Statistic.cpp revision 206083 
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/ManagedStatic.h"
28#include "llvm/Support/raw_ostream.h"
29#include "llvm/System/Mutex.h"
30#include "llvm/ADT/StringExtras.h"
31#include <algorithm>
32#include <cstring>
33using namespace llvm;
34
35// CreateInfoOutputFile - Return a file stream to print our output on.
36namespace llvm { extern raw_ostream *CreateInfoOutputFile(); }
37
38/// -stats - Command line option to cause transformations to emit stats about
39/// what they did.
40///
41static cl::opt<bool>
42Enabled("stats", cl::desc("Enable statistics output from program"));
43
44
45namespace {
46/// StatisticInfo - This class is used in a ManagedStatic so that it is created
47/// on demand (when the first statistic is bumped) and destroyed only when
48/// llvm_shutdown is called.  We print statistics from the destructor.
49class StatisticInfo {
50  std::vector<const Statistic*> Stats;
51  friend void llvm::PrintStatistics();
52  friend void llvm::PrintStatistics(raw_ostream &OS);
53public:
54  ~StatisticInfo();
55
56  void addStatistic(const Statistic *S) {
57    Stats.push_back(S);
58  }
59};
60}
61
62static ManagedStatic<StatisticInfo> StatInfo;
63static ManagedStatic<sys::SmartMutex<true> > StatLock;
64
65/// RegisterStatistic - The first time a statistic is bumped, this method is
66/// called.
67void Statistic::RegisterStatistic() {
68  // If stats are enabled, inform StatInfo that this statistic should be
69  // printed.
70  sys::SmartScopedLock<true> Writer(*StatLock);
71  if (!Initialized) {
72    if (Enabled)
73      StatInfo->addStatistic(this);
74
75    sys::MemoryFence();
76    // Remember we have been registered.
77    Initialized = true;
78  }
79}
80
81namespace {
82
83struct NameCompare {
84  bool operator()(const Statistic *LHS, const Statistic *RHS) const {
85    int Cmp = std::strcmp(LHS->getName(), RHS->getName());
86    if (Cmp != 0) return Cmp < 0;
87
88    // Secondary key is the description.
89    return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
90  }
91};
92
93}
94
95// Print information when destroyed, iff command line option is specified.
96StatisticInfo::~StatisticInfo() {
97  llvm::PrintStatistics();
98}
99
100void llvm::EnableStatistics() {
101  Enabled.setValue(true);
102}
103
104void llvm::PrintStatistics(raw_ostream &OS) {
105  StatisticInfo &Stats = *StatInfo;
106
107  // Figure out how long the biggest Value and Name fields are.
108  unsigned MaxNameLen = 0, MaxValLen = 0;
109  for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
110    MaxValLen = std::max(MaxValLen,
111                         (unsigned)utostr(Stats.Stats[i]->getValue()).size());
112    MaxNameLen = std::max(MaxNameLen,
113                          (unsigned)std::strlen(Stats.Stats[i]->getName()));
114  }
115
116  // Sort the fields by name.
117  std::stable_sort(Stats.Stats.begin(), Stats.Stats.end(), NameCompare());
118
119  // Print out the statistics header...
120  OS << "===" << std::string(73, '-') << "===\n"
121     << "                          ... Statistics Collected ...\n"
122     << "===" << std::string(73, '-') << "===\n\n";
123
124  // Print all of the statistics.
125  for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
126    std::string CountStr = utostr(Stats.Stats[i]->getValue());
127    OS << std::string(MaxValLen-CountStr.size(), ' ')
128       << CountStr << " " << Stats.Stats[i]->getName()
129       << std::string(MaxNameLen-std::strlen(Stats.Stats[i]->getName()), ' ')
130       << " - " << Stats.Stats[i]->getDesc() << "\n";
131  }
132
133  OS << '\n';  // Flush the output stream.
134  OS.flush();
135
136}
137
138void llvm::PrintStatistics() {
139  StatisticInfo &Stats = *StatInfo;
140
141  // Statistics not enabled?
142  if (Stats.Stats.empty()) return;
143
144  // Get the stream to write to.
145  raw_ostream &OutStream = *CreateInfoOutputFile();
146  PrintStatistics(OutStream);
147  delete &OutStream;   // Close the file.
148}
149