lib/Support/BlockFrequency.cpp

   1 //====--------------- lib/Support/BlockFrequency.cpp -----------*- 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 #include "llvm/Support/BranchProbability.h"
  15 #include "llvm/Support/BlockFrequency.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 #include <cassert>
  18
  19 using namespace llvm;
  20
  21 BlockFrequency &BlockFrequency::operator*=(const BranchProbability &Prob) {
  22   Frequency = Prob.scale(Frequency);
  23   return *this;
  24 }
  25
  26 const BlockFrequency
  27 BlockFrequency::operator*(const BranchProbability &Prob) const {
  28   BlockFrequency Freq(Frequency);
  29   Freq *= Prob;
  30   return Freq;
  31 }
  32
  33 BlockFrequency &BlockFrequency::operator/=(const BranchProbability &Prob) {
  34   Frequency = Prob.scaleByInverse(Frequency);
  35   return *this;
  36 }
  37
  38 BlockFrequency BlockFrequency::operator/(const BranchProbability &Prob) const {
  39   BlockFrequency Freq(Frequency);
  40   Freq /= Prob;
  41   return Freq;
  42 }
  43
  44 BlockFrequency &BlockFrequency::operator+=(const BlockFrequency &Freq) {
  45   uint64_t Before = Freq.Frequency;
  46   Frequency += Freq.Frequency;
  47
  48   // If overflow, set frequency to the maximum value.
  49   if (Frequency < Before)
  50     Frequency = UINT64_MAX;
  51
  52   return *this;
  53 }
  54
  55 const BlockFrequency
  56 BlockFrequency::operator+(const BlockFrequency &Prob) const {
  57   BlockFrequency Freq(Frequency);
  58   Freq += Prob;
  59   return Freq;
  60 }
  61
  62 BlockFrequency &BlockFrequency::operator>>=(const unsigned count) {
  63   // Frequency can never be 0 by design.
  64   assert(Frequency != 0);
  65
  66   // Shift right by count.
  67   Frequency >>= count;
  68
  69   // Saturate to 1 if we are 0.
  70   Frequency |= Frequency == 0;
  71   return *this;
  72 }