diff --git a/Reports/4.2-gvn/report.md b/Reports/4.2-gvn/report.md
index d290e359f9533ec66fe37e41d1cefaed08ed8b1a..971bfa99ad283da14a91d2dd0bda12bff45ec727 100644
--- a/Reports/4.2-gvn/report.md
+++ b/Reports/4.2-gvn/report.md
@@ -8,12 +8,265 @@
 
 ## 实验难点
 
-实验中遇到哪些挑战
+### 对于函数`detectEquivalences(G)`
+
+```cpp
+detectEquivalences(G)
+    PIN1 = {} // “1” is the first statement in the program
+    POUT1 = transferFunction(PIN1)
+    for each statement s other than the first statement in the program
+        POUTs = Top
+    while changes to any POUT occur // i.e. changes in equivalences
+        for each statement s other than the first statement in the program
+            if s appears in block b that has two predecessors
+            then
+                PINs = Join(POUTs1, POUTs2) // s1 and s2 are last statements in respective predecessors
+            else
+                PINs = POUTs3    // s3 the statement just before s
+            POUTs = transferFunction(PINs) // apply transferFunction on each statement in the block
+```
+
+- POUT、PIN是对于语句的的map，但是实现中是对于基本块的map，怎么处理区别？
+  
+  注意到基本块的pin、pout对应着首条语句的pin和末尾语句的pout，所以没有本质上的不同，主要是怎么补全中间语句的pin、pout。
+  
+  中间语句的pin、pout应该不会被显式保存，只在对基本块执行转移函数时，逐条计算。所以应该没啥问题。
+
+- 怎么设计top？
+  
+  尽管算法伪代码中，top是对每一条语句的赋值的，但是任意一条语句的都有所属基本块，只要对基本块的pout标注top、就能保证基本块的pin合乎逻辑，逐条执行转移函数后，每条语句的pin都合法。``
+
+- `while changes to any POUT occur`
+  
+  这句话如此轻松，但是在实现中出现了问题：这涉及到怎么判断分区相等，做不好会出现死循环。
+  
+  如果单纯比较index恐怕不行：因为我目前的`transferFunction`会生成一个新的等价类，赋予一个新的编号。
+  
+  所以我使用对等价类中的`members`做相等的判断，如果两个分区中的等价类都能找到相等的，那么就判断分区相等。
+  
+  > 但是这样依赖于set的排序，
+  > 
+  > - 对于分区，这个排序依赖于等价类中index的值，侥幸来说每条指令按顺序执行，即使index不一致(每次转移函数分配最新的index)，大小顺序也是一致的？
+  > 
+  > - 对于等价类，里边是`Value*`指针，这个指针的等价就是语义上的等价，没问题。
+  
+  改过来后发现还是死循环，DEBUG很久意识到我的分区相等写的有问题：`return members_ == other.members_`，这样会挨个儿比较`members_`指针的值，而不是我预想的比较指针指向的等价类。所以要手动遍历一下。
+  
+  这个遍历也不是很直观的，因为要做两层解引用：
+  
+  ```cpp
+      for (; it1 != p1.end(); ++it1, ++it2)
+          if (not(**it1 == **it2))
+              return false;
+  ```
+  
+  `*it`是等价类的指针，`**it`才是等价类。
+  
+  除此之外，我还忘了`++it2`，淦。
+  
+  改完这些，终于能跑通第一版本了……
+
+### 等价类设计
+
+> ```cpp
+> shared_ptr<Expression>
+> GVN::valueExpr(Instruction *instr);
+> ```
+
+等价类涉及到针对指令设计、常量折叠、递归计算等，很复杂，需要拎出来单独讨论。
+
+首先注意到传给传进去的参数是指令类型(指针)。需要`transferFunction`处理的指令，一次赋值的右式自然可以由指令类型得到，所以没有毛病。
+
+指令有多种类型，也即lightIR中有多种赋值方式，而非单纯的伪代码中的二元运算。但是即使是已经在算法中讨论过的二元运算，写起来也不容易。
+
+#### 生成等价类的逻辑
+
+首先讨论生成等价类的逻辑：
+
+- 二元运算`y op z`
+  
+  如果y、z都是常量，那么可以进行常量折叠，得到**一个**`ConstantExpression`类型。
+  
+  否则返回的是一个`BinaryExpression`类型，这个类型需要左右操作数，都是`Expression`类型，如果操作数是常量，使用`ConstantExpression`创建新的值表达式，否则递归调用`valueExpr`。
+  
+  > 这里为什么递归调用不会走到未定义？
+
+- phi函数
+  
+  我们逻辑上把其改变成了copy，`transferFunction`应该维护这一点，所以认为没有phi函数传入。
+  
+  具体是`transferFunction`函数中的这几句话：
+  
+  ```cpp
+  GVN::partitions
+  GVN::transferFunction(Instruction *x, Value *e, partitions pin)
+  {
+      auto e_instr = dynamic_cast<Instruction *>(e);
+      auto e_const = dynamic_cast<Constant *>(e);
+      assert((not e or e_instr or e_const) &&
+             "A value must be from an instruction or constant");
+      // ……
+      if (e) {
+          if (e_const)
+              ve = ConstantExpression::create(e_const);
+          else
+              ve = valueExpr(e_instr, &pin);
+      } else
+          ve = valueExpr(x, &pin);
+  }
+  ```
+
+- 比较函数：和二元运算一致。
+
+- 类型转换：添加新的表达式类型`CastExpression`，处理和二元操作类似。
+
+- 其他产生赋值的指令，也会由`transferFunction`传递给`ValueExpr`，这些指令是：`load`、`alloca`和返回值非空的`call`。
+  
+  这里设计一种值表达式类型：`UniqueExpression`，这个表达式和任何其他都不等价，表现为`equiv`直接返回false。
+
+#### 若干需要梳理的问题
+
+除此之外，关于等价类有几个命题一定要说明，这些是理解GVN的关键。
+
+- 等价类中的ve一定存在吗？
+  
+  根据等价类的设计，ve一定是存在的，且等价类中`members_`中一定存在元素。
+
+- ve一定唯一吗？
+  
+  从逻辑上，等价类集合中的元素享有共同的ve产生的结果，ve是唯一的
+  
+  从实现上，添加
+
+- ve或者vpf能够作为代表吗？
+  
+  这个问题源于`transferFunction`的一句话：
+  
+  > if ve or vpf is in a class Ci in POUTs
+
+- 代表元如何选取？什么时候选取？
+
+- 怎么判断等价类相等
+  
+  根据论坛上这个[例子](http://cscourse.ustc.edu.cn/forum/thread.jsp?forum=91&thread=68)，我发现值编号会有非必要的增长，即最终收敛时用到的编号是1、5、6，其中2、3、4都是迭代中用到的但是最后都没有体现。
+  
+  从这个例子中可以发现，迭代收敛时，是pout中对应分区的`members_`不变，值编号还是会变化的，所以判断等价类相等，应该比较`members_`集合。
+
+- 什么时候给新的值编号？
+  
+    1. 执行转移函数发现没有可以归属的等价类时
+  
+    2. 求交巴拉巴拉还没搞清楚那里
+
+- 等价类为空的判定，可以用`members_`做判断吗？
+  
+  我认为是可以的，存在情况：两个基本块汇合时，交出一个集合，它的members为空，但是ve不空：
+  
+  ```
+  BB0: y =
+       z =
+  ; pout: [{v1,y}, {v2,z}]
+  
+  BB1: x1 = y + z ; preds = BB0
+  ; pout: [{v1,y}, {v2,z}, {v3, x1, v1+v2}]
+  
+  BB2: x2 = y + z ; preds = BB0
+  ; pout: [{v1,y}, {v2,z}, {v4, x2, v1+v2}]
+  
+  BB3: ... ; preds = BB1, BB2
+  ```
+  
+  进入BB3时，对BB1和BB2的pout中等价类分别取交，执行`Intersect(Ci={v3, x1, v1+v2}, Cj={v4, x2, v1+v2}`，得到的是`{v1+v2}`，`members_`中没有成员，但是ve存在，我认为这种情况也应该判定结果为空集。
+  
+  因为最终反映到IR上，我们直接关心的都是`members_`中的成员，所以用`members_`的空代表等价类的空我觉得是合适的。
+
+| 类型               | 处理                        |
+| ---------------- | ------------------------- |
+| 二元运算             | 依伪代码                      |
+| 没有返回值的           | 不处理                       |
+| phi函数            | 本块中的不管，后继块的做考虑            |
+| 函数调用             | 有返回值的考虑等价类，**注意后边纯函数的处理** |
+| 产生指针(GEP、alloca) | 先为返回值单独新建等价类              |
+| 类型转换及0扩展         | 单独新建等价类                   |
+| 比较               | 根据op和操作数递归判断，应该和二元运算类似    |
+| load             | 单独新建等价类                   |
+
+### 对于函数`Intersect(Ci, Cj )`
+
+伪代码中，一个等价类是一个集合，求交后，v~k~是自然而然的在或不在新集合中，但是实现中并不这么简单，如何对这样的两个结构体进行逻辑上的取交：
+
+```cpp
+struct CongruenceClass {
+    size_t index_;
+    Value *leader_;
+    std::shared_ptr<GVNExpression::Expression> value_expr_;
+    std::shared_ptr<GVNExpression::PhiExpression> value_phi_;
+    std::set<Value *> members_;
+}
+```
+
+- 首先是Intersect的伪代码描述中，下边这句怎么在实现中体现？
+  
+  > C~k~ does not have value number
+  
+  解决：index不同的自然就交不出v~i~，相同的时候才有v~i~即value number.
+  
+  隐患：transferFunction要对v~i~有继承性，即不能每次涉及一个等价类都新开一个value number
+
+- 根据上一条讨论，得出一个观点：在伪代码中，一个等价类集合会出现的内容，在实现中的对应如下：
+  
+    - 普通变量：`members_`
+  
+    - 值表达式：`value_expr_`
+  
+    - phi函数：`value_phi_`
+  
+    - 值编号v~i~：`index`
+  
+  因此，伪代码中对集合的求交，对应到实现上，就是对以上四个域求交。
+
+### 对于函数`valuePhiFunc(ve, P)`
+
+- 输入就一个分区，实际上要用到两个前驱的分区，怎么处理？
+  
+  传入基本块做参数。
+
+- 二元运算的顺序颠倒怎么办?
+  
+  > 如phi(x1,y1)+phi(x2,y2)和phi(x1,y1)+phi(y2,x2)
+  > 
+  > 对于第二种，单纯寻找x1+y2和y1+x2肯定不合逻辑
+  
+  应该不会有这种情况：phi表达式，追根溯源是在join时产生的：
+  
+  ```cpp
+  GVN::join(const partitions &P1, const partitions &P2);
+  ```
+  
+  这里的分区是严格按照`Basicblock`的方法`get_pre_basic_blocks()`的返回顺序传入的，所以不会有担心的情况发生。
+
+### 所见非所得
+
+两方面：
+
+- 论文中伪代码对于基本块的关注不是很多，但是我们的实现一定要围绕基本块进行，这个的解决对策说到了，其实和单条语句没有本质差异。
+
+- 我们针对lightir优化，经常深入API中陷入到实现细节，还容易被C++的语言特性绊住，但是应该尝试从直观上理解：我们究竟要实现什么样的效果。这个就得去看ll文件找灵感。然后这还不够，回过头来看代码又呆住了，因为ll语句和那些类型对应不上，这个就是容易忽视的一点：看lightir类型的print函数，这个能帮我们直观地串联起实现细节和表象的ll文件。
 
 ## 实验设计
+
+### join_helper
+
+### _TOP
+
+### transferFunction(Basicblock)
+
+### 
+
 实现思路，相应代码，优化前后的IR对比（举一个例子）并辅以简单说明
 
 ### 思考题
+
 1. 请简要分析你的算法复杂度
 2. `std::shared_ptr`如果存在环形引用，则无法正确释放内存，你的 Expression 类是否存在 circular reference?
 3. 尽管本次实验已经写了很多代码，但是在算法上和工程上仍然可以对 GVN 进行改进，请简述你的 GVN 实现可以改进的地方
@@ -25,4 +278,3 @@
 ## 实验反馈（可选 不会评分）
 
 对本次实验的建议
-
diff --git a/include/lightir/Instruction.h b/include/lightir/Instruction.h
index b8571e1548142f82b7423c88dfbcfa79b7665e1b..b63c880651282f26a1f3729486c736208198c9dc 100644
--- a/include/lightir/Instruction.h
+++ b/include/lightir/Instruction.h
@@ -9,8 +9,7 @@
 class BasicBlock;
 class Function;
 
-class Instruction : public User, public llvm::ilist_node<Instruction>
-{
+class Instruction : public User, public llvm::ilist_node<Instruction> {
   public:
     enum OpID {
         // Terminator Instructions
@@ -49,11 +48,11 @@ class Instruction : public User, public llvm::ilist_node<Instruction>
     Instruction(const Instruction &) = delete;
     virtual ~Instruction() = default;
     inline const BasicBlock *get_parent() const { return parent_; }
-    inline BasicBlock       *get_parent() { return parent_; }
+    inline BasicBlock *get_parent() { return parent_; }
     void set_parent(BasicBlock *parent) { this->parent_ = parent; }
     // Return the function this instruction belongs to.
     Function *get_function();
-    Module   *get_module();
+    Module *get_module();
 
     OpID get_instr_type() const { return op_id_; }
     // clang-format off
@@ -86,8 +85,7 @@ class Instruction : public User, public llvm::ilist_node<Instruction>
     // clang-format on
     std::string get_instr_op_name() { return get_instr_op_name(op_id_); }
 
-    bool is_void()
-    {
+    bool is_void() {
         return ((op_id_ == ret) || (op_id_ == br) || (op_id_ == store) ||
                 (op_id_ == call && this->get_type()->is_void_type()));
     }
@@ -108,6 +106,7 @@ class Instruction : public User, public llvm::ilist_node<Instruction>
     bool is_fsub() { return op_id_ == fsub; }
     bool is_fmul() { return op_id_ == fmul; }
     bool is_fdiv() { return op_id_ == fdiv; }
+
     bool is_fp2si() { return op_id_ == fptosi; }
     bool is_si2fp() { return op_id_ == sitofp; }
 
@@ -118,8 +117,7 @@ class Instruction : public User, public llvm::ilist_node<Instruction>
     bool is_gep() { return op_id_ == getelementptr; }
     bool is_zext() { return op_id_ == zext; }
 
-    bool isBinary()
-    {
+    bool isBinary() {
         return (is_add() || is_sub() || is_mul() || is_div() || is_fadd() ||
                 is_fsub() || is_fmul() || is_fdiv()) &&
                (get_num_operand() == 2);
@@ -128,39 +126,34 @@ class Instruction : public User, public llvm::ilist_node<Instruction>
     bool isTerminator() { return is_br() || is_ret(); }
 
   private:
-    OpID        op_id_;
-    unsigned    num_ops_;
+    OpID op_id_;
+    unsigned num_ops_;
     BasicBlock *parent_;
 };
 
-namespace detail
-{
-    template <typename T>
-    struct tag
-    {
-        using type = T;
-    };
-    template <typename... Ts>
-    struct select_last
-    {
-        // Use a fold-expression to fold the comma operator over the parameter
-        // pack.
-        using type = typename decltype((tag<Ts>{}, ...))::type;
-    };
-    template <typename... Ts>
-    using select_last_t = typename select_last<Ts...>::type;
+namespace detail {
+template <typename T>
+struct tag {
+    using type = T;
+};
+template <typename... Ts>
+struct select_last {
+    // Use a fold-expression to fold the comma operator over the parameter
+    // pack.
+    using type = typename decltype((tag<Ts>{}, ...))::type;
+};
+template <typename... Ts>
+using select_last_t = typename select_last<Ts...>::type;
 }; // namespace detail
 
 template <class>
 inline constexpr bool always_false_v = false;
 
 template <typename Inst>
-class BaseInst : public Instruction
-{
+class BaseInst : public Instruction {
   protected:
     template <typename... Args>
-    static Inst *create(Args &&...args)
-    {
+    static Inst *create(Args &&...args) {
         if constexpr (std::is_same_v<
                           std::decay_t<detail::select_last_t<Args...>>,
                           BasicBlock *>) {
@@ -171,13 +164,10 @@ class BaseInst : public Instruction
     }
 
     template <typename... Args>
-    BaseInst(Args &&...args) : Instruction(std::forward<Args>(args)...)
-    {
-    }
+    BaseInst(Args &&...args) : Instruction(std::forward<Args>(args)...) {}
 };
 
-class BinaryInst : public BaseInst<BinaryInst>
-{
+class BinaryInst : public BaseInst<BinaryInst> {
     friend BaseInst<BinaryInst>;
 
   private:
@@ -185,35 +175,51 @@ class BinaryInst : public BaseInst<BinaryInst>
 
   public:
     // create add instruction, auto insert to bb
-    static BinaryInst *create_add(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_add(Value *v1,
+                                  Value *v2,
+                                  BasicBlock *bb,
                                   Module *m);
 
     // create sub instruction, auto insert to bb
-    static BinaryInst *create_sub(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_sub(Value *v1,
+                                  Value *v2,
+                                  BasicBlock *bb,
                                   Module *m);
 
     // create mul instruction, auto insert to bb
-    static BinaryInst *create_mul(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_mul(Value *v1,
+                                  Value *v2,
+                                  BasicBlock *bb,
                                   Module *m);
 
     // create Div instruction, auto insert to bb
-    static BinaryInst *create_sdiv(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_sdiv(Value *v1,
+                                   Value *v2,
+                                   BasicBlock *bb,
                                    Module *m);
 
     // create fadd instruction, auto insert to bb
-    static BinaryInst *create_fadd(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_fadd(Value *v1,
+                                   Value *v2,
+                                   BasicBlock *bb,
                                    Module *m);
 
     // create fsub instruction, auto insert to bb
-    static BinaryInst *create_fsub(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_fsub(Value *v1,
+                                   Value *v2,
+                                   BasicBlock *bb,
                                    Module *m);
 
     // create fmul instruction, auto insert to bb
-    static BinaryInst *create_fmul(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_fmul(Value *v1,
+                                   Value *v2,
+                                   BasicBlock *bb,
                                    Module *m);
 
     // create fDiv instruction, auto insert to bb
-    static BinaryInst *create_fdiv(Value *v1, Value *v2, BasicBlock *bb,
+    static BinaryInst *create_fdiv(Value *v1,
+                                   Value *v2,
+                                   BasicBlock *bb,
                                    Module *m);
 
     virtual std::string print() override;
@@ -222,8 +228,7 @@ class BinaryInst : public BaseInst<BinaryInst>
     void assertValid();
 };
 
-class CmpInst : public BaseInst<CmpInst>
-{
+class CmpInst : public BaseInst<CmpInst> {
     friend BaseInst<CmpInst>;
 
   public:
@@ -240,7 +245,10 @@ class CmpInst : public BaseInst<CmpInst>
     CmpInst(Type *ty, CmpOp op, Value *lhs, Value *rhs, BasicBlock *bb);
 
   public:
-    static CmpInst *create_cmp(CmpOp op, Value *lhs, Value *rhs, BasicBlock *bb,
+    static CmpInst *create_cmp(CmpOp op,
+                               Value *lhs,
+                               Value *rhs,
+                               BasicBlock *bb,
                                Module *m);
 
     CmpOp get_cmp_op() { return cmp_op_; }
@@ -253,8 +261,7 @@ class CmpInst : public BaseInst<CmpInst>
     void assertValid();
 };
 
-class FCmpInst : public BaseInst<FCmpInst>
-{
+class FCmpInst : public BaseInst<FCmpInst> {
     friend BaseInst<FCmpInst>;
 
   public:
@@ -271,8 +278,11 @@ class FCmpInst : public BaseInst<FCmpInst>
     FCmpInst(Type *ty, CmpOp op, Value *lhs, Value *rhs, BasicBlock *bb);
 
   public:
-    static FCmpInst *create_fcmp(CmpOp op, Value *lhs, Value *rhs,
-                                 BasicBlock *bb, Module *m);
+    static FCmpInst *create_fcmp(CmpOp op,
+                                 Value *lhs,
+                                 Value *rhs,
+                                 BasicBlock *bb,
+                                 Module *m);
 
     CmpOp get_cmp_op() { return cmp_op_; }
 
@@ -284,33 +294,36 @@ class FCmpInst : public BaseInst<FCmpInst>
     void assert_valid();
 };
 
-class CallInst : public BaseInst<CallInst>
-{
+class CallInst : public BaseInst<CallInst> {
     friend BaseInst<CallInst>;
 
   protected:
     CallInst(Function *func, std::vector<Value *> args, BasicBlock *bb);
 
   public:
-    static CallInst *create(Function *func, std::vector<Value *> args,
+    static CallInst *create(Function *func,
+                            std::vector<Value *> args,
                             BasicBlock *bb);
-    FunctionType    *get_function_type() const;
+    FunctionType *get_function_type() const;
 
     virtual std::string print() override;
 };
 
-class BranchInst : public BaseInst<BranchInst>
-{
+class BranchInst : public BaseInst<BranchInst> {
     friend BaseInst<BranchInst>;
 
   private:
-    BranchInst(Value *cond, BasicBlock *if_true, BasicBlock *if_false,
+    BranchInst(Value *cond,
+               BasicBlock *if_true,
+               BasicBlock *if_false,
                BasicBlock *bb);
     BranchInst(BasicBlock *if_true, BasicBlock *bb);
 
   public:
-    static BranchInst *create_cond_br(Value *cond, BasicBlock *if_true,
-                                      BasicBlock *if_false, BasicBlock *bb);
+    static BranchInst *create_cond_br(Value *cond,
+                                      BasicBlock *if_true,
+                                      BasicBlock *if_false,
+                                      BasicBlock *bb);
     static BranchInst *create_br(BasicBlock *if_true, BasicBlock *bb);
 
     bool is_cond_br() const;
@@ -318,8 +331,7 @@ class BranchInst : public BaseInst<BranchInst>
     virtual std::string print() override;
 };
 
-class ReturnInst : public BaseInst<ReturnInst>
-{
+class ReturnInst : public BaseInst<ReturnInst> {
     friend BaseInst<ReturnInst>;
 
   private:
@@ -329,13 +341,12 @@ class ReturnInst : public BaseInst<ReturnInst>
   public:
     static ReturnInst *create_ret(Value *val, BasicBlock *bb);
     static ReturnInst *create_void_ret(BasicBlock *bb);
-    bool               is_void_ret() const;
+    bool is_void_ret() const;
 
     virtual std::string print() override;
 };
 
-class GetElementPtrInst : public BaseInst<GetElementPtrInst>
-{
+class GetElementPtrInst : public BaseInst<GetElementPtrInst> {
     friend BaseInst<GetElementPtrInst>;
 
   private:
@@ -343,9 +354,10 @@ class GetElementPtrInst : public BaseInst<GetElementPtrInst>
 
   public:
     static Type *get_element_type(Value *ptr, std::vector<Value *> idxs);
-    static GetElementPtrInst *create_gep(Value *ptr, std::vector<Value *> idxs,
+    static GetElementPtrInst *create_gep(Value *ptr,
+                                         std::vector<Value *> idxs,
                                          BasicBlock *bb);
-    Type                     *get_element_type() const;
+    Type *get_element_type() const;
 
     virtual std::string print() override;
 
@@ -353,8 +365,7 @@ class GetElementPtrInst : public BaseInst<GetElementPtrInst>
     Type *element_ty_;
 };
 
-class StoreInst : public BaseInst<StoreInst>
-{
+class StoreInst : public BaseInst<StoreInst> {
     friend BaseInst<StoreInst>;
 
   private:
@@ -369,8 +380,7 @@ class StoreInst : public BaseInst<StoreInst>
     virtual std::string print() override;
 };
 
-class LoadInst : public BaseInst<LoadInst>
-{
+class LoadInst : public BaseInst<LoadInst> {
     friend BaseInst<LoadInst>;
 
   private:
@@ -378,15 +388,14 @@ class LoadInst : public BaseInst<LoadInst>
 
   public:
     static LoadInst *create_load(Type *ty, Value *ptr, BasicBlock *bb);
-    Value           *get_lval() { return this->get_operand(0); }
+    Value *get_lval() { return this->get_operand(0); }
 
     Type *get_load_type() const;
 
     virtual std::string print() override;
 };
 
-class AllocaInst : public BaseInst<AllocaInst>
-{
+class AllocaInst : public BaseInst<AllocaInst> {
     friend BaseInst<AllocaInst>;
 
   private:
@@ -403,8 +412,7 @@ class AllocaInst : public BaseInst<AllocaInst>
     Type *alloca_ty_;
 };
 
-class ZextInst : public BaseInst<ZextInst>
-{
+class ZextInst : public BaseInst<ZextInst> {
     friend BaseInst<ZextInst>;
 
   private:
@@ -421,8 +429,7 @@ class ZextInst : public BaseInst<ZextInst>
     Type *dest_ty_;
 };
 
-class FpToSiInst : public BaseInst<FpToSiInst>
-{
+class FpToSiInst : public BaseInst<FpToSiInst> {
     friend BaseInst<FpToSiInst>;
 
   private:
@@ -439,8 +446,7 @@ class FpToSiInst : public BaseInst<FpToSiInst>
     Type *dest_ty_;
 };
 
-class SiToFpInst : public BaseInst<SiToFpInst>
-{
+class SiToFpInst : public BaseInst<SiToFpInst> {
     friend BaseInst<SiToFpInst>;
 
   private:
@@ -457,25 +463,24 @@ class SiToFpInst : public BaseInst<SiToFpInst>
     Type *dest_ty_;
 };
 
-class PhiInst : public BaseInst<PhiInst>
-{
+class PhiInst : public BaseInst<PhiInst> {
     friend BaseInst<PhiInst>;
 
   private:
-    PhiInst(OpID op, std::vector<Value *> vals,
-            std::vector<BasicBlock *> val_bbs, Type *ty, BasicBlock *bb);
+    PhiInst(OpID op,
+            std::vector<Value *> vals,
+            std::vector<BasicBlock *> val_bbs,
+            Type *ty,
+            BasicBlock *bb);
     PhiInst(Type *ty, OpID op, unsigned num_ops, BasicBlock *bb)
-        : BaseInst<PhiInst>(ty, op, num_ops, bb)
-    {
-    }
+        : BaseInst<PhiInst>(ty, op, num_ops, bb) {}
     Value *l_val_;
 
   public:
     static PhiInst *create_phi(Type *ty, BasicBlock *bb);
-    Value          *get_lval() { return l_val_; }
-    void            set_lval(Value *l_val) { l_val_ = l_val; }
-    void            add_phi_pair_operand(Value *val, Value *pre_bb)
-    {
+    Value *get_lval() { return l_val_; }
+    void set_lval(Value *l_val) { l_val_ = l_val; }
+    void add_phi_pair_operand(Value *val, Value *pre_bb) {
         this->add_operand(val);
         this->add_operand(pre_bb);
     }
diff --git a/include/optimization/GVN.h b/include/optimization/GVN.h
index df408a550fe636e595c9b195aad4f3756426fd1b..144ddfce0fe1a7f7466721d33eef0b7630ba6d84 100644
--- a/include/optimization/GVN.h
+++ b/include/optimization/GVN.h
@@ -19,6 +19,7 @@
 #include <utility>
 #include <vector>
 
+class GVN;
 namespace GVNExpression {
 
 // fold the constant value
@@ -35,12 +36,13 @@ class ConstFolder {
 /**
  * for constructor of class derived from `Expression`, we make it public
  * because `std::make_shared` needs the constructor to be publicly available,
- * but you should call the static factory method `create` instead the constructor itself to get the desired data
+ * but you should call the static factory method `create` instead the
+ * constructor itself to get the desired data
  */
 class Expression {
   public:
     // TODO: you need to extend expression types according to testcases
-    enum gvn_expr_t { e_constant, e_bin, e_phi };
+    enum gvn_expr_t { e_constant, e_bin, e_phi, e_cast, e_gep, e_unique };
     Expression(gvn_expr_t t) : expr_type(t) {}
     virtual ~Expression() = default;
     virtual std::string print() = 0;
@@ -50,15 +52,21 @@ class Expression {
     gvn_expr_t expr_type;
 };
 
-bool operator==(const std::shared_ptr<Expression> &lhs, const std::shared_ptr<Expression> &rhs);
-bool operator==(const GVNExpression::Expression &lhs, const GVNExpression::Expression &rhs);
+bool operator==(const std::shared_ptr<Expression> &lhs,
+                const std::shared_ptr<Expression> &rhs);
+bool operator==(const GVNExpression::Expression &lhs,
+                const GVNExpression::Expression &rhs);
 
 class ConstantExpression : public Expression {
   public:
-    static std::shared_ptr<ConstantExpression> create(Constant *c) { return std::make_shared<ConstantExpression>(c); }
+    static std::shared_ptr<ConstantExpression> create(Constant *c) {
+        return std::make_shared<ConstantExpression>(c);
+    }
     virtual std::string print() { return c_->print(); }
     // we leverage the fact that constants in lightIR have unique addresses
-    bool equiv(const ConstantExpression *other) const { return c_ == other->c_; }
+    bool equiv(const ConstantExpression *other) const {
+        return c_ == other->c_;
+    }
     ConstantExpression(Constant *c) : Expression(e_constant), c_(c) {}
 
   private:
@@ -67,24 +75,31 @@ class ConstantExpression : public Expression {
 
 // arithmetic expression
 class BinaryExpression : public Expression {
+    friend class ::GVN;
+
   public:
-    static std::shared_ptr<BinaryExpression> create(Instruction::OpID op,
-                                                    std::shared_ptr<Expression> lhs,
-                                                    std::shared_ptr<Expression> rhs) {
+    static std::shared_ptr<BinaryExpression> create(
+        Instruction::OpID op,
+        std::shared_ptr<Expression> lhs,
+        std::shared_ptr<Expression> rhs) {
         return std::make_shared<BinaryExpression>(op, lhs, rhs);
     }
     virtual std::string print() {
-        return "(" + Instruction::get_instr_op_name(op_) + " " + lhs_->print() + " " + rhs_->print() + ")";
+        return "(" + Instruction::get_instr_op_name(op_) + " " + lhs_->print() +
+               " " + rhs_->print() + ")";
     }
 
     bool equiv(const BinaryExpression *other) const {
-        if (op_ == other->op_ and *lhs_ == *other->lhs_ and *rhs_ == *other->rhs_)
+        if (op_ == other->op_ and *lhs_ == *other->lhs_ and
+            *rhs_ == *other->rhs_)
             return true;
         else
             return false;
     }
 
-    BinaryExpression(Instruction::OpID op, std::shared_ptr<Expression> lhs, std::shared_ptr<Expression> rhs)
+    BinaryExpression(Instruction::OpID op,
+                     std::shared_ptr<Expression> lhs,
+                     std::shared_ptr<Expression> rhs)
         : Expression(e_bin), op_(op), lhs_(lhs), rhs_(rhs) {}
 
   private:
@@ -93,33 +108,122 @@ class BinaryExpression : public Expression {
 };
 
 class PhiExpression : public Expression {
+    friend class ::GVN;
+
   public:
-    static std::shared_ptr<PhiExpression> create(std::shared_ptr<Expression> lhs, std::shared_ptr<Expression> rhs) {
+    static std::shared_ptr<PhiExpression> create(
+        std::shared_ptr<Expression> lhs,
+        std::shared_ptr<Expression> rhs) {
         return std::make_shared<PhiExpression>(lhs, rhs);
     }
-    virtual std::string print() { return "(phi " + lhs_->print() + " " + rhs_->print() + ")"; }
+    virtual std::string print() {
+        return "(phi " + lhs_->print() + " " + rhs_->print() + ")";
+    }
     bool equiv(const PhiExpression *other) const {
         if (*lhs_ == *other->lhs_ and *rhs_ == *other->rhs_)
             return true;
         else
             return false;
     }
-    PhiExpression(std::shared_ptr<Expression> lhs, std::shared_ptr<Expression> rhs)
+    PhiExpression(std::shared_ptr<Expression> lhs,
+                  std::shared_ptr<Expression> rhs)
         : Expression(e_phi), lhs_(lhs), rhs_(rhs) {}
 
   private:
     std::shared_ptr<Expression> lhs_, rhs_;
 };
+
+// type cast expression
+class CastExpression : public Expression {
+  public:
+    static std::shared_ptr<CastExpression> create(
+        Instruction::OpID op,
+        std::shared_ptr<Expression> src,
+        Type *dest_type) {
+        return std::make_shared<CastExpression>(op, src, dest_type);
+    }
+    virtual std::string print() {
+        return "(" + dest_ty_->print() + " " +
+               Instruction::get_instr_op_name(op_) + " " + src_->print() + ")";
+    }
+
+    bool equiv(const CastExpression *other) const {
+        return op_ == other->op_ and src_ == other->src_ and
+               dest_ty_ == other->dest_ty_;
+    }
+
+    CastExpression(Instruction::OpID op,
+                   std::shared_ptr<Expression> src,
+                   Type *dest_type)
+        : Expression(e_cast), op_(op), src_(src), dest_ty_(dest_type) {}
+
+  private:
+    Instruction::OpID op_;
+    std::shared_ptr<Expression> src_;
+    Type *dest_ty_;
+};
+
+// type cast expression
+class GEPExpression : public Expression {
+  public:
+    static std::shared_ptr<GEPExpression> create(
+        std::shared_ptr<Expression> ptr,
+        std::vector<std::shared_ptr<Expression>> &idxs) {
+        return std::make_shared<GEPExpression>(ptr, idxs);
+    }
+    virtual std::string print() {
+        std::string ret = "(GEP " + ptr_->print();
+        for (auto idx : idxs_)
+            ret += " " + idx->print();
+        return ret + ")";
+    }
+
+    bool equiv(const GEPExpression *other) const {
+        if (idxs_.size() != other->idxs_.size())
+            return false;
+        for (int i = 0; i != idxs_.size(); ++i)
+            if (not(idxs_[i] == other->idxs_[i]))
+                return false;
+        return ptr_ == other->ptr_;
+    }
+
+    GEPExpression(std::shared_ptr<Expression> ptr,
+                  std::vector<std::shared_ptr<Expression>> &idxs)
+        : Expression(e_gep), ptr_(ptr), idxs_(idxs) {}
+
+  private:
+    std::shared_ptr<Expression> ptr_;
+    std::vector<std::shared_ptr<Expression>> idxs_;
+};
+
+// unique expression: not equal to any one else
+class UniqueExpression : public Expression {
+  public:
+    static std::shared_ptr<UniqueExpression> create(Instruction *instr) {
+        return std::make_shared<UniqueExpression>(instr);
+    }
+    virtual std::string print() { return "(UNIQUE " + instr_->print() + ")"; }
+
+    bool equiv(const UniqueExpression *other) const { return false; }
+
+    UniqueExpression(Instruction *instr)
+        : Expression(e_unique), instr_(instr) {}
+
+  private:
+    std::shared_ptr<Instruction> instr_;
+};
 } // namespace GVNExpression
 
 /**
  * Congruence class in each partitions
  * note: for constant propagation, you might need to add other fields
- * and for load/store redundancy detection, you most certainly need to modify the class
+ * and for load/store redundancy detection, you most certainly need to modify
+ * the class
  */
 struct CongruenceClass {
     size_t index_;
-    // representative of the congruence class, used to replace all the members (except itself) when analysis is done
+    // representative of the congruence class, used to replace all the members
+    // (except itself) when analysis is done
     Value *leader_;
     // value expression in congruence class
     std::shared_ptr<GVNExpression::Expression> value_expr_;
@@ -128,17 +232,22 @@ struct CongruenceClass {
     // equivalent variables in one congruence class
     std::set<Value *> members_;
 
-    CongruenceClass(size_t index) : index_(index), leader_{}, value_expr_{}, value_phi_{}, members_{} {}
+    CongruenceClass(size_t index)
+        : index_(index), leader_{}, value_expr_{}, value_phi_{}, members_{} {}
 
-    bool operator<(const CongruenceClass &other) const { return this->index_ < other.index_; }
+    bool operator<(const CongruenceClass &other) const {
+        return this->index_ < other.index_;
+    }
     bool operator==(const CongruenceClass &other) const;
 };
 
 namespace std {
 template <>
-// overload std::less for std::shared_ptr<CongruenceClass>, i.e. how to sort the congruence classes
+// overload std::less for std::shared_ptr<CongruenceClass>, i.e. how to sort the
+// congruence classes
 struct less<std::shared_ptr<CongruenceClass>> {
-    bool operator()(const std::shared_ptr<CongruenceClass> &a, const std::shared_ptr<CongruenceClass> &b) const {
+    bool operator()(const std::shared_ptr<CongruenceClass> &a,
+                    const std::shared_ptr<CongruenceClass> &b) const {
         // nullptrs should never appear in partitions, so we just dereference it
         return *a < *b;
     }
@@ -154,17 +263,24 @@ class GVN : public Pass {
     // init for pass metadata;
     void initPerFunction();
 
-    // fill the following functions according to Pseudocode, **you might need to add more arguments**
+    // fill the following functions according to Pseudocode, **you might need to
+    // add more arguments**
     void detectEquivalences();
     partitions join(const partitions &P1, const partitions &P2);
-    std::shared_ptr<CongruenceClass> intersect(std::shared_ptr<CongruenceClass>, std::shared_ptr<CongruenceClass>);
+    std::shared_ptr<CongruenceClass> intersect(
+        std::shared_ptr<CongruenceClass>,
+        std::shared_ptr<CongruenceClass>);
     partitions transferFunction(Instruction *x, Value *e, partitions pin);
     partitions transferFunction(BasicBlock *bb);
-    std::shared_ptr<GVNExpression::PhiExpression> valuePhiFunc(std::shared_ptr<GVNExpression::Expression>,
-                                                               const partitions &);
-    std::shared_ptr<GVNExpression::Expression> valueExpr(Instruction *instr);
-    std::shared_ptr<GVNExpression::Expression> getVN(const partitions &pout,
-                                                     std::shared_ptr<GVNExpression::Expression> ve);
+    std::shared_ptr<GVNExpression::PhiExpression> valuePhiFunc(
+        std::shared_ptr<GVNExpression::Expression>,
+        BasicBlock *bb);
+    std::shared_ptr<GVNExpression::Expression> valueExpr(
+        Instruction *instr,
+        partitions *part = nullptr);
+    std::shared_ptr<GVNExpression::Expression> getVN(
+        const partitions &pout,
+        std::shared_ptr<GVNExpression::Expression> ve);
 
     // replace cc members with leader
     void replace_cc_members();
@@ -180,6 +296,7 @@ class GVN : public Pass {
     // self add
     //
     std::uint64_t new_number() { return next_value_number_++; }
+    static int pretend_copy_stmt(Instruction *inst, BasicBlock *bb);
 
   private:
     bool dump_json_;
@@ -191,7 +308,9 @@ class GVN : public Pass {
     std::unique_ptr<DeadCode> dce_;
 
     // self add
-    std::map<Instruction*, bool> _TOP;
+    std::map<BasicBlock *, bool> _TOP;
+    partitions join_helper(BasicBlock *pre1, BasicBlock *pre2);
+    BasicBlock* curr_bb;
 };
 
 bool operator==(const GVN::partitions &p1, const GVN::partitions &p2);
diff --git a/src/cminusfc/.gitignore b/src/cminusfc/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..80d0420b11d310cde3d4c75755db4fc8c0190bc0
--- /dev/null
+++ b/src/cminusfc/.gitignore
@@ -0,0 +1 @@
+cminusf_builder_stu.cpp
diff --git a/src/cminusfc/cminusf_builder.cpp b/src/cminusfc/cminusf_builder.cpp
index d33f33c342b5e35f3942fb7a5a8a55fc09bdcc2d..a11b279761fa95ca39a39bb75c37488072c04e3e 100644
--- a/src/cminusfc/cminusf_builder.cpp
+++ b/src/cminusfc/cminusf_builder.cpp
@@ -5,22 +5,20 @@
 
 #include "cminusf_builder.hpp"
 
-#include "logging.hpp"
-
 #define CONST_FP(num) ConstantFP::get((float)num, module.get())
 #define CONST_INT(num) ConstantInt::get(num, module.get())
 
-// TODO: Global Variable Declarations
 // You can define global variables here
-// to store state. You can expand these
-// definitions if you need to.
+// to store state
 
-// the latest return value
-Value *cur_value = nullptr;
-// if var is assignment's left part, LV is true
-bool LV = false;
+// store temporary value
+Value *tmp_val = nullptr;
+// whether require lvalue
+bool require_lvalue = false;
 // function that is being built
 Function *cur_fun = nullptr;
+// detect scope pre-enter (for elegance only)
+bool pre_enter_scope = false;
 
 // types
 Type *VOID_T;
@@ -30,9 +28,22 @@ Type *INT32PTR_T;
 Type *FLOAT_T;
 Type *FLOATPTR_T;
 
-// initializer
-ConstantZero *I32Initializer;
-ConstantZero *FloatInitializer;
+bool
+promote(IRBuilder *builder, Value **l_val_p, Value **r_val_p) {
+    bool is_int;
+    auto &l_val = *l_val_p;
+    auto &r_val = *r_val_p;
+    if (l_val->get_type() == r_val->get_type()) {
+        is_int = l_val->get_type()->is_integer_type();
+    } else {
+        is_int = false;
+        if (l_val->get_type()->is_integer_type())
+            l_val = builder->create_sitofp(l_val, FLOAT_T);
+        else
+            r_val = builder->create_sitofp(r_val, FLOAT_T);
+    }
+    return is_int;
+}
 
 /*
  * use CMinusfBuilder::Scope to construct scopes
@@ -42,182 +53,61 @@ ConstantZero *FloatInitializer;
  * scope.find: find and return the value bound to the name
  */
 
-void error_exit(std::string s) {
-    LOG_ERROR << s;
-    std::abort();
-}
-
-// This function makes sure that
-// 1. 2 values have same type
-// 2. type is either i32 or float
-void CminusfBuilder::biop_type_check(Value *&lvalue, Value *&rvalue, std::string util) {
-    if (Type::is_eq_type(lvalue->get_type(), rvalue->get_type())) {
-        if (lvalue->get_type()->is_integer_type() or lvalue->get_type()->is_float_type()) {
-            // check for i1
-            if (Type::is_eq_type(lvalue->get_type(), INT1_T)) {
-                lvalue = builder->create_zext(lvalue, INT32_T);
-                rvalue = builder->create_zext(rvalue, INT32_T);
-            }
-
-        } else
-            error_exit("not supported type cast for " + util);
-        return;
-    }
-
-    // only support cast between int and float: i32, i1, float
-    //
-    // case that integer and float is mixed, directly cast integer to float
-    if (lvalue->get_type()->is_integer_type() and rvalue->get_type()->is_float_type())
-        lvalue = builder->create_sitofp(lvalue, FLOAT_T);
-    else if (lvalue->get_type()->is_float_type() and rvalue->get_type()->is_integer_type())
-        rvalue = builder->create_sitofp(rvalue, FLOAT_T);
-    else if (lvalue->get_type()->is_integer_type() and rvalue->get_type()->is_integer_type()) {
-        // case that I32 and I1 mixed
-        if (Type::is_eq_type(lvalue->get_type(), INT1_T))
-            lvalue = builder->create_zext(lvalue, INT32_T);
-        else
-            rvalue = builder->create_zext(rvalue, INT32_T);
-    } else { // we only support computing among i1, i32 and float
-        error_exit("not supported type cast for " + util);
-    }
-}
-
-// this function makes sure value is a bool type
-void CminusfBuilder::cast_to_i1(Value *&value) {
-    assert(value->get_type()->is_integer_type() or value->get_type()->is_float_type());
-    if (value->get_type()->is_float_type())
-        // value = builder->create_fptosi(value, INT1_T);
-        value = builder->create_fcmp_ne(value, CONST_FP(0));
-    else if (Type::is_eq_type(value->get_type(), INT32_T))
-        value = builder->create_icmp_ne(value, CONST_INT(0));
-}
-
-void CminusfBuilder::visit(ASTProgram &node) {
+void
+CminusfBuilder::visit(ASTProgram &node) {
     VOID_T = Type::get_void_type(module.get());
     INT1_T = Type::get_int1_type(module.get());
     INT32_T = Type::get_int32_type(module.get());
     INT32PTR_T = Type::get_int32_ptr_type(module.get());
     FLOAT_T = Type::get_float_type(module.get());
     FLOATPTR_T = Type::get_float_ptr_type(module.get());
-    I32Initializer = ConstantZero::get(INT32_T, builder->get_module());
-    FloatInitializer = ConstantZero::get(FLOAT_T, builder->get_module());
 
     for (auto decl : node.declarations) {
         decl->accept(*this);
     }
 }
 
-// Done
-void CminusfBuilder::visit(ASTNum &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    //
-    switch (node.type) {
-        case TYPE_INT:
-            cur_value = CONST_INT(node.i_val);
-            return;
-        case TYPE_FLOAT:
-            cur_value = CONST_FP(node.f_val);
-            return;
-        default:
-            error_exit("ASTNum is not int or float");
-    }
+void
+CminusfBuilder::visit(ASTNum &node) {
+    if (node.type == TYPE_INT)
+        tmp_val = CONST_INT(node.i_val);
+    else
+        tmp_val = CONST_FP(node.f_val);
 }
 
-// Done
-void CminusfBuilder::visit(ASTVarDeclaration &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    bool global = (builder->get_insert_block() == nullptr);
-    if (node.num) {
-        // declares an array
-        //
-        // get array size
-        node.num->accept(*this);
-        //
-        // !no type cast here!
-        if (not(node.num->type == TYPE_INT))
-            error_exit("size of array has non-integer type");
-
-        int size = node.num->i_val;
-        if (size <= 0)
-            error_exit("array size[" + std::to_string(size) + "] <= 0");
-
-        switch (node.type) {
-            case TYPE_INT: {
-                auto I32Array_T = Type::get_array_type(INT32_T, size);
-                if (global)
-                    cur_value =
-                        GlobalVariable::create(node.id, builder->get_module(), I32Array_T, false, I32Initializer);
-                else
-                    cur_value = builder->create_alloca(I32Array_T);
-                break;
-            }
-
-            case TYPE_FLOAT: {
-                auto FloatArray_T = Type::get_array_type(FLOAT_T, size);
-                if (global)
-                    cur_value =
-                        GlobalVariable::create(node.id, builder->get_module(), FloatArray_T, false, FloatInitializer);
-                else
-                    cur_value = builder->create_alloca(FloatArray_T);
-                break;
-            }
-            default:
-                error_exit("Variable type(not array) is not int or float");
+void
+CminusfBuilder::visit(ASTVarDeclaration &node) {
+    Type *var_type;
+    if (node.type == TYPE_INT)
+        var_type = Type::get_int32_type(module.get());
+    else
+        var_type = Type::get_float_type(module.get());
+    if (node.num == nullptr) {
+        if (scope.in_global()) {
+            auto initializer = ConstantZero::get(var_type, module.get());
+            auto var = GlobalVariable::create(
+                node.id, module.get(), var_type, false, initializer);
+            scope.push(node.id, var);
+        } else {
+            auto var = builder->create_alloca(var_type);
+            scope.push(node.id, var);
         }
-        assert(cur_value->get_type()->is_pointer_type() && "IF SEE THIS: API ERROR");
-
     } else {
-        // flat int or float type
-        switch (node.type) {
-            case TYPE_INT:
-                if (global)
-                    cur_value = GlobalVariable::create(node.id, builder->get_module(), INT32_T, false, I32Initializer);
-                else
-                    cur_value = builder->create_alloca(INT32_T);
-                break;
-
-            case TYPE_FLOAT:
-                if (global)
-                    cur_value =
-                        GlobalVariable::create(node.id, builder->get_module(), FLOAT_T, false, FloatInitializer);
-                else {
-                    /* Beautiful is better than ugly.
-                     * Explicit is better than implicit.
-                     * Simple is better than complex.
-                     * Complex is better than complicated.
-                     * Flat is better than nested.
-                     * Sparse is better than dense.
-                     * Readability counts.
-                     * Special cases aren't special enough to break the rules.
-                     * Although practicality beats purity.
-                     * Errors should never pass silently.
-                     * Unless explicitly silenced.
-                     * In the face of ambiguity, refuse the temptation to guess.
-                     * There should be one-- and preferably only one --obvious way to do it.
-                     * Although that way may not be obvious at first unless you're Dutch.
-                     * Now is better than never.
-                     * Although never is often better than *right* now.
-                     * If the implementation is hard to explain, it's a bad idea.
-                     * If the implementation is easy to explain, it may be a good idea.
-                     * Namespaces are one honking great idea -- let's do more of those! */
-                    // cur_value = builder->create_alloca(INT32_T);
-                    cur_value = builder->create_alloca(FLOAT_T);
-                }
-                break;
-            default:
-                error_exit("Variable type(not array) is not int or float");
+        auto *array_type = ArrayType::get(var_type, node.num->i_val);
+        if (scope.in_global()) {
+            auto initializer = ConstantZero::get(array_type, module.get());
+            auto var = GlobalVariable::create(
+                node.id, module.get(), array_type, false, initializer);
+            scope.push(node.id, var);
+        } else {
+            auto var = builder->create_alloca(array_type);
+            scope.push(node.id, var);
         }
     }
-
-    if (not scope.push(node.id, cur_value))
-        error_exit("variable redefined: " + node.id);
-    LOG_DEBUG << "add entry: " << node.id << " " << cur_value;
 }
 
-// Done
-void CminusfBuilder::visit(ASTFunDeclaration &node) {
+void
+CminusfBuilder::visit(ASTFunDeclaration &node) {
     FunctionType *fun_type;
     Type *ret_type;
     std::vector<Type *> param_types;
@@ -229,46 +119,54 @@ void CminusfBuilder::visit(ASTFunDeclaration &node) {
         ret_type = VOID_T;
 
     for (auto &param : node.params) {
-        //!TODO: Please accomplish param_types.
-        //
-        // First make function BB, which needs this param type,
-        // then set_insert_point, we can call accept to gen code,
-        switch (param->type) {
-            case TYPE_INT:
-                param_types.push_back(param->isarray ? INT32PTR_T : INT32_T);
-                break;
-            case TYPE_FLOAT:
-                param_types.push_back(param->isarray ? FLOATPTR_T : FLOAT_T);
-                break;
-            case TYPE_VOID:
-                if (not param_types.empty())
-                    error_exit("function parameters weird");
-                break;
+        if (param->type == TYPE_INT) {
+            if (param->isarray) {
+                param_types.push_back(INT32PTR_T);
+            } else {
+                param_types.push_back(INT32_T);
+            }
+        } else {
+            if (param->isarray) {
+                param_types.push_back(FLOATPTR_T);
+            } else {
+                param_types.push_back(FLOAT_T);
+            }
         }
     }
 
     fun_type = FunctionType::get(ret_type, param_types);
     auto fun = Function::create(fun_type, node.id, module.get());
-    cur_fun = fun;
     scope.push(node.id, fun);
-
+    cur_fun = fun;
     auto funBB = BasicBlock::create(module.get(), "entry", fun);
     builder->set_insert_point(funBB);
     scope.enter();
-
+    pre_enter_scope = true;
     std::vector<Value *> args;
     for (auto arg = fun->arg_begin(); arg != fun->arg_end(); arg++) {
         args.push_back(*arg);
     }
-
     for (int i = 0; i < node.params.size(); ++i) {
-        //!TODO: You need to deal with params
-        // and store them in the scope.
-        cur_value = args[i];
-        node.params[i]->accept(*this);
+        if (node.params[i]->isarray) {
+            Value *array_alloc;
+            if (node.params[i]->type == TYPE_INT)
+                array_alloc = builder->create_alloca(INT32PTR_T);
+            else
+                array_alloc = builder->create_alloca(FLOATPTR_T);
+            builder->create_store(args[i], array_alloc);
+            scope.push(node.params[i]->id, array_alloc);
+        } else {
+            Value *alloc;
+            if (node.params[i]->type == TYPE_INT)
+                alloc = builder->create_alloca(INT32_T);
+            else
+                alloc = builder->create_alloca(FLOAT_T);
+            builder->create_store(args[i], alloc);
+            scope.push(node.params[i]->id, alloc);
+        }
     }
     node.compound_stmt->accept(*this);
-    // default return value
+    // can't deal with return in both blocks
     if (builder->get_insert_block()->get_terminator() == nullptr) {
         if (cur_fun->get_return_type()->is_void_type())
             builder->create_void_ret();
@@ -280,40 +178,17 @@ void CminusfBuilder::visit(ASTFunDeclaration &node) {
     scope.exit();
 }
 
-// Done
-void CminusfBuilder::visit(ASTParam &node) {
-    //!TODO: This function is empty now.
-    // If the parameter is int|float, copy and store them
-    auto param_value = cur_value;
-    switch (node.type) {
-        case TYPE_INT: {
-            if (node.isarray)
-                cur_value = builder->create_alloca(INT32PTR_T);
-            else
-                cur_value = builder->create_alloca(INT32_T);
-            break;
-        }
-        case TYPE_FLOAT: {
-            if (node.isarray)
-                cur_value = builder->create_alloca(FLOATPTR_T);
-            else
-                cur_value = builder->create_alloca(FLOAT_T);
-            break;
-        }
-        case TYPE_VOID:
-            return;
-    }
-    scope.push(node.id, cur_value);
-    builder->create_store(param_value, cur_value);
-}
+void
+CminusfBuilder::visit(ASTParam &node) {}
 
-// Done?
-void CminusfBuilder::visit(ASTCompoundStmt &node) {
-    //!TODO: This function is not complete.
-    // You may need to add some code here
-    // to deal with complex statements.
-
-    scope.enter();
+void
+CminusfBuilder::visit(ASTCompoundStmt &node) {
+    bool need_exit_scope = !pre_enter_scope;
+    if (pre_enter_scope) {
+        pre_enter_scope = false;
+    } else {
+        scope.enter();
+    }
 
     for (auto &decl : node.local_declarations) {
         decl->accept(*this);
@@ -325,413 +200,303 @@ void CminusfBuilder::visit(ASTCompoundStmt &node) {
             break;
     }
 
-    scope.exit();
+    if (need_exit_scope) {
+        scope.exit();
+    }
 }
 
-// Done
-void CminusfBuilder::visit(ASTExpressionStmt &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    if (node.expression)
+void
+CminusfBuilder::visit(ASTExpressionStmt &node) {
+    if (node.expression != nullptr)
         node.expression->accept(*this);
 }
 
-// Done
-void CminusfBuilder::visit(ASTSelectionStmt &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    scope.enter();
+void
+CminusfBuilder::visit(ASTSelectionStmt &node) {
     node.expression->accept(*this);
-    auto cond = cur_value;
-    cast_to_i1(cond);
-
-    auto ifBB = BasicBlock::create(builder->get_module(), "", cur_fun);
-    auto endBB = BasicBlock::create(builder->get_module(), "", cur_fun);
-    if (node.else_statement) {
-        auto elseBB = BasicBlock::create(builder->get_module(), "", cur_fun);
-        builder->create_cond_br(cond, ifBB, elseBB);
-
-        builder->set_insert_point(ifBB);
-        node.if_statement->accept(*this);
-        builder->create_br(endBB);
-
-        builder->set_insert_point(elseBB);
-        node.else_statement->accept(*this);
-        builder->create_br(endBB);
+    auto ret_val = tmp_val;
+    auto trueBB = BasicBlock::create(module.get(), "", cur_fun);
+    BasicBlock *falseBB{};
+    auto contBB = BasicBlock::create(module.get(), "", cur_fun);
+    Value *cond_val;
+    if (ret_val->get_type()->is_integer_type())
+        cond_val = builder->create_icmp_ne(ret_val, CONST_INT(0));
+    else
+        cond_val = builder->create_fcmp_ne(ret_val, CONST_FP(0.));
 
-        builder->set_insert_point(endBB);
+    if (node.else_statement == nullptr) {
+        builder->create_cond_br(cond_val, trueBB, contBB);
     } else {
-        builder->create_cond_br(cond, ifBB, endBB);
+        falseBB = BasicBlock::create(module.get(), "", cur_fun);
+        builder->create_cond_br(cond_val, trueBB, falseBB);
+    }
+    builder->set_insert_point(trueBB);
+    node.if_statement->accept(*this);
 
-        builder->set_insert_point(ifBB);
-        node.if_statement->accept(*this);
-        builder->create_br(endBB);
+    if (builder->get_insert_block()->get_terminator() == nullptr)
+        builder->create_br(contBB);
 
-        builder->set_insert_point(endBB);
+    if (node.else_statement == nullptr) {
+        // falseBB->erase_from_parent(); // did not clean up memory
+    } else {
+        builder->set_insert_point(falseBB);
+        node.else_statement->accept(*this);
+        if (builder->get_insert_block()->get_terminator() == nullptr)
+            builder->create_br(contBB);
     }
-    scope.exit();
-}
 
-// Done
-void CminusfBuilder::visit(ASTIterationStmt &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    scope.enter();
-    auto HEAD = BasicBlock::create(builder->get_module(), "", cur_fun);
-    auto BODY = BasicBlock::create(builder->get_module(), "", cur_fun);
-    auto END = BasicBlock::create(builder->get_module(), "", cur_fun);
-
-    builder->create_br(HEAD);
+    builder->set_insert_point(contBB);
+}
 
-    builder->set_insert_point(HEAD);
+void
+CminusfBuilder::visit(ASTIterationStmt &node) {
+    auto exprBB = BasicBlock::create(module.get(), "", cur_fun);
+    if (builder->get_insert_block()->get_terminator() == nullptr)
+        builder->create_br(exprBB);
+    builder->set_insert_point(exprBB);
     node.expression->accept(*this);
-    auto cond = cur_value;
-    cast_to_i1(cond);
-    builder->create_cond_br(cond, BODY, END);
+    auto ret_val = tmp_val;
+    auto trueBB = BasicBlock::create(module.get(), "", cur_fun);
+    auto contBB = BasicBlock::create(module.get(), "", cur_fun);
+    Value *cond_val;
+    if (ret_val->get_type()->is_integer_type())
+        cond_val = builder->create_icmp_ne(ret_val, CONST_INT(0));
+    else
+        cond_val = builder->create_fcmp_ne(ret_val, CONST_FP(0.));
 
-    builder->set_insert_point(BODY);
+    builder->create_cond_br(cond_val, trueBB, contBB);
+    builder->set_insert_point(trueBB);
     node.statement->accept(*this);
-    builder->create_br(HEAD);
-
-    builder->set_insert_point(END);
-    scope.exit();
+    if (builder->get_insert_block()->get_terminator() == nullptr)
+        builder->create_br(exprBB);
+    builder->set_insert_point(contBB);
 }
 
-// Done
-void CminusfBuilder::visit(ASTReturnStmt &node) {
+void
+CminusfBuilder::visit(ASTReturnStmt &node) {
     if (node.expression == nullptr) {
         builder->create_void_ret();
     } else {
-        //!TODO: The given code is incomplete.
-        // You need to solve other return cases (e.g. return an integer).
-        //
+        auto fun_ret_type = cur_fun->get_function_type()->get_return_type();
         node.expression->accept(*this);
-        // type cast
-        // return type can only be int, float or void
-        if (not Type::is_eq_type(cur_fun->get_return_type(), cur_value->get_type())) {
-            if (not cur_value->get_type()->is_integer_type() and not cur_value->get_type()->is_float_type())
-                error_exit("unsupported return type");
-            if (cur_value->get_type()->is_float_type())
-                cur_value = builder->create_fptosi(cur_value, INT32_T);
-            else if (cur_fun->get_return_type()->is_float_type())
-                cur_value = builder->create_sitofp(cur_value, FLOAT_T);
+        if (fun_ret_type != tmp_val->get_type()) {
+            if (fun_ret_type->is_integer_type())
+                tmp_val = builder->create_fptosi(tmp_val, INT32_T);
             else
-                cur_value = builder->create_zext(cur_value, INT32_T);
+                tmp_val = builder->create_sitofp(tmp_val, FLOAT_T);
         }
 
-        builder->create_ret(cur_value);
-        LOG_DEBUG << "create ret:\n" << builder->get_module()->print();
+        builder->create_ret(tmp_val);
     }
 }
 
-// Done
-// if LV is marked, return memory addr
-// else return value stored inside
-void CminusfBuilder::visit(ASTVar &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    //
-    // First it's pointer type, the pointed elements have 3 cases:
-    // 1. int or float
-    // 2. [i32 x n] or [float x n]
-    // 3. int*
-    auto memory = scope.find(node.id);
-    Value *addr;
-    if (memory == nullptr)
-        error_exit("variable " + node.id + " not declared");
-    LOG_DEBUG << "find entry: " << node.id << " " << memory;
-
-    assert(memory->get_type()->is_pointer_type());
-    auto element_type = memory->get_type()->get_pointer_element_type();
-
-    if (node.expression) { // e.g. int a[10]; // mem is [i32 x 10]*
-        bool old_LV = LV;
-        LV = false;
-        node.expression->accept(*this);
-        LV = old_LV;
-
-        // subscription type cast
-        if (not Type::is_eq_type(cur_value->get_type(), INT32_T)) {
-            if (Type::is_eq_type(cur_value->get_type(), FLOAT_T))
-                cur_value = builder->create_fptosi(cur_value, INT32_T);
-            else
-                error_exit("bad type for subscription");
-        }
-
-        auto cond = builder->create_icmp_lt(cur_value, CONST_INT(0));
-        auto except_func = scope.find("neg_idx_except");
-        auto TBB = BasicBlock::create(builder->get_module(), "", cur_fun);
-        auto passBB = BasicBlock::create(builder->get_module(), "", cur_fun);
-        builder->create_cond_br(cond, TBB, passBB);
-
-        builder->set_insert_point(TBB);
-        builder->create_call(except_func, {});
-        builder->create_br(passBB);
-
-        builder->set_insert_point(passBB);
-
-        // Now the subscription is in cur_value, which is good value
-        // We should focus on the var type:
-        //
-        // assert it's pointer type
-        if (element_type->is_float_type() or element_type->is_integer_type()) {
-            // 1. int or float
-            error_exit("invalid types for array subscript");
-        } else if (element_type->is_array_type()) {
-            // 2. [i32 x n] or [float x n]
-            //
-            // addr is actually &memory[0][cur_value]
-            addr = builder->create_gep(memory, {CONST_INT(0), cur_value});
-        } else if (element_type->is_pointer_type()) {
-            // 3. int*
-            // what to do:
-            // - int**->int*
-            // - seek addr
-            //
-            // addr is actually &(*memory)[cur_value]
-            addr = builder->create_load(memory);
-            addr = builder->create_gep(addr, {cur_value});
-        }
-
-        // The logic for this part is the same as `int|float` without subscription.
-        // Cause we have subscription to find the particular element(int or float),
-        // we make `addr` its memory address.
-
-    } else { // e.g. int a; // a is i32*
-        if (element_type->is_float_type() or element_type->is_integer_type()) {
-            // 1. int or float
-            // addr is the element's addr
-            addr = memory;
+void
+CminusfBuilder::visit(ASTVar &node) {
+    auto var = scope.find(node.id);
+    assert(var != nullptr);
+    auto is_int =
+        var->get_type()->get_pointer_element_type()->is_integer_type();
+    auto is_float =
+        var->get_type()->get_pointer_element_type()->is_float_type();
+    auto is_ptr =
+        var->get_type()->get_pointer_element_type()->is_pointer_type();
+    bool should_return_lvalue = require_lvalue;
+    require_lvalue = false;
+    if (node.expression == nullptr) {
+        if (should_return_lvalue) {
+            tmp_val = var;
+            require_lvalue = false;
         } else {
-            if (LV)
-                error_exit("error: pointer or array type is not assignable");
-            // For array* or pointer* type, the right-value behaviour is quite special,
-            // so treat them apart.
-            if (element_type->is_array_type()) {
-                // 2. [i32 x n] or [float x n]
-                // addr is the first element's address in the array
-                cur_value = builder->create_gep(memory, {CONST_INT(0), CONST_INT(0)});
-            } else if (element_type->is_pointer_type()) {
-                // 3. int*
-                // addr is the content in the memory, which is actually pointer type
-                cur_value = builder->create_load(memory);
+            if (is_int || is_float || is_ptr) {
+                tmp_val = builder->create_load(var);
+            } else {
+                tmp_val =
+                    builder->create_gep(var, {CONST_INT(0), CONST_INT(0)});
             }
-            return;
         }
-    }
-
-    if (LV) {
-        LOG_INFO << "directly return addr" << node.id;
-        cur_value = addr;
     } else {
-        LOG_INFO << "create load for var: " << node.id;
-        cur_value = builder->create_load(addr);
+        node.expression->accept(*this);
+        auto val = tmp_val;
+        Value *is_neg;
+        auto exceptBB = BasicBlock::create(module.get(), "", cur_fun);
+        auto contBB = BasicBlock::create(module.get(), "", cur_fun);
+        if (val->get_type()->is_float_type())
+            val = builder->create_fptosi(val, INT32_T);
+
+        is_neg = builder->create_icmp_lt(val, CONST_INT(0));
+
+        builder->create_cond_br(is_neg, exceptBB, contBB);
+        builder->set_insert_point(exceptBB);
+        auto neg_idx_except_fun = scope.find("neg_idx_except");
+        builder->create_call(static_cast<Function *>(neg_idx_except_fun), {});
+        if (cur_fun->get_return_type()->is_void_type())
+            builder->create_void_ret();
+        else if (cur_fun->get_return_type()->is_float_type())
+            builder->create_ret(CONST_FP(0.));
+        else
+            builder->create_ret(CONST_INT(0));
+
+        builder->set_insert_point(contBB);
+        Value *tmp_ptr;
+        if (is_int || is_float)
+            tmp_ptr = builder->create_gep(var, {val});
+        else if (is_ptr) {
+            auto array_load = builder->create_load(var);
+            tmp_ptr = builder->create_gep(array_load, {val});
+        } else
+            tmp_ptr = builder->create_gep(var, {CONST_INT(0), val});
+        if (should_return_lvalue) {
+            tmp_val = tmp_ptr;
+            require_lvalue = false;
+        } else {
+            tmp_val = builder->create_load(tmp_ptr);
+        }
     }
 }
 
-// Done
-void CminusfBuilder::visit(ASTAssignExpression &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    //
-    LV = true;
-    node.var->accept(*this);
-    LV = false;
-    auto addr = cur_value;
+void
+CminusfBuilder::visit(ASTAssignExpression &node) {
     node.expression->accept(*this);
-
-    assert(addr->get_type()->get_pointer_element_type() != nullptr);
-    // type cast: left is a pointer type, pointed to i32 or float
-    if (not Type::is_eq_type(addr->get_type()->get_pointer_element_type(), cur_value->get_type())) {
-        if (cur_value->get_type()->is_float_type())
-            cur_value = builder->create_fptosi(cur_value, INT32_T);
-        else if (addr->get_type()->get_pointer_element_type()->is_float_type())
-            cur_value = builder->create_sitofp(cur_value, FLOAT_T);
-        else if (Type::is_eq_type(cur_value->get_type(), INT1_T))
-            cur_value = builder->create_zext(cur_value, INT32_T);
+    auto expr_result = tmp_val;
+    require_lvalue = true;
+    node.var->accept(*this);
+    auto var_addr = tmp_val;
+    if (var_addr->get_type()->get_pointer_element_type() !=
+        expr_result->get_type()) {
+        if (expr_result->get_type() == INT32_T)
+            expr_result = builder->create_sitofp(expr_result, FLOAT_T);
         else
-            error_exit("bad type for assignment");
+            expr_result = builder->create_fptosi(expr_result, INT32_T);
     }
-    // gen code
-    builder->create_store(cur_value, addr);
+    builder->create_store(expr_result, var_addr);
+    tmp_val = expr_result;
 }
 
-// Done
-void CminusfBuilder::visit(ASTSimpleExpression &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    //
-    if (node.additive_expression_r) {
+void
+CminusfBuilder::visit(ASTSimpleExpression &node) {
+    if (node.additive_expression_r == nullptr) {
         node.additive_expression_l->accept(*this);
-        auto lvalue = cur_value;
+    } else {
+        node.additive_expression_l->accept(*this);
+        auto l_val = tmp_val;
         node.additive_expression_r->accept(*this);
-        auto rvalue = cur_value;
-        // check type
-        biop_type_check(lvalue, rvalue, "cmp");
-        bool float_cmp = lvalue->get_type()->is_float_type();
+        auto r_val = tmp_val;
+        bool is_int = promote(&*builder, &l_val, &r_val);
+        Value *cmp;
         switch (node.op) {
-            case OP_LE: {
-                if (float_cmp)
-                    cur_value = builder->create_fcmp_le(lvalue, rvalue);
+            case OP_LT:
+                if (is_int)
+                    cmp = builder->create_icmp_lt(l_val, r_val);
                 else
-                    cur_value = builder->create_icmp_le(lvalue, rvalue);
+                    cmp = builder->create_fcmp_lt(l_val, r_val);
                 break;
-            }
-            case OP_LT: {
-                if (float_cmp)
-                    cur_value = builder->create_fcmp_lt(lvalue, rvalue);
+            case OP_LE:
+                if (is_int)
+                    cmp = builder->create_icmp_le(l_val, r_val);
                 else
-                    cur_value = builder->create_icmp_lt(lvalue, rvalue);
+                    cmp = builder->create_fcmp_le(l_val, r_val);
                 break;
-            }
-            case OP_GT: {
-                if (float_cmp)
-                    cur_value = builder->create_fcmp_gt(lvalue, rvalue);
+            case OP_GE:
+                if (is_int)
+                    cmp = builder->create_icmp_ge(l_val, r_val);
                 else
-                    cur_value = builder->create_icmp_gt(lvalue, rvalue);
+                    cmp = builder->create_fcmp_ge(l_val, r_val);
                 break;
-            }
-            case OP_GE: {
-                if (float_cmp)
-                    cur_value = builder->create_fcmp_ge(lvalue, rvalue);
+            case OP_GT:
+                if (is_int)
+                    cmp = builder->create_icmp_gt(l_val, r_val);
                 else
-                    cur_value = builder->create_icmp_ge(lvalue, rvalue);
+                    cmp = builder->create_fcmp_gt(l_val, r_val);
                 break;
-            }
-            case OP_EQ: {
-                if (float_cmp)
-                    cur_value = builder->create_fcmp_eq(lvalue, rvalue);
+            case OP_EQ:
+                if (is_int)
+                    cmp = builder->create_icmp_eq(l_val, r_val);
                 else
-                    cur_value = builder->create_icmp_eq(lvalue, rvalue);
+                    cmp = builder->create_fcmp_eq(l_val, r_val);
                 break;
-            }
-            case OP_NEQ: {
-                if (float_cmp)
-                    cur_value = builder->create_fcmp_ne(lvalue, rvalue);
+            case OP_NEQ:
+                if (is_int)
+                    cmp = builder->create_icmp_ne(l_val, r_val);
                 else
-                    cur_value = builder->create_icmp_ne(lvalue, rvalue);
+                    cmp = builder->create_fcmp_ne(l_val, r_val);
                 break;
-            }
         }
-    } else
-        node.additive_expression_l->accept(*this);
+
+        tmp_val = builder->create_zext(cmp, INT32_T);
+    }
 }
 
-// Done
-void CminusfBuilder::visit(ASTAdditiveExpression &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    //
-    if (node.additive_expression) {
+void
+CminusfBuilder::visit(ASTAdditiveExpression &node) {
+    if (node.additive_expression == nullptr) {
+        node.term->accept(*this);
+    } else {
         node.additive_expression->accept(*this);
-        auto lvalue = cur_value;
+        auto l_val = tmp_val;
         node.term->accept(*this);
-        auto rvalue = cur_value;
-        // check type
-        biop_type_check(lvalue, rvalue, "addop");
-        bool float_type = lvalue->get_type()->is_float_type();
-        // now left and right is the same type
+        auto r_val = tmp_val;
+        bool is_int = promote(&*builder, &l_val, &r_val);
         switch (node.op) {
-            case OP_PLUS: {
-                if (float_type)
-                    cur_value = builder->create_fadd(lvalue, rvalue);
+            case OP_PLUS:
+                if (is_int)
+                    tmp_val = builder->create_iadd(l_val, r_val);
                 else
-                    cur_value = builder->create_iadd(lvalue, rvalue);
+                    tmp_val = builder->create_fadd(l_val, r_val);
                 break;
-            }
-            case OP_MINUS: {
-                if (float_type)
-                    cur_value = builder->create_fsub(lvalue, rvalue);
+            case OP_MINUS:
+                if (is_int)
+                    tmp_val = builder->create_isub(l_val, r_val);
                 else
-                    cur_value = builder->create_isub(lvalue, rvalue);
+                    tmp_val = builder->create_fsub(l_val, r_val);
                 break;
-            }
         }
-    } else
-        node.term->accept(*this);
+    }
 }
 
-// Done
-void CminusfBuilder::visit(ASTTerm &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    if (node.term) {
+void
+CminusfBuilder::visit(ASTTerm &node) {
+    if (node.term == nullptr) {
+        node.factor->accept(*this);
+    } else {
         node.term->accept(*this);
-        auto lvalue = cur_value;
+        auto l_val = tmp_val;
         node.factor->accept(*this);
-        auto rvalue = cur_value;
-        // check type
-        biop_type_check(lvalue, rvalue, "mul");
-        bool float_type = lvalue->get_type()->is_float_type();
-        // now left and right is the same type
+        auto r_val = tmp_val;
+        bool is_int = promote(&*builder, &l_val, &r_val);
         switch (node.op) {
-            case OP_MUL: {
-                if (float_type)
-                    cur_value = builder->create_fmul(lvalue, rvalue);
+            case OP_MUL:
+                if (is_int)
+                    tmp_val = builder->create_imul(l_val, r_val);
                 else
-                    cur_value = builder->create_imul(lvalue, rvalue);
+                    tmp_val = builder->create_fmul(l_val, r_val);
                 break;
-            }
-            case OP_DIV: {
-                if (float_type)
-                    cur_value = builder->create_fdiv(lvalue, rvalue);
+            case OP_DIV:
+                if (is_int)
+                    tmp_val = builder->create_isdiv(l_val, r_val);
                 else
-                    cur_value = builder->create_isdiv(lvalue, rvalue);
+                    tmp_val = builder->create_fdiv(l_val, r_val);
                 break;
-            }
         }
-    } else
-        node.factor->accept(*this);
+    }
 }
 
-// Done
-void CminusfBuilder::visit(ASTCall &node) {
-    //!TODO: This function is empty now.
-    // Add some code here.
-    Function *func = static_cast<Function *>(scope.find(node.id));
+void
+CminusfBuilder::visit(ASTCall &node) {
+    auto fun = static_cast<Function *>(scope.find(node.id));
     std::vector<Value *> args;
-    if (func == nullptr)
-        error_exit("function " + node.id + " not declared");
-    if (node.args.size() != func->get_num_of_args())
-        error_exit("expect " + std::to_string(func->get_num_of_args()) + " params, but " +
-                   std::to_string(node.args.size()) + " is given");
-    // check every argument
-    for (int i = 0; i != node.args.size(); ++i) {
-        // ith parameter's type
-        Type *param_type = func->get_function_type()->get_param_type(i);
-        node.args[i]->accept(*this);
-
-        // type cast
-        if (not Type::is_eq_type(param_type, cur_value->get_type())) {
-            if (param_type->is_pointer_type()) {
-                // shouldn't need type cast for pointer, logically
-                if (param_type->get_pointer_element_type()->is_integer_type() or
-                    param_type->get_pointer_element_type()->is_float_type())
-                    error_exit("BUG HERE: ASTVar return value is not int* or float*");
-                else
-                    error_exit("BUG HERE: function param needs weird pointer type");
-
-            } else if (param_type->is_integer_type() or param_type->is_float_type()) {
-                // need type cast between int and float
-                if (not cur_value->get_type()->is_integer_type() and not cur_value->get_type()->is_float_type())
-                    error_exit("unexpected type cast!");
-
-                if (param_type->is_float_type())
-                    cur_value = builder->create_sitofp(cur_value, FLOAT_T);
-                else if (param_type->is_integer_type())
-                    if (cur_value->get_type()->is_integer_type())
-                        cur_value = builder->create_zext(cur_value, INT32_T);
-                    else
-                        cur_value = builder->create_fptosi(cur_value, INT32_T);
-                else
-                    error_exit("unexpected type cast!");
-
-            } else
-                error_exit("unexpected case when casting arguments for function call " + node.id);
+    auto param_type = fun->get_function_type()->param_begin();
+    for (auto &arg : node.args) {
+        arg->accept(*this);
+        if (!tmp_val->get_type()->is_pointer_type() &&
+            *param_type != tmp_val->get_type()) {
+            if (tmp_val->get_type()->is_integer_type())
+                tmp_val = builder->create_sitofp(tmp_val, FLOAT_T);
+            else
+                tmp_val = builder->create_fptosi(tmp_val, INT32_T);
         }
-
-        // now cur_value fits the param type
-        args.push_back(cur_value);
+        args.push_back(tmp_val);
+        param_type++;
     }
-    cur_value = builder->create_call(func, args);
+
+    tmp_val = builder->create_call(static_cast<Function *>(fun), args);
 }
diff --git a/src/lightir/Instruction.cpp b/src/lightir/Instruction.cpp
index e4cd6cd4c361c9f5f1e322e8274998fe5f2a3fcf..9eb9dcde10662a36a8340a75d68d12a6190d4baa 100644
--- a/src/lightir/Instruction.cpp
+++ b/src/lightir/Instruction.cpp
@@ -10,7 +10,10 @@
 #include <cassert>
 #include <vector>
 
-Instruction::Instruction(Type *ty, OpID id, unsigned num_ops, BasicBlock *parent)
+Instruction::Instruction(Type *ty,
+                         OpID id,
+                         unsigned num_ops,
+                         BasicBlock *parent)
     : User(ty, "", num_ops), op_id_(id), num_ops_(num_ops), parent_(parent) {
     parent_->add_instruction(this);
 }
@@ -18,56 +21,75 @@ Instruction::Instruction(Type *ty, OpID id, unsigned num_ops, BasicBlock *parent
 Instruction::Instruction(Type *ty, OpID id, unsigned num_ops)
     : User(ty, "", num_ops), op_id_(id), num_ops_(num_ops), parent_(nullptr) {}
 
-Function *Instruction::get_function() { return parent_->get_parent(); }
+Function *
+Instruction::get_function() {
+    return parent_->get_parent();
+}
 
-Module *Instruction::get_module() { return parent_->get_module(); }
+Module *
+Instruction::get_module() {
+    return parent_->get_module();
+}
 
-BinaryInst::BinaryInst(Type *ty, OpID id, Value *v1, Value *v2, BasicBlock *bb) : BaseInst<BinaryInst>(ty, id, 2, bb) {
+BinaryInst::BinaryInst(Type *ty, OpID id, Value *v1, Value *v2, BasicBlock *bb)
+    : BaseInst<BinaryInst>(ty, id, 2, bb) {
     set_operand(0, v1);
     set_operand(1, v2);
     // assertValid();
 }
 
-void BinaryInst::assertValid() {
+void
+BinaryInst::assertValid() {
     assert(get_operand(0)->get_type()->is_integer_type());
     assert(get_operand(1)->get_type()->is_integer_type());
-    assert(static_cast<IntegerType *>(get_operand(0)->get_type())->get_num_bits() ==
-           static_cast<IntegerType *>(get_operand(1)->get_type())->get_num_bits());
+    assert(
+        static_cast<IntegerType *>(get_operand(0)->get_type())
+            ->get_num_bits() ==
+        static_cast<IntegerType *>(get_operand(1)->get_type())->get_num_bits());
 }
 
-BinaryInst *BinaryInst::create_add(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_add(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_int32_type(m), Instruction::add, v1, v2, bb);
 }
 
-BinaryInst *BinaryInst::create_sub(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_sub(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_int32_type(m), Instruction::sub, v1, v2, bb);
 }
 
-BinaryInst *BinaryInst::create_mul(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_mul(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_int32_type(m), Instruction::mul, v1, v2, bb);
 }
 
-BinaryInst *BinaryInst::create_sdiv(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_sdiv(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_int32_type(m), Instruction::sdiv, v1, v2, bb);
 }
 
-BinaryInst *BinaryInst::create_fadd(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_fadd(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_float_type(m), Instruction::fadd, v1, v2, bb);
 }
 
-BinaryInst *BinaryInst::create_fsub(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_fsub(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_float_type(m), Instruction::fsub, v1, v2, bb);
 }
 
-BinaryInst *BinaryInst::create_fmul(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_fmul(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_float_type(m), Instruction::fmul, v1, v2, bb);
 }
 
-BinaryInst *BinaryInst::create_fdiv(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
+BinaryInst *
+BinaryInst::create_fdiv(Value *v1, Value *v2, BasicBlock *bb, Module *m) {
     return create(Type::get_float_type(m), Instruction::fdiv, v1, v2, bb);
 }
 
-std::string BinaryInst::print() {
+std::string
+BinaryInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -78,7 +100,8 @@ std::string BinaryInst::print() {
     instr_ir += " ";
     instr_ir += print_as_op(this->get_operand(0), false);
     instr_ir += ", ";
-    if (Type::is_eq_type(this->get_operand(0)->get_type(), this->get_operand(1)->get_type())) {
+    if (Type::is_eq_type(this->get_operand(0)->get_type(),
+                         this->get_operand(1)->get_type())) {
         instr_ir += print_as_op(this->get_operand(1), false);
     } else {
         instr_ir += print_as_op(this->get_operand(1), true);
@@ -93,18 +116,27 @@ CmpInst::CmpInst(Type *ty, CmpOp op, Value *lhs, Value *rhs, BasicBlock *bb)
     // assertValid();
 }
 
-void CmpInst::assertValid() {
+void
+CmpInst::assertValid() {
     assert(get_operand(0)->get_type()->is_integer_type());
     assert(get_operand(1)->get_type()->is_integer_type());
-    assert(static_cast<IntegerType *>(get_operand(0)->get_type())->get_num_bits() ==
-           static_cast<IntegerType *>(get_operand(1)->get_type())->get_num_bits());
-}
-
-CmpInst *CmpInst::create_cmp(CmpOp op, Value *lhs, Value *rhs, BasicBlock *bb, Module *m) {
+    assert(
+        static_cast<IntegerType *>(get_operand(0)->get_type())
+            ->get_num_bits() ==
+        static_cast<IntegerType *>(get_operand(1)->get_type())->get_num_bits());
+}
+
+CmpInst *
+CmpInst::create_cmp(CmpOp op,
+                    Value *lhs,
+                    Value *rhs,
+                    BasicBlock *bb,
+                    Module *m) {
     return create(m->get_int1_type(), op, lhs, rhs, bb);
 }
 
-std::string CmpInst::print() {
+std::string
+CmpInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -117,7 +149,8 @@ std::string CmpInst::print() {
     instr_ir += " ";
     instr_ir += print_as_op(this->get_operand(0), false);
     instr_ir += ", ";
-    if (Type::is_eq_type(this->get_operand(0)->get_type(), this->get_operand(1)->get_type())) {
+    if (Type::is_eq_type(this->get_operand(0)->get_type(),
+                         this->get_operand(1)->get_type())) {
         instr_ir += print_as_op(this->get_operand(1), false);
     } else {
         instr_ir += print_as_op(this->get_operand(1), true);
@@ -132,16 +165,23 @@ FCmpInst::FCmpInst(Type *ty, CmpOp op, Value *lhs, Value *rhs, BasicBlock *bb)
     // assertValid();
 }
 
-void FCmpInst::assert_valid() {
+void
+FCmpInst::assert_valid() {
     assert(get_operand(0)->get_type()->is_float_type());
     assert(get_operand(1)->get_type()->is_float_type());
 }
 
-FCmpInst *FCmpInst::create_fcmp(CmpOp op, Value *lhs, Value *rhs, BasicBlock *bb, Module *m) {
+FCmpInst *
+FCmpInst::create_fcmp(CmpOp op,
+                      Value *lhs,
+                      Value *rhs,
+                      BasicBlock *bb,
+                      Module *m) {
     return create(m->get_int1_type(), op, lhs, rhs, bb);
 }
 
-std::string FCmpInst::print() {
+std::string
+FCmpInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -154,7 +194,8 @@ std::string FCmpInst::print() {
     instr_ir += " ";
     instr_ir += print_as_op(this->get_operand(0), false);
     instr_ir += ",";
-    if (Type::is_eq_type(this->get_operand(0)->get_type(), this->get_operand(1)->get_type())) {
+    if (Type::is_eq_type(this->get_operand(0)->get_type(),
+                         this->get_operand(1)->get_type())) {
         instr_ir += print_as_op(this->get_operand(1), false);
     } else {
         instr_ir += print_as_op(this->get_operand(1), true);
@@ -163,7 +204,10 @@ std::string FCmpInst::print() {
 }
 
 CallInst::CallInst(Function *func, std::vector<Value *> args, BasicBlock *bb)
-    : BaseInst<CallInst>(func->get_return_type(), Instruction::call, args.size() + 1, bb) {
+    : BaseInst<CallInst>(func->get_return_type(),
+                         Instruction::call,
+                         args.size() + 1,
+                         bb) {
     assert(func->get_num_of_args() == args.size());
     int num_ops = args.size() + 1;
     set_operand(0, func);
@@ -172,13 +216,18 @@ CallInst::CallInst(Function *func, std::vector<Value *> args, BasicBlock *bb)
     }
 }
 
-CallInst *CallInst::create(Function *func, std::vector<Value *> args, BasicBlock *bb) {
+CallInst *
+CallInst::create(Function *func, std::vector<Value *> args, BasicBlock *bb) {
     return BaseInst<CallInst>::create(func, args, bb);
 }
 
-FunctionType *CallInst::get_function_type() const { return static_cast<FunctionType *>(get_operand(0)->get_type()); }
+FunctionType *
+CallInst::get_function_type() const {
+    return static_cast<FunctionType *>(get_operand(0)->get_type());
+}
 
-std::string CallInst::print() {
+std::string
+CallInst::print() {
     std::string instr_ir;
     if (!this->is_void()) {
         instr_ir += "%";
@@ -190,7 +239,8 @@ std::string CallInst::print() {
     instr_ir += this->get_function_type()->get_return_type()->print();
 
     instr_ir += " ";
-    assert(dynamic_cast<Function *>(this->get_operand(0)) && "Wrong call operand function");
+    assert(dynamic_cast<Function *>(this->get_operand(0)) &&
+           "Wrong call operand function");
     instr_ir += print_as_op(this->get_operand(0), false);
     instr_ir += "(";
     for (int i = 1; i < this->get_num_operand(); i++) {
@@ -204,19 +254,32 @@ std::string CallInst::print() {
     return instr_ir;
 }
 
-BranchInst::BranchInst(Value *cond, BasicBlock *if_true, BasicBlock *if_false, BasicBlock *bb)
-    : BaseInst<BranchInst>(Type::get_void_type(if_true->get_module()), Instruction::br, 3, bb) {
+BranchInst::BranchInst(Value *cond,
+                       BasicBlock *if_true,
+                       BasicBlock *if_false,
+                       BasicBlock *bb)
+    : BaseInst<BranchInst>(Type::get_void_type(if_true->get_module()),
+                           Instruction::br,
+                           3,
+                           bb) {
     set_operand(0, cond);
     set_operand(1, if_true);
     set_operand(2, if_false);
 }
 
 BranchInst::BranchInst(BasicBlock *if_true, BasicBlock *bb)
-    : BaseInst<BranchInst>(Type::get_void_type(if_true->get_module()), Instruction::br, 1, bb) {
+    : BaseInst<BranchInst>(Type::get_void_type(if_true->get_module()),
+                           Instruction::br,
+                           1,
+                           bb) {
     set_operand(0, if_true);
 }
 
-BranchInst *BranchInst::create_cond_br(Value *cond, BasicBlock *if_true, BasicBlock *if_false, BasicBlock *bb) {
+BranchInst *
+BranchInst::create_cond_br(Value *cond,
+                           BasicBlock *if_true,
+                           BasicBlock *if_false,
+                           BasicBlock *bb) {
     if_true->add_pre_basic_block(bb);
     if_false->add_pre_basic_block(bb);
     bb->add_succ_basic_block(if_false);
@@ -225,16 +288,21 @@ BranchInst *BranchInst::create_cond_br(Value *cond, BasicBlock *if_true, BasicBl
     return create(cond, if_true, if_false, bb);
 }
 
-BranchInst *BranchInst::create_br(BasicBlock *if_true, BasicBlock *bb) {
+BranchInst *
+BranchInst::create_br(BasicBlock *if_true, BasicBlock *bb) {
     if_true->add_pre_basic_block(bb);
     bb->add_succ_basic_block(if_true);
 
     return create(if_true, bb);
 }
 
-bool BranchInst::is_cond_br() const { return get_num_operand() == 3; }
+bool
+BranchInst::is_cond_br() const {
+    return get_num_operand() == 3;
+}
 
-std::string BranchInst::print() {
+std::string
+BranchInst::print() {
     std::string instr_ir;
     instr_ir += this->get_module()->get_instr_op_name(this->get_instr_type());
     instr_ir += " ";
@@ -250,20 +318,36 @@ std::string BranchInst::print() {
 }
 
 ReturnInst::ReturnInst(Value *val, BasicBlock *bb)
-    : BaseInst<ReturnInst>(Type::get_void_type(bb->get_module()), Instruction::ret, 1, bb) {
+    : BaseInst<ReturnInst>(Type::get_void_type(bb->get_module()),
+                           Instruction::ret,
+                           1,
+                           bb) {
     set_operand(0, val);
 }
 
 ReturnInst::ReturnInst(BasicBlock *bb)
-    : BaseInst<ReturnInst>(Type::get_void_type(bb->get_module()), Instruction::ret, 0, bb) {}
+    : BaseInst<ReturnInst>(Type::get_void_type(bb->get_module()),
+                           Instruction::ret,
+                           0,
+                           bb) {}
 
-ReturnInst *ReturnInst::create_ret(Value *val, BasicBlock *bb) { return create(val, bb); }
+ReturnInst *
+ReturnInst::create_ret(Value *val, BasicBlock *bb) {
+    return create(val, bb);
+}
 
-ReturnInst *ReturnInst::create_void_ret(BasicBlock *bb) { return create(bb); }
+ReturnInst *
+ReturnInst::create_void_ret(BasicBlock *bb) {
+    return create(bb);
+}
 
-bool ReturnInst::is_void_ret() const { return get_num_operand() == 0; }
+bool
+ReturnInst::is_void_ret() const {
+    return get_num_operand() == 0;
+}
 
-std::string ReturnInst::print() {
+std::string
+ReturnInst::print() {
     std::string instr_ir;
     instr_ir += this->get_module()->get_instr_op_name(this->get_instr_type());
     instr_ir += " ";
@@ -278,7 +362,9 @@ std::string ReturnInst::print() {
     return instr_ir;
 }
 
-GetElementPtrInst::GetElementPtrInst(Value *ptr, std::vector<Value *> idxs, BasicBlock *bb)
+GetElementPtrInst::GetElementPtrInst(Value *ptr,
+                                     std::vector<Value *> idxs,
+                                     BasicBlock *bb)
     : BaseInst<GetElementPtrInst>(PointerType::get(get_element_type(ptr, idxs)),
                                   Instruction::getelementptr,
                                   1 + idxs.size(),
@@ -290,10 +376,12 @@ GetElementPtrInst::GetElementPtrInst(Value *ptr, std::vector<Value *> idxs, Basi
     element_ty_ = get_element_type(ptr, idxs);
 }
 
-Type *GetElementPtrInst::get_element_type(Value *ptr, std::vector<Value *> idxs) {
+Type *
+GetElementPtrInst::get_element_type(Value *ptr, std::vector<Value *> idxs) {
     Type *ty = ptr->get_type()->get_pointer_element_type();
-    assert("GetElementPtrInst ptr is wrong type" &&
-           (ty->is_array_type() || ty->is_integer_type() || ty->is_float_type()));
+    assert(
+        "GetElementPtrInst ptr is wrong type" &&
+        (ty->is_array_type() || ty->is_integer_type() || ty->is_float_type()));
     if (ty->is_array_type()) {
         ArrayType *arr_ty = static_cast<ArrayType *>(ty);
         for (int i = 1; i < idxs.size(); i++) {
@@ -309,13 +397,20 @@ Type *GetElementPtrInst::get_element_type(Value *ptr, std::vector<Value *> idxs)
     return ty;
 }
 
-Type *GetElementPtrInst::get_element_type() const { return element_ty_; }
+Type *
+GetElementPtrInst::get_element_type() const {
+    return element_ty_;
+}
 
-GetElementPtrInst *GetElementPtrInst::create_gep(Value *ptr, std::vector<Value *> idxs, BasicBlock *bb) {
+GetElementPtrInst *
+GetElementPtrInst::create_gep(Value *ptr,
+                              std::vector<Value *> idxs,
+                              BasicBlock *bb) {
     return create(ptr, idxs, bb);
 }
 
-std::string GetElementPtrInst::print() {
+std::string
+GetElementPtrInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -323,7 +418,8 @@ std::string GetElementPtrInst::print() {
     instr_ir += this->get_module()->get_instr_op_name(this->get_instr_type());
     instr_ir += " ";
     assert(this->get_operand(0)->get_type()->is_pointer_type());
-    instr_ir += this->get_operand(0)->get_type()->get_pointer_element_type()->print();
+    instr_ir +=
+        this->get_operand(0)->get_type()->get_pointer_element_type()->print();
     instr_ir += ", ";
     for (int i = 0; i < this->get_num_operand(); i++) {
         if (i > 0)
@@ -336,14 +432,21 @@ std::string GetElementPtrInst::print() {
 }
 
 StoreInst::StoreInst(Value *val, Value *ptr, BasicBlock *bb)
-    : BaseInst<StoreInst>(Type::get_void_type(bb->get_module()), Instruction::store, 2, bb) {
+    : BaseInst<StoreInst>(Type::get_void_type(bb->get_module()),
+                          Instruction::store,
+                          2,
+                          bb) {
     set_operand(0, val);
     set_operand(1, ptr);
 }
 
-StoreInst *StoreInst::create_store(Value *val, Value *ptr, BasicBlock *bb) { return create(val, ptr, bb); }
+StoreInst *
+StoreInst::create_store(Value *val, Value *ptr, BasicBlock *bb) {
+    return create(val, ptr, bb);
+}
 
-std::string StoreInst::print() {
+std::string
+StoreInst::print() {
     std::string instr_ir;
     instr_ir += this->get_module()->get_instr_op_name(this->get_instr_type());
     instr_ir += " ";
@@ -355,19 +458,27 @@ std::string StoreInst::print() {
     return instr_ir;
 }
 
-LoadInst::LoadInst(Type *ty, Value *ptr, BasicBlock *bb) : BaseInst<LoadInst>(ty, Instruction::load, 1, bb) {
+LoadInst::LoadInst(Type *ty, Value *ptr, BasicBlock *bb)
+    : BaseInst<LoadInst>(ty, Instruction::load, 1, bb) {
     assert(ptr->get_type()->is_pointer_type());
-    assert(ty == static_cast<PointerType *>(ptr->get_type())->get_element_type());
+    assert(ty ==
+           static_cast<PointerType *>(ptr->get_type())->get_element_type());
     set_operand(0, ptr);
 }
 
-LoadInst *LoadInst::create_load(Type *ty, Value *ptr, BasicBlock *bb) { return create(ty, ptr, bb); }
+LoadInst *
+LoadInst::create_load(Type *ty, Value *ptr, BasicBlock *bb) {
+    return create(ty, ptr, bb);
+}
 
-Type *LoadInst::get_load_type() const {
-    return static_cast<PointerType *>(get_operand(0)->get_type())->get_element_type();
+Type *
+LoadInst::get_load_type() const {
+    return static_cast<PointerType *>(get_operand(0)->get_type())
+        ->get_element_type();
 }
 
-std::string LoadInst::print() {
+std::string
+LoadInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -375,7 +486,8 @@ std::string LoadInst::print() {
     instr_ir += this->get_module()->get_instr_op_name(this->get_instr_type());
     instr_ir += " ";
     assert(this->get_operand(0)->get_type()->is_pointer_type());
-    instr_ir += this->get_operand(0)->get_type()->get_pointer_element_type()->print();
+    instr_ir +=
+        this->get_operand(0)->get_type()->get_pointer_element_type()->print();
     instr_ir += ",";
     instr_ir += " ";
     instr_ir += print_as_op(this->get_operand(0), true);
@@ -383,13 +495,21 @@ std::string LoadInst::print() {
 }
 
 AllocaInst::AllocaInst(Type *ty, BasicBlock *bb)
-    : BaseInst<AllocaInst>(PointerType::get(ty), Instruction::alloca, 0, bb), alloca_ty_(ty) {}
+    : BaseInst<AllocaInst>(PointerType::get(ty), Instruction::alloca, 0, bb)
+    , alloca_ty_(ty) {}
 
-AllocaInst *AllocaInst::create_alloca(Type *ty, BasicBlock *bb) { return create(ty, bb); }
+AllocaInst *
+AllocaInst::create_alloca(Type *ty, BasicBlock *bb) {
+    return create(ty, bb);
+}
 
-Type *AllocaInst::get_alloca_type() const { return alloca_ty_; }
+Type *
+AllocaInst::get_alloca_type() const {
+    return alloca_ty_;
+}
 
-std::string AllocaInst::print() {
+std::string
+AllocaInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -400,15 +520,23 @@ std::string AllocaInst::print() {
     return instr_ir;
 }
 
-ZextInst::ZextInst(OpID op, Value *val, Type *ty, BasicBlock *bb) : BaseInst<ZextInst>(ty, op, 1, bb), dest_ty_(ty) {
+ZextInst::ZextInst(OpID op, Value *val, Type *ty, BasicBlock *bb)
+    : BaseInst<ZextInst>(ty, op, 1, bb), dest_ty_(ty) {
     set_operand(0, val);
 }
 
-ZextInst *ZextInst::create_zext(Value *val, Type *ty, BasicBlock *bb) { return create(Instruction::zext, val, ty, bb); }
+ZextInst *
+ZextInst::create_zext(Value *val, Type *ty, BasicBlock *bb) {
+    return create(Instruction::zext, val, ty, bb);
+}
 
-Type *ZextInst::get_dest_type() const { return dest_ty_; }
+Type *
+ZextInst::get_dest_type() const {
+    return dest_ty_;
+}
 
-std::string ZextInst::print() {
+std::string
+ZextInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -428,13 +556,18 @@ FpToSiInst::FpToSiInst(OpID op, Value *val, Type *ty, BasicBlock *bb)
     set_operand(0, val);
 }
 
-FpToSiInst *FpToSiInst::create_fptosi(Value *val, Type *ty, BasicBlock *bb) {
+FpToSiInst *
+FpToSiInst::create_fptosi(Value *val, Type *ty, BasicBlock *bb) {
     return create(Instruction::fptosi, val, ty, bb);
 }
 
-Type *FpToSiInst::get_dest_type() const { return dest_ty_; }
+Type *
+FpToSiInst::get_dest_type() const {
+    return dest_ty_;
+}
 
-std::string FpToSiInst::print() {
+std::string
+FpToSiInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -454,13 +587,18 @@ SiToFpInst::SiToFpInst(OpID op, Value *val, Type *ty, BasicBlock *bb)
     set_operand(0, val);
 }
 
-SiToFpInst *SiToFpInst::create_sitofp(Value *val, Type *ty, BasicBlock *bb) {
+SiToFpInst *
+SiToFpInst::create_sitofp(Value *val, Type *ty, BasicBlock *bb) {
     return create(Instruction::sitofp, val, ty, bb);
 }
 
-Type *SiToFpInst::get_dest_type() const { return dest_ty_; }
+Type *
+SiToFpInst::get_dest_type() const {
+    return dest_ty_;
+}
 
-std::string SiToFpInst::print() {
+std::string
+SiToFpInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -475,7 +613,11 @@ std::string SiToFpInst::print() {
     return instr_ir;
 }
 
-PhiInst::PhiInst(OpID op, std::vector<Value *> vals, std::vector<BasicBlock *> val_bbs, Type *ty, BasicBlock *bb)
+PhiInst::PhiInst(OpID op,
+                 std::vector<Value *> vals,
+                 std::vector<BasicBlock *> val_bbs,
+                 Type *ty,
+                 BasicBlock *bb)
     : BaseInst<PhiInst>(ty, op, 2 * vals.size()) {
     for (int i = 0; i < vals.size(); i++) {
         set_operand(2 * i, vals[i]);
@@ -484,13 +626,15 @@ PhiInst::PhiInst(OpID op, std::vector<Value *> vals, std::vector<BasicBlock *> v
     this->set_parent(bb);
 }
 
-PhiInst *PhiInst::create_phi(Type *ty, BasicBlock *bb) {
+PhiInst *
+PhiInst::create_phi(Type *ty, BasicBlock *bb) {
     std::vector<Value *> vals;
     std::vector<BasicBlock *> val_bbs;
     return create(Instruction::phi, vals, val_bbs, ty, bb);
 }
 
-std::string PhiInst::print() {
+std::string
+PhiInst::print() {
     std::string instr_ir;
     instr_ir += "%";
     instr_ir += this->get_name();
@@ -508,9 +652,12 @@ std::string PhiInst::print() {
         instr_ir += print_as_op(this->get_operand(2 * i + 1), false);
         instr_ir += " ]";
     }
-    if (this->get_num_operand() / 2 < this->get_parent()->get_pre_basic_blocks().size()) {
+    if (this->get_num_operand() / 2 <
+        this->get_parent()->get_pre_basic_blocks().size()) {
         for (auto pre_bb : this->get_parent()->get_pre_basic_blocks()) {
-            if (std::find(this->get_operands().begin(), this->get_operands().end(), static_cast<Value *>(pre_bb)) ==
+            if (std::find(this->get_operands().begin(),
+                          this->get_operands().end(),
+                          static_cast<Value *>(pre_bb)) ==
                 this->get_operands().end()) {
                 // find a pre_bb is not in phi
                 instr_ir += ", [ undef, " + print_as_op(pre_bb, false) + " ]";
diff --git a/src/optimization/GVN.cpp b/src/optimization/GVN.cpp
index 5f76ab405010d1a57629ed21d7bb60a2f386110b..db437dc140b4feb1293064570958229f68c46307 100644
--- a/src/optimization/GVN.cpp
+++ b/src/optimization/GVN.cpp
@@ -209,6 +209,17 @@ print_partitions(const GVN::partitions &p) {
 }
 } // namespace utils
 
+GVN::partitions
+GVN::join_helper(BasicBlock *pre1, BasicBlock *pre2) {
+    assert(not _TOP[pre1] or not _TOP[pre2] && "should flow here, not jump");
+
+    if (_TOP[pre1])
+        return pout_[pre2];
+    else if (_TOP[pre2])
+        return pout_[pre1];
+    return join(pout_[pre1], pout_[pre2]);
+}
+
 GVN::partitions
 GVN::join(const partitions &P1, const partitions &P2) {
     // TODO: do intersection pair-wise
@@ -228,7 +239,6 @@ std::shared_ptr<CongruenceClass>
 GVN::intersect(std::shared_ptr<CongruenceClass> ci,
                std::shared_ptr<CongruenceClass> cj) {
     // TODO
-    // If no common members, return null
     auto c = createCongruenceClass();
     std::set<Value *> intersection;
 
@@ -240,10 +250,21 @@ GVN::intersect(std::shared_ptr<CongruenceClass> ci,
     c->members_ = intersection;
     if (ci->index_ == cj->index_)
         c->index_ = ci->index_;
-    if (ci->leader_ == cj->leader_)
-        c->leader_ = cj->leader_;
-    /* if (*ci == *cj)
-     *     return ci; */
+    if (ci->value_expr_ == cj->value_expr_)
+        c->value_expr_ = ci->value_expr_;
+    if (ci->value_phi_ and cj->value_phi_ and
+        *ci->value_phi_ == *cj->value_phi_)
+        c->value_phi_ = ci->value_phi_;
+
+    // if (c->members_.size() or c->value_expr_ or c->value_phi_) // not empty
+    // ??
+    // What if the ve is nullptr?
+    if (c->members_.size()) // not empty
+        if (c->index_ == 0) {
+            c->index_ = new_number();
+            c->value_phi_ =
+                PhiExpression::create(ci->value_expr_, cj->value_expr_);
+        }
 
     return c;
 }
@@ -251,30 +272,31 @@ GVN::intersect(std::shared_ptr<CongruenceClass> ci,
 void
 GVN::detectEquivalences() {
     bool changed;
+    std::cout << "all the instruction address:" << std::endl;
+    for (auto &bb : func_->get_basic_blocks()) {
+        for (auto &instr : bb.get_instructions())
+            std::cout << &instr << "\t" << instr.print() << std::endl;
+    } 
 
     // initialize pout with top
     for (auto &bb : func_->get_basic_blocks()) {
-        // pin_[&bb].clear();
-        // pout_[&bb].clear();
-        for (auto &instr : bb.get_instructions())
-            _TOP[&instr] = true;
+        _TOP[&bb] = true;
     }
 
-    // modify entry block
     auto Entry = func_->get_entry_block();
-    _TOP[&*Entry->get_instructions().begin()] = false;
+    _TOP[Entry] = false;
+
     pin_[Entry].clear();
-    pout_[Entry].clear(); // pout_[Entry] = transferFunction(Entry);
+    pout_[Entry] = transferFunction(Entry);
 
     // iterate until converge
     do {
         changed = false;
-        // see the pseudo code in documentation
-        for (auto &_bb :
-             func_->get_basic_blocks()) { // you might need to visit the
-                                          // blocks in depth-first order
+        for (auto &_bb : func_->get_basic_blocks()) {
             auto bb = &_bb;
-            // get PIN of bb by predecessor(s)
+            if (bb == Entry)
+                continue;
+            // get PIN of bb from predecessor(s)
             auto pre_bbs_ = bb->get_pre_basic_blocks();
             if (bb != Entry) {
                 // only update PIN for blocks that are not Entry
@@ -283,12 +305,12 @@ GVN::detectEquivalences() {
                     case 2: {
                         auto pre_1 = *pre_bbs_.begin();
                         auto pre_2 = *(++pre_bbs_.begin());
-                        pin_[bb] = join(pin_[pre_1], pin_[pre_2]);
+                        pin_[bb] = join_helper(pre_1, pre_2);
                         break;
                     }
                     case 1: {
                         auto pre = *(pre_bbs_.begin());
-                        pin_[bb] = clone(pin_[pre]);
+                        pin_[bb] = pout_[pre];
                         break;
                     }
                     default:
@@ -297,82 +319,246 @@ GVN::detectEquivalences() {
                         abort();
                 }
             }
-            auto part = pin_[bb];
-            // iterate through all instructions in the block
-            for (auto &instr : bb->get_instructions()) {
-                // ??
-                if (not instr.is_phi())
-                    part = transferFunction(&instr, instr.get_operand(1), part);
-            }
-            // and the phi instruction in all the successors
-            for (auto succ : bb->get_succ_basic_blocks()) {
-                for (auto &instr : succ->get_instructions())
-                    if (instr.is_phi()) {
-                        Instruction *pretend;
-                        // ??
-                        part = transferFunction(
-                            pretend, instr.get_operand(1), part);
-                    }
-            }
+            auto part = transferFunction(bb);
 
             // check changes in pout
             changed |= not(part == pout_[bb]);
             pout_[bb] = part;
+            _TOP[bb] = false;
         }
     } while (changed);
 }
 
 shared_ptr<Expression>
-GVN::valueExpr(Instruction *instr) {
+GVN::valueExpr(Instruction *instr, partitions *part) {
     // TODO
-    return {};
+    // ?? should use part?
+    std::string err{"Undefined"};
+    std::cout << instr->print() << std::endl;
+
+    if (instr->isBinary() or instr->is_cmp() or instr->is_fcmp()) {
+        auto op1 = instr->get_operand(0);
+        auto op2 = instr->get_operand(1);
+        auto op1_const = dynamic_cast<Constant *>(op1);
+        auto op2_const = dynamic_cast<Constant *>(op2);
+        if (op1_const and op2_const) {
+            // both are constant number, so:
+            // constant fold!
+            return ConstantExpression::create(
+                folder_->compute(instr, op1_const, op2_const));
+        } else {
+            // both none constant
+            auto op1_instr = dynamic_cast<Instruction *>(op1);
+            auto op2_instr = dynamic_cast<Instruction *>(op2);
+            assert((op1_instr or op1_const) and (op2_instr or op2_const) &&
+                   "must be this case");
+            return BinaryExpression::create(
+                instr->get_instr_type(),
+                (op1_const ? ConstantExpression::create(op1_const)
+                           : valueExpr(op1_instr)),
+                (op2_const ? ConstantExpression::create(op2_const)
+                           : valueExpr(op2_instr)));
+        }
+    } else if (instr->is_phi()) {
+        err = "phi";
+    } else if (instr->is_fp2si() or instr->is_si2fp() or instr->is_zext()) {
+        auto op = instr->get_operand(0);
+        auto op_const = dynamic_cast<Constant *>(op);
+        auto op_instr = dynamic_cast<Instruction *>(op);
+        assert(op_instr or op_const);
+
+        // get dest type
+        auto instr_fp2si = dynamic_cast<FpToSiInst *>(instr);
+        auto instr_si2fp = dynamic_cast<SiToFpInst *>(instr);
+        auto instr_zext = dynamic_cast<ZextInst *>(instr);
+        Type *dest_type = nullptr;
+        if (instr_fp2si)
+            dest_type = instr_fp2si->get_dest_type();
+        else if (instr_si2fp)
+            dest_type = instr_si2fp->get_dest_type();
+        else if (instr_zext)
+            dest_type = instr_zext->get_dest_type();
+        else
+            err = "cast";
+
+        if (dest_type) {
+            if (op_const)
+                return ConstantExpression::create(
+                    folder_->compute(instr, op_const));
+            else
+                return CastExpression::create(
+                    instr->get_instr_type(), valueExpr(op_instr), dest_type);
+        }
+    } else if (instr->is_gep()) {
+        auto operands = instr->get_operands();
+        auto ptr = operands[0];
+        std::vector<std::shared_ptr<Expression>> idxs;
+        // check for base address
+        assert(not dynamic_cast<Constant *>(ptr) and
+               dynamic_cast<Instruction *>(ptr) &&
+               "base address should only be from instruction");
+        // set idxes
+        for (int i = 1; i < operands.size(); i++) {
+            if (dynamic_cast<Constant *>(operands[i]))
+                idxs.push_back(ConstantExpression::create(
+                    dynamic_cast<Constant *>(operands[i])));
+            else {
+                assert(dynamic_cast<Instruction *>(operands[i]));
+                idxs.push_back(
+                    valueExpr(dynamic_cast<Instruction *>(operands[i])));
+            }
+        }
+        return GEPExpression::create(
+            valueExpr(dynamic_cast<Instruction *>(ptr)), idxs);
+    } else if (instr->is_load() or instr->is_alloca() or instr->is_call()) {
+        return UniqueExpression::create(instr);
+    }
+
+    std::cerr << "Undefined case: " << err << std::endl;
+    abort();
 }
 
 // instruction of the form `x = e`, mostly x is just e (SSA),
 // but for copy stmt x is a phi instruction in the successor.
 // Phi values (not copy stmt) should be handled in detectEquiv
+//
+// assert the x is an instruction that can generate a new value
+//
 /// \param bb basic block in which the transfer function is called
 GVN::partitions
 GVN::transferFunction(Instruction *x, Value *e, partitions pin) {
-    partitions pout = clone(pin);
+    partitions pout = pin;
+    // TODO: deal with copy-stmt case
+    // ?? deal with copy statement
+    auto e_instr = dynamic_cast<Instruction *>(e);
+    auto e_const = dynamic_cast<Constant *>(e);
+    assert((not e or e_instr or e_const) &&
+           "A value must be from an instruction or constant");
+    // erase the old record for x
+    std::set<Value *>::iterator it;
+    for (auto c : pin)
+        if ((it = std::find(c->members_.begin(), c->members_.end(), x)) !=
+            c->members_.end()) {
+            c->members_.erase(it);
+        }
+
     // TODO: get different ValueExpr by Instruction::OpID, modify pout
-    std::set<Value *>::iterator iter;
+    // ??
+    // get ve and vpf
+    shared_ptr<Expression> ve;
+    if (e) {
+        if (e_const)
+            ve = ConstantExpression::create(e_const);
+        else
+            ve = valueExpr(e_instr, &pin);
+    } else
+        ve = valueExpr(x, &pin);
+    auto vpf = valuePhiFunc(ve, curr_bb);
+
     for (auto c : pout) {
-        if ((iter = std::find(c->members_.begin(), c->members_.end(), x)) !=
-            c->members_.end()) {
-            // static_cast<Value *>(x))) != c->members_.end()) {
-            c->members_.erase(iter);
+        if (ve == c->value_expr_ or (vpf and vpf == c->value_phi_)) {
+            c->value_expr_ = ve;
+            c->members_.insert(x);
+        } else {
+            auto c = createCongruenceClass(new_number());
+            c->members_.insert(x);
+            c->value_expr_ = ve;
+            c->value_phi_ = vpf;
+            pout.insert(c);
         }
     }
-    auto ve = valueExpr(x);
-    auto vpf = valuePhiFunc(ve, pin);
 
-    /* pout.insert({});
-     * auto c = CongruenceClass(new_number());
-     * c.leader_ = e; */
+    /* // first version: ignore ve and vpf
+     * // and only update index, leader and members
+     * auto c = createCongruenceClass(new_number());
+     * c->leader_ = x;
+     * c->members_.insert(x);
+     * pout.insert(c); */
 
     return pout;
 }
 
+/*
+ * read the pin for the block and then execute transferFunction() for all
+ * instructions inside.
+ */
 GVN::partitions
 GVN::transferFunction(BasicBlock *bb) {
-    partitions pout = clone(pin_[bb]);
-    // ??
-    return pout;
+    curr_bb = bb;
+    int res;
+    auto part = pin_[bb];
+    /* LOG_INFO << "transferFunction(bb=" << bb->get_name() << ")\n";
+     * LOG_INFO << "pin:\n";
+     * utils::print_partitions(pin_[bb]);
+     * LOG_INFO << "pout before:\n";
+     * utils::print_partitions(pout_[bb]); */
+
+    // iterate through all instructions in the block
+    for (auto &instr : bb->get_instructions()) {
+        // ?? what about orther instructions? Are they all ok?
+        if (not instr.is_phi() and not instr.is_void())
+            part = transferFunction(&instr, nullptr, part);
+    }
+    // and the phi instruction in all the successors
+    for (auto succ : bb->get_succ_basic_blocks()) {
+        for (auto &instr : succ->get_instructions()) {
+            if (instr.is_phi()) {
+                if ((res = pretend_copy_stmt(&instr, bb) == -1))
+                    continue;
+                part = transferFunction(&instr, instr.get_operand(res), part);
+            }
+        }
+    }
+    /* LOG_INFO << "pout after:\n";
+     * utils::print_partitions(part);
+     * std::cout << std::endl; */
+    return part;
 }
 
 shared_ptr<PhiExpression>
-GVN::valuePhiFunc(shared_ptr<Expression> ve, const partitions &P) {
+GVN::valuePhiFunc(shared_ptr<Expression> ve, BasicBlock *bb) {
     // TODO
-    return {};
+    if (ve->get_expr_type() != Expression::e_bin)
+        return nullptr;
+    auto ve_bin = static_cast<BinaryExpression *>(ve.get());
+    if (ve_bin->lhs_->get_expr_type() != Expression::e_phi or
+        ve_bin->rhs_->get_expr_type() != Expression::e_phi)
+        return nullptr;
+
+    // get 2 phi expressions
+    auto lhs = static_cast<PhiExpression *>(ve_bin->lhs_.get());
+    auto rhs = static_cast<PhiExpression *>(ve_bin->rhs_.get());
+    // get 2 predecessors
+    auto pre_bbs_ = bb->get_pre_basic_blocks();
+    auto pre_1 = *pre_bbs_.begin();
+    auto pre_2 = *(++pre_bbs_.begin());
+
+    // try to get the merged value expression
+    auto vl_merge = BinaryExpression::create(ve_bin->op_, lhs->lhs_, rhs->lhs_);
+    auto vr_merge = BinaryExpression::create(ve_bin->op_, lhs->rhs_, rhs->rhs_);
+    auto vi = getVN(pout_[pre_1], vl_merge);
+    auto vj = getVN(pout_[pre_2], vr_merge);
+    if (vi == nullptr)
+        vi = valuePhiFunc(vl_merge, pre_1);
+    if (vj == nullptr)
+        vj = valuePhiFunc(vr_merge, pre_2);
+
+    if (vi and vj)
+        return PhiExpression::create(vi, vj);
+    else
+        return nullptr;
 }
 
 shared_ptr<Expression>
 GVN::getVN(const partitions &pout, shared_ptr<Expression> ve) {
     // TODO: return what?
+    /* for (auto c : pout) {
+     *     if (c->value_expr_ == ve)
+     *         return ve;
+     * } */
     for (auto it = pout.begin(); it != pout.end(); it++)
         if ((*it)->value_expr_ and *(*it)->value_expr_ == *ve)
-            return {};
+            return ve;
     return nullptr;
 }
 
@@ -490,6 +676,12 @@ GVNExpression::operator==(const Expression &lhs, const Expression &rhs) {
             return equiv_as<BinaryExpression>(lhs, rhs);
         case Expression::e_phi:
             return equiv_as<PhiExpression>(lhs, rhs);
+        case Expression::e_cast:
+            return equiv_as<CastExpression>(lhs, rhs);
+        case Expression::e_gep:
+            return equiv_as<GEPExpression>(lhs, rhs);
+        case Expression::e_unique:
+            return equiv_as<UniqueExpression>(lhs, rhs);
     }
 }
 
@@ -517,12 +709,35 @@ operator==(const GVN::partitions &p1, const GVN::partitions &p2) {
     // cannot direct compare???
     if (p1.size() != p2.size())
         return false;
-    return std::equal(p1.begin(), p1.end(), p2.begin(), p2.end());
+    auto it1 = p1.begin();
+    auto it2 = p2.begin();
+    for (; it1 != p1.end(); ++it1, ++it2)
+        if (not(**it1 == **it2))
+            return false;
+    return true;
 }
 
-// only compare index
+// only compare members
 bool
 CongruenceClass::operator==(const CongruenceClass &other) const {
     // TODO: which fields need to be compared?
-    return index_ == other.index_;
+    if (members_.size() != other.members_.size())
+        return false;
+    return members_ == other.members_;
+}
+
+int
+GVN::pretend_copy_stmt(Instruction *instr, BasicBlock *bb) {
+    auto phi = static_cast<PhiInst *>(instr);
+    // res = phi [op1, name1], [op2, name2]
+    //            ^0   ^1       ^2   ^3
+    if (phi->get_operand(1)->get_name() == bb->get_name()) {
+        // pretend copy statement:
+        // `res = op1`
+        return 0;
+    } else if (phi->get_operand(3)->get_name() == bb->get_name()) {
+        // `res = op2`
+        return 2;
+    }
+    return -1;
 }
diff --git a/tests/4-ir-opt/testcases/GVN/functional/.gitignore b/tests/4-ir-opt/testcases/GVN/functional/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..fd645655007deecf92e33c8371dd762c0251d69a
--- /dev/null
+++ b/tests/4-ir-opt/testcases/GVN/functional/.gitignore
@@ -0,0 +1 @@
+*.ll