--- a/clang/lib/Parse/ParseCbC.cpp	Wed Mar 11 19:23:03 2020 +0900
+++ b/clang/lib/Parse/ParseCbC.cpp	Wed Mar 11 19:59:35 2020 +0900
@@ -75,6 +75,37 @@
   };
 }
 
+/// goto with environment with out logjmp
+/// basic idea is prepare struct containes pointer to return value variable and stack pointer
+/// 
+/// int main() {
+///    struct __CbC_return {
+///      int* i;
+///      void* sp;
+//       void* fp;
+///    } ret; 
+//     int i;
+///    if (0) {
+//  _CBC_RETURN: 
+//        %fp = ret.fp;
+//        %rsp = ret.sp;
+//        i = *(ret.i); //?
+//        return i;
+//     }
+///    ret.i = &i;
+///    ret.sp = %rsp;
+//     ret.fp = %rfp;
+///    __code c(int i,void* env) = _CBC_RETURN;
+///    goto f(c, &ret);
+/// }
+/// 
+/// __code ret(int, void* env) {
+//      sp = env;
+//      %rax = 1;
+//      jmp _CBC_RETURN;
+/// }
+/// 
+///
 
 /// Prepare__retForGotoWithTheEnvExpr - Prepare __CbC_return, code segment for returning and some necessary statements.
 /// It is called when the parser find __return and statements are put into complex statement.