LLVM  9.0.0svn
Statistic.cpp
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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-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
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.
13 //
14 // This is useful for reporting information like the number of instructions
15 // 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 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/Support/Compiler.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Support/Format.h"
30 #include "llvm/Support/Mutex.h"
31 #include "llvm/Support/Timer.h"
34 #include <algorithm>
35 #include <cstring>
36 using namespace llvm;
37 
38 /// -stats - Command line option to cause transformations to emit stats about
39 /// what they did.
40 ///
41 static cl::opt<bool> Stats(
42  "stats",
43  cl::desc("Enable statistics output from program (available with Asserts)"),
44  cl::Hidden);
45 
46 static cl::opt<bool> StatsAsJSON("stats-json",
47  cl::desc("Display statistics as json data"),
48  cl::Hidden);
49 
50 static bool Enabled;
51 static bool PrintOnExit;
52 
53 namespace {
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
58 /// use LLVM.
59 class StatisticInfo {
60  std::vector<Statistic*> Stats;
61 
62  friend void llvm::PrintStatistics();
63  friend void llvm::PrintStatistics(raw_ostream &OS);
64  friend void llvm::PrintStatisticsJSON(raw_ostream &OS);
65 
66  /// Sort statistics by debugtype,name,description.
67  void sort();
68 public:
69  using const_iterator = std::vector<Statistic *>::const_iterator;
70 
71  StatisticInfo();
72  ~StatisticInfo();
73 
74  void addStatistic(Statistic *S) {
75  Stats.push_back(S);
76  }
77 
78  const_iterator begin() const { return Stats.begin(); }
79  const_iterator end() const { return Stats.end(); }
80  iterator_range<const_iterator> statistics() const {
81  return {begin(), end()};
82  }
83 
84  void reset();
85 };
86 } // end anonymous namespace
87 
90 
91 /// RegisterStatistic - The first time a statistic is bumped, this method is
92 /// called.
94  // If stats are enabled, inform StatInfo that this statistic should be
95  // printed.
96  // llvm_shutdown calls destructors while holding the ManagedStatic mutex.
97  // These destructors end up calling PrintStatistics, which takes StatLock.
98  // Since dereferencing StatInfo and StatLock can require taking the
99  // ManagedStatic mutex, doing so with StatLock held would lead to a lock
100  // order inversion. To avoid that, we dereference the ManagedStatics first,
101  // and only take StatLock afterwards.
102  if (!Initialized.load(std::memory_order_relaxed)) {
104  StatisticInfo &SI = *StatInfo;
105  sys::SmartScopedLock<true> Writer(Lock);
106  // Check Initialized again after acquiring the lock.
107  if (Initialized.load(std::memory_order_relaxed))
108  return;
109  if (Stats || Enabled)
110  SI.addStatistic(this);
111 
112  // Remember we have been registered.
113  Initialized.store(true, std::memory_order_release);
114  }
115 }
116 
117 StatisticInfo::StatisticInfo() {
118  // Ensure timergroup lists are created first so they are destructed after us.
120 }
121 
122 // Print information when destroyed, iff command line option is specified.
123 StatisticInfo::~StatisticInfo() {
124  if (::Stats || PrintOnExit)
126 }
127 
128 void llvm::EnableStatistics(bool PrintOnExit) {
129  Enabled = true;
131 }
132 
134  return Enabled || Stats;
135 }
136 
137 void StatisticInfo::sort() {
138  llvm::stable_sort(Stats, [](const Statistic *LHS, const Statistic *RHS) {
139  if (int Cmp = std::strcmp(LHS->getDebugType(), RHS->getDebugType()))
140  return Cmp < 0;
141 
142  if (int Cmp = std::strcmp(LHS->getName(), RHS->getName()))
143  return Cmp < 0;
144 
145  return std::strcmp(LHS->getDesc(), RHS->getDesc()) < 0;
146  });
147 }
148 
149 void StatisticInfo::reset() {
150  sys::SmartScopedLock<true> Writer(*StatLock);
151 
152  // Tell each statistic that it isn't registered so it has to register
153  // again. We're holding the lock so it won't be able to do so until we're
154  // finished. Once we've forced it to re-register (after we return), then zero
155  // the value.
156  for (auto *Stat : Stats) {
157  // Value updates to a statistic that complete before this statement in the
158  // iteration for that statistic will be lost as intended.
159  Stat->Initialized = false;
160  Stat->Value = 0;
161  }
162 
163  // Clear the registration list and release the lock once we're done. Any
164  // pending updates from other threads will safely take effect after we return.
165  // That might not be what the user wants if they're measuring a compilation
166  // but it's their responsibility to prevent concurrent compilations to make
167  // a single compilation measurable.
168  Stats.clear();
169 }
170 
172  StatisticInfo &Stats = *StatInfo;
173 
174  // Figure out how long the biggest Value and Name fields are.
175  unsigned MaxDebugTypeLen = 0, MaxValLen = 0;
176  for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i) {
177  MaxValLen = std::max(MaxValLen,
178  (unsigned)utostr(Stats.Stats[i]->getValue()).size());
179  MaxDebugTypeLen = std::max(MaxDebugTypeLen,
180  (unsigned)std::strlen(Stats.Stats[i]->getDebugType()));
181  }
182 
183  Stats.sort();
184 
185  // Print out the statistics header...
186  OS << "===" << std::string(73, '-') << "===\n"
187  << " ... Statistics Collected ...\n"
188  << "===" << std::string(73, '-') << "===\n\n";
189 
190  // Print all of the statistics.
191  for (size_t i = 0, e = Stats.Stats.size(); i != e; ++i)
192  OS << format("%*u %-*s - %s\n",
193  MaxValLen, Stats.Stats[i]->getValue(),
194  MaxDebugTypeLen, Stats.Stats[i]->getDebugType(),
195  Stats.Stats[i]->getDesc());
196 
197  OS << '\n'; // Flush the output stream.
198  OS.flush();
199 }
200 
202  sys::SmartScopedLock<true> Reader(*StatLock);
203  StatisticInfo &Stats = *StatInfo;
204 
205  Stats.sort();
206 
207  // Print all of the statistics.
208  OS << "{\n";
209  const char *delim = "";
210  for (const Statistic *Stat : Stats.Stats) {
211  OS << delim;
212  assert(yaml::needsQuotes(Stat->getDebugType()) == yaml::QuotingType::None &&
213  "Statistic group/type name is simple.");
214  assert(yaml::needsQuotes(Stat->getName()) == yaml::QuotingType::None &&
215  "Statistic name is simple");
216  OS << "\t\"" << Stat->getDebugType() << '.' << Stat->getName() << "\": "
217  << Stat->getValue();
218  delim = ",\n";
219  }
220  // Print timers.
222 
223  OS << "\n}\n";
224  OS.flush();
225 }
226 
228 #if LLVM_ENABLE_STATS
229  sys::SmartScopedLock<true> Reader(*StatLock);
230  StatisticInfo &Stats = *StatInfo;
231 
232  // Statistics not enabled?
233  if (Stats.Stats.empty()) return;
234 
235  // Get the stream to write to.
236  std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
237  if (StatsAsJSON)
238  PrintStatisticsJSON(*OutStream);
239  else
240  PrintStatistics(*OutStream);
241 
242 #else
243  // Check if the -stats option is set instead of checking
244  // !Stats.Stats.empty(). In release builds, Statistics operators
245  // do nothing, so stats are never Registered.
246  if (Stats) {
247  // Get the stream to write to.
248  std::unique_ptr<raw_ostream> OutStream = CreateInfoOutputFile();
249  (*OutStream) << "Statistics are disabled. "
250  << "Build with asserts or with -DLLVM_ENABLE_STATS\n";
251  }
252 #endif
253 }
254 
255 const std::vector<std::pair<StringRef, unsigned>> llvm::GetStatistics() {
256  sys::SmartScopedLock<true> Reader(*StatLock);
257  std::vector<std::pair<StringRef, unsigned>> ReturnStats;
258 
259  for (const auto &Stat : StatInfo->statistics())
260  ReturnStats.emplace_back(Stat->getName(), Stat->getValue());
261  return ReturnStats;
262 }
263 
265  StatInfo->reset();
266 }
const NoneType None
Definition: None.h:23
static bool PrintOnExit
Definition: Statistic.cpp:51
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:233
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
void EnableStatistics(bool PrintOnExit=true)
Enable the collection and printing of statistics.
Definition: Statistic.cpp:128
const_iterator begin(StringRef path, Style style=Style::native)
Get begin iterator over path.
Definition: Path.cpp:224
This class represents lattice values for constants.
Definition: AllocatorList.h:23
format_object< Ts... > format(const char *Fmt, const Ts &... Vals)
These are helper functions used to produce formatted output.
Definition: Format.h:123
SmartMutex - A mutex with a compile time constant parameter that indicates whether this mutex should ...
Definition: Mutex.h:91
static sys::Mutex Lock
void RegisterStatistic()
RegisterStatistic - The first time a statistic is bumped, this method is called.
Definition: Statistic.cpp:93
void ResetStatistics()
Reset the statistics.
Definition: Statistic.cpp:264
const char * getDebugType() const
Definition: Statistic.h:56
friend const_iterator begin(StringRef path, Style style)
Get begin iterator over path.
Definition: Path.cpp:224
static ManagedStatic< StatisticInfo > StatInfo
Definition: Statistic.cpp:88
std::unique_ptr< raw_fd_ostream > CreateInfoOutputFile()
Return a file stream to print our output on.
Definition: Timer.cpp:58
friend const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:233
const std::vector< std::pair< StringRef, unsigned > > GetStatistics()
Get the statistics.
Definition: Statistic.cpp:255
void sort(IteratorTy Start, IteratorTy End)
Definition: STLExtras.h:1115
void PrintStatisticsJSON(raw_ostream &OS)
Print statistics in JSON format.
Definition: Statistic.cpp:201
auto size(R &&Range, typename std::enable_if< std::is_same< typename std::iterator_traits< decltype(Range.begin())>::iterator_category, std::random_access_iterator_tag >::value, void >::type *=nullptr) -> decltype(std::distance(Range.begin(), Range.end()))
Get the size of a range.
Definition: STLExtras.h:1166
unsigned getValue() const
Definition: Statistic.h:55
const char * getDesc() const
Definition: Statistic.h:58
std::string utostr(uint64_t X, bool isNeg=false)
Definition: StringExtras.h:223
static bool Enabled
Definition: Statistic.cpp:50
A range adaptor for a pair of iterators.
static const char * printAllJSONValues(raw_ostream &OS, const char *delim)
Prints all timers as JSON key/value pairs.
Definition: Timer.cpp:433
const char * getName() const
Definition: Statistic.h:57
void PrintStatistics()
Print statistics to the file returned by CreateInfoOutputFile().
Definition: Statistic.cpp:227
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
void stable_sort(R &&Range)
Definition: STLExtras.h:1309
static void ConstructTimerLists()
Ensure global timer group lists are initialized.
Definition: Timer.cpp:440
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:45
static cl::opt< bool > Stats("stats", cl::desc("Enable statistics output from program (available with Asserts)"), cl::Hidden)
-stats - Command line option to cause transformations to emit stats about what they did...
ManagedStatic - This transparently changes the behavior of global statics to be lazily constructed on...
Definition: ManagedStatic.h:83
static ManagedStatic< sys::SmartMutex< true > > StatLock
Definition: Statistic.cpp:89
bool AreStatisticsEnabled()
Check if statistics are enabled.
Definition: Statistic.cpp:133
static cl::opt< bool > StatsAsJSON("stats-json", cl::desc("Display statistics as json data"), cl::Hidden)