GCHandle.Alloc(x, GCHandleType.Pinned) calls should be replaced by fixed statements with IntPtr casts where appropriate

[Mrnikbobjeff]

GCHandle.Alloc for pinned statements is strictly worse than using a fixed statement with a T* cast. The roslyn lowering does not incur the same penalty as the GCHandle. I was told to ping @jonathanpeppers for the performance topic

[Mrnikbobjeff]

After further sighting of the code I believe this would also reduce risks due to automatic unpinning in exception cases due to the finally lowering

[jonathanpeppers]

Can you link to the code you are suggesting to change here? We have no idea what might be using GCHandle without searching for it.

I know GCHandle is used internally by Objective-C bindings.