Method GetPeelingInfo

source/opt/loop_peeling.cpp:905–1031

}

LoopPeelingPass::LoopPeelingInfo::Direction
LoopPeelingPass::LoopPeelingInfo::GetPeelingInfo(BasicBlock* bb) const {
  if (bb->terminator()->opcode() != spv::Op::OpBranchConditional) {
    return GetNoneDirection();
  }

  analysis::DefUseManager* def_use_mgr = context_->get_def_use_mgr();

  Instruction* condition =
      def_use_mgr->GetDef(bb->terminator()->GetSingleWordInOperand(0));

  if (!IsHandledCondition(condition->opcode())) {
    return GetNoneDirection();
  }

  if (!GetFirstLoopInvariantOperand(condition)) {
    // No loop invariant, it cannot be peeled by this pass.
    return GetNoneDirection();
  }
  if (!GetFirstNonLoopInvariantOperand(condition)) {
    // Seems to be a job for the unswitch pass.
    return GetNoneDirection();
  }

  // Left hand-side.
  SExpression lhs = scev_analysis_->AnalyzeInstruction(
      def_use_mgr->GetDef(condition->GetSingleWordInOperand(0)));
  if (lhs->GetType() == SENode::CanNotCompute) {
    // Can't make any conclusion.
    return GetNoneDirection();
  }

  // Right hand-side.
  SExpression rhs = scev_analysis_->AnalyzeInstruction(
      def_use_mgr->GetDef(condition->GetSingleWordInOperand(1)));
  if (rhs->GetType() == SENode::CanNotCompute) {
    // Can't make any conclusion.
    return GetNoneDirection();
  }

  // Only take into account recurrent expression over the current loop.
  bool is_lhs_rec = !scev_analysis_->IsLoopInvariant(loop_, lhs);
  bool is_rhs_rec = !scev_analysis_->IsLoopInvariant(loop_, rhs);

  if ((is_lhs_rec && is_rhs_rec) || (!is_lhs_rec && !is_rhs_rec)) {
    return GetNoneDirection();
  }

  if (is_lhs_rec) {
    if (!lhs->AsSERecurrentNode() ||
        lhs->AsSERecurrentNode()->GetLoop() != loop_) {
      return GetNoneDirection();
    }
  }
  if (is_rhs_rec) {
    if (!rhs->AsSERecurrentNode() ||
        rhs->AsSERecurrentNode()->GetLoop() != loop_) {
      return GetNoneDirection();