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comparison tools/llvm-exegesis/lib/PerfHelper.h @ 147:c2174574ed3a

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LLVM 10
author Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date Wed, 14 Aug 2019 16:55:33 +0900
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134:3a76565eade5 147:c2174574ed3a
1 //===-- PerfHelper.h ------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// Helpers for measuring perf events.
11 ///
12 //===----------------------------------------------------------------------===//
13
14 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H
15 #define LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H
16
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/Config/config.h"
20 #include <functional>
21 #include <memory>
22
23 struct perf_event_attr;
24
25 namespace llvm {
26 namespace exegesis {
27 namespace pfm {
28
29 // Returns true on error.
30 bool pfmInitialize();
31 void pfmTerminate();
32
33 // Retrieves the encoding for the event described by pfm_event_string.
34 // NOTE: pfm_initialize() must be called before creating PerfEvent objects.
35 class PerfEvent {
36 public:
37 // http://perfmon2.sourceforge.net/manv4/libpfm.html
38 // Events are expressed as strings. e.g. "INSTRUCTION_RETIRED"
39 explicit PerfEvent(llvm::StringRef pfm_event_string);
40
41 PerfEvent(const PerfEvent &) = delete;
42 PerfEvent(PerfEvent &&other);
43 ~PerfEvent();
44
45 // The pfm_event_string passed at construction time.
46 llvm::StringRef name() const;
47
48 // Whether the event was successfully created.
49 bool valid() const;
50
51 // The encoded event to be passed to the Kernel.
52 const perf_event_attr *attribute() const;
53
54 // The fully qualified name for the event.
55 // e.g. "snb_ep::INSTRUCTION_RETIRED:e=0:i=0:c=0:t=0:u=1:k=0:mg=0:mh=1"
56 llvm::StringRef getPfmEventString() const;
57
58 private:
59 const std::string EventString;
60 std::string FullQualifiedEventString;
61 perf_event_attr *Attr;
62 };
63
64 // Uses a valid PerfEvent to configure the Kernel so we can measure the
65 // underlying event.
66 struct Counter {
67 // event: the PerfEvent to measure.
68 explicit Counter(const PerfEvent &event);
69
70 Counter(const Counter &) = delete;
71 Counter(Counter &&other) = default;
72
73 ~Counter();
74
75 void start(); // Starts the measurement of the event.
76 void stop(); // Stops the measurement of the event.
77 int64_t read() const; // Return the current value of the counter.
78
79 private:
80 #ifdef HAVE_LIBPFM
81 int FileDescriptor = -1;
82 #endif
83 };
84
85 // Helper to measure a list of PerfEvent for a particular function.
86 // callback is called for each successful measure (PerfEvent needs to be valid).
87 template <typename Function>
88 void Measure(
89 llvm::ArrayRef<PerfEvent> Events,
90 const std::function<void(const PerfEvent &Event, int64_t Value)> &Callback,
91 Function Fn) {
92 for (const auto &Event : Events) {
93 if (!Event.valid())
94 continue;
95 Counter Cnt(Event);
96 Cnt.start();
97 Fn();
98 Cnt.stop();
99 Callback(Event, Cnt.read());
100 }
101 }
102
103 } // namespace pfm
104 } // namespace exegesis
105 } // namespace llvm
106
107 #endif // LLVM_TOOLS_LLVM_EXEGESIS_PERFHELPER_H