fc8dc48020
git-subtree-dir: third_party/abseil_cpp git-subtree-mainline:ffb2ae54begit-subtree-split:768eb2ca28
140 lines
3.5 KiB
C++
140 lines
3.5 KiB
C++
// 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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// 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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#include "absl/base/internal/unscaledcycleclock.h"
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#if ABSL_USE_UNSCALED_CYCLECLOCK
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#if defined(_WIN32)
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#include <intrin.h>
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#endif
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#if defined(__powerpc__) || defined(__ppc__)
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#ifdef __GLIBC__
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#include <sys/platform/ppc.h>
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#elif defined(__FreeBSD__)
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#include <sys/sysctl.h>
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#include <sys/types.h>
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#endif
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#endif
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#include "absl/base/internal/sysinfo.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 defined(__i386__)
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int64_t UnscaledCycleClock::Now() {
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int64_t ret;
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__asm__ volatile("rdtsc" : "=A"(ret));
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return ret;
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}
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double UnscaledCycleClock::Frequency() {
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return base_internal::NominalCPUFrequency();
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}
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#elif defined(__x86_64__)
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int64_t UnscaledCycleClock::Now() {
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uint64_t low, high;
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__asm__ volatile("rdtsc" : "=a"(low), "=d"(high));
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return (high << 32) | low;
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}
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double UnscaledCycleClock::Frequency() {
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return base_internal::NominalCPUFrequency();
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}
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#elif defined(__powerpc__) || defined(__ppc__)
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int64_t UnscaledCycleClock::Now() {
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#ifdef __GLIBC__
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return __ppc_get_timebase();
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#else
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#ifdef __powerpc64__
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int64_t tbr;
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asm volatile("mfspr %0, 268" : "=r"(tbr));
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return tbr;
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#else
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int32_t tbu, tbl, tmp;
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asm volatile(
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"0:\n"
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"mftbu %[hi32]\n"
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"mftb %[lo32]\n"
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"mftbu %[tmp]\n"
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"cmpw %[tmp],%[hi32]\n"
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"bne 0b\n"
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: [ hi32 ] "=r"(tbu), [ lo32 ] "=r"(tbl), [ tmp ] "=r"(tmp));
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return (static_cast<int64_t>(tbu) << 32) | tbl;
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#endif
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#endif
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}
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double UnscaledCycleClock::Frequency() {
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#ifdef __GLIBC__
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return __ppc_get_timebase_freq();
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#elif defined(__FreeBSD__)
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static once_flag init_timebase_frequency_once;
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static double timebase_frequency = 0.0;
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base_internal::LowLevelCallOnce(&init_timebase_frequency_once, [&]() {
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size_t length = sizeof(timebase_frequency);
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sysctlbyname("kern.timecounter.tc.timebase.frequency", &timebase_frequency,
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&length, nullptr, 0);
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});
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return timebase_frequency;
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#else
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#error Must implement UnscaledCycleClock::Frequency()
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#endif
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}
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#elif defined(__aarch64__)
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// System timer of ARMv8 runs at a different frequency than the CPU's.
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// The frequency is fixed, typically in the range 1-50MHz. It can be
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// read at CNTFRQ special register. We assume the OS has set up
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// the virtual timer properly.
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int64_t UnscaledCycleClock::Now() {
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int64_t virtual_timer_value;
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asm volatile("mrs %0, cntvct_el0" : "=r"(virtual_timer_value));
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return virtual_timer_value;
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}
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double UnscaledCycleClock::Frequency() {
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uint64_t aarch64_timer_frequency;
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asm volatile("mrs %0, cntfrq_el0" : "=r"(aarch64_timer_frequency));
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return aarch64_timer_frequency;
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}
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#elif defined(_M_IX86) || defined(_M_X64)
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#pragma intrinsic(__rdtsc)
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int64_t UnscaledCycleClock::Now() {
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return __rdtsc();
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}
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double UnscaledCycleClock::Frequency() {
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return base_internal::NominalCPUFrequency();
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}
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#endif
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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_USE_UNSCALED_CYCLECLOCK
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