[browser][coreCLR] Fix IL trimming in publish

[pavelsavara]

    <EnableAggressiveTrimming>true</EnableAggressiveTrimming>
    <PublishTrimmed>true</PublishTrimmed>

ThreadPool.BackgroundJobHandler failed
    at System.Environment.<FailFast>g____PInvoke|11_0(System.Runtime.CompilerServices.StackCrawlMarkHandle, UInt16*, System.Runtime.CompilerServices.ObjectHandleOnStack, UInt16*)
    at System.Environment.FailFast(System.Runtime.CompilerServices.StackCrawlMarkHandle, System.String, System.Runtime.CompilerServices.ObjectHandleOnStack, System.String)
    at System.Environment.FailFast(System.Threading.StackCrawlMark ByRef, System.String, System.Exception, System.String)
    at System.Environment.FailFast(System.String, System.Exception)
    at System.Threading.ThreadPool.BackgroundJobHandler()
 System.NotSupportedException: Linked away
    at System.Threading.Thread.ResetThreadPoolThread()
    at System.Threading.ThreadPoolWorkQueue.Dispatch()

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
See info in area-owners.md if you want to be subscribed.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/illink
See info in area-owners.md if you want to be subscribed.

[agocke]

EnableAggressiveTrimming

AFAIK this has no effect on ILLink.

[MichalStrehovsky]

Not sure if I'm reading the stack right, but if this is because the method body of ResetThreadPoolThread was rewritten to the throw (can be checked with ILDASM), the problem is that the VM is creating new instances of the Thread class through runtime magic (

runtime/src/coreclr/vm/threads.cpp

Line 3076 in 41558e7

THREADBASEREF attempt = (THREADBASEREF) AllocateObject(g_pThreadClass);

) and ILLink doesn't see a call to a constructor. I assume other platforms end up needing a constructor for other reasons. The fix would be to make sure some constructor on Thread is kept.

[jkotas]

The fix would be to make sure some constructor on Thread is kept.

We have been fixing these sort of issues by either calling the proper constructor from the VM; or by rooting the constructor in src\coreclr\vm\corelib.h (look for all constructors under #ifdef FOR_ILLINK)

[pavelsavara]

if this is because the method body of ResetThreadPoolThread was rewritten to the throw (can be checked with ILDASM)

Yes, it's Linked away in ILDASM

constructors under #ifdef FOR_ILLINK)

This helped locally, testing on CI now. Thanks!