base/internal/unscaledcycleclock_config.h

0001 // Copyright 2022 The Abseil Authors
0002 //
0003 // Licensed under the Apache License, Version 2.0 (the "License");
0004 // you may not use this file except in compliance with the License.
0005 // You may obtain a copy of the License at
0006 //
0007 //     https://www.apache.org/licenses/LICENSE-2.0
0008 //
0009 // Unless required by applicable law or agreed to in writing, software
0010 // distributed under the License is distributed on an "AS IS" BASIS,
0011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0012 // See the License for the specific language governing permissions and
0013 // limitations under the License.
0014
0015 #ifndef ABSL_BASE_INTERNAL_UNSCALEDCYCLECLOCK_CONFIG_H_
0016 #define ABSL_BASE_INTERNAL_UNSCALEDCYCLECLOCK_CONFIG_H_
0017
0018 #if defined(__APPLE__)
0019 #include <TargetConditionals.h>
0020 #endif
0021
0022 // The following platforms have an implementation of a hardware counter.
0023 #if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__) || \
0024     defined(__powerpc__) || defined(__ppc__) || defined(__riscv) ||     \
0025     defined(_M_IX86) || (defined(_M_X64) && !defined(_M_ARM64EC))
0026 #define ABSL_HAVE_UNSCALED_CYCLECLOCK_IMPLEMENTATION 1
0027 #else
0028 #define ABSL_HAVE_UNSCALED_CYCLECLOCK_IMPLEMENTATION 0
0029 #endif
0030
0031 // The following platforms often disable access to the hardware
0032 // counter (through a sandbox) even if the underlying hardware has a
0033 // usable counter. The CycleTimer interface also requires a *scaled*
0034 // CycleClock that runs at atleast 1 MHz. We've found some Android
0035 // ARM64 devices where this is not the case, so we disable it by
0036 // default on Android ARM64.
0037 #if defined(__native_client__) || (defined(__APPLE__)) || \
0038     (defined(__ANDROID__) && defined(__aarch64__))
0039 #define ABSL_USE_UNSCALED_CYCLECLOCK_DEFAULT 0
0040 #else
0041 #define ABSL_USE_UNSCALED_CYCLECLOCK_DEFAULT 1
0042 #endif
0043
0044 // UnscaledCycleClock is an optional internal feature.
0045 // Use "#if ABSL_USE_UNSCALED_CYCLECLOCK" to test for its presence.
0046 // Can be overridden at compile-time via -DABSL_USE_UNSCALED_CYCLECLOCK=0|1
0047 #if !defined(ABSL_USE_UNSCALED_CYCLECLOCK)
0048 #define ABSL_USE_UNSCALED_CYCLECLOCK               \
0049   (ABSL_HAVE_UNSCALED_CYCLECLOCK_IMPLEMENTATION && \
0050    ABSL_USE_UNSCALED_CYCLECLOCK_DEFAULT)
0051 #endif
0052
0053 #if ABSL_USE_UNSCALED_CYCLECLOCK
0054 // This macro can be used to test if UnscaledCycleClock::Frequency()
0055 // is NominalCPUFrequency() on a particular platform.
0056 #if (defined(__i386__) || defined(__x86_64__) || defined(__riscv) || \
0057      defined(_M_IX86) || defined(_M_X64))
0058 #define ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY
0059 #endif
0060 #endif
0061
0062 #endif  // ABSL_BASE_INTERNAL_UNSCALEDCYCLECLOCK_CONFIG_H_