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/CodeGen/MachineBranchProbabilityInfo.h" 18 #include "llvm/InitializePasses.h" 19 20 using namespace llvm; 21 22 #define DEBUG_TYPE "lazy-machine-block-freq" 23 24 INITIALIZE_PASS_BEGIN(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE, 25 "Lazy Machine Block Frequency Analysis", true, true) 26 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo) 27 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) 28 INITIALIZE_PASS_END(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE, 29 "Lazy Machine Block Frequency Analysis", true, true) 30 31 char LazyMachineBlockFrequencyInfoPass::ID = 0; 32 33 LazyMachineBlockFrequencyInfoPass::LazyMachineBlockFrequencyInfoPass() 34 : MachineFunctionPass(ID) { 35 initializeLazyMachineBlockFrequencyInfoPassPass( 36 *PassRegistry::getPassRegistry()); 37 } 38 39 void LazyMachineBlockFrequencyInfoPass::print(raw_ostream &OS, 40 const Module *M) const { 41 getBFI().print(OS, M); 42 } 43 44 void LazyMachineBlockFrequencyInfoPass::getAnalysisUsage( 45 AnalysisUsage &AU) const { 46 AU.addRequired<MachineBranchProbabilityInfo>(); 47 AU.setPreservesAll(); 48 MachineFunctionPass::getAnalysisUsage(AU); 49 } 50 51 void LazyMachineBlockFrequencyInfoPass::releaseMemory() { 52 OwnedMBFI.reset(); 53 OwnedMLI.reset(); 54 OwnedMDT.reset(); 55 } 56 57 MachineBlockFrequencyInfo & 58 LazyMachineBlockFrequencyInfoPass::calculateIfNotAvailable() const { 59 auto *MBFI = getAnalysisIfAvailable<MachineBlockFrequencyInfo>(); 60 if (MBFI) { 61 LLVM_DEBUG(dbgs() << "MachineBlockFrequencyInfo is available\n"); 62 return *MBFI; 63 } 64 65 auto &MBPI = getAnalysis<MachineBranchProbabilityInfo>(); 66 auto *MLI = getAnalysisIfAvailable<MachineLoopInfo>(); 67 auto *MDT = getAnalysisIfAvailable<MachineDominatorTree>(); 68 LLVM_DEBUG(dbgs() << "Building MachineBlockFrequencyInfo on the fly\n"); 69 LLVM_DEBUG(if (MLI) dbgs() << "LoopInfo is available\n"); 70 71 if (!MLI) { 72 LLVM_DEBUG(dbgs() << "Building LoopInfo on the fly\n"); 73 // First create a dominator tree. 74 LLVM_DEBUG(if (MDT) dbgs() << "DominatorTree is available\n"); 75 76 if (!MDT) { 77 LLVM_DEBUG(dbgs() << "Building DominatorTree on the fly\n"); 78 OwnedMDT = std::make_unique<MachineDominatorTree>(); 79 OwnedMDT->getBase().recalculate(*MF); 80 MDT = OwnedMDT.get(); 81 } 82 83 // Generate LoopInfo from it. 84 OwnedMLI = std::make_unique<MachineLoopInfo>(); 85 OwnedMLI->getBase().analyze(MDT->getBase()); 86 MLI = OwnedMLI.get(); 87 } 88 89 OwnedMBFI = std::make_unique<MachineBlockFrequencyInfo>(); 90 OwnedMBFI->calculate(*MF, MBPI, *MLI); 91 return *OwnedMBFI; 92 } 93 94 bool LazyMachineBlockFrequencyInfoPass::runOnMachineFunction( 95 MachineFunction &F) { 96 MF = &F; 97 return false; 98 } 99