lib/Analysis/LazyBlockFrequencyInfo.cpp

   1 //===- LazyBlockFrequencyInfo.cpp - Lazy Block Frequency Analysis ---------===//
   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 is an alternative analysis pass to BlockFrequencyInfoWrapperPass.  The
  10 // difference is that with this pass the block frequencies are not computed when
  11 // the analysis pass is executed but rather when the BFI result is explicitly
  12 // requested by the analysis client.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "llvm/Analysis/LazyBlockFrequencyInfo.h"
  17 #include "llvm/Analysis/LazyBranchProbabilityInfo.h"
  18 #include "llvm/Analysis/LoopInfo.h"
  19 #include "llvm/IR/Dominators.h"
  20
  21 using namespace llvm;
  22
  23 #define DEBUG_TYPE "lazy-block-freq"
  24
  25 INITIALIZE_PASS_BEGIN(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
  26                       "Lazy Block Frequency Analysis", true, true)
  27 INITIALIZE_PASS_DEPENDENCY(LazyBPIPass)
  28 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
  29 INITIALIZE_PASS_END(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
  30                     "Lazy Block Frequency Analysis", true, true)
  31
  32 char LazyBlockFrequencyInfoPass::ID = 0;
  33
  34 LazyBlockFrequencyInfoPass::LazyBlockFrequencyInfoPass() : FunctionPass(ID) {
  35   initializeLazyBlockFrequencyInfoPassPass(*PassRegistry::getPassRegistry());
  36 }
  37
  38 void LazyBlockFrequencyInfoPass::print(raw_ostream &OS, const Module *) const {
  39   LBFI.getCalculated().print(OS);
  40 }
  41
  42 void LazyBlockFrequencyInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
  43   LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
  44   // We require DT so it's available when LI is available. The LI updating code
  45   // asserts that DT is also present so if we don't make sure that we have DT
  46   // here, that assert will trigger.
  47   AU.addRequired<DominatorTreeWrapperPass>();
  48   AU.addRequired<LoopInfoWrapperPass>();
  49   AU.setPreservesAll();
  50 }
  51
  52 void LazyBlockFrequencyInfoPass::releaseMemory() { LBFI.releaseMemory(); }
  53
  54 bool LazyBlockFrequencyInfoPass::runOnFunction(Function &F) {
  55   auto &BPIPass = getAnalysis<LazyBranchProbabilityInfoPass>();
  56   LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
  57   LBFI.setAnalysis(&F, &BPIPass, &LI);
  58   return false;
  59 }
  60
  61 void LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AnalysisUsage &AU) {
  62   LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
  63   AU.addRequired<LazyBlockFrequencyInfoPass>();
  64   AU.addRequired<LoopInfoWrapperPass>();
  65 }
  66
  67 void llvm::initializeLazyBFIPassPass(PassRegistry &Registry) {
  68   initializeLazyBPIPassPass(Registry);
  69   INITIALIZE_PASS_DEPENDENCY(LazyBlockFrequencyInfoPass);
  70   INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
  71 }