diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 373ab50..2cf20cb 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,8 +1,6 @@
 # src/ 子目录构建脚本：各子目录独立维护 CMakeLists.txt，并在此聚合链接
 
 add_subdirectory(utils)
-add_subdirectory(ast)
-add_subdirectory(sem)
 add_subdirectory(ir)
 add_subdirectory(frontend)
 add_subdirectory(irgen)
@@ -13,7 +11,6 @@ add_executable(compiler
 )
 target_link_libraries(compiler PRIVATE
   frontend
-  sem
   irgen
   mir
   utils
diff --git a/src/ast/AstNodes.cpp b/src/ast/AstNodes.cpp
deleted file mode 100644
index 380e36e..0000000
--- a/src/ast/AstNodes.cpp
+++ /dev/null
@@ -1,29 +0,0 @@
-
-// AST 节点定义与实现：
-// - 表达式、语句、声明、函数、类型等节点
-// - 支持后续阶段在节点上附加信息（类型、符号绑定、常量值等）
-#include "ast/AstNodes.h"
-
-#include <utility>
-
-namespace ast {
-
-NumberExpr::NumberExpr(int v) : value(v) {}
-
-VarExpr::VarExpr(std::string n) : name(std::move(n)) {}
-
-BinaryExpr::BinaryExpr(BinaryOp op, std::shared_ptr<Expr> lhs,
-                       std::shared_ptr<Expr> rhs)
-    : op(op), lhs(std::move(lhs)), rhs(std::move(rhs)) {}
-
-ReturnStmt::ReturnStmt(std::shared_ptr<Expr> v) : value(std::move(v)) {}
-
-VarDecl::VarDecl(std::string n, std::shared_ptr<Expr> i)
-    : name(std::move(n)), init(std::move(i)) {}
-
-FuncDef::FuncDef(std::string n, std::shared_ptr<Block> b)
-    : name(std::move(n)), body(std::move(b)) {}
-
-CompUnit::CompUnit(std::shared_ptr<FuncDef> f) : func(std::move(f)) {}
-
-}  // namespace ast
diff --git a/src/ast/AstNodes.h b/src/ast/AstNodes.h
deleted file mode 100644
index cfe5908..0000000
--- a/src/ast/AstNodes.h
+++ /dev/null
@@ -1,70 +0,0 @@
-
-#pragma once
-
-#include <iosfwd>
-#include <memory>
-#include <string>
-#include <vector>
-
-namespace ast {
-
-enum class BinaryOp { Add, Sub, Mul, Div };
-
-struct Expr {
-  virtual ~Expr() = default;
-};
-
-struct NumberExpr : Expr {
-  int value{};
-  explicit NumberExpr(int v);
-};
-
-struct VarExpr : Expr {
-  std::string name;
-  explicit VarExpr(std::string n);
-};
-
-struct BinaryExpr : Expr {
-  BinaryOp op;
-  std::shared_ptr<Expr> lhs;
-  std::shared_ptr<Expr> rhs;
-  BinaryExpr(BinaryOp op, std::shared_ptr<Expr> lhs, std::shared_ptr<Expr> rhs);
-};
-
-struct Stmt {
-  virtual ~Stmt() = default;
-};
-
-struct ReturnStmt : Stmt {
-  std::shared_ptr<Expr> value;
-  explicit ReturnStmt(std::shared_ptr<Expr> v);
-};
-
-struct VarDecl {
-  std::string name;
-  std::shared_ptr<Expr> init;  // nullptr if no initializer
-  VarDecl(std::string n, std::shared_ptr<Expr> i);
-};
-
-struct Block {
-  std::vector<std::shared_ptr<VarDecl>> varDecls;
-  std::vector<std::shared_ptr<Stmt>> stmts;
-};
-
-struct FuncDef {
-  std::string name;
-  std::shared_ptr<Block> body;
-  FuncDef(std::string n, std::shared_ptr<Block> b);
-};
-
-struct CompUnit {
-  std::shared_ptr<FuncDef> func;
-  explicit CompUnit(std::shared_ptr<FuncDef> f);
-};
-
-// 调试打印
-void PrintAST(const CompUnit& cu);
-// 导出 AST 为 Graphviz DOT。
-void PrintASTDot(const CompUnit& cu, std::ostream& os);
-
-}  // namespace ast
diff --git a/src/ast/AstPrinter.cpp b/src/ast/AstPrinter.cpp
deleted file mode 100644
index 89510ba..0000000
--- a/src/ast/AstPrinter.cpp
+++ /dev/null
@@ -1,198 +0,0 @@
-// 简单 AST 调试打印，便于前端验证。
-
-#include "ast/AstNodes.h"
-
-#include <iostream>
-#include <ostream>
-#include <string>
-
-namespace ast {
-
-static void PrintIndent(int depth) {
-  for (int i = 0; i < depth; ++i) std::cout << "  ";
-}
-
-static void PrintLine(int depth, const std::string& text) {
-  PrintIndent(depth);
-  std::cout << text << "\n";
-}
-
-static void DumpExpr(const Expr* expr, int depth) {
-  if (!expr) {
-    PrintLine(depth, "NullExpr");
-    return;
-  }
-
-  if (auto num = dynamic_cast<const NumberExpr*>(expr)) {
-    PrintLine(depth, "NumberExpr value=" + std::to_string(num->value));
-    return;
-  }
-  if (auto var = dynamic_cast<const VarExpr*>(expr)) {
-    PrintLine(depth, "VarExpr name=" + var->name);
-    return;
-  }
-  if (auto bin = dynamic_cast<const BinaryExpr*>(expr)) {
-    const char* op = "?";
-    switch (bin->op) {
-      case BinaryOp::Add:
-        op = "Add";
-        break;
-      case BinaryOp::Sub:
-        op = "Sub";
-        break;
-      case BinaryOp::Mul:
-        op = "Mul";
-        break;
-      case BinaryOp::Div:
-        op = "Div";
-        break;
-    }
-    PrintLine(depth, std::string("BinaryExpr op=") + op);
-    DumpExpr(bin->lhs.get(), depth + 1);
-    DumpExpr(bin->rhs.get(), depth + 1);
-    return;
-  }
-
-  PrintLine(depth, "UnknownExpr");
-}
-
-void PrintAST(const CompUnit& cu) {
-  PrintLine(0, "CompUnit");
-  if (!cu.func) {
-    PrintLine(1, "<empty>");
-    std::cout << "\n";
-    return;
-  }
-
-  PrintLine(1, "FuncDef name=" + cu.func->name);
-  const auto& body = cu.func->body;
-  if (!body) {
-    PrintLine(2, "Block <null>");
-    return;
-  }
-
-  PrintLine(2, "Block");
-  for (const auto& decl : body->varDecls) {
-    PrintLine(3, "VarDecl name=" + decl->name);
-    if (decl->init) {
-      PrintLine(4, "Init");
-      DumpExpr(decl->init.get(), 5);
-    }
-  }
-  for (const auto& stmt : body->stmts) {
-    if (auto ret = dynamic_cast<ReturnStmt*>(stmt.get())) {
-      PrintLine(3, "ReturnStmt");
-      DumpExpr(ret->value.get(), 4);
-    } else {
-      PrintLine(3, "UnknownStmt");
-    }
-  }
-  std::cout << "\n";
-}
-
-namespace {
-
-std::string EscapeDotLabel(const std::string& s) {
-  std::string out;
-  out.reserve(s.size());
-  for (char c : s) {
-    if (c == '\\' || c == '"') out.push_back('\\');
-    out.push_back(c);
-  }
-  return out;
-}
-
-class DotWriter {
- public:
-  explicit DotWriter(std::ostream& os) : os_(os) {}
-
-  int AddNode(const std::string& label) {
-    int id = next_id_++;
-    os_ << "  n" << id << " [label=\"" << EscapeDotLabel(label) << "\"];\n";
-    return id;
-  }
-
-  void AddEdge(int from, int to) { os_ << "  n" << from << " -> n" << to << ";\n"; }
-
- private:
-  std::ostream& os_;
-  int next_id_ = 0;
-};
-
-int EmitExpr(const Expr* expr, DotWriter& dot) {
-  if (!expr) return dot.AddNode("NullExpr");
-
-  if (auto num = dynamic_cast<const NumberExpr*>(expr)) {
-    return dot.AddNode("Number(" + std::to_string(num->value) + ")");
-  }
-  if (auto var = dynamic_cast<const VarExpr*>(expr)) {
-    return dot.AddNode("Var(" + var->name + ")");
-  }
-  if (auto bin = dynamic_cast<const BinaryExpr*>(expr)) {
-    const char* op = "?";
-    switch (bin->op) {
-      case BinaryOp::Add:
-        op = "Add";
-        break;
-      case BinaryOp::Sub:
-        op = "Sub";
-        break;
-      case BinaryOp::Mul:
-        op = "Mul";
-        break;
-      case BinaryOp::Div:
-        op = "Div";
-        break;
-    }
-    int id = dot.AddNode(std::string("Binary(") + op + ")");
-    int lhs = EmitExpr(bin->lhs.get(), dot);
-    int rhs = EmitExpr(bin->rhs.get(), dot);
-    dot.AddEdge(id, lhs);
-    dot.AddEdge(id, rhs);
-    return id;
-  }
-  return dot.AddNode("UnknownExpr");
-}
-
-}  // namespace
-
-void PrintASTDot(const CompUnit& cu, std::ostream& os) {
-  os << "digraph AST {\n";
-  os << "  rankdir=TB;\n";
-  os << "  node [shape=box, fontname=\"Courier\"];\n";
-
-  DotWriter dot(os);
-  int cu_id = dot.AddNode("CompUnit");
-  if (cu.func) {
-    int func_id = dot.AddNode("FuncDef(" + cu.func->name + ")");
-    dot.AddEdge(cu_id, func_id);
-    if (cu.func->body) {
-      int block_id = dot.AddNode("Block");
-      dot.AddEdge(func_id, block_id);
-
-      for (const auto& decl : cu.func->body->varDecls) {
-        int decl_id = dot.AddNode("VarDecl(" + decl->name + ")");
-        dot.AddEdge(block_id, decl_id);
-        if (decl->init) {
-          int init_id = EmitExpr(decl->init.get(), dot);
-          dot.AddEdge(decl_id, init_id);
-        }
-      }
-
-      for (const auto& stmt : cu.func->body->stmts) {
-        if (auto ret = dynamic_cast<ReturnStmt*>(stmt.get())) {
-          int ret_id = dot.AddNode("Return");
-          dot.AddEdge(block_id, ret_id);
-          int value_id = EmitExpr(ret->value.get(), dot);
-          dot.AddEdge(ret_id, value_id);
-        } else {
-          int stmt_id = dot.AddNode("Stmt");
-          dot.AddEdge(block_id, stmt_id);
-        }
-      }
-    }
-  }
-  os << "}\n";
-}
-
-}  // namespace ast
diff --git a/src/ast/CMakeLists.txt b/src/ast/CMakeLists.txt
deleted file mode 100644
index b084694..0000000
--- a/src/ast/CMakeLists.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-add_library(ast STATIC
-  AstNodes.cpp
-  AstPrinter.cpp
-)
-
-target_link_libraries(ast PUBLIC
-  build_options
-)
diff --git a/src/frontend/AstBuilder.cpp b/src/frontend/AstBuilder.cpp
deleted file mode 100644
index da6b3d9..0000000
--- a/src/frontend/AstBuilder.cpp
+++ /dev/null
@@ -1,114 +0,0 @@
-// 将 parse tree 转换为 AST。
-#include "frontend/AstBuilder.h"
-
-#include <any>
-#include <stdexcept>
-#include <string>
-#include <utility>
-#include <vector>
-
-#include "SysYBaseVisitor.h"
-#include "SysYParser.h"
-#include "ast/AstNodes.h"
-#include "antlr4-runtime.h"
-
-namespace {
-
-using ast::BinaryExpr;
-using ast::BinaryOp;
-using ast::Block;
-using ast::CompUnit;
-using ast::FuncDef;
-using ast::NumberExpr;
-using ast::ReturnStmt;
-using ast::VarDecl;
-using ast::VarExpr;
-
-template <typename T>
-T Take(std::any&& value) {
-  if (auto* ptr = std::any_cast<T>(&value)) {
-    return std::move(*ptr);
-  }
-  throw std::runtime_error("AST 构建失败：类型不匹配");
-}
-
-class Builder : public SysYBaseVisitor {
- public:
-  std::any visitCompUnit(SysYParser::CompUnitContext* ctx) override {
-    auto func = Take<std::shared_ptr<FuncDef>>(visit(ctx->funcDef()));
-    return std::make_shared<CompUnit>(std::move(func));
-  }
-
-  std::any visitFuncDef(SysYParser::FuncDefContext* ctx) override {
-    auto body = Take<std::shared_ptr<Block>>(visit(ctx->block()));
-    return std::make_shared<FuncDef>("main", std::move(body));
-  }
-
-  std::any visitBlock(SysYParser::BlockContext* ctx) override {
-    auto block = std::make_shared<Block>();
-    for (auto stmtCtx : ctx->stmt()) {
-      if (stmtCtx->varDecl()) {
-        block->varDecls.emplace_back(
-            Take<std::shared_ptr<VarDecl>>(visit(stmtCtx->varDecl())));
-      } else if (stmtCtx->returnStmt()) {
-        block->stmts.emplace_back(
-            Take<std::shared_ptr<ReturnStmt>>(visit(stmtCtx->returnStmt())));
-      }
-    }
-    return block;
-  }
-
-  std::any visitVarDecl(SysYParser::VarDeclContext* ctx) override {
-    std::shared_ptr<ast::Expr> init;
-    if (ctx->exp()) {
-      init = Take<std::shared_ptr<ast::Expr>>(visit(ctx->exp()));
-    }
-    return std::make_shared<VarDecl>(ctx->Ident()->getText(), std::move(init));
-  }
-
-  std::any visitReturnStmt(SysYParser::ReturnStmtContext* ctx) override {
-    auto expr = Take<std::shared_ptr<ast::Expr>>(visit(ctx->exp()));
-    return std::make_shared<ReturnStmt>(std::move(expr));
-  }
-
-  std::any visitExp(SysYParser::ExpContext* ctx) override {
-    return visit(ctx->addExp());
-  }
-
-  std::any visitAddExp(SysYParser::AddExpContext* ctx) override {
-    auto node = Take<std::shared_ptr<ast::Expr>>(visit(ctx->primary(0)));
-    for (size_t i = 1; i < ctx->primary().size(); ++i) {
-      auto rhs = Take<std::shared_ptr<ast::Expr>>(visit(ctx->primary(i)));
-      auto opToken = ctx->AddOp(i - 1);
-      BinaryOp op = BinaryOp::Add;
-      if (opToken->getText() == "-") op = BinaryOp::Sub;
-      node = std::make_shared<BinaryExpr>(op, std::move(node), std::move(rhs));
-    }
-    return node;
-  }
-
-  std::any visitPrimary(SysYParser::PrimaryContext* ctx) override {
-    if (ctx->Number()) {
-      std::shared_ptr<ast::Expr> expr =
-          std::make_shared<NumberExpr>(std::stoi(ctx->Number()->getText()));
-      return expr;
-    }
-    if (ctx->Ident()) {
-      std::shared_ptr<ast::Expr> expr =
-          std::make_shared<VarExpr>(ctx->Ident()->getText());
-      return expr;
-    }
-    return visit(ctx->exp());
-  }
-};
-
-}  // namespace
-
-std::shared_ptr<ast::CompUnit> BuildAst(antlr4::tree::ParseTree* tree) {
-  if (!tree) {
-    throw std::runtime_error("parse tree 为空");
-  }
-  Builder visitor;
-  auto result = visitor.visit(tree);
-  return Take<std::shared_ptr<ast::CompUnit>>(std::move(result));
-}
diff --git a/src/frontend/AstBuilder.h b/src/frontend/AstBuilder.h
deleted file mode 100644
index 7607667..0000000
--- a/src/frontend/AstBuilder.h
+++ /dev/null
@@ -1,16 +0,0 @@
-// 将 ANTLR parse tree 转换为内部 AST。
-#pragma once
-
-#include <memory>
-
-namespace antlr4 {
-namespace tree {
-class ParseTree;
-}
-}  // namespace antlr4
-
-namespace ast {
-struct CompUnit;
-}
-
-std::shared_ptr<ast::CompUnit> BuildAst(antlr4::tree::ParseTree* tree);
diff --git a/src/frontend/CMakeLists.txt b/src/frontend/CMakeLists.txt
index 7f6841d..0b54f5b 100644
--- a/src/frontend/CMakeLists.txt
+++ b/src/frontend/CMakeLists.txt
@@ -1,11 +1,9 @@
 add_library(frontend STATIC
   AntlrDriver.cpp
-  AstBuilder.cpp
 )
 
 target_link_libraries(frontend PUBLIC
   build_options
-  ast
   "${ANTLR4_RUNTIME_TARGET}"
 )
 
diff --git a/src/irgen/CMakeLists.txt b/src/irgen/CMakeLists.txt
index e711474..8f0f1e1 100644
--- a/src/irgen/CMakeLists.txt
+++ b/src/irgen/CMakeLists.txt
@@ -8,7 +8,6 @@ add_library(irgen STATIC
 
 target_link_libraries(irgen PUBLIC
   build_options
-  ast
-  sem
+  "${ANTLR4_RUNTIME_TARGET}"
   ir
 )
diff --git a/src/irgen/IRGen.h b/src/irgen/IRGen.h
index e87fd78..fde34c5 100644
--- a/src/irgen/IRGen.h
+++ b/src/irgen/IRGen.h
@@ -1,45 +1,44 @@
-// 将 AST 翻译为极简 IR。
-// 这里提供一个可运行的最小 IR 生成骨架，并把实现拆分到 IRGenFunc/IRGenStmt/IRGenExp/IRGenDecl。
-// 同学可以在对应 .cpp 内进一步完善更多语义。
+// 将 ANTLR parse tree 翻译为极简 IR。
+// 实现拆分在 IRGenFunc/IRGenStmt/IRGenExp/IRGenDecl。
 
 #pragma once
 
 #include <memory>
 #include <string>
 #include <unordered_map>
-#include <vector>
 
+#include "SysYParser.h"
 #include "ir/IR.h"
 
-namespace ast {
-struct CompUnit;
-struct Block;
-struct VarDecl;
-struct Stmt;
-struct Expr;
+namespace antlr4 {
+namespace tree {
+class ParseTree;
 }
+}  // namespace antlr4
 
 namespace ir {
 class Module;
 class Function;
 class IRBuilder;
 class Value;
-class ConstantInt;
 }
 
-// 最小 IR 生成器的内部实现，接口分散在各 IRGen*.cpp。
 class IRGenImpl {
  public:
   explicit IRGenImpl(ir::Module& module);
 
-  void Gen(const ast::CompUnit& ast);
-  std::unique_ptr<ir::Module> TakeModule();
+  void Gen(SysYParser::CompUnitContext& cu);
 
  private:
-  void GenBlock(const ast::Block& block);
-  void GenVarDecl(const ast::VarDecl& decl);
-  void GenStmt(const ast::Stmt& stmt);
-  ir::Value* GenExpr(const ast::Expr& expr);
+  void GenFuncDef(SysYParser::FuncDefContext& func);
+  void GenBlock(SysYParser::BlockContext& block);
+  void GenStmt(SysYParser::StmtContext& stmt);
+  void GenVarDecl(SysYParser::VarDeclContext& decl);
+  void GenReturnStmt(SysYParser::ReturnStmtContext& ret);
+
+  ir::Value* GenExpr(SysYParser::ExpContext& expr);
+  ir::Value* GenAddExpr(SysYParser::AddExpContext& add);
+  ir::Value* GenPrimary(SysYParser::PrimaryContext& primary);
 
   ir::Module& module_;
   ir::Function* func_;
@@ -47,4 +46,4 @@ class IRGenImpl {
   std::unordered_map<std::string, ir::Value*> locals_;
 };
 
-std::unique_ptr<ir::Module> GenerateIR(const ast::CompUnit& ast);
+std::unique_ptr<ir::Module> GenerateIR(antlr4::tree::ParseTree* tree);
diff --git a/src/irgen/IRGenDecl.cpp b/src/irgen/IRGenDecl.cpp
index 099ea0b..d8e54b2 100644
--- a/src/irgen/IRGenDecl.cpp
+++ b/src/irgen/IRGenDecl.cpp
@@ -1,39 +1,36 @@
-// 声明翻译模块：
-// - 处理全局变量与局部变量声明
-// - 处理数组初始化、空间分配与初值生成等
-
 #include "irgen/IRGen.h"
 
-#include <memory>
 #include <stdexcept>
 
-#include "ast/AstNodes.h"
+#include "SysYParser.h"
 #include "ir/IR.h"
 
-void IRGenImpl::GenBlock(const ast::Block& block) {
-  // 先为所有局部变量创建栈槽，使 alloca 聚集在入口块前部。
-  for (const auto& decl : block.varDecls) {
-    auto* slot = builder_.CreateAllocaI32(ir::DefaultContext().NextTemp());
-    locals_[decl->name] = slot;
+void IRGenImpl::GenBlock(SysYParser::BlockContext& block) {
+  for (auto* stmt : block.stmt()) {
+    if (stmt && stmt->varDecl()) {
+      const std::string name = stmt->varDecl()->Ident()->getText();
+      auto* slot = builder_.CreateAllocaI32(ir::DefaultContext().NextTemp());
+      locals_[name] = slot;
+    }
   }
 
-  for (const auto& decl : block.varDecls) {
-    GenVarDecl(*decl);
-  }
-  for (const auto& stmt : block.stmts) {
-    GenStmt(*stmt);
+  for (auto* stmt : block.stmt()) {
+    if (stmt) {
+      GenStmt(*stmt);
+    }
   }
 }
 
-void IRGenImpl::GenVarDecl(const ast::VarDecl& decl) {
-  auto it = locals_.find(decl.name);
+void IRGenImpl::GenVarDecl(SysYParser::VarDeclContext& decl) {
+  const std::string name = decl.Ident()->getText();
+  auto it = locals_.find(name);
   if (it == locals_.end()) {
-    throw std::runtime_error("[irgen] 变量栈槽未创建: " + decl.name);
+    throw std::runtime_error("[irgen] 变量栈槽未创建: " + name);
   }
 
   ir::Value* init = nullptr;
-  if (decl.init) {
-    init = GenExpr(*decl.init);
+  if (decl.exp()) {
+    init = GenExpr(*decl.exp());
   } else {
     init = ir::DefaultContext().GetConstInt(0);
   }
diff --git a/src/irgen/IRGenDriver.cpp b/src/irgen/IRGenDriver.cpp
index d7d1699..2c585f8 100644
--- a/src/irgen/IRGenDriver.cpp
+++ b/src/irgen/IRGenDriver.cpp
@@ -1,19 +1,24 @@
-// 这是一个“可跑”的最小 IR 生成示例，便于对照/调试。
-// IR 生成驱动（Driver）：
-// - 驱动 Visitor 遍历 AST，调度各子模块完成翻译
-// - 统一管理模块级翻译入口与上下文（Module/IRBuilder 等）
-// - 组织函数/语句/表达式/声明等翻译流程
-
 #include "irgen/IRGen.h"
 
 #include <memory>
+#include <stdexcept>
 
-#include "ast/AstNodes.h"
+#include "SysYParser.h"
+#include "antlr4-runtime.h"
 #include "ir/IR.h"
 
-std::unique_ptr<ir::Module> GenerateIR(const ast::CompUnit& ast) {
+std::unique_ptr<ir::Module> GenerateIR(antlr4::tree::ParseTree* tree) {
+  if (!tree) {
+    throw std::runtime_error("[irgen] parse tree 为空");
+  }
+
+  auto* cu = dynamic_cast<SysYParser::CompUnitContext*>(tree);
+  if (!cu) {
+    throw std::runtime_error("[irgen] parse tree 根节点不是 compUnit");
+  }
+
   auto module = std::make_unique<ir::Module>();
   IRGenImpl gen(*module);
-  gen.Gen(ast);
+  gen.Gen(*cu);
   return module;
 }
diff --git a/src/irgen/IRGenExp.cpp b/src/irgen/IRGenExp.cpp
index 2dfc6aa..3b7c7d4 100644
--- a/src/irgen/IRGenExp.cpp
+++ b/src/irgen/IRGenExp.cpp
@@ -1,37 +1,46 @@
-// 表达式翻译模块：
-// - 处理算术运算、比较、逻辑运算、函数调用等表达式
-// - 生成对应的 IR 指令并返回 SSA 值
-
 #include "irgen/IRGen.h"
 
 #include <stdexcept>
 
-#include "ast/AstNodes.h"
+#include "SysYParser.h"
 #include "ir/IR.h"
 
-ir::Value* IRGenImpl::GenExpr(const ast::Expr& expr) {
-  if (auto num = dynamic_cast<const ast::NumberExpr*>(&expr)) {
-    return ir::DefaultContext().GetConstInt(num->value);
+ir::Value* IRGenImpl::GenExpr(SysYParser::ExpContext& expr) {
+  if (!expr.addExp()) {
+    throw std::runtime_error("[irgen] 非法表达式");
   }
-  if (auto var = dynamic_cast<const ast::VarExpr*>(&expr)) {
-    auto it = locals_.find(var->name);
-    if (it == locals_.end()) {
-      throw std::runtime_error("[irgen] 变量未找到: " + var->name);
-    }
-    std::string name = ir::DefaultContext().NextTemp();
-    return builder_.CreateLoad(it->second, name);
+  return GenAddExpr(*expr.addExp());
+}
+
+ir::Value* IRGenImpl::GenAddExpr(SysYParser::AddExpContext& add) {
+  const auto& terms = add.primary();
+  if (terms.empty()) {
+    throw std::runtime_error("[irgen] 空加法表达式");
   }
-  if (auto bin = dynamic_cast<const ast::BinaryExpr*>(&expr)) {
-    auto* lhs = GenExpr(*bin->lhs);
-    auto* rhs = GenExpr(*bin->rhs);
+
+  ir::Value* acc = GenPrimary(*terms[0]);
+  for (size_t i = 1; i < terms.size(); ++i) {
+    ir::Value* rhs = GenPrimary(*terms[i]);
     std::string name = ir::DefaultContext().NextTemp();
-    if (bin->op == ast::BinaryOp::Add) {
-      return builder_.CreateBinary(ir::Opcode::Add, lhs, rhs, name);
-    }
-    if (bin->op == ast::BinaryOp::Sub) {
-      // 当前子集只需要加法，减法复用 add 但保留分支，便于扩展
-      return builder_.CreateBinary(ir::Opcode::Add, lhs, rhs, name);
+    acc = builder_.CreateBinary(ir::Opcode::Add, acc, rhs, name);
+  }
+  return acc;
+}
+
+ir::Value* IRGenImpl::GenPrimary(SysYParser::PrimaryContext& primary) {
+  if (primary.Number()) {
+    return ir::DefaultContext().GetConstInt(std::stoi(primary.Number()->getText()));
+  }
+  if (primary.Ident()) {
+    const std::string name = primary.Ident()->getText();
+    auto it = locals_.find(name);
+    if (it == locals_.end()) {
+      throw std::runtime_error("[irgen] 变量未找到: " + name);
     }
+    return builder_.CreateLoad(it->second, ir::DefaultContext().NextTemp());
+  }
+  if (primary.exp()) {
+    return GenExpr(*primary.exp());
   }
-  throw std::runtime_error("[irgen] 暂不支持的表达式类型");
+  throw std::runtime_error("[irgen] 暂不支持的 primary 形式");
 }
diff --git a/src/irgen/IRGenFunc.cpp b/src/irgen/IRGenFunc.cpp
index e1b4a24..dfbe25f 100644
--- a/src/irgen/IRGenFunc.cpp
+++ b/src/irgen/IRGenFunc.cpp
@@ -1,26 +1,28 @@
-// 函数翻译模块：
-// - 处理函数定义、参数列表与返回值翻译
-// - 创建并填充对应的 IR Function 对象
-
 #include "irgen/IRGen.h"
 
 #include <stdexcept>
 
-#include "ast/AstNodes.h"
+#include "SysYParser.h"
 #include "ir/IR.h"
 
 IRGenImpl::IRGenImpl(ir::Module& module)
-    : module_(module),
-      func_(module_.CreateFunction("main", ir::Type::Int32())),
-      builder_(func_->entry()) {}
+    : module_(module), func_(nullptr), builder_(nullptr) {}
 
-void IRGenImpl::Gen(const ast::CompUnit& ast) {
-  if (!ast.func || !ast.func->body) {
-    throw std::runtime_error("[irgen] AST 不完整：缺少 main 定义");
+void IRGenImpl::Gen(SysYParser::CompUnitContext& cu) {
+  if (!cu.funcDef()) {
+    throw std::runtime_error("[irgen] 缺少 main 定义");
   }
-  GenBlock(*ast.func->body);
+  GenFuncDef(*cu.funcDef());
 }
 
-std::unique_ptr<ir::Module> IRGenImpl::TakeModule() {
-  return std::make_unique<ir::Module>(std::move(module_));
+void IRGenImpl::GenFuncDef(SysYParser::FuncDefContext& func) {
+  if (!func.block()) {
+    throw std::runtime_error("[irgen] 函数体为空");
+  }
+
+  func_ = module_.CreateFunction("main", ir::Type::Int32());
+  builder_.SetInsertPoint(func_->entry());
+  locals_.clear();
+
+  GenBlock(*func.block());
 }
diff --git a/src/irgen/IRGenStmt.cpp b/src/irgen/IRGenStmt.cpp
index 9704f98..bf9a605 100644
--- a/src/irgen/IRGenStmt.cpp
+++ b/src/irgen/IRGenStmt.cpp
@@ -1,19 +1,26 @@
-// 语句翻译模块：
-// - 处理 if/while/return 等控制流构造
-// - 负责基本块创建、分支跳转与控制流收束
-
 #include "irgen/IRGen.h"
 
 #include <stdexcept>
 
-#include "ast/AstNodes.h"
+#include "SysYParser.h"
 #include "ir/IR.h"
 
-void IRGenImpl::GenStmt(const ast::Stmt& stmt) {
-  if (auto ret = dynamic_cast<const ast::ReturnStmt*>(&stmt)) {
-    ir::Value* v = GenExpr(*ret->value);
-    builder_.CreateRet(v);
+void IRGenImpl::GenStmt(SysYParser::StmtContext& stmt) {
+  if (stmt.varDecl()) {
+    GenVarDecl(*stmt.varDecl());
+    return;
+  }
+  if (stmt.returnStmt()) {
+    GenReturnStmt(*stmt.returnStmt());
     return;
   }
   throw std::runtime_error("[irgen] 暂不支持的语句类型");
 }
+
+void IRGenImpl::GenReturnStmt(SysYParser::ReturnStmtContext& ret) {
+  if (!ret.exp()) {
+    throw std::runtime_error("[irgen] return 缺少表达式");
+  }
+  ir::Value* v = GenExpr(*ret.exp());
+  builder_.CreateRet(v);
+}
diff --git a/src/main.cpp b/src/main.cpp
index 121dbb6..609ea67 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,17 +1,12 @@
 #include <exception>
-#include <fstream>
 #include <iostream>
-#include <stdexcept>
 
 #include "frontend/AntlrDriver.h"
-#include "frontend/AstBuilder.h"
 #include "ir/IR.h"
 #include "irgen/IRGen.h"
 #include "mir/MIR.h"
-#include "sem/Sema.h"
 #include "utils/CLI.h"
 #include "utils/Log.h"
-#include "ast/AstNodes.h"
 
 int main(int argc, char** argv) {
   try {
@@ -20,25 +15,15 @@ int main(int argc, char** argv) {
       PrintHelp(std::cout);
       return 0;
     }
+
     auto antlr = ParseFileWithAntlr(opts.input);
-    auto ast = BuildAst(antlr.tree);
     bool need_blank_line = false;
-    if (opts.emit_ast) {
-      ast::PrintAST(*ast);  // 调试 AST
+    if (opts.emit_parse_tree) {
+      std::cout << antlr.tree->toStringTree(antlr.parser.get()) << "\n";
       need_blank_line = true;
     }
-    if (!opts.ast_dot_output.empty()) {
-      std::ofstream dot_out(opts.ast_dot_output);
-      if (!dot_out) {
-        throw std::runtime_error("无法写入 AST DOT 文件: " + opts.ast_dot_output);
-      }
-      ast::PrintASTDot(*ast, dot_out);
-    }
-    ast = RunSema(std::move(ast));
-    // IR 生成：当前使用 IRGenDriver.cpp 里的最小实现，
-    // 同学们可以在 irgen/ 目录下按提示自行完善或替换实现。
-    auto module = GenerateIR(*ast);
 
+    auto module = GenerateIR(antlr.tree);
     if (opts.emit_ir) {
       ir::IRPrinter printer;
       if (need_blank_line) {
diff --git a/src/sem/Sema.cpp b/src/sem/Sema.cpp
index 68e9056..92b960c 100644
--- a/src/sem/Sema.cpp
+++ b/src/sem/Sema.cpp
@@ -19,14 +19,14 @@ class SemaVisitor {
   explicit SemaVisitor(SymbolTable& table) : table_(table) {}
 
   void CheckBlock(const ast::Block& block) {
-    for (const auto& decl : block.varDecls) {
-      table_.Add(decl->name);
-      if (decl->init) CheckExpr(*decl->init);
-    }
-    for (const auto& stmt : block.stmts) {
-      if (auto ret = dynamic_cast<ast::ReturnStmt*>(stmt.get())) {
+    for (const auto& item : block.items) {
+      if (auto decl = dynamic_cast<ast::VarDecl*>(item.get())) {
+        table_.Add(decl->name);
+        if (decl->init) CheckExpr(*decl->init);
+        continue;
+      }
+      if (auto ret = dynamic_cast<ast::ReturnStmt*>(item.get())) {
         CheckExpr(*ret->value);
-                                   
       }
     }
   }
diff --git a/src/utils/CLI.cpp b/src/utils/CLI.cpp
index 31742ac..571750e 100644
--- a/src/utils/CLI.cpp
+++ b/src/utils/CLI.cpp
@@ -15,7 +15,7 @@ CLIOptions ParseCLI(int argc, char** argv) {
 
   if (argc <= 1) {
     throw std::runtime_error(
-        "用法: compiler [--help] [--emit-ast] [--emit-ir] [--emit-asm] [--ast-dot <file.dot>] <input.sy>");
+        "用法: compiler [--help] [--emit-parse-tree] [--emit-ir] [--emit-asm] <input.sy>");
   }
 
   for (int i = 1; i < argc; ++i) {
@@ -25,27 +25,20 @@ CLIOptions ParseCLI(int argc, char** argv) {
       return opt;
     }
 
-    if (std::strcmp(arg, "--ast-dot") == 0) {
-      if (i + 1 >= argc) {
-        throw std::runtime_error("参数错误: --ast-dot 需要一个输出路径");
-      }
-      opt.ast_dot_output = argv[++i];
-      continue;
-    }
-
-    if (std::strcmp(arg, "--emit-ast") == 0) {
+    if (std::strcmp(arg, "--emit-parse-tree") == 0) {
       if (!explicit_emit) {
-        opt.emit_ast = false;
+        opt.emit_parse_tree = false;
         opt.emit_ir = false;
+        opt.emit_asm = false;
         explicit_emit = true;
       }
-      opt.emit_ast = true;
+      opt.emit_parse_tree = true;
       continue;
     }
 
     if (std::strcmp(arg, "--emit-ir") == 0) {
       if (!explicit_emit) {
-        opt.emit_ast = false;
+        opt.emit_parse_tree = false;
         opt.emit_ir = false;
         opt.emit_asm = false;
         explicit_emit = true;
@@ -56,7 +49,7 @@ CLIOptions ParseCLI(int argc, char** argv) {
 
     if (std::strcmp(arg, "--emit-asm") == 0) {
       if (!explicit_emit) {
-        opt.emit_ast = false;
+        opt.emit_parse_tree = false;
         opt.emit_ir = false;
         opt.emit_asm = false;
         explicit_emit = true;
@@ -80,10 +73,9 @@ CLIOptions ParseCLI(int argc, char** argv) {
   if (opt.input.empty() && !opt.show_help) {
     throw std::runtime_error("缺少输入文件：请提供 <input.sy>（使用 --help 查看用法）");
   }
-  if (!opt.emit_ast && !opt.emit_ir && !opt.emit_asm &&
-      opt.ast_dot_output.empty()) {
+  if (!opt.emit_parse_tree && !opt.emit_ir && !opt.emit_asm) {
     throw std::runtime_error(
-        "未选择任何输出：请使用 --emit-ast / --emit-ir / --emit-asm（或使用 --ast-dot 导出图）");
+        "未选择任何输出：请使用 --emit-parse-tree / --emit-ir / --emit-asm");
   }
   return opt;
 }
diff --git a/src/utils/CLI.h b/src/utils/CLI.h
index 10fe377..4b3a781 100644
--- a/src/utils/CLI.h
+++ b/src/utils/CLI.h
@@ -1,12 +1,11 @@
-// 简易命令行解析：支持帮助、输入文件和 AST DOT 导出。
+// 简易命令行解析：支持帮助、输入文件与输出阶段选择。
 #pragma once
 
 #include <string>
 
 struct CLIOptions {
   std::string input;
-  std::string ast_dot_output;
-  bool emit_ast = true;
+  bool emit_parse_tree = false;
   bool emit_ir = true;
   bool emit_asm = false;
   bool show_help = false;
diff --git a/src/utils/Log.cpp b/src/utils/Log.cpp
index b8e3a68..0b8ae78 100644
--- a/src/utils/Log.cpp
+++ b/src/utils/Log.cpp
@@ -10,18 +10,17 @@ void PrintHelp(std::ostream& os) {
   os << "SysY Compiler (课程实验最小可运行示例)\n"
      << "\n"
      << "用法:\n"
-     << "  compiler [--help] [--emit-ast] [--emit-ir] [--emit-asm] [--ast-dot <file.dot>] <input.sy>\n"
+     << "  compiler [--help] [--emit-parse-tree] [--emit-ir] [--emit-asm] <input.sy>\n"
      << "\n"
      << "选项:\n"
      << "  -h, --help        打印帮助信息并退出\n"
-     << "  --emit-ast        仅在显式模式下启用 AST 文本输出\n"
+     << "  --emit-parse-tree 仅在显式模式下启用 ANTLR 语法树输出\n"
      << "  --emit-ir         仅在显式模式下启用 IR 输出\n"
      << "  --emit-asm        仅在显式模式下启用 AArch64 汇编输出\n"
-     << "  --ast-dot <path>  导出 AST Graphviz DOT 到指定文件\n"
      << "\n"
      << "说明:\n"
-     << "  - 默认同时输出 AST 与 IR\n"
-     << "  - 若使用 --emit-ast/--emit-ir/--emit-asm，则仅输出显式选择的阶段\n"
+     << "  - 默认输出 IR\n"
+     << "  - 若使用 --emit-parse-tree/--emit-ir/--emit-asm，则仅输出显式选择的阶段\n"
      << "  - 可使用重定向写入文件:\n"
      << "      compiler --emit-asm test/test_case/simple_add.sy > out.s\n";
 }