9fb871866e
A perf helper is always only ever cretaed to be checked for validity then passed as Counter ctor argument, never to be touched again. Its lifetime should outlive that of the counter, and there is never any reason to have two different counters of top of the perf helper. Make sure these assumptions always hold by making the Counter consume the PerfHelper.
91 lines
2.5 KiB
C++
91 lines
2.5 KiB
C++
//===-- PerfHelper.h ------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// Helpers for measuring perf events.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H
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#define LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Config/config.h"
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#include <functional>
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#include <memory>
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struct perf_event_attr;
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namespace llvm {
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namespace exegesis {
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namespace pfm {
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// Returns true on error.
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bool pfmInitialize();
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void pfmTerminate();
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// Retrieves the encoding for the event described by pfm_event_string.
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// NOTE: pfm_initialize() must be called before creating PerfEvent objects.
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class PerfEvent {
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public:
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// http://perfmon2.sourceforge.net/manv4/libpfm.html
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// Events are expressed as strings. e.g. "INSTRUCTION_RETIRED"
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explicit PerfEvent(StringRef pfm_event_string);
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PerfEvent(const PerfEvent &) = delete;
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PerfEvent(PerfEvent &&other);
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~PerfEvent();
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// The pfm_event_string passed at construction time.
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StringRef name() const;
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// Whether the event was successfully created.
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bool valid() const;
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// The encoded event to be passed to the Kernel.
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const perf_event_attr *attribute() const;
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// The fully qualified name for the event.
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// e.g. "snb_ep::INSTRUCTION_RETIRED:e=0:i=0:c=0:t=0:u=1:k=0:mg=0:mh=1"
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StringRef getPfmEventString() const;
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private:
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const std::string EventString;
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std::string FullQualifiedEventString;
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perf_event_attr *Attr;
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};
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// Uses a valid PerfEvent to configure the Kernel so we can measure the
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// underlying event.
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struct Counter {
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// event: the PerfEvent to measure.
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explicit Counter(PerfEvent &&event);
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Counter(const Counter &) = delete;
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Counter(Counter &&other) = default;
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~Counter();
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void start(); // Starts the measurement of the event.
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void stop(); // Stops the measurement of the event.
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int64_t read() const; // Return the current value of the counter.
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private:
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PerfEvent Event;
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#ifdef HAVE_LIBPFM
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int FileDescriptor = -1;
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#endif
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};
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} // namespace pfm
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} // namespace exegesis
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} // namespace llvm
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#endif // LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H
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