1 //===- TailDuplication.cpp - Duplicate blocks into predecessors' tails ----===// 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 /// \file This pass duplicates basic blocks ending in unconditional branches 10 /// into the tails of their predecessors, using the TailDuplicator utility 11 /// class. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/Analysis/ProfileSummaryInfo.h" 16 #include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h" 17 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h" 18 #include "llvm/CodeGen/MachineFunction.h" 19 #include "llvm/CodeGen/MachineFunctionPass.h" 20 #include "llvm/CodeGen/MachineRegisterInfo.h" 21 #include "llvm/CodeGen/Passes.h" 22 #include "llvm/CodeGen/TailDuplicator.h" 23 #include "llvm/InitializePasses.h" 24 #include "llvm/Pass.h" 25 26 using namespace llvm; 27 28 #define DEBUG_TYPE "tailduplication" 29 30 namespace { 31 32 class TailDuplicateBase : public MachineFunctionPass { 33 TailDuplicator Duplicator; 34 bool PreRegAlloc; 35 public: 36 TailDuplicateBase(char &PassID, bool PreRegAlloc) 37 : MachineFunctionPass(PassID), PreRegAlloc(PreRegAlloc) {} 38 39 bool runOnMachineFunction(MachineFunction &MF) override; 40 41 void getAnalysisUsage(AnalysisUsage &AU) const override { 42 AU.addRequired<MachineBranchProbabilityInfo>(); 43 AU.addRequired<LazyMachineBlockFrequencyInfoPass>(); 44 AU.addRequired<ProfileSummaryInfoWrapperPass>(); 45 MachineFunctionPass::getAnalysisUsage(AU); 46 } 47 }; 48 49 class TailDuplicate : public TailDuplicateBase { 50 public: 51 static char ID; 52 TailDuplicate() : TailDuplicateBase(ID, false) { 53 initializeTailDuplicatePass(*PassRegistry::getPassRegistry()); 54 } 55 }; 56 57 class EarlyTailDuplicate : public TailDuplicateBase { 58 public: 59 static char ID; 60 EarlyTailDuplicate() : TailDuplicateBase(ID, true) { 61 initializeEarlyTailDuplicatePass(*PassRegistry::getPassRegistry()); 62 } 63 64 MachineFunctionProperties getClearedProperties() const override { 65 return MachineFunctionProperties() 66 .set(MachineFunctionProperties::Property::NoPHIs); 67 } 68 }; 69 70 } // end anonymous namespace 71 72 char TailDuplicate::ID; 73 char EarlyTailDuplicate::ID; 74 75 char &llvm::TailDuplicateID = TailDuplicate::ID; 76 char &llvm::EarlyTailDuplicateID = EarlyTailDuplicate::ID; 77 78 INITIALIZE_PASS(TailDuplicate, DEBUG_TYPE, "Tail Duplication", false, false) 79 INITIALIZE_PASS(EarlyTailDuplicate, "early-tailduplication", 80 "Early Tail Duplication", false, false) 81 82 bool TailDuplicateBase::runOnMachineFunction(MachineFunction &MF) { 83 if (skipFunction(MF.getFunction())) 84 return false; 85 86 auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>(); 87 auto *PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI(); 88 auto *MBFI = (PSI && PSI->hasProfileSummary()) ? 89 &getAnalysis<LazyMachineBlockFrequencyInfoPass>().getBFI() : 90 nullptr; 91 Duplicator.initMF(MF, PreRegAlloc, MBPI, MBFI, PSI, /*LayoutMode=*/false); 92 93 bool MadeChange = false; 94 while (Duplicator.tailDuplicateBlocks()) 95 MadeChange = true; 96 97 return MadeChange; 98 } 99