path enum for transparent low latch

Signed-off-by: James Cherry <cherry@parallaxsw.com>

liberty/Liberty.cc

@@ -1914,13 +1914,17 @@ LibertyCell::latchEnable(TimingArcSet *d_to_q_set,
 			 FuncExpr *&enable_func,
 			 const RiseFall *&enable_edge) const
 {
-  enable_port = nullptr;
   LatchEnable *latch_enable = latch_d_to_q_map_.findKey(d_to_q_set);
   if (latch_enable) {
     enable_port = latch_enable->enable();
     enable_func = latch_enable->enableFunc();
     enable_edge = latch_enable->enableEdge();
   }
+  else {
+    enable_port = nullptr;
+    enable_func = nullptr;
+    enable_edge = nullptr;
+  }
 }
 
 const RiseFall *

liberty/LibertyReader.cc

@@ -3927,8 +3927,8 @@ LibertyReader::endTiming(LibertyGroup *group)
 {
   if (timing_) {
     // Set scale factor type in constraint tables.
-    for (auto tr : RiseFall::range()) {
-      TableModel *model = timing_->constraint(tr);
+    for (auto rf : RiseFall::range()) {
+      TableModel *model = timing_->constraint(rf);
       if (model) {
 	ScaleFactorType type=timingTypeScaleFactorType(timing_->attrs()->timingType());
 	model->setScaleFactorType(type);

search/PathEnum.cc

@@ -399,7 +399,7 @@ PathEnumFaninVisitor::reportDiversion(TimingArc *div_arc,
     report_->reportLine("path_enum:  from %s -> %s",
                         div_prev.name(this),
                         before_div_.name(this));
-    report_->reportLine("path_enum:    to %s ->e",
+    report_->reportLine("path_enum:    to %s",
                         after_div->name(this));
   }
 }
@@ -502,9 +502,6 @@ PathEnum::makeDiversions(PathEnd *path_end,
   path.prevPath(this, prev_path, prev_arc);
   PathEnumFaninVisitor fanin_visitor(path_end, path, unique_pins_, this);
   while (prev_arc
-         // Do not enumerate beyond latch D to Q edges.
-         // This breaks latch loop paths.
-         && prev_arc->role() != TimingRole::latchDtoQ()
          // Do not enumerate paths in the clk network.
          && !path.isClock(this)) {
     // Fanin visitor does all the work.
@@ -512,6 +509,10 @@ PathEnum::makeDiversions(PathEnd *path_end,
     // previous path and arc as well as diversions.
     fanin_visitor.visitFaninPathsThru(path.vertex(this),
                                       prev_path.vertex(this), prev_arc);
+    // Do not enumerate beyond latch D to Q edges.
+    // This breaks latch loop paths.
+    if (prev_arc->role() == TimingRole::latchDtoQ())
+      break;
     path.init(prev_path);
     path.prevPath(this, prev_path, prev_arc);
   }
@@ -574,7 +575,7 @@ PathEnum::updatePathHeadDelays(PathEnumedSeq &paths,
 			       Path *after_div)
 {
   Tag *prev_tag = after_div->tag(this);
-  ClkInfo *clk_info = prev_tag->clkInfo();
+  ClkInfo *prev_clk_info = prev_tag->clkInfo();
   Arrival prev_arrival = search_->clkPathArrival(after_div);
   for (int i = paths.size() - 1; i >= 0; i--) {
     PathEnumed *path = paths[i];
@@ -585,19 +586,22 @@ PathEnum::updatePathHeadDelays(PathEnumedSeq &paths,
       ArcDelay arc_delay = search_->deratedDelay(edge->from(graph_),
                                                  arc, edge, false, path_ap);
       Arrival arrival = prev_arrival + arc_delay;
-      debugPrint(debug_, "path_enum", 3, "update arrival %s %s -> %s",
-                 path->name(this),
+      debugPrint(debug_, "path_enum", 3, "update arrival %s %s %s -> %s",
+                 path->vertex(this)->name(network_),
+                 path->tag(this)->asString(this),
                  delayAsString(path->arrival(this), this),
                  delayAsString(arrival, this));
       path->setArrival(arrival, this);
       prev_arrival = arrival;
-      if (sdc_->crprActive()) {
+      if (sdc_->crprActive()
+          // D->Q paths use the EN->Q clk info so no need to update.
+          && arc->role() != TimingRole::latchDtoQ()) {
         // When crpr is enabled the diverion may be from another crpr clk pin,
         // so update the tags to use the corresponding ClkInfo.
         Tag *tag = path->tag(this);
         Tag *updated_tag = search_->findTag(path->transition(this),
                                             path_ap,
-                                            clk_info,
+                                            prev_clk_info,
                                             tag->isClock(),
                                             tag->inputDelay(),
                                             tag->isSegmentStart(),

search/Tag.cc

@@ -97,11 +97,12 @@ Tag::asString(bool report_index,
   string result;
 
   if (report_index)
-    result += std::to_string(index_) + " ";
+    result += std::to_string(index_);
 
   if (report_rf_min_max) {
     const RiseFall *rf = transition();
     PathAnalysisPt *path_ap = corners->findPathAnalysisPt(path_ap_index_);
+    result += " ";
     result += rf->asString();
     result += " ";
     result += path_ap->pathMinMax()->asString();
@@ -109,6 +110,7 @@ Tag::asString(bool report_index,
     result += std::to_string(path_ap_index_);
   }
 
+  result += " ";
   const ClockEdge *clk_edge = clkEdge();
   if (clk_edge)
     result += clk_edge->name();

tcl/StaTcl.i

@@ -4901,9 +4901,8 @@ latch_d_to_q_en()
     FuncExpr *enable_func;
     const RiseFall *enable_rf;
     lib_cell->latchEnable(d_q_set, enable_port, enable_func, enable_rf);
-    const char *en_name = enable_port->name();
-    return stringPrintTmp("%s %s", en_name, enable_rf->asString());
-
+    if (enable_port)
+      return stringPrintTmp("%s %s", enable_port->name(), enable_rf->asString());
   }
   return "";
 }