LLVM  8.0.0svn
IntEqClasses.h
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1 //===-- llvm/ADT/IntEqClasses.h - Equiv. Classes of Integers ----*- 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 // Equivalence classes for small integers. This is a mapping of the integers
11 // 0 .. N-1 into M equivalence classes numbered 0 .. M-1.
12 //
13 // Initially each integer has its own equivalence class. Classes are joined by
14 // passing a representative member of each class to join().
15 //
16 // Once the classes are built, compress() will number them 0 .. M-1 and prevent
17 // further changes.
18 //
19 //===----------------------------------------------------------------------===//
20 
21 #ifndef LLVM_ADT_INTEQCLASSES_H
22 #define LLVM_ADT_INTEQCLASSES_H
23 
24 #include "llvm/ADT/SmallVector.h"
25 
26 namespace llvm {
27 
28 class IntEqClasses {
29  /// EC - When uncompressed, map each integer to a smaller member of its
30  /// equivalence class. The class leader is the smallest member and maps to
31  /// itself.
32  ///
33  /// When compressed, EC[i] is the equivalence class of i.
35 
36  /// NumClasses - The number of equivalence classes when compressed, or 0 when
37  /// uncompressed.
38  unsigned NumClasses;
39 
40 public:
41  /// IntEqClasses - Create an equivalence class mapping for 0 .. N-1.
42  IntEqClasses(unsigned N = 0) : NumClasses(0) { grow(N); }
43 
44  /// grow - Increase capacity to hold 0 .. N-1, putting new integers in unique
45  /// equivalence classes.
46  /// This requires an uncompressed map.
47  void grow(unsigned N);
48 
49  /// clear - Clear all classes so that grow() will assign a unique class to
50  /// every integer.
51  void clear() {
52  EC.clear();
53  NumClasses = 0;
54  }
55 
56  /// Join the equivalence classes of a and b. After joining classes,
57  /// findLeader(a) == findLeader(b). This requires an uncompressed map.
58  /// Returns the new leader.
59  unsigned join(unsigned a, unsigned b);
60 
61  /// findLeader - Compute the leader of a's equivalence class. This is the
62  /// smallest member of the class.
63  /// This requires an uncompressed map.
64  unsigned findLeader(unsigned a) const;
65 
66  /// compress - Compress equivalence classes by numbering them 0 .. M.
67  /// This makes the equivalence class map immutable.
68  void compress();
69 
70  /// getNumClasses - Return the number of equivalence classes after compress()
71  /// was called.
72  unsigned getNumClasses() const { return NumClasses; }
73 
74  /// operator[] - Return a's equivalence class number, 0 .. getNumClasses()-1.
75  /// This requires a compressed map.
76  unsigned operator[](unsigned a) const {
77  assert(NumClasses && "operator[] called before compress()");
78  return EC[a];
79  }
80 
81  /// uncompress - Change back to the uncompressed representation that allows
82  /// editing.
83  void uncompress();
84 };
85 
86 } // End llvm namespace
87 
88 #endif
unsigned operator[](unsigned a) const
operator[] - Return a's equivalence class number, 0 .
Definition: IntEqClasses.h:76
unsigned findLeader(unsigned a) const
findLeader - Compute the leader of a's equivalence class.
void grow(unsigned N)
grow - Increase capacity to hold 0 .
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
IntEqClasses(unsigned N=0)
IntEqClasses - Create an equivalence class mapping for 0 .. N-1.
Definition: IntEqClasses.h:42
void compress()
compress - Compress equivalence classes by numbering them 0 .
void clear()
clear - Clear all classes so that grow() will assign a unique class to every integer.
Definition: IntEqClasses.h:51
void uncompress()
uncompress - Change back to the uncompressed representation that allows editing.
unsigned getNumClasses() const
getNumClasses - Return the number of equivalence classes after compress() was called.
Definition: IntEqClasses.h:72
unsigned join(unsigned a, unsigned b)
Join the equivalence classes of a and b.
#define N
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())