Method DuplicateLoop

source/opt/loop_unroller.cpp:849–884

Uses the first loop to create a copy of the loop with new IDs.

// Uses the first loop to create a copy of the loop with new IDs.
bool LoopUnrollerUtilsImpl::DuplicateLoop(Loop* old_loop, Loop* new_loop) {
  std::vector<BasicBlock*> new_block_order;

  // Copy every block in the old loop.
  for (const BasicBlock* itr : loop_blocks_inorder_) {
    if (!CopyBasicBlock(old_loop, itr, true)) {
      return false;
    }
    new_block_order.push_back(blocks_to_add_.back().get());
  }

  // Clone the merge block, give it a new id and record it in the state.
  BasicBlock* new_merge = old_loop->GetMergeBlock()->Clone(context_);
  if (!new_merge) return false;
  new_merge->SetParent(old_loop->GetMergeBlock()->GetParent());
  if (!AssignNewResultIds(new_merge)) {
    return false;
  }
  state_.new_blocks[old_loop->GetMergeBlock()->id()] = new_merge;

  // Remap the operands of every instruction in the loop to point to the new
  // copies.
  for (auto& pair : state_.new_blocks) {
    RemapOperands(pair.second);
  }

  loop_blocks_inorder_ = std::move(new_block_order);

  AddBlocksToLoop(new_loop);

  new_loop->SetHeaderBlock(state_.new_header_block);
  new_loop->SetContinueBlock(state_.new_continue_block);
  new_loop->SetLatchBlock(state_.new_latch_block);
  new_loop->SetMergeBlock(new_merge);
  return true;
}

// Whenever the utility copies a block it stores it in a temporary buffer, this
// function adds the buffer into the Function. The blocks will be inserted