diff --git a/src/include/midend/IR.h b/src/include/midend/IR.h
index 901a3b7..91d7f72 100644
--- a/src/include/midend/IR.h
+++ b/src/include/midend/IR.h
@@ -695,15 +695,13 @@ class Instruction : public User {
     kCondBr = 0x1UL << 30,
     kBr = 0x1UL << 31,
     kReturn = 0x1UL << 32,
+    kUnreachable = 0x1UL << 32,  ///< Unreachable instruction, used for optimization purposes
     // mem op
-    kAlloca = 0x1UL << 33,
-    kLoad = 0x1UL << 34,
-    kStore = 0x1UL << 35,
-    kGetElementPtr = 0x1UL << 36,
-    kMemset = 0x1UL << 37,
-    // kGetSubArray = 0x1UL << 38,
-    // Constant Kind removed as Constants are now Values, not Instructions.
-    // kConstant = 0x1UL << 37, // Conflicts with kMemset if kept as is
+    kAlloca = 0x1UL << 34,
+    kLoad = 0x1UL << 35,
+    kStore = 0x1UL << 36,
+    kGetElementPtr = 0x1UL << 37,
+    kMemset = 0x1UL << 38,
     // phi
     kPhi = 0x1UL << 39,
     kBitItoF = 0x1UL << 40,
@@ -852,6 +850,7 @@ public:
   }
   bool isUnconditional() const { return kind == kBr; }
   bool isConditional() const { return kind == kCondBr; }
+  bool isCondBr() const { return kind == kCondBr; }
   bool isPhi() const { return kind == kPhi; }
   bool isAlloca() const { return kind == kAlloca; }
   bool isLoad() const { return kind == kLoad; }
@@ -894,6 +893,9 @@ class PhiInst : public Instruction {
  public:
   Value* getValue(unsigned k) const {return getOperand(2 * k);}  ///< 获取位置为k的值
   BasicBlock* getBlock(unsigned k) const {return dynamic_cast<BasicBlock*>(getOperand(2 * k + 1));}
+  //增加llvm同名方法实现获取value和block
+  Value* getIncomingValue(unsigned k) const {return getOperand(2 * k);}  ///< 获取位置为k的值
+  BasicBlock* getIncomingBlock(unsigned k) const {return dynamic_cast<BasicBlock*>(getOperand(2 * k + 1));}
 
   auto& getincomings() const {return blk2val;}  ///< 获取所有的基本块和对应的值
 
@@ -1117,6 +1119,14 @@ public:
 
 }; // class CondBrInst
 
+class UnreachableInst : public Instruction {
+public:
+  // 构造函数：设置指令类型为 kUnreachable
+  explicit UnreachableInst(const std::string& name, BasicBlock *parent = nullptr)
+      : Instruction(kUnreachable, Type::getVoidType(), parent, "") {}
+
+};
+
 //! Allocate memory for stack variables, used for non-global variable declartion
 class AllocaInst : public Instruction {
   friend class IRBuilder;
diff --git a/src/include/midend/IRBuilder.h b/src/include/midend/IRBuilder.h
index 760ef85..f761d57 100644
--- a/src/include/midend/IRBuilder.h
+++ b/src/include/midend/IRBuilder.h
@@ -239,19 +239,25 @@ class IRBuilder {
     block->getInstructions().emplace(position, inst);
     return inst;
   }  ///< 创建return指令
-  UncondBrInst * createUncondBrInst(BasicBlock *thenBlock, const std::vector<Value *> &args) {
+  UncondBrInst * createUncondBrInst(BasicBlock *thenBlock, const std::vector<Value *> &args = {}) {
     auto inst = new UncondBrInst(thenBlock, args, block);
     assert(inst);
     block->getInstructions().emplace(position, inst);
     return inst;
   }  ///< 创建无条件指令
   CondBrInst * createCondBrInst(Value *condition, BasicBlock *thenBlock, BasicBlock *elseBlock,
-                        const std::vector<Value *> &thenArgs, const std::vector<Value *> &elseArgs) {
+                        const std::vector<Value *> &thenArgs = {}, const std::vector<Value *> &elseArgs = {}) {
     auto inst = new CondBrInst(condition, thenBlock, elseBlock, thenArgs, elseArgs, block);
     assert(inst);
     block->getInstructions().emplace(position, inst);
     return inst;
   }  ///< 创建条件跳转指令
+  UnreachableInst * createUnreachableInst(const std::string &name = "") {
+    auto inst = new UnreachableInst(name, block);
+    assert(inst);
+    block->getInstructions().emplace(position, inst);
+    return inst;
+  }  ///< 创建不可达指令
   AllocaInst * createAllocaInst(Type *type, const std::vector<Value *> &dims = {}, const std::string &name = "") {
     auto inst = new AllocaInst(type, dims, block, name);
     assert(inst);