269 lines · cpp
1//===-- Statistic.cpp - Easy way to expose stats information --------------===//2//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-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements the 'Statistic' class, which is designed to be an easy10// way to expose various success metrics from passes. These statistics are11// printed at the end of a run, when the -stats command line option is enabled12// on the command line.13//14// This is useful for reporting information like the number of instructions15// simplified, optimized or removed by various transformations, like this:16//17// static Statistic NumInstEliminated("GCSE", "Number of instructions killed");18//19// Later, in the code: ++NumInstEliminated;20//21//===----------------------------------------------------------------------===//22 23#include "llvm/ADT/Statistic.h"24 25#include "DebugOptions.h"26 27#include "llvm/ADT/StringExtras.h"28#include "llvm/Support/CommandLine.h"29#include "llvm/Support/Compiler.h"30#include "llvm/Support/Debug.h"31#include "llvm/Support/Format.h"32#include "llvm/Support/ManagedStatic.h"33#include "llvm/Support/Mutex.h"34#include "llvm/Support/Timer.h"35#include "llvm/Support/YAMLTraits.h"36#include "llvm/Support/raw_ostream.h"37#include <algorithm>38#include <cstring>39using namespace llvm;40 41/// -stats - Command line option to cause transformations to emit stats about42/// what they did.43///44static bool EnableStats;45static bool StatsAsJSON;46static bool Enabled;47static bool PrintOnExit;48 49void llvm::initStatisticOptions() {50 static cl::opt<bool, true> registerEnableStats{51 "stats",52 cl::desc(53 "Enable statistics output from program (available with Asserts)"),54 cl::location(EnableStats), cl::Hidden};55 static cl::opt<bool, true> registerStatsAsJson{56 "stats-json", cl::desc("Display statistics as json data"),57 cl::location(StatsAsJSON), cl::Hidden};58}59 60namespace {61/// This class is used in a ManagedStatic so that it is created on demand (when62/// the first statistic is bumped) and destroyed only when llvm_shutdown is63/// called. We print statistics from the destructor.64/// This class is also used to look up statistic values from applications that65/// use LLVM.66class StatisticInfo {67 std::vector<TrackingStatistic *> Stats;68 69 friend void llvm::PrintStatistics();70 friend void llvm::PrintStatistics(raw_ostream &OS);71 friend void llvm::PrintStatisticsJSON(raw_ostream &OS);72 73 /// Sort statistics by debugtype,name,description.74 void sort();75public:76 using const_iterator = std::vector<TrackingStatistic *>::const_iterator;77 78 StatisticInfo();79 ~StatisticInfo();80 81 void addStatistic(TrackingStatistic *S) { Stats.push_back(S); }82 83 const_iterator begin() const { return Stats.begin(); }84 const_iterator end() const { return Stats.end(); }85 iterator_range<const_iterator> statistics() const {86 return {begin(), end()};87 }88 89 void reset();90};91} // end anonymous namespace92 93static ManagedStatic<StatisticInfo> StatInfo;94static ManagedStatic<sys::SmartMutex<true> > StatLock;95 96/// RegisterStatistic - The first time a statistic is bumped, this method is97/// called.98void TrackingStatistic::RegisterStatistic() {99 // If stats are enabled, inform StatInfo that this statistic should be100 // printed.101 // llvm_shutdown calls destructors while holding the ManagedStatic mutex.102 // These destructors end up calling PrintStatistics, which takes StatLock.103 // Since dereferencing StatInfo and StatLock can require taking the104 // ManagedStatic mutex, doing so with StatLock held would lead to a lock105 // order inversion. To avoid that, we dereference the ManagedStatics first,106 // and only take StatLock afterwards.107 if (!Initialized.load(std::memory_order_relaxed)) {108 sys::SmartMutex<true> &Lock = *StatLock;109 StatisticInfo &SI = *StatInfo;110 sys::SmartScopedLock<true> Writer(Lock);111 // Check Initialized again after acquiring the lock.112 if (Initialized.load(std::memory_order_relaxed))113 return;114 if (EnableStats || Enabled)115 SI.addStatistic(this);116 117 // Remember we have been registered.118 Initialized.store(true, std::memory_order_release);119 }120}121 122StatisticInfo::StatisticInfo() {123 // Ensure that necessary timer global objects are created first so they are124 // destructed after us.125 TimerGroup::constructForStatistics();126}127 128// Print information when destroyed, iff command line option is specified.129StatisticInfo::~StatisticInfo() {130 if (EnableStats || PrintOnExit)131 llvm::PrintStatistics();132}133 134void llvm::EnableStatistics(bool DoPrintOnExit) {135 Enabled = true;136 PrintOnExit = DoPrintOnExit;137}138 139bool llvm::AreStatisticsEnabled() { return Enabled || EnableStats; }140 141void StatisticInfo::sort() {142 llvm::stable_sort(143 Stats, [](const TrackingStatistic *LHS, const TrackingStatistic *RHS) {144 if (int Cmp = std::strcmp(LHS->getDebugType(), RHS->getDebugType()))145 return Cmp < 0;146 147 if (int Cmp = std::strcmp(LHS->getName(), RHS->getName()))148 return Cmp < 0;149 150 return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;151 });152}153 154void StatisticInfo::reset() {155 sys::SmartScopedLock<true> Writer(*StatLock);156 157 // Tell each statistic that it isn't registered so it has to register158 // again. We're holding the lock so it won't be able to do so until we're159 // finished. Once we've forced it to re-register (after we return), then zero160 // the value.161 for (auto *Stat : Stats) {162 // Value updates to a statistic that complete before this statement in the163 // iteration for that statistic will be lost as intended.164 Stat->Initialized = false;165 Stat->Value = 0;166 }167 168 // Clear the registration list and release the lock once we're done. Any169 // pending updates from other threads will safely take effect after we return.170 // That might not be what the user wants if they're measuring a compilation171 // but it's their responsibility to prevent concurrent compilations to make172 // a single compilation measurable.173 Stats.clear();174}175 176void llvm::PrintStatistics(raw_ostream &OS) {177 StatisticInfo &Stats = *StatInfo;178 179 // Figure out how long the biggest Value and Name fields are.180 unsigned MaxDebugTypeLen = 0, MaxValLen = 0;181 for (TrackingStatistic *Stat : Stats.Stats) {182 MaxValLen = std::max(MaxValLen, (unsigned)utostr(Stat->getValue()).size());183 MaxDebugTypeLen =184 std::max(MaxDebugTypeLen, (unsigned)std::strlen(Stat->getDebugType()));185 }186 187 Stats.sort();188 189 // Print out the statistics header...190 OS << "===" << std::string(73, '-') << "===\n"191 << " ... Statistics Collected ...\n"192 << "===" << std::string(73, '-') << "===\n\n";193 194 // Print all of the statistics.195 for (TrackingStatistic *Stat : Stats.Stats)196 OS << format("%*" PRIu64 " %-*s - %s\n", MaxValLen, Stat->getValue(),197 MaxDebugTypeLen, Stat->getDebugType(), Stat->getDesc());198 199 OS << '\n'; // Flush the output stream.200 OS.flush();201}202 203void llvm::PrintStatisticsJSON(raw_ostream &OS) {204 sys::SmartScopedLock<true> Reader(*StatLock);205 StatisticInfo &Stats = *StatInfo;206 207 Stats.sort();208 209 // Print all of the statistics.210 OS << "{\n";211 const char *delim = "";212 for (const TrackingStatistic *Stat : Stats.Stats) {213 OS << delim;214 assert(yaml::needsQuotes(Stat->getDebugType()) == yaml::QuotingType::None &&215 "Statistic group/type name is simple.");216 assert(yaml::needsQuotes(Stat->getName()) == yaml::QuotingType::None &&217 "Statistic name is simple");218 OS << "\t\"" << Stat->getDebugType() << '.' << Stat->getName() << "\": "219 << Stat->getValue();220 delim = ",\n";221 }222 // Print timers.223 TimerGroup::printAllJSONValues(OS, delim);224 225 OS << "\n}\n";226 OS.flush();227}228 229void llvm::PrintStatistics() {230#if LLVM_ENABLE_STATS231 sys::SmartScopedLock<true> Reader(*StatLock);232 StatisticInfo &Stats = *StatInfo;233 234 // Statistics not enabled?235 if (Stats.Stats.empty()) return;236 237 // Get the stream to write to.238 std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();239 if (StatsAsJSON)240 PrintStatisticsJSON(*OutStream);241 else242 PrintStatistics(*OutStream);243 244#else245 // Check if the -stats option is set instead of checking246 // !Stats.Stats.empty(). In release builds, Statistics operators247 // do nothing, so stats are never Registered.248 if (EnableStats) {249 // Get the stream to write to.250 std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();251 (*OutStream) << "Statistics are disabled. "252 << "Build with asserts or with -DLLVM_FORCE_ENABLE_STATS\n";253 }254#endif255}256 257std::vector<std::pair<StringRef, uint64_t>> llvm::GetStatistics() {258 sys::SmartScopedLock<true> Reader(*StatLock);259 std::vector<std::pair<StringRef, uint64_t>> ReturnStats;260 261 for (const auto &Stat : StatInfo->statistics())262 ReturnStats.emplace_back(Stat->getName(), Stat->getValue());263 return ReturnStats;264}265 266void llvm::ResetStatistics() {267 StatInfo->reset();268}269