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 static bool PrintOnExit;
49 
50 namespace {
51 /// StatisticInfo - This class is used in a ManagedStatic so that it is created
52 /// on demand (when the first statistic is bumped) and destroyed only when
53 /// llvm_shutdown is called.  We print statistics from the destructor.
54 class StatisticInfo {
55   std::vector<const Statistic*> Stats;
56   friend void llvm::PrintStatistics();
57   friend void llvm::PrintStatistics(raw_ostream &OS);
58   friend void llvm::PrintStatisticsJSON(raw_ostream &OS);
59 
60   /// Sort statistics by debugtype,name,description.
61   void sort();
62 public:
63   ~StatisticInfo();
64 
65   void addStatistic(const Statistic *S) {
66     Stats.push_back(S);
67   }
68 };
69 }
70 
71 static ManagedStatic<StatisticInfo> StatInfo;
72 static ManagedStatic<sys::SmartMutex<true> > StatLock;
73 
74 /// RegisterStatistic - The first time a statistic is bumped, this method is
75 /// called.
76 void Statistic::RegisterStatistic() {
77   // If stats are enabled, inform StatInfo that this statistic should be
78   // printed.
79   sys::SmartScopedLock<true> Writer(*StatLock);
80   if (!Initialized) {
81     if (Stats || Enabled)
82       StatInfo->addStatistic(this);
83 
84     TsanHappensBefore(this);
85     sys::MemoryFence();
86     // Remember we have been registered.
87     TsanIgnoreWritesBegin();
88     Initialized = true;
89     TsanIgnoreWritesEnd();
90   }
91 }
92 
93 // Print information when destroyed, iff command line option is specified.
94 StatisticInfo::~StatisticInfo() {
95   if (::Stats || PrintOnExit)
96     llvm::PrintStatistics();
97 }
98 
99 void llvm::EnableStatistics(bool PrintOnExit) {
100   Enabled = true;
101   ::PrintOnExit = PrintOnExit;
102 }
103 
104 bool llvm::AreStatisticsEnabled() {
105   return Enabled || Stats;
106 }
107 
108 void StatisticInfo::sort() {
109   std::stable_sort(Stats.begin(), Stats.end(),
110                    [](const Statistic *LHS, const Statistic *RHS) {
111     if (int Cmp = std::strcmp(LHS->getDebugType(), RHS->getDebugType()))
112       return Cmp < 0;
113 
114     if (int Cmp = std::strcmp(LHS->getName(), RHS->getName()))
115       return Cmp < 0;
116 
117     return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
118   });
119 }
120 
121 void llvm::PrintStatistics(raw_ostream &OS) {
122   StatisticInfo &Stats = *StatInfo;
123 
124   // Figure out how long the biggest Value and Name fields are.
125   unsigned MaxDebugTypeLen = 0, MaxValLen = 0;
126   for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
127     MaxValLen = std::max(MaxValLen,
128                          (unsigned)utostr(Stats.Stats[i]->getValue()).size());
129     MaxDebugTypeLen = std::max(MaxDebugTypeLen,
130                          (unsigned)std::strlen(Stats.Stats[i]->getDebugType()));
131   }
132 
133   Stats.sort();
134 
135   // Print out the statistics header...
136   OS << "===" << std::string(73, '-') << "===\n"
137      << "                          ... Statistics Collected ...\n"
138      << "===" << std::string(73, '-') << "===\n\n";
139 
140   // Print all of the statistics.
141   for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i)
142     OS << format("%*u %-*s - %s\n",
143                  MaxValLen, Stats.Stats[i]->getValue(),
144                  MaxDebugTypeLen, Stats.Stats[i]->getDebugType(),
145                  Stats.Stats[i]->getDesc());
146 
147   OS << '\n';  // Flush the output stream.
148   OS.flush();
149 }
150 
151 static void write_json_string_escaped(raw_ostream &OS, const char *string) {
152   // Out current usage should not need any escaping. Keep it simple and just
153   // check that the input is pure ASCII without special characers.
154 #ifndef NDEBUG
155   for (const unsigned char *c = (const unsigned char*)string; *c != '\0'; ++c) {
156     assert(*c != '\\' && *c != '\"' && *c >= 0x20 && *c < 0x80);
157   }
158 #endif
159   OS << string;
160 }
161 
162 void llvm::PrintStatisticsJSON(raw_ostream &OS) {
163   StatisticInfo &Stats = *StatInfo;
164 
165   Stats.sort();
166 
167   // Print all of the statistics.
168   OS << "{\n";
169   const char *delim = "";
170   for (const Statistic *Stat : Stats.Stats) {
171     OS << delim;
172     OS << "\t\"";
173     write_json_string_escaped(OS, Stat->getDebugType());
174     OS << '.';
175     write_json_string_escaped(OS, Stat->getName());
176     OS << "\": " << Stat->getValue();
177     delim = ",\n";
178   }
179   OS << "\n}\n";
180   OS.flush();
181 }
182 
183 void llvm::PrintStatistics() {
184 #if !defined(NDEBUG) || defined(LLVM_ENABLE_STATS)
185   StatisticInfo &Stats = *StatInfo;
186 
187   // Statistics not enabled?
188   if (Stats.Stats.empty()) return;
189 
190   // Get the stream to write to.
191   std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
192   if (StatsAsJSON)
193     PrintStatisticsJSON(*OutStream);
194   else
195     PrintStatistics(*OutStream);
196 
197 #else
198   // Check if the -stats option is set instead of checking
199   // !Stats.Stats.empty().  In release builds, Statistics operators
200   // do nothing, so stats are never Registered.
201   if (Stats) {
202     // Get the stream to write to.
203     std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
204     (*OutStream) << "Statistics are disabled.  "
205                  << "Build with asserts or with -DLLVM_ENABLE_STATS\n";
206   }
207 #endif
208 }
209