diff --git a/include/llir_type.h b/include/llir_type.h
index faebbdc..38309d7 100644
--- a/include/llir_type.h
+++ b/include/llir_type.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "common.h"
 #include <memory>
 #include <vector>
 namespace antlrSysY {
@@ -69,6 +70,14 @@ public:
   ArrayType() : Type(TypeTag::ArrayType) {}
   ArrayType(TypePtr_t element_type, int element_count)
       : Type(TypeTag::ArrayType), element_count(element_count), element_type(element_type) {}
+  static std::shared_ptr<ArrayType> build_from_list(const std::vector<int> &dim_list) {
+    TypePtr_t array_type = TypeHelper::TYPE_I32;
+    sysy_assert(dim_list.size() != 0);
+    for (auto itr = dim_list.rbegin(); itr != dim_list.rend(); ++itr) {
+      array_type = std::make_shared<ArrayType>(array_type, *itr);
+    }
+    return std::dynamic_pointer_cast<ArrayType>(array_type);
+  }
 };
 
 class PointerType : public Type {
diff --git a/include/llir_value.h b/include/llir_value.h
index c9c240b..c4a2b7a 100644
--- a/include/llir_value.h
+++ b/include/llir_value.h
@@ -5,6 +5,7 @@
 #include <string>
 #include <vector>
 
+#include "common.h"
 #include "llir_type.h"
 
 namespace antlrSysY {
@@ -50,18 +51,46 @@ public:
   }
 };
 
-class ConstantInt : public Value {
+typedef std::shared_ptr<Value> ValuePtr_t;
+typedef std::shared_ptr<BasicBlock> BasicBlockPtr_t;
+typedef std::shared_ptr<Function> FunctionPtr_t;
+
+class Constant : public Value {
 public:
-  int value;
-  ConstantInt(const std::string &name, int value) : Value(name, TypeHelper::TYPE_I32), value(value) {}
+  Constant(const std::string &name, TypePtr_t type) : Value(name, type) {}
 };
 
-class ConstantArr : public Value {};
-
-class GlobalVarInt : public Value {
+class ConstantInt : public Constant {
 public:
-  int init_value;
-  GlobalVarInt(const std::string &name, int init_value) : Value(name, TypeHelper::TYPE_I32), init_value(init_value) {}
+  int value;
+  ConstantInt(const std::string &name, int value) : Constant(name, TypeHelper::TYPE_I32), value(value) {}
+  static std::shared_ptr<ConstantInt> make_shared(int value) {
+    return std::make_shared<ConstantInt>("", value);
+  }
+};
+
+class ConstantArr : public Constant {
+public:
+  std::vector<ValuePtr_t> value_list;
+  ConstantArr(const std::string &name, const std::vector<ValuePtr_t> &value_list, std::shared_ptr<ArrayType> type)
+      : Constant(name, type), value_list(value_list) {}
+  static std::shared_ptr<ConstantArr> make_shared(const std::string &name, const std::vector<ValuePtr_t> &value_list,
+                                                  std::shared_ptr<ArrayType> type) {
+    return std::make_shared<ConstantArr>(name, value_list, type);
+  }
+};
+
+typedef std::shared_ptr<Constant> ConstantPtr_t;
+
+class GlobalVar : public Value {
+public:
+  ConstantPtr_t init_value;
+  bool is_const;
+  GlobalVar(const std::string &name, ConstantPtr_t init_value, bool is_const)
+      : Value(name, init_value->type), init_value(init_value), is_const(is_const) {}
+  static std::shared_ptr<GlobalVar> make_shared(const std::string &name, ConstantPtr_t init_value, bool is_const) {
+    return std::make_shared<GlobalVar>(name, init_value, is_const);
+  }
 };
 
 enum class InstTag {
@@ -93,9 +122,6 @@ enum class InstTag {
   ExtractEle
 };
 
-typedef std::shared_ptr<Value> ValuePtr_t;
-typedef std::shared_ptr<BasicBlock> BasicBlockPtr_t;
-typedef std::shared_ptr<Function> FunctionPtr_t;
 class Instruction : public Value {
 public:
   InstTag tag;
@@ -107,9 +133,8 @@ public:
 
 class InstAlloca : public Instruction {
 public:
-  bool isInit = false;
-  InstAlloca(TypePtr_t alloc_type, bool isInit, std::shared_ptr<BasicBlock> parent_bb)
-      : Instruction(InstTag::Alloca, std::make_shared<PointerType>(alloc_type), parent_bb), isInit(isInit) {}
+  InstAlloca(TypePtr_t alloc_type, std::shared_ptr<BasicBlock> parent_bb)
+      : Instruction(InstTag::Alloca, std::make_shared<PointerType>(alloc_type), parent_bb) {}
 };
 
 class InstStore : public Instruction {
@@ -177,8 +202,46 @@ public:
   InstCall(FunctionPtr_t func, const std::vector<ValuePtr_t> &args, BasicBlockPtr_t parent_bb)
       : Instruction(InstTag::Call, func->get_type()->return_type, parent_bb) {
     operand_list.push_back(func);
-    for (auto arg : args) {
-      operand_list.push_back(arg);
+    operand_list.insert(operand_list.end(), args.begin(), args.end());
+  }
+};
+
+// getelementptr <ty>, ptr <ptrval>{, [inrange] <ty> <idx>}*
+// Example: lea arr[2][3] from arr[5][4]:
+//  &arr[2][3] = GEP [5x[4xi32]], [5x[4xi32]]* arr, i32 0, i32 2, i32 3
+class InstGEP : public Instruction {
+public:
+  ValuePtr_t aim_to;
+  TypePtr_t element_type;
+  InstGEP(ValuePtr_t pointer, const std::vector<ValuePtr_t> &indices, BasicBlockPtr_t parent_bb)
+      : Instruction(InstTag::GEP, std::make_shared<PointerType>(extract_type(pointer, indices)), parent_bb) {
+    if (typeid(pointer) == typeid(std::shared_ptr<InstGEP>)) {
+      aim_to = std::dynamic_pointer_cast<InstGEP>(pointer)->aim_to;
+    }
+    else {
+      sysy_assert(typeid(pointer) == typeid(std::shared_ptr<InstAlloca>) ||
+                  typeid(pointer) == typeid(std::shared_ptr<GlobalVar>));
+      aim_to = pointer;
+    }
+    element_type = extract_type(pointer, indices);
+    operand_list.push_back(pointer);
+    operand_list.insert(operand_list.end(), indices.begin(), indices.end());
+  }
+
+  // get the inner
+  static TypePtr_t extract_type(ValuePtr_t pointer, const std::vector<ValuePtr_t> &indices) {
+    auto pointer_type = std::dynamic_pointer_cast<PointerType>(pointer->type);
+    auto pointed_type = pointer_type->pointed_type;
+    if (pointed_type->type_tag == Type::TypeTag::ArrayType) {
+      for (int i = 1; i < indices.size() - 1; ++i) {
+        pointed_type = std::dynamic_pointer_cast<ArrayType>(pointed_type)->element_type;
+      }
+    }
+    if (pointed_type->type_tag == Type::TypeTag::IntegerType) {
+      return pointed_type;
+    }
+    else {
+      panic("Unmatch indices and array pointer");
     }
   }
 };
diff --git a/include/visitor.h b/include/visitor.h
index 62313f0..b0b08c3 100644
--- a/include/visitor.h
+++ b/include/visitor.h
@@ -29,7 +29,7 @@ std::shared_ptr<InstLoad> build_InstLoad(std::shared_ptr<Value> value, TypePtr_t
 std::shared_ptr<InstStore> build_InstStore(std::shared_ptr<Value> value, std::shared_ptr<Value> pointer,
                                            std::shared_ptr<BasicBlock> parent_bb);
 
-std::shared_ptr<InstAlloca> build_InstAlloca(TypePtr_t type, bool isInit, std::shared_ptr<BasicBlock> parent_bb);
+std::shared_ptr<InstAlloca> build_InstAlloca(TypePtr_t type, std::shared_ptr<BasicBlock> parent_bb);
 
 std::shared_ptr<InstBinary> build_InstBinary(InstTag inst_tag, std::shared_ptr<Value> op1, std::shared_ptr<Value> op2,
                                              std::shared_ptr<BasicBlock> parent_bb);
@@ -47,18 +47,22 @@ std::shared_ptr<InstReturn> build_InstReturn(BasicBlockPtr_t parent_bb);
 
 std::shared_ptr<InstCall> build_InstCall(FunctionPtr_t func, const std::vector<ValuePtr_t> &args,
                                          BasicBlockPtr_t parent_bb);
+std::shared_ptr<InstGEP> build_InstGEP(ValuePtr_t pointer, const std::vector<ValuePtr_t> &indices,
+                                       BasicBlockPtr_t parent_bb);
+
 #pragma endregion
 
 class Visitor : public antlrSysY::SysyBaseVisitor {
 private:
   struct VisitorState {
-    bool isGlobalInt = false;
+    bool isGlobalIint = false;
     bool isConstInt = false;
     bool isRealParam = false;
     bool isCondExp = false;
     std::shared_ptr<Function> current_func = {};
     std::shared_ptr<BasicBlock> current_bb = {};
-
+    std::vector<int> *arr_dim_list = nullptr;
+    int arr_dim_index = 0;
     struct loop_record {
       BasicBlockPtr_t cond, body, next;
       int id;
diff --git a/scripts/compiler.py b/scripts/compiler.py
index 8fa21dd..089a626 100644
--- a/scripts/compiler.py
+++ b/scripts/compiler.py
@@ -18,6 +18,8 @@ class Compiler:
         self.obj_template = f"build/test_results/{{testcase}}/obj/{scheme}.o"
         self.bin_template = f"build/test_results/{{testcase}}/bin/{scheme}"
         self.compile_log = f"build/log/compile_log/{{testcase}}/{scheme}.log"
+        
+        self.count_error = 0
 
         for testcase in testcases:
             self.__generate_path(testcase)
@@ -64,6 +66,7 @@ class Compiler:
         completed = subprocess.run(frontend_instr.format(header=header, sy=sy, ir=ir).split(), stdout=log_file, stderr=log_file, bufsize=1)
         if completed.returncode != 0:
             Print_C.print_error(f"Generating {self.scheme}.ll failed! See {log}")
+            self.count_error += 1
         log_file.close()
 
 
@@ -142,5 +145,8 @@ class Compiler:
         for testcase in self.testcases:
             Print_C.print_subheader(f"[Compiling {self.scheme} | {testcase}]")
             self.sy_to_ir(frontend_instr=frontend_instr, testcase=testcase, category=category)
+            if self.count_error >= 10:
+                Print_C.print_error(f"Test script stopped due to too many errors")
+                return
 
         
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index 9dcd838..31d095b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -59,6 +59,9 @@ int main(int argc, const char **argv) {
 #pragma endregion
 
   std::ifstream ifs_source_file(source_file);
+  if (!ifs_source_file.good()) {
+    LOG(ERROR) << "Source file " << source_file << " not found.";
+  }
   ANTLRInputStream input(ifs_source_file);
   SysyLexer lexer(&input);
   CommonTokenStream tokens(&lexer);
diff --git a/src/visit_factory.cpp b/src/visit_factory.cpp
index 1aadf62..d78da0e 100644
--- a/src/visit_factory.cpp
+++ b/src/visit_factory.cpp
@@ -31,8 +31,8 @@ std::shared_ptr<InstStore> build_InstStore(std::shared_ptr<Value> value, std::sh
   return inst_store;
 }
 
-std::shared_ptr<InstAlloca> build_InstAlloca(TypePtr_t type, bool isInit, std::shared_ptr<BasicBlock> parent_bb) {
-  auto inst_alloca = std::make_shared<InstAlloca>(type, isInit, parent_bb);
+std::shared_ptr<InstAlloca> build_InstAlloca(TypePtr_t type, std::shared_ptr<BasicBlock> parent_bb) {
+  auto inst_alloca = std::make_shared<InstAlloca>(type, parent_bb);
   parent_bb->inst_list.push_back(inst_alloca);
   return inst_alloca;
 }
@@ -91,4 +91,11 @@ std::shared_ptr<InstCall> build_InstCall(FunctionPtr_t func, const std::vector<V
   return inst;
 }
 
+std::shared_ptr<InstGEP> build_InstGEP(ValuePtr_t pointer, const std::vector<ValuePtr_t> &indices,
+                                       BasicBlockPtr_t parent_bb) {
+  auto inst = std::make_shared<InstGEP>(pointer, indices, parent_bb);
+  parent_bb->inst_list.push_back(inst);
+  return inst;
+}
+
 } // namespace antlrSysY
\ No newline at end of file
diff --git a/src/visitor.cpp b/src/visitor.cpp
index f16cdad..a92d7d1 100644
--- a/src/visitor.cpp
+++ b/src/visitor.cpp
@@ -1,4 +1,5 @@
 #include "visitor.h"
+#include "3rdparty/easylogging++.h"
 #include "common.h"
 #include "llir_type.h"
 #include "llir_value.h"
@@ -19,7 +20,7 @@ namespace antlrSysY {
     return value;                                                                                                      \
   }
 
-ValuePtr_t any_to_Value(const std::any &fuck_any) {
+static ValuePtr_t any_to_Value(const std::any &fuck_any) {
   ANY2VALUE(Value)
   ANY2VALUE(User)
   ANY2VALUE(FParam)
@@ -27,7 +28,8 @@ ValuePtr_t any_to_Value(const std::any &fuck_any) {
   ANY2VALUE(BasicBlock)
   ANY2VALUE(ConstantInt)
   ANY2VALUE(ConstantArr)
-  ANY2VALUE(GlobalVarInt)
+  ANY2VALUE(Constant)
+  ANY2VALUE(GlobalVar)
   ANY2VALUE(Instruction)
   ANY2VALUE(InstAlloca)
   ANY2VALUE(InstStore)
@@ -48,101 +50,273 @@ std::any Visitor::visitConstDecl(SysyParser::ConstDeclContext *ctx) {
   return {};
 }
 
+// constInitVal is compulsory
 // constDef : IDENT ('[' constExp ']')* '=' constInitVal ';'
 std::any Visitor::visitConstDef(SysyParser::ConstDefContext *ctx) {
-  auto name = ctx->IDENT()->getText();
-  LOG(DEBUG) << "Visiting ConstDef " << name;
-  if (_scope_tab.get_name(name, _scope_tab.get_level()).has_value())
+  const auto const_name = ctx->IDENT()->getText();
+  LOG(DEBUG) << "Visiting ConstDef " << const_name;
+  if (_scope_tab.get_name(const_name, _scope_tab.get_level()).has_value())
     throw GrammarException("Duplicate const def");
 
   // not array
   if (ctx->constExp().empty()) {
-    if (ctx->constInitVal() != nullptr) {
-      auto result = std::any_cast<int>(visit(ctx->constInitVal()));
-      auto constint = build_ConstantInt(name, result);
-      _scope_tab.push_name(name, constint);
+    auto result = std::any_cast<std::shared_ptr<ConstantInt>>(visitConstInitVal(ctx->constInitVal()));
+    _scope_tab.push_name(const_name, result);
+  }
+  // const array
+  else {
+    std::vector<int> dim_list;
+    auto const_exp_list = ctx->constExp();
+    // collect size of each dimension
+    for (auto const_exp : const_exp_list) {
+      auto n_elem = std::any_cast<std::shared_ptr<ConstantInt>>(visitConstExp(const_exp));
+      dim_list.push_back(n_elem->value);
+    }
+    auto array_type = ArrayType::build_from_list(dim_list);
+    // anyways, first collect init value
+    _state.arr_dim_index = 0;
+    _state.arr_dim_list = &dim_list;
+    auto array_value = std::any_cast<std::vector<ValuePtr_t>>(visitConstInitVal(ctx->constInitVal()));
+    _state.arr_dim_list = nullptr;
+    sysy_assert(_state.arr_dim_index == 0);
+
+    if (_scope_tab.get_level()) {
+      // local const array
+      // Keep a pointer to the base address, alloca_ = &array, *alloca_ = &array[0]
+      auto alloca_ = build_InstAlloca(array_type, _state.current_bb);
+      _scope_tab.push_name(const_name, alloca_);
+      // first dim base, ptr = *alloca_ = &array[0]
+      auto base_ptr = build_InstGEP(alloca_, {CONST0, CONST0}, _state.current_bb);
+      // get the first element's base, final ptr = &a[0][0]...[0]
+      for (int i = 1; i < dim_list.size(); ++i) {
+        base_ptr = build_InstGEP(base_ptr, {CONST0, CONST0}, _state.current_bb);
+      }
+      // we store the elements in 1-dim shape
+      build_InstStore(array_value[0], base_ptr, _state.current_bb);
+      for (int i = 1; i < array_value.size(); ++i) {
+        auto ptr = build_InstGEP(base_ptr, {ConstantInt::make_shared(i)}, _state.current_bb);
+        build_InstStore(array_value[i], ptr, _state.current_bb);
+      }
+    }
+    else {
+      // global const array
+      auto const_arr = ConstantArr::make_shared("const_arr", array_value, array_type);
+      auto global_var = GlobalVar::make_shared(const_name, const_arr, true);
+      _scope_tab.push_name(const_name, global_var);
     }
   }
   return {};
 }
 
+// initVal is optional
+// varDef: IDENT ('[' constExp ']')* ('=' initVal)?;
 std::any Visitor::visitVarDef(SysyParser::VarDefContext *ctx) {
-  auto name = ctx->IDENT()->getText();
-  LOG(DEBUG) << "Visiting VarDef " << name;
-  if (_scope_tab.get_name(name, _scope_tab.get_level()).has_value())
+  auto var_name = ctx->IDENT()->getText();
+  LOG(DEBUG) << "Visiting VarDef " << var_name;
+  if (_scope_tab.get_name(var_name, _scope_tab.get_level()).has_value())
     panic("Duplicate const def");
   // Not Array
   if (ctx->constExp().empty()) {
     // global variable
     if (_scope_tab.get_level() == 0) {
       // global variable must be initialized, either specified or zeroed
-      int result = 0;
       if (ctx->initVal()) {
-        _state.isGlobalInt = true;
-        result = std::any_cast<int>(visit(ctx->initVal()));
-        _state.isGlobalInt = false;
+        _state.isGlobalIint = true;
+        auto result = std::any_cast<std::shared_ptr<ConstantInt>>(visitInitVal(ctx->initVal()));
+        _state.isGlobalIint = false;
+        auto global_var_int = std::make_shared<GlobalVar>(var_name, result, false);
+        _scope_tab.push_name(var_name, global_var_int);
+      }
+      else {
+        auto global_var_int = std::make_shared<GlobalVar>(var_name, CONST0, false);
+        _scope_tab.push_name(var_name, global_var_int);
       }
-      auto global_var_int = std::make_shared<GlobalVarInt>(name, result);
-      _scope_tab.push_name(name, global_var_int);
     }
     // local variable
     else {
-      auto alloca = build_InstAlloca(TypeHelper::TYPE_I32, false, _state.current_bb);
-      _scope_tab.push_name(name, alloca);
+      auto alloca_ = build_InstAlloca(TypeHelper::TYPE_I32, _state.current_bb);
+      _scope_tab.push_name(var_name, alloca_);
       if (ctx->initVal()) {
         auto init_val = any_to_Value(visitInitVal(ctx->initVal()));
-        build_InstStore(init_val, alloca, _state.current_bb);
+        build_InstStore(init_val, alloca_, _state.current_bb);
       }
     }
   }
   else {
-    // Array
-    panic("To be implemented");
+    std::vector<int> dim_list;
+    auto const_exp_list = ctx->constExp();
+    // collect size of each dimension
+    for (auto const_exp : const_exp_list) {
+      auto n_elem = std::any_cast<std::shared_ptr<ConstantInt>>(visitConstExp(const_exp));
+      dim_list.push_back(n_elem->value);
+    }
+    auto array_type = ArrayType::build_from_list(dim_list);
+    // local array
+    if (_scope_tab.get_level()) {
+      auto alloca_ = build_InstAlloca(array_type, _state.current_bb);
+      _scope_tab.push_name(var_name, alloca_);
+      if (ctx->initVal()) {
+        _state.arr_dim_index = 0;
+        _state.arr_dim_list = &dim_list;
+        auto array_value = std::any_cast<std::vector<ValuePtr_t>>(visitInitVal(ctx->initVal()));
+        _state.arr_dim_list = nullptr;
+        sysy_assert(_state.arr_dim_index == 0);
+        // Build GEP
+        auto base_ptr = build_InstGEP(alloca_, {CONST0, CONST0}, _state.current_bb);
+        for (int i = 1; i < dim_list.size(); ++i) {
+          base_ptr = build_InstGEP(base_ptr, {CONST0, CONST0}, _state.current_bb);
+        }
+        // TODO: BAAU-2021 calls memset in `libc` (not sysylib) to optimize this process
+        build_InstStore(array_value[0], base_ptr, _state.current_bb);
+        for (int i = 1; i < array_value.size(); ++i) {
+          auto ptr = build_InstGEP(base_ptr, {ConstantInt::make_shared(i)}, _state.current_bb);
+          build_InstStore(array_value[i], ptr, _state.current_bb);
+        }
+      }
+      // If there is no init expr, let it be
+    }
+    // global array, generally the same as constant global array
+    else {
+      if (ctx->initVal()) {
+        // first collect init value
+        _state.isGlobalIint = true;
+        _state.arr_dim_index = 0;
+        _state.arr_dim_list = &dim_list;
+        auto array_value = std::any_cast<std::vector<ValuePtr_t>>(visitInitVal(ctx->initVal()));
+        _state.arr_dim_list = nullptr;
+        sysy_assert(_state.arr_dim_index == 0);
+        _state.isGlobalIint = false;
+        auto const_arr = ConstantArr::make_shared("var_arr", array_value, array_type);
+        auto global_var = GlobalVar::make_shared(var_name, const_arr, false);
+        _scope_tab.push_name(var_name, global_var);
+      }
+      else {
+        auto global_var = GlobalVar::make_shared(var_name, CONST0, false);
+        _scope_tab.push_name(var_name, global_var);
+      }
+    }
   }
   return {};
 }
 
 std::any Visitor::visitInitVal(SysyParser::InitValContext *ctx) {
   if (ctx->exp()) {
-    if (_state.isGlobalInt)
+    if (_state.isGlobalIint)
       _state.isConstInt = true;
-    auto retval = visit(ctx->exp());
-    if (_state.isGlobalInt)
+    auto retval = visitExp(ctx->exp());
+    if (_state.isGlobalIint)
       _state.isConstInt = false;
     return retval;
   }
   // Array
-  panic("To be implemented");
-}
-
-std::any Visitor::visitConstInitVal(SysyParser::ConstInitValContext *ctx) {
-  if (ctx->constExp() != nullptr /*&& ctx->arrDim.size() == 0*/) {
-    return visit(ctx->constExp());
+  else {
+    sysy_assert(_state.arr_dim_list);
+    int cur_dim = _state.arr_dim_list->at(_state.arr_dim_index);
+    int elem_size = 1;
+    std::vector<ValuePtr_t> cur_arr;
+    for (int i = _state.arr_dim_index + 1; i < _state.arr_dim_list->size(); ++i) {
+      elem_size *= _state.arr_dim_list->at(i);
+    }
+    for (auto init_val : ctx->initVal()) {
+      if (init_val->exp()) {
+        if (_state.isGlobalIint) {
+          auto const_value = any_to_Value(visitInitVal(init_val));
+          // should evaluate to const int
+          sysy_assert(typeid(const_value) == typeid(std::shared_ptr<ConstantInt>));
+          cur_arr.push_back(const_value);
+        }
+        else {
+          // God knows what it evaluates to
+          auto exp_value = any_to_Value(visitInitVal(init_val));
+          cur_arr.push_back(exp_value);
+        }
+      }
+      else {
+        // evaluate sub-array
+        // before evaluate the new sub-array, first fill up the last one
+        const int pos = cur_arr.size();
+        // the additional `%elem_size`: what if the last dim is {}?
+        for (int i = 0; i < (elem_size - (pos % elem_size)) % elem_size; ++i) {
+          cur_arr.push_back(CONST0);
+        }
+        _state.arr_dim_index++;
+        auto sub_array = std::any_cast<std::vector<ValuePtr_t>>(visitInitVal(init_val));
+        _state.arr_dim_index--;
+        cur_arr.insert(cur_arr.end(), sub_array.begin(), sub_array.end());
+      }
+    }
+    // fill up the rest
+    for (int i = cur_arr.size(); i < cur_dim * elem_size; ++i) {
+      cur_arr.push_back(CONST0);
+    }
+    return cur_arr;
   }
-  panic("To be implemented");
 }
 
+// TODO: Replace all any<int> to ConstantInt
+// constInitVal: constExp | ('{' (constInitVal (',' constInitVal)*)? '}');
+std::any Visitor::visitConstInitVal(SysyParser::ConstInitValContext *ctx) {
+  if (ctx->constExp() != nullptr) {
+    return visitConstExp(ctx->constExp());
+  }
+  else {
+    sysy_assert(_state.arr_dim_list);
+    int cur_dim = _state.arr_dim_list->at(_state.arr_dim_index);
+    int elem_size = 1;
+    std::vector<ValuePtr_t> cur_arr;
+    for (int i = _state.arr_dim_index + 1; i < _state.arr_dim_list->size(); ++i) {
+      elem_size *= _state.arr_dim_list->at(i);
+    }
+    for (auto init_val : ctx->constInitVal()) {
+      if (init_val->constExp()) {
+        // evaluate to const int
+        auto const_value = any_to_Value(visitConstInitVal(init_val));
+        sysy_assert(TypeHelper::isIntegerType(const_value->type));
+        cur_arr.push_back(const_value);
+      }
+      else {
+        // evaluate to sub-array
+        // before evaluate the new sub-array, first fill up the last one
+        int pos = cur_arr.size();
+        // the additional `%elem_size`: what if the last dim is {}?
+        for (int i = 0; i < (elem_size - (pos % elem_size)) % elem_size; ++i) {
+          cur_arr.push_back(CONST0);
+        }
+        _state.arr_dim_index++;
+        auto sub_array = std::any_cast<std::vector<ValuePtr_t>>(visitConstInitVal(init_val));
+        _state.arr_dim_index--;
+        cur_arr.insert(cur_arr.end(), sub_array.begin(), sub_array.end());
+      }
+    }
+    // fill up the rest
+    for (int i = cur_arr.size(); i < cur_dim * elem_size; ++i) {
+      cur_arr.push_back(CONST0);
+    }
+    return cur_arr;
+  }
+}
+
+// @retval: int
 std::any Visitor::visitConstExp(SysyParser::ConstExpContext *ctx) {
   if (ctx->addExp() == nullptr)
     panic("Unreachable");
   _state.isConstInt = true;
-  int result = std::any_cast<int>(visit(ctx->addExp()));
+  auto result = std::any_cast<std::shared_ptr<ConstantInt>>(visitAddExp(ctx->addExp()));
   _state.isConstInt = false;
-  LOG(DEBUG) << "ConstExp Eval to " << result;
+  LOG(DEBUG) << "ConstExp Eval to " << result->value;
   return {result};
 }
 
 // addExp: mulExp | addExp ('+' | '-') mulExp;
 std::any Visitor::visitAddExp(SysyParser::AddExpContext *ctx) {
   if (_state.isConstInt) {
-    int result = std::any_cast<int>(visit(ctx->mulExp()));
-    int add_result = 0;
+    auto result = std::any_cast<std::shared_ptr<ConstantInt>>(visitMulExp(ctx->mulExp()));
     if (ctx->addExp()) {
-      add_result = std::any_cast<int>(visit(ctx->addExp()));
+      auto add_result = std::any_cast<std::shared_ptr<ConstantInt>>(visitAddExp(ctx->addExp()));
       if (ctx->ADD())
-        result = add_result + result;
+        result->value = add_result->value + result->value;
       else if (ctx->SUB())
-        result = add_result - result;
+        result->value = add_result->value - result->value;
       else
         panic("missing operator");
     }
@@ -173,17 +347,17 @@ std::any Visitor::visitAddExp(SysyParser::AddExpContext *ctx) {
 
 std::any Visitor::visitMulExp(SysyParser::MulExpContext *ctx) {
   if (_state.isConstInt) {
-    int result = std::any_cast<int>(visitUnaryExp(ctx->unaryExp()));
+    auto result = std::any_cast<std::shared_ptr<ConstantInt>>(visitUnaryExp(ctx->unaryExp()));
     if (ctx->mulExp()) {
-      int mul_result = std::any_cast<int>(visit(ctx->mulExp()));
+      auto mul_result = std::any_cast<std::shared_ptr<ConstantInt>>(visitMulExp(ctx->mulExp()));
       if (ctx->MUL()) {
-        result = mul_result * result;
+        result->value = mul_result->value * result->value;
       }
       else if (ctx->DIV()) {
-        result = mul_result / result;
+        result->value = mul_result->value / result->value;
       }
       else if (ctx->MOD()) {
-        result = mul_result % result;
+        result->value = mul_result->value % result->value;
       }
       else
         panic("Unreachable");
@@ -299,13 +473,13 @@ std::any Visitor::visitLOrExp(SysyParser::LOrExpContext *ctx) {
 std::any Visitor::visitUnaryExp(SysyParser::UnaryExpContext *ctx) {
   if (_state.isConstInt) {
     if (ctx->unaryExp()) {
-      int result = std::any_cast<int>(visit(ctx->unaryExp()));
+      auto result = std::any_cast<std::shared_ptr<ConstantInt>>(visitUnaryExp(ctx->unaryExp()));
       if (ctx->unaryOp()->ADD())
-        result = +result;
+        result->value = +result->value;
       else if (ctx->unaryOp()->SUB())
-        result = -result;
+        result->value = -result->value;
       else if (ctx->unaryOp()->NOT())
-        result = !result;
+        result->value = !result->value;
       else
         panic("Unreachable");
       return {result};
@@ -376,7 +550,7 @@ std::any Visitor::visitPrimaryExp(SysyParser::PrimaryExpContext *ctx) {
       return visitExp(ctx->exp());
     }
     else if (ctx->lVal()) {
-      auto value = any_to_Value(visit(ctx->lVal()));
+      auto value = any_to_Value(visitLVal(ctx->lVal()));
       auto constint = std::dynamic_pointer_cast<ConstantInt>(value);
       // actually, it is only a type assertion
       return constint->value;
@@ -418,32 +592,26 @@ std::any Visitor::visitPrimaryExp(SysyParser::PrimaryExpContext *ctx) {
     }
     panic("Unreachable");
   }
-  return {};
 }
 
-// @retval: int
+// @retval: ConstantInt
 std::any Visitor::visitNumber(SysyParser::NumberContext *ctx) {
-  auto int_const = std::any_cast<int>(visit(ctx->intConst()));
-  if (_state.isConstInt) {
-    return int_const;
-  }
-  else {
-    return std::dynamic_pointer_cast<Value>(build_ConstantInt("", int_const));
-  }
+  return visitIntConst(ctx->intConst());
 }
 
-// @retval: int
+// @retval: ConstantInt
 std::any Visitor::visitIntConst(SysyParser::IntConstContext *ctx) {
+  int const_int = 0;
   if (ctx->DECIMAL_CONST()) {
-    return std::stoi(ctx->DECIMAL_CONST()->getText(), nullptr, 10);
+    const_int = std::stoi(ctx->DECIMAL_CONST()->getText(), nullptr, 10);
   }
   else if (ctx->HEXADECIMAL_CONST()) {
-    return std::stoi(ctx->HEXADECIMAL_CONST()->getText(), nullptr, 16);
+    const_int = std::stoi(ctx->HEXADECIMAL_CONST()->getText(), nullptr, 16);
   }
   else if (ctx->OCTAL_CONST()) {
-    return std::stoi(ctx->OCTAL_CONST()->getText(), nullptr, 8);
+    const_int = std::stoi(ctx->OCTAL_CONST()->getText(), nullptr, 8);
   }
-  return {};
+  return build_ConstantInt("", const_int);
 }
 
 // lVal: IDENT ('[' exp ']')*;
@@ -460,17 +628,107 @@ std::any Visitor::visitLVal(SysyParser::LValContext *ctx) {
   }
   if (lval->type->type_tag == Type::TypeTag::PointerType) {
     auto ptr_type = std::dynamic_pointer_cast<PointerType>(lval->type);
-    if (ptr_type->pointed_type->type_tag == Type::TypeTag::IntegerType) {
-      // @retval: InstAlloca
+    switch (ptr_type->pointed_type->type_tag) {
+    case Type::TypeTag::IntegerType: {
+      // Int
       if (ctx->exp().empty()) {
+        // int ref
+        // @retval: InstAlloca
         return lval;
       }
       else {
-        panic("To be implemented");
+        LOG(WARNING) << "Unexpected array referece";
+        // array index, perhaps
+        // @retval: InstGEP
+        auto gep = lval;
+        for (auto exp_ctx : ctx->exp()) {
+          auto exp = any_to_Value(visitExp(exp_ctx));
+          gep = build_InstGEP(gep, {exp}, _state.current_bb);
+        }
+        return gep;
+      }
+    };
+    case Type::TypeTag::PointerType: {
+      if (ctx->exp().empty()) {
+        // ??? Pointer
+        // @retval: InstLoad
+        LOG(WARNING) << "Unexpected pointer";
+        auto pointed_type = std::dynamic_pointer_cast<PointerType>(lval)->pointed_type;
+        auto inst_load = build_InstLoad(lval, pointed_type, _state.current_bb);
+        return inst_load;
+      }
+      else {
+        // fparam array, whose first dim is represented by a pointer
+        auto pointed_type = std::dynamic_pointer_cast<PointerType>(lval)->pointed_type;
+        sysy_assert(pointed_type->type_tag == Type::TypeTag::ArrayType);
+        auto inst_load = build_InstLoad(lval, pointed_type, _state.current_bb);
+
+        auto ptr = build_InstGEP(inst_load, {CONST0}, _state.current_bb);
+        pointed_type = std::dynamic_pointer_cast<PointerType>(ptr->type)->pointed_type;
+        ValuePtr_t offset = ConstantInt::make_shared(0);
+        auto exp_list = ctx->exp();
+        // calculate offset by hand: offset = (offset + exp[i]) * dim_size[i]
+        for (int i = 0; i < exp_list.size() - 1; ++i) {
+          sysy_assert(typeid(pointed_type) == typeid(std::shared_ptr<ArrayType>));
+          auto array_type = std::dynamic_pointer_cast<ArrayType>(pointed_type);
+          auto exp_val = any_to_Value(visitExp(exp_list[i]));
+          auto dim_size = ConstantInt::make_shared(array_type->element_count);
+          auto inst_add = build_InstBinary(InstTag::Add, offset, exp_val, _state.current_bb);
+          auto inst_mul = build_InstBinary(InstTag::Mul, inst_add, dim_size, _state.current_bb);
+          offset = inst_mul;
+          pointed_type = array_type->element_type;
+          ptr = build_InstGEP(ptr, {CONST0, CONST0}, _state.current_bb);
+        }
+
+        // visit the last dimension, mul is not needed
+        auto exp_val = any_to_Value(visitExp(exp_list.back()));
+        auto inst_add = build_InstBinary(InstTag::Add, offset, exp_val, _state.current_bb);
+        offset = inst_add; // finally, we get the offset
+        pointed_type = std::dynamic_pointer_cast<PointerType>(ptr->type)->pointed_type;
+        if (TypeHelper::isIntegerType(pointed_type)) {
+          // return the address of the array element
+          auto arr_elem_ptr = build_InstGEP(ptr, {offset}, _state.current_bb);
+          return arr_elem_ptr;
+        }
+        else {
+          panic("Should be int");
+        }
       }
     }
-    else {
-      panic("To be implemented");
+    case Type::TypeTag::ArrayType: {
+      sysy_assert(!ctx->exp().empty());
+      // get &array[0]
+      auto ptr = build_InstGEP(lval, {CONST0, CONST0}, _state.current_bb);
+      auto pointed_type = std::dynamic_pointer_cast<PointerType>(ptr->type)->pointed_type;
+      ValuePtr_t offset = ConstantInt::make_shared(0);
+      auto exp_list = ctx->exp();
+      // calculate offset by hand: offset = (offset + exp[i]) * dim_size[i]
+      for (int i = 0; i < exp_list.size() - 1; ++i) {
+        sysy_assert(typeid(pointed_type) == typeid(std::shared_ptr<ArrayType>));
+        auto array_type = std::dynamic_pointer_cast<ArrayType>(pointed_type);
+        auto exp_val = any_to_Value(visitExp(exp_list[i]));
+        auto dim_size = ConstantInt::make_shared(array_type->element_count);
+        auto inst_add = build_InstBinary(InstTag::Add, offset, exp_val, _state.current_bb);
+        auto inst_mul = build_InstBinary(InstTag::Mul, inst_add, dim_size, _state.current_bb);
+        offset = inst_mul;
+        pointed_type = array_type->element_type;
+        ptr = build_InstGEP(ptr, {CONST0, CONST0}, _state.current_bb);
+      }
+      auto exp_val = any_to_Value(visitExp(exp_list.back()));
+      auto inst_add = build_InstBinary(InstTag::Add, offset, exp_val, _state.current_bb);
+      offset = inst_add; // finally, we get the offset
+      pointed_type = std::dynamic_pointer_cast<PointerType>(ptr->type)->pointed_type;
+      if (TypeHelper::isIntegerType(pointed_type)) {
+        // return the address of the array element
+        auto arr_elem_ptr = build_InstGEP(ptr, {offset}, _state.current_bb);
+        return arr_elem_ptr;
+      }
+      else {
+        panic("Should be int");
+      }
+    }
+    default:
+      panic("Unreachable");
     }
   }
   panic("Unreachable");
@@ -494,7 +752,7 @@ std::any Visitor::visitFuncDef(SysyParser::FuncDefContext *ctx) {
   if (ctx->funcFParams()) {
     visitFuncFParams(ctx->funcFParams());
   }
-  visit(ctx->block());
+  visitBlock(ctx->block());
   // add return
   // _scope_tab.leave_scope();
   // TODO: avoid duplicate ret
@@ -507,36 +765,47 @@ std::any Visitor::visitFuncDef(SysyParser::FuncDefContext *ctx) {
   return {};
 }
 
+// @retval: any
+// Directly add to function, rather than return something...
 std::any Visitor::visitFuncFParams(SysyParser::FuncFParamsContext *ctx) {
-  for (auto fparam : ctx->funcFParam()) {
-    auto fparam_type = std::any_cast<TypePtr_t>(visit(fparam));
-    auto fparam_name = fparam->getText();
-    auto fparam_ptr = std::make_shared<FParam>(fparam_name, fparam_type);
-    _state.current_func->fparam_list.push_back(fparam_ptr);
-    if (fparam->LBRACKET().empty()) {
-      auto alloca = build_InstAlloca(TypeHelper::TYPE_I32, false, _state.current_bb);
-      auto store = build_InstStore(fparam_ptr, alloca, _state.current_bb);
-      _scope_tab.push_name(fparam_name, alloca);
-      _state.current_func->fparam_list.push_back(fparam_ptr);
-    }
-    else {
-      panic("To be implemented");
-    }
+  for (auto fparam_ctx : ctx->funcFParam()) {
+    auto fparam_type = std::any_cast<TypePtr_t>(visitFuncFParam(fparam_ctx));
+    auto fparam_name = fparam_ctx->getText();
+    auto fparam = std::make_shared<FParam>(fparam_name, fparam_type);
+    _state.current_func->fparam_list.push_back(fparam);
+    auto alloca_ = build_InstAlloca(fparam_type, _state.current_bb);
+    build_InstStore(fparam, alloca_, _state.current_bb);
+    _scope_tab.push_name(fparam_name, alloca_);
+    _state.current_func->fparam_list.push_back(fparam);
   }
   return {};
 }
 
+// funcFParam: bType IDENT ('[' ']' ('[' exp ']')*)?;
 std::any Visitor::visitFuncFParam(SysyParser::FuncFParamContext *ctx) {
   if (ctx->LBRACKET().empty()) {
+    // int type
     return {TypeHelper::TYPE_I32};
   }
-  panic("To be implemented");
+  else {
+    // array type
+    std::vector<int> dim_list; // the first dim must be empty, though
+    for (auto exp_ctx : ctx->exp()) {
+      _state.isConstInt = true;
+      auto exp_val = std::dynamic_pointer_cast<ConstantInt>(any_to_Value(visitExp(exp_ctx)));
+      _state.isConstInt = false;
+      dim_list.push_back(exp_val->value);
+    }
+    auto array_type = ArrayType::build_from_list(dim_list);
+    auto true_array_type = std::make_shared<PointerType>(array_type);
+    return {true_array_type};
+  }
 }
 
 std::any Visitor::visitBlock(SysyParser::BlockContext *ctx) {
   _scope_tab.enter_scope();
   for (auto block_item : ctx->blockItem()) {
-    visit(block_item);
+    visitBlockItem(block_item);
   }
   _scope_tab.leave_scope();
   return {};
@@ -556,8 +825,8 @@ stmt: lVal '=' exp ';'                      # assignStmt
 */
 
 std::any Visitor::visitAssignStmt(SysyParser::AssignStmtContext *ctx) {
-  auto lval = any_to_Value(visit(ctx->lVal()));
-  auto rhs = any_to_Value(visit(ctx->exp()));
+  auto lval = any_to_Value(visitLVal(ctx->lVal()));
+  auto rhs = any_to_Value(visitExp(ctx->exp()));
   auto store = build_InstStore(rhs, lval, _state.current_bb);
   return {};
 }