Merge pull request #10842 from The-OpenROAD-Project-staging/cts_improve_level_creating_threshold

Cts: improve level creating threshold

Author: maliberty

src/cts/src/HTreeBuilder.cpp

@@ -1268,12 +1268,29 @@ void HTreeBuilder::run()
     computeLevelTopology(level, regionWidth, regionHeight);
 
     if (isNumberOfSinksTooSmall(numSinksPerSubRegion)) {
-      logger_->info(CTS,
-                    32,
-                    " Stop criterion found. Max number of sinks is {}.",
-                    options_->getMaxFanout() ? options_->getMaxFanout()
-                                             : numMaxLeafSinks_);
-      break;
+      if (options_->getMaxWl()) {
+        double maxHPWL = topologyForEachLevel_.back().getLargestSinkRegionHPWL(
+            wireSegmentUnit_);
+        if (maxHPWL < options_->getMaxWl()) {
+          logger_->info(CTS,
+                        38,
+                        " Stop criterion found. Sink region hpwl "
+                        "is smaller than max wirelength ({:.3f} um) and max "
+                        "number of sinks is {}.",
+                        static_cast<double>(options_->getMaxWl())
+                            / options_->getDbUnits(),
+                        options_->getMaxFanout() ? options_->getMaxFanout()
+                                                 : numMaxLeafSinks_);
+          break;
+        }
+      } else {
+        logger_->info(CTS,
+                      32,
+                      " Stop criterion found. Max number of sinks is {}.",
+                      options_->getMaxFanout() ? options_->getMaxFanout()
+                                               : numMaxLeafSinks_);
+        break;
+      }
     }
   }
 
@@ -1825,6 +1842,33 @@ void HTreeBuilder::initSecondLevelSinks(
   }
 }
 
+double HTreeBuilder::LevelTopology::getLargestSinkRegionHPWL(
+    const unsigned wireSegmentUnit) const
+{
+  double bestHpwl = 0.0;
+  for (unsigned i = 0; i < branchSinkLocs_.size(); ++i) {
+    const auto& sinks = branchSinkLocs_[i];
+    if (sinks.size() < 2) {
+      continue;
+    }
+    double minX = sinks[0].getX();
+    double maxX = minX;
+    double minY = sinks[0].getY();
+    double maxY = minY;
+    for (unsigned j = 1; j < sinks.size(); ++j) {
+      minX = std::min(minX, sinks[j].getX());
+      maxX = std::max(maxX, sinks[j].getX());
+      minY = std::min(minY, sinks[j].getY());
+      maxY = std::max(maxY, sinks[j].getY());
+    }
+    const double hpwl = ((maxX - minX) + (maxY - minY));
+    if (hpwl > bestHpwl) {
+      bestHpwl = hpwl;
+    }
+  }
+  return bestHpwl * wireSegmentUnit;
+}
+
 void HTreeBuilder::computeBranchSinks(
     const LevelTopology& topology,
     const unsigned branchIdx,

src/cts/src/HTreeBuilder.h

@@ -128,6 +128,8 @@ class HTreeBuilder : public TreeBuilder
       return branchSinkLocs_[branchIdx];
     }
 
+    double getLargestSinkRegionHPWL(unsigned wireSegmentUnit) const;
+
     void setOutputSlew(unsigned slew) { outputSlew_ = slew; }
     unsigned getOutputSlew() const { return outputSlew_; }
     void setOutputCap(unsigned cap) { outputCap_ = cap; }

src/cts/src/TritonCTS.cpp

@@ -122,6 +122,7 @@ void TritonCTS::runTritonCts()
   sinkBuffers_.clear();
   regTreeRootBufIndex_ = 0;
   delayBufIndex_ = 0;
+  options_->setMaxWl(0);
   options_->removeOwner();
   logger_->info(CTS, 500, "Runtime: {:.2f}s", timer.elapsed());
 }
@@ -244,7 +245,9 @@ void TritonCTS::setupCharacterization()
 
   double maxWlMicrons
       = resizer_->findMaxWireLength(/* don't issue error */ false) * 1e+6;
-  options_->setMaxWl(block_->micronsToDbu(maxWlMicrons));
+  if (maxWlMicrons > 0) {
+    options_->setMaxWl(block_->micronsToDbu(maxWlMicrons));
+  }
 
   // A new characteriztion is always created.
   techChar_ = std::make_unique<TechChar>(