2.0.11

CMakeLists.txt

@@ -16,7 +16,7 @@
 
 cmake_minimum_required (VERSION 3.9)
 
-project(STA VERSION 2.0.10)
+project(STA VERSION 2.0.11)
 
 set(CMAKE_VERBOSE_MAKEFILE ON)
 set(CMAKE_CXX_STANDARD 11)

search/Search.cc

@@ -227,8 +227,8 @@ Search::Search(StaState *sta) :
 void
 Search::init(StaState *sta)
 {
-  crpr_path_pruning_enabled_ = true;
-  unconstrained_paths_ = false;
+  initVars();
+
   search_adj_ = new SearchThru(nullptr, sta);
   eval_pred_ = new EvalPred(sta);
   check_crpr_ = new CheckCrpr(sta);
@@ -264,6 +264,15 @@ Search::init(StaState *sta)
   found_downstream_clk_pins_ = false;
 }
 
+// Init "options".
+void
+Search::initVars()
+{
+  unconstrained_paths_ = false;
+  crpr_path_pruning_enabled_ = true;
+  crpr_approx_missing_requireds_ = true;
+}
+
 Search::~Search()
 {
   deletePaths();
@@ -292,8 +301,8 @@ Search::~Search()
 void
 Search::clear()
 {
-  crpr_path_pruning_enabled_ = true;
-  unconstrained_paths_ = false;
+  initVars();
+
   clk_arrivals_valid_ = false;
   arrivals_at_endpoints_exist_ = false;
   arrivals_seeded_ = false;
@@ -328,6 +337,18 @@ Search::setCrprpathPruningEnabled(bool enabled)
   crpr_path_pruning_enabled_ = enabled;
 }
 
+bool
+Search::crprApproxMissingRequireds() const
+{
+  return crpr_approx_missing_requireds_;
+}
+
+void
+Search::setCrprApproxMissingRequireds(bool enabled)
+{
+  crpr_approx_missing_requireds_ = enabled;
+}
+
 void
 Search::deleteTags()
 {
@@ -3436,7 +3457,7 @@ RequiredVisitor::visitFromToPath(const Pin *,
 				 Tag *to_tag,
 				 Arrival &,
 				 const MinMax *min_max,
-				 const PathAnalysisPt *)
+				 const PathAnalysisPt *path_ap)
 {
   // Don't propagate required times through latch D->Q edges.
   if (edge->role() != TimingRole::latchDtoQ()) {
@@ -3469,8 +3490,35 @@ RequiredVisitor::visitFromToPath(const Pin *,
 		  delayAsString(required_cmp_->required(arrival_index), sta_));
       required_cmp_->requiredSet(arrival_index, from_required, req_min);
     }
-    else
+    else {
+      if (sta_->search()->crprApproxMissingRequireds()) {
+	// Arrival on to_vertex that differs by crpr_pin was pruned.
+	// Find an arrival that matches everything but the crpr_pin
+	// as an appromate required.
+	VertexPathIterator to_iter(to_vertex, to_tr, path_ap, sta_);
+	while (to_iter.hasNext()) {
+	  PathVertex *to_path = to_iter.next();
+	  Tag *to_path_tag = to_path->tag(sta_);
+	  if (tagMatchNoCrpr(to_path_tag, to_tag)) {
+	    Required to_required = to_path->required(sta_);
+	    Required from_required = to_required - arc_delay;
+	    debugPrint2(debug, "search", 3, "  to tag   %2u: %s\n",
+			to_path_tag->index(),
+			to_path_tag->asString(sta_));
+	    debugPrint5(debug, "search", 3, "  %s - %s = %s %s %s\n",
+			delayAsString(to_required, sta_),
+			delayAsString(arc_delay, sta_),
+			delayAsString(from_required, sta_),
+			min_max == MinMax::max() ? "<" : ">",
+			delayAsString(required_cmp_->required(arrival_index),
+				      sta_));
+	    required_cmp_->requiredSet(arrival_index, from_required, req_min);
+	    break;
+	  }
+	}
+      }
       from_vertex->setRequiredsPruned(true);
+    }
     // Propagate requireds pruned flag backwards.
     if (to_vertex->requiredsPruned())
       from_vertex->setRequiredsPruned(true);

search/Search.hh

@@ -70,10 +70,15 @@ public:
   // Reset to virgin state.
   void clear();
   // When enabled, non-critical path arrivals are pruned to improve
-  // run time and reduce memory. The side-effect is that slacks for
-  // non-critical paths on intermediate pins may be incorrect.
+  // run time and reduce memory.
   bool crprPathPruningEnabled() const;
   void setCrprpathPruningEnabled(bool enabled);
+  // When path pruning is enabled required times for non-critical paths
+  // that have been pruned require additional search. This option
+  // disables additional search to returns approximate required times.
+  bool crprApproxMissingRequireds() const;
+  void setCrprApproxMissingRequireds(bool enabled);
+
   bool unconstrainedPaths() const { return unconstrained_paths_; }
   // from/thrus/to are owned and deleted by Search.
   // Use corner nullptr to report timing for all corners.
@@ -344,6 +349,7 @@ public:
 
 protected:
   void init(StaState *sta);
+  void initVars();
   void makeAnalysisPts(AnalysisType analysis_type);
   void makeAnalysisPts(bool swap_clk_min_max,
 		       bool report_min,
@@ -524,6 +530,8 @@ protected:
 
   // findPathEnds arg.
   bool unconstrained_paths_;
+  bool crpr_path_pruning_enabled_;
+  bool crpr_approx_missing_requireds_;
   // Search predicates.
   SearchPred *search_adj_;
   SearchPred *search_clk_;
@@ -591,7 +599,6 @@ protected:
   VisitPathEnds *visit_path_ends_;
   GatedClk *gated_clk_;
   CheckCrpr *check_crpr_;
-  bool crpr_path_pruning_enabled_;
   Genclks *genclks_;
 };
 

search/Sta.cc

@@ -2880,13 +2880,14 @@ Sta::findRequired(Vertex *vertex)
   search_->findRequireds(vertex->level());
   if (sdc_->crprEnabled()
       && search_->crprPathPruningEnabled()
+      && !search_->crprApproxMissingRequireds()
       // Clocks invariably have requireds that are pruned but isn't
       // worth finding arrivals and requireds all over again for
       // the entire fanout of the clock.
       && !search_->isClock(vertex)
       && vertex->requiredsPruned()) {
     // Invalidate arrivals and requireds and disable
-    // path pruning on fanout vertices.
+    // path pruning on fanout vertices with DFS.
     int fanout = 0;
     disableFanoutCrprPruning(vertex, fanout);
     debugPrint2(debug_, "search", 1, "resurrect pruned required %s fanout %d\n",
@@ -2898,8 +2899,6 @@ Sta::findRequired(Vertex *vertex)
   }
 }
 
-// DFS to invalidate fanout arrivals and requireds to
-// find arrivals with pruning disabled.
 void
 Sta::disableFanoutCrprPruning(Vertex *vertex,
 			      int &fanout)