1 //===-- Statistic.cpp - Easy way to expose stats information --------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file implements the 'Statistic' class, which is designed to be an easy
10 // way to expose various success metrics from passes. These statistics are
11 // printed at the end of a run, when the -stats command line option is enabled
12 // on the command line.
14 // This is useful for reporting information like the number of instructions
15 // simplified, optimized or removed by various transformations, like this:
17 // static Statistic NumInstEliminated("GCSE", "Number of instructions killed");
19 // Later, in the code: ++NumInstEliminated;
21 //===----------------------------------------------------------------------===//
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/ADT/StringExtras.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Support/Compiler.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Support/Format.h"
29 #include "llvm/Support/ManagedStatic.h"
30 #include "llvm/Support/Mutex.h"
31 #include "llvm/Support/Timer.h"
32 #include "llvm/Support/YAMLTraits.h"
33 #include "llvm/Support/raw_ostream.h"
38 /// -stats - Command line option to cause transformations to emit stats about
41 static cl::opt<bool> EnableStats(
43 cl::desc("Enable statistics output from program (available with Asserts)"),
46 static cl::opt<bool> StatsAsJSON("stats-json",
47 cl::desc("Display statistics as json data"),
51 static bool PrintOnExit;
54 /// This class is used in a ManagedStatic so that it is created on demand (when
55 /// the first statistic is bumped) and destroyed only when llvm_shutdown is
56 /// called. We print statistics from the destructor.
57 /// This class is also used to look up statistic values from applications that
60 std::vector<TrackingStatistic *> Stats;
62 friend void llvm::PrintStatistics();
63 friend void llvm::PrintStatistics(raw_ostream &OS);
64 friend void llvm::PrintStatisticsJSON(raw_ostream &OS);
66 /// Sort statistics by debugtype,name,description.
69 using const_iterator = std::vector<TrackingStatistic *>::const_iterator;
74 void addStatistic(TrackingStatistic *S) { Stats.push_back(S); }
76 const_iterator begin() const { return Stats.begin(); }
77 const_iterator end() const { return Stats.end(); }
78 iterator_range<const_iterator> statistics() const {
79 return {begin(), end()};
84 } // end anonymous namespace
86 static ManagedStatic<StatisticInfo> StatInfo;
87 static ManagedStatic<sys::SmartMutex<true> > StatLock;
89 /// RegisterStatistic - The first time a statistic is bumped, this method is
91 void TrackingStatistic::RegisterStatistic() {
92 // If stats are enabled, inform StatInfo that this statistic should be
94 // llvm_shutdown calls destructors while holding the ManagedStatic mutex.
95 // These destructors end up calling PrintStatistics, which takes StatLock.
96 // Since dereferencing StatInfo and StatLock can require taking the
97 // ManagedStatic mutex, doing so with StatLock held would lead to a lock
98 // order inversion. To avoid that, we dereference the ManagedStatics first,
99 // and only take StatLock afterwards.
100 if (!Initialized.load(std::memory_order_relaxed)) {
101 sys::SmartMutex<true> &Lock = *StatLock;
102 StatisticInfo &SI = *StatInfo;
103 sys::SmartScopedLock<true> Writer(Lock);
104 // Check Initialized again after acquiring the lock.
105 if (Initialized.load(std::memory_order_relaxed))
107 if (EnableStats || Enabled)
108 SI.addStatistic(this);
110 // Remember we have been registered.
111 Initialized.store(true, std::memory_order_release);
115 StatisticInfo::StatisticInfo() {
116 // Ensure timergroup lists are created first so they are destructed after us.
117 TimerGroup::ConstructTimerLists();
120 // Print information when destroyed, iff command line option is specified.
121 StatisticInfo::~StatisticInfo() {
122 if (EnableStats || PrintOnExit)
123 llvm::PrintStatistics();
126 void llvm::EnableStatistics(bool DoPrintOnExit) {
128 PrintOnExit = DoPrintOnExit;
131 bool llvm::AreStatisticsEnabled() {
132 return Enabled || EnableStats;
135 void StatisticInfo::sort() {
137 Stats, [](const TrackingStatistic *LHS, const TrackingStatistic *RHS) {
138 if (int Cmp = std::strcmp(LHS->getDebugType(), RHS->getDebugType()))
141 if (int Cmp = std::strcmp(LHS->getName(), RHS->getName()))
144 return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
148 void StatisticInfo::reset() {
149 sys::SmartScopedLock<true> Writer(*StatLock);
151 // Tell each statistic that it isn't registered so it has to register
152 // again. We're holding the lock so it won't be able to do so until we're
153 // finished. Once we've forced it to re-register (after we return), then zero
155 for (auto *Stat : Stats) {
156 // Value updates to a statistic that complete before this statement in the
157 // iteration for that statistic will be lost as intended.
158 Stat->Initialized = false;
162 // Clear the registration list and release the lock once we're done. Any
163 // pending updates from other threads will safely take effect after we return.
164 // That might not be what the user wants if they're measuring a compilation
165 // but it's their responsibility to prevent concurrent compilations to make
166 // a single compilation measurable.
170 void llvm::PrintStatistics(raw_ostream &OS) {
171 StatisticInfo &Stats = *StatInfo;
173 // Figure out how long the biggest Value and Name fields are.
174 unsigned MaxDebugTypeLen = 0, MaxValLen = 0;
175 for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
176 MaxValLen = std::max(MaxValLen,
177 (unsigned)utostr(Stats.Stats[i]->getValue()).size());
178 MaxDebugTypeLen = std::max(MaxDebugTypeLen,
179 (unsigned)std::strlen(Stats.Stats[i]->getDebugType()));
184 // Print out the statistics header...
185 OS << "===" << std::string(73, '-') << "===\n"
186 << " ... Statistics Collected ...\n"
187 << "===" << std::string(73, '-') << "===\n\n";
189 // Print all of the statistics.
190 for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i)
191 OS << format("%*u %-*s - %s\n",
192 MaxValLen, Stats.Stats[i]->getValue(),
193 MaxDebugTypeLen, Stats.Stats[i]->getDebugType(),
194 Stats.Stats[i]->getDesc());
196 OS << '\n'; // Flush the output stream.
200 void llvm::PrintStatisticsJSON(raw_ostream &OS) {
201 sys::SmartScopedLock<true> Reader(*StatLock);
202 StatisticInfo &Stats = *StatInfo;
206 // Print all of the statistics.
208 const char *delim = "";
209 for (const TrackingStatistic *Stat : Stats.Stats) {
211 assert(yaml::needsQuotes(Stat->getDebugType()) == yaml::QuotingType::None &&
212 "Statistic group/type name is simple.");
213 assert(yaml::needsQuotes(Stat->getName()) == yaml::QuotingType::None &&
214 "Statistic name is simple");
215 OS << "\t\"" << Stat->getDebugType() << '.' << Stat->getName() << "\": "
220 TimerGroup::printAllJSONValues(OS, delim);
226 void llvm::PrintStatistics() {
227 #if LLVM_ENABLE_STATS
228 sys::SmartScopedLock<true> Reader(*StatLock);
229 StatisticInfo &Stats = *StatInfo;
231 // Statistics not enabled?
232 if (Stats.Stats.empty()) return;
234 // Get the stream to write to.
235 std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
237 PrintStatisticsJSON(*OutStream);
239 PrintStatistics(*OutStream);
242 // Check if the -stats option is set instead of checking
243 // !Stats.Stats.empty(). In release builds, Statistics operators
244 // do nothing, so stats are never Registered.
246 // Get the stream to write to.
247 std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
248 (*OutStream) << "Statistics are disabled. "
249 << "Build with asserts or with -DLLVM_ENABLE_STATS\n";
254 const std::vector<std::pair<StringRef, unsigned>> llvm::GetStatistics() {
255 sys::SmartScopedLock<true> Reader(*StatLock);
256 std::vector<std::pair<StringRef, unsigned>> ReturnStats;
258 for (const auto &Stat : StatInfo->statistics())
259 ReturnStats.emplace_back(Stat->getName(), Stat->getValue());
263 void llvm::ResetStatistics() {