diff --git a/src/include/midend/IR.h b/src/include/midend/IR.h
index b71f02b..f7940aa 100644
--- a/src/include/midend/IR.h
+++ b/src/include/midend/IR.h
@@ -1431,14 +1431,14 @@ protected:
     auto it = std::find_if(blocks.begin(), blocks.end(),
                            [before](const std::unique_ptr<BasicBlock> &ptr) { return ptr.get() == before; });
     if (it != blocks.end()) {
-      blocks.emplace(it, new BasicBlock(this, name));
-      return it->get();  // 返回新添加的基本块指针
+      auto newblk = blocks.emplace(it, std::make_unique<BasicBlock>(this, name));
+      return newblk->get();  // 返回新添加的基本块指针
     }
     assert(false && "BasicBlock to insert before not found!"); 
     return nullptr;  // 如果没有找到指定的基本块，则返回nullptr
   }  ///< 添加一个新的基本块到某个基本块之前
   BasicBlock* addBasicBlock(const std::string &name = "") {
-    blocks.emplace_back(new BasicBlock(this, name));
+    blocks.emplace_back(std::make_unique<BasicBlock>(this, name));
     return blocks.back().get();
   }
   BasicBlock* addBasicBlock(BasicBlock *block) {
diff --git a/src/include/midend/Pass/Optimize/LoopNormalization.h b/src/include/midend/Pass/Optimize/LoopNormalization.h
index ef65ae3..34b67f0 100644
--- a/src/include/midend/Pass/Optimize/LoopNormalization.h
+++ b/src/include/midend/Pass/Optimize/LoopNormalization.h
@@ -104,7 +104,7 @@ private:
    * @param preheader 新创建的前置块
    * @param header 循环头部
    */
-  void redirectExternalPredecessors(Loop* loop, BasicBlock* preheader, BasicBlock* header);
+  void redirectExternalPredecessors(Loop* loop, BasicBlock* preheader, BasicBlock* header, const std::vector<BasicBlock*>& externalPreds);
   
   /**
    * 为前置块生成合适的名称
diff --git a/src/midend/IR.cpp b/src/midend/IR.cpp
index 7879816..5b2c258 100644
--- a/src/midend/IR.cpp
+++ b/src/midend/IR.cpp
@@ -762,7 +762,7 @@ void BinaryInst::print(std::ostream &os) const {
     printOperand(os, getLhs());
     os << ", ";
     printOperand(os, getRhs());
-    os << "\n  ";
+    os << "\n    ";
     printVarName(os, this) << " = zext i1 %" << tmpName << " to i32";
   } else if (kind == kFCmpEQ || kind == kFCmpNE || kind == kFCmpLT || 
              kind == kFCmpGT || kind == kFCmpLE || kind == kFCmpGE) {
@@ -777,7 +777,7 @@ void BinaryInst::print(std::ostream &os) const {
     printOperand(os, getLhs());
     os << ", ";
     printOperand(os, getRhs());
-    os << "\n  ";
+    os << "\n    ";
     printVarName(os, this) << " = zext i1 %" << tmpName << " to i32";
   } else {
     // 算术和逻辑指令
diff --git a/src/midend/Pass/Optimize/LoopNormalization.cpp b/src/midend/Pass/Optimize/LoopNormalization.cpp
index 4996304..deb95ec 100644
--- a/src/midend/Pass/Optimize/LoopNormalization.cpp
+++ b/src/midend/Pass/Optimize/LoopNormalization.cpp
@@ -147,7 +147,7 @@ BasicBlock* LoopNormalizationPass::createPreheaderForLoop(Loop* loop) {
   
   // 创建新的前置块
   Function* parentFunction = header->getParent();
-  BasicBlock* preheader = parentFunction->addBasicBlock(preheaderName);
+  BasicBlock* preheader = parentFunction->addBasicBlock(preheaderName, header);
   
   if (!preheader) {
     if (DEBUG)
@@ -163,8 +163,12 @@ BasicBlock* LoopNormalizationPass::createPreheaderForLoop(Loop* loop) {
   preheader->addSuccessor(header);
   header->addPredecessor(preheader);
 
+  if(DEBUG) {
+    std::cout << "    Created preheader " << preheader->getName() 
+              << " with unconditional branch to " << header->getName() << std::endl;
+  }
   // 重定向外部前驱到新的前置块
-  redirectExternalPredecessors(loop, preheader, header);
+  redirectExternalPredecessors(loop, preheader, header, externalPreds);
 
   // 更新PHI节点
   updatePhiNodesForPreheader(header, preheader, externalPreds);
@@ -228,8 +232,9 @@ void LoopNormalizationPass::updateDominatorRelations(BasicBlock* newBlock, Loop*
   }
 }
 
-void LoopNormalizationPass::redirectExternalPredecessors(Loop* loop, BasicBlock* preheader, BasicBlock* header) {
-  std::vector<BasicBlock*> externalPreds = getExternalPredecessors(loop);
+void LoopNormalizationPass::redirectExternalPredecessors(Loop* loop, BasicBlock* preheader, BasicBlock* header, 
+                                                         const std::vector<BasicBlock*>& externalPreds) {
+  // std::vector<BasicBlock*> externalPreds = getExternalPredecessors(loop);
   
   if (DEBUG) {
     std::cout << "    Redirecting " << externalPreds.size() << " external predecessors" << std::endl;
@@ -247,6 +252,10 @@ void LoopNormalizationPass::redirectExternalPredecessors(Loop* loop, BasicBlock*
     if (auto* br = dynamic_cast<UncondBrInst*>(terminator)) {
       // 无条件跳转
       if (br->getBlock() == header) {
+        if(DEBUG){
+          std::cout << "      Updating unconditional branch from " << br->getBlock()->getName()
+                    << " to " << preheader->getName() << std::endl;
+        }
         // 需要更新操作数
         br->setOperand(0, preheader);
         // 更新CFG关系
@@ -255,9 +264,6 @@ void LoopNormalizationPass::redirectExternalPredecessors(Loop* loop, BasicBlock*
         pred->removeSuccessor(header);
         pred->addSuccessor(preheader);
         
-        if (DEBUG)
-          std::cout << "      Updated unconditional branch from " << pred->getName() 
-                    << " to " << preheader->getName() << std::endl;
       }
     } else if (auto* condBr = dynamic_cast<CondBrInst*>(terminator)) {
       // 条件跳转
@@ -288,7 +294,7 @@ void LoopNormalizationPass::redirectExternalPredecessors(Loop* loop, BasicBlock*
 
 std::string LoopNormalizationPass::generatePreheaderName(Loop* loop) {
   std::ostringstream oss;
-  oss << loop->getName() << ".preheader";
+  oss << loop->getName() << "_preheader";
   return oss.str();
 }