PiperOrigin-RevId: 477043101 Change-Id: I009ea39ad61e7e78cdac51afc57a8ad5b4d8aa2dpull/1283/head
Abseil Team
3 years ago
committed by
Copybara-Service
parent
1cd889767e
commit
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7 changed files with 144 additions and 57 deletions
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// Copyright 2022 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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// https://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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#ifndef ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_ |
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#define ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_ |
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#include <cstdint> |
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#include "absl/base/config.h" |
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#include "absl/base/internal/inline_variable.h" |
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#include "absl/base/internal/unscaledcycleclock_config.h" |
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namespace absl { |
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ABSL_NAMESPACE_BEGIN |
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namespace base_internal { |
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#if ABSL_USE_UNSCALED_CYCLECLOCK |
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#ifdef NDEBUG |
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#ifdef ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY |
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// Not debug mode and the UnscaledCycleClock frequency is the CPU
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// frequency. Scale the CycleClock to prevent overflow if someone
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// tries to represent the time as cycles since the Unix epoch.
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ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 1); |
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#else |
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// Not debug mode and the UnscaledCycleClock isn't operating at the
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// raw CPU frequency. There is no need to do any scaling, so don't
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// needlessly sacrifice precision.
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ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 0); |
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#endif |
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#else // NDEBUG
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// In debug mode use a different shift to discourage depending on a
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// particular shift value.
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ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 2); |
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#endif // NDEBUG
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ABSL_INTERNAL_INLINE_CONSTEXPR(double, kCycleClockFrequencyScale, |
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1.0 / (1 << kCycleClockShift)); |
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#endif // ABSL_USE_UNSCALED_CYCLECLOC
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} // namespace base_internal
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ABSL_NAMESPACE_END |
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} // namespace absl
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#endif // ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_
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// Copyright 2022 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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// https://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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#ifndef ABSL_BASE_INTERNAL_UNSCALEDCYCLECLOCK_CONFIG_H_ |
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#define ABSL_BASE_INTERNAL_UNSCALEDCYCLECLOCK_CONFIG_H_ |
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#if defined(__APPLE__) |
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#include <TargetConditionals.h> |
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#endif |
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// The following platforms have an implementation of a hardware counter.
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#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__) || \ |
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defined(__powerpc__) || defined(__ppc__) || defined(__riscv) || \
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defined(_M_IX86) || (defined(_M_X64) && !defined(_M_ARM64EC)) |
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#define ABSL_HAVE_UNSCALED_CYCLECLOCK_IMPLEMENTATION 1 |
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#else |
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#define ABSL_HAVE_UNSCALED_CYCLECLOCK_IMPLEMENTATION 0 |
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#endif |
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// The following platforms often disable access to the hardware
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// counter (through a sandbox) even if the underlying hardware has a
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// usable counter. The CycleTimer interface also requires a *scaled*
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// CycleClock that runs at atleast 1 MHz. We've found some Android
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// ARM64 devices where this is not the case, so we disable it by
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// default on Android ARM64.
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#if defined(__native_client__) || (defined(__APPLE__)) || \ |
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(defined(__ANDROID__) && defined(__aarch64__)) |
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#define ABSL_USE_UNSCALED_CYCLECLOCK_DEFAULT 0 |
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#else |
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#define ABSL_USE_UNSCALED_CYCLECLOCK_DEFAULT 1 |
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#endif |
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// UnscaledCycleClock is an optional internal feature.
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// Use "#if ABSL_USE_UNSCALED_CYCLECLOCK" to test for its presence.
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// Can be overridden at compile-time via -DABSL_USE_UNSCALED_CYCLECLOCK=0|1
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#if !defined(ABSL_USE_UNSCALED_CYCLECLOCK) |
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#define ABSL_USE_UNSCALED_CYCLECLOCK \ |
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(ABSL_HAVE_UNSCALED_CYCLECLOCK_IMPLEMENTATION && \
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ABSL_USE_UNSCALED_CYCLECLOCK_DEFAULT) |
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#endif |
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#if ABSL_USE_UNSCALED_CYCLECLOCK |
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// This macro can be used to test if UnscaledCycleClock::Frequency()
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// is NominalCPUFrequency() on a particular platform.
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#if (defined(__i386__) || defined(__x86_64__) || defined(__riscv) || \ |
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defined(_M_IX86) || defined(_M_X64)) |
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#define ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY |
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#endif |
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#endif |
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#endif // ABSL_BASE_INTERNAL_UNSCALEDCYCLECLOCK_CONFIG_H_
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