src/llvm/include/llvm/ADT/Statistic.h

   1 //===-- llvm/ADT/Statistic.h - Easy way to expose stats ---------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines the 'Statistic' class, which is designed to be an easy way
  11 // to expose various metrics from passes.  These statistics are printed at the
  12 // end of a run (from llvm_shutdown), when the -stats command line option is
  13 // passed on the command line.
  14 //
  15 // This is useful for reporting information like the number of instructions
  16 // simplified, optimized or removed by various transformations, like this:
  17 //
  18 // static Statistic NumInstsKilled("gcse", "Number of instructions killed");
  19 //
  20 // Later, in the code: ++NumInstsKilled;
  21 //
  22 // NOTE: Statistics *must* be declared as global variables.
  23 //
  24 //===----------------------------------------------------------------------===//
  25
  26 #ifndef LLVM_ADT_STATISTIC_H
  27 #define LLVM_ADT_STATISTIC_H
  28
  29 #include "llvm/Support/Atomic.h"
  30 #include "llvm/Support/Valgrind.h"
  31
  32 namespace llvm {
  33 class raw_ostream;
  34
  35 class Statistic {
  36 public:
  37   const char *Name;
  38   const char *Desc;
  39   volatile llvm::sys::cas_flag Value;
  40   bool Initialized;
  41
  42   llvm::sys::cas_flag getValue() const { return Value; }
  43   const char *getName() const { return Name; }
  44   const char *getDesc() const { return Desc; }
  45
  46   /// construct - This should only be called for non-global statistics.
  47   void construct(const char *name, const char *desc) {
  48     Name = name; Desc = desc;
  49     Value = 0; Initialized = false;
  50   }
  51
  52   // Allow use of this class as the value itself.
  53   operator unsigned() const { return Value; }
  54
  55 #if !defined(NDEBUG) || defined(LLVM_ENABLE_STATS)
  56    const Statistic &operator=(unsigned Val) {
  57     Value = Val;
  58     return init();
  59   }
  60
  61   const Statistic &operator++() {
  62     // FIXME: This function and all those that follow carefully use an
  63     // atomic operation to update the value safely in the presence of
  64     // concurrent accesses, but not to read the return value, so the
  65     // return value is not thread safe.
  66     sys::AtomicIncrement(&Value);
  67     return init();
  68   }
  69
  70   unsigned operator++(int) {
  71     init();
  72     unsigned OldValue = Value;
  73     sys::AtomicIncrement(&Value);
  74     return OldValue;
  75   }
  76
  77   const Statistic &operator--() {
  78     sys::AtomicDecrement(&Value);
  79     return init();
  80   }
  81
  82   unsigned operator--(int) {
  83     init();
  84     unsigned OldValue = Value;
  85     sys::AtomicDecrement(&Value);
  86     return OldValue;
  87   }
  88
  89   const Statistic &operator+=(const unsigned &V) {
  90     if (!V) return *this;
  91     sys::AtomicAdd(&Value, V);
  92     return init();
  93   }
  94
  95   const Statistic &operator-=(const unsigned &V) {
  96     if (!V) return *this;
  97     sys::AtomicAdd(&Value, -V);
  98     return init();
  99   }
 100
 101   const Statistic &operator*=(const unsigned &V) {
 102     sys::AtomicMul(&Value, V);
 103     return init();
 104   }
 105
 106   const Statistic &operator/=(const unsigned &V) {
 107     sys::AtomicDiv(&Value, V);
 108     return init();
 109   }
 110
 111 #else  // Statistics are disabled in release builds.
 112
 113   const Statistic &operator=(unsigned Val) {
 114     return *this;
 115   }
 116
 117   const Statistic &operator++() {
 118     return *this;
 119   }
 120
 121   unsigned operator++(int) {
 122     return 0;
 123   }
 124
 125   const Statistic &operator--() {
 126     return *this;
 127   }
 128
 129   unsigned operator--(int) {
 130     return 0;
 131   }
 132
 133   const Statistic &operator+=(const unsigned &V) {
 134     return *this;
 135   }
 136
 137   const Statistic &operator-=(const unsigned &V) {
 138     return *this;
 139   }
 140
 141   const Statistic &operator*=(const unsigned &V) {
 142     return *this;
 143   }
 144
 145   const Statistic &operator/=(const unsigned &V) {
 146     return *this;
 147   }
 148
 149 #endif  // !defined(NDEBUG) || defined(LLVM_ENABLE_STATS)
 150
 151 protected:
 152   Statistic &init() {
 153     bool tmp = Initialized;
 154     sys::MemoryFence();
 155     if (!tmp) RegisterStatistic();
 156     TsanHappensAfter(this);
 157     return *this;
 158   }
 159   void RegisterStatistic();
 160 };
 161
 162 // STATISTIC - A macro to make definition of statistics really simple.  This
 163 // automatically passes the DEBUG_TYPE of the file into the statistic.
 164 #define STATISTIC(VARNAME, DESC) \
 165   static llvm::Statistic VARNAME = { DEBUG_TYPE, DESC, 0, 0 }
 166
 167 /// \brief Enable the collection and printing of statistics.
 168 void EnableStatistics();
 169
 170 /// \brief Check if statistics are enabled.
 171 bool AreStatisticsEnabled();
 172
 173 /// \brief Print statistics to the file returned by CreateInfoOutputFile().
 174 void PrintStatistics();
 175
 176 /// \brief Print statistics to the given output stream.
 177 void PrintStatistics(raw_ostream &OS);
 178
 179 } // End llvm namespace
 180
 181 #endif