1 ///===- LazyMachineBlockFrequencyInfo.cpp - Lazy Machine Block Frequency --===// 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 /// \file 9 /// This is an alternative analysis pass to MachineBlockFrequencyInfo. The 10 /// difference is that with this pass the block frequencies are not computed 11 /// when the analysis pass is executed but rather when the BFI result is 12 /// explicitly requested by the analysis client. 13 /// 14 ///===---------------------------------------------------------------------===// 15 16 #include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h" 17 #include "llvm/InitializePasses.h" 18 19 using namespace llvm; 20 21 #define DEBUG_TYPE "lazy-machine-block-freq" 22 23 INITIALIZE_PASS_BEGIN(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE, 24 "Lazy Machine Block Frequency Analysis", true, true) 25 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo) 26 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) 27 INITIALIZE_PASS_END(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE, 28 "Lazy Machine Block Frequency Analysis", true, true) 29 30 char LazyMachineBlockFrequencyInfoPass::ID = 0; 31 32 LazyMachineBlockFrequencyInfoPass::LazyMachineBlockFrequencyInfoPass() 33 : MachineFunctionPass(ID) { 34 initializeLazyMachineBlockFrequencyInfoPassPass( 35 *PassRegistry::getPassRegistry()); 36 } 37 38 void LazyMachineBlockFrequencyInfoPass::print(raw_ostream &OS, 39 const Module *M) const { 40 getBFI().print(OS, M); 41 } 42 43 void LazyMachineBlockFrequencyInfoPass::getAnalysisUsage( 44 AnalysisUsage &AU) const { 45 AU.addRequired<MachineBranchProbabilityInfo>(); 46 AU.setPreservesAll(); 47 MachineFunctionPass::getAnalysisUsage(AU); 48 } 49 50 void LazyMachineBlockFrequencyInfoPass::releaseMemory() { 51 OwnedMBFI.reset(); 52 OwnedMLI.reset(); 53 OwnedMDT.reset(); 54 } 55 56 MachineBlockFrequencyInfo & 57 LazyMachineBlockFrequencyInfoPass::calculateIfNotAvailable() const { 58 auto *MBFI = getAnalysisIfAvailable<MachineBlockFrequencyInfo>(); 59 if (MBFI) { 60 LLVM_DEBUG(dbgs() << "MachineBlockFrequencyInfo is available\n"); 61 return *MBFI; 62 } 63 64 auto &MBPI = getAnalysis<MachineBranchProbabilityInfo>(); 65 auto *MLI = getAnalysisIfAvailable<MachineLoopInfo>(); 66 auto *MDT = getAnalysisIfAvailable<MachineDominatorTree>(); 67 LLVM_DEBUG(dbgs() << "Building MachineBlockFrequencyInfo on the fly\n"); 68 LLVM_DEBUG(if (MLI) dbgs() << "LoopInfo is available\n"); 69 70 if (!MLI) { 71 LLVM_DEBUG(dbgs() << "Building LoopInfo on the fly\n"); 72 // First create a dominator tree. 73 LLVM_DEBUG(if (MDT) dbgs() << "DominatorTree is available\n"); 74 75 if (!MDT) { 76 LLVM_DEBUG(dbgs() << "Building DominatorTree on the fly\n"); 77 OwnedMDT = std::make_unique<MachineDominatorTree>(); 78 OwnedMDT->getBase().recalculate(*MF); 79 MDT = OwnedMDT.get(); 80 } 81 82 // Generate LoopInfo from it. 83 OwnedMLI = std::make_unique<MachineLoopInfo>(); 84 OwnedMLI->getBase().analyze(MDT->getBase()); 85 MLI = OwnedMLI.get(); 86 } 87 88 OwnedMBFI = std::make_unique<MachineBlockFrequencyInfo>(); 89 OwnedMBFI->calculate(*MF, MBPI, *MLI); 90 return *OwnedMBFI.get(); 91 } 92 93 bool LazyMachineBlockFrequencyInfoPass::runOnMachineFunction( 94 MachineFunction &F) { 95 MF = &F; 96 return false; 97 } 98