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> Stats("stats",
41     cl::desc("Enable statistics output from program (available with Asserts)"));
42 
43 
44 static cl::opt<bool> StatsAsJSON("stats-json",
45                                  cl::desc("Display statistics as json data"));
46 
47 static bool Enabled;
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 
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.
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 (Stats || 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.
93 StatisticInfo::~StatisticInfo() {
94   if (::Stats)
95     llvm::PrintStatistics();
96 }
97 
98 void llvm::EnableStatistics() {
99   Enabled = true;
100 }
101 
102 bool llvm::AreStatisticsEnabled() {
103   return Enabled || Stats;
104 }
105 
106 void StatisticInfo::sort() {
107   std::stable_sort(Stats.begin(), Stats.end(),
108                    [](const Statistic *LHS, const Statistic *RHS) {
109     if (int Cmp = std::strcmp(LHS->getDebugType(), RHS->getDebugType()))
110       return Cmp < 0;
111 
112     if (int Cmp = std::strcmp(LHS->getName(), RHS->getName()))
113       return Cmp < 0;
114 
115     return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
116   });
117 }
118 
119 void llvm::PrintStatistics(raw_ostream &OS) {
120   StatisticInfo &Stats = *StatInfo;
121 
122   // Figure out how long the biggest Value and Name fields are.
123   unsigned MaxDebugTypeLen = 0, MaxValLen = 0;
124   for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
125     MaxValLen = std::max(MaxValLen,
126                          (unsigned)utostr(Stats.Stats[i]->getValue()).size());
127     MaxDebugTypeLen = std::max(MaxDebugTypeLen,
128                          (unsigned)std::strlen(Stats.Stats[i]->getDebugType()));
129   }
130 
131   Stats.sort();
132 
133   // Print out the statistics header...
134   OS << "===" << std::string(73, '-') << "===\n"
135      << "                          ... Statistics Collected ...\n"
136      << "===" << std::string(73, '-') << "===\n\n";
137 
138   // Print all of the statistics.
139   for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i)
140     OS << format("%*u %-*s - %s\n",
141                  MaxValLen, Stats.Stats[i]->getValue(),
142                  MaxDebugTypeLen, Stats.Stats[i]->getDebugType(),
143                  Stats.Stats[i]->getDesc());
144 
145   OS << '\n';  // Flush the output stream.
146   OS.flush();
147 }
148 
149 static void write_json_string_escaped(raw_ostream &OS, const char *string) {
150   // Out current usage should not need any escaping. Keep it simple and just
151   // check that the input is pure ASCII without special characers.
152 #ifndef NDEBUG
153   for (const unsigned char *c = (const unsigned char*)string; *c != '\0'; ++c) {
154     assert(*c != '\\' && *c != '\"' && *c >= 0x20 && *c < 0x80);
155   }
156 #endif
157   OS << string;
158 }
159 
160 void llvm::PrintStatisticsJSON(raw_ostream &OS) {
161   StatisticInfo &Stats = *StatInfo;
162 
163   Stats.sort();
164 
165   // Print all of the statistics.
166   OS << "{\n";
167   const char *delim = "";
168   for (const Statistic *Stat : Stats.Stats) {
169     OS << delim;
170     OS << "\t\"";
171     write_json_string_escaped(OS, Stat->getDebugType());
172     OS << '.';
173     write_json_string_escaped(OS, Stat->getName());
174     OS << "\": " << Stat->getValue();
175     delim = ",\n";
176   }
177   OS << "\n}\n";
178   OS.flush();
179 }
180 
181 void llvm::PrintStatistics() {
182 #if !defined(NDEBUG) || defined(LLVM_ENABLE_STATS)
183   StatisticInfo &Stats = *StatInfo;
184 
185   // Statistics not enabled?
186   if (Stats.Stats.empty()) return;
187 
188   // Get the stream to write to.
189   std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
190   if (StatsAsJSON)
191     PrintStatisticsJSON(*OutStream);
192   else
193     PrintStatistics(*OutStream);
194 
195 #else
196   // Check if the -stats option is set instead of checking
197   // !Stats.Stats.empty().  In release builds, Statistics operators
198   // do nothing, so stats are never Registered.
199   if (Stats) {
200     // Get the stream to write to.
201     std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
202     (*OutStream) << "Statistics are disabled.  "
203                  << "Build with asserts or with -DLLVM_ENABLE_STATS\n";
204   }
205 #endif
206 }
207