Merge pull request #9247 from The-OpenROAD-Project-staging/mpl-tight-packing

mpl: enumerate tilings for macro clusters instead of using simulated annealing

Author: maliberty

src/mpl/src/clusterEngine.cpp

@@ -1227,8 +1227,7 @@ void ClusteringEngine::multilevelAutocluster(Cluster* parent)
   if (level_ == 0) {
     const int leaf_max_std_cell
         = tree_->base_max_std_cell
-          / std::pow(tree_->cluster_size_ratio, tree_->max_level - 1)
-          * (1 + size_tolerance_);
+          / std::pow(tree_->cluster_size_ratio, tree_->max_level - 1);
     if (parent->getNumStdCell() < leaf_max_std_cell) {
       force_split_root = true;
       debugPrint(logger_,
@@ -1293,13 +1292,6 @@ void ClusteringEngine::updateSizeThresholds()
   max_std_cell_ = tree_->base_max_std_cell / coarse_factor;
   min_std_cell_ = tree_->base_min_std_cell / coarse_factor;
 
-  // We define the tolerance to improve the robustness of our hierarchical
-  // clustering
-  max_macro_ *= (1 + size_tolerance_);
-  min_macro_ *= (1 - size_tolerance_);
-  max_std_cell_ *= (1 + size_tolerance_);
-  min_std_cell_ *= (1 - size_tolerance_);
-
   if (min_macro_ <= 0) {
     min_macro_ = 1;
     max_macro_ = min_macro_ * tree_->cluster_size_ratio / 2.0;

src/mpl/src/clusterEngine.h

@@ -309,7 +309,6 @@ class ClusteringEngine
   int min_macro_{0};
   int max_std_cell_{0};
   int min_std_cell_{0};
-  const float size_tolerance_ = 0.1;
 
   // Variables for data flow
   DataFlow data_connections_;

src/mpl/src/hier_rtlmp.cpp

@@ -635,240 +635,65 @@ void HierRTLMP::calculateMacroTilings(Cluster* cluster)
   }
 
   std::vector<HardMacro*> hard_macros = cluster->getHardMacros();
-  TilingSet tilings_set;
-
-  if (hard_macros.size() == 1) {
-    int width = hard_macros[0]->getWidth();
-    int height = hard_macros[0]->getHeight();
-
-    TilingList tilings;
-    tilings.emplace_back(width, height);
-    cluster->setTilings(tilings);
-
-    debugPrint(logger_,
-               MPL,
-               "coarse_shaping",
-               1,
-               "{} has only one macro, set tiling according to macro with halo",
-               cluster->getName());
-    return;
-  }
+  int number_of_macros = hard_macros.size();
+  int macro_width = hard_macros.front()->getWidth();
+  int macro_height = hard_macros.front()->getHeight();
 
-  if (cluster->isArrayOfInterconnectedMacros()) {
-    setTightPackingTilings(cluster);
-    return;
-  }
+  TilingList tilings = generateTilingsForMacroCluster(
+      macro_width, macro_height, number_of_macros);
 
-  if (graphics_) {
-    graphics_->setCurrentCluster(cluster);
-  }
-
-  // otherwise call simulated annealing to determine tilings
-  // set the action probabilities
-  const float action_sum = pos_swap_prob_ + neg_swap_prob_ + double_swap_prob_
-                           + exchange_swap_prob_;
-
-  const odb::Rect outline(
-      0, 0, tree_->root->getWidth(), tree_->root->getHeight());
-
-  // update macros
-  std::vector<HardMacro> macros;
-  macros.reserve(hard_macros.size());
-  for (auto& macro : hard_macros) {
-    macros.push_back(*macro);
-  }
-  int num_perturb_per_step = (macros.size() > num_perturb_per_step_ / 10)
-                                 ? macros.size()
-                                 : num_perturb_per_step_ / 10;
-  if (cluster->getParent() == nullptr) {
-    num_perturb_per_step = (macros.size() > num_perturb_per_step_ / 5)
-                               ? macros.size()
-                               : num_perturb_per_step_ / 5;
-  }
-
-  // To generate different macro tilings, we vary the outline constraints
-  // we first vary the outline width while keeping outline_height fixed
-  // Then we vary the outline height while keeping outline_width fixed
-  // We vary the outline of cluster to generate different tilings
-  std::vector<float> vary_factor_list{1.0};
-  float vary_step = 1.0 / num_runs_;  // change the outline by at most halfly
-  for (int i = 1; i < num_runs_; i++) {
-    vary_factor_list.push_back(1.0 - i * vary_step);
-  }
-  int remaining_runs = num_runs_;
-  int run_id = 0;
-  while (remaining_runs > 0) {
-    HardSAVector sa_batch;
-    const int run_thread
-        = graphics_ ? 1 : std::min(remaining_runs, num_threads_);
-    for (int i = 0; i < run_thread; i++) {
-      const odb::Rect new_outline(
-          0, 0, outline.dx() * vary_factor_list[run_id++], outline.dy());
-      if (graphics_) {
-        graphics_->setOutline(new_outline);
-      }
-      std::unique_ptr<SACoreHardMacro> sa
-          = std::make_unique<SACoreHardMacro>(tree_.get(),
-                                              new_outline,
-                                              macros,
-                                              shaping_core_weights_,
-                                              pos_swap_prob_ / action_sum,
-                                              neg_swap_prob_ / action_sum,
-                                              double_swap_prob_ / action_sum,
-                                              exchange_swap_prob_ / action_sum,
-                                              init_prob_,
-                                              max_num_step_,
-                                              num_perturb_per_step,
-                                              random_seed_ + run_id,
-                                              graphics_.get(),
-                                              logger_,
-                                              block_);
-      sa_batch.push_back(std::move(sa));
-    }
-    if (sa_batch.size() == 1) {
-      runSA<SACoreHardMacro>(sa_batch[0].get());
-    } else {
-      // multi threads
-      std::vector<std::thread> threads;
-      threads.reserve(sa_batch.size());
-      for (auto& sa : sa_batch) {
-        threads.emplace_back(runSA<SACoreHardMacro>, sa.get());
-      }
-      for (auto& th : threads) {
-        th.join();
-      }
-    }
-    // add macro tilings
-    for (auto& sa : sa_batch) {
-      if (sa->fitsIn(outline)) {
-        tilings_set.insert({sa->getWidth(), sa->getHeight()});
-      }
-    }
-    remaining_runs -= run_thread;
-  }
-  // change the outline height while keeping outline width fixed
-  remaining_runs = num_runs_;
-  run_id = 0;
-  while (remaining_runs > 0) {
-    HardSAVector sa_batch;
-    const int run_thread
-        = graphics_ ? 1 : std::min(remaining_runs, num_threads_);
-    for (int i = 0; i < run_thread; i++) {
-      const odb::Rect new_outline(
-          0, 0, outline.dx(), outline.dy() * vary_factor_list[run_id++]);
-      if (graphics_) {
-        graphics_->setOutline(new_outline);
-      }
-      std::unique_ptr<SACoreHardMacro> sa
-          = std::make_unique<SACoreHardMacro>(tree_.get(),
-                                              new_outline,
-                                              macros,
-                                              shaping_core_weights_,
-                                              pos_swap_prob_ / action_sum,
-                                              neg_swap_prob_ / action_sum,
-                                              double_swap_prob_ / action_sum,
-                                              exchange_swap_prob_ / action_sum,
-                                              init_prob_,
-                                              max_num_step_,
-                                              num_perturb_per_step,
-                                              random_seed_ + run_id,
-                                              graphics_.get(),
-                                              logger_,
-                                              block_);
-      sa_batch.push_back(std::move(sa));
-    }
-    if (sa_batch.size() == 1) {
-      runSA<SACoreHardMacro>(sa_batch[0].get());
-    } else {
-      // multi threads
-      std::vector<std::thread> threads;
-      threads.reserve(sa_batch.size());
-      for (auto& sa : sa_batch) {
-        threads.emplace_back(runSA<SACoreHardMacro>, sa.get());
-      }
-      for (auto& th : threads) {
-        th.join();
-      }
-    }
-    // add macro tilings
-    for (auto& sa : sa_batch) {
-      if (sa->fitsIn(outline)) {
-        tilings_set.insert({sa->getWidth(), sa->getHeight()});
-      }
-    }
-    remaining_runs -= run_thread;
+  if (tilings.empty()) {
+    tilings = generateTilingsForMacroCluster(
+        macro_width, macro_height, number_of_macros + 1);
   }
 
-  if (tilings_set.empty()) {
+  if (tilings.empty()) {
     logger_->error(MPL,
                    4,
-                   "No valid tilings for hard macro cluster: {}",
-                   cluster->getName());
+                   "Unable to fit cluster {} within outline. Macro height: {}, "
+                   "width: {}, number of macros: {}.",
+                   cluster->getName(),
+                   macro_width,
+                   macro_height,
+                   number_of_macros);
   }
 
-  TilingList tilings_list(tilings_set.begin(), tilings_set.end());
-  std::ranges::sort(tilings_list, isAreaSmaller);
+  cluster->setTilings(tilings);
 
-  for (auto& tiling : tilings_list) {
-    debugPrint(logger_,
-               MPL,
-               "coarse_shaping",
-               2,
-               "width: {}, height: {}",
-               tiling.width(),
-               tiling.height());
-  }
-
-  // we only keep the minimum area tiling since all the macros has the same size
-  // later this can be relaxed.  But this may cause problems because the
-  // minimizing the wirelength may leave holes near the boundary
-  TilingList new_tilings_list;
-  float first_tiling_area = tilings_list.front().area();
-  for (auto& tiling : tilings_list) {
-    if (tiling.area() <= first_tiling_area) {
-      new_tilings_list.push_back(tiling);
+  if (logger_->debugCheck(MPL, "coarse_shaping", 2)) {
+    std::string line = "Tiling for hard cluster " + cluster->getName()
+                       + " with " + std::to_string(number_of_macros)
+                       + " macros.\n";
+    for (auto& tiling : tilings) {
+      line += " < " + std::to_string(tiling.width()) + " , ";
+      line += std::to_string(tiling.height()) + " >  ";
     }
+    line += "\n";
+    debugPrint(logger_, MPL, "coarse_shaping", 2, "{}", line);
   }
-  tilings_list = std::move(new_tilings_list);
-  cluster->setTilings(tilings_list);
-
-  std::string line = "Tiling for hard cluster " + cluster->getName() + "  ";
-  for (auto& tiling : tilings_list) {
-    line += " < " + std::to_string(tiling.width()) + " , ";
-    line += std::to_string(tiling.height()) + " >  ";
-  }
-  line += "\n";
-  debugPrint(logger_, MPL, "coarse_shaping", 2, "{}", line);
 }
 
-// Used only for arrays of interconnected macros.
-void HierRTLMP::setTightPackingTilings(Cluster* macro_array)
+TilingList HierRTLMP::generateTilingsForMacroCluster(int macro_width,
+                                                     int macro_height,
+                                                     int number_of_macros)
 {
   TilingList tight_packing_tilings;
-
-  int num_macro = macro_array->getNumMacro();
-  float macro_width = macro_array->getHardMacros().front()->getWidth();
-  float macro_height = macro_array->getHardMacros().front()->getHeight();
-
   const odb::Rect outline = tree_->root->getBBox();
 
-  int columns = 0;
-  for (int rows = 1; rows < std::sqrt(num_macro) + 1; rows++) {
-    if (num_macro % rows == 0) {
-      columns = num_macro / rows;
+  int rows = 0;
+  for (int cols = 1; cols <= number_of_macros; cols++) {
+    if (number_of_macros % cols == 0) {
+      rows = number_of_macros / cols;
 
-      // We don't consider tilings for right angle rotation orientations,
-      // because they're not allowed in our macro placer.
-      // Tiling needs to fit inside outline
-      if (columns * macro_width <= outline.dx()
+      if (cols * macro_width <= outline.dx()
           && rows * macro_height <= outline.dy()) {
-        tight_packing_tilings.emplace_back(columns * macro_width,
+        tight_packing_tilings.emplace_back(cols * macro_width,
                                            rows * macro_height);
       }
     }
   }
 
-  macro_array->setTilings(tight_packing_tilings);
+  return tight_packing_tilings;
 }
 
 void HierRTLMP::searchAvailableRegionsForUnconstrainedPins()

src/mpl/src/hier_rtlmp.h

@@ -145,7 +145,9 @@ class HierRTLMP
   void calculateChildrenTilings(Cluster* parent);
   void calculateMacroTilings(Cluster* cluster);
   IntervalList computeWidthIntervals(const TilingList& tilings);
-  void setTightPackingTilings(Cluster* macro_array);
+  TilingList generateTilingsForMacroCluster(int macro_width,
+                                            int macro_height,
+                                            int number_of_macros);
   void searchAvailableRegionsForUnconstrainedPins();
   BoundaryToRegionsMap getBoundaryToBlockedRegionsMap(
       const std::vector<odb::Rect>& blocked_regions_for_pins) const;