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 // Print information when destroyed, iff command line option is specified
65 void StatisticBase::destroy() const {
66   if (Enabled && hasSomeData()) {
67     if (AccumStats == 0)
68       AccumStats = new std::vector<StatRecord>();
69 
70     std::ostringstream Out;
71     printValue(Out);
72     AccumStats->push_back(StatRecord(Out.str(), Name, Desc));
73   }
74 
75   if (--NumStats == 0 && AccumStats) {
76     std::ostream *OutStream = GetLibSupportInfoOutputFile();
77 
78     // Figure out how long the biggest Value and Name fields are...
79     unsigned MaxNameLen = 0, MaxValLen = 0;
80     for (unsigned i = 0, e = AccumStats->size(); i != e; ++i) {
81       MaxValLen = std::max(MaxValLen,
82                            (unsigned)(*AccumStats)[i].Value.length());
83       MaxNameLen = std::max(MaxNameLen,
84                             (unsigned)std::strlen((*AccumStats)[i].Name));
85     }
86 
87     // Sort the fields...
88     std::stable_sort(AccumStats->begin(), AccumStats->end());
89 
90     // Print out the statistics header...
91     *OutStream << "===" << std::string(73, '-') << "===\n"
92                << "                          ... Statistics Collected ...\n"
93                << "===" << std::string(73, '-') << "===\n\n";
94 
95     // Print all of the statistics accumulated...
96     for (unsigned i = 0, e = AccumStats->size(); i != e; ++i)
97       (*AccumStats)[i].print(MaxValLen, MaxNameLen, *OutStream);
98 
99     *OutStream << std::endl;  // Flush the output stream...
100 
101     // Free all accumulated statistics...
102     delete AccumStats;
103     AccumStats = 0;
104     if (OutStream != &std::cerr && OutStream != &std::cout)
105       delete OutStream;   // Close the file...
106   }
107 }
108