lib/Support/Statistic.cpp

   1 //===-- Statistic.cpp - Easy way to expose stats information --------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the 'Statistic' class, which is designed to be an easy
  11 // way to expose various success metrics from passes.  These statistics are
  12 // printed at the end of a run, when the -stats command line option is enabled
  13 // 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<> NumInstEliminated("GCSE - Number of instructions killed");
  19 //
  20 // Later, in the code: ++NumInstEliminated;
  21 //
  22 //===----------------------------------------------------------------------===//
  23
  24 #include "llvm/ADT/Statistic.h"
  25 #include "llvm/Support/CommandLine.h"
  26 #include <sstream>
  27 #include <iostream>
  28 #include <algorithm>
  29 using namespace llvm;
  30
  31 // GetLibSupportInfoOutputFile - Return a file stream to print our output on...
  32 namespace llvm { extern std::ostream *GetLibSupportInfoOutputFile(); }
  33
  34 unsigned StatisticBase::NumStats = 0;
  35
  36 // -stats - Command line option to cause transformations to emit stats about
  37 // what they did.
  38 //
  39 static cl::opt<bool>
  40 Enabled("stats", cl::desc("Enable statistics output from program"));
  41
  42 struct StatRecord {
  43   std::string Value;
  44   const char *Name, *Desc;
  45
  46   StatRecord(const std::string &V, const char *N, const char *D)
  47     : Value(V), Name(N), Desc(D) {}
  48
  49   bool operator<(const StatRecord &SR) const {
  50     return std::strcmp(Name, SR.Name) < 0;
  51   }
  52
  53   void print(unsigned ValFieldSize, unsigned NameFieldSize,
  54              std::ostream &OS) {
  55     OS << std::string(ValFieldSize-Value.length(), ' ')
  56        << Value << " " << Name
  57        << std::string(NameFieldSize-std::strlen(Name), ' ')
  58        << " - " << Desc << "\n";
  59   }
  60 };
  61
  62 static std::vector<StatRecord> *AccumStats = 0;
  63
  64 // Out of line virtual dtor, to give the vtable etc a home.
  65 StatisticBase::~StatisticBase() {
  66 }
  67
  68 // Print information when destroyed, iff command line option is specified
  69 void StatisticBase::destroy() const {
  70   if (Enabled && hasSomeData()) {
  71     if (AccumStats == 0)
  72       AccumStats = new std::vector<StatRecord>();
  73
  74     std::ostringstream Out;
  75     printValue(Out);
  76     AccumStats->push_back(StatRecord(Out.str(), Name, Desc));
  77   }
  78
  79   if (--NumStats == 0 && AccumStats) {
  80     std::ostream *OutStream = GetLibSupportInfoOutputFile();
  81
  82     // Figure out how long the biggest Value and Name fields are...
  83     unsigned MaxNameLen = 0, MaxValLen = 0;
  84     for (unsigned i = 0, e = AccumStats->size(); i != e; ++i) {
  85       MaxValLen = std::max(MaxValLen,
  86                            (unsigned)(*AccumStats)[i].Value.length());
  87       MaxNameLen = std::max(MaxNameLen,
  88                             (unsigned)std::strlen((*AccumStats)[i].Name));
  89     }
  90
  91     // Sort the fields...
  92     std::stable_sort(AccumStats->begin(), AccumStats->end());
  93
  94     // Print out the statistics header...
  95     *OutStream << "===" << std::string(73, '-') << "===\n"
  96                << "                          ... Statistics Collected ...\n"
  97                << "===" << std::string(73, '-') << "===\n\n";
  98
  99     // Print all of the statistics accumulated...
 100     for (unsigned i = 0, e = AccumStats->size(); i != e; ++i)
 101       (*AccumStats)[i].print(MaxValLen, MaxNameLen, *OutStream);
 102
 103     *OutStream << std::endl;  // Flush the output stream...
 104
 105     // Free all accumulated statistics...
 106     delete AccumStats;
 107     AccumStats = 0;
 108     if (OutStream != &std::cerr && OutStream != &std::cout)
 109       delete OutStream;   // Close the file...
 110   }
 111 }