tvl-depot/absl/base/internal/cycleclock.cc

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// 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.
// The implementation of CycleClock::Frequency.
//
// NOTE: only i386 and x86_64 have been well tested.
// PPC, sparc, alpha, and ia64 are based on
// http://peter.kuscsik.com/wordpress/?p=14
// with modifications by m3b. See also
// https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h
#include "absl/base/internal/cycleclock.h"
Export of internal Abseil changes. -- 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 by Samuel Benzaquen <sbenza@google.com>: Fix uninitialized member in the `iterator` class by using a union of the two possible states of the iterator. This silences a Wuninitialized warning in gcc>=7. PiperOrigin-RevId: 228175148 -- 98b4e3204c0ec3cfd4cb037e24d443ea4b63fc84 by CJ Johnson <johnsoncj@google.com>: Factors out the implementation of InlinedVector::swap(...) into a private member function PiperOrigin-RevId: 228173383 -- f1432ad3a8b05285c6d55bc4754cfae765485b7f by Abseil Team <absl-team@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 227891984 -- 03fc00c7a4efc6000e6d9125cb2e252bffda76fe by Andy Getzendanner <durandal@google.com>: Add a missing linebreak to a comment and markdownify two unordered lists. PiperOrigin-RevId: 227861389 -- 0d66c9afba4fc9aa52e61d9fb410e165018a7b48 by Abseil Team <absl-team@google.com>: Add an API to register a new source for the cycle clock. PiperOrigin-RevId: 227779218 -- 14d3f9b70c8818b8541e5fb2f6ca4c59d479de31 by Andy Getzendanner <durandal@google.com>: Correct a typo in a stripping marker. PiperOrigin-RevId: 227750014 -- 59df88740f4e315beb57a8772f8bcf7879440c74 by Matt Kulukundis <kfm@google.com>: Switch thread local handling to be more cross platform PiperOrigin-RevId: 227695133 -- 75deed5bfcb5c42534e933f104aa7d94e11e348d by Abseil Team <absl-team@google.com>: Rollback workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227689133 -- 54994bf0afec026e6e0e7a199df0bbb4b7d9a4aa by Derek Mauro <dmauro@google.com>: Add -pthread to linkopts where it actually belongs, on the library that uses it. Fixes https://github.com/abseil/abseil-cpp/issues/240. PiperOrigin-RevId: 227612492 -- 893875f3536b7e0a1bad993aa6b2e083abb3b25a by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227582833 -- 506c9b8e9002ca3389c7040473b68d4cbf94bdcc by Matt Kulukundis <kfm@google.com>: Workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227561449 -- 29ee90d96dfe3114cf93f9bb92ea0cc9e768a407 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227054634 GitOrigin-RevId: 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 Change-Id: Ibc90566d92ee6e0ad7e150f513ec7f5d22ec0a94
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#include <atomic>
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#include <chrono> // NOLINT(build/c++11)
#include "absl/base/internal/unscaledcycleclock.h"
namespace absl {
namespace base_internal {
#if ABSL_USE_UNSCALED_CYCLECLOCK
namespace {
#ifdef NDEBUG
#ifdef ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY
// Not debug mode and the UnscaledCycleClock frequency is the CPU
// frequency. Scale the CycleClock to prevent overflow if someone
// tries to represent the time as cycles since the Unix epoch.
static constexpr int32_t kShift = 1;
#else
// Not debug mode and the UnscaledCycleClock isn't operating at the
// raw CPU frequency. There is no need to do any scaling, so don't
// needlessly sacrifice precision.
static constexpr int32_t kShift = 0;
#endif
#else
// In debug mode use a different shift to discourage depending on a
// particular shift value.
static constexpr int32_t kShift = 2;
#endif
static constexpr double kFrequencyScale = 1.0 / (1 << kShift);
Export of internal Abseil changes. -- 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 by Samuel Benzaquen <sbenza@google.com>: Fix uninitialized member in the `iterator` class by using a union of the two possible states of the iterator. This silences a Wuninitialized warning in gcc>=7. PiperOrigin-RevId: 228175148 -- 98b4e3204c0ec3cfd4cb037e24d443ea4b63fc84 by CJ Johnson <johnsoncj@google.com>: Factors out the implementation of InlinedVector::swap(...) into a private member function PiperOrigin-RevId: 228173383 -- f1432ad3a8b05285c6d55bc4754cfae765485b7f by Abseil Team <absl-team@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 227891984 -- 03fc00c7a4efc6000e6d9125cb2e252bffda76fe by Andy Getzendanner <durandal@google.com>: Add a missing linebreak to a comment and markdownify two unordered lists. PiperOrigin-RevId: 227861389 -- 0d66c9afba4fc9aa52e61d9fb410e165018a7b48 by Abseil Team <absl-team@google.com>: Add an API to register a new source for the cycle clock. PiperOrigin-RevId: 227779218 -- 14d3f9b70c8818b8541e5fb2f6ca4c59d479de31 by Andy Getzendanner <durandal@google.com>: Correct a typo in a stripping marker. PiperOrigin-RevId: 227750014 -- 59df88740f4e315beb57a8772f8bcf7879440c74 by Matt Kulukundis <kfm@google.com>: Switch thread local handling to be more cross platform PiperOrigin-RevId: 227695133 -- 75deed5bfcb5c42534e933f104aa7d94e11e348d by Abseil Team <absl-team@google.com>: Rollback workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227689133 -- 54994bf0afec026e6e0e7a199df0bbb4b7d9a4aa by Derek Mauro <dmauro@google.com>: Add -pthread to linkopts where it actually belongs, on the library that uses it. Fixes https://github.com/abseil/abseil-cpp/issues/240. PiperOrigin-RevId: 227612492 -- 893875f3536b7e0a1bad993aa6b2e083abb3b25a by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227582833 -- 506c9b8e9002ca3389c7040473b68d4cbf94bdcc by Matt Kulukundis <kfm@google.com>: Workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227561449 -- 29ee90d96dfe3114cf93f9bb92ea0cc9e768a407 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227054634 GitOrigin-RevId: 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 Change-Id: Ibc90566d92ee6e0ad7e150f513ec7f5d22ec0a94
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static std::atomic<CycleClockSourceFunc> cycle_clock_source;
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} // namespace
int64_t CycleClock::Now() {
Export of internal Abseil changes. -- 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 by Samuel Benzaquen <sbenza@google.com>: Fix uninitialized member in the `iterator` class by using a union of the two possible states of the iterator. This silences a Wuninitialized warning in gcc>=7. PiperOrigin-RevId: 228175148 -- 98b4e3204c0ec3cfd4cb037e24d443ea4b63fc84 by CJ Johnson <johnsoncj@google.com>: Factors out the implementation of InlinedVector::swap(...) into a private member function PiperOrigin-RevId: 228173383 -- f1432ad3a8b05285c6d55bc4754cfae765485b7f by Abseil Team <absl-team@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 227891984 -- 03fc00c7a4efc6000e6d9125cb2e252bffda76fe by Andy Getzendanner <durandal@google.com>: Add a missing linebreak to a comment and markdownify two unordered lists. PiperOrigin-RevId: 227861389 -- 0d66c9afba4fc9aa52e61d9fb410e165018a7b48 by Abseil Team <absl-team@google.com>: Add an API to register a new source for the cycle clock. PiperOrigin-RevId: 227779218 -- 14d3f9b70c8818b8541e5fb2f6ca4c59d479de31 by Andy Getzendanner <durandal@google.com>: Correct a typo in a stripping marker. PiperOrigin-RevId: 227750014 -- 59df88740f4e315beb57a8772f8bcf7879440c74 by Matt Kulukundis <kfm@google.com>: Switch thread local handling to be more cross platform PiperOrigin-RevId: 227695133 -- 75deed5bfcb5c42534e933f104aa7d94e11e348d by Abseil Team <absl-team@google.com>: Rollback workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227689133 -- 54994bf0afec026e6e0e7a199df0bbb4b7d9a4aa by Derek Mauro <dmauro@google.com>: Add -pthread to linkopts where it actually belongs, on the library that uses it. Fixes https://github.com/abseil/abseil-cpp/issues/240. PiperOrigin-RevId: 227612492 -- 893875f3536b7e0a1bad993aa6b2e083abb3b25a by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227582833 -- 506c9b8e9002ca3389c7040473b68d4cbf94bdcc by Matt Kulukundis <kfm@google.com>: Workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227561449 -- 29ee90d96dfe3114cf93f9bb92ea0cc9e768a407 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227054634 GitOrigin-RevId: 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 Change-Id: Ibc90566d92ee6e0ad7e150f513ec7f5d22ec0a94
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auto fn = cycle_clock_source.load(std::memory_order_relaxed);
if (fn == nullptr) {
return base_internal::UnscaledCycleClock::Now() >> kShift;
}
return fn() >> kShift;
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}
double CycleClock::Frequency() {
return kFrequencyScale * base_internal::UnscaledCycleClock::Frequency();
}
Export of internal Abseil changes. -- 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 by Samuel Benzaquen <sbenza@google.com>: Fix uninitialized member in the `iterator` class by using a union of the two possible states of the iterator. This silences a Wuninitialized warning in gcc>=7. PiperOrigin-RevId: 228175148 -- 98b4e3204c0ec3cfd4cb037e24d443ea4b63fc84 by CJ Johnson <johnsoncj@google.com>: Factors out the implementation of InlinedVector::swap(...) into a private member function PiperOrigin-RevId: 228173383 -- f1432ad3a8b05285c6d55bc4754cfae765485b7f by Abseil Team <absl-team@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 227891984 -- 03fc00c7a4efc6000e6d9125cb2e252bffda76fe by Andy Getzendanner <durandal@google.com>: Add a missing linebreak to a comment and markdownify two unordered lists. PiperOrigin-RevId: 227861389 -- 0d66c9afba4fc9aa52e61d9fb410e165018a7b48 by Abseil Team <absl-team@google.com>: Add an API to register a new source for the cycle clock. PiperOrigin-RevId: 227779218 -- 14d3f9b70c8818b8541e5fb2f6ca4c59d479de31 by Andy Getzendanner <durandal@google.com>: Correct a typo in a stripping marker. PiperOrigin-RevId: 227750014 -- 59df88740f4e315beb57a8772f8bcf7879440c74 by Matt Kulukundis <kfm@google.com>: Switch thread local handling to be more cross platform PiperOrigin-RevId: 227695133 -- 75deed5bfcb5c42534e933f104aa7d94e11e348d by Abseil Team <absl-team@google.com>: Rollback workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227689133 -- 54994bf0afec026e6e0e7a199df0bbb4b7d9a4aa by Derek Mauro <dmauro@google.com>: Add -pthread to linkopts where it actually belongs, on the library that uses it. Fixes https://github.com/abseil/abseil-cpp/issues/240. PiperOrigin-RevId: 227612492 -- 893875f3536b7e0a1bad993aa6b2e083abb3b25a by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227582833 -- 506c9b8e9002ca3389c7040473b68d4cbf94bdcc by Matt Kulukundis <kfm@google.com>: Workaround toolchain bug for incorrect handling of thread_local in inline functions PiperOrigin-RevId: 227561449 -- 29ee90d96dfe3114cf93f9bb92ea0cc9e768a407 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 227054634 GitOrigin-RevId: 5f1cf6547231f1b1daad6d1b785df6b0b999b3c9 Change-Id: Ibc90566d92ee6e0ad7e150f513ec7f5d22ec0a94
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void CycleClockSource::Register(CycleClockSourceFunc source) {
cycle_clock_source.store(source, std::memory_order_relaxed);
}
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#else
int64_t CycleClock::Now() {
return std::chrono::duration_cast<std::chrono::nanoseconds>(
std::chrono::steady_clock::now().time_since_epoch())
.count();
}
double CycleClock::Frequency() {
return 1e9;
}
#endif
} // namespace base_internal
} // namespace absl