Method AreCompatible

source/opt/loop_fusion.cpp:108–231

}

bool LoopFusion::AreCompatible() {
  // Check that the loops are in the same function.
  if (loop_0_->GetHeaderBlock()->GetParent() !=
      loop_1_->GetHeaderBlock()->GetParent()) {
    return false;
  }

  // Check that both loops have pre-header blocks.
  if (!loop_0_->GetPreHeaderBlock() || !loop_1_->GetPreHeaderBlock()) {
    return false;
  }

  // Check there are no breaks.
  if (context_->cfg()->preds(loop_0_->GetMergeBlock()->id()).size() != 1 ||
      context_->cfg()->preds(loop_1_->GetMergeBlock()->id()).size() != 1) {
    return false;
  }

  // Check there are no continues.
  if (context_->cfg()->preds(loop_0_->GetContinueBlock()->id()).size() != 1 ||
      context_->cfg()->preds(loop_1_->GetContinueBlock()->id()).size() != 1) {
    return false;
  }

  // |GetInductionVariables| returns all OpPhi in the header. Check that both
  // loops have exactly one that is used in the continue and condition blocks.
  std::vector<Instruction*> inductions_0{}, inductions_1{};
  loop_0_->GetInductionVariables(inductions_0);
  RemoveIfNotUsedContinueOrConditionBlock(&inductions_0, loop_0_);

  if (inductions_0.size() != 1) {
    return false;
  }

  induction_0_ = inductions_0.front();

  loop_1_->GetInductionVariables(inductions_1);
  RemoveIfNotUsedContinueOrConditionBlock(&inductions_1, loop_1_);

  if (inductions_1.size() != 1) {
    return false;
  }

  induction_1_ = inductions_1.front();

  if (!CheckInit()) {
    return false;
  }

  if (!CheckCondition()) {
    return false;
  }

  if (!CheckStep()) {
    return false;
  }

  // Check adjacency, |loop_0_| should come just before |loop_1_|.