Method splitEdge

source/opt/invocation_interlock_placement_pass.cpp:294–330

}

BasicBlock* InvocationInterlockPlacementPass::splitEdge(BasicBlock* block,
                                                        uint32_t succ_id) {
  // Create a new block to replace the critical edge.
  uint32_t new_id = context()->TakeNextId();
  if (new_id == 0) {
    return nullptr;
  }
  auto new_succ_temp = MakeUnique<BasicBlock>(
      MakeUnique<Instruction>(context(), spv::Op::OpLabel, 0, new_id,
                              std::initializer_list<Operand>{}));
  auto* new_succ = new_succ_temp.get();

  // Insert the new block into the function.
  block->GetParent()->InsertBasicBlockAfter(std::move(new_succ_temp), block);

  new_succ->AddInstruction(MakeUnique<Instruction>(
      context(), spv::Op::OpBranch, 0, 0,
      std::initializer_list<Operand>{
          Operand(spv_operand_type_t::SPV_OPERAND_TYPE_ID, {succ_id})}));

  assert(block->tail()->opcode() == spv::Op::OpBranchConditional ||
         block->tail()->opcode() == spv::Op::OpSwitch);

  // Update the first branch to successor to instead branch to
  // the new successor. If there are multiple edges, we arbitrarily choose the
  // first time it appears in the list. The other edges to `succ_id` will have
  // to be split by another call to `splitEdge`.
  block->tail()->WhileEachInId([new_succ, succ_id](uint32_t* branch_id) {
    if (*branch_id == succ_id) {
      *branch_id = new_succ->id();
      return false;
    }
    return true;
  });

  return new_succ;
}

Pass::Status InvocationInterlockPlacementPass::placeInstructionsForEdge(
    BasicBlock* block, uint32_t next_id, BlockSet& inside,