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/CodeGen/MachineBranchProbabilityInfo.h" 16 #include "llvm/CodeGen/MachineFunction.h" 17 #include "llvm/CodeGen/MachineFunctionPass.h" 18 #include "llvm/CodeGen/MachineRegisterInfo.h" 19 #include "llvm/CodeGen/Passes.h" 20 #include "llvm/CodeGen/TailDuplicator.h" 21 #include "llvm/InitializePasses.h" 22 #include "llvm/Pass.h" 23 24 using namespace llvm; 25 26 #define DEBUG_TYPE "tailduplication" 27 28 namespace { 29 30 class TailDuplicateBase : public MachineFunctionPass { 31 TailDuplicator Duplicator; 32 bool PreRegAlloc; 33 public: 34 TailDuplicateBase(char &PassID, bool PreRegAlloc) 35 : MachineFunctionPass(PassID), PreRegAlloc(PreRegAlloc) {} 36 37 bool runOnMachineFunction(MachineFunction &MF) override; 38 39 void getAnalysisUsage(AnalysisUsage &AU) const override { 40 AU.addRequired<MachineBranchProbabilityInfo>(); 41 MachineFunctionPass::getAnalysisUsage(AU); 42 } 43 }; 44 45 class TailDuplicate : public TailDuplicateBase { 46 public: 47 static char ID; 48 TailDuplicate() : TailDuplicateBase(ID, false) { 49 initializeTailDuplicatePass(*PassRegistry::getPassRegistry()); 50 } 51 }; 52 53 class EarlyTailDuplicate : public TailDuplicateBase { 54 public: 55 static char ID; 56 EarlyTailDuplicate() : TailDuplicateBase(ID, true) { 57 initializeEarlyTailDuplicatePass(*PassRegistry::getPassRegistry()); 58 } 59 }; 60 61 } // end anonymous namespace 62 63 char TailDuplicate::ID; 64 char EarlyTailDuplicate::ID; 65 66 char &llvm::TailDuplicateID = TailDuplicate::ID; 67 char &llvm::EarlyTailDuplicateID = EarlyTailDuplicate::ID; 68 69 INITIALIZE_PASS(TailDuplicate, DEBUG_TYPE, "Tail Duplication", false, false) 70 INITIALIZE_PASS(EarlyTailDuplicate, "early-tailduplication", 71 "Early Tail Duplication", false, false) 72 73 bool TailDuplicateBase::runOnMachineFunction(MachineFunction &MF) { 74 if (skipFunction(MF.getFunction())) 75 return false; 76 77 auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>(); 78 Duplicator.initMF(MF, PreRegAlloc, MBPI, /*LayoutMode=*/false); 79 80 bool MadeChange = false; 81 while (Duplicator.tailDuplicateBlocks()) 82 MadeChange = true; 83 84 return MadeChange; 85 } 86