path: root/contrib/libs/llvm12/lib/Support/Statistic.cpp

//===-- Statistic.cpp - Easy way to expose stats information --------------===// 
// 
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 
// See https://llvm.org/LICENSE.txt for license information. 
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 
// 
//===----------------------------------------------------------------------===// 
// 
// 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> EnableStats( 
    "stats", 
    cl::desc("Enable statistics output from program (available with Asserts)"), 
    cl::Hidden); 
 
static cl::opt<bool> StatsAsJSON("stats-json", 
                                 cl::desc("Display statistics as json data"), 
                                 cl::Hidden); 
 
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<TrackingStatistic *> 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(); 
public: 
  using const_iterator = std::vector<TrackingStatistic *>::const_iterator; 
 
  StatisticInfo(); 
  ~StatisticInfo(); 
 
  void addStatistic(TrackingStatistic *S) { Stats.push_back(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 TrackingStatistic::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)) 
      return; 
    if (EnableStats || Enabled) 
      SI.addStatistic(this); 
 
    // Remember we have been registered. 
    Initialized.store(true, std::memory_order_release); 
  } 
} 
 
StatisticInfo::StatisticInfo() { 
  // Ensure timergroup lists are created first so they are destructed after us. 
  TimerGroup::ConstructTimerLists(); 
} 
 
// Print information when destroyed, iff command line option is specified. 
StatisticInfo::~StatisticInfo() { 
  if (EnableStats || PrintOnExit) 
    llvm::PrintStatistics(); 
} 
 
void llvm::EnableStatistics(bool DoPrintOnExit) { 
  Enabled = true; 
  PrintOnExit = DoPrintOnExit; 
} 
 
bool llvm::AreStatisticsEnabled() { 
  return Enabled || EnableStats; 
} 
 
void StatisticInfo::sort() { 
  llvm::stable_sort( 
      Stats, [](const TrackingStatistic *LHS, const TrackingStatistic *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. 
  Stats.clear(); 
} 
 
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, 
                         (unsigned)utostr(Stats.Stats[i]->getValue()).size()); 
    MaxDebugTypeLen = std::max(MaxDebugTypeLen, 
                         (unsigned)std::strlen(Stats.Stats[i]->getDebugType())); 
  } 
 
  Stats.sort(); 
 
  // 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(), 
                 Stats.Stats[i]->getDesc()); 
 
  OS << '\n';  // Flush the output stream. 
  OS.flush(); 
} 
 
void llvm::PrintStatisticsJSON(raw_ostream &OS) { 
  sys::SmartScopedLock<true> Reader(*StatLock); 
  StatisticInfo &Stats = *StatInfo; 
 
  Stats.sort(); 
 
  // Print all of the statistics. 
  OS << "{\n"; 
  const char *delim = ""; 
  for (const TrackingStatistic *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"; 
  OS.flush(); 
} 
 
void llvm::PrintStatistics() { 
#if LLVM_ENABLE_STATS 
  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) 
    PrintStatisticsJSON(*OutStream); 
  else 
    PrintStatistics(*OutStream); 
 
#else 
  // 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 (EnableStats) { 
    // Get the stream to write to. 
    std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile(); 
    (*OutStream) << "Statistics are disabled.  " 
                 << "Build with asserts or with -DLLVM_FORCE_ENABLE_STATS\n"; 
  } 
#endif 
} 
 
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() { 
  StatInfo->reset(); 
}