fix least_common_ancestor

hercules_ir/src/dom.rs

@@ -82,10 +82,10 @@ impl DomTree {
      * ancestor of the two nodes that is as far down the tree as possible.
      */
     pub fn least_common_ancestor(&self, mut a: NodeID, mut b: NodeID) -> NodeID {
-        while self.idom[&a].0 < self.idom[&b].0 {
+        while self.idom[&a].0 > self.idom[&b].0 {
             a = self.idom[&a].1;
         }
-        while self.idom[&a].0 > self.idom[&b].0 {
+        while self.idom[&a].0 < self.idom[&b].0 {
             b = self.idom[&b].1;
         }
         while a != b {