Statistic.h revision 2dd93edfc221fe6d1e102cca694da01ca36b5d11 
1//===-- Support/Statistic.h - Easy way to expose stats ----------*- C++ -*-===//
2//
3// This file defines the 'Statistic' class, which is designed to be an easy way
4// to expose various success metrics from passes.  These statistics are printed
5// at the end of a run, when the -stats command line option is enabled on the
6// command line.
7//
8// This is useful for reporting information like the number of instructions
9// simplified, optimized or removed by various transformations, like this:
10//
11// static Statistic<> NumInstEliminated("GCSE - Number of instructions killed");
12//
13// Later, in the code: ++NumInstEliminated;
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef SUPPORT_STATISTIC_H
18#define SUPPORT_STATISTIC_H
19
20#include <iosfwd>
21
22// StatisticBase - Nontemplated base class for Statistic<> class...
23class StatisticBase {
24  const char *Name;
25  const char *Desc;
26  static unsigned NumStats;
27protected:
28  StatisticBase(const char *name, const char *desc) : Name(name), Desc(desc) {
29    ++NumStats;  // Keep track of how many stats are created...
30  }
31  virtual ~StatisticBase() {}
32
33  // destroy - Called by subclass dtor so that we can still invoke virtual
34  // functions on the subclass.
35  void destroy() const;
36
37  // printValue - Overridden by template class to print out the value type...
38  virtual void printValue(std::ostream &o) const = 0;
39
40  // hasSomeData - Return true if some data has been aquired.  Avoid printing
41  // lots of zero counts.
42  //
43  virtual bool hasSomeData() const = 0;
44};
45
46// Statistic Class - templated on the data type we are monitoring...
47template <typename DataType=unsigned>
48class Statistic : private StatisticBase {
49  DataType Value;
50
51  virtual void printValue(std::ostream &o) const { o << Value; }
52  virtual bool hasSomeData() const { return Value != DataType(); }
53public:
54  // Normal constructor, default initialize data item...
55  Statistic(const char *name, const char *desc)
56    : StatisticBase(name, desc), Value(DataType()) {}
57
58  // Constructor to provide an initial value...
59  Statistic(const DataType &Val, const char *name, const char *desc)
60    : StatisticBase(name, desc), Value(Val) {}
61
62  // Print information when destroyed, iff command line option is specified
63  ~Statistic() { destroy(); }
64
65  // Allow use of this class as the value itself...
66  operator DataType() const { return Value; }
67  const Statistic &operator=(DataType Val) { Value = Val; return *this; }
68  const Statistic &operator++() { ++Value; return *this; }
69  DataType operator++(int) { return Value++; }
70  const Statistic &operator+=(const DataType &V) { Value += V; return *this; }
71  const Statistic &operator-=(const DataType &V) { Value -= V; return *this; }
72};
73
74#endif
75