Merge pull request #327 from The-OpenROAD-Project/driver-vertex-level-cache

added driver vertex levelization

graph/Graph.i

@@ -28,6 +28,7 @@
 #include "Graph.hh"
 #include "FuncExpr.hh"
 #include "TimingRole.hh"
+#include "search/Levelize.hh"
 #include "Liberty.hh"
 #include "Network.hh"
 #include "Clock.hh"
@@ -118,6 +119,32 @@ remove_delay_slew_annotations()
   Sta::sta()->removeDelaySlewAnnotations();
 }
 
+void
+report_levelized_drvr_vertices(int max_count)
+{
+  Sta *sta = Sta::sta();
+  sta->ensureGraph();
+  const VertexSeq &drvrs = sta->levelizedDrvrVertices();
+  Report *report = sta->report();
+  const Network *network = sta->network();
+  report->report("driver vertex count {}", drvrs.size());
+  Level prev_level = -1;
+  int n = 0;
+  for (Vertex *vertex : drvrs) {
+    Level level = vertex->level();
+    if (level < prev_level)
+      report->report("level order violated {} {} < {}",
+                     network->pathName(vertex->pin()),
+                     level, prev_level);
+    if (n < max_count)
+      report->report("{} level={}",
+                     network->pathName(vertex->pin()),
+                     level);
+    prev_level = level;
+    n++;
+  }
+}
+
 %} // inline
 
 ////////////////////////////////////////////////////////////////

include/sta/Sta.hh

@@ -1325,6 +1325,7 @@ public:
   // Ensure that the timing graph has been built.
   Graph *ensureGraph();
   void ensureClkArrivals();
+  const VertexSeq& levelizedDrvrVertices();
 
   // Find all arc delays and vertex slews with delay calculator.
   virtual void findDelays();

search/Levelize.cc

@@ -53,7 +53,8 @@ Levelize::Levelize(StaState *sta) :
   level_space_(10),
   roots_(makeVertexSet(sta)),
   relevelize_from_(makeVertexSet(sta)),
-  observer_(nullptr)
+  observer_(nullptr),
+  drvr_vertices_level_valid_(false)
 {
 }
 
@@ -90,6 +91,8 @@ Levelize::clear()
   loops_.clear();
   loop_edges_.clear();
   max_level_ = 0;
+  drvr_vertices_level_valid_ = false;
+  levelized_drvr_vertices_.clear();
 }
 
 void
@@ -546,6 +549,7 @@ Levelize::setLevel(Vertex *vertex,
 void
 Levelize::invalid()
 {
+  drvr_vertices_level_valid_ = false;
   if (levelized_) {
     debugPrint(debug_, "levelize", 1, "levels invalid");
     levelized_ = false;
@@ -559,6 +563,8 @@ Levelize::deleteVertexBefore(Vertex *vertex)
   if (levelized_) {
     roots_.erase(vertex);
     relevelize_from_.erase(vertex);
+    drvr_vertices_level_valid_ = false;
+    levelized_drvr_vertices_.clear();
   }
 }
 
@@ -570,6 +576,7 @@ Levelize::relevelizeFrom(Vertex *vertex)
                vertex->to_string(this));
     relevelize_from_.insert(vertex);
     levels_valid_ = false;
+    drvr_vertices_level_valid_ = false;
   }
 }
 
@@ -584,6 +591,7 @@ Levelize::deleteEdgeBefore(Edge *edge)
     // fails because the DFS path will be missing.
     levelized_ = false;
     levels_valid_ = false;
+    drvr_vertices_level_valid_ = false;
   }
 }
 
@@ -710,6 +718,36 @@ Levelize::checkLevels()
   }
 }
 
+void
+Levelize::levelizeDrvrVertices()
+{
+  levelized_drvr_vertices_.clear();
+  // Rough estimate: ~half of vertices are drivers
+  levelized_drvr_vertices_.reserve(graph_->vertexCount() / 2);
+  VertexIterator vertex_iter(graph_);
+  while (vertex_iter.hasNext()) {
+    Vertex *vertex = vertex_iter.next();
+    if (vertex->isDriver(network_))
+      levelized_drvr_vertices_.emplace_back(vertex);
+  }
+  sort(levelized_drvr_vertices_,
+       [this](const Vertex *a, const Vertex *b) {
+         if (a->level() != b->level())
+           return a->level() < b->level();
+         return VertexNameLess(network_)(a, b);
+       });
+  drvr_vertices_level_valid_ = true;
+}
+
+const VertexSeq &
+Levelize::levelizedDrvrVertices()
+{
+  ensureLevelized();
+  if (!drvr_vertices_level_valid_)
+    levelizeDrvrVertices();
+  return levelized_drvr_vertices_;
+}
+
 ////////////////////////////////////////////////////////////////
 
 GraphLoop::GraphLoop(EdgeSeq *edges) :

search/Levelize.hh

@@ -74,7 +74,8 @@ public:
   void checkLevels();
   // Public for regression testing.
   void levelize();
-
+  const VertexSeq &levelizedDrvrVertices();
+  
 protected:
   void findRoots();
   VertexSeq sortedRootsWithFanout();
@@ -104,6 +105,7 @@ protected:
   void clearLoopEdges();
   void deleteLoops();
   void reportPath(EdgeSeq &path) const;
+  void levelizeDrvrVertices();
 
   bool levelized_;
   bool levels_valid_;
@@ -116,6 +118,8 @@ protected:
   EdgeSet disabled_loop_edges_;
   EdgeSet latch_d_to_q_edges_;
   LevelizeObserver *observer_;
+  VertexSeq levelized_drvr_vertices_;
+  bool drvr_vertices_level_valid_;
 };
 
 // Loops broken by levelization may not necessarily be combinational.

search/Sta.cc

@@ -2900,6 +2900,12 @@ Sta::ensureClkArrivals()
   search_->findClkArrivals();
 }
 
+const VertexSeq&
+Sta::levelizedDrvrVertices()
+{
+  return levelize_->levelizedDrvrVertices();
+}
+
 ////////////////////////////////////////////////////////////////
 
 VertexSet &

test/levelize_drvr_vertices1.ok

@@ -0,0 +1,127 @@
+OpenSTA 3.1.0 211aea7497 Copyright (c) 2026, Parallax Software, Inc.
+License GPLv3: GNU GPL version 3 <http://gnu.org/licenses/gpl.html>
+
+This is free software, and you are free to change and redistribute it
+under certain conditions; type `show_copying' for details. 
+This program comes with ABSOLUTELY NO WARRANTY; for details type `show_warranty'.
+Warning 198: gcd_asap7.v line 844, module FAx1_ASAP7_75t_R not found. Creating black box for _106_.
+Warning 198: gcd_asap7.v line 925, module HAxp5_ASAP7_75t_R not found. Creating black box for _115_.
+Warning 198: gcd_asap7.v line 1079, module XOR2x2_ASAP7_75t_R not found. Creating black box for _140_.
+Warning 198: gcd_asap7.v line 1159, module OR2x2_ASAP7_75t_R not found. Creating black box for _156_.
+Warning 198: gcd_asap7.v line 1164, module OA21x2_ASAP7_75t_R not found. Creating black box for _157_.
+Warning 198: gcd_asap7.v line 1170, module OAI21x1_ASAP7_75t_R not found. Creating black box for _158_.
+Warning 198: gcd_asap7.v line 1210, module NOR2x1_ASAP7_75t_R not found. Creating black box for _165_.
+Warning 198: gcd_asap7.v line 1219, module OR4x1_ASAP7_75t_R not found. Creating black box for _167_.
+Warning 198: gcd_asap7.v line 1232, module AO21x1_ASAP7_75t_R not found. Creating black box for _169_.
+Warning 198: gcd_asap7.v line 1265, module NAND2x1_ASAP7_75t_R not found. Creating black box for _175_.
+Warning 198: gcd_asap7.v line 1313, module AO221x1_ASAP7_75t_R not found. Creating black box for _184_.
+Warning 198: gcd_asap7.v line 3244, module TIEHIx1_ASAP7_75t_R not found. Creating black box for _216_.
+Warning 198: gcd_asap7.v line 3251, module AOI211x1_ASAP7_75t_R not found. Creating black box for _218_.
+Warning 198: gcd_asap7.v line 3258, module AND3x1_ASAP7_75t_R not found. Creating black box for _219_.
+Warning 198: gcd_asap7.v line 3269, module OA211x2_ASAP7_75t_R not found. Creating black box for _221_.
+Warning 198: gcd_asap7.v line 3735, module OAI22x1_ASAP7_75t_R not found. Creating black box for _305_.
+Warning 198: gcd_asap7.v line 4197, module AND4x1_ASAP7_75t_R not found. Creating black box for _386_.
+Warning 198: gcd_asap7.v line 4204, module AND5x1_ASAP7_75t_R not found. Creating black box for _387_.
+Warning 198: gcd_asap7.v line 4259, module DFFHQNx1_ASAP7_75t_R not found. Creating black box for \ctrl.state.out[0]$_DFF_P_ .
+driver vertex count 106
+clk level=0
+req_msg[0] level=0
+req_msg[10] level=0
+req_msg[11] level=0
+req_msg[12] level=0
+req_msg[13] level=0
+req_msg[14] level=0
+req_msg[15] level=0
+req_msg[16] level=0
+req_msg[17] level=0
+req_msg[18] level=0
+req_msg[19] level=0
+req_msg[1] level=0
+req_msg[20] level=0
+req_msg[21] level=0
+req_msg[22] level=0
+req_msg[23] level=0
+req_msg[24] level=0
+req_msg[25] level=0
+req_msg[26] level=0
+req_msg[27] level=0
+req_msg[28] level=0
+req_msg[29] level=0
+req_msg[2] level=0
+req_msg[30] level=0
+req_msg[31] level=0
+req_msg[3] level=0
+req_msg[4] level=0
+req_msg[5] level=0
+req_msg[6] level=0
+req_msg[7] level=0
+req_msg[8] level=0
+req_msg[9] level=0
+req_val level=0
+reset level=0
+resp_rdy level=0
+_215_/_129_/Y level=10
+_215_/_130_/Y level=10
+_215_/_131_/Y level=10
+_215_/_132_/Y level=10
+_215_/_133_/Y level=10
+_215_/_134_/Y level=10
+_215_/_135_/Y level=10
+_215_/_136_/Y level=10
+_215_/_137_/Y level=10
+_215_/_138_/Y level=10
+_215_/_139_/Y level=10
+_215_/_166_/Y level=10
+_215_/_174_/Y level=10
+_215_/_180_/Y level=10
+_215_/_182_/Y level=10
+_215_/_186_/Y level=10
+_215_/_193_/Y level=10
+_217_/Y level=10
+_222_/Y level=10
+_224_/Y level=10
+_227_/Y level=10
+_228_/Y level=10
+_229_/Y level=10
+_230_/Y level=10
+_231_/Y level=10
+_232_/Y level=10
+_233_/Y level=10
+_234_/Y level=10
+_235_/Y level=10
+_236_/Y level=10
+_237_/Y level=10
+_238_/Y level=10
+_239_/Y level=10
+_240_/Y level=10
+_241_/Y level=10
+_242_/Y level=10
+_243_/Y level=10
+_244_/Y level=10
+_245_/Y level=10
+_354_/Y level=10
+_357_/Y level=10
+_361_/Y level=10
+_365_/Y level=10
+_368_/Y level=10
+_373_/Y level=10
+_376_/Y level=10
+_380_/Y level=10
+_384_/Y level=10
+_388_/Y level=10
+_393_/Y level=10
+_395_/Y level=10
+_396_/Y level=10
+_278_/Y level=20
+_282_/Y level=20
+_286_/Y level=20
+_291_/Y level=20
+_296_/Y level=20
+_301_/Y level=20
+_304_/Y level=20
+_308_/Y level=20
+_312_/Y level=20
+_315_/Y level=20
+_320_/Y level=20
+_323_/Y level=20
+% 

test/levelize_drvr_vertices1.tcl

@@ -0,0 +1,14 @@
+# Test for Levelize::levelizedDrvrVertices() API.
+# Verifies:
+#   1. Returns driver vertices in non-decreasing level order
+#   2. All returned vertices are drivers
+source helpers.tcl
+read_liberty asap7/asap7sc7p5t_INVBUF_RVT_TT_nldm_220122.lib.gz
+read_liberty asap7/asap7sc7p5t_INVBUF_LVT_TT_nldm_220122.lib.gz
+read_liberty asap7/asap7sc7p5t_INVBUF_SLVT_TT_nldm_220122.lib.gz
+read_verilog gcd_asap7.v
+link_design gcd
+create_clock -name clk -period 500 {clk}
+
+# Report first 100 driver vertices in level order and total count
+sta::report_levelized_drvr_vertices 100

test/regression_vars.tcl

@@ -148,6 +148,7 @@ record_public_tests {
   get_lib_pins_of_objects
   get_noargs
   get_objrefs
+  levelized_drvr_vertices1  
   liberty_arcs_one2one_1
   liberty_arcs_one2one_2
   liberty_backslash_eol