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//===-- Statistic.cpp - Easy way to expose stats information --------------===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file implements the 'Statistic' class, which is designed to be an easy
// way to expose various success metrics from passes. These statistics are
// printed at the end of a run, when the -stats command line option is enabled
// on the command line.
// This is useful for reporting information like the number of instructions
// simplified, optimized or removed by various transformations, like this:
// static Statistic NumInstEliminated("GCSE", "Number of instructions killed");
// Later, in the code: ++NumInstEliminated;
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Mutex.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/YAMLTraits.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cstring>
using namespace llvm;
/// -stats - Command line option to cause transformations to emit stats about
/// what they did.
static cl::opt<bool> Stats(
cl::desc("Enable statistics output from program (available with Asserts)"),
static cl::opt<bool> StatsAsJSON("stats-json",
cl::desc("Display statistics as json data"),
static bool Enabled;
static bool PrintOnExit;
namespace {
/// This class is used in a ManagedStatic so that it is created on demand (when
/// the first statistic is bumped) and destroyed only when llvm_shutdown is
/// called. We print statistics from the destructor.
/// This class is also used to look up statistic values from applications that
/// use LLVM.
class StatisticInfo {
std::vector<Statistic*> Stats;
friend void llvm::PrintStatistics();
friend void llvm::PrintStatistics(raw_ostream &OS);
friend void llvm::PrintStatisticsJSON(raw_ostream &OS);
/// Sort statistics by debugtype,name,description.
void sort();
using const_iterator = std::vector<Statistic *>::const_iterator;
void addStatistic(Statistic *S) {
const_iterator begin() const { return Stats.begin(); }
const_iterator end() const { return Stats.end(); }
iterator_range<const_iterator> statistics() const {
return {begin(), end()};
void reset();
} // end anonymous namespace
static ManagedStatic<StatisticInfo> StatInfo;
static ManagedStatic<sys::SmartMutex<true> > StatLock;
/// RegisterStatistic - The first time a statistic is bumped, this method is
/// called.
void Statistic::RegisterStatistic() {
// If stats are enabled, inform StatInfo that this statistic should be
// printed.
// llvm_shutdown calls destructors while holding the ManagedStatic mutex.
// These destructors end up calling PrintStatistics, which takes StatLock.
// Since dereferencing StatInfo and StatLock can require taking the
// ManagedStatic mutex, doing so with StatLock held would lead to a lock
// order inversion. To avoid that, we dereference the ManagedStatics first,
// and only take StatLock afterwards.
if (!Initialized.load(std::memory_order_relaxed)) {
sys::SmartMutex<true> &Lock = *StatLock;
StatisticInfo &SI = *StatInfo;
sys::SmartScopedLock<true> Writer(Lock);
// Check Initialized again after acquiring the lock.
if (Initialized.load(std::memory_order_relaxed))
if (Stats || Enabled)
// Remember we have been registered., std::memory_order_release);
StatisticInfo::StatisticInfo() {
// Ensure timergroup lists are created first so they are destructed after us.
// Print information when destroyed, iff command line option is specified.
StatisticInfo::~StatisticInfo() {
if (::Stats || PrintOnExit)
void llvm::EnableStatistics(bool PrintOnExit) {
Enabled = true;
::PrintOnExit = PrintOnExit;
bool llvm::AreStatisticsEnabled() {
return Enabled || Stats;
void StatisticInfo::sort() {
std::stable_sort(Stats.begin(), Stats.end(),
[](const Statistic *LHS, const Statistic *RHS) {
if (int Cmp = std::strcmp(LHS->getDebugType(), RHS->getDebugType()))
return Cmp < 0;
if (int Cmp = std::strcmp(LHS->getName(), RHS->getName()))
return Cmp < 0;
return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
void StatisticInfo::reset() {
sys::SmartScopedLock<true> Writer(*StatLock);
// Tell each statistic that it isn't registered so it has to register
// again. We're holding the lock so it won't be able to do so until we're
// finished. Once we've forced it to re-register (after we return), then zero
// the value.
for (auto *Stat : Stats) {
// Value updates to a statistic that complete before this statement in the
// iteration for that statistic will be lost as intended.
Stat->Initialized = false;
Stat->Value = 0;
// Clear the registration list and release the lock once we're done. Any
// pending updates from other threads will safely take effect after we return.
// That might not be what the user wants if they're measuring a compilation
// but it's their responsibility to prevent concurrent compilations to make
// a single compilation measurable.
void llvm::PrintStatistics(raw_ostream &OS) {
StatisticInfo &Stats = *StatInfo;
// Figure out how long the biggest Value and Name fields are.
unsigned MaxDebugTypeLen = 0, MaxValLen = 0;
for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
MaxValLen = std::max(MaxValLen,
MaxDebugTypeLen = std::max(MaxDebugTypeLen,
// Print out the statistics header...
OS << "===" << std::string(73, '-') << "===\n"
<< " ... Statistics Collected ...\n"
<< "===" << std::string(73, '-') << "===\n\n";
// Print all of the statistics.
for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i)
OS << format("%*u %-*s - %s\n",
MaxValLen, Stats.Stats[i]->getValue(),
MaxDebugTypeLen, Stats.Stats[i]->getDebugType(),
OS << '\n'; // Flush the output stream.
void llvm::PrintStatisticsJSON(raw_ostream &OS) {
sys::SmartScopedLock<true> Reader(*StatLock);
StatisticInfo &Stats = *StatInfo;
// Print all of the statistics.
OS << "{\n";
const char *delim = "";
for (const Statistic *Stat : Stats.Stats) {
OS << delim;
assert(yaml::needsQuotes(Stat->getDebugType()) == yaml::QuotingType::None &&
"Statistic group/type name is simple.");
assert(yaml::needsQuotes(Stat->getName()) == yaml::QuotingType::None &&
"Statistic name is simple");
OS << "\t\"" << Stat->getDebugType() << '.' << Stat->getName() << "\": "
<< Stat->getValue();
delim = ",\n";
// Print timers.
TimerGroup::printAllJSONValues(OS, delim);
OS << "\n}\n";
void llvm::PrintStatistics() {
sys::SmartScopedLock<true> Reader(*StatLock);
StatisticInfo &Stats = *StatInfo;
// Statistics not enabled?
if (Stats.Stats.empty()) return;
// Get the stream to write to.
std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
if (StatsAsJSON)
// Check if the -stats option is set instead of checking
// !Stats.Stats.empty(). In release builds, Statistics operators
// do nothing, so stats are never Registered.
if (Stats) {
// Get the stream to write to.
std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
(*OutStream) << "Statistics are disabled. "
<< "Build with asserts or with -DLLVM_ENABLE_STATS\n";
const std::vector<std::pair<StringRef, unsigned>> llvm::GetStatistics() {
sys::SmartScopedLock<true> Reader(*StatLock);
std::vector<std::pair<StringRef, unsigned>> ReturnStats;
for (const auto &Stat : StatInfo->statistics())
ReturnStats.emplace_back(Stat->getName(), Stat->getValue());
return ReturnStats;
void llvm::ResetStatistics() {