llvm/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 #include "llvm/InitializePasses.h"
  21
  22 using namespace llvm;
  23
  24 #define DEBUG_TYPE "lazy-block-freq"
  25
  26 INITIALIZE_PASS_BEGIN(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
  27                       "Lazy Block Frequency Analysis", true, true)
  28 INITIALIZE_PASS_DEPENDENCY(LazyBPIPass)
  29 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
  30 INITIALIZE_PASS_END(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
  31                     "Lazy Block Frequency Analysis", true, true)
  32
  33 char LazyBlockFrequencyInfoPass::ID = 0;
  34
  35 LazyBlockFrequencyInfoPass::LazyBlockFrequencyInfoPass() : FunctionPass(ID) {
  36   initializeLazyBlockFrequencyInfoPassPass(*PassRegistry::getPassRegistry());
  37 }
  38
  39 void LazyBlockFrequencyInfoPass::print(raw_ostream &OS, const Module *) const {
  40   LBFI.getCalculated().print(OS);
  41 }
  42
  43 void LazyBlockFrequencyInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
  44   LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
  45   // We require DT so it's available when LI is available. The LI updating code
  46   // asserts that DT is also present so if we don't make sure that we have DT
  47   // here, that assert will trigger.
  48   AU.addRequiredTransitive<DominatorTreeWrapperPass>();
  49   AU.addRequiredTransitive<LoopInfoWrapperPass>();
  50   AU.setPreservesAll();
  51 }
  52
  53 void LazyBlockFrequencyInfoPass::releaseMemory() { LBFI.releaseMemory(); }
  54
  55 bool LazyBlockFrequencyInfoPass::runOnFunction(Function &F) {
  56   auto &BPIPass = getAnalysis<LazyBranchProbabilityInfoPass>();
  57   LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
  58   LBFI.setAnalysis(&F, &BPIPass, &LI);
  59   return false;
  60 }
  61
  62 void LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AnalysisUsage &AU) {
  63   LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
  64   AU.addRequiredTransitive<LazyBlockFrequencyInfoPass>();
  65   AU.addRequiredTransitive<LoopInfoWrapperPass>();
  66 }
  67
  68 void llvm::initializeLazyBFIPassPass(PassRegistry &Registry) {
  69   initializeLazyBPIPassPass(Registry);
  70   INITIALIZE_PASS_DEPENDENCY(LazyBlockFrequencyInfoPass);
  71   INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
  72 }