C#指標未解決問題

考慮以下代碼：

C# code

unsafe            {                byte b = 3;                double d = 10.0;                int i = 5;                byte* pb = &b;                double* pd = &d;                int* pi = &i;                Console.WriteLine("Address of b is 0x{0:X},size is {1},value is {2}", (uint)pb, sizeof(byte), b);                Console.WriteLine("Address of d is 0x{0:X},size is {1},value is {2}", (uint)pd, sizeof(double), d);                Console.WriteLine("Address of i is 0x{0:X},size is {1},value is {2}", (uint)pi, sizeof(int), i);                Console.WriteLine("Address of pb is 0x{0:X},size is {1},value is 0x{2:X}", (uint)&pb, sizeof(byte*), (uint)pb);                Console.WriteLine("Address of pd is 0x{0:X},size is {1},value is 0x{2:X}", (uint)&pd, sizeof(double*), (uint)pd);                Console.WriteLine("Address of pi is 0x{0:X},size is {1},value is 0x{2:X}", (uint)&pi, sizeof(int*), (uint)pi);            }

在我機子上顯示的輸出結果是
Address of b is 0x12F46C,size is 1,value is 3
Address of d is 0x12F464,size is 8,value is 10
Address of i is 0x12F460,size is 4,value is 5
Address of pb is 0x12F45C,size is 4,value is 0x12F46C
Address of pd is 0x12F458,size is 4,value is 0x12F464
Address of pi is 0x12F454,size is 4,value is 0x12F460

現在我的問題是：看代碼，堆棧應該是從高地址向低地址向下填充，byte只佔1個位元組，而32位處理器系統堆棧的記憶體塊總是按照4位元組的倍數進行分配的。b的地址是0x12F46C，那麼b這個值應該儲存在0x12F468~0x12F46B中，佔4個位元組，然後為d分配記憶體，double類型佔8個個位元組，其地址應該是0x12F468,d應該儲存在0x12F460~0x12F467中，但為什麼輸出結果b佔了8個位元組的記憶體而d卻只佔了4個位元組的記憶體呢。
另外如果把代碼的最後三行去掉，即變成

C# code

unsafe            {                byte b = 3;                double d = 10.0;                int i = 5;                byte* pb = &b;                double* pd = &d;                int* pi = &i;                Console.WriteLine("Address of b is 0x{0:X},size is {1},value is {2}", (uint)pb, sizeof(byte), b);                Console.WriteLine("Address of d is 0x{0:X},size is {1},value is {2}", (uint)pd, sizeof(double), d);                Console.WriteLine("Address of i is 0x{0:X},size is {1},value is {2}", (uint)pi, sizeof(int), i);}

輸出結果為
Address of b is 0x12F45C,size is 1,value is 3
Address of d is 0x12F460,size is 8,value is 10
Address of i is 0x12F468,size is 4,value is 5
記憶體配置變成了從低地址到高地址向上填充，但此時b佔了4個位元組，d佔了8個位元組，何解？