summaryrefslogtreecommitdiff
path: root/absl/strings/internal/fastmem_test.cc
diff options
context:
space:
mode:
Diffstat (limited to 'absl/strings/internal/fastmem_test.cc')
-rw-r--r--absl/strings/internal/fastmem_test.cc453
1 files changed, 0 insertions, 453 deletions
diff --git a/absl/strings/internal/fastmem_test.cc b/absl/strings/internal/fastmem_test.cc
deleted file mode 100644
index 7c670f96..00000000
--- a/absl/strings/internal/fastmem_test.cc
+++ /dev/null
@@ -1,453 +0,0 @@
-// Copyright 2017 The Abseil 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.
-
-#include "absl/strings/internal/fastmem.h"
-
-#include <memory>
-#include <random>
-#include <string>
-
-#include "base/init_google.h"
-#include "base/logging.h"
-#include "testing/base/public/benchmark.h"
-#include "gtest/gtest.h"
-
-namespace {
-
-using RandomEngine = std::minstd_rand0;
-
-void VerifyResults(const int r1, const int r2, const std::string& a,
- const std::string& b) {
- CHECK_EQ(a.size(), b.size());
- if (r1 == 0) {
- EXPECT_EQ(r2, 0) << a << " " << b;
- } else if (r1 > 0) {
- EXPECT_GT(r2, 0) << a << " " << b;
- } else {
- EXPECT_LT(r2, 0) << a << " " << b;
- }
- if ((r1 == 0) == (r2 == 0)) {
- EXPECT_EQ(r1 == 0,
- absl::strings_internal::memeq(a.data(), b.data(), a.size()))
- << r1 << " " << a << " " << b;
- }
-}
-
-// Check correctness against glibc's memcmp implementation
-void CheckSingle(const std::string& a, const std::string& b) {
- CHECK_EQ(a.size(), b.size());
- const int r1 = memcmp(a.data(), b.data(), a.size());
- const int r2 =
- absl::strings_internal::fastmemcmp_inlined(a.data(), b.data(), a.size());
- VerifyResults(r1, r2, a, b);
-}
-
-void GenerateString(size_t len, std::string* s) {
- s->clear();
- for (int i = 0; i < len; i++) {
- *s += ('a' + (i % 26));
- }
-}
-
-void CheckCompare(const std::string& a, const std::string& b) {
- CheckSingle(a, b);
- for (int common = 0; common <= 32; common++) {
- std::string extra;
- GenerateString(common, &extra);
- CheckSingle(extra + a, extra + b);
- CheckSingle(a + extra, b + extra);
- for (char c1 = 'a'; c1 <= 'c'; c1++) {
- for (char c2 = 'a'; c2 <= 'c'; c2++) {
- CheckSingle(extra + c1 + a, extra + c2 + b);
- }
- }
- }
-}
-
-TEST(FastCompare, Misc) {
- CheckCompare("", "");
-
- CheckCompare("a", "a");
- CheckCompare("ab", "ab");
- CheckCompare("abc", "abc");
- CheckCompare("abcd", "abcd");
- CheckCompare("abcde", "abcde");
-
- CheckCompare("a", "x");
- CheckCompare("ab", "xb");
- CheckCompare("abc", "xbc");
- CheckCompare("abcd", "xbcd");
- CheckCompare("abcde", "xbcde");
-
- CheckCompare("x", "a");
- CheckCompare("xb", "ab");
- CheckCompare("xbc", "abc");
- CheckCompare("xbcd", "abcd");
- CheckCompare("xbcde", "abcde");
-
- CheckCompare("a", "x");
- CheckCompare("ab", "ax");
- CheckCompare("abc", "abx");
- CheckCompare("abcd", "abcx");
- CheckCompare("abcde", "abcdx");
-
- CheckCompare("x", "a");
- CheckCompare("ax", "ab");
- CheckCompare("abx", "abc");
- CheckCompare("abcx", "abcd");
- CheckCompare("abcdx", "abcde");
-
- for (int len = 0; len < 1000; len++) {
- std::string p(len, 'z');
- CheckCompare(p + "x", p + "a");
- CheckCompare(p + "ax", p + "ab");
- CheckCompare(p + "abx", p + "abc");
- CheckCompare(p + "abcx", p + "abcd");
- CheckCompare(p + "abcdx", p + "abcde");
- }
-}
-
-TEST(FastCompare, TrailingByte) {
- for (int i = 0; i < 256; i++) {
- for (int j = 0; j < 256; j++) {
- std::string a(1, i);
- std::string b(1, j);
- CheckSingle(a, b);
- }
- }
-}
-
-// Check correctness of memcpy_inlined.
-void CheckSingleMemcpyInlined(const std::string& a) {
- std::unique_ptr<char[]> destination(new char[a.size() + 2]);
- destination[0] = 'x';
- destination[a.size() + 1] = 'x';
- absl::strings_internal::memcpy_inlined(destination.get() + 1, a.data(),
- a.size());
- CHECK_EQ('x', destination[0]);
- CHECK_EQ('x', destination[a.size() + 1]);
- CHECK_EQ(0, memcmp(a.data(), destination.get() + 1, a.size()));
-}
-
-TEST(MemCpyInlined, Misc) {
- CheckSingleMemcpyInlined("");
- CheckSingleMemcpyInlined("0");
- CheckSingleMemcpyInlined("012");
- CheckSingleMemcpyInlined("0123");
- CheckSingleMemcpyInlined("01234");
- CheckSingleMemcpyInlined("012345");
- CheckSingleMemcpyInlined("0123456");
- CheckSingleMemcpyInlined("01234567");
- CheckSingleMemcpyInlined("012345678");
- CheckSingleMemcpyInlined("0123456789");
- CheckSingleMemcpyInlined("0123456789a");
- CheckSingleMemcpyInlined("0123456789ab");
- CheckSingleMemcpyInlined("0123456789abc");
- CheckSingleMemcpyInlined("0123456789abcd");
- CheckSingleMemcpyInlined("0123456789abcde");
- CheckSingleMemcpyInlined("0123456789abcdef");
- CheckSingleMemcpyInlined("0123456789abcdefg");
-}
-
-template <typename Function>
-inline void CopyLoop(benchmark::State& state, int size, Function func) {
- char* src = new char[size];
- char* dst = new char[size];
- memset(src, 'x', size);
- memset(dst, 'y', size);
- for (auto _ : state) {
- func(dst, src, size);
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * size);
- CHECK_EQ(dst[0], 'x');
- delete[] src;
- delete[] dst;
-}
-
-void BM_memcpy(benchmark::State& state) {
- CopyLoop(state, state.range(0), memcpy);
-}
-BENCHMARK(BM_memcpy)->DenseRange(1, 18)->Range(32, 8 << 20);
-
-void BM_memcpy_inlined(benchmark::State& state) {
- CopyLoop(state, state.range(0), absl::strings_internal::memcpy_inlined);
-}
-BENCHMARK(BM_memcpy_inlined)->DenseRange(1, 18)->Range(32, 8 << 20);
-
-// unaligned memcpy
-void BM_unaligned_memcpy(benchmark::State& state) {
- const int n = state.range(0);
- const int kMaxOffset = 32;
- char* src = new char[n + kMaxOffset];
- char* dst = new char[n + kMaxOffset];
- memset(src, 'x', n + kMaxOffset);
- int r = 0, i = 0;
- for (auto _ : state) {
- memcpy(dst + (i % kMaxOffset), src + ((i + 5) % kMaxOffset), n);
- r += dst[0];
- ++i;
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * n);
- delete[] src;
- delete[] dst;
- benchmark::DoNotOptimize(r);
-}
-BENCHMARK(BM_unaligned_memcpy)->DenseRange(1, 18)->Range(32, 8 << 20);
-
-// memmove worst case: heavy overlap, but not always by the same amount.
-// Also, the source and destination will often be unaligned.
-void BM_memmove_worst_case(benchmark::State& state) {
- const int n = state.range(0);
- const int32_t kDeterministicSeed = 301;
- const int kMaxOffset = 32;
- char* src = new char[n + kMaxOffset];
- memset(src, 'x', n + kMaxOffset);
- size_t offsets[64];
- RandomEngine rng(kDeterministicSeed);
- std::uniform_int_distribution<size_t> random_to_max_offset(0, kMaxOffset);
- for (size_t& offset : offsets) {
- offset = random_to_max_offset(rng);
- }
- int r = 0, i = 0;
- for (auto _ : state) {
- memmove(src + offsets[i], src + offsets[i + 1], n);
- r += src[0];
- i = (i + 2) % arraysize(offsets);
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * n);
- delete[] src;
- benchmark::DoNotOptimize(r);
-}
-BENCHMARK(BM_memmove_worst_case)->DenseRange(1, 18)->Range(32, 8 << 20);
-
-// memmove cache-friendly: aligned and overlapping with 4k
-// between the source and destination addresses.
-void BM_memmove_cache_friendly(benchmark::State& state) {
- const int n = state.range(0);
- char* src = new char[n + 4096];
- memset(src, 'x', n);
- int r = 0;
- while (state.KeepRunningBatch(2)) { // count each memmove as an iteration
- memmove(src + 4096, src, n);
- memmove(src, src + 4096, n);
- r += src[0];
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * n);
- delete[] src;
- benchmark::DoNotOptimize(r);
-}
-BENCHMARK(BM_memmove_cache_friendly)
- ->Arg(5 * 1024)
- ->Arg(10 * 1024)
- ->Range(16 << 10, 8 << 20);
-
-// memmove best(?) case: aligned and non-overlapping.
-void BM_memmove_aligned_non_overlapping(benchmark::State& state) {
- CopyLoop(state, state.range(0), memmove);
-}
-BENCHMARK(BM_memmove_aligned_non_overlapping)
- ->DenseRange(1, 18)
- ->Range(32, 8 << 20);
-
-// memset speed
-void BM_memset(benchmark::State& state) {
- const int n = state.range(0);
- char* dst = new char[n];
- int r = 0;
- for (auto _ : state) {
- memset(dst, 'x', n);
- r += dst[0];
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * n);
- delete[] dst;
- benchmark::DoNotOptimize(r);
-}
-BENCHMARK(BM_memset)->Range(8, 4096 << 10);
-
-// Bandwidth (vectorization?) test: the ideal generated code will be limited
-// by memory bandwidth. Even so-so generated code will max out memory bandwidth
-// on some machines.
-void BM_membandwidth(benchmark::State& state) {
- const int n = state.range(0);
- CHECK_EQ(n % 32, 0); // We will read 32 bytes per iter.
- char* dst = new char[n];
- int r = 0;
- for (auto _ : state) {
- const uint32_t* p = reinterpret_cast<uint32_t*>(dst);
- const uint32_t* limit = reinterpret_cast<uint32_t*>(dst + n);
- uint32_t x = 0;
- while (p < limit) {
- x += p[0];
- x += p[1];
- x += p[2];
- x += p[3];
- x += p[4];
- x += p[5];
- x += p[6];
- x += p[7];
- p += 8;
- }
- r += x;
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * n);
- delete[] dst;
- benchmark::DoNotOptimize(r);
-}
-BENCHMARK(BM_membandwidth)->Range(32, 16384 << 10);
-
-// Helper for benchmarks. Repeatedly compares two strings that are
-// either equal or different only in one character. If test_equal_strings
-// is false then position_to_modify determines where the difference will be.
-template <typename Function>
-ABSL_ATTRIBUTE_ALWAYS_INLINE inline void StringCompareLoop(
- benchmark::State& state, bool test_equal_strings,
- std::string::size_type position_to_modify, int size, Function func) {
- const int kIterMult = 4; // Iteration multiplier for better timing resolution
- CHECK_GT(size, 0);
- const bool position_to_modify_is_valid =
- position_to_modify != std::string::npos && position_to_modify < size;
- CHECK_NE(position_to_modify_is_valid, test_equal_strings);
- if (!position_to_modify_is_valid) {
- position_to_modify = 0;
- }
- std::string sa(size, 'a');
- std::string sb = sa;
- char last = sa[size - 1];
- int num = 0;
- for (auto _ : state) {
- for (int i = 0; i < kIterMult; ++i) {
- sb[position_to_modify] = test_equal_strings ? last : last ^ 1;
- num += func(sa, sb);
- }
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * size);
- benchmark::DoNotOptimize(num);
-}
-
-// Helper for benchmarks. Repeatedly compares two memory regions that are
-// either equal or different only in their final character.
-template <typename Function>
-ABSL_ATTRIBUTE_ALWAYS_INLINE inline void CompareLoop(benchmark::State& state,
- bool test_equal_strings,
- int size, Function func) {
- const int kIterMult = 4; // Iteration multiplier for better timing resolution
- CHECK_GT(size, 0);
- char* data = static_cast<char*>(malloc(size * 2));
- memset(data, 'a', size * 2);
- char* a = data;
- char* b = data + size;
- char last = a[size - 1];
- int num = 0;
- for (auto _ : state) {
- for (int i = 0; i < kIterMult; ++i) {
- b[size - 1] = test_equal_strings ? last : last ^ 1;
- num += func(a, b, size);
- }
- }
- state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * size);
- benchmark::DoNotOptimize(num);
- free(data);
-}
-
-void BM_memcmp(benchmark::State& state) {
- CompareLoop(state, false, state.range(0), memcmp);
-}
-BENCHMARK(BM_memcmp)->DenseRange(1, 9)->Range(32, 8 << 20);
-
-void BM_fastmemcmp_inlined(benchmark::State& state) {
- CompareLoop(state, false, state.range(0),
- absl::strings_internal::fastmemcmp_inlined);
-}
-BENCHMARK(BM_fastmemcmp_inlined)->DenseRange(1, 9)->Range(32, 8 << 20);
-
-void BM_memeq(benchmark::State& state) {
- CompareLoop(state, false, state.range(0), absl::strings_internal::memeq);
-}
-BENCHMARK(BM_memeq)->DenseRange(1, 9)->Range(32, 8 << 20);
-
-void BM_memeq_equal(benchmark::State& state) {
- CompareLoop(state, true, state.range(0), absl::strings_internal::memeq);
-}
-BENCHMARK(BM_memeq_equal)->DenseRange(1, 9)->Range(32, 8 << 20);
-
-bool StringLess(const std::string& x, const std::string& y) { return x < y; }
-bool StringEqual(const std::string& x, const std::string& y) { return x == y; }
-bool StdEqual(const std::string& x, const std::string& y) {
- return x.size() == y.size() &&
- std::equal(x.data(), x.data() + x.size(), y.data());
-}
-
-// Benchmark for x < y, where x and y are strings that differ in only their
-// final char. That should be more-or-less the worst case for <.
-void BM_string_less(benchmark::State& state) {
- StringCompareLoop(state, false, state.range(0) - 1, state.range(0),
- StringLess);
-}
-BENCHMARK(BM_string_less)->DenseRange(1, 9)->Range(32, 1 << 20);
-
-// Benchmark for x < y, where x and y are strings that differ in only their
-// first char. That should be more-or-less the best case for <.
-void BM_string_less_easy(benchmark::State& state) {
- StringCompareLoop(state, false, 0, state.range(0), StringLess);
-}
-BENCHMARK(BM_string_less_easy)->DenseRange(1, 9)->Range(32, 1 << 20);
-
-void BM_string_equal(benchmark::State& state) {
- StringCompareLoop(state, false, state.range(0) - 1, state.range(0),
- StringEqual);
-}
-BENCHMARK(BM_string_equal)->DenseRange(1, 9)->Range(32, 1 << 20);
-
-void BM_string_equal_equal(benchmark::State& state) {
- StringCompareLoop(state, true, std::string::npos, state.range(0), StringEqual);
-}
-BENCHMARK(BM_string_equal_equal)->DenseRange(1, 9)->Range(32, 1 << 20);
-
-void BM_std_equal(benchmark::State& state) {
- StringCompareLoop(state, false, state.range(0) - 1, state.range(0), StdEqual);
-}
-BENCHMARK(BM_std_equal)->DenseRange(1, 9)->Range(32, 1 << 20);
-
-void BM_std_equal_equal(benchmark::State& state) {
- StringCompareLoop(state, true, std::string::npos, state.range(0), StdEqual);
-}
-BENCHMARK(BM_std_equal_equal)->DenseRange(1, 9)->Range(32, 1 << 20);
-
-void BM_string_equal_unequal_lengths(benchmark::State& state) {
- const int size = state.range(0);
- std::string a(size, 'a');
- std::string b(size + 1, 'a');
- int count = 0;
- for (auto _ : state) {
- b[size - 1] = 'a';
- count += (a == b);
- }
- benchmark::DoNotOptimize(count);
-}
-BENCHMARK(BM_string_equal_unequal_lengths)->Arg(1)->Arg(1 << 20);
-
-void BM_stdstring_equal_unequal_lengths(benchmark::State& state) {
- const int size = state.range(0);
- std::string a(size, 'a');
- std::string b(size + 1, 'a');
- int count = 0;
- for (auto _ : state) {
- b[size - 1] = 'a';
- count += (a == b);
- }
- benchmark::DoNotOptimize(count);
-}
-BENCHMARK(BM_stdstring_equal_unequal_lengths)->Arg(1)->Arg(1 << 20);
-
-} // namespace
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-08 02:35:28 +0000