rename_execute_retire: don't include completed instructions in space used by a unit

crates/cpu/src/rename_execute_retire.rs

@@ -581,6 +581,15 @@ impl MOpInUnitState {
             Self::FinishedAndOrCausedCancel => None,
         }
     }
+    fn is_completed(self) -> bool {
+        match self {
+            Self::NotYetEnqueued => false,
+            Self::InputsNotReadySpeculative { .. } => false,
+            Self::InputsReady { .. } => false,
+            Self::OutputReady { .. } => false,
+            Self::FinishedAndOrCausedCancel => true,
+        }
+    }
 }
 
 impl fmt::Debug for MOpInUnitState {
@@ -1213,7 +1222,7 @@ impl<C: PhantomConstCpuConfig> RenameExecuteRetireState<C> {
     fn space_available_for_unit(&self, unit_index: usize) -> usize {
         let mut retval = self.config.get().unit_max_in_flight(unit_index);
         for renamed in self.rob.renamed() {
-            if renamed.unit_index == unit_index {
+            if renamed.unit_index == unit_index && !renamed.mop_in_unit_state.is_completed() {
                 let Some(v) = NonZero::new(retval.get() - 1) else {
                     return 0;
                 };