Fork fission bufferize

• Refactor fork fission, add fork fission bufferized version.
• Add test that uses fork fission to create extra forks.

hercules_opt/src/fork_transforms.rs

@@ -322,8 +322,6 @@ pub fn fork_bufferize_fission_helper<'a, 'b>(
 where
     'a: 'b,
 {
-    // Returns the two forks that it generates.
-
     if bufferized_edges.is_empty() {
         return None;
     }
@@ -384,7 +382,6 @@ where
                 .replace_all_uses_where(old_node, map[&old_node], |node| *node == outside_user)?;
         }
 
-        let new_join = map[&join];
         let new_fork = map[&fork];
 
         // FIXME: Do this as part of copy subgraph?
@@ -422,12 +419,14 @@ where
             ));
             let empty_buffer = edit.add_zero_constant(empty_buffer);
             let empty_buffer = edit.add_node(Node::Constant { id: empty_buffer });
+            edit = edit.add_schedule(empty_buffer, Schedule::NoResetConstant)?;
             let reduce = Node::Reduce {
                 control: join,
                 init: empty_buffer,
                 reduct: write,
             };
             let reduce = edit.add_node(reduce);
+            edit = edit.add_schedule(reduce, Schedule::ParallelReduce)?;
 
             // Fix write node
             edit = edit.replace_all_uses_where(NodeID::new(0), reduce, |usee| *usee == write)?;
@@ -449,12 +448,11 @@ where
         Ok(edit)
     });
 
-    if edit_result == false {
-        todo!();
-        return None;
+    if edit_result {
+        Some((fork, new_fork_id))
+    } else {
+        None
     }
-
-    Some((fork, new_fork_id))
 }
 
 /** Split a 1D fork into a separate fork for each reduction. */