benchmarks/wchar_benchmark.cpp

/*
 * Copyright (C) 2025 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
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#include <wchar.h>

#include <benchmark/benchmark.h>
#include <util.h>

// NOTE: While we support wchar functions being passed unaligned pointers for
// compatibility purposes, we intentionally do not benchmark that case, because
// it's expected to be extremely rare. If devs want fast wchar, they can align
// their buffers correctly.

static void BM_wchar_wcslen(benchmark::State& state) {
  const size_t nbytes = state.range(0) * sizeof(wchar_t);
  const size_t alignment = state.range(1);

  std::vector<char> buf;
  char* buf_aligned = GetAlignedPtrFilled(&buf, alignment, nbytes, 'x');

  memset(buf_aligned + nbytes - sizeof(wchar_t), 0, sizeof(wchar_t));
  while (state.KeepRunning()) {
    benchmark::DoNotOptimize(wcslen(reinterpret_cast<const wchar_t*>(buf_aligned)));
  }

  state.SetBytesProcessed(uint64_t(state.iterations()) * uint64_t(nbytes));
}
BIONIC_BENCHMARK_WITH_ARG(BM_wchar_wcslen, "AT_ALIGNED_ONEBUF");

static void BM_wchar_wmemchr(benchmark::State& state) {
  const size_t nchars = state.range(0);
  const size_t alignment = state.range(1);

  const size_t nbytes = nchars * sizeof(wchar_t);
  std::vector<char> buf;
  char* buf_aligned = GetAlignedPtrFilled(&buf, alignment, nbytes + 1, 'x');

  wchar_t needle = L'a';
  memcpy(buf_aligned + nbytes - sizeof(wchar_t), &needle, sizeof(needle));
  while (state.KeepRunning()) {
    benchmark::DoNotOptimize(
        wmemchr(reinterpret_cast<const wchar_t*>(buf_aligned), needle, nchars));
  }

  state.SetBytesProcessed(uint64_t(state.iterations()) * uint64_t(nbytes));
}
BIONIC_BENCHMARK_WITH_ARG(BM_wchar_wmemchr, "AT_ALIGNED_ONEBUF");

static void WMemSetBenchmark(benchmark::State& state, wchar_t wc) {
  const size_t nchars = state.range(0);
  const size_t alignment = state.range(1);

  const size_t nbytes = nchars * sizeof(wchar_t);
  std::vector<char> buf;
  char* buf_aligned = GetAlignedPtr(&buf, alignment, nbytes + 1);

  while (state.KeepRunning()) {
    wmemset(reinterpret_cast<wchar_t*>(buf_aligned), wc, nchars);
  }

  state.SetBytesProcessed(uint64_t(state.iterations()) * uint64_t(nbytes));
}

static void BM_wchar_wmemset_0(benchmark::State& state) {
  WMemSetBenchmark(state, 0);
}
BIONIC_BENCHMARK_WITH_ARG(BM_wchar_wmemset_0, "AT_ALIGNED_ONEBUF");

static void BM_wchar_wmemset_666(benchmark::State& state) {
  WMemSetBenchmark(state, 666);
}
BIONIC_BENCHMARK_WITH_ARG(BM_wchar_wmemset_666, "AT_ALIGNED_ONEBUF");