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/ADT/StringExtras.h"
26 #include "llvm/Support/CommandLine.h"
27 #include "llvm/Support/Compiler.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/Support/Format.h"
30 #include "llvm/Support/ManagedStatic.h"
31 #include "llvm/Support/Mutex.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include <algorithm>
34 #include <cstring>
35 using namespace llvm;
36
37 /// -stats - Command line option to cause transformations to emit stats about
38 /// what they did.
39 ///
40 static cl::opt<bool>
41 Enabled(
42 "stats",
43 cl::desc("Enable statistics output from program (available with Asserts)"));
44
45
46 static cl::opt<bool> StatsAsJSON("stats-json",
47 cl::desc("Display statistics as json data"));
48
49 namespace {
50 /// StatisticInfo - This class is used in a ManagedStatic so that it is created
51 /// on demand (when the first statistic is bumped) and destroyed only when
52 /// llvm_shutdown is called. We print statistics from the destructor.
53 class StatisticInfo {
54 std::vector<const Statistic*> Stats;
55 friend void llvm::PrintStatistics();
56 friend void llvm::PrintStatistics(raw_ostream &OS);
57 friend void llvm::PrintStatisticsJSON(raw_ostream &OS);
58
59 /// Sort statistics by debugtype,name,description.
60 void sort();
61 public:
62 ~StatisticInfo();
63
addStatistic(const Statistic * S)64 void addStatistic(const Statistic *S) {
65 Stats.push_back(S);
66 }
67 };
68 }
69
70 static ManagedStatic<StatisticInfo> StatInfo;
71 static ManagedStatic<sys::SmartMutex<true> > StatLock;
72
73 /// RegisterStatistic - The first time a statistic is bumped, this method is
74 /// called.
RegisterStatistic()75 void Statistic::RegisterStatistic() {
76 // If stats are enabled, inform StatInfo that this statistic should be
77 // printed.
78 sys::SmartScopedLock<true> Writer(*StatLock);
79 if (!Initialized) {
80 if (Enabled)
81 StatInfo->addStatistic(this);
82
83 TsanHappensBefore(this);
84 sys::MemoryFence();
85 // Remember we have been registered.
86 TsanIgnoreWritesBegin();
87 Initialized = true;
88 TsanIgnoreWritesEnd();
89 }
90 }
91
92 // Print information when destroyed, iff command line option is specified.
~StatisticInfo()93 StatisticInfo::~StatisticInfo() {
94 llvm::PrintStatistics();
95 }
96
EnableStatistics()97 void llvm::EnableStatistics() {
98 Enabled.setValue(true);
99 }
100
AreStatisticsEnabled()101 bool llvm::AreStatisticsEnabled() {
102 return Enabled;
103 }
104
sort()105 void StatisticInfo::sort() {
106 std::stable_sort(Stats.begin(), Stats.end(),
107 [](const Statistic *LHS, const Statistic *RHS) {
108 if (int Cmp = std::strcmp(LHS->getDebugType(), RHS->getDebugType()))
109 return Cmp < 0;
110
111 if (int Cmp = std::strcmp(LHS->getName(), RHS->getName()))
112 return Cmp < 0;
113
114 return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
115 });
116 }
117
PrintStatistics(raw_ostream & OS)118 void llvm::PrintStatistics(raw_ostream &OS) {
119 StatisticInfo &Stats = *StatInfo;
120
121 // Figure out how long the biggest Value and Name fields are.
122 unsigned MaxDebugTypeLen = 0, MaxValLen = 0;
123 for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
124 MaxValLen = std::max(MaxValLen,
125 (unsigned)utostr(Stats.Stats[i]->getValue()).size());
126 MaxDebugTypeLen = std::max(MaxDebugTypeLen,
127 (unsigned)std::strlen(Stats.Stats[i]->getDebugType()));
128 }
129
130 Stats.sort();
131
132 // Print out the statistics header...
133 OS << "===" << std::string(73, '-') << "===\n"
134 << " ... Statistics Collected ...\n"
135 << "===" << std::string(73, '-') << "===\n\n";
136
137 // Print all of the statistics.
138 for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i)
139 OS << format("%*u %-*s - %s\n",
140 MaxValLen, Stats.Stats[i]->getValue(),
141 MaxDebugTypeLen, Stats.Stats[i]->getDebugType(),
142 Stats.Stats[i]->getDesc());
143
144 OS << '\n'; // Flush the output stream.
145 OS.flush();
146 }
147
write_json_string_escaped(raw_ostream & OS,const char * string)148 static void write_json_string_escaped(raw_ostream &OS, const char *string) {
149 // Out current usage should not need any escaping. Keep it simple and just
150 // check that the input is pure ASCII without special characers.
151 #ifndef NDEBUG
152 for (const unsigned char *c = (const unsigned char*)string; *c != '\0'; ++c) {
153 assert(*c != '\\' && *c != '\"' && *c >= 0x20 && *c < 0x80);
154 }
155 #endif
156 OS << string;
157 }
158
PrintStatisticsJSON(raw_ostream & OS)159 void llvm::PrintStatisticsJSON(raw_ostream &OS) {
160 StatisticInfo &Stats = *StatInfo;
161
162 Stats.sort();
163
164 // Print all of the statistics.
165 OS << "{\n";
166 const char *delim = "";
167 for (const Statistic *Stat : Stats.Stats) {
168 OS << delim;
169 OS << "\t\"";
170 write_json_string_escaped(OS, Stat->getDebugType());
171 OS << '.';
172 write_json_string_escaped(OS, Stat->getName());
173 OS << "\": " << Stat->getValue();
174 delim = ",\n";
175 }
176 OS << "\n}\n";
177 OS.flush();
178 }
179
PrintStatistics()180 void llvm::PrintStatistics() {
181 #if !defined(NDEBUG) || defined(LLVM_ENABLE_STATS)
182 StatisticInfo &Stats = *StatInfo;
183
184 // Statistics not enabled?
185 if (Stats.Stats.empty()) return;
186
187 // Get the stream to write to.
188 std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
189 if (StatsAsJSON)
190 PrintStatisticsJSON(*OutStream);
191 else
192 PrintStatistics(*OutStream);
193
194 #else
195 // Check if the -stats option is set instead of checking
196 // !Stats.Stats.empty(). In release builds, Statistics operators
197 // do nothing, so stats are never Registered.
198 if (Enabled) {
199 // Get the stream to write to.
200 std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
201 (*OutStream) << "Statistics are disabled. "
202 << "Build with asserts or with -DLLVM_ENABLE_STATS\n";
203 }
204 #endif
205 }
206