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 | //===-- TailDuplication.cpp - Duplicate blocks into predecessors' tails ---===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass duplicates basic blocks ending in unconditional branches into
// the tails of their predecessors, using the TailDuplicator utility class.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TailDuplicator.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
#define DEBUG_TYPE "tailduplication"
namespace {
/// Perform tail duplication. Delegates to TailDuplicator
class TailDuplicatePass : public MachineFunctionPass {
  TailDuplicator Duplicator;
public:
  static char ID;
  explicit TailDuplicatePass() : MachineFunctionPass(ID) {}
  bool runOnMachineFunction(MachineFunction &MF) override;
  void getAnalysisUsage(AnalysisUsage &AU) const override;
};
char TailDuplicatePass::ID = 0;
}
char &llvm::TailDuplicateID = TailDuplicatePass::ID;
INITIALIZE_PASS(TailDuplicatePass, "tailduplication", "Tail Duplication", false,
                false)
bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
  if (skipFunction(*MF.getFunction()))
    return false;
  auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
  Duplicator.initMF(MF, MBPI, /* LayoutMode */ false);
  bool MadeChange = false;
  while (Duplicator.tailDuplicateBlocks())
    MadeChange = true;
  return MadeChange;
}
void TailDuplicatePass::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.addRequired<MachineBranchProbabilityInfo>();
  MachineFunctionPass::getAnalysisUsage(AU);
}
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