Cache continuation used for runtime async callable value task thunks

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

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[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
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17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
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18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
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18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
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18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
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19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
12,425,728	12,420,608	-5,120	-0.041%	✅	System.Xml.Linq.SDMSample.Tests.exe
21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
15,048,192	15,043,584	-4,608	-0.031%	✅	System.Data.DataSetExtensions.Tests.exe
16,673,280	16,668,160	-5,120	-0.031%	✅	System.Xml.Linq.Properties.Tests.exe
11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
17,123,840	17,118,720	-5,120	-0.030%	✅	System.Xml.Linq.TreeManipulation.Tests.exe
33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
18,381,312	18,376,704	-4,608	-0.025%	✅	Microsoft.Extensions.Primitives.Tests.exe
20,099,584	20,094,464	-5,120	-0.025%	✅	Microsoft.Extensions.Configuration.Json.Tests.exe
10,521,600	10,519,040	-2,560	-0.024%	✅	Microsoft.Extensions.Options.Tests.exe
16,973,824	16,977,920	+4,096	+0.024%	❌	System.Private.CoreLib.dll
20,038,656	20,034,048	-4,608	-0.023%	✅	Microsoft.Extensions.Configuration.UserSecrets.Tests.exe
19,972,096	19,967,488	-4,608	-0.023%	✅	Microsoft.Extensions.Logging.Tests.exe
9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
18,356,224	18,352,128	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Composite.Tests.exe
44,814,336	44,804,608	-9,728	-0.022%	✅	System.Runtime.Tests.exe
18,774,016	18,769,920	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Physical.Tests.exe
18,491,904	18,487,808	-4,096	-0.022%	✅	Microsoft.Extensions.Configuration.Tests.exe
9,346,560	9,344,512	-2,048	-0.022%	✅	Microsoft.Extensions.Diagnostics.Abstractions.Tests.exe
10,118,656	10,116,608	-2,048	-0.020%	✅	Microsoft.Extensions.Caching.Memory.Tests.exe
30,107,136	30,101,504	-5,632	-0.019%	✅	Microsoft.Extensions.DependencyModel.Tests.exe
10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
8,989,696	8,988,160	-1,536	-0.017%	✅	System.Net.Primitives.Pal.Tests.exe
33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
9,454,080	9,452,544	-1,536	-0.016%	✅	Microsoft.Extensions.Logging.Testing.Tests.exe
9,630,720	9,629,184	-1,536	-0.016%	✅	System.Composition.Convention.Tests.exe
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11,484,160	11,482,624	-1,536	-0.013%	✅	System.IO.Ports.Tests.exe
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9,083,392	9,082,880	-512	-0.006%	✅	System.ValueTuple.Tests.exe
8,606,208	8,605,696	-512	-0.006%	✅	System.Resources.Writer.Tests.exe
8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
8,863,232	8,862,720	-512	-0.006%	✅	System.Reflection.Extensions.Tests.exe
8,670,208	8,669,696	-512	-0.006%	✅	System.Runtime.Handles.Tests.exe
9,165,824	9,165,312	-512	-0.006%	✅	System.Globalization.Calendars.Tests.exe
8,543,744	8,543,232	-512	-0.006%	✅	System.IO.FileSystem.Primitives.Tests.exe
8,592,384	8,591,872	-512	-0.006%	✅	Microsoft.Bcl.Numerics.Tests.exe
8,952,832	8,952,320	-512	-0.006%	✅	Microsoft.Bcl.Memory.Tests.exe
8,717,312	8,716,800	-512	-0.006%	✅	System.Diagnostics.FileVersionInfo.Tests.exe
8,700,416	8,699,904	-512	-0.006%	✅	System.IO.FileSystem.Manual.Tests.exe
8,929,792	8,929,280	-512	-0.006%	✅	System.IO.Pipes.AccessControl.Tests.exe
8,624,128	8,623,616	-512	-0.006%	✅	System.Composition.Runtime.Tests.exe
9,108,992	9,108,480	-512	-0.006%	✅	System.IO.FileSystem.AccessControl.Tests.exe
8,559,104	8,558,592	-512	-0.006%	✅	System.Composition.AttributeModel.Tests.exe
8,759,296	8,758,784	-512	-0.006%	✅	Invariant.Tests.exe
8,547,840	8,547,328	-512	-0.006%	✅	System.ComponentModel.Tests.exe
9,161,728	9,161,216	-512	-0.006%	✅	System.ComponentModel.Primitives.Tests.exe
8,959,488	8,958,976	-512	-0.006%	✅	System.Threading.AccessControl.Tests.exe
8,991,232	8,990,720	-512	-0.006%	✅	Microsoft.Win32.Registry.Tests.exe
8,647,680	8,647,168	-512	-0.006%	✅	Microsoft.Win32.Registry.AccessControl.Tests.exe
8,549,376	8,548,864	-512	-0.006%	✅	System.Diagnostics.Tools.Tests.exe
8,664,576	8,664,064	-512	-0.006%	✅	Microsoft.Win32.Primitives.Tests.exe
9,750,016	9,749,504	-512	-0.005%	✅	System.Collections.Specialized.Tests.exe
22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
9,852,928	9,852,416	-512	-0.005%	✅	System.Formats.Nrbf.Tests.exe
9,763,328	9,762,816	-512	-0.005%	✅	System.Formats.Asn1.Tests.exe
9,361,408	9,360,896	-512	-0.005%	✅	System.Security.Permissions.Tests.exe
11,048,448	11,047,936	-512	-0.005%	✅	System.Runtime.Numerics.Tests.exe
9,627,136	9,626,624	-512	-0.005%	✅	System.Diagnostics.EventLog.Tests.exe
18,779,136	18,778,112	-1,024	-0.005%	✅	System.Numerics.Vectors.Tests.exe
9,746,432	9,745,920	-512	-0.005%	✅	System.Threading.RateLimiting.Tests.exe
9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
9,949,696	9,949,184	-512	-0.005%	✅	System.Collections.NonGeneric.Tests.exe
9,486,848	9,486,336	-512	-0.005%	✅	Microsoft.Extensions.Configuration.Ini.Tests.exe
13,553,664	13,554,176	+512	+0.004%	❌	crossgen2.exe
11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
11,381,248	11,380,736	-512	-0.004%	✅	System.Net.Security.Unit.Tests.exe
15,545,856	15,545,344	-512	-0.003%	✅	System.Linq.Tests.exe
17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

[dotnet-policy-service]

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

[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
18,947,584	18,936,832	-10,752	-0.057%	✅	System.Runtime.Caching.Tests.exe
17,168,896	17,159,168	-9,728	-0.057%	✅	System.Runtime.Serialization.Formatters.Disabled.Tests.exe
17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
17,223,168	17,213,952	-9,216	-0.054%	✅	System.Net.ServicePoint.Tests.exe
18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
17,363,968	17,354,752	-9,216	-0.053%	✅	Microsoft.Win32.SystemEvents.Tests.exe
17,306,112	17,296,896	-9,216	-0.053%	✅	System.Security.Claims.Tests.exe
18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
17,369,088	17,360,384	-8,704	-0.050%	✅	System.Diagnostics.StackTrace.Tests.exe
18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
19,876,864	19,867,136	-9,728	-0.049%	✅	System.Text.Encoding.Tests.exe
17,670,656	17,661,952	-8,704	-0.049%	✅	System.Buffers.Tests.exe
19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
12,425,728	12,420,608	-5,120	-0.041%	✅	System.Xml.Linq.SDMSample.Tests.exe
21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
15,048,192	15,043,584	-4,608	-0.031%	✅	System.Data.DataSetExtensions.Tests.exe
16,673,280	16,668,160	-5,120	-0.031%	✅	System.Xml.Linq.Properties.Tests.exe
11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
17,123,840	17,118,720	-5,120	-0.030%	✅	System.Xml.Linq.TreeManipulation.Tests.exe
33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
18,381,312	18,376,704	-4,608	-0.025%	✅	Microsoft.Extensions.Primitives.Tests.exe
20,099,584	20,094,464	-5,120	-0.025%	✅	Microsoft.Extensions.Configuration.Json.Tests.exe
10,521,600	10,519,040	-2,560	-0.024%	✅	Microsoft.Extensions.Options.Tests.exe
16,973,824	16,977,920	+4,096	+0.024%	❌	System.Private.CoreLib.dll
20,038,656	20,034,048	-4,608	-0.023%	✅	Microsoft.Extensions.Configuration.UserSecrets.Tests.exe
19,972,096	19,967,488	-4,608	-0.023%	✅	Microsoft.Extensions.Logging.Tests.exe
9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
18,356,224	18,352,128	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Composite.Tests.exe
44,814,336	44,804,608	-9,728	-0.022%	✅	System.Runtime.Tests.exe
18,774,016	18,769,920	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Physical.Tests.exe
18,491,904	18,487,808	-4,096	-0.022%	✅	Microsoft.Extensions.Configuration.Tests.exe
9,346,560	9,344,512	-2,048	-0.022%	✅	Microsoft.Extensions.Diagnostics.Abstractions.Tests.exe
10,118,656	10,116,608	-2,048	-0.020%	✅	Microsoft.Extensions.Caching.Memory.Tests.exe
30,107,136	30,101,504	-5,632	-0.019%	✅	Microsoft.Extensions.DependencyModel.Tests.exe
10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
8,989,696	8,988,160	-1,536	-0.017%	✅	System.Net.Primitives.Pal.Tests.exe
33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
9,454,080	9,452,544	-1,536	-0.016%	✅	Microsoft.Extensions.Logging.Testing.Tests.exe
9,630,720	9,629,184	-1,536	-0.016%	✅	System.Composition.Convention.Tests.exe
9,314,816	9,313,280	-1,536	-0.016%	✅	System.Net.Primitives.UnitTests.Tests.exe
11,484,160	11,482,624	-1,536	-0.013%	✅	System.IO.Ports.Tests.exe
8,601,600	8,600,576	-1,024	-0.012%	✅	Microsoft.Extensions.Hosting.Abstractions.Tests.exe
8,720,384	8,719,360	-1,024	-0.012%	✅	System.Private.Uri.Unit.Tests.exe
8,546,816	8,545,792	-1,024	-0.012%	✅	System.Runtime.CompilerServices.VisualC.Tests.exe
8,653,312	8,652,288	-1,024	-0.012%	✅	System.Globalization.CalendarsWithConfigSwitch.Tests.exe
8,836,608	8,835,584	-1,024	-0.012%	✅	System.Console.Manual.Tests.exe
9,364,480	9,363,456	-1,024	-0.011%	✅	System.Reflection.Context.Tests.exe
9,041,408	9,040,384	-1,024	-0.011%	✅	System.Net.NameResolution.Pal.Tests.exe
9,646,592	9,645,568	-1,024	-0.011%	✅	System.Private.Uri.Functional.Tests.exe
9,704,448	9,703,424	-1,024	-0.011%	✅	System.Text.RegularExpressions.Unit.Tests.exe
9,206,272	9,205,248	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.EnvironmentVariables.Tests.exe
9,004,032	9,003,008	-1,024	-0.011%	✅	System.Runtime.Serialization.Primitives.Tests.exe
9,056,256	9,055,232	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.CommandLine.Tests.exe
9,216,512	9,215,488	-1,024	-0.011%	✅	System.ServiceProcess.ServiceController.Tests.exe
9,539,584	9,538,560	-1,024	-0.011%	✅	System.IO.Hashing.Tests.exe
9,671,168	9,670,144	-1,024	-0.011%	✅	Microsoft.Extensions.Hosting.Functional.Tests.exe
4,940,288	4,939,776	-512	-0.010%	✅	coreclr.dll
10,935,808	10,934,784	-1,024	-0.009%	✅	System.Runtime.Intrinsics.Tests.exe
11,610,112	11,609,088	-1,024	-0.009%	✅	System.Resources.Extensions.Tests.exe
11,193,856	11,192,832	-1,024	-0.009%	✅	System.Text.Encodings.Web.Tests.exe
12,287,488	12,286,464	-1,024	-0.008%	✅	System.Net.NetworkInformation.Functional.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Nls.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Tests.exe
9,039,360	9,038,848	-512	-0.006%	✅	Microsoft.Extensions.FileSystemGlobbing.Tests.exe
8,558,080	8,557,568	-512	-0.006%	✅	System.Text.Encoding.Extensions.Tests.exe
8,704,512	8,704,000	-512	-0.006%	✅	System.Security.SecureString.Tests.exe
8,701,440	8,700,928	-512	-0.006%	✅	System.Security.Cryptography.ProtectedData.Tests.exe
8,688,128	8,687,616	-512	-0.006%	✅	System.Runtime.InteropServices.ComDisabled.Tests.exe
9,143,808	9,143,296	-512	-0.006%	✅	System.Security.AccessControl.Tests.exe
9,025,536	9,025,024	-512	-0.006%	✅	System.Reflection.TypeExtensions.Tests.exe
8,812,032	8,811,520	-512	-0.006%	✅	System.Resources.Reader.Tests.exe
9,083,392	9,082,880	-512	-0.006%	✅	System.ValueTuple.Tests.exe
8,606,208	8,605,696	-512	-0.006%	✅	System.Resources.Writer.Tests.exe
8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
8,863,232	8,862,720	-512	-0.006%	✅	System.Reflection.Extensions.Tests.exe
8,670,208	8,669,696	-512	-0.006%	✅	System.Runtime.Handles.Tests.exe
9,165,824	9,165,312	-512	-0.006%	✅	System.Globalization.Calendars.Tests.exe
8,543,744	8,543,232	-512	-0.006%	✅	System.IO.FileSystem.Primitives.Tests.exe
8,592,384	8,591,872	-512	-0.006%	✅	Microsoft.Bcl.Numerics.Tests.exe
8,952,832	8,952,320	-512	-0.006%	✅	Microsoft.Bcl.Memory.Tests.exe
8,717,312	8,716,800	-512	-0.006%	✅	System.Diagnostics.FileVersionInfo.Tests.exe
8,700,416	8,699,904	-512	-0.006%	✅	System.IO.FileSystem.Manual.Tests.exe
8,929,792	8,929,280	-512	-0.006%	✅	System.IO.Pipes.AccessControl.Tests.exe
8,624,128	8,623,616	-512	-0.006%	✅	System.Composition.Runtime.Tests.exe
9,108,992	9,108,480	-512	-0.006%	✅	System.IO.FileSystem.AccessControl.Tests.exe
8,559,104	8,558,592	-512	-0.006%	✅	System.Composition.AttributeModel.Tests.exe
8,759,296	8,758,784	-512	-0.006%	✅	Invariant.Tests.exe
8,547,840	8,547,328	-512	-0.006%	✅	System.ComponentModel.Tests.exe
9,161,728	9,161,216	-512	-0.006%	✅	System.ComponentModel.Primitives.Tests.exe
8,959,488	8,958,976	-512	-0.006%	✅	System.Threading.AccessControl.Tests.exe
8,991,232	8,990,720	-512	-0.006%	✅	Microsoft.Win32.Registry.Tests.exe
8,647,680	8,647,168	-512	-0.006%	✅	Microsoft.Win32.Registry.AccessControl.Tests.exe
8,549,376	8,548,864	-512	-0.006%	✅	System.Diagnostics.Tools.Tests.exe
8,664,576	8,664,064	-512	-0.006%	✅	Microsoft.Win32.Primitives.Tests.exe
9,750,016	9,749,504	-512	-0.005%	✅	System.Collections.Specialized.Tests.exe
22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
9,852,928	9,852,416	-512	-0.005%	✅	System.Formats.Nrbf.Tests.exe
9,763,328	9,762,816	-512	-0.005%	✅	System.Formats.Asn1.Tests.exe
9,361,408	9,360,896	-512	-0.005%	✅	System.Security.Permissions.Tests.exe
11,048,448	11,047,936	-512	-0.005%	✅	System.Runtime.Numerics.Tests.exe
9,627,136	9,626,624	-512	-0.005%	✅	System.Diagnostics.EventLog.Tests.exe
18,779,136	18,778,112	-1,024	-0.005%	✅	System.Numerics.Vectors.Tests.exe
9,746,432	9,745,920	-512	-0.005%	✅	System.Threading.RateLimiting.Tests.exe
9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
9,949,696	9,949,184	-512	-0.005%	✅	System.Collections.NonGeneric.Tests.exe
9,486,848	9,486,336	-512	-0.005%	✅	Microsoft.Extensions.Configuration.Ini.Tests.exe
13,553,664	13,554,176	+512	+0.004%	❌	crossgen2.exe
11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
11,381,248	11,380,736	-512	-0.004%	✅	System.Net.Security.Unit.Tests.exe
15,545,856	15,545,344	-512	-0.003%	✅	System.Linq.Tests.exe
17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

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Tagging subscribers to this area: @agocke
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[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
18,947,584	18,936,832	-10,752	-0.057%	✅	System.Runtime.Caching.Tests.exe
17,168,896	17,159,168	-9,728	-0.057%	✅	System.Runtime.Serialization.Formatters.Disabled.Tests.exe
17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
17,223,168	17,213,952	-9,216	-0.054%	✅	System.Net.ServicePoint.Tests.exe
18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
17,363,968	17,354,752	-9,216	-0.053%	✅	Microsoft.Win32.SystemEvents.Tests.exe
17,306,112	17,296,896	-9,216	-0.053%	✅	System.Security.Claims.Tests.exe
18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
17,369,088	17,360,384	-8,704	-0.050%	✅	System.Diagnostics.StackTrace.Tests.exe
18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
19,876,864	19,867,136	-9,728	-0.049%	✅	System.Text.Encoding.Tests.exe
17,670,656	17,661,952	-8,704	-0.049%	✅	System.Buffers.Tests.exe
19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
12,425,728	12,420,608	-5,120	-0.041%	✅	System.Xml.Linq.SDMSample.Tests.exe
21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
15,048,192	15,043,584	-4,608	-0.031%	✅	System.Data.DataSetExtensions.Tests.exe
16,673,280	16,668,160	-5,120	-0.031%	✅	System.Xml.Linq.Properties.Tests.exe
11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
17,123,840	17,118,720	-5,120	-0.030%	✅	System.Xml.Linq.TreeManipulation.Tests.exe
33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
18,381,312	18,376,704	-4,608	-0.025%	✅	Microsoft.Extensions.Primitives.Tests.exe
20,099,584	20,094,464	-5,120	-0.025%	✅	Microsoft.Extensions.Configuration.Json.Tests.exe
10,521,600	10,519,040	-2,560	-0.024%	✅	Microsoft.Extensions.Options.Tests.exe
16,973,824	16,977,920	+4,096	+0.024%	❌	System.Private.CoreLib.dll
20,038,656	20,034,048	-4,608	-0.023%	✅	Microsoft.Extensions.Configuration.UserSecrets.Tests.exe
19,972,096	19,967,488	-4,608	-0.023%	✅	Microsoft.Extensions.Logging.Tests.exe
9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
18,356,224	18,352,128	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Composite.Tests.exe
44,814,336	44,804,608	-9,728	-0.022%	✅	System.Runtime.Tests.exe
18,774,016	18,769,920	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Physical.Tests.exe
18,491,904	18,487,808	-4,096	-0.022%	✅	Microsoft.Extensions.Configuration.Tests.exe
9,346,560	9,344,512	-2,048	-0.022%	✅	Microsoft.Extensions.Diagnostics.Abstractions.Tests.exe
10,118,656	10,116,608	-2,048	-0.020%	✅	Microsoft.Extensions.Caching.Memory.Tests.exe
30,107,136	30,101,504	-5,632	-0.019%	✅	Microsoft.Extensions.DependencyModel.Tests.exe
10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
8,989,696	8,988,160	-1,536	-0.017%	✅	System.Net.Primitives.Pal.Tests.exe
33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
9,454,080	9,452,544	-1,536	-0.016%	✅	Microsoft.Extensions.Logging.Testing.Tests.exe
9,630,720	9,629,184	-1,536	-0.016%	✅	System.Composition.Convention.Tests.exe
9,314,816	9,313,280	-1,536	-0.016%	✅	System.Net.Primitives.UnitTests.Tests.exe
11,484,160	11,482,624	-1,536	-0.013%	✅	System.IO.Ports.Tests.exe
8,601,600	8,600,576	-1,024	-0.012%	✅	Microsoft.Extensions.Hosting.Abstractions.Tests.exe
8,720,384	8,719,360	-1,024	-0.012%	✅	System.Private.Uri.Unit.Tests.exe
8,546,816	8,545,792	-1,024	-0.012%	✅	System.Runtime.CompilerServices.VisualC.Tests.exe
8,653,312	8,652,288	-1,024	-0.012%	✅	System.Globalization.CalendarsWithConfigSwitch.Tests.exe
8,836,608	8,835,584	-1,024	-0.012%	✅	System.Console.Manual.Tests.exe
9,364,480	9,363,456	-1,024	-0.011%	✅	System.Reflection.Context.Tests.exe
9,041,408	9,040,384	-1,024	-0.011%	✅	System.Net.NameResolution.Pal.Tests.exe
9,646,592	9,645,568	-1,024	-0.011%	✅	System.Private.Uri.Functional.Tests.exe
9,704,448	9,703,424	-1,024	-0.011%	✅	System.Text.RegularExpressions.Unit.Tests.exe
9,206,272	9,205,248	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.EnvironmentVariables.Tests.exe
9,004,032	9,003,008	-1,024	-0.011%	✅	System.Runtime.Serialization.Primitives.Tests.exe
9,056,256	9,055,232	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.CommandLine.Tests.exe
9,216,512	9,215,488	-1,024	-0.011%	✅	System.ServiceProcess.ServiceController.Tests.exe
9,539,584	9,538,560	-1,024	-0.011%	✅	System.IO.Hashing.Tests.exe
9,671,168	9,670,144	-1,024	-0.011%	✅	Microsoft.Extensions.Hosting.Functional.Tests.exe
4,940,288	4,939,776	-512	-0.010%	✅	coreclr.dll
10,935,808	10,934,784	-1,024	-0.009%	✅	System.Runtime.Intrinsics.Tests.exe
11,610,112	11,609,088	-1,024	-0.009%	✅	System.Resources.Extensions.Tests.exe
11,193,856	11,192,832	-1,024	-0.009%	✅	System.Text.Encodings.Web.Tests.exe
12,287,488	12,286,464	-1,024	-0.008%	✅	System.Net.NetworkInformation.Functional.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Nls.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Tests.exe
9,039,360	9,038,848	-512	-0.006%	✅	Microsoft.Extensions.FileSystemGlobbing.Tests.exe
8,558,080	8,557,568	-512	-0.006%	✅	System.Text.Encoding.Extensions.Tests.exe
8,704,512	8,704,000	-512	-0.006%	✅	System.Security.SecureString.Tests.exe
8,701,440	8,700,928	-512	-0.006%	✅	System.Security.Cryptography.ProtectedData.Tests.exe
8,688,128	8,687,616	-512	-0.006%	✅	System.Runtime.InteropServices.ComDisabled.Tests.exe
9,143,808	9,143,296	-512	-0.006%	✅	System.Security.AccessControl.Tests.exe
9,025,536	9,025,024	-512	-0.006%	✅	System.Reflection.TypeExtensions.Tests.exe
8,812,032	8,811,520	-512	-0.006%	✅	System.Resources.Reader.Tests.exe
9,083,392	9,082,880	-512	-0.006%	✅	System.ValueTuple.Tests.exe
8,606,208	8,605,696	-512	-0.006%	✅	System.Resources.Writer.Tests.exe
8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
8,863,232	8,862,720	-512	-0.006%	✅	System.Reflection.Extensions.Tests.exe
8,670,208	8,669,696	-512	-0.006%	✅	System.Runtime.Handles.Tests.exe
9,165,824	9,165,312	-512	-0.006%	✅	System.Globalization.Calendars.Tests.exe
8,543,744	8,543,232	-512	-0.006%	✅	System.IO.FileSystem.Primitives.Tests.exe
8,592,384	8,591,872	-512	-0.006%	✅	Microsoft.Bcl.Numerics.Tests.exe
8,952,832	8,952,320	-512	-0.006%	✅	Microsoft.Bcl.Memory.Tests.exe
8,717,312	8,716,800	-512	-0.006%	✅	System.Diagnostics.FileVersionInfo.Tests.exe
8,700,416	8,699,904	-512	-0.006%	✅	System.IO.FileSystem.Manual.Tests.exe
8,929,792	8,929,280	-512	-0.006%	✅	System.IO.Pipes.AccessControl.Tests.exe
8,624,128	8,623,616	-512	-0.006%	✅	System.Composition.Runtime.Tests.exe
9,108,992	9,108,480	-512	-0.006%	✅	System.IO.FileSystem.AccessControl.Tests.exe
8,559,104	8,558,592	-512	-0.006%	✅	System.Composition.AttributeModel.Tests.exe
8,759,296	8,758,784	-512	-0.006%	✅	Invariant.Tests.exe
8,547,840	8,547,328	-512	-0.006%	✅	System.ComponentModel.Tests.exe
9,161,728	9,161,216	-512	-0.006%	✅	System.ComponentModel.Primitives.Tests.exe
8,959,488	8,958,976	-512	-0.006%	✅	System.Threading.AccessControl.Tests.exe
8,991,232	8,990,720	-512	-0.006%	✅	Microsoft.Win32.Registry.Tests.exe
8,647,680	8,647,168	-512	-0.006%	✅	Microsoft.Win32.Registry.AccessControl.Tests.exe
8,549,376	8,548,864	-512	-0.006%	✅	System.Diagnostics.Tools.Tests.exe
8,664,576	8,664,064	-512	-0.006%	✅	Microsoft.Win32.Primitives.Tests.exe
9,750,016	9,749,504	-512	-0.005%	✅	System.Collections.Specialized.Tests.exe
22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
9,852,928	9,852,416	-512	-0.005%	✅	System.Formats.Nrbf.Tests.exe
9,763,328	9,762,816	-512	-0.005%	✅	System.Formats.Asn1.Tests.exe
9,361,408	9,360,896	-512	-0.005%	✅	System.Security.Permissions.Tests.exe
11,048,448	11,047,936	-512	-0.005%	✅	System.Runtime.Numerics.Tests.exe
9,627,136	9,626,624	-512	-0.005%	✅	System.Diagnostics.EventLog.Tests.exe
18,779,136	18,778,112	-1,024	-0.005%	✅	System.Numerics.Vectors.Tests.exe
9,746,432	9,745,920	-512	-0.005%	✅	System.Threading.RateLimiting.Tests.exe
9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
9,949,696	9,949,184	-512	-0.005%	✅	System.Collections.NonGeneric.Tests.exe
9,486,848	9,486,336	-512	-0.005%	✅	Microsoft.Extensions.Configuration.Ini.Tests.exe
13,553,664	13,554,176	+512	+0.004%	❌	crossgen2.exe
11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
11,381,248	11,380,736	-512	-0.004%	✅	System.Net.Security.Unit.Tests.exe
15,545,856	15,545,344	-512	-0.003%	✅	System.Linq.Tests.exe
17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

[dotnet-policy-service]

Tagging subscribers to this area: @agocke
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[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
18,947,584	18,936,832	-10,752	-0.057%	✅	System.Runtime.Caching.Tests.exe
17,168,896	17,159,168	-9,728	-0.057%	✅	System.Runtime.Serialization.Formatters.Disabled.Tests.exe
17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
17,223,168	17,213,952	-9,216	-0.054%	✅	System.Net.ServicePoint.Tests.exe
18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
17,363,968	17,354,752	-9,216	-0.053%	✅	Microsoft.Win32.SystemEvents.Tests.exe
17,306,112	17,296,896	-9,216	-0.053%	✅	System.Security.Claims.Tests.exe
18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
17,369,088	17,360,384	-8,704	-0.050%	✅	System.Diagnostics.StackTrace.Tests.exe
18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
19,876,864	19,867,136	-9,728	-0.049%	✅	System.Text.Encoding.Tests.exe
17,670,656	17,661,952	-8,704	-0.049%	✅	System.Buffers.Tests.exe
19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
12,425,728	12,420,608	-5,120	-0.041%	✅	System.Xml.Linq.SDMSample.Tests.exe
21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
15,048,192	15,043,584	-4,608	-0.031%	✅	System.Data.DataSetExtensions.Tests.exe
16,673,280	16,668,160	-5,120	-0.031%	✅	System.Xml.Linq.Properties.Tests.exe
11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
17,123,840	17,118,720	-5,120	-0.030%	✅	System.Xml.Linq.TreeManipulation.Tests.exe
33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
18,381,312	18,376,704	-4,608	-0.025%	✅	Microsoft.Extensions.Primitives.Tests.exe
20,099,584	20,094,464	-5,120	-0.025%	✅	Microsoft.Extensions.Configuration.Json.Tests.exe
10,521,600	10,519,040	-2,560	-0.024%	✅	Microsoft.Extensions.Options.Tests.exe
16,973,824	16,977,920	+4,096	+0.024%	❌	System.Private.CoreLib.dll
20,038,656	20,034,048	-4,608	-0.023%	✅	Microsoft.Extensions.Configuration.UserSecrets.Tests.exe
19,972,096	19,967,488	-4,608	-0.023%	✅	Microsoft.Extensions.Logging.Tests.exe
9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
18,356,224	18,352,128	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Composite.Tests.exe
44,814,336	44,804,608	-9,728	-0.022%	✅	System.Runtime.Tests.exe
18,774,016	18,769,920	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Physical.Tests.exe
18,491,904	18,487,808	-4,096	-0.022%	✅	Microsoft.Extensions.Configuration.Tests.exe
9,346,560	9,344,512	-2,048	-0.022%	✅	Microsoft.Extensions.Diagnostics.Abstractions.Tests.exe
10,118,656	10,116,608	-2,048	-0.020%	✅	Microsoft.Extensions.Caching.Memory.Tests.exe
30,107,136	30,101,504	-5,632	-0.019%	✅	Microsoft.Extensions.DependencyModel.Tests.exe
10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
8,989,696	8,988,160	-1,536	-0.017%	✅	System.Net.Primitives.Pal.Tests.exe
33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
9,454,080	9,452,544	-1,536	-0.016%	✅	Microsoft.Extensions.Logging.Testing.Tests.exe
9,630,720	9,629,184	-1,536	-0.016%	✅	System.Composition.Convention.Tests.exe
9,314,816	9,313,280	-1,536	-0.016%	✅	System.Net.Primitives.UnitTests.Tests.exe
11,484,160	11,482,624	-1,536	-0.013%	✅	System.IO.Ports.Tests.exe
8,601,600	8,600,576	-1,024	-0.012%	✅	Microsoft.Extensions.Hosting.Abstractions.Tests.exe
8,720,384	8,719,360	-1,024	-0.012%	✅	System.Private.Uri.Unit.Tests.exe
8,546,816	8,545,792	-1,024	-0.012%	✅	System.Runtime.CompilerServices.VisualC.Tests.exe
8,653,312	8,652,288	-1,024	-0.012%	✅	System.Globalization.CalendarsWithConfigSwitch.Tests.exe
8,836,608	8,835,584	-1,024	-0.012%	✅	System.Console.Manual.Tests.exe
9,364,480	9,363,456	-1,024	-0.011%	✅	System.Reflection.Context.Tests.exe
9,041,408	9,040,384	-1,024	-0.011%	✅	System.Net.NameResolution.Pal.Tests.exe
9,646,592	9,645,568	-1,024	-0.011%	✅	System.Private.Uri.Functional.Tests.exe
9,704,448	9,703,424	-1,024	-0.011%	✅	System.Text.RegularExpressions.Unit.Tests.exe
9,206,272	9,205,248	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.EnvironmentVariables.Tests.exe
9,004,032	9,003,008	-1,024	-0.011%	✅	System.Runtime.Serialization.Primitives.Tests.exe
9,056,256	9,055,232	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.CommandLine.Tests.exe
9,216,512	9,215,488	-1,024	-0.011%	✅	System.ServiceProcess.ServiceController.Tests.exe
9,539,584	9,538,560	-1,024	-0.011%	✅	System.IO.Hashing.Tests.exe
9,671,168	9,670,144	-1,024	-0.011%	✅	Microsoft.Extensions.Hosting.Functional.Tests.exe
4,940,288	4,939,776	-512	-0.010%	✅	coreclr.dll
10,935,808	10,934,784	-1,024	-0.009%	✅	System.Runtime.Intrinsics.Tests.exe
11,610,112	11,609,088	-1,024	-0.009%	✅	System.Resources.Extensions.Tests.exe
11,193,856	11,192,832	-1,024	-0.009%	✅	System.Text.Encodings.Web.Tests.exe
12,287,488	12,286,464	-1,024	-0.008%	✅	System.Net.NetworkInformation.Functional.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Nls.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Tests.exe
9,039,360	9,038,848	-512	-0.006%	✅	Microsoft.Extensions.FileSystemGlobbing.Tests.exe
8,558,080	8,557,568	-512	-0.006%	✅	System.Text.Encoding.Extensions.Tests.exe
8,704,512	8,704,000	-512	-0.006%	✅	System.Security.SecureString.Tests.exe
8,701,440	8,700,928	-512	-0.006%	✅	System.Security.Cryptography.ProtectedData.Tests.exe
8,688,128	8,687,616	-512	-0.006%	✅	System.Runtime.InteropServices.ComDisabled.Tests.exe
9,143,808	9,143,296	-512	-0.006%	✅	System.Security.AccessControl.Tests.exe
9,025,536	9,025,024	-512	-0.006%	✅	System.Reflection.TypeExtensions.Tests.exe
8,812,032	8,811,520	-512	-0.006%	✅	System.Resources.Reader.Tests.exe
9,083,392	9,082,880	-512	-0.006%	✅	System.ValueTuple.Tests.exe
8,606,208	8,605,696	-512	-0.006%	✅	System.Resources.Writer.Tests.exe
8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
8,863,232	8,862,720	-512	-0.006%	✅	System.Reflection.Extensions.Tests.exe
8,670,208	8,669,696	-512	-0.006%	✅	System.Runtime.Handles.Tests.exe
9,165,824	9,165,312	-512	-0.006%	✅	System.Globalization.Calendars.Tests.exe
8,543,744	8,543,232	-512	-0.006%	✅	System.IO.FileSystem.Primitives.Tests.exe
8,592,384	8,591,872	-512	-0.006%	✅	Microsoft.Bcl.Numerics.Tests.exe
8,952,832	8,952,320	-512	-0.006%	✅	Microsoft.Bcl.Memory.Tests.exe
8,717,312	8,716,800	-512	-0.006%	✅	System.Diagnostics.FileVersionInfo.Tests.exe
8,700,416	8,699,904	-512	-0.006%	✅	System.IO.FileSystem.Manual.Tests.exe
8,929,792	8,929,280	-512	-0.006%	✅	System.IO.Pipes.AccessControl.Tests.exe
8,624,128	8,623,616	-512	-0.006%	✅	System.Composition.Runtime.Tests.exe
9,108,992	9,108,480	-512	-0.006%	✅	System.IO.FileSystem.AccessControl.Tests.exe
8,559,104	8,558,592	-512	-0.006%	✅	System.Composition.AttributeModel.Tests.exe
8,759,296	8,758,784	-512	-0.006%	✅	Invariant.Tests.exe
8,547,840	8,547,328	-512	-0.006%	✅	System.ComponentModel.Tests.exe
9,161,728	9,161,216	-512	-0.006%	✅	System.ComponentModel.Primitives.Tests.exe
8,959,488	8,958,976	-512	-0.006%	✅	System.Threading.AccessControl.Tests.exe
8,991,232	8,990,720	-512	-0.006%	✅	Microsoft.Win32.Registry.Tests.exe
8,647,680	8,647,168	-512	-0.006%	✅	Microsoft.Win32.Registry.AccessControl.Tests.exe
8,549,376	8,548,864	-512	-0.006%	✅	System.Diagnostics.Tools.Tests.exe
8,664,576	8,664,064	-512	-0.006%	✅	Microsoft.Win32.Primitives.Tests.exe
9,750,016	9,749,504	-512	-0.005%	✅	System.Collections.Specialized.Tests.exe
22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
9,852,928	9,852,416	-512	-0.005%	✅	System.Formats.Nrbf.Tests.exe
9,763,328	9,762,816	-512	-0.005%	✅	System.Formats.Asn1.Tests.exe
9,361,408	9,360,896	-512	-0.005%	✅	System.Security.Permissions.Tests.exe
11,048,448	11,047,936	-512	-0.005%	✅	System.Runtime.Numerics.Tests.exe
9,627,136	9,626,624	-512	-0.005%	✅	System.Diagnostics.EventLog.Tests.exe
18,779,136	18,778,112	-1,024	-0.005%	✅	System.Numerics.Vectors.Tests.exe
9,746,432	9,745,920	-512	-0.005%	✅	System.Threading.RateLimiting.Tests.exe
9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
9,949,696	9,949,184	-512	-0.005%	✅	System.Collections.NonGeneric.Tests.exe
9,486,848	9,486,336	-512	-0.005%	✅	Microsoft.Extensions.Configuration.Ini.Tests.exe
13,553,664	13,554,176	+512	+0.004%	❌	crossgen2.exe
11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
11,381,248	11,380,736	-512	-0.004%	✅	System.Net.Security.Unit.Tests.exe
15,545,856	15,545,344	-512	-0.003%	✅	System.Linq.Tests.exe
17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

[dotnet-policy-service]

Tagging subscribers to this area: @agocke
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[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
18,947,584	18,936,832	-10,752	-0.057%	✅	System.Runtime.Caching.Tests.exe
17,168,896	17,159,168	-9,728	-0.057%	✅	System.Runtime.Serialization.Formatters.Disabled.Tests.exe
17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
17,223,168	17,213,952	-9,216	-0.054%	✅	System.Net.ServicePoint.Tests.exe
18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
17,363,968	17,354,752	-9,216	-0.053%	✅	Microsoft.Win32.SystemEvents.Tests.exe
17,306,112	17,296,896	-9,216	-0.053%	✅	System.Security.Claims.Tests.exe
18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
17,369,088	17,360,384	-8,704	-0.050%	✅	System.Diagnostics.StackTrace.Tests.exe
18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
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19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
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21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
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11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
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33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
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9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
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10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
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33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
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8,606,208	8,605,696	-512	-0.006%	✅	System.Resources.Writer.Tests.exe
8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
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22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
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9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
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11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
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17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

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[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
18,947,584	18,936,832	-10,752	-0.057%	✅	System.Runtime.Caching.Tests.exe
17,168,896	17,159,168	-9,728	-0.057%	✅	System.Runtime.Serialization.Formatters.Disabled.Tests.exe
17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
17,223,168	17,213,952	-9,216	-0.054%	✅	System.Net.ServicePoint.Tests.exe
18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
17,363,968	17,354,752	-9,216	-0.053%	✅	Microsoft.Win32.SystemEvents.Tests.exe
17,306,112	17,296,896	-9,216	-0.053%	✅	System.Security.Claims.Tests.exe
18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
17,369,088	17,360,384	-8,704	-0.050%	✅	System.Diagnostics.StackTrace.Tests.exe
18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
19,876,864	19,867,136	-9,728	-0.049%	✅	System.Text.Encoding.Tests.exe
17,670,656	17,661,952	-8,704	-0.049%	✅	System.Buffers.Tests.exe
19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
12,425,728	12,420,608	-5,120	-0.041%	✅	System.Xml.Linq.SDMSample.Tests.exe
21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
15,048,192	15,043,584	-4,608	-0.031%	✅	System.Data.DataSetExtensions.Tests.exe
16,673,280	16,668,160	-5,120	-0.031%	✅	System.Xml.Linq.Properties.Tests.exe
11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
17,123,840	17,118,720	-5,120	-0.030%	✅	System.Xml.Linq.TreeManipulation.Tests.exe
33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
18,381,312	18,376,704	-4,608	-0.025%	✅	Microsoft.Extensions.Primitives.Tests.exe
20,099,584	20,094,464	-5,120	-0.025%	✅	Microsoft.Extensions.Configuration.Json.Tests.exe
10,521,600	10,519,040	-2,560	-0.024%	✅	Microsoft.Extensions.Options.Tests.exe
16,973,824	16,977,920	+4,096	+0.024%	❌	System.Private.CoreLib.dll
20,038,656	20,034,048	-4,608	-0.023%	✅	Microsoft.Extensions.Configuration.UserSecrets.Tests.exe
19,972,096	19,967,488	-4,608	-0.023%	✅	Microsoft.Extensions.Logging.Tests.exe
9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
18,356,224	18,352,128	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Composite.Tests.exe
44,814,336	44,804,608	-9,728	-0.022%	✅	System.Runtime.Tests.exe
18,774,016	18,769,920	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Physical.Tests.exe
18,491,904	18,487,808	-4,096	-0.022%	✅	Microsoft.Extensions.Configuration.Tests.exe
9,346,560	9,344,512	-2,048	-0.022%	✅	Microsoft.Extensions.Diagnostics.Abstractions.Tests.exe
10,118,656	10,116,608	-2,048	-0.020%	✅	Microsoft.Extensions.Caching.Memory.Tests.exe
30,107,136	30,101,504	-5,632	-0.019%	✅	Microsoft.Extensions.DependencyModel.Tests.exe
10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
8,989,696	8,988,160	-1,536	-0.017%	✅	System.Net.Primitives.Pal.Tests.exe
33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
9,454,080	9,452,544	-1,536	-0.016%	✅	Microsoft.Extensions.Logging.Testing.Tests.exe
9,630,720	9,629,184	-1,536	-0.016%	✅	System.Composition.Convention.Tests.exe
9,314,816	9,313,280	-1,536	-0.016%	✅	System.Net.Primitives.UnitTests.Tests.exe
11,484,160	11,482,624	-1,536	-0.013%	✅	System.IO.Ports.Tests.exe
8,601,600	8,600,576	-1,024	-0.012%	✅	Microsoft.Extensions.Hosting.Abstractions.Tests.exe
8,720,384	8,719,360	-1,024	-0.012%	✅	System.Private.Uri.Unit.Tests.exe
8,546,816	8,545,792	-1,024	-0.012%	✅	System.Runtime.CompilerServices.VisualC.Tests.exe
8,653,312	8,652,288	-1,024	-0.012%	✅	System.Globalization.CalendarsWithConfigSwitch.Tests.exe
8,836,608	8,835,584	-1,024	-0.012%	✅	System.Console.Manual.Tests.exe
9,364,480	9,363,456	-1,024	-0.011%	✅	System.Reflection.Context.Tests.exe
9,041,408	9,040,384	-1,024	-0.011%	✅	System.Net.NameResolution.Pal.Tests.exe
9,646,592	9,645,568	-1,024	-0.011%	✅	System.Private.Uri.Functional.Tests.exe
9,704,448	9,703,424	-1,024	-0.011%	✅	System.Text.RegularExpressions.Unit.Tests.exe
9,206,272	9,205,248	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.EnvironmentVariables.Tests.exe
9,004,032	9,003,008	-1,024	-0.011%	✅	System.Runtime.Serialization.Primitives.Tests.exe
9,056,256	9,055,232	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.CommandLine.Tests.exe
9,216,512	9,215,488	-1,024	-0.011%	✅	System.ServiceProcess.ServiceController.Tests.exe
9,539,584	9,538,560	-1,024	-0.011%	✅	System.IO.Hashing.Tests.exe
9,671,168	9,670,144	-1,024	-0.011%	✅	Microsoft.Extensions.Hosting.Functional.Tests.exe
4,940,288	4,939,776	-512	-0.010%	✅	coreclr.dll
10,935,808	10,934,784	-1,024	-0.009%	✅	System.Runtime.Intrinsics.Tests.exe
11,610,112	11,609,088	-1,024	-0.009%	✅	System.Resources.Extensions.Tests.exe
11,193,856	11,192,832	-1,024	-0.009%	✅	System.Text.Encodings.Web.Tests.exe
12,287,488	12,286,464	-1,024	-0.008%	✅	System.Net.NetworkInformation.Functional.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Nls.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Tests.exe
9,039,360	9,038,848	-512	-0.006%	✅	Microsoft.Extensions.FileSystemGlobbing.Tests.exe
8,558,080	8,557,568	-512	-0.006%	✅	System.Text.Encoding.Extensions.Tests.exe
8,704,512	8,704,000	-512	-0.006%	✅	System.Security.SecureString.Tests.exe
8,701,440	8,700,928	-512	-0.006%	✅	System.Security.Cryptography.ProtectedData.Tests.exe
8,688,128	8,687,616	-512	-0.006%	✅	System.Runtime.InteropServices.ComDisabled.Tests.exe
9,143,808	9,143,296	-512	-0.006%	✅	System.Security.AccessControl.Tests.exe
9,025,536	9,025,024	-512	-0.006%	✅	System.Reflection.TypeExtensions.Tests.exe
8,812,032	8,811,520	-512	-0.006%	✅	System.Resources.Reader.Tests.exe
9,083,392	9,082,880	-512	-0.006%	✅	System.ValueTuple.Tests.exe
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8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
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8,670,208	8,669,696	-512	-0.006%	✅	System.Runtime.Handles.Tests.exe
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8,717,312	8,716,800	-512	-0.006%	✅	System.Diagnostics.FileVersionInfo.Tests.exe
8,700,416	8,699,904	-512	-0.006%	✅	System.IO.FileSystem.Manual.Tests.exe
8,929,792	8,929,280	-512	-0.006%	✅	System.IO.Pipes.AccessControl.Tests.exe
8,624,128	8,623,616	-512	-0.006%	✅	System.Composition.Runtime.Tests.exe
9,108,992	9,108,480	-512	-0.006%	✅	System.IO.FileSystem.AccessControl.Tests.exe
8,559,104	8,558,592	-512	-0.006%	✅	System.Composition.AttributeModel.Tests.exe
8,759,296	8,758,784	-512	-0.006%	✅	Invariant.Tests.exe
8,547,840	8,547,328	-512	-0.006%	✅	System.ComponentModel.Tests.exe
9,161,728	9,161,216	-512	-0.006%	✅	System.ComponentModel.Primitives.Tests.exe
8,959,488	8,958,976	-512	-0.006%	✅	System.Threading.AccessControl.Tests.exe
8,991,232	8,990,720	-512	-0.006%	✅	Microsoft.Win32.Registry.Tests.exe
8,647,680	8,647,168	-512	-0.006%	✅	Microsoft.Win32.Registry.AccessControl.Tests.exe
8,549,376	8,548,864	-512	-0.006%	✅	System.Diagnostics.Tools.Tests.exe
8,664,576	8,664,064	-512	-0.006%	✅	Microsoft.Win32.Primitives.Tests.exe
9,750,016	9,749,504	-512	-0.005%	✅	System.Collections.Specialized.Tests.exe
22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
9,852,928	9,852,416	-512	-0.005%	✅	System.Formats.Nrbf.Tests.exe
9,763,328	9,762,816	-512	-0.005%	✅	System.Formats.Asn1.Tests.exe
9,361,408	9,360,896	-512	-0.005%	✅	System.Security.Permissions.Tests.exe
11,048,448	11,047,936	-512	-0.005%	✅	System.Runtime.Numerics.Tests.exe
9,627,136	9,626,624	-512	-0.005%	✅	System.Diagnostics.EventLog.Tests.exe
18,779,136	18,778,112	-1,024	-0.005%	✅	System.Numerics.Vectors.Tests.exe
9,746,432	9,745,920	-512	-0.005%	✅	System.Threading.RateLimiting.Tests.exe
9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
9,949,696	9,949,184	-512	-0.005%	✅	System.Collections.NonGeneric.Tests.exe
9,486,848	9,486,336	-512	-0.005%	✅	Microsoft.Extensions.Configuration.Ini.Tests.exe
13,553,664	13,554,176	+512	+0.004%	❌	crossgen2.exe
11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
11,381,248	11,380,736	-512	-0.004%	✅	System.Net.Security.Unit.Tests.exe
15,545,856	15,545,344	-512	-0.003%	✅	System.Linq.Tests.exe
17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

[dotnet-policy-service]

Tagging subscribers to this area: @agocke
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[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
18,947,584	18,936,832	-10,752	-0.057%	✅	System.Runtime.Caching.Tests.exe
17,168,896	17,159,168	-9,728	-0.057%	✅	System.Runtime.Serialization.Formatters.Disabled.Tests.exe
17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
17,223,168	17,213,952	-9,216	-0.054%	✅	System.Net.ServicePoint.Tests.exe
18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
17,363,968	17,354,752	-9,216	-0.053%	✅	Microsoft.Win32.SystemEvents.Tests.exe
17,306,112	17,296,896	-9,216	-0.053%	✅	System.Security.Claims.Tests.exe
18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
17,369,088	17,360,384	-8,704	-0.050%	✅	System.Diagnostics.StackTrace.Tests.exe
18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
19,876,864	19,867,136	-9,728	-0.049%	✅	System.Text.Encoding.Tests.exe
17,670,656	17,661,952	-8,704	-0.049%	✅	System.Buffers.Tests.exe
19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
12,425,728	12,420,608	-5,120	-0.041%	✅	System.Xml.Linq.SDMSample.Tests.exe
21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
15,048,192	15,043,584	-4,608	-0.031%	✅	System.Data.DataSetExtensions.Tests.exe
16,673,280	16,668,160	-5,120	-0.031%	✅	System.Xml.Linq.Properties.Tests.exe
11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
17,123,840	17,118,720	-5,120	-0.030%	✅	System.Xml.Linq.TreeManipulation.Tests.exe
33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
18,381,312	18,376,704	-4,608	-0.025%	✅	Microsoft.Extensions.Primitives.Tests.exe
20,099,584	20,094,464	-5,120	-0.025%	✅	Microsoft.Extensions.Configuration.Json.Tests.exe
10,521,600	10,519,040	-2,560	-0.024%	✅	Microsoft.Extensions.Options.Tests.exe
16,973,824	16,977,920	+4,096	+0.024%	❌	System.Private.CoreLib.dll
20,038,656	20,034,048	-4,608	-0.023%	✅	Microsoft.Extensions.Configuration.UserSecrets.Tests.exe
19,972,096	19,967,488	-4,608	-0.023%	✅	Microsoft.Extensions.Logging.Tests.exe
9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
18,356,224	18,352,128	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Composite.Tests.exe
44,814,336	44,804,608	-9,728	-0.022%	✅	System.Runtime.Tests.exe
18,774,016	18,769,920	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Physical.Tests.exe
18,491,904	18,487,808	-4,096	-0.022%	✅	Microsoft.Extensions.Configuration.Tests.exe
9,346,560	9,344,512	-2,048	-0.022%	✅	Microsoft.Extensions.Diagnostics.Abstractions.Tests.exe
10,118,656	10,116,608	-2,048	-0.020%	✅	Microsoft.Extensions.Caching.Memory.Tests.exe
30,107,136	30,101,504	-5,632	-0.019%	✅	Microsoft.Extensions.DependencyModel.Tests.exe
10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
8,989,696	8,988,160	-1,536	-0.017%	✅	System.Net.Primitives.Pal.Tests.exe
33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
9,454,080	9,452,544	-1,536	-0.016%	✅	Microsoft.Extensions.Logging.Testing.Tests.exe
9,630,720	9,629,184	-1,536	-0.016%	✅	System.Composition.Convention.Tests.exe
9,314,816	9,313,280	-1,536	-0.016%	✅	System.Net.Primitives.UnitTests.Tests.exe
11,484,160	11,482,624	-1,536	-0.013%	✅	System.IO.Ports.Tests.exe
8,601,600	8,600,576	-1,024	-0.012%	✅	Microsoft.Extensions.Hosting.Abstractions.Tests.exe
8,720,384	8,719,360	-1,024	-0.012%	✅	System.Private.Uri.Unit.Tests.exe
8,546,816	8,545,792	-1,024	-0.012%	✅	System.Runtime.CompilerServices.VisualC.Tests.exe
8,653,312	8,652,288	-1,024	-0.012%	✅	System.Globalization.CalendarsWithConfigSwitch.Tests.exe
8,836,608	8,835,584	-1,024	-0.012%	✅	System.Console.Manual.Tests.exe
9,364,480	9,363,456	-1,024	-0.011%	✅	System.Reflection.Context.Tests.exe
9,041,408	9,040,384	-1,024	-0.011%	✅	System.Net.NameResolution.Pal.Tests.exe
9,646,592	9,645,568	-1,024	-0.011%	✅	System.Private.Uri.Functional.Tests.exe
9,704,448	9,703,424	-1,024	-0.011%	✅	System.Text.RegularExpressions.Unit.Tests.exe
9,206,272	9,205,248	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.EnvironmentVariables.Tests.exe
9,004,032	9,003,008	-1,024	-0.011%	✅	System.Runtime.Serialization.Primitives.Tests.exe
9,056,256	9,055,232	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.CommandLine.Tests.exe
9,216,512	9,215,488	-1,024	-0.011%	✅	System.ServiceProcess.ServiceController.Tests.exe
9,539,584	9,538,560	-1,024	-0.011%	✅	System.IO.Hashing.Tests.exe
9,671,168	9,670,144	-1,024	-0.011%	✅	Microsoft.Extensions.Hosting.Functional.Tests.exe
4,940,288	4,939,776	-512	-0.010%	✅	coreclr.dll
10,935,808	10,934,784	-1,024	-0.009%	✅	System.Runtime.Intrinsics.Tests.exe
11,610,112	11,609,088	-1,024	-0.009%	✅	System.Resources.Extensions.Tests.exe
11,193,856	11,192,832	-1,024	-0.009%	✅	System.Text.Encodings.Web.Tests.exe
12,287,488	12,286,464	-1,024	-0.008%	✅	System.Net.NetworkInformation.Functional.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Nls.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Tests.exe
9,039,360	9,038,848	-512	-0.006%	✅	Microsoft.Extensions.FileSystemGlobbing.Tests.exe
8,558,080	8,557,568	-512	-0.006%	✅	System.Text.Encoding.Extensions.Tests.exe
8,704,512	8,704,000	-512	-0.006%	✅	System.Security.SecureString.Tests.exe
8,701,440	8,700,928	-512	-0.006%	✅	System.Security.Cryptography.ProtectedData.Tests.exe
8,688,128	8,687,616	-512	-0.006%	✅	System.Runtime.InteropServices.ComDisabled.Tests.exe
9,143,808	9,143,296	-512	-0.006%	✅	System.Security.AccessControl.Tests.exe
9,025,536	9,025,024	-512	-0.006%	✅	System.Reflection.TypeExtensions.Tests.exe
8,812,032	8,811,520	-512	-0.006%	✅	System.Resources.Reader.Tests.exe
9,083,392	9,082,880	-512	-0.006%	✅	System.ValueTuple.Tests.exe
8,606,208	8,605,696	-512	-0.006%	✅	System.Resources.Writer.Tests.exe
8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
8,863,232	8,862,720	-512	-0.006%	✅	System.Reflection.Extensions.Tests.exe
8,670,208	8,669,696	-512	-0.006%	✅	System.Runtime.Handles.Tests.exe
9,165,824	9,165,312	-512	-0.006%	✅	System.Globalization.Calendars.Tests.exe
8,543,744	8,543,232	-512	-0.006%	✅	System.IO.FileSystem.Primitives.Tests.exe
8,592,384	8,591,872	-512	-0.006%	✅	Microsoft.Bcl.Numerics.Tests.exe
8,952,832	8,952,320	-512	-0.006%	✅	Microsoft.Bcl.Memory.Tests.exe
8,717,312	8,716,800	-512	-0.006%	✅	System.Diagnostics.FileVersionInfo.Tests.exe
8,700,416	8,699,904	-512	-0.006%	✅	System.IO.FileSystem.Manual.Tests.exe
8,929,792	8,929,280	-512	-0.006%	✅	System.IO.Pipes.AccessControl.Tests.exe
8,624,128	8,623,616	-512	-0.006%	✅	System.Composition.Runtime.Tests.exe
9,108,992	9,108,480	-512	-0.006%	✅	System.IO.FileSystem.AccessControl.Tests.exe
8,559,104	8,558,592	-512	-0.006%	✅	System.Composition.AttributeModel.Tests.exe
8,759,296	8,758,784	-512	-0.006%	✅	Invariant.Tests.exe
8,547,840	8,547,328	-512	-0.006%	✅	System.ComponentModel.Tests.exe
9,161,728	9,161,216	-512	-0.006%	✅	System.ComponentModel.Primitives.Tests.exe
8,959,488	8,958,976	-512	-0.006%	✅	System.Threading.AccessControl.Tests.exe
8,991,232	8,990,720	-512	-0.006%	✅	Microsoft.Win32.Registry.Tests.exe
8,647,680	8,647,168	-512	-0.006%	✅	Microsoft.Win32.Registry.AccessControl.Tests.exe
8,549,376	8,548,864	-512	-0.006%	✅	System.Diagnostics.Tools.Tests.exe
8,664,576	8,664,064	-512	-0.006%	✅	Microsoft.Win32.Primitives.Tests.exe
9,750,016	9,749,504	-512	-0.005%	✅	System.Collections.Specialized.Tests.exe
22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
9,852,928	9,852,416	-512	-0.005%	✅	System.Formats.Nrbf.Tests.exe
9,763,328	9,762,816	-512	-0.005%	✅	System.Formats.Asn1.Tests.exe
9,361,408	9,360,896	-512	-0.005%	✅	System.Security.Permissions.Tests.exe
11,048,448	11,047,936	-512	-0.005%	✅	System.Runtime.Numerics.Tests.exe
9,627,136	9,626,624	-512	-0.005%	✅	System.Diagnostics.EventLog.Tests.exe
18,779,136	18,778,112	-1,024	-0.005%	✅	System.Numerics.Vectors.Tests.exe
9,746,432	9,745,920	-512	-0.005%	✅	System.Threading.RateLimiting.Tests.exe
9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
9,949,696	9,949,184	-512	-0.005%	✅	System.Collections.NonGeneric.Tests.exe
9,486,848	9,486,336	-512	-0.005%	✅	Microsoft.Extensions.Configuration.Ini.Tests.exe
13,553,664	13,554,176	+512	+0.004%	❌	crossgen2.exe
11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
11,381,248	11,380,736	-512	-0.004%	✅	System.Net.Security.Unit.Tests.exe
15,545,856	15,545,344	-512	-0.003%	✅	System.Linq.Tests.exe
17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

ValueTask backed by IValueTaskSource can suspend without allocating. However, runtime async did not support this when calling a ValueTask returning method through a runtime async callable thunk. In that case we would always allocate in the case where the ValueTask suspended.

This adds a custom ValueTaskContinuation that replaces the existing ValueTaskSourceNotifier mechanism. We now cache a ValueTaskContinuation instance and reuse it if possible whenever suspending for a ValueTask.

The same approach could be used to avoid allocations for runtime async callable thunks for task-returning methods.

cc @VSadov

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Tagging subscribers to this area: @agocke
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[Copilot]

Pull request overview

This PR updates CoreCLR’s runtime-async callable thunk path for ValueTask/ValueTask<T> so that suspending on ValueTask backed by IValueTaskSource can reuse a cached continuation object rather than allocating per-suspension, and removes the older ValueTaskSourceNotifier / AsTaskOrNotifier mechanism.

Changes:

• Introduces AsyncHelpers.TransparentAwaitValueTask* and a ValueTaskContinuation type that integrates with runtime-async suspension/resumption and is cached in TLS for reuse.
• Removes ValueTask.AsTaskOrNotifier and the ValueTaskSourceNotifier helper type from ValueTask.
• Adjusts VM continuation type handling to distinguish continuation subtypes that do have metadata (managed subclasses) vs the dynamically-created metadata-less ones, including DAC support.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Removes AsTaskOrNotifier and deletes ValueTaskSourceNotifier.
src/coreclr/vm/vars.hpp	Adds global g_singletonContinuationEEClass declaration for continuation metadata detection.
src/coreclr/vm/vars.cpp	Adds global g_singletonContinuationEEClass definition.
src/coreclr/vm/typehandle.inl	Avoids “upcasting” continuations that have real metadata.
src/coreclr/vm/typehandle.h	Adds TypeHandle::IsContinuationWithMetadata().
src/coreclr/vm/typehandle.cpp	Implements TypeHandle::IsContinuationWithMetadata() and relaxes class-object allocation restriction for metadata continuations.
src/coreclr/vm/methodtable.h	Adds MethodTable::IsContinuationWithMetadata() and relaxes asserts/preconditions for metadata continuations.
src/coreclr/vm/methodtable.cpp	Implements MethodTable::IsContinuationWithMetadata() and updates continuation-related special-casing.
src/coreclr/vm/corelib.h	Removes binder entries for ValueTask.AsTaskOrNotifier; adds binder entries for TransparentAwaitValueTask*.
src/coreclr/vm/asyncthunks.cpp	Emits thunk IL that tail-awaits via TransparentAwaitValueTask* instead of AsTaskOrNotifier + TransparentAwait.
src/coreclr/vm/asynccontinuations.cpp	Moves singleton continuation EEClass storage to global g_singletonContinuationEEClass.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Updates managed type-system thunk emission to call TransparentAwaitValueTask* and TailAwait.
src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs	Adds ValueTaskContinuation, TLS caching, and TransparentAwaitValueTask*; updates suspension handling to use it.
src/coreclr/inc/dacvars.h	Exposes g_singletonContinuationEEClass to DAC.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Updates continuation canonical-MT validity logic to account for metadata continuations.

[VSadov]

Nice! Instead of caching and reusing ValueTaskSourceNotifier, we now cache/reuse the entire head continuation.

A scenario that awaits in a loop some ValueTaskSource wrapper (like reading chunks from a pipe) can run allocation-free.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

Also, we probably need to introduce a runtime async mechanism similar to PoolingAsyncValueTaskMethodBuilder -- e.g. apply [PoolContinuations] on a runtime async method and it would cache continuations for that method following that scheme too.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/AsyncHelpers.CoreCLR.cs:1

• The XML doc block still describes awaiting ValueTask, but TransparentAwait now accepts Task only, while ValueTask awaiting is handled by TransparentAwaitValueTask* above. Please update/move this comment so TransparentAwait’s docs describe only the Task scenario, and place the ValueTask-specific explanation on TransparentAwaitValueTask / TransparentAwaitValueTaskOfT.

// Licensed to the .NET Foundation under one or more agreements.

[jakobbotsch]

I think I will use the same caching scheme as in #55955, which in addition to the TLS cached object also has a per-core cache.

I think I will do that separately. Right now the caching is essentially free since we can store it in the runtime async TLS that we already needed to access. If we introduce the per-core cache we will be paying more when the TLS cache doesn't hit, so I want to make sure I have some benchmarks for this.

[VSadov]

I think I will do that separately

Per thread caching of 1 head continuation is probably the most effective as we reduce necessary allocations for that scenario to none.

Additional caching may cost more while having less impact. It makes sense to look at that separately.

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

[jakobbotsch]

Also some decent size improvements for NativeAOT since the thunks no longer need a suspension/resumption point:

BaseSize	DiffSize	Delta	Percent	Improved	Name
16,852,992	16,716,288	-136,704	-0.811%	✅	System.Linq.AsyncEnumerable.Tests.exe
115,198,464	115,079,168	-119,296	-0.104%	✅	System.Text.Json.SourceGeneration.Roslyn4.4.Tests.exe
10,291,200	10,282,496	-8,704	-0.085%	✅	System.Threading.Channels.Tests.exe
12,003,328	11,993,088	-10,240	-0.085%	✅	System.IO.Tests.exe
19,561,472	19,545,088	-16,384	-0.084%	✅	System.IO.Compression.Tests.exe
14,579,712	14,568,960	-10,752	-0.074%	✅	System.Net.WebClient.Tests.exe
20,044,288	20,029,952	-14,336	-0.072%	✅	System.Formats.Tar.Tests.exe
45,556,224	45,524,992	-31,232	-0.069%	✅	System.Security.Cryptography.Tests.exe
21,715,456	21,700,608	-14,848	-0.068%	✅	System.IO.FileSystem.Tests.exe
18,455,552	18,443,264	-12,288	-0.067%	✅	System.Threading.Tasks.Parallel.Tests.exe
18,526,208	18,513,920	-12,288	-0.066%	✅	System.IO.MemoryMappedFiles.Tests.exe
10,067,456	10,060,800	-6,656	-0.066%	✅	System.Net.ServerSentEvents.Tests.exe
17,734,144	17,722,368	-11,776	-0.066%	✅	System.Threading.Tasks.Extensions.Tests.exe
15,771,648	15,761,408	-10,240	-0.065%	✅	System.Windows.Extensions.Tests.exe
19,296,768	19,284,480	-12,288	-0.064%	✅	System.IO.Pipes.Tests.exe
11,286,016	11,278,848	-7,168	-0.064%	✅	System.IO.Compression.Brotli.Tests.exe
19,570,176	19,557,888	-12,288	-0.063%	✅	System.Diagnostics.Process.Tests.exe
20,273,664	20,260,864	-12,800	-0.063%	✅	System.Threading.Tasks.Dataflow.Tests.exe
25,897,984	25,881,600	-16,384	-0.063%	✅	System.Text.Json.SourceGeneration.Roslyn3.11.Tests.exe
11,343,360	11,336,192	-7,168	-0.063%	✅	System.Net.WebSockets.Tests.exe
10,675,200	10,668,544	-6,656	-0.062%	✅	System.IO.Pipelines.Tests.exe
13,250,560	13,242,368	-8,192	-0.062%	✅	System.IO.Packaging.Tests.exe
20,009,984	19,997,696	-12,288	-0.061%	✅	System.Net.WebSockets.Client.Tests.exe
31,281,664	31,263,232	-18,432	-0.059%	✅	System.Net.Http.Functional.Tests.exe
20,942,848	20,930,560	-12,288	-0.059%	✅	System.Net.Quic.Functional.Tests.exe
17,798,656	17,788,416	-10,240	-0.058%	✅	System.Formats.Tar.Manual.Tests.exe
23,142,912	23,129,600	-13,312	-0.058%	✅	System.Threading.Tasks.Tests.exe
18,947,584	18,936,832	-10,752	-0.057%	✅	System.Runtime.Caching.Tests.exe
17,168,896	17,159,168	-9,728	-0.057%	✅	System.Runtime.Serialization.Formatters.Disabled.Tests.exe
17,439,232	17,429,504	-9,728	-0.056%	✅	System.Diagnostics.TraceSource.Tests.exe
17,223,168	17,213,952	-9,216	-0.054%	✅	System.Net.ServicePoint.Tests.exe
18,070,528	18,060,800	-9,728	-0.054%	✅	System.Console.Tests.exe
17,975,296	17,965,568	-9,728	-0.054%	✅	System.Threading.ThreadPool.Tests.exe
18,137,600	18,127,872	-9,728	-0.054%	✅	System.Diagnostics.TextWriterTraceListener.Tests.exe
18,380,800	18,371,072	-9,728	-0.053%	✅	System.Threading.Tests.exe
17,296,896	17,287,680	-9,216	-0.053%	✅	System.Runtime.InteropServices.RuntimeInformation.Tests.exe
17,438,720	17,429,504	-9,216	-0.053%	✅	System.Net.Ping.Functional.Tests.exe
17,244,160	17,234,944	-9,216	-0.053%	✅	System.Runtime.InvariantTimezone.Tests.exe
17,290,240	17,281,024	-9,216	-0.053%	✅	System.Threading.Overlapped.Tests.exe
17,363,968	17,354,752	-9,216	-0.053%	✅	Microsoft.Win32.SystemEvents.Tests.exe
17,306,112	17,296,896	-9,216	-0.053%	✅	System.Security.Claims.Tests.exe
18,594,816	18,585,088	-9,728	-0.052%	✅	ComInterfaceGenerator.Tests.exe
18,692,608	18,682,880	-9,728	-0.052%	✅	Microsoft.Extensions.Logging.Console.Tests.exe
17,578,496	17,569,280	-9,216	-0.052%	✅	MetricOuterLoop1.Tests.exe
17,573,888	17,564,672	-9,216	-0.052%	✅	MetricOuterLoop.Tests.exe
19,688,960	19,678,720	-10,240	-0.052%	✅	System.Net.Http.Unit.Tests.exe
17,975,296	17,966,080	-9,216	-0.051%	✅	System.Threading.ThreadPool.WindowsThreadPool.Tests.exe
28,039,168	28,024,832	-14,336	-0.051%	✅	System.Net.Security.Tests.exe
22,881,280	22,869,504	-11,776	-0.051%	✅	System.Net.Sockets.Tests.exe
19,059,200	19,049,472	-9,728	-0.051%	✅	System.Net.HttpListener.Tests.exe
18,040,832	18,031,616	-9,216	-0.051%	✅	Microsoft.Extensions.Diagnostics.Tests.exe
17,238,528	17,229,824	-8,704	-0.050%	✅	System.ComponentModel.EventBasedAsync.Tests.exe
17,369,088	17,360,384	-8,704	-0.050%	✅	System.Diagnostics.StackTrace.Tests.exe
18,496,512	18,487,296	-9,216	-0.050%	✅	Microsoft.Extensions.Hosting.Systemd.Tests.exe
17,320,448	17,311,744	-8,704	-0.050%	✅	System.Security.Principal.Windows.Tests.exe
17,337,344	17,328,640	-8,704	-0.050%	✅	System.Threading.Timer.Tests.exe
17,668,096	17,659,392	-8,704	-0.049%	✅	System.IO.FileSystem.Watcher.Tests.exe
17,624,576	17,615,872	-8,704	-0.049%	✅	System.Threading.Thread.Tests.exe
19,876,864	19,867,136	-9,728	-0.049%	✅	System.Text.Encoding.Tests.exe
17,670,656	17,661,952	-8,704	-0.049%	✅	System.Buffers.Tests.exe
19,401,216	19,392,000	-9,216	-0.048%	✅	System.Net.Primitives.Functional.Tests.exe
17,161,728	17,153,536	-8,192	-0.048%	✅	IcuAppLocal.Tests.exe
18,184,704	18,176,000	-8,704	-0.048%	✅	System.Text.Encoding.CodePages.Tests.exe
10,061,824	10,057,216	-4,608	-0.046%	✅	System.IO.Compression.ZipFile.Tests.exe
19,087,872	19,079,168	-8,704	-0.046%	✅	Microsoft.Extensions.Hosting.WindowsServices.Tests.exe
21,631,488	21,621,760	-9,728	-0.045%	✅	System.Data.OleDb.Tests.exe
20,581,376	20,572,160	-9,216	-0.045%	✅	System.Diagnostics.DiagnosticSource.Tests.exe
13,877,760	13,871,616	-6,144	-0.044%	✅	Microsoft.Extensions.Configuration.Functional.Tests.exe
19,752,960	19,744,256	-8,704	-0.044%	✅	System.Resources.ResourceManager.Tests.exe
20,748,800	20,739,584	-9,216	-0.044%	✅	System.Collections.Concurrent.Tests.exe
20,463,104	20,454,400	-8,704	-0.043%	✅	System.Reflection.Tests.exe
20,241,408	20,232,704	-8,704	-0.043%	✅	System.Runtime.InteropServices.Tests.exe
20,940,800	20,932,096	-8,704	-0.042%	✅	System.Runtime.Extensions.Tests.exe
12,425,728	12,420,608	-5,120	-0.041%	✅	System.Xml.Linq.SDMSample.Tests.exe
21,210,112	21,201,408	-8,704	-0.041%	✅	System.Net.Requests.Tests.exe
29,510,656	29,498,880	-11,776	-0.040%	✅	System.Net.Http.WinHttpHandler.Functional.Tests.exe
12,858,880	12,853,760	-5,120	-0.040%	✅	System.Xml.Schema.Extensions.Tests.exe
24,283,136	24,273,408	-9,728	-0.040%	✅	Microsoft.Extensions.Http.Tests.exe
14,142,464	14,136,832	-5,632	-0.040%	✅	System.DirectoryServices.Protocols.Tests.exe
10,599,424	10,595,328	-4,096	-0.039%	✅	Common.Tests.exe
9,264,128	9,260,544	-3,584	-0.039%	✅	Microsoft.Bcl.AsyncInterfaces.Tests.exe
14,903,808	14,898,176	-5,632	-0.038%	✅	System.Xml.Linq.Streaming.Tests.exe
13,953,536	13,948,416	-5,120	-0.037%	✅	Microsoft.Extensions.Configuration.Xml.Tests.exe
15,094,784	15,089,152	-5,632	-0.037%	✅	System.Security.Cryptography.Cng.Tests.exe
23,411,712	23,403,008	-8,704	-0.037%	✅	System.Memory.Tests.exe
27,287,040	27,277,312	-9,728	-0.036%	✅	Microsoft.Extensions.Hosting.Unit.Tests.exe
16,117,248	16,111,616	-5,632	-0.035%	✅	System.Data.Odbc.Tests.exe
26,646,528	26,637,312	-9,216	-0.035%	✅	Microsoft.Extensions.Logging.EventSource.Tests.exe
26,441,216	26,432,000	-9,216	-0.035%	✅	System.ComponentModel.TypeConverter.Tests.exe
16,525,312	16,519,680	-5,632	-0.034%	✅	System.Xml.Linq.Events.Tests.exe
16,778,752	16,773,120	-5,632	-0.034%	✅	System.Xml.Linq.Misc.Tests.exe
26,103,808	26,095,104	-8,704	-0.033%	✅	System.Globalization.Tests.exe
26,014,720	26,006,016	-8,704	-0.033%	✅	System.Globalization.Nls.Tests.exe
17,009,664	17,004,032	-5,632	-0.033%	✅	System.Xml.Linq.xNodeReader.Tests.exe
9,675,264	9,672,192	-3,072	-0.032%	✅	System.IO.UnmanagedMemoryStream.Tests.exe
15,048,192	15,043,584	-4,608	-0.031%	✅	System.Data.DataSetExtensions.Tests.exe
16,673,280	16,668,160	-5,120	-0.031%	✅	System.Xml.Linq.Properties.Tests.exe
11,599,360	11,595,776	-3,584	-0.031%	✅	System.Net.Http.Json.Unit.Tests.exe
17,065,984	17,060,864	-5,120	-0.030%	✅	System.Xml.Linq.xNodeBuilder.Tests.exe
20,819,456	20,813,312	-6,144	-0.030%	✅	System.Security.Cryptography.Csp.Tests.exe
17,123,840	17,118,720	-5,120	-0.030%	✅	System.Xml.Linq.TreeManipulation.Tests.exe
33,400,832	33,391,104	-9,728	-0.029%	✅	Microsoft.Bcl.Cryptography.Tests.exe
18,455,040	18,449,920	-5,120	-0.028%	✅	Microsoft.Extensions.Configuration.FileExtensions.Tests.exe
32,762,368	32,753,152	-9,216	-0.028%	✅	System.Linq.Expressions.Tests.exe
15,110,656	15,106,560	-4,096	-0.027%	✅	System.Drawing.Primitives.Tests.exe
18,381,312	18,376,704	-4,608	-0.025%	✅	Microsoft.Extensions.Primitives.Tests.exe
20,099,584	20,094,464	-5,120	-0.025%	✅	Microsoft.Extensions.Configuration.Json.Tests.exe
10,521,600	10,519,040	-2,560	-0.024%	✅	Microsoft.Extensions.Options.Tests.exe
16,973,824	16,977,920	+4,096	+0.024%	❌	System.Private.CoreLib.dll
20,038,656	20,034,048	-4,608	-0.023%	✅	Microsoft.Extensions.Configuration.UserSecrets.Tests.exe
19,972,096	19,967,488	-4,608	-0.023%	✅	Microsoft.Extensions.Logging.Tests.exe
9,351,168	9,349,120	-2,048	-0.022%	✅	System.IO.IsolatedStorage.Tests.exe
9,376,256	9,374,208	-2,048	-0.022%	✅	System.Net.Mail.Unit.Tests.exe
18,356,224	18,352,128	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Composite.Tests.exe
44,814,336	44,804,608	-9,728	-0.022%	✅	System.Runtime.Tests.exe
18,774,016	18,769,920	-4,096	-0.022%	✅	Microsoft.Extensions.FileProviders.Physical.Tests.exe
18,491,904	18,487,808	-4,096	-0.022%	✅	Microsoft.Extensions.Configuration.Tests.exe
9,346,560	9,344,512	-2,048	-0.022%	✅	Microsoft.Extensions.Diagnostics.Abstractions.Tests.exe
10,118,656	10,116,608	-2,048	-0.020%	✅	Microsoft.Extensions.Caching.Memory.Tests.exe
30,107,136	30,101,504	-5,632	-0.019%	✅	Microsoft.Extensions.DependencyModel.Tests.exe
10,508,288	10,506,240	-2,048	-0.019%	✅	System.Net.Http.WinHttpHandler.Unit.Tests.exe
8,563,200	8,561,664	-1,536	-0.018%	✅	System.Diagnostics.Contracts.Tests.exe
8,642,048	8,640,512	-1,536	-0.018%	✅	System.Net.WebHeaderCollection.Tests.exe
8,770,048	8,768,512	-1,536	-0.018%	✅	System.IO.FileSystem.DriveInfo.Tests.exe
12,285,952	12,283,904	-2,048	-0.017%	✅	System.Reflection.Metadata.Tests.exe
8,989,696	8,988,160	-1,536	-0.017%	✅	System.Net.Primitives.Pal.Tests.exe
33,161,216	33,155,584	-5,632	-0.017%	✅	System.Private.Xml.Tests.exe
9,454,080	9,452,544	-1,536	-0.016%	✅	Microsoft.Extensions.Logging.Testing.Tests.exe
9,630,720	9,629,184	-1,536	-0.016%	✅	System.Composition.Convention.Tests.exe
9,314,816	9,313,280	-1,536	-0.016%	✅	System.Net.Primitives.UnitTests.Tests.exe
11,484,160	11,482,624	-1,536	-0.013%	✅	System.IO.Ports.Tests.exe
8,601,600	8,600,576	-1,024	-0.012%	✅	Microsoft.Extensions.Hosting.Abstractions.Tests.exe
8,720,384	8,719,360	-1,024	-0.012%	✅	System.Private.Uri.Unit.Tests.exe
8,546,816	8,545,792	-1,024	-0.012%	✅	System.Runtime.CompilerServices.VisualC.Tests.exe
8,653,312	8,652,288	-1,024	-0.012%	✅	System.Globalization.CalendarsWithConfigSwitch.Tests.exe
8,836,608	8,835,584	-1,024	-0.012%	✅	System.Console.Manual.Tests.exe
9,364,480	9,363,456	-1,024	-0.011%	✅	System.Reflection.Context.Tests.exe
9,041,408	9,040,384	-1,024	-0.011%	✅	System.Net.NameResolution.Pal.Tests.exe
9,646,592	9,645,568	-1,024	-0.011%	✅	System.Private.Uri.Functional.Tests.exe
9,704,448	9,703,424	-1,024	-0.011%	✅	System.Text.RegularExpressions.Unit.Tests.exe
9,206,272	9,205,248	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.EnvironmentVariables.Tests.exe
9,004,032	9,003,008	-1,024	-0.011%	✅	System.Runtime.Serialization.Primitives.Tests.exe
9,056,256	9,055,232	-1,024	-0.011%	✅	Microsoft.Extensions.Configuration.CommandLine.Tests.exe
9,216,512	9,215,488	-1,024	-0.011%	✅	System.ServiceProcess.ServiceController.Tests.exe
9,539,584	9,538,560	-1,024	-0.011%	✅	System.IO.Hashing.Tests.exe
9,671,168	9,670,144	-1,024	-0.011%	✅	Microsoft.Extensions.Hosting.Functional.Tests.exe
4,940,288	4,939,776	-512	-0.010%	✅	coreclr.dll
10,935,808	10,934,784	-1,024	-0.009%	✅	System.Runtime.Intrinsics.Tests.exe
11,610,112	11,609,088	-1,024	-0.009%	✅	System.Resources.Extensions.Tests.exe
11,193,856	11,192,832	-1,024	-0.009%	✅	System.Text.Encodings.Web.Tests.exe
12,287,488	12,286,464	-1,024	-0.008%	✅	System.Net.NetworkInformation.Functional.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Nls.Tests.exe
15,399,936	15,398,912	-1,024	-0.007%	✅	System.Globalization.Extensions.Tests.exe
9,039,360	9,038,848	-512	-0.006%	✅	Microsoft.Extensions.FileSystemGlobbing.Tests.exe
8,558,080	8,557,568	-512	-0.006%	✅	System.Text.Encoding.Extensions.Tests.exe
8,704,512	8,704,000	-512	-0.006%	✅	System.Security.SecureString.Tests.exe
8,701,440	8,700,928	-512	-0.006%	✅	System.Security.Cryptography.ProtectedData.Tests.exe
8,688,128	8,687,616	-512	-0.006%	✅	System.Runtime.InteropServices.ComDisabled.Tests.exe
9,143,808	9,143,296	-512	-0.006%	✅	System.Security.AccessControl.Tests.exe
9,025,536	9,025,024	-512	-0.006%	✅	System.Reflection.TypeExtensions.Tests.exe
8,812,032	8,811,520	-512	-0.006%	✅	System.Resources.Reader.Tests.exe
9,083,392	9,082,880	-512	-0.006%	✅	System.ValueTuple.Tests.exe
8,606,208	8,605,696	-512	-0.006%	✅	System.Resources.Writer.Tests.exe
8,817,664	8,817,152	-512	-0.006%	✅	System.Web.HttpUtility.Tests.exe
8,863,232	8,862,720	-512	-0.006%	✅	System.Reflection.Extensions.Tests.exe
8,670,208	8,669,696	-512	-0.006%	✅	System.Runtime.Handles.Tests.exe
9,165,824	9,165,312	-512	-0.006%	✅	System.Globalization.Calendars.Tests.exe
8,543,744	8,543,232	-512	-0.006%	✅	System.IO.FileSystem.Primitives.Tests.exe
8,592,384	8,591,872	-512	-0.006%	✅	Microsoft.Bcl.Numerics.Tests.exe
8,952,832	8,952,320	-512	-0.006%	✅	Microsoft.Bcl.Memory.Tests.exe
8,717,312	8,716,800	-512	-0.006%	✅	System.Diagnostics.FileVersionInfo.Tests.exe
8,700,416	8,699,904	-512	-0.006%	✅	System.IO.FileSystem.Manual.Tests.exe
8,929,792	8,929,280	-512	-0.006%	✅	System.IO.Pipes.AccessControl.Tests.exe
8,624,128	8,623,616	-512	-0.006%	✅	System.Composition.Runtime.Tests.exe
9,108,992	9,108,480	-512	-0.006%	✅	System.IO.FileSystem.AccessControl.Tests.exe
8,559,104	8,558,592	-512	-0.006%	✅	System.Composition.AttributeModel.Tests.exe
8,759,296	8,758,784	-512	-0.006%	✅	Invariant.Tests.exe
8,547,840	8,547,328	-512	-0.006%	✅	System.ComponentModel.Tests.exe
9,161,728	9,161,216	-512	-0.006%	✅	System.ComponentModel.Primitives.Tests.exe
8,959,488	8,958,976	-512	-0.006%	✅	System.Threading.AccessControl.Tests.exe
8,991,232	8,990,720	-512	-0.006%	✅	Microsoft.Win32.Registry.Tests.exe
8,647,680	8,647,168	-512	-0.006%	✅	Microsoft.Win32.Registry.AccessControl.Tests.exe
8,549,376	8,548,864	-512	-0.006%	✅	System.Diagnostics.Tools.Tests.exe
8,664,576	8,664,064	-512	-0.006%	✅	Microsoft.Win32.Primitives.Tests.exe
9,750,016	9,749,504	-512	-0.005%	✅	System.Collections.Specialized.Tests.exe
22,340,608	22,339,584	-1,024	-0.005%	✅	System.Security.Cryptography.Pkcs.Tests.exe
9,852,928	9,852,416	-512	-0.005%	✅	System.Formats.Nrbf.Tests.exe
9,763,328	9,762,816	-512	-0.005%	✅	System.Formats.Asn1.Tests.exe
9,361,408	9,360,896	-512	-0.005%	✅	System.Security.Permissions.Tests.exe
11,048,448	11,047,936	-512	-0.005%	✅	System.Runtime.Numerics.Tests.exe
9,627,136	9,626,624	-512	-0.005%	✅	System.Diagnostics.EventLog.Tests.exe
18,779,136	18,778,112	-1,024	-0.005%	✅	System.Numerics.Vectors.Tests.exe
9,746,432	9,745,920	-512	-0.005%	✅	System.Threading.RateLimiting.Tests.exe
9,961,472	9,960,960	-512	-0.005%	✅	LibraryImportGenerator.Tests.exe
9,949,696	9,949,184	-512	-0.005%	✅	System.Collections.NonGeneric.Tests.exe
9,486,848	9,486,336	-512	-0.005%	✅	Microsoft.Extensions.Configuration.Ini.Tests.exe
13,553,664	13,554,176	+512	+0.004%	❌	crossgen2.exe
11,796,480	11,795,968	-512	-0.004%	✅	System.Security.Cryptography.Cose.Tests.exe
11,381,248	11,380,736	-512	-0.004%	✅	System.Net.Security.Unit.Tests.exe
15,545,856	15,545,344	-512	-0.003%	✅	System.Linq.Tests.exe
17,838,592	17,838,080	-512	-0.003%	✅	System.Collections.Tests.exe

[Copilot]

Pull request overview

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.