diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/Prog.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/Prog.java
index db430dd..963b9a1 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/Prog.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/Prog.java
@@ -2,6 +2,7 @@
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.NotNull;
 import org.teachfx.antlr4.ep20.ir.stmt.CJMP;
 import org.teachfx.antlr4.ep20.ir.stmt.FuncEntryLabel;
 import org.teachfx.antlr4.ep20.ir.stmt.JMP;
@@ -33,17 +34,19 @@ public void addBlock(LinearIRBlock linearIRBlock) {
         blockList.add(linearIRBlock);
     }
 
-    private void linearInstrsImpl(LinearIRBlock linearIRBlock) {
+    private void linearInstrsImpl(@NotNull LinearIRBlock linearIRBlock) {
+        // Add all instr from non-empty block
         if (!linearIRBlock.getStmts().isEmpty()) {
             if (!linearIRBlock.getJmpRefMap().isEmpty()){
-                instrs.add(new Label(linearIRBlock.toString(),null));
+                instrs.add(linearIRBlock.getLabel());
             }
             instrs.addAll(linearIRBlock.getStmts());
         } else {
+            // Drop empty block
             if (linearIRBlock.getSuccessors().isEmpty()) {
                 return;
             }
-
+            // Auto-fill next block for jmp/cjmp
             var nextBlock = linearIRBlock.getSuccessors().get(0);
             for (var ref : linearIRBlock.getJmpRefMap()){
                 if (ref instanceof JMP jmp) {
@@ -55,6 +58,7 @@ private void linearInstrsImpl(LinearIRBlock linearIRBlock) {
 
         }
 
+        // recursive call
         for(var successor : linearIRBlock.getSuccessors()){
             linearInstrsImpl(successor);
         }
diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java
index f3ae75f..85fe7ed 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/CJMP.java
@@ -6,7 +6,6 @@
 
 public class CJMP extends Stmt {
     public VarSlot cond;
-
     private LinearIRBlock thenBlock;
     private LinearIRBlock elseBlock;
 
diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/Label.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/Label.java
index af50856..07dd151 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/Label.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/ir/stmt/Label.java
@@ -1,6 +1,5 @@
 package org.teachfx.antlr4.ep20.ir.stmt;
 
-import lombok.Getter;
 import org.teachfx.antlr4.ep20.ir.IRVisitor;
 import org.teachfx.antlr4.ep20.symtab.scope.Scope;
 
@@ -10,7 +9,6 @@ public class Label extends Stmt {
 
     private Stmt nextEntry = null;
 
-
     private String rawLabel;
 
 
@@ -25,6 +23,12 @@ public Label(String rawLabel, Scope scope) {
         }
     }
 
+    public Label(Scope scope) {
+        this.scope = scope;
+        this.seq = scope.getLabelSeq();
+        this.rawLabel = null;
+    }
+
     public void setRawLabel(String rawLabel) {
         this.rawLabel = rawLabel;
     }
diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/BasicBlock.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/BasicBlock.java
index 84de4a6..0e7cc5f 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/BasicBlock.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/BasicBlock.java
@@ -1,5 +1,6 @@
 package org.teachfx.antlr4.ep20.pass.cfg;
 
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 
 import org.teachfx.antlr4.ep20.ir.IRNode;
@@ -17,7 +18,7 @@ public class BasicBlock<I extends IRNode> implements Iterable<Loc<I>> {
     // Generate codes
     public List<Loc<I>> codes;
 
-    public int id;
+    public final int id;
 
     protected Optional<Label> label;
 
@@ -45,6 +46,12 @@ public Loc<I> next() {
         };
     }
 
+    @NotNull
+    @Contract("_ -> new")
+    public static BasicBlock<IRNode> buildFromLinearBlock(@NotNull LinearIRBlock block) {
+        return new BasicBlock<IRNode>(block.getKind(), block.getOrd(), block.getStmts().stream().map(Loc::new).toList(), Optional.of(block.getLabel()));
+    }
+
     public BasicBlock(Kind kind, int id, List<Loc<I>> codes, Optional<Label> label) {
         this.codes = codes;
         this.label = label;
@@ -56,6 +63,10 @@ public int getId() {
         return id;
     }
 
+    public Optional<Label> getLabel() {
+        return label;
+    }
+
     // Generate isEmpty
     public boolean isEmpty() {
         return codes.isEmpty();
diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/CFGBuilder.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/CFGBuilder.java
index 8082445..7b32f00 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/CFGBuilder.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/CFGBuilder.java
@@ -5,7 +5,7 @@
 import java.util.List;
 
 public class CFGBuilder<I extends IRNode> {
-    public CFGBuilder(List<I> instrs){
+    public CFGBuilder(BasicBlock<IRNode> startNode){
 
     }
 }
diff --git a/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/LinearIRBlock.java b/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/LinearIRBlock.java
index f07d74b..3320a31 100644
--- a/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/LinearIRBlock.java
+++ b/ep20/src/main/java/org/teachfx/antlr4/ep20/pass/cfg/LinearIRBlock.java
@@ -10,20 +10,17 @@
 
 public class LinearIRBlock {
 
-    public Kind kind = Kind.CONTINUOUS;
+    // Fields
     private static int LABEL_SEQ = 1;
+    private Kind kind = Kind.CONTINUOUS;
+    private int ord = 1;
     private ArrayList<IRNode> stmts;
-
     private List<LinearIRBlock> successors;
-
     private List<LinearIRBlock> predecessors;
-
-    protected Scope scope = null;
-
+    private Scope scope = null;
     private List<IRNode> jmpRefMap = new ArrayList<>();
 
-    private int ord = 0;
-
+    // Constructor
     public LinearIRBlock() {
         stmts = new ArrayList<>();
         successors = new ArrayList<>();
@@ -31,6 +28,8 @@ public LinearIRBlock() {
         ord = LABEL_SEQ++;
     }
 
+    // Methods
+    // Statement Operations
     public void addStmt(IRNode stmt) {
         stmts.add(stmt);
         updateKindByLastInstr(stmt);
@@ -47,10 +46,12 @@ private void updateKindByLastInstr(IRNode stmt) {
             kind = Kind.CONTINUOUS;
         }
     }
+
     public static boolean isBasicBlock(Stmt stmt) {
         return !(stmt instanceof CJMP) && !(stmt instanceof JMP);
     }
 
+    // Getters and Setters
     public List<IRNode> getStmts() {
         return stmts;
     }
@@ -77,15 +78,6 @@ public void setPredecessors(List<LinearIRBlock> predecessors) {
         this.predecessors = predecessors;
     }
 
-    public static void setLink(LinearIRBlock current, LinearIRBlock next) {
-        current.successors.add(next);
-        next.predecessors.add(current);
-    }
-
-    public void setLink(LinearIRBlock next) {
-        LinearIRBlock.setLink(this,next);
-    }
-
     public Scope getScope() {
         return scope;
     }
@@ -94,17 +86,6 @@ public void setScope(Scope scope) {
         this.scope = scope;
     }
 
-    @Override
-    public String toString() {
-        var firstInstr = stmts.get(0);
-
-        if (firstInstr instanceof Label){
-            return firstInstr.toString();
-        }
-
-        return "L"+ord;
-    }
-
     public List<IRNode> getJmpRefMap() {
         return jmpRefMap;
     }
@@ -117,17 +98,53 @@ public int getOrd() {
         return ord;
     }
 
+    // Link Operations
+    public static void setLink(LinearIRBlock current, LinearIRBlock next) {
+        current.successors.add(next);
+        next.predecessors.add(current);
+    }
+
+    public void setLink(LinearIRBlock next) {
+        LinearIRBlock.setLink(this, next);
+    }
 
+    public Kind getKind() {
+        return kind;
+    }
+
+    // Jump Operations
     public void refJMP(IRNode node) {
         jmpRefMap.add(node);
     }
 
+    // Utility Methods
     @Override
-    public boolean equals(Object obj) {
-        return toString().equalsIgnoreCase(obj.toString());
+    public String toString() {
+        var firstInstr = stmts.get(0);
+
+        if (firstInstr instanceof FuncEntryLabel) {
+            return firstInstr.toString();
+        }
+        return "L" + ord;
     }
 
-    public IRNode getLastInstr() {
-        return stmts.get(stmts.size() - 1);
+    public String toSource(){
+        var firstInstr = stmts.get(0);
+
+        if (firstInstr instanceof FuncEntryLabel) {
+            return ((FuncEntryLabel) firstInstr).toSource();
+        }
+
+        return "L" + ord;
+    }
+
+    public Label getLabel() {
+        var firstInstr = stmts.get(0);
+
+        if (firstInstr instanceof FuncEntryLabel funcEntryLabel) {
+            return funcEntryLabel;
+        }
+
+        return new Label(toString(),scope);
     }
-}
+}
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index 3e87f4d..ce15daa 100644
--- a/pom.xml
+++ b/pom.xml
@@ -60,11 +60,6 @@
             <version>${JUnit.version}</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.projectlombok</groupId>
-            <artifactId>lombok</artifactId>
-            <version>1.18.30</version>
-        </dependency>
         <!-- JUnit Jupiter Engine for running tests -->
         <dependency>
             <groupId>org.junit.jupiter</groupId>