Changes imported from Abseil "staging" branch:
- 43853019b439efb32c79d5d50e24508588e1bbe0 Undo the not applying qualifications to absl types in enc... by Derek Mauro <dmauro@google.com> - 06d62a10621c9864279ee57097069cfe3cb7b42a fix capitalization by Abseil Team <absl-team@google.com> - 22adbfee340bb452ba38b68975ade6f072859c4a Fix indices in str_split.h comments. by Derek Mauro <dmauro@google.com> - ae5143a559ad8633a78cd76620e30a781006d088 Fix the inconsistent licenses directives in the BUILD fil... by Derek Mauro <dmauro@google.com> - 0a76a3653b2ecfdad433d3e2f5b651c4ecdcf74b Remove strip.cc, fastmem.h, and fastmem_test.cc from the ... by Derek Mauro <dmauro@google.com> - 77908cfce5927aabca1f8d62481106f22cfc1936 Internal change. by Derek Mauro <dmauro@google.com> - d3277b4171f37e22ab346becb5e295c36c7a0219 Be consistent in (not) applying qualifications for enclos... by Abseil Team <absl-team@google.com> - 9ec7f8164e7d6a5f64288a7360a346628393cc50 Add std:: qualification to isnan and isinf in duration_te... by Derek Mauro <dmauro@google.com> - 9f7c87d7764ddba05286fabca1f4f15285f3250a Fix typos in string_view comments. by Abseil Team <absl-team@google.com> - 281860804f8053143d969b99876e3dbc6deb1236 Fix typo in container.h docs. by Abseil Team <absl-team@google.com> - 0b0a9388c7a9d7f72349d44b5b46132f45bde56c Add bazel-* symlinks to gitignore. by Michael Pratt <mpratt@google.com> GitOrigin-RevId: 43853019b439efb32c79d5d50e24508588e1bbe0 Change-Id: I9e74a5430816a34ecf1acb86486ed3b0bd12a1d6
This commit is contained in:
Abseil Team
Derek Mauro
parent
7a64d73e1e
commit
cdf20caa49
15 changed files with 66 additions and 998 deletions
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@ -1,215 +0,0 @@
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Fast memory copying and comparison routines.
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// strings::fastmemcmp_inlined() replaces memcmp()
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// strings::memcpy_inlined() replaces memcpy()
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// strings::memeq(a, b, n) replaces memcmp(a, b, n) == 0
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//
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// strings::*_inlined() routines are inline versions of the
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// routines exported by this module. Sometimes using the inlined
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// versions is faster. Measure before using the inlined versions.
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//
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#ifndef ABSL_STRINGS_INTERNAL_FASTMEM_H_
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#define ABSL_STRINGS_INTERNAL_FASTMEM_H_
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#ifdef __SSE4_1__
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#include <immintrin.h>
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#endif
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#include <cstddef>
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#include <cstdint>
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#include <cstdio>
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#include <cstring>
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#include "absl/base/internal/unaligned_access.h"
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#include "absl/base/macros.h"
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#include "absl/base/port.h"
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namespace absl {
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namespace strings_internal {
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// Return true if the n bytes at a equal the n bytes at b.
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// The regions are allowed to overlap.
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//
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// The performance is similar to the performance of memcmp(), but faster for
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// moderately-sized inputs, or inputs that share a common prefix and differ
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// somewhere in their last 8 bytes. Further optimizations can be added later
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// if it makes sense to do so. Alternatively, if the compiler & runtime improve
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// to eliminate the need for this, we can remove it.
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inline bool memeq(const char* a, const char* b, size_t n) {
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size_t n_rounded_down = n & ~static_cast<size_t>(7);
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if (ABSL_PREDICT_FALSE(n_rounded_down == 0)) { // n <= 7
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return memcmp(a, b, n) == 0;
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}
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// n >= 8
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{
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uint64_t u =
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ABSL_INTERNAL_UNALIGNED_LOAD64(a) ^ ABSL_INTERNAL_UNALIGNED_LOAD64(b);
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uint64_t v = ABSL_INTERNAL_UNALIGNED_LOAD64(a + n - 8) ^
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ABSL_INTERNAL_UNALIGNED_LOAD64(b + n - 8);
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if ((u | v) != 0) { // The first or last 8 bytes differ.
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return false;
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}
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}
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// The next line forces n to be a multiple of 8.
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n = n_rounded_down;
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if (n >= 80) {
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// In 2013 or later, this should be fast on long strings.
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return memcmp(a, b, n) == 0;
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}
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// Now force n to be a multiple of 16. Arguably, a "switch" would be smart
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// here, but there's a difficult-to-evaluate code size vs. speed issue. The
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// current approach often re-compares some bytes (worst case is if n initially
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// was 16, 32, 48, or 64), but is fairly short.
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size_t e = n & 8;
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a += e;
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b += e;
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n -= e;
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// n is now in {0, 16, 32, ...}. Process 0 or more 16-byte chunks.
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while (n > 0) {
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#ifdef __SSE4_1__
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__m128i u =
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_mm_xor_si128(_mm_loadu_si128(reinterpret_cast<const __m128i*>(a)),
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_mm_loadu_si128(reinterpret_cast<const __m128i*>(b)));
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if (!_mm_test_all_zeros(u, u)) {
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return false;
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}
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#else
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uint64_t x =
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ABSL_INTERNAL_UNALIGNED_LOAD64(a) ^ ABSL_INTERNAL_UNALIGNED_LOAD64(b);
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uint64_t y = ABSL_INTERNAL_UNALIGNED_LOAD64(a + 8) ^
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ABSL_INTERNAL_UNALIGNED_LOAD64(b + 8);
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if ((x | y) != 0) {
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return false;
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}
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#endif
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a += 16;
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b += 16;
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n -= 16;
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}
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return true;
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}
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inline int fastmemcmp_inlined(const void* va, const void* vb, size_t n) {
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const unsigned char* pa = static_cast<const unsigned char*>(va);
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const unsigned char* pb = static_cast<const unsigned char*>(vb);
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switch (n) {
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default:
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return memcmp(va, vb, n);
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case 7:
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if (*pa != *pb) return *pa < *pb ? -1 : +1;
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++pa;
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++pb;
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ABSL_FALLTHROUGH_INTENDED;
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case 6:
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if (*pa != *pb) return *pa < *pb ? -1 : +1;
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++pa;
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++pb;
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ABSL_FALLTHROUGH_INTENDED;
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case 5:
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if (*pa != *pb) return *pa < *pb ? -1 : +1;
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++pa;
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++pb;
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ABSL_FALLTHROUGH_INTENDED;
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case 4:
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if (*pa != *pb) return *pa < *pb ? -1 : +1;
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++pa;
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++pb;
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ABSL_FALLTHROUGH_INTENDED;
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case 3:
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if (*pa != *pb) return *pa < *pb ? -1 : +1;
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++pa;
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++pb;
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ABSL_FALLTHROUGH_INTENDED;
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case 2:
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if (*pa != *pb) return *pa < *pb ? -1 : +1;
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++pa;
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++pb;
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ABSL_FALLTHROUGH_INTENDED;
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case 1:
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if (*pa != *pb) return *pa < *pb ? -1 : +1;
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ABSL_FALLTHROUGH_INTENDED;
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case 0:
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break;
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}
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return 0;
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}
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// The standard memcpy operation is slow for variable small sizes.
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// This implementation inlines the optimal realization for sizes 1 to 16.
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// To avoid code bloat don't use it in case of not performance-critical spots,
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// nor when you don't expect very frequent values of size <= 16.
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inline void memcpy_inlined(char* dst, const char* src, size_t size) {
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// Compiler inlines code with minimal amount of data movement when third
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// parameter of memcpy is a constant.
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switch (size) {
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case 1:
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memcpy(dst, src, 1);
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break;
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case 2:
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memcpy(dst, src, 2);
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break;
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case 3:
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memcpy(dst, src, 3);
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break;
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case 4:
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memcpy(dst, src, 4);
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break;
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case 5:
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memcpy(dst, src, 5);
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break;
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case 6:
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memcpy(dst, src, 6);
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break;
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case 7:
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memcpy(dst, src, 7);
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break;
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case 8:
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memcpy(dst, src, 8);
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break;
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case 9:
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memcpy(dst, src, 9);
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break;
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case 10:
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memcpy(dst, src, 10);
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break;
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case 11:
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memcpy(dst, src, 11);
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break;
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case 12:
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memcpy(dst, src, 12);
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break;
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case 13:
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memcpy(dst, src, 13);
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break;
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case 14:
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memcpy(dst, src, 14);
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break;
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case 15:
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memcpy(dst, src, 15);
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break;
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case 16:
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memcpy(dst, src, 16);
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break;
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default:
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memcpy(dst, src, size);
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break;
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}
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}
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} // namespace strings_internal
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} // namespace absl
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#endif // ABSL_STRINGS_INTERNAL_FASTMEM_H_
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@ -1,453 +0,0 @@
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "absl/strings/internal/fastmem.h"
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#include <memory>
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#include <random>
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#include <string>
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#include "base/init_google.h"
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#include "base/logging.h"
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#include "testing/base/public/benchmark.h"
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#include "gtest/gtest.h"
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namespace {
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using RandomEngine = std::minstd_rand0;
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void VerifyResults(const int r1, const int r2, const std::string& a,
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const std::string& b) {
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CHECK_EQ(a.size(), b.size());
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if (r1 == 0) {
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EXPECT_EQ(r2, 0) << a << " " << b;
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} else if (r1 > 0) {
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EXPECT_GT(r2, 0) << a << " " << b;
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} else {
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EXPECT_LT(r2, 0) << a << " " << b;
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}
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if ((r1 == 0) == (r2 == 0)) {
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EXPECT_EQ(r1 == 0,
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absl::strings_internal::memeq(a.data(), b.data(), a.size()))
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<< r1 << " " << a << " " << b;
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}
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}
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// Check correctness against glibc's memcmp implementation
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void CheckSingle(const std::string& a, const std::string& b) {
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CHECK_EQ(a.size(), b.size());
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const int r1 = memcmp(a.data(), b.data(), a.size());
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const int r2 =
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absl::strings_internal::fastmemcmp_inlined(a.data(), b.data(), a.size());
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VerifyResults(r1, r2, a, b);
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}
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void GenerateString(size_t len, std::string* s) {
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s->clear();
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for (int i = 0; i < len; i++) {
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*s += ('a' + (i % 26));
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}
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}
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void CheckCompare(const std::string& a, const std::string& b) {
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CheckSingle(a, b);
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for (int common = 0; common <= 32; common++) {
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std::string extra;
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GenerateString(common, &extra);
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CheckSingle(extra + a, extra + b);
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CheckSingle(a + extra, b + extra);
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for (char c1 = 'a'; c1 <= 'c'; c1++) {
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for (char c2 = 'a'; c2 <= 'c'; c2++) {
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CheckSingle(extra + c1 + a, extra + c2 + b);
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}
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}
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}
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}
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TEST(FastCompare, Misc) {
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CheckCompare("", "");
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CheckCompare("a", "a");
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CheckCompare("ab", "ab");
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CheckCompare("abc", "abc");
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CheckCompare("abcd", "abcd");
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CheckCompare("abcde", "abcde");
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CheckCompare("a", "x");
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CheckCompare("ab", "xb");
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CheckCompare("abc", "xbc");
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CheckCompare("abcd", "xbcd");
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CheckCompare("abcde", "xbcde");
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CheckCompare("x", "a");
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CheckCompare("xb", "ab");
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CheckCompare("xbc", "abc");
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CheckCompare("xbcd", "abcd");
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CheckCompare("xbcde", "abcde");
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CheckCompare("a", "x");
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CheckCompare("ab", "ax");
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CheckCompare("abc", "abx");
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CheckCompare("abcd", "abcx");
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CheckCompare("abcde", "abcdx");
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CheckCompare("x", "a");
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CheckCompare("ax", "ab");
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CheckCompare("abx", "abc");
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CheckCompare("abcx", "abcd");
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CheckCompare("abcdx", "abcde");
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for (int len = 0; len < 1000; len++) {
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std::string p(len, 'z');
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CheckCompare(p + "x", p + "a");
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CheckCompare(p + "ax", p + "ab");
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CheckCompare(p + "abx", p + "abc");
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CheckCompare(p + "abcx", p + "abcd");
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CheckCompare(p + "abcdx", p + "abcde");
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}
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}
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TEST(FastCompare, TrailingByte) {
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for (int i = 0; i < 256; i++) {
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for (int j = 0; j < 256; j++) {
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std::string a(1, i);
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std::string b(1, j);
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CheckSingle(a, b);
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}
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}
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}
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// Check correctness of memcpy_inlined.
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void CheckSingleMemcpyInlined(const std::string& a) {
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std::unique_ptr<char[]> destination(new char[a.size() + 2]);
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destination[0] = 'x';
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destination[a.size() + 1] = 'x';
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absl::strings_internal::memcpy_inlined(destination.get() + 1, a.data(),
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a.size());
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CHECK_EQ('x', destination[0]);
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CHECK_EQ('x', destination[a.size() + 1]);
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CHECK_EQ(0, memcmp(a.data(), destination.get() + 1, a.size()));
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}
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TEST(MemCpyInlined, Misc) {
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CheckSingleMemcpyInlined("");
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CheckSingleMemcpyInlined("0");
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CheckSingleMemcpyInlined("012");
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CheckSingleMemcpyInlined("0123");
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CheckSingleMemcpyInlined("01234");
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CheckSingleMemcpyInlined("012345");
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CheckSingleMemcpyInlined("0123456");
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CheckSingleMemcpyInlined("01234567");
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CheckSingleMemcpyInlined("012345678");
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CheckSingleMemcpyInlined("0123456789");
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CheckSingleMemcpyInlined("0123456789a");
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CheckSingleMemcpyInlined("0123456789ab");
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CheckSingleMemcpyInlined("0123456789abc");
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CheckSingleMemcpyInlined("0123456789abcd");
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CheckSingleMemcpyInlined("0123456789abcde");
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CheckSingleMemcpyInlined("0123456789abcdef");
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CheckSingleMemcpyInlined("0123456789abcdefg");
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}
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template <typename Function>
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inline void CopyLoop(benchmark::State& state, int size, Function func) {
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char* src = new char[size];
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char* dst = new char[size];
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memset(src, 'x', size);
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memset(dst, 'y', size);
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for (auto _ : state) {
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func(dst, src, size);
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}
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state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * size);
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CHECK_EQ(dst[0], 'x');
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delete[] src;
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delete[] dst;
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}
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void BM_memcpy(benchmark::State& state) {
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CopyLoop(state, state.range(0), memcpy);
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}
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BENCHMARK(BM_memcpy)->DenseRange(1, 18)->Range(32, 8 << 20);
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void BM_memcpy_inlined(benchmark::State& state) {
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CopyLoop(state, state.range(0), absl::strings_internal::memcpy_inlined);
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}
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BENCHMARK(BM_memcpy_inlined)->DenseRange(1, 18)->Range(32, 8 << 20);
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// unaligned memcpy
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void BM_unaligned_memcpy(benchmark::State& state) {
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const int n = state.range(0);
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const int kMaxOffset = 32;
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char* src = new char[n + kMaxOffset];
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char* dst = new char[n + kMaxOffset];
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memset(src, 'x', n + kMaxOffset);
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int r = 0, i = 0;
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for (auto _ : state) {
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memcpy(dst + (i % kMaxOffset), src + ((i + 5) % kMaxOffset), n);
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r += dst[0];
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++i;
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}
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state.SetBytesProcessed(static_cast<int64_t>(state.iterations()) * n);
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delete[] src;
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delete[] dst;
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benchmark::DoNotOptimize(r);
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}
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BENCHMARK(BM_unaligned_memcpy)->DenseRange(1, 18)->Range(32, 8 << 20);
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// memmove worst case: heavy overlap, but not always by the same amount.
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// Also, the source and destination will often be unaligned.
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void BM_memmove_worst_case(benchmark::State& state) {
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||||
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
|
||||
Loading…
Add table
Add a link
Reference in a new issue