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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
108 lines
3.0 KiB
C++
108 lines
3.0 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(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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