fix(ir): 修改了一下context的管理

src/ir/Context.cpp

@@ -7,11 +7,6 @@
 
 namespace ir {
 
-Context& DefaultContext() {
-  static Context ctx;
-  return ctx;
-}
-
 Context::~Context() = default;
 
 const std::shared_ptr<Type>& Context::Void() {
@@ -39,7 +34,7 @@ ConstantInt* Context::GetConstInt(int v) {
   auto it = const_ints_.find(v);
   if (it != const_ints_.end()) return it->second.get();
   auto inserted =
-      const_ints_.emplace(v, std::make_unique<ConstantInt>(v)).first;
+      const_ints_.emplace(v, std::make_unique<ConstantInt>(Int32(), v)).first;
   return inserted->second.get();
 }