Statistic.cpp revision 194710 
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/ManagedStatic.h"
27#include "llvm/Support/Streams.h"
28#include "llvm/System/Mutex.h"
29#include "llvm/ADT/StringExtras.h"
30#include <algorithm>
31#include <ostream>
32#include <cstring>
33using namespace llvm;
34
35// GetLibSupportInfoOutputFile - Return a file stream to print our output on.
36namespace llvm { extern std::ostream *GetLibSupportInfoOutputFile(); }
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;
51public:
52  ~StatisticInfo();
53
54  void addStatistic(const Statistic *S) {
55    Stats.push_back(S);
56  }
57};
58}
59
60static ManagedStatic<StatisticInfo> StatInfo;
61static ManagedStatic<sys::Mutex> StatLock;
62
63/// RegisterStatistic - The first time a statistic is bumped, this method is
64/// called.
65void Statistic::RegisterStatistic() {
66  // If stats are enabled, inform StatInfo that this statistic should be
67  // printed.
68  sys::ScopedLock Writer(&*StatLock);
69  if (Enabled)
70    StatInfo->addStatistic(this);
71  // Remember we have been registered.
72  Initialized = true;
73}
74
75namespace {
76
77struct NameCompare {
78  bool operator()(const Statistic *LHS, const Statistic *RHS) const {
79    int Cmp = std::strcmp(LHS->getName(), RHS->getName());
80    if (Cmp != 0) return Cmp < 0;
81
82    // Secondary key is the description.
83    return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
84  }
85};
86
87}
88
89// Print information when destroyed, iff command line option is specified.
90StatisticInfo::~StatisticInfo() {
91  // Statistics not enabled?
92  if (Stats.empty()) return;
93
94  // Get the stream to write to.
95  std::ostream &OutStream = *GetLibSupportInfoOutputFile();
96
97  // Figure out how long the biggest Value and Name fields are.
98  unsigned MaxNameLen = 0, MaxValLen = 0;
99  for (size_t i = 0, e = Stats.size(); i != e; ++i) {
100    MaxValLen = std::max(MaxValLen,
101                         (unsigned)utostr(Stats[i]->getValue()).size());
102    MaxNameLen = std::max(MaxNameLen,
103                          (unsigned)std::strlen(Stats[i]->getName()));
104  }
105
106  // Sort the fields by name.
107  std::stable_sort(Stats.begin(), Stats.end(), NameCompare());
108
109  // Print out the statistics header...
110  OutStream << "===" << std::string(73, '-') << "===\n"
111            << "                          ... Statistics Collected ...\n"
112            << "===" << std::string(73, '-') << "===\n\n";
113
114  // Print all of the statistics.
115  for (size_t i = 0, e = Stats.size(); i != e; ++i) {
116    std::string CountStr = utostr(Stats[i]->getValue());
117    OutStream << std::string(MaxValLen-CountStr.size(), ' ')
118              << CountStr << " " << Stats[i]->getName()
119              << std::string(MaxNameLen-std::strlen(Stats[i]->getName()), ' ')
120              << " - " << Stats[i]->getDesc() << "\n";
121
122  }
123
124  OutStream << std::endl;  // Flush the output stream...
125
126  if (&OutStream != cerr.stream() && &OutStream != cout.stream())
127    delete &OutStream;   // Close the file.
128}
129