Add benchmarks for LocaleDataLookup

on aosp_cf_x86_64_phone-userdebug, the benchmark result is

libandroidfw_benchmarks#BM_LocaleDataLookupIsLocaleRepresentative: PASSED (0ms)
cpu_time_ns: 55.07607273354898
real_time_ns: 55.19976479889459
libandroidfw_benchmarks#BM_LocaleDataLookupLikelyScript: PASSED (0ms)
cpu_time_ns: 87.99205759931041
real_time_ns: 88.19010674954154

With the unordered_set and unordered_map, the result is

libandroidfw_benchmarks#BM_LocaleDataLookupIsLocaleRepresentative: PASSED (0ms)
cpu_time_ns: 113.01179143336402
real_time_ns: 113.3695957412614
libandroidfw_benchmarks#BM_LocaleDataLookupLikelyScript: PASSED (1ms)
cpu_time_ns: 109.63471229710265
real_time_ns: 109.91545630537807

With std::binary_search, the result is

libandroidfw_benchmarks#BM_LocaleDataLookupIsLocaleRepresentative: PASSED (0ms)
cpu_time_ns: 123.82590108826805
real_time_ns: 123.98891085230711

Let's keep the current implementation, and add a TODO about the disk
size.

Bug: 383096413
Test: atest libandroidfw_benchmarks
Change-Id: Iaa5f1ab5ac4dcc6bbdd3c4b66fe129c61d75c1d1

4 files changed, 73 insertions, 1 deletions

diff --git a/libs/androidfw/Android.bp b/libs/androidfw/Android.bp
index a13dd78a23a1..104ba018fb62 100644
--- a/libs/androidfw/Android.bp
+++ b/libs/androidfw/Android.bp
@@ -287,6 +287,7 @@ cc_benchmark {
         "tests/AttributeResolution_bench.cpp",
         "tests/CursorWindow_bench.cpp",
         "tests/Generic_bench.cpp",
+        "tests/LocaleDataLookup_bench.cpp",
         "tests/SparseEntry_bench.cpp",
         "tests/Theme_bench.cpp",
     ],
diff --git a/libs/androidfw/LocaleDataLookup.cpp b/libs/androidfw/LocaleDataLookup.cpp
index 6e751a77f355..ea9e9a2d4280 100644
--- a/libs/androidfw/LocaleDataLookup.cpp
+++ b/libs/androidfw/LocaleDataLookup.cpp
@@ -7518,6 +7518,13 @@ const char* lookupLikelyScript(uint32_t packed_lang_region) {
      }
 }
 
+/*
+ * TODO: Consider turning the below switch statement into binary search
+ *      to save the disk space when the table is larger in the future.
+ *      Disassembled code shows that the jump table emitted by clang can be
+ *      4x larger than the data in disk size, but it depends on the optimization option.
+ *      However, a switch statement will benefit from the future of compiler improvement.
+ */
 bool isLocaleRepresentative(uint32_t language_and_region, const char* script) {
     const uint64_t packed_locale =
             ((static_cast<uint64_t>(language_and_region)) << 32u) |
diff --git a/libs/androidfw/tests/LocaleDataLookup_bench.cpp b/libs/androidfw/tests/LocaleDataLookup_bench.cpp
new file mode 100644
index 000000000000..60ce3b944551
--- /dev/null
+++ b/libs/androidfw/tests/LocaleDataLookup_bench.cpp
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2025 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "benchmark/benchmark.h"
+
+#include "androidfw/LocaleDataLookup.h"
+
+namespace android {
+
+static void BM_LocaleDataLookupIsLocaleRepresentative(benchmark::State& state) {
+  for (auto&& _ : state) {
+    isLocaleRepresentative(packLocale("en", "US"), "Latn");
+    isLocaleRepresentative(packLocale("es", "ES"), "Latn");
+    isLocaleRepresentative(packLocale("zh", "CN"), "Hans");
+    isLocaleRepresentative(packLocale("pt", "BR"), "Latn");
+    isLocaleRepresentative(packLocale("ar", "EG"), "Arab");
+    isLocaleRepresentative(packLocale("hi", "IN"), "Deva");
+    isLocaleRepresentative(packLocale("jp", "JP"), "Jpan");
+  }
+}
+BENCHMARK(BM_LocaleDataLookupIsLocaleRepresentative);
+
+static void BM_LocaleDataLookupLikelyScript(benchmark::State& state) {
+  for (auto&& _ : state) {
+    lookupLikelyScript(packLocale("en", ""));
+    lookupLikelyScript(packLocale("es", ""));
+    lookupLikelyScript(packLocale("zh", ""));
+    lookupLikelyScript(packLocale("pt", ""));
+    lookupLikelyScript(packLocale("ar", ""));
+    lookupLikelyScript(packLocale("hi", ""));
+    lookupLikelyScript(packLocale("jp", ""));
+    lookupLikelyScript(packLocale("en", "US"));
+    lookupLikelyScript(packLocale("es", "ES"));
+    lookupLikelyScript(packLocale("zh", "CN"));
+    lookupLikelyScript(packLocale("pt", "BR"));
+    lookupLikelyScript(packLocale("ar", "EG"));
+    lookupLikelyScript(packLocale("hi", "IN"));
+    lookupLikelyScript(packLocale("jp", "JP"));
+  }
+}
+BENCHMARK(BM_LocaleDataLookupLikelyScript);
+
+
+}  // namespace android
diff --git a/tools/localedata/extract_icu_data.py b/tools/localedata/extract_icu_data.py
index ec531275af1c..899cd7f9ce5e 100755
--- a/tools/localedata/extract_icu_data.py
+++ b/tools/localedata/extract_icu_data.py
@@ -180,7 +180,14 @@ def pack_script_to_uint32(script):
 
 def dump_representative_locales(representative_locales):
     """Dump the set of representative locales."""
-    print()
+    print('''
+/*
+ * TODO: Consider turning the below switch statement into binary search
+ *      to save the disk space when the table is larger in the future.
+ *      Disassembled code shows that the jump table emitted by clang can be
+ *      4x larger than the data in disk size, but it depends on the optimization option.
+ *      However, a switch statement will benefit from the future of compiler improvement.
+ */''')
     print('bool isLocaleRepresentative(uint32_t language_and_region, const char* script) {')
     print('    const uint64_t packed_locale =')
     print('            ((static_cast<uint64_t>(language_and_region)) << 32u) |')