lib/Analysis/BlockFrequency.cpp

   1 //=======-------- BlockFrequency.cpp - 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/InitializePasses.h"
  15 #include "llvm/Analysis/BlockFrequencyImpl.h"
  16 #include "llvm/Analysis/BlockFrequency.h"
  17 #include "llvm/Analysis/LoopInfo.h"
  18 #include "llvm/Analysis/Passes.h"
  19 #include "llvm/Analysis/BranchProbabilityInfo.h"
  20
  21 using namespace llvm;
  22
  23 INITIALIZE_PASS_BEGIN(BlockFrequency, "block-freq", "Block Frequency Analysis",
  24                       true, true)
  25 INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfo)
  26 INITIALIZE_PASS_END(BlockFrequency, "block-freq", "Block Frequency Analysis",
  27                     true, true)
  28
  29 char BlockFrequency::ID = 0;
  30
  31
  32 BlockFrequency::BlockFrequency() : FunctionPass(ID) {
  33   initializeBlockFrequencyPass(*PassRegistry::getPassRegistry());
  34   BFI = new BlockFrequencyImpl<BasicBlock, Function, BranchProbabilityInfo>();
  35 }
  36
  37 BlockFrequency::~BlockFrequency() {
  38   delete BFI;
  39 }
  40
  41 void BlockFrequency::getAnalysisUsage(AnalysisUsage &AU) const {
  42   AU.addRequired<BranchProbabilityInfo>();
  43   AU.setPreservesAll();
  44 }
  45
  46 bool BlockFrequency::runOnFunction(Function &F) {
  47   BranchProbabilityInfo &BPI = getAnalysis<BranchProbabilityInfo>();
  48   BFI->doFunction(&F, &BPI);
  49   return false;
  50 }
  51
  52 /// getblockFreq - Return block frequency. Never return 0, value must be
  53 /// positive. Please note that initial frequency is equal to 1024. It means that
  54 /// we should not rely on the value itself, but only on the comparison to the
  55 /// other block frequencies. We do this to avoid using of floating points.
  56 ///
  57 uint32_t BlockFrequency::getBlockFreq(BasicBlock *BB) {
  58   return BFI->getBlockFreq(BB);
  59 }