1 //===-------- BlockFrequency.h - Block Frequency Wrapper --------*- 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 // This file implements Block Frequency class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_BLOCKFREQUENCY_H
15 #define LLVM_SUPPORT_BLOCKFREQUENCY_H
16 
17 #include "llvm/Support/DataTypes.h"
18 
19 namespace llvm {
20 
21 class raw_ostream;
22 class BranchProbability;
23 
24 // This class represents Block Frequency as a 64-bit value.
25 class BlockFrequency {
26   uint64_t Frequency;
27 
28 public:
Frequency(Freq)29   BlockFrequency(uint64_t Freq = 0) : Frequency(Freq) { }
30 
31   /// \brief Returns the maximum possible frequency, the saturation value.
getMaxFrequency()32   static uint64_t getMaxFrequency() { return -1ULL; }
33 
34   /// \brief Returns the frequency as a fixpoint number scaled by the entry
35   /// frequency.
getFrequency()36   uint64_t getFrequency() const { return Frequency; }
37 
38   /// \brief Multiplies with a branch probability. The computation will never
39   /// overflow.
40   BlockFrequency &operator*=(const BranchProbability &Prob);
41   const BlockFrequency operator*(const BranchProbability &Prob) const;
42 
43   /// \brief Divide by a non-zero branch probability using saturating
44   /// arithmetic.
45   BlockFrequency &operator/=(const BranchProbability &Prob);
46   BlockFrequency operator/(const BranchProbability &Prob) const;
47 
48   /// \brief Adds another block frequency using saturating arithmetic.
49   BlockFrequency &operator+=(const BlockFrequency &Freq);
50   const BlockFrequency operator+(const BlockFrequency &Freq) const;
51 
52   /// \brief Shift block frequency to the right by count digits saturating to 1.
53   BlockFrequency &operator>>=(const unsigned count);
54 
55   bool operator<(const BlockFrequency &RHS) const {
56     return Frequency < RHS.Frequency;
57   }
58 
59   bool operator<=(const BlockFrequency &RHS) const {
60     return Frequency <= RHS.Frequency;
61   }
62 
63   bool operator>(const BlockFrequency &RHS) const {
64     return Frequency > RHS.Frequency;
65   }
66 
67   bool operator>=(const BlockFrequency &RHS) const {
68     return Frequency >= RHS.Frequency;
69   }
70 };
71 
72 }
73 
74 #endif
75