1//===-- Statistic.cpp - Easy way to expose stats information --------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the 'Statistic' class, which is designed to be an easy
11// way to expose various success metrics from passes.  These statistics are
12// printed at the end of a run, when the -stats command line option is enabled
13// on the command line.
14//
15// This is useful for reporting information like the number of instructions
16// simplified, optimized or removed by various transformations, like this:
17//
18// static Statistic NumInstEliminated("GCSE", "Number of instructions killed");
19//
20// Later, in the code: ++NumInstEliminated;
21//
22//===----------------------------------------------------------------------===//
23
24#include "llvm/ADT/Statistic.h"
25#include "llvm/Support/CommandLine.h"
26#include "llvm/Support/Debug.h"
27#include "llvm/Support/Format.h"
28#include "llvm/Support/ManagedStatic.h"
29#include "llvm/Support/raw_ostream.h"
30#include "llvm/Support/Mutex.h"
31#include "llvm/ADT/StringExtras.h"
32#include <algorithm>
33#include <cstring>
34using namespace llvm;
35
36// CreateInfoOutputFile - Return a file stream to print our output on.
37namespace llvm { extern raw_ostream *CreateInfoOutputFile(); }
38
39/// -stats - Command line option to cause transformations to emit stats about
40/// what they did.
41///
42static cl::opt<bool>
43Enabled("stats", cl::desc("Enable statistics output from program"));
44
45
46namespace {
47/// StatisticInfo - This class is used in a ManagedStatic so that it is created
48/// on demand (when the first statistic is bumped) and destroyed only when
49/// llvm_shutdown is called.  We print statistics from the destructor.
50class StatisticInfo {
51  std::vector<const Statistic*> Stats;
52  friend void llvm::PrintStatistics();
53  friend void llvm::PrintStatistics(raw_ostream &OS);
54public:
55  ~StatisticInfo();
56
57  void addStatistic(const Statistic *S) {
58    Stats.push_back(S);
59  }
60};
61}
62
63static ManagedStatic<StatisticInfo> StatInfo;
64static ManagedStatic<sys::SmartMutex<true> > StatLock;
65
66/// RegisterStatistic - The first time a statistic is bumped, this method is
67/// called.
68void Statistic::RegisterStatistic() {
69  // If stats are enabled, inform StatInfo that this statistic should be
70  // printed.
71  sys::SmartScopedLock<true> Writer(*StatLock);
72  if (!Initialized) {
73    if (Enabled)
74      StatInfo->addStatistic(this);
75
76    TsanHappensBefore(this);
77    sys::MemoryFence();
78    // Remember we have been registered.
79    TsanIgnoreWritesBegin();
80    Initialized = true;
81    TsanIgnoreWritesEnd();
82  }
83}
84
85namespace {
86
87struct NameCompare {
88  bool operator()(const Statistic *LHS, const Statistic *RHS) const {
89    int Cmp = std::strcmp(LHS->getName(), RHS->getName());
90    if (Cmp != 0) return Cmp < 0;
91
92    // Secondary key is the description.
93    return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
94  }
95};
96
97}
98
99// Print information when destroyed, iff command line option is specified.
100StatisticInfo::~StatisticInfo() {
101  llvm::PrintStatistics();
102}
103
104void llvm::EnableStatistics() {
105  Enabled.setValue(true);
106}
107
108bool llvm::AreStatisticsEnabled() {
109  return Enabled;
110}
111
112void llvm::PrintStatistics(raw_ostream &OS) {
113  StatisticInfo &Stats = *StatInfo;
114
115  // Figure out how long the biggest Value and Name fields are.
116  unsigned MaxNameLen = 0, MaxValLen = 0;
117  for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
118    MaxValLen = std::max(MaxValLen,
119                         (unsigned)utostr(Stats.Stats[i]->getValue()).size());
120    MaxNameLen = std::max(MaxNameLen,
121                          (unsigned)std::strlen(Stats.Stats[i]->getName()));
122  }
123
124  // Sort the fields by name.
125  std::stable_sort(Stats.Stats.begin(), Stats.Stats.end(), NameCompare());
126
127  // Print out the statistics header...
128  OS << "===" << std::string(73, '-') << "===\n"
129     << "                          ... Statistics Collected ...\n"
130     << "===" << std::string(73, '-') << "===\n\n";
131
132  // Print all of the statistics.
133  for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i)
134    OS << format("%*u %-*s - %s\n",
135                 MaxValLen, Stats.Stats[i]->getValue(),
136                 MaxNameLen, Stats.Stats[i]->getName(),
137                 Stats.Stats[i]->getDesc());
138
139  OS << '\n';  // Flush the output stream.
140  OS.flush();
141
142}
143
144void llvm::PrintStatistics() {
145  StatisticInfo &Stats = *StatInfo;
146
147  // Statistics not enabled?
148  if (Stats.Stats.empty()) return;
149
150  // Get the stream to write to.
151  raw_ostream &OutStream = *CreateInfoOutputFile();
152  PrintStatistics(OutStream);
153  delete &OutStream;   // Close the file.
154}
155