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

1 files changed, 7 insertions, 0 deletions

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) |