unity crash in IL2CPP RELEASE scriptping backend

Hello everyone!
Maybe my technical level is not enough, this question makes me very difficult to understand！
I have a program that can write Buffer,this is the code

Code (CSharp):

1.  
2. public class WriteBuffer
3. {
4.     private byte[] beginPtr;
5.  
6.     private int position;
7.  
8.     private int length;
9.  
10.     public WriteBuffer(int len)
11.     {
12.         beginPtr = new byte[len];
13.         position = 0;
14.         length = 0;
15.         if (beginPtr != null)
16.         {
17.             length = len;
18.         }
19.     }
20.  
21.     public PbError.ErrorType writeUInt8(byte src)
22.     {
23.         if (beginPtr == null)
24.         {
25.             return PbError.ErrorType.PB_ERR_ARG_IS_NULL;
26.         }
27.  
28.         if (1 > length - position)
29.         {
30.             return PbError.ErrorType.PB_ERR_WRITE_BUFF_INSUFFIX;
31.         }
32.  
33.         beginPtr[position++] = src;
34.         return PbError.ErrorType.PB_NO_ERROR;
35.     }
36.  
37.     public PbError.ErrorType writeInt32(int src)
38.     {
39.         if (beginPtr == null)
40.         {
41.             return PbError.ErrorType.PB_ERR_ARG_IS_NULL;
42.         }
43.  
44.         if (4 > length - position)
45.         {
46.             return PbError.ErrorType.PB_ERR_WRITE_BUFF_INSUFFIX;
47.         }
48.  
49.         if (BitConverter.IsLittleEndian)
50.         {
51.             src = IPAddress.HostToNetworkOrder(src);
52.         }
53.  
54.         WriteBytes(src, beginPtr, ref position);
55.         return PbError.ErrorType.PB_NO_ERROR;
56.     }
57.  
58.     public PbError.ErrorType writeInt64(long src)
59.     {
60.         if (beginPtr == null)
61.         {
62.             return PbError.ErrorType.PB_ERR_ARG_IS_NULL;
63.         }
64.  
65.         if (8 > length - position)
66.         {
67.             return PbError.ErrorType.PB_ERR_WRITE_BUFF_INSUFFIX;
68.         }
69.  
70.         if (BitConverter.IsLittleEndian)
71.         {
72.             src = IPAddress.HostToNetworkOrder(src);
73.         }
74.  
75.         WriteBytes(src, beginPtr, ref position);
76.         return PbError.ErrorType.PB_NO_ERROR;
77.     }
78.  
79.     public unsafe void WriteBytes(int val, byte[] dest, ref int offset)
80.     {
81.         if (dest == null)
82.         {
83.             throw new ArgumentNullException("dest");
84.         }
85.  
86.         if (offset < 0 || offset + 4 > dest.Length)
87.         {
88.             throw new ArgumentNullException("offset");
89.         }
90.  
91.         fixed (byte* ptr = dest)
92.         {
93.             *(int*)(ptr + offset) = val;
94.         }
95.  
96.         offset += 4;
97.     }
98.  
99.     public unsafe void WriteBytes(long val, byte[] dest, ref int offset)
100.     {
101.         if (dest == null)
102.         {
103.             throw new ArgumentNullException("dest");
104.         }
105.  
106.         if (offset < 0 || offset + 8 > dest.Length)
107.         {
108.             throw new ArgumentNullException("offset");
109.         }
110.  
111.         fixed (byte* ptr = dest)
112.         {
113.             *(long*)(ptr + offset) = val;
114.         }
115.  
116.         offset += 8;
117.     }
118. }
119.  

and a test code here:write byte value first

Code (CSharp):

1.  
2. public class Main : MonoBehaviour
3. {
4.     private byte byte1;
5.     private long long1;
6.     private int int1;
7.  
8.     private const string LOG_FILTER_TAG = "SELF_LOG: ";
9.     WriteBuffer writeBuf = new WriteBuffer(1024);
10.  
11.     private void Start()
12.     {
13.         byte1 = 1;
14.         long1 = 10L;
15.         int1 = 100;
16.     }
17.  
18.     private void OnGUI()
19.     {
20.         if (GUILayout.Button("Write To Buffer", GUILayout.Height(100f), GUILayout.Width(200f)))
21.         {
22.             //write byte
23.             var ret = writeBuf.writeUInt8(byte1);
24.             Debug.Log(LOG_FILTER_TAG + (ret == PbError.ErrorType.PB_NO_ERROR ? "Byte Success" : ret.ToString()));
25.             //write long
26.             ret = writeBuf.writeInt64(long1);
27.             Debug.Log(LOG_FILTER_TAG + (ret == PbError.ErrorType.PB_NO_ERROR ? "long Success" : ret.ToString()));
28.             //write int
29.             ret = writeBuf.writeInt32(int1);
30.             Debug.Log(LOG_FILTER_TAG + (ret == PbError.ErrorType.PB_NO_ERROR ? "int Success" : ret.ToString()));
31.  
32.         }
33.     }
34. }
35.  
36.  

I made an Android apk which scripting backend is IL2CPP RELEASE and ran it .The crash happened when I executed the code in OnGUI.The log found this content：signal 7 (SIGBUS), code 1 (BUS_ADRALN) ！This means there is a problem with the memory alignment，Then I used libil2cpp.sym.so to locate the problem in the line of code

Code (CSharp):

1.  *(long*)(ptr + position) = val;

I guess this may be because I first wrote a byte, and then wrote a long at the Offset + ptr, but the address of this position is not a multiple of 8, so it crashed.
Then I changed my code:write long value first

Code (CSharp):

1.    
2.     private void OnGUI()
3.     {
4.         if (GUILayout.Button("Write To Buffer", GUILayout.Height(100f), GUILayout.Width(200f)))
5.         {
6.            
7.             //write long
8.            var ret = writeBuf.writeInt64(long1);
9.             Debug.Log(LOG_FILTER_TAG + (ret == PbError.ErrorType.PB_NO_ERROR ? "long Success" : ret.ToString()));
10.             //write byte
11.             ret = writeBuf.writeUInt8(byte1);
12.             Debug.Log(LOG_FILTER_TAG + (ret == PbError.ErrorType.PB_NO_ERROR ? "Byte Success" : ret.ToString()));
13.             //write int
14.             ret = writeBuf.writeInt32(int1);
15.             Debug.Log(LOG_FILTER_TAG + (ret == PbError.ErrorType.PB_NO_ERROR ? "int Success" : ret.ToString()));
16.  
17.         }
18.     }
19.  

Just such a change does not crash anymore.This is also something that makes me very confused,Why won't it crash this time.After writing byte, write int again. At this time, offset+ptr is definitely not a multiple of 4, but why doesn't it crash anymore?Did I understand something wrong?
By the way, the crash is only issued in IL2CPP RELEASE,IL2CPP DEBUG or Mono will not.

 

No one replied to me