Support async generic virtual methods by MichalStrehovsky · Pull Request #121524 · dotnet/runtime

MichalStrehovsky · 2025-11-11T12:47:53Z

Since generic virtual method dispatch is based on RuntimeMethodHandle, we need a RuntimeMethodHandle for async variants. Emit the bit in the compiler, at runtime (when type loading), and read it when needed. Reflection stack should never see this RuntimeMethodHandle.
Add AsyncVariant property on MethodDesc (since runtime type system does this for unboxing methods too).
Add a flag that distinguishes async variants in native layout. This is not specific to GVMs, it also covers other cases of runtime generic dictionary building, such as MakeGenericMethod.
Add a flag that distinguishes these in generic method dictionary hashtables (both static and built at runtime)
Lots of piping through the extra bool

Cc @dotnet/ilc-contrib

* Since generic virtual method dispatch is based on `RuntimeMethodHandle`, we need a `RuntimeMethodHandle` for async variants. Emit the bit in the compiler, at runtime (when type loading), and read it when needed. Reflection stack should never see this `RuntimeMethodHandle`. * Add `AsyncVariant` property on `MethodDesc` (since runtime type system does this for unboxing methods too). * Add a flag that distinguishes async variants in native layout. This is not specific to GVMs, it also covers other cases of runtime generic dictionary building, such as `MakeGenericMethod`. * Add a flag that distinguishes these in generic method dictionary hashtables (both static and built at runtime) * Lots of piping through the extra bool

dotnet-policy-service · 2025-11-11T12:50:59Z

Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas
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Copilot

Pull Request Overview

This pull request adds support for async generic virtual methods by introducing an IsAsyncVariant flag throughout the runtime type system. The core mechanism involves emitting and reading special RuntimeMethodHandles for async variants while ensuring they remain transparent to the reflection stack.

Key Changes

Added AsyncVariant property to MethodDesc and related type system classes to track async method variants
Introduced IsAsyncVariant flag constants in multiple locations (RuntimeMethodHandle, GenericMethodsHashtable, NativeFormat MethodFlags) to distinguish async variants in data structures
Modified GVM metadata emission to skip async variants since they duplicate metadata
Updated all method resolution and instantiation code paths to thread the asyncVariant boolean parameter through

Reviewed Changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
TypeGVMEntriesNode.cs	Filters out async variants when scanning for GVM entries to avoid metadata duplication
RuntimeMethodHandleNode.cs	Stores async variant flag in the instantiation length field, retrieves actual method target for metadata
NativeLayoutVertexNode.cs	Marks methods with IsAsyncVariant flag and retrieves correct metadata token
GenericMethodsHashtableNode.cs	Encodes async variant flag in the token field of hashtable entries
RuntimeConstants.cs	Defines IsAsyncVariant constants for RuntimeMethodHandle and GenericMethodsHashtable
NativeFormat.cs	Adds IsAsyncVariant flag to MethodFlags enum
TypeSystemContext.Runtime.cs	Adds asyncVariant to method key comparison and resolution logic
RuntimeMethodDesc.cs	Implements AsyncVariant property and threads it through method resolution
RuntimeMethodDesc.Canon.cs	Passes AsyncVariant when resolving canonical method target
MethodDesc.Runtime.cs	Defines virtual AsyncVariant property with default false implementation
InstantiatedMethod.Runtime.cs	Delegates AsyncVariant property to method definition
TypeLoaderEnvironment.cs	Updates method component retrieval to include asyncVariant output parameter
TypeLoaderEnvironment.Metadata.cs	Passes isAsyncVariant: false in virtual resolve scenarios
TypeLoaderEnvironment.LdTokenResultLookup.cs	Adds async variant handling and assertion that reflection never sees async variants
TypeLoaderEnvironment.GVMResolution.cs	Threads async variant flag through GVM resolution
TypeLoaderEnvironment.ConstructedGenericMethodsLookup.cs	Decodes async variant flag from hashtable and static data, stores in method entries
TypeBuilder.cs	Stores async variant flag when registering generic method entries
NativeLayoutInfoLoadContext.cs	Reads async variant flag from native layout and passes to method resolution
GenericDictionaryCell.cs	Passes AsyncVariant when creating RuntimeMethodHandle
ExecutionEnvironmentImplementation.MappingTables.cs	Asserts async variants are not visible to reflection
RuntimeMethodHandle.cs	Restructures MethodHandleInfo to store flags packed with NumGenericArgs

…ypeSystem/InstantiatedMethod.Runtime.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

jkotas

Worth doing outer loop run or size check to validate that the async variants are not getting pulled in unexpectedly?

MichalStrehovsky · 2025-11-11T22:17:54Z

/azp run runtime-nativeaot-outerloop

azure-pipelines · 2025-11-11T22:18:13Z

Azure Pipelines successfully started running 1 pipeline(s).

MichalStrehovsky · 2025-11-11T22:20:00Z

Worth doing outer loop run or size check to validate that the async variants are not getting pulled in unexpectedly?

Triggered outerloop. rt-sz runs will be on the floor until we start producing .NET 11 bits unfortunately.

MichalStrehovsky · 2025-11-12T05:55:11Z

Worth doing outer loop run or size check to validate that the async variants are not getting pulled in unexpectedly?
Triggered outerloop. rt-sz runs will be on the floor until we start producing .NET 11 bits unfortunately.

Libs outerloop looks good. The CoreCLR test tree outerloop is on the floor, fix in #121541.

Let's not merge yet, I did a self-review and there's one more thing I want to fix.

…ect writing

MichalStrehovsky · 2025-11-12T10:19:25Z

/azp run runtime-nativeaot-outerloop

azure-pipelines · 2025-11-12T10:19:37Z

Azure Pipelines successfully started running 1 pipeline(s).

MichalStrehovsky · 2025-11-12T10:43:47Z

/azp run runtime-nativeaot-outerloop

azure-pipelines · 2025-11-12T10:43:58Z

Azure Pipelines successfully started running 1 pipeline(s).

MichalStrehovsky · 2025-11-12T21:46:21Z

/ba-g timeouts

MichalStrehovsky · 2025-11-16T13:04:18Z

Worth doing outer loop run or size check to validate that the async variants are not getting pulled in unexpectedly?

Figured out the right combination of numbers 10 and 11 that is currently needed to consume SDK builds for main.

The regression for the "reflection" test is the cost of the additional code in the type loader. The savings are from better integer compression because we dropped metadata handle.

Size statistics

Pull request #121524

Project	Size before	Size after	Difference
TodosApi-linux	24289464	24264888	-24576
TodosApi-windows	25775616	25752576	-23040
avalonia.app-linux	18833280	18816896	-16384
avalonia.app-windows	19412992	19395072	-17920
hello-linux	1139120	1139120	0
hello-minimal-linux	1003848	1003848	0
hello-minimal-windows	771584	771584	0
hello-windows	924672	924672	0
kestrel-minimal-linux	5234168	5230072	-4096
kestrel-minimal-windows	4811776	4811264	-512
reflection-linux	1808256	1812352	4096
reflection-windows	1680896	1682432	1536
webapiaot-linux	9563488	9555296	-8192
webapiaot-windows	10169856	10163712	-6144
winrt-component-minimal-windows	720896	720896	0

CopilotAI review requested due to automatic review settings November 11, 2025 12:47

MichalStrehovsky added area-NativeAOT-coreclr runtime-async labels Nov 11, 2025

dotnet-policy-serviceBot assigned MichalStrehovsky Nov 11, 2025

Copilotstarted reviewing on behalf of MichalStrehovsky November 11, 2025 12:48 View session

Copilotfinished reviewing on behalf of MichalStrehovsky November 11, 2025 12:50

CopilotAI reviewed Nov 11, 2025
View reviewed changes

Update src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/T…
ed6a8bf
…ypeSystem/InstantiatedMethod.Runtime.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

jkotas approved these changes Nov 11, 2025
View reviewed changes

Comment threadsrc/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/TypeSystem/RuntimeMethodDesc.cs
Comment thread...coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/RuntimeMethodHandleNode.cs

This was referenced Nov 11, 2025
The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008
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[android-arm64] The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#6408
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jkotas approved these changes Nov 11, 2025
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build-analysisBot mentioned this pull request Nov 12, 2025
System.IO.Tests fails with "Unexpected error code getting attributes 64 from path \\LOCALHOST" #120974
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MichalStrehovsky added 2 commits November 12, 2025 09:08

Report same dependencies during relocsOnly that we rely on during obj…
e95c4e6
…ect writing

Merge branch 'main' into gvmasync
d43f266

This was referenced Nov 12, 2025
slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883
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Android WebSocket failure #121518
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MichalStrehovsky merged commit 3927844 into dotnet:mainNov 12, 2025
100 of 119 checks passed

MichalStrehovsky deleted the gvmasync branch November 12, 2025 21:47

MichalStrehovsky mentioned this pull request Nov 12, 2025
Flow from dotnet/dotnet to aspnetcore is broken (Microsoft.Extensions.Validation.NativeAotTests) #121551
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CopilotAI mentioned this pull request Nov 13, 2025
Add ERROR_NETNAME_DELETED to IsPathUnreachableError for Windows localhost removal #121569
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[main] Source code updates from dotnet/runtime dotnet/dotnet#3329
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121524 MichalStrehovsky/rt-sz#196
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