Method CopyBody

source/opt/loop_unroller.cpp:702–766

}

bool LoopUnrollerUtilsImpl::CopyBody(Loop* loop, bool eliminate_conditions) {
  // Copy each basic block in the loop, give them new ids, and save state
  // information.
  for (const BasicBlock* itr : loop_blocks_inorder_) {
    if (!CopyBasicBlock(loop, itr, false)) {
      return false;
    }
  }

  // Set the previous latch block to point to the new header.
  Instruction* latch_branch = state_.previous_latch_block_->terminator();
  latch_branch->SetInOperand(0, {state_.new_header_block->id()});
  context_->UpdateDefUse(latch_branch);

  // As the algorithm copies the original loop blocks exactly, the tail of the
  // latch block on iterations after the first one will be a branch to the new
  // header and not the actual loop header. The last continue block in the loop
  // should always be a backedge to the global header.
  Instruction* new_latch_branch = state_.new_latch_block->terminator();
  new_latch_branch->SetInOperand(0, {loop->GetHeaderBlock()->id()});
  context_->AnalyzeUses(new_latch_branch);

  std::vector<Instruction*> inductions;
  loop->GetInductionVariables(inductions);
  for (size_t index = 0; index < inductions.size(); ++index) {
    Instruction* primary_copy = inductions[index];

    assert(primary_copy->result_id() != 0);
    Instruction* induction_clone =
        state_.ids_to_new_inst[state_.new_inst[primary_copy->result_id()]];

    state_.new_phis_.push_back(induction_clone);
    assert(induction_clone->result_id() != 0);

    if (!state_.previous_phis_.empty()) {
      state_.new_inst[primary_copy->result_id()] = GetPhiDefID(
          state_.previous_phis_[index], state_.previous_latch_block_->id());
    } else {
      // Do not replace the first phi block ids.
      state_.new_inst[primary_copy->result_id()] = primary_copy->result_id();
    }
  }

  if (eliminate_conditions &&
      state_.new_condition_block != loop_condition_block_) {
    if (!FoldConditionBlock(state_.new_condition_block, 1)) {
      return false;
    }
  }

  // Only reference to the header block is the backedge in the latch block,
  // don't change this.
  state_.new_inst[loop->GetHeaderBlock()->id()] = loop->GetHeaderBlock()->id();

  for (auto& pair : state_.new_blocks) {
    RemapOperands(pair.second);
  }