odb:: Error when the dbNet is connected with an dbInstance in the another dbBlock

[ApeachM]

Hi. I want to report an error with odb. If a net is connected with a dbIterm which is in another block, then something happens in an unexpected way.

This is the test code.

You can reproduce this error with this commit.

#include <iostream>

#include "db.h"
#include "defin.h"
#include "lefin.h"
#include "lefout.h"

using namespace odb;  // NOLINT(*-build-using-namespace)
using namespace std;  // NOLINT(*-build-using-namespace)
int main()
{
  dbDatabase* db_database = dbDatabase::create();
  dbTech* tech1 = dbTech::create(db_database, "top_tech");
  dbTech* tech2 = dbTech::create(db_database, "bottom_tech");
  auto* layer1
      = dbTechLayer::create(tech1, "top_layer", dbTechLayerType::MASTERSLICE);
  auto* layer2
      = dbTechLayer::create(tech2, "bottom_layer", dbTechLayerType::ROUTING);
  dbLib* lib1 = dbLib::create(db_database, "top_lib", tech1);
  dbLib* lib2 = dbLib::create(db_database, "bottom_lib", tech2);
  dbChip* chip = dbChip::create(db_database);
  dbBlock* block1 = dbBlock::create(chip, "top", tech1);
  dbBlock* block2 = dbBlock::create(block1, "bottom", tech2);
  // die size setting
  Rect die_rect(0, 0, 1000, 1000);
  block1->setDieArea(die_rect);
  block2->setDieArea(die_rect);

  vector<dbInst*> inst_collector_top;
  vector<dbInst*> inst_collector_bottom;

  // Example Library cell construction - top
  int top_lib_cell_num = 3;
  for (int i = 0; i < top_lib_cell_num; ++i) {
    int width = 100 + i * 10;
    int height = 200;
    dbMaster* master
        = dbMaster::create(lib1, ("top_cell_" + to_string(i)).c_str());
    master->setWidth(width);
    master->setHeight(height);
    master->setType(dbMasterType::CORE);

    int pin_num = 2 + i;
    for (int j = 0; j < pin_num; ++j) {
      dbSigType sig_type = dbSigType::SIGNAL;
      dbIoType io_type;
      if (j < pin_num - 1)
        io_type = dbIoType::INPUT;
      else
        io_type = dbIoType::OUTPUT;
      string pin_name = "top_pin_" + to_string(j);
      dbMTerm* master_terminal
          = dbMTerm::create(master, pin_name.c_str(), io_type, sig_type);
      dbMPin* master_pin = dbMPin::create(master_terminal);
      dbBox::create(master_pin, layer1, j * 2, j * 2, j * 2 + 1, j * 2 + 1);
    }
    master->setFrozen();
  }

  // Example Instance cells for top
  int instance_num = 10;
  // pick random number between 0 and top_lib_cell_num - 1, with fixed seed.
  srand(0);  // NOLINT(*-msc51-cpp)
  for (int i = 0; i < instance_num; ++i) {
    int lib_cell_id = rand() % top_lib_cell_num;  // NOLINT(*-msc50-cpp)
    int x, y;
    // set the x and y coordinate of the instance in the die area randomly.
    x = rand() % 1000;  // NOLINT(*-msc50-cpp)
    y = rand() % 1000;  // NOLINT(*-msc50-cpp)
    string inst_name = "top_inst_" + to_string(i);
    dbMaster* master = db_database->findMaster(
        ("top_cell_" + to_string(lib_cell_id)).c_str());
    auto inst = dbInst::create(block1, master, inst_name.c_str());
    inst->setLocation(x, y);
    inst_collector_top.push_back(inst);
  }

  // Example Library cell construction - bottom
  int bottom_lib_cell_num = 4;
  for (int i = 0; i < bottom_lib_cell_num; ++i) {
    int width = 200 + i * 20;
    int height = 300;
    dbMaster* master
        = dbMaster::create(lib2, ("bottom_cell_" + to_string(i)).c_str());
    master->setWidth(width);
    master->setHeight(height);
    master->setType(dbMasterType::CORE);

    int pin_num = 3 + i;
    for (int j = 0; j < pin_num; ++j) {
      dbSigType sig_type = dbSigType::SIGNAL;
      dbIoType io_type;
      if (j < pin_num - 1)
        io_type = dbIoType::INPUT;
      else
        io_type = dbIoType::OUTPUT;
      string pin_name = "bottom_pin_" + to_string(j);
      dbMTerm* master_terminal
          = dbMTerm::create(master, pin_name.c_str(), io_type, sig_type);
      dbMPin* master_pin = dbMPin::create(master_terminal);
      dbBox::create(master_pin, layer2, j * 2, j * 2, j * 2 + 1, j * 2 + 1);
    }
    master->setFrozen();
  }

  // Example Instance cells for bottom
  for (int i = 0; i < instance_num; ++i) {
    int lib_cell_id = rand() % top_lib_cell_num;  // NOLINT(*-msc50-cpp)
    int x, y;
    // set the x and y coordinate of the instance in the die area randomly.
    x = rand() % 1000;  // NOLINT(*-msc50-cpp)
    y = rand() % 1000;  // NOLINT(*-msc50-cpp)
    string inst_name = "bottom_inst_" + to_string(i);
    dbMaster* master = db_database->findMaster(
        ("bottom_cell_" + to_string(lib_cell_id)).c_str());
    auto inst = dbInst::create(block2, master, inst_name.c_str());
    inst->setLocation(x, y);
    inst_collector_bottom.push_back(inst);
  }

  int inst_id1 = 5;
  int inst_id2 = 4;

  // intersected net test
  dbNet* net = dbNet::create(block1, ("net_" + to_string(inst_id1)).c_str());
  dbInst* inst1_top = inst_collector_top.at(inst_id1);
  dbInst* inst2_top = inst_collector_top.at(inst_id2);
  dbInst* inst1_bottom = inst_collector_bottom.at(inst_id1);
  dbITerm* i_term_top1 = inst1_top->findITerm("top_pin_0");
  dbITerm* i_term_top2 = inst2_top->findITerm("top_pin_0");
  dbITerm* i_term_bottom = inst1_bottom->findITerm("bottom_pin_0");
  i_term_top1->connect(net);
  i_term_top2->connect(net);
  i_term_bottom->connect(net);

  cout << "inst1_top: " << inst1_top->getName() << '\n';
  cout << "inst2_top: " << inst2_top->getName() << '\n';
  cout << "inst1_bottom: " << inst1_bottom->getName() << '\n' << '\n';

  cout << "connected instance number: " << net->getITermCount() << '\n';
  for (auto i_term : net->getITerms()) {
    cout << i_term->getInst()->getName() << '\n';
  }

  /**
   * Console result:
   * \code
      inst1_top: top_inst_5
      inst2_top: top_inst_4
      inst1_bottom: bottom_inst_5

      connected instance number: 1
      top_inst_6
   * */
}

The expected result should be below,

inst1_top: top_inst_5
inst2_top: top_inst_4
inst1_bottom: bottom_inst_5

connected instance number: 3
top_inst_5
top_inst_4
bottom_inst_5

but the console result is here.

inst1_top: top_inst_5
inst2_top: top_inst_4
inst1_bottom: bottom_inst_5

connected instance number: 1
top_inst_6

If I erase the line of code below, then it seems to work well in the right way.

  // i_term_bottom->connect(net);

[maliberty]

That's not supported. In general the multi-block connectivity model still needs work. The usage will be to have a dbBTerm on each block and at the top level to connect the corresponding dbITerms. You can't connect laterally across the hierarchy (same as Verilog).

[ApeachM]

Thank you for replying.
I suggest making an exception if there's any try like the above when you afford to do it.
I would send a pull-request like below, but I think it cost quite big complexity.

void dbITerm::connect(dbNet* net_)
{
  _dbITerm* iterm = (_dbITerm*) this;
  _dbNet* net = (_dbNet*) net_;
  _dbBlock* block = (_dbBlock*) iterm->getOwner();

  // Do Nothing if already connected
  if (iterm->_net == net->getOID())
    return;

  _dbInst* inst = iterm->getInst();
  if (inst->_flags._dont_touch) {
    inst->getLogger()->error(
        utl::ODB,
        369,
        "Attempt to connect iterm of dont_touch instance {}",
        inst->_name);
  }

  if (net->_flags._dont_touch) {
    inst->getLogger()->error(utl::ODB,
                             373,
                             "Attempt to connect iterm to dont_touch net {}",
                             net->_name);
  }
///////////////////////////// Edited part /////////////////////////////
  for (auto otherIterm_ : net_->getITerms()) {
    _dbBlock* otherBlock = (_dbBlock*) otherIterm_->getBlock();
    if (block != otherBlock)
      inst->getLogger()->error(utl::ODB,
                               433,
                               "Connecting instances on different dies into "
                               "one net is currently not supported");
  }
///////////////////////////////////////////////////////////////////////
  if (iterm->_net != 0)
    disconnect();

  for (auto callback : block->_callbacks)
    callback->inDbITermPreConnect(this, net_);

  if (block->_journal) {
    debugPrint(iterm->getImpl()->getLogger(),
               utl::ODB,
               "DB_ECO",
               1,
               "ECO: connect Iterm {} to net {}",
               getId(),
               net_->getId());
    block->_journal->beginAction(dbJournal::CONNECT_OBJECT);
    block->_journal->pushParam(dbITermObj);
    block->_journal->pushParam(getId());
    block->_journal->pushParam(net_->getId());
    block->_journal->endAction();
  }

  iterm->_net = net->getOID();

  if (net->_iterms != 0) {
    _dbITerm* tail = block->_iterm_tbl->getPtr(net->_iterms);
    iterm->_next_net_iterm = net->_iterms;
    iterm->_prev_net_iterm = 0;
    tail->_prev_net_iterm = iterm->getOID();
  } else {
    iterm->_next_net_iterm = 0;
    iterm->_prev_net_iterm = 0;
  }

  net->_iterms = iterm->getOID();

  for (auto callback : block->_callbacks)
    callback->inDbITermPostConnect(this);
}

Maybe a variable in _dbNet is required to indicate the die in which this net belongs.

Thank you!

p.s.
I'd like to inquire about when the ODB version that allows binding instances on different dies into one net will be supported. If it takes a considerable amount of time, I'm wondering if my participation in updating the ODB version would be helpful or meaningful.

[maliberty]

There is no need to iterate - you can ask the dbNet what block it is in with getBlock()