diff --git a/src/DeadCodeElimination.cpp b/src/DeadCodeElimination.cpp
index 9abca1c..ffe6022 100644
--- a/src/DeadCodeElimination.cpp
+++ b/src/DeadCodeElimination.cpp
@@ -1,8 +1,9 @@
 #include "DeadCodeElimination.h"
+#include <iostream>
 
+extern int DEBUG;
 namespace sysy {
 
-
 void DeadCodeElimination::runDCEPipeline() {
   const auto& functions = pModule->getFunctions();
   for (const auto& function : functions) {
@@ -58,6 +59,10 @@ void DeadCodeElimination::eliminateDeadStores(Function* func, bool& changed) {
 
       if (changetag) {
         changed = true;
+        if(DEBUG){
+          std::cout << "=== Dead Store Found ===\n";
+          SysYPrinter::printInst(storeInst);
+        }
         usedelete(storeInst);
         iter = instrs.erase(iter);
       } else {
@@ -76,6 +81,10 @@ void DeadCodeElimination::eliminateDeadLoads(Function* func, bool& changed) {
       if (inst->isBinary() || inst->isUnary() || inst->isLoad()) {
         if (inst->getUses().empty()) {
           changed = true;
+          if(DEBUG){
+            std::cout << "=== Dead Load Binary Unary Found ===\n";
+            SysYPrinter::printInst(inst);
+          }
           usedelete(inst);
           iter = instrs.erase(iter);
           continue;
@@ -101,6 +110,10 @@ void DeadCodeElimination::eliminateDeadAllocas(Function* func, bool& changed) {
                       func->getEntryBlock()->getArguments().end(),
                       allocaInst) == func->getEntryBlock()->getArguments().end()) {
           changed = true;
+          if(DEBUG){
+            std::cout << "=== Dead Alloca Found ===\n";
+            SysYPrinter::printInst(inst);
+          }
           usedelete(inst);
           iter = instrs.erase(iter);
           continue;
@@ -116,8 +129,12 @@ void DeadCodeElimination::eliminateDeadIndirectiveAllocas(Function* func, bool&
   FunctionAnalysisInfo* funcInfo = pCFA->getFunctionAnalysisInfo(func);
   for (auto it = funcInfo->getIndirectAllocas().begin(); it != funcInfo->getIndirectAllocas().end();) {
     auto &allocaInst = *it;
-    if (allocaInst->getUses().empty()) {
+    if (allocaInst->getUses().empty()) {  
       changed = true;
+      if(DEBUG){
+        std::cout << "=== Dead Indirect Alloca Found ===\n";
+        SysYPrinter::printInst(allocaInst.get());
+      }
       it = funcInfo->getIndirectAllocas().erase(it);
     } else {
       ++it;
@@ -132,6 +149,10 @@ void DeadCodeElimination::eliminateDeadGlobals(bool& changed) {
     auto& global = *it;
     if (global->getUses().empty()) {
       changed = true;
+      if(DEBUG){
+        std::cout << "=== Dead Global Found ===\n";
+        SysYPrinter::printValue(global.get());
+      }
       it = globals.erase(it);
     } else {
       ++it;
@@ -207,6 +228,12 @@ void DeadCodeElimination::eliminateDeadRedundantLoadStore(Function* func, bool&
                       // 可以优化直接把prevStorePointer的值存到nextStorePointer
                       changed = true;
                       nextStore->setOperand(0, prevStoreValue);
+                      if(DEBUG){
+                        std::cout << "=== Dead Store Load Store Found(now only del Load) ===\n";
+                        SysYPrinter::printInst(prevStore);
+                        SysYPrinter::printInst(loadInst);
+                        SysYPrinter::printInst(nextStore);
+                      }
                       usedelete(loadInst);
                       iter = instrs.erase(iter);
                       // 删除 prevStore 这里是不是可以留给删除无用store处理？
diff --git a/src/SysYIRGenerator.cpp b/src/SysYIRGenerator.cpp
index 86e19e7..7520891 100644
--- a/src/SysYIRGenerator.cpp
+++ b/src/SysYIRGenerator.cpp
@@ -204,6 +204,7 @@ std::any SysYIRGenerator::visitFuncType(SysYParser::FuncTypeContext *ctx) {
 std::any SysYIRGenerator::visitFuncDef(SysYParser::FuncDefContext *ctx){
   // 更新作用域
   module->enterNewScope();
+  HasReturnInst = false;
 
   auto name = ctx->Ident()->getText();
   std::vector<Type *> paramTypes;
@@ -243,6 +244,18 @@ std::any SysYIRGenerator::visitFuncDef(SysYParser::FuncDefContext *ctx){
     visitBlockItem(item);
   }
 
+  if(HasReturnInst == false) {
+    // 如果没有return语句，则默认返回0
+    if (returnType != Type::getVoidType()) {
+      Value* returnValue = ConstantValue::get(0);
+      if (returnType == Type::getFloatType()) {
+        returnValue = ConstantValue::get(0.0f);
+      }
+      builder.createReturnInst(returnValue);
+    } else {
+      builder.createReturnInst();
+    }
+  }
   module->leaveScope();
 
   return std::any();
@@ -478,6 +491,7 @@ std::any SysYIRGenerator::visitReturnStmt(SysYParser::ReturnStmtContext *ctx) {
       }
     }
   builder.createReturnInst(returnValue);
+  HasReturnInst = true;
   return std::any();
 }
 
diff --git a/src/SysYIROptPre.cpp b/src/SysYIROptPre.cpp
index 41af234..fb05cb7 100644
--- a/src/SysYIROptPre.cpp
+++ b/src/SysYIROptPre.cpp
@@ -4,6 +4,7 @@
 #include <map>
 #include <memory>
 #include <string>
+#include <iostream>
 #include "IR.h"
 #include "IRBuilder.h"
 
@@ -458,11 +459,13 @@ void SysYOptPre::SysYAddReturn() {
         // 如果基本块没有后继块，则添加一个返回指令
         if (block->getNumInstructions() == 0) {
           pBuilder->setPosition(block.get(), block->end());
-          pBuilder->createReturnInst({});
+          pBuilder->createReturnInst();
         }
         auto thelastinst = block->getInstructions().end();
         --thelastinst;
         if (thelastinst->get()->getKind() != Instruction::kReturn) {
+          // std::cout << "Warning: Function " << func->getName() << " has no return instruction, adding default return." << std::endl;
+
           pBuilder->setPosition(block.get(), block->end());
           // TODO: 如果int float函数缺少返回值是否需要报错
           if (func->getReturnType()->isInt()) {
@@ -470,7 +473,7 @@ void SysYOptPre::SysYAddReturn() {
           } else if (func->getReturnType()->isFloat()) {
             pBuilder->createReturnInst(ConstantValue::get(0.0F));
           } else {
-            pBuilder->createReturnInst({});
+            pBuilder->createReturnInst();
           }
         }
       }
diff --git a/src/include/DeadCodeElimination.h b/src/include/DeadCodeElimination.h
index 2d614bd..72b9935 100644
--- a/src/include/DeadCodeElimination.h
+++ b/src/include/DeadCodeElimination.h
@@ -2,6 +2,8 @@
 
 #include "IR.h"
 #include "SysYIRAnalyser.h"
+#include "SysYIRPrinter.h"
+
 namespace sysy {
 
 class DeadCodeElimination {
diff --git a/src/include/SysYIRGenerator.h b/src/include/SysYIRGenerator.h
index 445a856..fe309e8 100644
--- a/src/include/SysYIRGenerator.h
+++ b/src/include/SysYIRGenerator.h
@@ -62,6 +62,8 @@ private:
 public:
   SysYIRGenerator() = default;
 
+  bool HasReturnInst;
+
 public:
   Module *get() const { return module.get(); }
   IRBuilder *getBuilder(){ return &builder; }
diff --git a/src/include/SysYIRPrinter.h b/src/include/SysYIRPrinter.h
index 114fb05..bfd78bd 100644
--- a/src/include/SysYIRPrinter.h
+++ b/src/include/SysYIRPrinter.h
@@ -15,15 +15,16 @@ public:
 public:
     void printIR();
     void printGlobalVariable();
-    void printFunction(Function *function);
-    void printInst(Instruction *pInst);
-    void printType(Type *type);
-    void printValue(Value *value);
+    
 
 public:
+    static void printFunction(Function *function);
+    static void printInst(Instruction *pInst);
+    static void printType(Type *type);
+    static void printValue(Value *value);
     static std::string getOperandName(Value *operand);
-    std::string getTypeString(Type *type);
-    std::string getValueName(Value *value);
+    static std::string getTypeString(Type *type);
+    static std::string getValueName(Value *value);
 };
 
 }  // namespace sysy