Merge pull request #8851 from gadfort/pdn-bterms

pdn: add handling of fixed bpins in power grids

Author: maliberty

src/pdn/src/PdnGen.cc

@@ -71,8 +71,15 @@ void PdnGen::buildGrids(bool trim)
     insts_in_grids.insert(insts_in_grid.begin(), insts_in_grid.end());
   }
 
+  std::set<odb::dbNet*> grid_nets;
+  for (auto* grid : grids) {
+    const auto nets = grid->getNets();
+    grid_nets.insert(nets.begin(), nets.end());
+  }
+
   ShapeVectorMap block_obs_vec;
-  Grid::makeInitialObstructions(block, block_obs_vec, insts_in_grids, logger_);
+  Grid::makeInitialObstructions(
+      block, block_obs_vec, insts_in_grids, grid_nets, logger_);
   for (auto* grid : grids) {
     grid->getGridLevelObstructions(block_obs_vec);
   }

src/pdn/src/grid.cpp

@@ -1087,6 +1087,7 @@ void Grid::getGridLevelObstructions(ShapeVectorMap& obstructions) const
 void Grid::makeInitialObstructions(odb::dbBlock* block,
                                    ShapeVectorMap& obs,
                                    const std::set<odb::dbInst*>& skip_insts,
+                                   const std::set<odb::dbNet*>& skip_nets,
                                    utl::Logger* logger)
 {
   debugPrint(logger, utl::PDN, "Make", 2, "Get initial obstructions - begin");
@@ -1157,6 +1158,11 @@ void Grid::makeInitialObstructions(odb::dbBlock* block,
 
   // fixed pins obs
   for (auto* bterm : block->getBTerms()) {
+    if (skip_nets.find(bterm->getNet()) != skip_nets.end()) {
+      // these shapes will be collected as existing to the grid.
+      continue;
+    }
+
     for (auto* bpin : bterm->getBPins()) {
       if (!bpin->getPlacementStatus().isFixed()) {
         continue;

src/pdn/src/grid.h

@@ -146,6 +146,7 @@ class Grid
   static void makeInitialObstructions(odb::dbBlock* block,
                                       ShapeVectorMap& obs,
                                       const std::set<odb::dbInst*>& skip_insts,
+                                      const std::set<odb::dbNet*>& skip_nets,
                                       utl::Logger* logger);
   static void makeInitialShapes(odb::dbBlock* block,
                                 ShapeVectorMap& shapes,

src/pdn/src/renderer.cpp

@@ -60,7 +60,7 @@ void PDNRenderer::update()
     auto* domain = pdn_->getDomains()[0];
     ShapeVectorMap initial_shapes;
     Grid::makeInitialObstructions(
-        domain->getBlock(), initial_shapes, {}, domain->getLogger());
+        domain->getBlock(), initial_shapes, {}, {}, domain->getLogger());
     initial_obstructions_
         = Shape::convertVectorToObstructionTree(initial_shapes);
   }

src/pdn/src/shape.cpp

@@ -242,9 +242,25 @@ bool Shape::cut(const ObstructionTree& obstructions,
        it != obstructions.qend();
        it++) {
     const auto& other_shape = *it;
+
+    if (other_shape->net_ != nullptr && net_ == other_shape->net_) {
+      // obstruction is of the same net, so see if the violation is completely
+      // inside the new strap and therefore is okay
+      if (is_horizontal) {
+        if (rect_.yMin() <= other_shape->rect_.yMin()
+            && rect_.yMax() >= other_shape->rect_.yMax()) {
+          continue;
+        }
+      } else {
+        if (rect_.xMin() <= other_shape->rect_.xMin()
+            && rect_.xMax() >= other_shape->rect_.xMax()) {
+          continue;
+        }
+      }
+    }
+
     odb::Rect vio_rect
         = other_shape->getRectWithLargestObstructionHalo(obs_halo);
-
     // ensure the violation overlap fully with the shape to make cut correctly
     if (is_horizontal) {
       vio_rect.set_ylo(std::min(obs_.yMin(), vio_rect.yMin()));
@@ -451,6 +467,33 @@ odb::dbBox* Shape::addBPinToDb(const odb::Rect& rect) const
 
 void Shape::populateMapFromDb(odb::dbNet* net, ShapeVectorMap& map)
 {
+  // collect fixed bterms
+  for (auto* bterm : net->getBTerms()) {
+    for (auto* bpin : bterm->getBPins()) {
+      if (!bpin->getPlacementStatus().isFixed()) {
+        continue;
+      }
+      for (auto* box : bpin->getBoxes()) {
+        auto* layer = box->getTechLayer();
+        if (layer == nullptr) {
+          continue;
+        }
+        if (layer->getRoutingLevel() == 0) {
+          continue;
+        }
+
+        odb::Rect rect = box->getBox();
+
+        ShapePtr shape = std::make_shared<Shape>(
+            layer, net, rect, odb::dbWireShapeType::NONE);
+        shape->setShapeType(Shape::FIXED);
+        shape->generateObstruction();
+        map[layer].push_back(std::move(shape));
+      }
+    }
+  }
+
+  // collect existing routing
   for (auto* swire : net->getSWires()) {
     for (auto* box : swire->getWires()) {
       auto* layer = box->getTechLayer();

src/pdn/test/BUILD

@@ -50,6 +50,7 @@ COMPULSORY_TESTS = [
     "core_grid_via_snap",
     "core_grid_with_M6_min_area",
     "core_grid_with_M7_pins",
+    "core_grid_with_bterms",
     "core_grid_with_dual_rings",
     "core_grid_with_fixed_pins",
     "core_grid_with_m2_straps",

src/pdn/test/CMakeLists.txt

@@ -47,6 +47,7 @@ or_integration_tests(
     core_grid_via_snap
     core_grid_with_M6_min_area
     core_grid_with_M7_pins
+    core_grid_with_bterms
     core_grid_with_dual_rings
     core_grid_with_fixed_pins
     core_grid_with_m2_straps