Statistic.h revision ac0b6ae358944ae8b2b5a11dc08f52c3ed89f2da 
1//===-- llvm/ADT/Statistic.h - Easy way to expose stats ---------*- C++ -*-===//
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 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 <ostream>
30#include "llvm/Support/Compiler.h"
31
32namespace llvm {
33
34// StatisticBase - Nontemplated base class for Statistic class...
35class StatisticBase {
36  const char *Name;
37  const char *Desc;
38  static unsigned NumStats;
39protected:
40  StatisticBase(const char *name, const char *desc) : Name(name), Desc(desc) {
41    ++NumStats;  // Keep track of how many stats are created...
42  }
43  // Out of line virtual dtor, to give the vtable etc a home.
44  virtual ~StatisticBase();
45
46  // destroy - Called by subclass dtor so that we can still invoke virtual
47  // functions on the subclass.
48  void destroy() const;
49
50  // printValue - Overridden by template class to print out the value type...
51  virtual void printValue(std::ostream &o) const = 0;
52
53  // hasSomeData - Return true if some data has been aquired.  Avoid printing
54  // lots of zero counts.
55  //
56  virtual bool hasSomeData() const = 0;
57};
58
59// Statistic Class - templated on the data type we are monitoring...
60class Statistic : private StatisticBase {
61  unsigned Value;
62
63  virtual void printValue(std::ostream &o) const { o << Value; }
64  virtual bool hasSomeData() const { return Value != 0; }
65public:
66  // Normal constructor, default initialize data item...
67  Statistic(const char *name, const char *desc)
68    : StatisticBase(name, desc), Value(0) {}
69
70  // Constructor to provide an initial value...
71  Statistic(const unsigned &Val, const char *name, const char *desc)
72    : StatisticBase(name, desc), Value(Val) {}
73
74  // Print information when destroyed, iff command line option is specified
75  ~Statistic() { destroy(); }
76
77  // Allow use of this class as the value itself...
78  operator unsigned() const { return Value; }
79  const Statistic &operator=(unsigned Val) { Value = Val; return *this; }
80  const Statistic &operator++() { ++Value; return *this; }
81  unsigned operator++(int) { return Value++; }
82  const Statistic &operator--() { --Value; return *this; }
83  unsigned operator--(int) { return Value--; }
84  const Statistic &operator+=(const unsigned &V) { Value += V; return *this; }
85  const Statistic &operator-=(const unsigned &V) { Value -= V; return *this; }
86  const Statistic &operator*=(const unsigned &V) { Value *= V; return *this; }
87  const Statistic &operator/=(const unsigned &V) { Value /= V; return *this; }
88};
89
90} // End llvm namespace
91
92#endif
93