1 //===- TailDuplication.cpp - Duplicate blocks into predecessors' tails ----===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This pass duplicates basic blocks ending in unconditional branches into 11 // the tails of their predecessors, using the TailDuplicator utility 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/TailDuplicator.h" 19 #include "llvm/Pass.h" 20 21 using namespace llvm; 22 23 #define DEBUG_TYPE "tailduplication" 24 25 namespace { 26 27 /// Perform tail duplication. Delegates to TailDuplicator 28 class TailDuplicatePass : public MachineFunctionPass { 29 TailDuplicator Duplicator; 30 31 public: 32 static char ID; 33 34 explicit TailDuplicatePass() : MachineFunctionPass(ID) {} 35 36 bool runOnMachineFunction(MachineFunction &MF) override; 37 38 void getAnalysisUsage(AnalysisUsage &AU) const override; 39 }; 40 41 } // end anonymous namespace 42 43 char TailDuplicatePass::ID = 0; 44 45 char &llvm::TailDuplicateID = TailDuplicatePass::ID; 46 47 INITIALIZE_PASS(TailDuplicatePass, DEBUG_TYPE, "Tail Duplication", false, false) 48 49 bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) { 50 if (skipFunction(*MF.getFunction())) 51 return false; 52 53 auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>(); 54 55 Duplicator.initMF(MF, MBPI, /* LayoutMode */ false); 56 57 bool MadeChange = false; 58 while (Duplicator.tailDuplicateBlocks()) 59 MadeChange = true; 60 61 return MadeChange; 62 } 63 64 void TailDuplicatePass::getAnalysisUsage(AnalysisUsage &AU) const { 65 AU.addRequired<MachineBranchProbabilityInfo>(); 66 MachineFunctionPass::getAnalysisUsage(AU); 67 } 68