Statistic.cpp revision 198090 
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/raw_ostream.h"
28#include "llvm/System/Mutex.h"
29#include "llvm/ADT/StringExtras.h"
30#include <algorithm>
31#include <cstring>
32using namespace llvm;
33
34// GetLibSupportInfoOutputFile - Return a file stream to print our output on.
35namespace llvm { extern raw_ostream *GetLibSupportInfoOutputFile(); }
36
37/// -stats - Command line option to cause transformations to emit stats about
38/// what they did.
39///
40static cl::opt<bool>
41Enabled("stats", cl::desc("Enable statistics output from program"));
42
43
44namespace {
45/// StatisticInfo - This class is used in a ManagedStatic so that it is created
46/// on demand (when the first statistic is bumped) and destroyed only when
47/// llvm_shutdown is called.  We print statistics from the destructor.
48class StatisticInfo {
49  std::vector<const Statistic*> Stats;
50public:
51  ~StatisticInfo();
52
53  void addStatistic(const Statistic *S) {
54    Stats.push_back(S);
55  }
56};
57}
58
59static ManagedStatic<StatisticInfo> StatInfo;
60static ManagedStatic<sys::SmartMutex<true> > StatLock;
61
62/// RegisterStatistic - The first time a statistic is bumped, this method is
63/// called.
64void Statistic::RegisterStatistic() {
65  // If stats are enabled, inform StatInfo that this statistic should be
66  // printed.
67  sys::SmartScopedLock<true> Writer(*StatLock);
68  if (!Initialized) {
69    if (Enabled)
70      StatInfo->addStatistic(this);
71
72    sys::MemoryFence();
73    // Remember we have been registered.
74    Initialized = true;
75  }
76}
77
78namespace {
79
80struct NameCompare {
81  bool operator()(const Statistic *LHS, const Statistic *RHS) const {
82    int Cmp = std::strcmp(LHS->getName(), RHS->getName());
83    if (Cmp != 0) return Cmp < 0;
84
85    // Secondary key is the description.
86    return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
87  }
88};
89
90}
91
92// Print information when destroyed, iff command line option is specified.
93StatisticInfo::~StatisticInfo() {
94  // Statistics not enabled?
95  if (Stats.empty()) return;
96
97  // Get the stream to write to.
98  raw_ostream &OutStream = *GetLibSupportInfoOutputFile();
99
100  // Figure out how long the biggest Value and Name fields are.
101  unsigned MaxNameLen = 0, MaxValLen = 0;
102  for (size_t i = 0, e = Stats.size(); i != e; ++i) {
103    MaxValLen = std::max(MaxValLen,
104                         (unsigned)utostr(Stats[i]->getValue()).size());
105    MaxNameLen = std::max(MaxNameLen,
106                          (unsigned)std::strlen(Stats[i]->getName()));
107  }
108
109  // Sort the fields by name.
110  std::stable_sort(Stats.begin(), Stats.end(), NameCompare());
111
112  // Print out the statistics header...
113  OutStream << "===" << std::string(73, '-') << "===\n"
114            << "                          ... Statistics Collected ...\n"
115            << "===" << std::string(73, '-') << "===\n\n";
116
117  // Print all of the statistics.
118  for (size_t i = 0, e = Stats.size(); i != e; ++i) {
119    std::string CountStr = utostr(Stats[i]->getValue());
120    OutStream << std::string(MaxValLen-CountStr.size(), ' ')
121              << CountStr << " " << Stats[i]->getName()
122              << std::string(MaxNameLen-std::strlen(Stats[i]->getName()), ' ')
123              << " - " << Stats[i]->getDesc() << "\n";
124
125  }
126
127  OutStream << '\n';  // Flush the output stream...
128  OutStream.flush();
129
130  if (&OutStream != &outs() && &OutStream != &errs())
131    delete &OutStream;   // Close the file.
132}
133