Using a larger branch complexity than default for LVS full test's netlist compare

In addition: typo fixed, added doc for complexity configuration
parameters.

src/db/db/dbNetlistCompare.cc

@@ -786,7 +786,7 @@ private:
    *  @brief Compares edges as "less"
    *  Edge comparison is based on the pins attached (name of the first pin).
    */
-  static bool edge_less (const db::Net *a, const db::Net *b);
+  static bool net_less (const db::Net *a, const db::Net *b);
 
   /**
    *  @brief Compares edges as "equal"
@@ -1260,8 +1260,8 @@ NetGraphNode::operator< (const NetGraphNode &node) const
     }
   }
   if (m_edges.empty ()) {
-    //  do a more detailed analysis on the edges
-    return edge_less (net (), node.net ());
+    //  do a more detailed analysis on the nets involved
+    return net_less (net (), node.net ());
   }
   return false;
 }
@@ -1285,7 +1285,7 @@ NetGraphNode::operator== (const NetGraphNode &node) const
 }
 
 bool
-NetGraphNode::edge_less (const db::Net *a, const db::Net *b)
+NetGraphNode::net_less (const db::Net *a, const db::Net *b)
 {
   if ((a != 0) != (b != 0)) {
     return (a != 0) < (b != 0);

src/lvs/lvs/built-in-macros/_lvs_engine.rb

@@ -131,6 +131,18 @@ module LVS
     # @synopsis max_res(threshold)
     # See \Netter#max_res for a description of that function.
 
+    # %LVS%
+    # @name max_branch_complexity
+    # @brief Configures the maximum branch complexity for ambiguous net matching
+    # @synopsis max_branch_complexity(n)
+    # See \Netter#max_branch_complexity for a description of that function.
+
+    # %LVS%
+    # @name max_depth
+    # @brief Configures the maximum search depth for net match deduction
+    # @synopsis max_depth(n)
+    # See \Netter#max_depth for a description of that function.
+
     %w(schematic compare same_nets same_circuits same_device_classes equivalent_pins min_caps max_res max_depth max_branch_complexity).each do |f|
       eval <<"CODE"
         def #{f}(*args)

src/lvs/lvs/built-in-macros/_lvs_netter.rb

@@ -371,11 +371,41 @@ module LVS
       @comparer.max_resistance = value.to_f
     end
 
+    # %LVS%
+    # @name max_depth
+    # @brief Configures the maximum search depth for net match deduction
+    # @synopsis max_depth(n)
+    # The netlist compare algorithm works recursively: once a net
+    # equivalence is established, additional matches are derived from
+    # this equivalence. Such equivalences in turn are used to derive
+    # new equivalences and so on. The maximum depth parameter configures
+    # the number of recursions the algorithm performs before picking
+    # the next net. With higher values for the depth, the algorithm
+    # pursues this "deduction path" in greater depth while with 
+    # smaller values, the algorithm prefers picking nets in a random fashion
+    # as the seeds for this deduction path. The default value is 8. 
+
     def max_depth(value)
       lvs_data
       @comparer.max_depth = value.to_i
     end
 
+    # @name max_branch_complexity
+    # @brief Configures the maximum branch complexity for ambiguous net matching
+    # @synopsis max_branch_complexity(n)
+    # The netlist compare algorithm is basically a backtracing algorithm.
+    # With ambiguous nets, the algorithm picks possible net pairs and
+    # tries whether they will make a good match. Following the deduction
+    # path for this nets may lead to further branches if more ambiguous
+    # nets are encountered. To avoid combinational explosion, the maximum
+    # branch complexity is limited to the value configured with this 
+    # function. The default value is 100 which means not more than
+    # 100 combinations are tried for a single seed pair. For networks
+    # with inherent ambiguity such as decoders, the complexity
+    # can be increased at the expense of potentially larger runtimes.
+    # The runtime penality is roughly proportional to the branch
+    # complexity.
+ 
     def max_branch_complexity(value)
       lvs_data
       @comparer.max_branch_complexity = value.to_i

src/lvs/unit_tests/lvsTests.cc

@@ -87,6 +87,8 @@ void run_test (tl::TestBase *_this, const std::string &suffix, const std::string
   //  output, but this will essentially verify the output netlist's consistency.
   db::NetlistCrossReference xref;
   db::NetlistComparer comparer (&xref);
+  comparer.set_max_branch_complexity (500);
+  comparer.set_max_depth (20);
   bool res = comparer.compare (&nl1, &nl2);
   if (! res) {
     tl::info << "Netlist mismatch:";