Add some logging to optimize code

src/optimize/inline_iife.rs

@@ -15,6 +15,8 @@ impl Transform for InlineIife {
             let changes = transform(nodes, id);
             cost = 1 + cost.saturating_sub(changes);
         });
+
+        log::debug!("Applied inline_iife transform. Cost: {:?}", cost);
         cost
     }
 }

src/optimize/inline_let.rs

@@ -16,6 +16,8 @@ impl Transform for InlineLet {
             let changes = transform(nodes, id);
             cost = 1 + cost.saturating_sub(changes);
         });
+
+        log::debug!("Applied inline_let transform. Cost: {:?}", cost);
         cost
     }
 }

src/optimize/mod.rs

@@ -24,6 +24,11 @@ pub fn optimize(expr: &mut ir::Expr, opts: Opts) {
     while budget != 0 {
         let cost = pass.transform(expr);
         budget = budget.saturating_sub(cost);
+        log::debug!(
+            "Applied optimisation pass. Total cost: {}. Remaining budget: {}",
+            cost,
+            budget
+        );
     }
 }