1 //===-------- BlockFrequency.h - Block Frequency Wrapper --------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements Block Frequency class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_SUPPORT_BLOCKFREQUENCY_H
14 #define LLVM_SUPPORT_BLOCKFREQUENCY_H
15 
16 #include <cstdint>
17 
18 namespace llvm {
19 
20 class BranchProbability;
21 
22 // This class represents Block Frequency as a 64-bit value.
23 class BlockFrequency {
24   uint64_t Frequency;
25 
26 public:
Frequency(Freq)27   BlockFrequency(uint64_t Freq = 0) : Frequency(Freq) { }
28 
29   /// Returns the maximum possible frequency, the saturation value.
getMaxFrequency()30   static uint64_t getMaxFrequency() { return -1ULL; }
31 
32   /// Returns the frequency as a fixpoint number scaled by the entry
33   /// frequency.
getFrequency()34   uint64_t getFrequency() const { return Frequency; }
35 
36   /// Multiplies with a branch probability. The computation will never
37   /// overflow.
38   BlockFrequency &operator*=(BranchProbability Prob);
39   BlockFrequency operator*(BranchProbability Prob) const;
40 
41   /// Divide by a non-zero branch probability using saturating
42   /// arithmetic.
43   BlockFrequency &operator/=(BranchProbability Prob);
44   BlockFrequency operator/(BranchProbability Prob) const;
45 
46   /// Adds another block frequency using saturating arithmetic.
47   BlockFrequency &operator+=(BlockFrequency Freq);
48   BlockFrequency operator+(BlockFrequency Freq) const;
49 
50   /// Subtracts another block frequency using saturating arithmetic.
51   BlockFrequency &operator-=(BlockFrequency Freq);
52   BlockFrequency operator-(BlockFrequency Freq) const;
53 
54   /// Shift block frequency to the right by count digits saturating to 1.
55   BlockFrequency &operator>>=(const unsigned count);
56 
57   bool operator<(BlockFrequency RHS) const {
58     return Frequency < RHS.Frequency;
59   }
60 
61   bool operator<=(BlockFrequency RHS) const {
62     return Frequency <= RHS.Frequency;
63   }
64 
65   bool operator>(BlockFrequency RHS) const {
66     return Frequency > RHS.Frequency;
67   }
68 
69   bool operator>=(BlockFrequency RHS) const {
70     return Frequency >= RHS.Frequency;
71   }
72 
73   bool operator==(BlockFrequency RHS) const {
74     return Frequency == RHS.Frequency;
75   }
76 };
77 
78 }
79 
80 #endif
81