forked from OSchip/llvm-project
109 lines
2.9 KiB
C++
109 lines
2.9 KiB
C++
//===-- PerfHelper.h ------------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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(llvm::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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llvm::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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llvm::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(const 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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#ifdef HAVE_LIBPFM
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int FileDescriptor = -1;
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#endif
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};
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// Helper to measure a list of PerfEvent for a particular function.
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// callback is called for each successful measure (PerfEvent needs to be valid).
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template <typename Function>
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void Measure(
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llvm::ArrayRef<PerfEvent> Events,
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const std::function<void(const PerfEvent &Event, int64_t Value)> &Callback,
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Function Fn) {
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for (const auto &Event : Events) {
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if (!Event.valid())
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continue;
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Counter Cnt(Event);
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Cnt.start();
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Fn();
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Cnt.stop();
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Callback(Event, Cnt.read());
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}
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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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