1 //===-- TailDuplication.cpp - Duplicate blocks into predecessors' tails ---===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass duplicates basic blocks ending in unconditional branches into
11 // the tails of their predecessors, using the TailDuplicator utility class.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/CodeGen/MachineFunctionPass.h"
16 #include "llvm/CodeGen/Passes.h"
17 #include "llvm/CodeGen/TailDuplicator.h"
18 #include "llvm/IR/Function.h"
19 #include "llvm/Support/Debug.h"
22 #define DEBUG_TYPE "tailduplication"
25 /// Perform tail duplication. Delegates to TailDuplicator
26 class TailDuplicatePass : public MachineFunctionPass {
27 TailDuplicator Duplicator;
31 explicit TailDuplicatePass() : MachineFunctionPass(ID) {}
33 bool runOnMachineFunction(MachineFunction &MF) override;
35 void getAnalysisUsage(AnalysisUsage &AU) const override;
38 char TailDuplicatePass::ID = 0;
41 char &llvm::TailDuplicateID = TailDuplicatePass::ID;
43 INITIALIZE_PASS(TailDuplicatePass, "tailduplication", "Tail Duplication", false,
46 bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
47 if (skipFunction(*MF.getFunction()))
50 auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
52 Duplicator.initMF(MF, MBPI, /* LayoutMode */ false);
54 bool MadeChange = false;
55 while (Duplicator.tailDuplicateBlocks())
61 void TailDuplicatePass::getAnalysisUsage(AnalysisUsage &AU) const {
62 AU.addRequired<MachineBranchProbabilityInfo>();
63 MachineFunctionPass::getAnalysisUsage(AU);