60 lines
1.8 KiB
C++
60 lines
1.8 KiB
C++
// Copyright 2019 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TRACE_EVENT_THREAD_INSTRUCTION_COUNT_H_
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#define BASE_TRACE_EVENT_THREAD_INSTRUCTION_COUNT_H_
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#include <stdint.h>
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#include "base/base_export.h"
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namespace base {
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namespace trace_event {
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// Represents the number of instructions that were retired between two samples
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// of a thread's performance counters.
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class BASE_EXPORT ThreadInstructionDelta {
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public:
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constexpr ThreadInstructionDelta() : delta_(0) {}
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explicit constexpr ThreadInstructionDelta(int64_t delta) : delta_(delta) {}
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constexpr int64_t ToInternalValue() const { return delta_; }
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private:
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int64_t delta_;
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};
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// Uses the system's performance counters in order to measure the number of
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// instructions that have been retired on the current thread.
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class BASE_EXPORT ThreadInstructionCount {
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public:
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// Returns true if the platform supports hardware retired instruction
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// counters.
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static bool IsSupported();
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// Returns the number of retired instructions relative to some epoch count,
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// or -1 if getting the current instruction count failed / is disabled.
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static ThreadInstructionCount Now();
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constexpr ThreadInstructionCount() : value_(-1) {}
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explicit constexpr ThreadInstructionCount(int64_t value) : value_(value) {}
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constexpr bool is_null() const { return value_ == -1; }
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constexpr ThreadInstructionDelta operator-(
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ThreadInstructionCount other) const {
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return ThreadInstructionDelta(value_ - other.value_);
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}
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constexpr int64_t ToInternalValue() const { return value_; }
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private:
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int64_t value_;
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};
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} // namespace trace_event
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} // namespace base
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#endif // BASE_TRACE_EVENT_THREAD_INSTRUCTION_COUNT_H_
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