Remove incoming edge count optimization

Author: Hendrik van Antwerpen

stack-graphs/src/cycles.rs

@@ -116,7 +116,7 @@ where
     /// Otherwise, we return true.
     pub fn has_similar_path<Eq>(
         &mut self,
-        graph: &StackGraph,
+        _graph: &StackGraph,
         arena: &mut P::Arena,
         path: &P,
         eq: Eq,
@@ -126,10 +126,6 @@ where
     {
         let key = path.key();
 
-        if graph.incoming_edge_count(key.end_node) <= 1 {
-            // return false;
-        }
-
         let possibly_similar_paths = self.paths.entry(key).or_default();
         for other_path in possibly_similar_paths.iter() {
             if eq(arena, path, other_path) {

stack-graphs/src/graph.rs

@@ -1301,7 +1301,6 @@ impl StackGraph {
         let edges = &mut self.outgoing_edges[source];
         if let Err(index) = edges.binary_search_by_key(&sink, |o| o.sink) {
             edges.insert(index, OutgoingEdge { sink, precedence });
-            self.incoming_edges[sink] += 1;
         }
     }
 
@@ -1324,14 +1323,6 @@ impl StackGraph {
             None => Either::Left(std::iter::empty()),
         }
     }
-
-    /// Returns an iterator of all of the edges that begin at a particular source node.
-    pub fn incoming_edge_count(&self, sink: Handle<Node>) -> usize {
-        match self.incoming_edges.get(sink) {
-            Some(count) => *count,
-            None => 0,
-        }
-    }
 }
 
 //-------------------------------------------------------------------------------------------------
@@ -1419,7 +1410,6 @@ pub struct StackGraph {
     pub(crate) nodes: Arena<Node>,
     pub(crate) source_info: SupplementalArena<Node, SourceInfo>,
     node_id_handles: NodeIDHandles,
-    incoming_edges: SupplementalArena<Node, usize>,
     outgoing_edges: SupplementalArena<Node, SmallVec<[OutgoingEdge; 8]>>,
     pub(crate) debug_info: SupplementalArena<Node, DebugInfo>,
 }
@@ -1598,7 +1588,6 @@ impl Default for StackGraph {
             nodes,
             source_info: SupplementalArena::new(),
             node_id_handles: NodeIDHandles::new(),
-            incoming_edges: SupplementalArena::new(),
             outgoing_edges: SupplementalArena::new(),
             debug_info: SupplementalArena::new(),
         }