每个变量初始化:
int x = 2;
将要求值在堆栈上:(堆栈大小:到目前为止需要 1 个)
.locals init ([0] int32 x,
[1] int32 y,
[2] int32 a,
[3] int32 b,
[4] int32 c)
IL_0000: ldc.i4.2 // push 2 to the stack
IL_0001: stloc.0 // load local variable 0 from stack ( x = 2 )
这些操作按顺序发生,因此所需的最大堆栈大小仍为 1,期间:
int y = 3;
int a = 4;
int b = 5;
int c = 6;
当涉及到这一点时:
Console.WriteLine(x + y + a + b + c);
要添加任意两个变量,需要堆栈大小为 2:
IL_000b: ldloc.0 // copy to stack x, max stack size required is still 1.
IL_000c: ldloc.1 // copy to stack y, max stack size required is 2 now.
IL_000d: add // execute add, will cause the sum x + y to be on stack
IL_000e: ldloc.2 // copy to stack a
IL_000f: add // execute add... (adds a to the result of x + y)
....
取消注释 Add 方法时的差异 IL 如下。
调用方法时,您需要将实例引用压入堆栈(这意味着,如果 Add 方法是非静态的,则应将指向其声明类型的实例指针压入堆栈)
然后,每个需要传递给方法的参数也应该被压入堆栈。
因此,在您的情况下,Add 方法的参数数量定义了最大堆栈大小。向这个 Add 方法添加一个参数,您会看到最大堆栈大小将增加到 5:
// method is static so no need to push an instance pointer to the stack
IL_001a: ldc.i4.s 10 // push to stack
IL_001c: ldc.i4.s 20 // push to stack
IL_001e: ldc.i4.s 30 // push to stack
IL_0020: ldc.i4.s 40 // push to stack
IL_0022: call int32 Program::Add(int32,
int32,
int32,
int32)
IL_0027: call void [mscorlib]System.Console::WriteLine(int32)