lib/Analysis/LazyBranchProbabilityInfo.cpp

   1 //===- LazyBranchProbabilityInfo.cpp - Lazy Branch Probability 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 // This is an alternative analysis pass to BranchProbabilityInfoWrapperPass.
  11 // The difference is that with this pass the branch probabilities are not
  12 // computed when the analysis pass is executed but rather when the BPI results
  13 // is explicitly requested by the analysis client.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/Analysis/LazyBranchProbabilityInfo.h"
  18 #include "llvm/Analysis/LoopInfo.h"
  19
  20 using namespace llvm;
  21
  22 #define DEBUG_TYPE "lazy-branch-prob"
  23
  24 INITIALIZE_PASS_BEGIN(LazyBranchProbabilityInfoPass, DEBUG_TYPE,
  25                       "Lazy Branch Probability Analysis", true, true)
  26 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
  27 INITIALIZE_PASS_END(LazyBranchProbabilityInfoPass, DEBUG_TYPE,
  28                     "Lazy Branch Probability Analysis", true, true)
  29
  30 char LazyBranchProbabilityInfoPass::ID = 0;
  31
  32 LazyBranchProbabilityInfoPass::LazyBranchProbabilityInfoPass()
  33     : FunctionPass(ID) {
  34   initializeLazyBranchProbabilityInfoPassPass(*PassRegistry::getPassRegistry());
  35 }
  36
  37 void LazyBranchProbabilityInfoPass::print(raw_ostream &OS,
  38                                           const Module *) const {
  39   LBPI->getCalculated().print(OS);
  40 }
  41
  42 void LazyBranchProbabilityInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
  43   AU.addRequired<LoopInfoWrapperPass>();
  44   AU.setPreservesAll();
  45 }
  46
  47 void LazyBranchProbabilityInfoPass::releaseMemory() { LBPI.reset(); }
  48
  49 bool LazyBranchProbabilityInfoPass::runOnFunction(Function &F) {
  50   LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
  51   LBPI = llvm::make_unique<LazyBranchProbabilityInfo>(&F, &LI);
  52   return false;
  53 }
  54
  55 void LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AnalysisUsage &AU) {
  56   AU.addRequired<LazyBranchProbabilityInfoPass>();
  57   AU.addRequired<LoopInfoWrapperPass>();
  58 }
  59
  60 void llvm::initializeLazyBPIPassPass(PassRegistry &Registry) {
  61   INITIALIZE_PASS_DEPENDENCY(LazyBranchProbabilityInfoPass);
  62   INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
  63 }