IL代码，

.assembly extern mscorlib {}
 
 .assembly Test
 {
     .ver 1:0:1:0
 }
 .module test.exe
  
 .method static void main() cil managed
 {
     .maxstack 8
     .entrypoint
     .locals init (int32, int32)
   
     ldc.i4 4
     stloc.0        //Upper    limit of the Loop, total 5 
     ldc.i4 0 
     stloc.1        //Initialize the Starting of loop 

Start:     
     //Check if the Counter exceeds
     ldloc.1 
     ldloc.0 
     bgt Exit //If Second variable exceeds the first variable, then exit

     ldloc.1
     call void [mscorlib]System.Console::WriteLine(int32)

     //Increase the Counter
     ldc.i4 1
     ldloc.1
     add
     stloc.1
     br Start
Exit:    
     ret
}

构建运行如下；

 我还不是太理解，循环的开始和结束值是不是装入栈；循环变量加1也是在栈上操作；循环中啥也没干，只是输出了循环变量值；bgt、br是跳转语句；有时间继续；