Support dynamically creating tailored continuation layouts #120411

jakobbotsch · 2025-10-04T23:16:29Z

Add ability for the VM to dynamically create continuation layout types and for the JIT to request such types to be created.

dotnet-policy-service · 2025-10-04T23:17:32Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
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src/coreclr/vm/jitinterface.cpp

src/coreclr/vm/methodtable.h

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs

Now that we store directly into the ThunkTask's result we do not need to allocate a tail continuation at all.

src/coreclr/vm/jitinterface.cpp

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs

src/coreclr/vm/jitinterface.cpp

src/coreclr/vm/methodtable.cpp

…uation-layouts

src/coreclr/vm/methodtable.inl

See discussion around #120411 (comment).

jkotas · 2025-10-16T20:21:50Z

Test failures look related: System.InvalidProgramException: Invalid IL code in AwaitNotAsync:AsyncEntryPoint

jakobbotsch · 2025-10-16T20:55:14Z

Test failures look related: System.InvalidProgramException: Invalid IL code in AwaitNotAsync:AsyncEntryPoint

I think this one was just Mono complaining about not supporting runtime async. But the 32-bit coreclr failures were related. Pushed a fix for that one, and I need to remember to revert the enabling of the testing.

src/tests/async/Directory.Build.targets

jakobbotsch · 2025-10-16T21:01:36Z

I still need to do some final testing that verifies that the ETW events look right, but this should be ready for another look @jkotas @noahfalk @VSadov. Anything else you see here? I opened #120799 and #120800 for follow-up diagnostics work.

cc @dotnet/jit-contrib PTAL @AndyAyersMS. On the JIT side this is mostly simplifying things by removing the indirections through separate arrays stored in Continuation, and by no longer needing to store/access GC refs of locals separately.

jakobbotsch · 2025-10-16T21:12:40Z

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs

+        private static Task<T?> FinalizeTaskReturningThunk<T>()
        {
-            Continuation finalContinuation = new Continuation();
-
-            // Note that the exact location the return value is placed is tied
-            // into getAsyncResumptionStub in the VM, so do not change this
-            // without also changing that code (and the JIT).
-            if (RuntimeHelpers.IsReferenceOrContainsReferences<T>())
-            {
-                finalContinuation.Flags = CorInfoContinuationFlags.CORINFO_CONTINUATION_RESULT_IN_GCDATA | CorInfoContinuationFlags.CORINFO_CONTINUATION_NEEDS_EXCEPTION;
-                finalContinuation.GCData = new object[1];
-            }
-            else
-            {
-                finalContinuation.Flags = CorInfoContinuationFlags.CORINFO_CONTINUATION_NEEDS_EXCEPTION;
-                finalContinuation.Data = new byte[Unsafe.SizeOf<T>()];
-            }
-
-            continuation.Next = finalContinuation;
-


We now represent the tail with a null "next" continuation. The problem with that is figuring out where to put the result of the final continuation -- we now use the storage inside the RuntimeAsyncTask<T>.m_result as the place to put it when we get to the end.

...coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.CoreCLR.cs

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs

src/coreclr/inc/corinfo.h

src/coreclr/jit/async.cpp

src/coreclr/inc/corinfo.h

noahfalk

This looks good to me modulo making RuntimeAsync on by default. If there is a need to get it on by default regardless of the diagnostics I'd suggest we do it in a separate PR.

src/coreclr/inc/clrconfigvalues.h

AndyAyersMS

JIT changes look good.

jakobbotsch added 4 commits October 4, 2025 15:20

Initial

7d27090

Fix build, make tests run

6743534

Tailored continuation layouts

0f8cd9c

Add ability for the VM to dynamically create continuation layout types and for the JIT to request such types to be created.

Update type

a642f42

github-actions bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Oct 4, 2025

dotnet-policy-service bot assigned jakobbotsch Oct 4, 2025

jakobbotsch added 3 commits October 5, 2025 01:24

Fix bug

03a640d

Fix some bugs

a99ce96

Run thunk generator

fa1820a

jkotas reviewed Oct 5, 2025

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jkotas reviewed Oct 5, 2025

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jkoritzinsky reviewed Oct 5, 2025

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jakobbotsch added 4 commits October 6, 2025 15:59

Create a manager in the LoaderAllocator to hold map and create types

e4a75f1

Use SPC for continuation's module

82995d5

Remove unnecessary continuation allocation

38bdf11

Now that we store directly into the ThunkTask's result we do not need to allocate a tail continuation at all.

Fix some bugs

97de35e

jakobbotsch mentioned this pull request Oct 7, 2025

Add debug information for runtime async methods #120303

Open

jakobbotsch commented Oct 7, 2025

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jakobbotsch commented Oct 7, 2025

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jkotas reviewed Oct 7, 2025

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jkotas reviewed Oct 7, 2025

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jakobbotsch added 5 commits October 7, 2025 16:40

Fix type GC info, add debug name, remove comments

fb296e3

Refactor building of obj refs bitmap into helper class

a3e223f

Properly allocate space for KeepAlive object

71b47b0

Merge branch 'main' of github.com:dotnet/runtime into tailored-contin…

7df6464

…uation-layouts

Fix bitmap building for implicit byrefs

badee7d

jakobbotsch commented Oct 7, 2025

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Run jit-format, remove copilot comment

56c403a

davidwrighton requested a review from noahfalk October 7, 2025 23:22

Fix non Windows build

98917c0

build-analysis bot mentioned this pull request Oct 15, 2025

Test failure: System.IO.Tests.FileInfo_SymbolicLinks.ResolveLinkTarget_Succeeds #120380

Open

This was referenced Oct 16, 2025

Raise profiler ClassLoad events for array method tables #120796

Merged

Follow-up diagnostics work for dynamic metadata-less types in .NET 11 #120800

Open

Fix OFFSETOF__CORINFO_Continuation__data for 32 bit

ec99d53

jkotas pushed a commit that referenced this pull request Oct 16, 2025

Raise profiler ClassLoad events for array method tables (#120796)

2a63651

See discussion around #120411 (comment).

Remove CORINFO_CONTINUATION_DATA_OFFSETS; implement SuperPMI support

9b3eea9

jakobbotsch added 2 commits October 16, 2025 22:28

Sort all object refs to be first

21698ea

Pass keep alive offset as an argument to complex allocation helpers

69f8eb6

jakobbotsch commented Oct 16, 2025

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jakobbotsch requested a review from AndyAyersMS October 16, 2025 21:01

jakobbotsch mentioned this pull request Oct 16, 2025

Support moving continuations to SynchronizationContext/TaskScheduler #117314

Merged

jakobbotsch commented Oct 16, 2025

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