Method FixExitCondition

source/opt/loop_peeling.cpp:327–365

}

bool LoopPeeling::FixExitCondition(
    const std::function<uint32_t(Instruction*)>& condition_builder) {
  CFG& cfg = *context_->cfg();

  uint32_t condition_block_id = 0;
  for (uint32_t id : cfg.preds(GetClonedLoop()->GetMergeBlock()->id())) {
    if (GetClonedLoop()->IsInsideLoop(id)) {
      condition_block_id = id;
      break;
    }
  }
  assert(condition_block_id != 0 && "2nd loop in improperly connected");

  BasicBlock* condition_block = cfg.block(condition_block_id);
  Instruction* exit_condition = condition_block->terminator();
  assert(exit_condition->opcode() == spv::Op::OpBranchConditional);
  BasicBlock::iterator insert_point = condition_block->tail();
  if (condition_block->GetMergeInst()) {
    --insert_point;
  }

  uint32_t new_cond_id = condition_builder(&*insert_point);
  if (new_cond_id == 0) {
    return false;
  }
  exit_condition->SetInOperand(0, {new_cond_id});

  uint32_t to_continue_block_idx =
      GetClonedLoop()->IsInsideLoop(exit_condition->GetSingleWordInOperand(1))
          ? 1
          : 2;
  exit_condition->SetInOperand(
      1, {exit_condition->GetSingleWordInOperand(to_continue_block_idx)});
  exit_condition->SetInOperand(2, {GetClonedLoop()->GetMergeBlock()->id()});

  // Update def/use manager.
  context_->get_def_use_mgr()->AnalyzeInstUse(exit_condition);
  return true;
}

BasicBlock* LoopPeeling::CreateBlockBefore(BasicBlock* bb) {
  analysis::DefUseManager* def_use_mgr = context_->get_def_use_mgr();