lib/CodeGen/MachineBlockFrequencyInfo.cpp

   1 //====----- MachineBlockFrequencyInfo.cpp - Machine Block Frequency Analysis ----====//
   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 // Loops should be simplified before this analysis.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
  15 #include "llvm/Analysis/BlockFrequencyImpl.h"
  16 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
  17 #include "llvm/CodeGen/Passes.h"
  18 #include "llvm/InitializePasses.h"
  19
  20 using namespace llvm;
  21
  22 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, "machine-block-freq",
  23                       "Machine Block Frequency Analysis", true, true)
  24 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
  25 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, "machine-block-freq",
  26                     "Machine Block Frequency Analysis", true, true)
  27
  28 char MachineBlockFrequencyInfo::ID = 0;
  29
  30
  31 MachineBlockFrequencyInfo::MachineBlockFrequencyInfo() : MachineFunctionPass(ID) {
  32   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
  33   MBFI = new BlockFrequencyImpl<MachineBasicBlock, MachineFunction,
  34                                 MachineBranchProbabilityInfo>();
  35 }
  36
  37 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() {
  38   delete MBFI;
  39 }
  40
  41 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
  42   AU.addRequired<MachineBranchProbabilityInfo>();
  43   AU.setPreservesAll();
  44   MachineFunctionPass::getAnalysisUsage(AU);
  45 }
  46
  47 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
  48   MachineBranchProbabilityInfo &MBPI = getAnalysis<MachineBranchProbabilityInfo>();
  49   MBFI->doFunction(&F, &MBPI);
  50   return false;
  51 }
  52
  53 /// getblockFreq - Return block frequency. Return 0 if we don't have the
  54 /// information. Please note that initial frequency is equal to 1024. It means
  55 /// that we should not rely on the value itself, but only on the comparison to
  56 /// the other block frequencies. We do this to avoid using of floating points.
  57 ///
  58 BlockFrequency MachineBlockFrequencyInfo::
  59 getBlockFreq(const MachineBasicBlock *MBB) const {
  60   return MBFI->getBlockFreq(MBB);
  61 }