Modified dead group removal to retain references to group ports withi…

…n FSMs

calyx-ir/src/structure.rs

@@ -861,6 +861,56 @@ impl FSM {
             .expect(&msg)
             .extend(assigns);
     }
+
+    pub fn get_called_groups(&self) -> Vec<Id> {
+        // groups that are used in the transitions section of this FSM
+        let mut called_groups = self
+            .transitions
+            .iter()
+            .flat_map(|trans| match trans {
+                Transition::Unconditional(_) => vec![],
+                Transition::Conditional(conds) => {
+                    conds.iter().flat_map(|(guard, _)| {
+                        let mut group_names = vec![];
+                        guard.all_ports().iter().for_each(|port| {
+                            if let PortParent::Group(group_wref) =
+                                &port.borrow().parent
+                            {
+                                group_names
+                                    .push(group_wref.upgrade().borrow().name());
+                            }
+                        });
+                        group_names
+                    })
+                }
+                .collect(),
+            })
+            .collect_vec();
+
+        // groups that are used in the assignments section
+
+        called_groups.extend(
+            self.assignments
+                .iter()
+                .flat_map(|assigns| {
+                    let mut groups_accessed = vec![];
+                    for assign in assigns.iter() {
+                        assign.iter_ports().for_each(|port| {
+                            if let PortParent::Group(group_wref) =
+                                &port.borrow().parent
+                            {
+                                groups_accessed
+                                    .push(group_wref.upgrade().borrow().name());
+                            }
+                        });
+                    }
+                    groups_accessed
+                })
+                .collect_vec(),
+        );
+
+        called_groups
+    }
 }
 
 impl GetName for Cell {

calyx-opt/src/passes/dead_group_removal.rs

@@ -34,6 +34,18 @@ impl Visitor for DeadGroupRemoval {
         Ok(Action::Continue)
     }
 
+    fn fsm_enable(
+        &mut self,
+        s: &mut calyx_ir::FSMEnable,
+        _comp: &mut calyx_ir::Component,
+        _sigs: &LibrarySignatures,
+        _comps: &[calyx_ir::Component],
+    ) -> VisResult {
+        // add all groups that are assigned to / read from, by the parent FSM
+        self.used_groups.extend(s.fsm.borrow().get_called_groups());
+        Ok(Action::Continue)
+    }
+
     fn static_enable(
         &mut self,
         s: &mut ir::StaticEnable,
@@ -117,6 +129,11 @@ impl Visitor for DeadGroupRemoval {
             }
         }
 
+        // for now, add all groups invoked by each fsm
+        for fsm in comp.get_fsms().iter() {
+            self.used_groups.extend(fsm.borrow().get_called_groups());
+        }
+
         // Remove Groups that are not used
         comp.get_groups_mut()
             .retain(|g| self.used_groups.contains(&g.borrow().name()));