set up GetTagId

compiler/mono/src/inc_dec.rs

@@ -129,6 +129,12 @@ pub fn occurring_variables_expr(expr: &Expr<'_>, result: &mut MutSet<Symbol>) {
         }
 
         EmptyArray | RuntimeErrorFunction(_) | Literal(_) => {}
+
+        GetTagId {
+            structure: symbol, ..
+        } => {
+            result.insert(*symbol);
+        }
     }
 }
 
@@ -753,6 +759,19 @@ impl<'a> Context<'a> {
                 // function pointers are persistent
                 self.arena.alloc(Stmt::Let(z, v, l, b))
             }
+
+            GetTagId { structure: x, .. } => {
+                let b = self.add_dec_if_needed(x, b, b_live_vars);
+                let info_x = self.get_var_info(x);
+                let b = if info_x.consume {
+                    self.add_inc(z, 1, b)
+                } else {
+                    b
+                };
+
+                self.arena.alloc(Stmt::Let(z, v, l, b))
+            }
+
         };
 
         (new_b, live_vars)