refactor(irgen): 完善irgen代码和文档，提升扩展兼容性

src/irgen/IRGenDecl.cpp

@@ -6,7 +6,18 @@
 #include "ir/IR.h"
 #include "utils/Log.h"
 
-void IRGenImpl::GenBlock(SysYParser::BlockContext& block) {
+namespace {
+
+std::string GetLValueName(SysYParser::LValueContext& lvalue) {
+  if (!lvalue.ID()) {
+    throw std::runtime_error(FormatError("irgen", "非法左值"));
+  }
+  return lvalue.ID()->getText();
+}
+
+}  // namespace
+
+void IRGenImpl::GenBlock(SysYParser::BlockStmtContext& block) {
   for (auto* item : block.blockItem()) {
     if (item) {
       if (GenBlockItem(*item)) {
@@ -29,14 +40,21 @@ bool IRGenImpl::GenBlockItem(SysYParser::BlockItemContext& item) {
 }
 
 void IRGenImpl::GenDecl(SysYParser::DeclContext& decl) {
-  if (decl.varDecl()) {
-    GenVarDecl(*decl.varDecl());
-    return;
+  if (!decl.btype() || !decl.btype()->INT()) {
+    throw std::runtime_error(FormatError("irgen", "当前仅支持局部 int 变量声明"));
   }
-  throw std::runtime_error(FormatError("irgen", "暂不支持的声明类型"));
+  auto* var_def = decl.varDef();
+  if (!var_def) {
+    throw std::runtime_error(FormatError("irgen", "非法变量声明"));
+  }
+  GenVarDef(*var_def);
 }
 
-void IRGenImpl::GenVarDecl(SysYParser::VarDeclContext& decl) {
+void IRGenImpl::GenVarDef(SysYParser::VarDefContext& decl) {
+  if (!decl.lValue()) {
+    throw std::runtime_error(FormatError("irgen", "变量声明缺少名称"));
+  }
+  GetLValueName(*decl.lValue());
   if (storage_map_.find(&decl) != storage_map_.end()) {
     throw std::runtime_error(FormatError("irgen", "声明重复生成存储槽位"));
   }
@@ -44,8 +62,11 @@ void IRGenImpl::GenVarDecl(SysYParser::VarDeclContext& decl) {
   storage_map_[&decl] = slot;
 
   ir::Value* init = nullptr;
-  if (decl.exp()) {
-    init = GenExpr(*decl.exp());
+  if (auto* init_value = decl.initValue()) {
+    if (!init_value->exp()) {
+      throw std::runtime_error(FormatError("irgen", "当前不支持聚合初始化"));
+    }
+    init = GenExpr(*init_value->exp());
   } else {
     init = builder_.CreateConstInt(0);
   }

src/irgen/IRGenExp.cpp

@@ -7,49 +7,38 @@
 #include "utils/Log.h"
 
 ir::Value* IRGenImpl::GenExpr(SysYParser::ExpContext& expr) {
-  if (!expr.addExp()) {
-    throw std::runtime_error(FormatError("irgen", "非法表达式"));
+  if (auto* paren = dynamic_cast<SysYParser::ParenExpContext*>(&expr)) {
+    return GenExpr(*paren->exp());
   }
-  return GenAddExpr(*expr.addExp());
-}
-
-ir::Value* IRGenImpl::GenAddExpr(SysYParser::AddExpContext& add) {
-  // 当前表达式层次仍是最小实现，直接贴合 addExp -> primary 的语法形状。
-  const auto& terms = add.primary();
-  if (terms.empty()) {
-    throw std::runtime_error(FormatError("irgen", "空加法表达式"));
+  if (auto* number = dynamic_cast<SysYParser::NumberExpContext*>(&expr)) {
+    if (!number->number() || !number->number()->ILITERAL()) {
+      throw std::runtime_error(FormatError("irgen", "当前仅支持整数字面量"));
+    }
+    return builder_.CreateConstInt(std::stoi(number->number()->getText()));
   }
-
-  ir::Value* acc = GenPrimary(*terms[0]);
-  for (size_t i = 1; i < terms.size(); ++i) {
-    ir::Value* rhs = GenPrimary(*terms[i]);
-    std::string name = module_.GetContext().NextTemp();
-    acc = builder_.CreateBinary(ir::Opcode::Add, acc, rhs, name);
-  }
-  return acc;
-}
-
-ir::Value* IRGenImpl::GenPrimary(SysYParser::PrimaryContext& primary) {
-  if (primary.Number()) {
-    return builder_.CreateConstInt(std::stoi(primary.Number()->getText()));
-  }
-  if (primary.Ident()) {
-    auto* decl = sema_.ResolveVarUse(&primary);
+  if (auto* var = dynamic_cast<SysYParser::VarExpContext*>(&expr)) {
+    if (!var->var() || !var->var()->ID()) {
+      throw std::runtime_error(FormatError("irgen", "当前仅支持普通整型变量"));
+    }
+    auto* decl = sema_.ResolveVarUse(var->var());
     if (!decl) {
       throw std::runtime_error(
           FormatError("irgen",
-                      "变量使用缺少语义绑定: " + primary.Ident()->getText()));
+                      "变量使用缺少语义绑定: " + var->var()->ID()->getText()));
     }
     auto it = storage_map_.find(decl);
     if (it == storage_map_.end()) {
       throw std::runtime_error(
           FormatError("irgen",
-                      "变量声明缺少存储槽位: " + primary.Ident()->getText()));
+                      "变量声明缺少存储槽位: " + var->var()->ID()->getText()));
     }
     return builder_.CreateLoad(it->second, module_.GetContext().NextTemp());
   }
-  if (primary.exp()) {
-    return GenExpr(*primary.exp());
+  if (auto* binary = dynamic_cast<SysYParser::AdditiveExpContext*>(&expr)) {
+    ir::Value* lhs = GenExpr(*binary->exp(0));
+    ir::Value* rhs = GenExpr(*binary->exp(1));
+    return builder_.CreateBinary(ir::Opcode::Add, lhs, rhs,
+                                 module_.GetContext().NextTemp());
   }
   throw std::runtime_error(FormatError("irgen", "暂不支持的表达式形式"));
 }

src/irgen/IRGenFunc.cpp

@@ -28,26 +28,31 @@ IRGenImpl::IRGenImpl(ir::Module& module, const SemanticContext& sema)
       builder_(module.GetContext(), nullptr) {}
 
 void IRGenImpl::Gen(SysYParser::CompUnitContext& cu) {
-  if (!cu.funcDef()) {
-    throw std::runtime_error(FormatError("irgen", "缺少 main 定义"));
+  auto* func = cu.funcDef();
+  if (func && func->ID() && func->ID()->getText() == "main") {
+    GenFuncDef(*func);
+    return;
   }
-  GenFuncDef(*cu.funcDef());
+  throw std::runtime_error(FormatError("irgen", "缺少 main 定义"));
 }
 
 void IRGenImpl::GenFuncDef(SysYParser::FuncDefContext& func) {
-  if (!func.block()) {
+  if (!func.blockStmt()) {
     throw std::runtime_error(FormatError("irgen", "函数体为空"));
   }
-  if (!func.Ident()) {
+  if (!func.ID()) {
     throw std::runtime_error(FormatError("irgen", "缺少函数名"));
   }
+  if (!func.funcType() || !func.funcType()->INT()) {
+    throw std::runtime_error(FormatError("irgen", "当前仅支持 int main"));
+  }
 
   func_ = module_.CreateFunction(
-      func.Ident()->getText(), module_.GetContext().Int32());
+      func.ID()->getText(), module_.GetContext().Int32());
   builder_.SetInsertPoint(func_->GetEntry());
   storage_map_.clear();
 
-  GenBlock(*func.block());
+  GenBlock(*func.blockStmt());
   // 语义正确性主要由 sema 保证，这里只兜底检查 IR 结构是否合法。
   VerifyFunctionStructure(*func_);
 }

src/sem/SymbolTable.cpp

@@ -3,7 +3,7 @@
 #include "sem/SymbolTable.h"
 
 void SymbolTable::Add(const std::string& name,
-                      SysYParser::VarDeclContext* decl) {
+                      SysYParser::VarDefContext* decl) {
   table_[name] = decl;
 }
 
@@ -11,7 +11,7 @@ bool SymbolTable::Contains(const std::string& name) const {
   return table_.find(name) != table_.end();
 }
 
-SysYParser::VarDeclContext* SymbolTable::Lookup(const std::string& name) const {
+SysYParser::VarDefContext* SymbolTable::Lookup(const std::string& name) const {
   auto it = table_.find(name);
   return it == table_.end() ? nullptr : it->second;
 }