ComputeBuffer data array improperly pinned

[odomobo]

For the ComputeBuffer constructor which takes a T[] data parameter, the array is pinned only for the duration of the call to clCreateBuffer. This appears to be fine if using CopyHostPointer, but is a bug when using UseHostPointer. This is because there's no guarantee that the array won't be moved by GC. Note that a fix to this will also handle the case that's given in the remark, about immediate parameters not working.

Steps to reproduce incorrect behavior:

1. Create some temporary objects on the small object heap.
2. Create some smallish arrays (< 85k bytes, so they go on the small object heap, so they will be candidates for compaction).
3. Create compute buffers from these arrays, using the flag UseHostPointer.
4. Create a lot of temporary objects on the small object heap, enough to cause a GC and compaction. The compaction will move your buffer arrays.
5. Execute a kernel, and observe that the data isn't correct.

[clSharp]

You are totally right, @odomobo. However, as I am not using Cloo anymore I do not have the time to fix this bug. If anyone submits a pull request fixing this bug I will be happy to merge it.

[firatsarlar]

If anyone could point me to a direction I would love to help.
First thing may a reproduceable code for the issue ,
I may find my way by debugging but still I have no idea about codebase.

[clSharp]

Writing code reproducing this issue is not easy. You would have to reliably force the garbage collector to move the buffer used in memory.

However, I do not think this is necessary. It is not to complicated to make sure the GCHandle is not freed before the buffer is disposed when the UseHostPointer flag is set.

[firatsarlar]

It would be nice to have test/s ( about issue ) to make sure everything work properly.

[clSharp]

Certainly this would be nice, but I am not aware of any way to check if an array is pinned from code. Perhaps there is one. Also I do not know how to reliably force the underlying memory of an array to be moved.