eval latches out of bfs

Signed-off-by: James Cherry <cherry@CerezoBook.local>

include/sta/Search.hh

@@ -75,6 +75,8 @@ using ExceptionPathSeq = std::vector<ExceptionPath*>;
 class Search : public StaState
 {
 public:
+  bool postpone_latch_outputs_{false};
+
   Search(StaState *sta);
   ~Search() override;
   void copyState(const StaState *sta) override;
@@ -530,9 +532,6 @@ protected:
                              const MinMax *min_max) const;
   void seedRequireds();
   void seedInvalidRequireds();
-  [[nodiscard]] bool havePendingLatchOutputs();
-  void clearPendingLatchOutputs();
-  void enqueuePendingLatchOutputs();
   void findFilteredArrivals(bool thru_latches);
   void findArrivalsSeed();
   void seedFilterStarts();
@@ -669,7 +668,6 @@ protected:
   std::mutex filtered_arrivals_lock_;
 
   bool found_downstream_clk_pins_{false};
-  bool postpone_latch_outputs_{false};
   std::vector<Path*> enum_paths_;
 
   VisitPathEnds *visit_path_ends_;

search/PathEnum.cc

@@ -356,7 +356,9 @@ PathEnumFaninVisitor::visitFaninPathsThru(Path *before_div,
   prev_vertex_ = prev_vertex;
   visited_fanins_.clear();
   unique_edge_divs_.clear();
+  search_->postpone_latch_outputs_ = false;
   visitFaninPaths(before_div_->vertex(this));
+  search_->postpone_latch_outputs_ = true;
 
   if (unique_edges_) {
     for (auto [vertex_edge, div] : unique_edge_divs_)
@@ -422,6 +424,14 @@ PathEnumFaninVisitor::visitFromToPath(const Pin *,
                                       Arrival & /* to_arrival */,
                                       const MinMax *)
 {
+    debugPrint(debug_, "path_enum", 3, "visit fanin {} -> {} {} {}",
+               from_path->to_string(this),
+               to_vertex->to_string(this), to_rf->shortName(),
+               delayAsString(
+                   search_->deratedDelay(
+                       from_vertex, arc, edge, false, from_path->minMax(this),
+                       from_path->dcalcAnalysisPtIndex(this), from_path->sdc(this)),
+                   this));
   // These paths fanin to before_div_ so we know to_vertex matches.
   if ((!unique_pins_ || from_vertex != prev_vertex_)
       && (!unique_edges_ || from_vertex != prev_vertex_

search/Search.cc

@@ -326,7 +326,7 @@ Search::clear()
   deletePathGroups();
   deletePaths();
   deleteTags();
-  clearPendingLatchOutputs();
+  pending_latch_outputs_.clear();
   pending_clk_endpoints_.clear();
   deleteFilter();
   found_downstream_clk_pins_ = false;
@@ -644,18 +644,26 @@ Search::findFilteredArrivals(bool thru_latches)
   // Search always_to_endpoint to search from exisiting arrivals at
   // fanin startpoints to reach -thru/-to endpoints.
   arrival_visitor_->init(true, false, eval_pred_);
-  // Iterate until data arrivals at all latches stop changing.
-  postpone_latch_outputs_ = true;
   enqueuePendingClkFanouts();
-  for (int pass = 1; pass == 1 || (thru_latches && havePendingLatchOutputs());
+  postpone_latch_outputs_ = true;
+  bool have_pending_latch_outputs = false;
+  // Iterate until data arrivals at all latches stop changing.
+  for (int pass = 1;
+       pass == 1 || (thru_latches && have_pending_latch_outputs);
        pass++) {
-    if (thru_latches)
-      enqueuePendingLatchOutputs();
     debugPrint(debug_, "search", 1, "find arrivals pass {}", pass);
+
     int arrival_count = arrival_iter_->visitParallel(max_level, arrival_visitor_);
-    deleteTagsPrev();
     debugPrint(debug_, "search", 1, "found {} arrivals", arrival_count);
+
+    have_pending_latch_outputs = !pending_latch_outputs_.empty();
     postpone_latch_outputs_ = false;
+    for (Vertex *latch_vertex : pending_latch_outputs_)
+      arrival_visitor_->visit(latch_vertex);
+    pending_latch_outputs_.clear();
+    postpone_latch_outputs_ = true;
+
+    deleteTagsPrev();
   }
   arrivals_exist_ = true;
 }
@@ -983,41 +991,23 @@ Search::findAllArrivals(bool thru_latches,
   if (!clks_only)
     enqueuePendingClkFanouts();
   arrival_visitor_->init(false, clks_only, eval_pred_);
-  // Iterate until data arrivals at all latches stop changing.
   postpone_latch_outputs_ = true;
-  for (int pass = 1; pass == 1 || (thru_latches && havePendingLatchOutputs());
+  bool have_pending_latch_outputs = false;
+  // Iterate until data arrivals at all latches stop changing.
+  for (int pass = 1; pass == 1 || (thru_latches && have_pending_latch_outputs);
        pass++) {
-    enqueuePendingLatchOutputs();
     debugPrint(debug_, "search", 1, "find arrivals pass {}", pass);
     findArrivals1(levelize_->maxLevel());
-    if (pass > 2)
-      postpone_latch_outputs_ = false;
+
+    have_pending_latch_outputs = !pending_latch_outputs_.empty();
+    postpone_latch_outputs_ = false;
+    for (Vertex *latch_vertex : pending_latch_outputs_)
+      arrival_visitor_->visit(latch_vertex);
+    pending_latch_outputs_.clear();
+    postpone_latch_outputs_ = true;
   }
 }
 
-bool
-Search::havePendingLatchOutputs()
-{
-  return !pending_latch_outputs_.empty();
-}
-
-void
-Search::clearPendingLatchOutputs()
-{
-  pending_latch_outputs_.clear();
-}
-
-void
-Search::enqueuePendingLatchOutputs()
-{
-  for (Vertex *latch_vertex : pending_latch_outputs_) {
-    debugPrint(debug_, "search", 2, "enqueue latch output {}",
-               latch_vertex->to_string(this));
-    arrival_iter_->enqueue(latch_vertex);
-  }
-  clearPendingLatchOutputs();
-}
-
 void
 Search::enqueuePendingClkFanouts()
 {
@@ -1148,6 +1138,17 @@ ArrivalVisitor::visit(Vertex *vertex)
 {
   debugPrint(debug_, "search", 2, "find arrivals {}",
              vertex->to_string(this));
+
+  if (search_->postponeLatchOutputs()) {
+    VertexInEdgeIterator edge_iter(vertex, graph_);
+    while (edge_iter.hasNext()) {
+      Edge *edge = edge_iter.next();
+      if (edge->role()->isLatchDtoQ()) {
+        search_->enqueueLatchOutput(edge->to(graph_));
+        return;
+      }
+    }
+  }
   Pin *pin = vertex->pin();
   tag_bldr_->init(vertex);
   has_fanin_one_ = graph_->hasFaninOne(vertex);
@@ -2139,26 +2140,7 @@ PathVisitor::visitFromPath(const Pin *from_pin,
   }
   else if (edge->role() == TimingRole::latchDtoQ()) {
     if (min_max == MinMax::max() && clk) {
-      bool postponed = false;
-      if (search_->postponeLatchOutputs()) {
-        const Path *from_clk_path = from_clk_info->crprClkPath(this);
-        if (from_clk_path) {
-          Vertex *d_clk_vertex = from_clk_path->vertex(this);
-          Level d_clk_level = d_clk_vertex->level();
-          Level q_level = to_vertex->level();
-          if (d_clk_level >= q_level) {
-            // Crpr clk path on latch data input is required to find Q
-            // arrival. If the data clk path level is >= Q level the
-            // crpr clk path prev_path pointers are not complete.
-            debugPrint(debug_, "search", 3, "postponed latch eval {} {} -> {} {}",
-                       d_clk_level, d_clk_vertex->to_string(this),
-                       edge->to_string(this), q_level);
-            postponed = true;
-            search_->enqueueLatchOutput(to_vertex);
-          }
-        }
-      }
-      if (!postponed) {
+      if (!search_->postponeLatchOutputs()) {
         arc_delay = search_->deratedDelay(from_vertex, arc, edge, false, min_max,
                                           dcalc_ap, sdc);
         latches_->latchOutArrival(from_path, arc, edge, to_tag, arc_delay,