.com/aarzilli/whydeadcode@latest
+
+# Prefer full path for running zeitgeist
+WHYDEADCODE_BIN="$(which whydeadcode)"
+
+pushd "${KUBE_ROOT}"
+
+# Define an array of binaries to check
+BINARIES=("kube-apiserver" "kubelet" "kube-controller-manager" "kube-scheduler" "kube-proxy")
+FAILED=false
+FAILED_BINARIES=()
+
+for binary in "${BINARIES[@]}"; do
+  echo "Processing ${binary} ..."
+  output=$(KUBE_VERBOSE=4 GOLDFLAGS=-dumpdep make "${binary}" 2>&1 | grep "\->" | ${WHYDEADCODE_BIN} 2>&1)
+  if [[ -n "$output" ]]; then
+    echo "golang linker is not eliminating dead code in ${binary}, please check the trace output below:"
+    echo "(NOTE: that there may be false positives, but the first trace should be a real issue)"
+    echo "$output"
+    FAILED=true
+    FAILED_BINARIES+=("${binary}")
+  fi
+  
+  # Find the binary and print its size
+  echo "Finding ${binary} binary and checking its size:"
+  binary_paths=$(find _output -type f -name "${binary}" | sort)
+  if [[ -n "${binary_paths}" ]]; then
+    # shellcheck disable=SC2086
+    ls -altrh ${binary_paths}
+  else
+    echo "Binary ${binary} not found in _output directory"
+  fi
+  echo ""
+done
+
+popd > /dev/null || true
+
+if [[ "$FAILED" == "true" ]]; then
+  echo "Dead code elimination check failed for the following binaries:"
+  for failed_binary in "${FAILED_BINARIES[@]}"; do
+    echo "  - ${failed_binary}"
+  done
+  exit 1
+fi