diff --git a/src/opt/gvn.rs b/src/opt/gvn.rs
index 9c8b832..f7a2485 100644
--- a/src/opt/gvn.rs
+++ b/src/opt/gvn.rs
@@ -17,7 +17,6 @@ pub struct GvnInner {}
 
 impl Optimize<FunctionDefinition> for GvnInner {
     fn optimize(&mut self, code: &mut FunctionDefinition) -> bool {
-        println!("hihi2352352");
         let cfg = make_cfg(code);
         let mut reverse_cfg = reverse_cfg(&cfg);
         let domtree = Domtree::new(code.bid_init, &cfg, &reverse_cfg);
@@ -28,31 +27,21 @@ impl Optimize<FunctionDefinition> for GvnInner {
         let init_leader_table = leader_tables.entry(code.bid_init).or_default();
         let mut replaces = HashMap::new();
 
-        for (aid, _) in code.allocations.iter().enumerate() {
-            let number = get_register_number(
-                RegisterId::local(aid),
-                &mut register_table,
-                &expression_table,
-                init_leader_table,
-            );
-        }
-        println!("hihi4");
-
         for bid in domtree.rpo() {
-            traverse_rpo(
+            visit_block(
                 *bid,
                 code,
                 &mut reverse_cfg,
                 &domtree,
-                &mut register_table,
-                &mut expression_table,
-                &mut leader_tables,
+                (
+                    &mut register_table,
+                    &mut expression_table,
+                    &mut leader_tables,
+                ),
                 &mut replaces,
             );
         }
 
-        println!("replaces: {replaces:?}");
-
         let mut result = false;
 
         for (bid, block) in code.blocks.iter_mut() {
@@ -64,118 +53,105 @@ impl Optimize<FunctionDefinition> for GvnInner {
                 changed = replace_exit_operands(&mut block.exit, &replaces) || changed;
 
                 result = result || changed;
-
                 if !changed {
                     break;
                 }
             }
         }
 
-        println!("hihi2");
-
         result
     }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-enum Operand {
+enum Number {
     Number(usize),
-    IrOperand(ir::Operand),
+    Constant(Constant),
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 enum Expression {
     BinOp {
         op: ast::BinaryOperator,
-        lhs: Operand,
-        rhs: Operand,
+        lhs: Number,
+        rhs: Number,
     },
     UnaryOp {
         op: ast::UnaryOperator,
-        operand: Operand,
+        operand: Number,
     },
     TypeCast {
-        value: Operand,
+        value: Number,
         target_dtype: Dtype,
     },
     GetElementPtr {
-        ptr: Operand,
-        offset: Operand,
+        ptr: Number,
+        offset: Number,
         dtype: Dtype,
     },
 }
 
-fn get_register_number(
-    rid: RegisterId,
-    register_table: &mut HashMap<RegisterId, NumberOrConstant>,
-    expression_table: &HashMap<Expression, usize>,
-    leader_table: &mut HashMap<usize, RegisterOrConstant>,
-) -> NumberOrConstant {
-    let len = register_table.len() + expression_table.len();
-    let number = register_table
-        .entry(rid)
-        .or_insert(NumberOrConstant::Number(len))
-        .clone();
-    if let NumberOrConstant::Number(number) = number {
-        let _unused = leader_table.insert(number, RegisterOrConstant::Register(rid));
-    }
-    println!("[REG] {number:?}={rid:?}");
-    number
-}
-
-fn get_expression_number(
-    expr: Expression,
-    register_table: &HashMap<RegisterId, NumberOrConstant>,
-    expression_table: &mut HashMap<Expression, usize>,
-) -> usize {
-    let len = register_table.len() + expression_table.len();
-    let number = *expression_table.entry(expr.clone()).or_insert(len);
-    println!("[EXPR] {number}={expr:?}");
-    number
-}
-
-#[derive(Clone, Debug)]
-enum RegisterOrConstant {
+#[derive(Debug, Clone)]
+enum LeaderValue {
     Register(RegisterId),
     Constant(Constant),
 }
 
-#[derive(Clone, Debug, Hash, Eq, PartialEq)]
-enum NumberOrConstant {
-    Number(usize),
-    Constant(Constant),
+fn get_register_number(
+    rid: RegisterId,
+    register_table: &mut HashMap<RegisterId, Number>,
+    expression_table: &HashMap<Expression, usize>,
+    leader_table: &mut HashMap<usize, LeaderValue>,
+) -> Number {
+    let len = register_table.len() + expression_table.len();
+    register_table
+        .entry(rid)
+        .or_insert_with(|| {
+            let _unused = leader_table.insert(len, LeaderValue::Register(rid));
+            Number::Number(len)
+        })
+        .clone()
 }
 
-fn traverse_rpo(
+fn get_expression_number(
+    expr: Expression,
+    register_table: &HashMap<RegisterId, Number>,
+    expression_table: &mut HashMap<Expression, usize>,
+) -> usize {
+    let len = register_table.len() + expression_table.len();
+    *expression_table.entry(expr).or_insert(len)
+}
+
+type NumberingInfo<'a> = (
+    &'a mut HashMap<RegisterId, Number>,
+    &'a mut HashMap<Expression, usize>,
+    &'a mut HashMap<BlockId, HashMap<usize, LeaderValue>>,
+);
+
+fn visit_block(
     bid: BlockId,
     code: &mut FunctionDefinition,
     reverse_cfg: &mut HashMap<BlockId, Vec<(BlockId, JumpArg)>>,
     domtree: &Domtree,
-    register_table: &mut HashMap<RegisterId, NumberOrConstant>,
-    expression_table: &mut HashMap<Expression, usize>,
-    leader_tables: &mut HashMap<BlockId, HashMap<usize, RegisterOrConstant>>,
-    replaces: &mut HashMap<RegisterId, ir::Operand>,
+    (register_table, expression_table, leader_tables): NumberingInfo<'_>,
+    replaces: &mut HashMap<RegisterId, Operand>,
 ) {
-    println!("bid: {bid}");
-
     let block = code.blocks.get_mut(&bid).unwrap();
-    let idom_leader_table = domtree
+    let mut predecessors = reverse_cfg.get_mut(&bid);
+    let mut leader_table = domtree
         .idom(&bid)
         .and_then(|bid_idom| leader_tables.get(bid_idom))
         .cloned()
         .unwrap_or_default();
-    // let leader_table = leader_tables.entry(bid).or_insert(idom_leader_table);
-    let mut leader_table = idom_leader_table;
 
-    let mut predecessors = reverse_cfg.get_mut(&bid);
     if let Some(ref predecessors) = predecessors {
-        for (aid, _) in block.phinodes.iter().enumerate() {
+        for aid in 0..block.phinodes.len() {
             let rid = RegisterId::arg(bid, aid);
             let numbers = predecessors
                 .iter()
                 .map(|(_, arg)| match &arg.args[aid] {
-                    ir::Operand::Constant(constant) => NumberOrConstant::Constant(constant.clone()),
-                    ir::Operand::Register { rid, .. } => get_register_number(
+                    Operand::Constant(constant) => Number::Constant(constant.clone()),
+                    Operand::Register { rid, .. } => get_register_number(
                         *rid,
                         register_table,
                         expression_table,
@@ -184,17 +160,15 @@ fn traverse_rpo(
                 })
                 .collect::<HashSet<_>>();
             if numbers.len() == 1 {
-                let number = numbers.iter().next().unwrap().clone();
-                match number {
-                    NumberOrConstant::Number(number) => {
-                        let _unused = register_table.insert(rid, NumberOrConstant::Number(number));
-                        let _unused =
-                            leader_table.insert(number, RegisterOrConstant::Register(rid));
+                match numbers.iter().next().unwrap().clone() {
+                    Number::Number(number) => {
+                        let _unused = register_table.insert(rid, Number::Number(number));
+                        let _unused = leader_table.insert(number, LeaderValue::Register(rid));
                     }
-                    NumberOrConstant::Constant(constant) => {
+                    Number::Constant(constant) => {
                         let _unused =
-                            register_table.insert(rid, NumberOrConstant::Constant(constant.clone()));
-                        let _unused = replaces.insert(rid, ir::Operand::constant(constant.clone()));
+                            register_table.insert(rid, Number::Constant(constant.clone()));
+                        let _unused = replaces.insert(rid, Operand::constant(constant.clone()));
                     }
                 }
             } else {
@@ -207,129 +181,71 @@ fn traverse_rpo(
     let mut phinode_allocs = HashMap::new();
 
     for (i, inst) in block.instructions.iter_mut().enumerate() {
-        let expr = match inst.deref().deref() {
-            Instruction::BinOp { op, lhs, rhs, .. } => Expression::BinOp {
-                op: op.clone(),
-                lhs: ir_operand_to_gvn_operand(
-                    lhs,
-                    register_table,
-                    expression_table,
-                    &mut leader_table,
-                ),
-                rhs: ir_operand_to_gvn_operand(
-                    rhs,
-                    register_table,
-                    expression_table,
-                    &mut leader_table,
-                ),
-            },
-            Instruction::UnaryOp { op, operand, .. } => Expression::UnaryOp {
-                op: op.clone(),
-                operand: ir_operand_to_gvn_operand(
-                    operand,
-                    register_table,
-                    expression_table,
-                    &mut leader_table,
-                ),
-            },
-            Instruction::TypeCast {
-                value,
-                target_dtype,
-            } => Expression::TypeCast {
-                value: ir_operand_to_gvn_operand(
-                    value,
-                    register_table,
-                    expression_table,
-                    &mut leader_table,
-                ),
-                target_dtype: target_dtype.clone(),
-            },
-            Instruction::GetElementPtr { ptr, offset, dtype } => Expression::GetElementPtr {
-                ptr: ir_operand_to_gvn_operand(
-                    ptr,
-                    register_table,
-                    expression_table,
-                    &mut leader_table,
-                ),
-                offset: ir_operand_to_gvn_operand(
-                    offset,
-                    register_table,
-                    expression_table,
-                    &mut leader_table,
-                ),
-                dtype: dtype.clone(),
-            },
-            _ => continue,
-        };
-        let number = get_expression_number(expr, register_table, expression_table);
         let rid = RegisterId::temp(bid, i);
-
-        println!("{i} {number} {expression_table:?} {leader_table:?}");
+        let number = get_expression_number(
+            if let Some(expr) = to_expression(
+                inst.deref(),
+                register_table,
+                expression_table,
+                &mut leader_table,
+            ) {
+                expr
+            } else {
+                continue;
+            },
+            register_table,
+            expression_table,
+        );
 
         if let Some(leader_value) = leader_table.get(&number) {
             match leader_value {
-                RegisterOrConstant::Register(leader_value) => {
-                    let _unused = register_table.insert(rid, NumberOrConstant::Number(number));
+                LeaderValue::Register(rid_leader_value) => {
+                    let _unused = register_table.insert(rid, Number::Number(number));
                     let _unused =
-                        replaces.insert(rid, ir::Operand::register(*leader_value, inst.dtype()));
+                        replaces.insert(rid, Operand::register(*rid_leader_value, inst.dtype()));
                 }
-                RegisterOrConstant::Constant(constant) => {
-                    let _unused = replaces.insert(rid, ir::Operand::constant(constant.clone()));
+                LeaderValue::Constant(constant) => {
+                    let _unused = replaces.insert(rid, Operand::constant(constant.clone()));
                 }
             }
         } else {
             if let Some(ref mut predecessors) = predecessors {
-                println!("하위 {predecessors:?} {leader_tables:?}");
                 if predecessors.iter().all(|(bid_predecessor, _)| {
                     leader_tables
                         .get(bid_predecessor)
-                        .and_then(|leader_table| Some(leader_table.contains_key(&number)))
-                        .unwrap_or(false)
+                        .is_some_and(|leader_table| leader_table.contains_key(&number))
                 }) {
-                    println!("상위");
-
-                    let phinode_index = block.phinodes.len();
+                    let rid_phinode = RegisterId::arg(bid, block.phinodes.len());
                     block.phinodes.push(Named::new(None, inst.dtype()));
-                    let _unused = register_table.insert(
-                        RegisterId::arg(bid, phinode_index),
-                        NumberOrConstant::Number(number),
-                    );
-                    let _unused = leader_table.insert(
-                        number,
-                        RegisterOrConstant::Register(RegisterId::arg(bid, phinode_index)),
-                    );
-                    let _unused = replaces.insert(
-                        rid,
-                        ir::Operand::register(RegisterId::arg(bid, phinode_index), inst.dtype()),
-                    );
+
+                    let _unused = register_table.insert(rid_phinode, Number::Number(number));
+                    let _unused = leader_table.insert(number, LeaderValue::Register(rid_phinode));
+                    let _unused =
+                        replaces.insert(rid, Operand::register(rid_phinode, inst.dtype()));
 
                     for (bid_predecessor, jump_arg) in predecessors.iter_mut() {
-                        let new_arg = match &leader_tables[bid_predecessor][&number] {
-                            RegisterOrConstant::Register(rid) => {
-                                ir::Operand::register(*rid, inst.dtype())
-                            }
-                            RegisterOrConstant::Constant(constant) => {
-                                ir::Operand::constant(constant.clone())
-                            }
-                        };
-                        jump_arg.args.push(new_arg.clone());
-                        let _ = phinode_allocs
+                        phinode_allocs
                             .entry(*bid_predecessor)
                             .or_insert_with(Vec::new)
-                            .push(new_arg);
+                            .push(match &leader_tables[bid_predecessor][&number] {
+                                LeaderValue::Register(rid) => Operand::register(*rid, inst.dtype()),
+                                LeaderValue::Constant(constant) => {
+                                    Operand::constant(constant.clone())
+                                }
+                            });
                     }
 
                     continue;
                 }
             }
 
-            let _unused = leader_table.insert(number, RegisterOrConstant::Register(rid));
-            let _unused = register_table.insert(rid, NumberOrConstant::Number(number));
+            let _unused = leader_table.insert(number, LeaderValue::Register(rid));
+            let _unused = register_table.insert(rid, Number::Number(number));
         }
     }
 
-    for (p_bid, new_args) in phinode_allocs {
-        match &mut code.blocks.get_mut(&p_bid).unwrap().exit {
+    for (bid_target, new_args) in phinode_allocs {
+        match &mut code.blocks.get_mut(&bid_target).unwrap().exit {
             BlockExit::Jump { arg } => {
                 fill_jump_args(bid, arg, new_args);
             }
@@ -340,10 +256,10 @@ fn traverse_rpo(
                 fill_jump_args(bid, arg_else, new_args);
             }
             BlockExit::Switch { default, cases, .. } => {
-                fill_jump_args(bid, default, new_args.clone());
                 for (_, arg) in cases {
                     fill_jump_args(bid, arg, new_args.clone());
                 }
+                fill_jump_args(bid, default, new_args);
             }
             _ => (),
         }
@@ -352,26 +268,53 @@ fn traverse_rpo(
     let _unused = leader_tables.insert(bid, leader_table);
 }
 
-fn ir_operand_to_gvn_operand(
-    operand: &ir::Operand,
-    register_table: &mut HashMap<RegisterId, NumberOrConstant>,
+fn to_expression(
+    inst: &Instruction,
+    register_table: &mut HashMap<RegisterId, Number>,
     expression_table: &HashMap<Expression, usize>,
-    leader_table: &mut HashMap<usize, RegisterOrConstant>,
-) -> Operand {
-    match operand {
-        ir::Operand::Register { rid, .. } => {
-            match get_register_number(*rid, register_table, expression_table, leader_table) {
-                NumberOrConstant::Number(number) => Operand::Number(number),
-                NumberOrConstant::Constant(constant) => {
-                    Operand::IrOperand(ir::Operand::Constant(constant))
-                }
-            }
-        }
-        _ => Operand::IrOperand(operand.clone()),
+    leader_table: &mut HashMap<usize, LeaderValue>,
+) -> Option<Expression> {
+    match inst {
+        Instruction::BinOp { op, lhs, rhs, .. } => Some(Expression::BinOp {
+            op: op.clone(),
+            lhs: get_operand_number(lhs, register_table, expression_table, leader_table),
+            rhs: get_operand_number(rhs, register_table, expression_table, leader_table),
+        }),
+        Instruction::UnaryOp { op, operand, .. } => Some(Expression::UnaryOp {
+            op: op.clone(),
+            operand: get_operand_number(operand, register_table, expression_table, leader_table),
+        }),
+        Instruction::TypeCast {
+            value,
+            target_dtype,
+        } => Some(Expression::TypeCast {
+            value: get_operand_number(value, register_table, expression_table, leader_table),
+            target_dtype: target_dtype.clone(),
+        }),
+        Instruction::GetElementPtr { ptr, offset, dtype } => Some(Expression::GetElementPtr {
+            ptr: get_operand_number(ptr, register_table, expression_table, leader_table),
+            offset: get_operand_number(offset, register_table, expression_table, leader_table),
+            dtype: dtype.clone(),
+        }),
+        _ => None,
     }
 }
 
-fn fill_jump_args(bid: BlockId, arg: &mut JumpArg, mut new_args: Vec<ir::Operand>) {
+fn get_operand_number(
+    operand: &Operand,
+    register_table: &mut HashMap<RegisterId, Number>,
+    expression_table: &HashMap<Expression, usize>,
+    leader_table: &mut HashMap<usize, LeaderValue>,
+) -> Number {
+    match operand {
+        Operand::Constant(constant) => Number::Constant(constant.clone()),
+        Operand::Register { rid, .. } => {
+            get_register_number(*rid, register_table, expression_table, leader_table)
+        }
+    }
+}
+
+fn fill_jump_args(bid: BlockId, arg: &mut JumpArg, mut new_args: Vec<Operand>) {
     if bid == arg.bid {
         arg.args.append(&mut new_args);
     }
diff --git a/src/opt/opt_utils.rs b/src/opt/opt_utils.rs
index 80d6a7b..ff69108 100644
--- a/src/opt/opt_utils.rs
+++ b/src/opt/opt_utils.rs
@@ -52,30 +52,6 @@ pub(crate) fn reverse_cfg(
     result
 }
 
-fn traverse_rpo(bid_init: BlockId, cfg: &HashMap<BlockId, Vec<JumpArg>>) -> Vec<BlockId> {
-    fn traverse_po(
-        bid: BlockId,
-        cfg: &HashMap<BlockId, Vec<JumpArg>>,
-        visited: &mut HashSet<BlockId>,
-        post_order: &mut Vec<BlockId>,
-    ) {
-        for jump in &cfg[&bid] {
-            if visited.insert(jump.bid) {
-                traverse_po(jump.bid, cfg, visited, post_order);
-            }
-        }
-        post_order.push(bid);
-    }
-
-    let mut visited = HashSet::new();
-    let _ = visited.insert(bid_init);
-    let mut order = Vec::new();
-
-    traverse_po(bid_init, cfg, &mut visited, &mut order);
-    order.reverse();
-    order
-}
-
 pub(crate) struct Domtree {
     idoms: HashMap<BlockId, BlockId>,
     inverse_idoms: HashMap<BlockId, HashSet<BlockId>>,
@@ -191,6 +167,30 @@ impl Domtree {
     }
 }
 
+fn traverse_rpo(bid_init: BlockId, cfg: &HashMap<BlockId, Vec<JumpArg>>) -> Vec<BlockId> {
+    fn traverse_po(
+        bid: BlockId,
+        cfg: &HashMap<BlockId, Vec<JumpArg>>,
+        visited: &mut HashSet<BlockId>,
+        post_order: &mut Vec<BlockId>,
+    ) {
+        for jump in &cfg[&bid] {
+            if visited.insert(jump.bid) {
+                traverse_po(jump.bid, cfg, visited, post_order);
+            }
+        }
+        post_order.push(bid);
+    }
+
+    let mut visited = HashSet::new();
+    let _ = visited.insert(bid_init);
+    let mut order = Vec::new();
+
+    traverse_po(bid_init, cfg, &mut visited, &mut order);
+    order.reverse();
+    order
+}
+
 fn intersect_idom(
     lhs: Option<BlockId>,
     mut rhs: BlockId,
@@ -292,10 +292,7 @@ pub(crate) fn replace_exit_operands(
     }
 }
 
-pub(crate) fn replace_operand(
-    operand: &mut Operand,
-    replaces: &HashMap<RegisterId, Operand>,
-) -> bool {
+fn replace_operand(operand: &mut Operand, replaces: &HashMap<RegisterId, Operand>) -> bool {
     if let Operand::Register { rid, .. } = operand {
         if let Some(new_operand) = replaces.get(rid) {
             if (operand != new_operand) {