Use shared managed thunks for reflection invocation by jkoritzinsky · Pull Request #133662 · dotnet/runtime

jkoritzinsky · 2026-09-11T03:09:01Z

Summary

Layer 1 of the stack for #123864, building on am11's #126542 and the requested split in #126542 (comment). The dependent layers are #133658 (custom attributes), #133659 (func-eval), and #133660 (dead native machinery cleanup).

Use shared, precompilable managed thunks for common MethodInfo.Invoke, ConstructorInfo.Invoke, MethodInvoker, and ConstructorInvoker shapes instead of the native reflection dispatcher.
Cover bounded reference/primitive families: ordinary reference-type instance/delegate calls, reference constructors through eight arguments, selected primitive/enum-bearing constructors and methods, and targeted static/reference-byref patterns. Comments identify the ASP.NET Core callsites motivating the specialized shapes.
Resolve virtual/interface targets for the actual receiver, and preserve declared-type argument validation, enum widths/result identity, reference copy-back, and collectible ownership.
Keep unsupported signatures on the cached emitted fallback; this does not add general struct/nullable/value-type-receiver support.
Stay shared for the first 10,000 calls, then specialize starting on call 10,001. Promotion and every specialization strategy require RuntimeFeature.IsDynamicCodeCompiled, not merely IsDynamicCodeSupported.
Preserve existing-object constructor invocation and make ReadyToRun's explicit-this calli rewrite agree with the VM intrinsic.

No public API is added.

Validation

The threshold update passed 1,964 reflection + 631 forced-emitted + 631 forced-shared cases on Windows x64 Checked CoreCLR. Exact boundary tests cover the object, span, and byref strategies; the old 100-call runtime fails those tests as expected. A controlled CoreLib configuration with dynamic code supported but not compiled passed another 631 + 631 forced-mode cases and retained shared invocation beyond 10,000 calls. That configuration is policy coverage, not a claim of executing a native compiler-less platform.

The bounded matrix includes virtual/interface/generic-virtual/default-interface dispatch, delegate DynamicInvoke with static and multicast callbacks, enum widths/results, reference out-parameter success/false/exception behavior, moving GC, unsupported-shape boundaries, and collectible methods. Later stack validation also executed the invocation suites on Windows x86. Browser/WASI managed CoreLib/ABI generation was checked; actual browser/WASI and big-endian runtime execution was not performed.

Performance evidence

Local measurements used a Windows x64 EPYC 7763 Hyper-V VM. The ASP.NET Core survey at dotnet/aspnetcore revision a2ac63c3a56d establishes source-level invocation demand, not measured performance rankings.

Adding the bounded families avoided approximately 1.5–5 KiB of managed allocation per first invocation versus the earlier stack's emitted fallback. An actual ASP.NET Core 10.0.9 UseMiddleware/ActivatorUtilities eight-reference-constructor startup probe measured median 16.8753 → 14.4399 ms and 9,560 → 5,376 bytes across seven paired fresh-process runs. This did not measure ordinary compiled request dispatch or default-constructor Activator paths.

For the separate 100 → 10,000 threshold comparison, matching Release native hosts and baseline/changed CoreLib were run with ReadyToRun disabled for both. Seventy-two fresh-process observations confirmed the actual boundary. Selected warmed BenchmarkDotNet results were:

Shape	Threshold 100	Threshold 10,000	Managed allocation
Eight-reference constructor	252.30 ns	228.15 ns	24 B in both
Instance primitive getter	26.57 ns	25.25 ns	24 B in both
Static four-reference method	115.95 ns	94.97 ns	0 B in both

These are short VM-local measurements, not universal throughput guarantees. Earlier expanded-shape testing at threshold 100 exposed a profile-sensitive warmed ConstructorInfo.Invoke eight-argument case at approximately 1.30× baseline; tiering-disabled/direct-loop controls and the actual ConstructorInvoker middleware API did not reproduce that effect. The threshold comparison above is a separate experiment.

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Note

This PR description and implementation were prepared with GitHub Copilot. Commits that reuse am11's code retain the requested co-author attribution.

azure-pipelines · 2026-09-11T03:09:44Z

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dotnet-policy-service · 2026-09-11T03:11:05Z

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azure-pipelines · 2026-09-15T18:58:13Z

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Copilot

Copilot review overview

🟡 Changes recommended

Three unresolved findings affect constructor initialization, unmanaged-only/P/Invoke handling, and existing-instance constructor IL.

Get a fresh assessment by requesting another Copilot review.

Review tier: Lite
Findings: 2

Open (2)

Exclude unmanaged entrypoints from managed shared calli · New
Existing constructor calls fall through into the allocation path · New

What changed in this PR

This PR routes selected reflection invocation paths through shared managed thunks while retaining emitted fallbacks and specialization.

Changes:

Adds bounded shared method and constructor thunk families with 10,000-call promotion.
Updates virtual dispatch, constructor handling, calli integration, and CoreCLR/ReadyToRun support.
Expands reflection and boundary tests; no public API is added.

File	Reviewed change
`src/libraries/System.Runtime/tests/System.Reflection.Tests/MethodInvokerTests.cs`	Tests method thunk promotion, dispatch, and boundaries.
`src/libraries/System.Runtime/tests/System.Reflection.Tests/ConstructorInvokerTests.cs`	Tests constructor promotion and existing-instance scenarios.
`src/libraries/System.Runtime/tests/System.Reflection.Tests/ConstructorInfoTests.cs`	Tests constructor shapes, semantics, and fallback behavior.
`src/libraries/System.Private.CoreLib/src/System/Reflection/MethodInvokerCommon.cs`	Updates common invocation strategy and caching.
`src/libraries/System.Private.CoreLib/src/System/Reflection/MethodInvoker.cs`	Routes managed method invocation through shared thunks.
`src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.Constructor.cs`	Integrates constructor invocation state and strategy selection.
`src/libraries/System.Private.CoreLib/src/System/Reflection/InvokerEmitUtil.cs`	Updates emitted fallback generation; existing-instance constructor IL has an inconsistent stack path (critical).
`src/coreclr/vm/runtimehandles.h`	Declares receiver-specific target resolution support.
`src/coreclr/vm/runtimehandles.cpp`	Implements receiver-specific virtual target resolution.
`src/coreclr/vm/reflectioninvocation.cpp`	Updates native reflection invocation integration.
`src/coreclr/vm/qcallentrypoints.cpp`	Registers the new QCall entrypoint.
`src/coreclr/vm/corelib.h`	Registers the CoreLib helper type.
`src/coreclr/vm/callingconvention.h`	Updates calling-convention support.
`src/coreclr/vm/appdomain.cpp`	Updates reflection helper registration.
`src/coreclr/tools/Common/CallingConvention/ArgIterator.cs`	Updates calling-convention argument iteration support.
`src/coreclr/tools/aot/ILCompiler.ReadyToRun/IL/Stubs/InstanceCalliHelperIntrinsics.cs`	Rewrites explicit-this calli signatures.
`src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/InstanceCalliHelperTests.cs`	Tests ReadyToRun calli rewriting.
`src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj`	Includes CoreCLR thunk sources.
`src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs`	Declares managed virtual-target resolution support.
`src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodInvoker.CoreCLR.cs`	Routes CoreCLR method invocation through shared thunks.
`src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs`	Integrates CoreCLR invocation state.
`src/coreclr/System.Private.CoreLib/src/System/Reflection/IntrinsicInvokeHelper.cs`	Classifies and dispatches shared thunks; constructor initialization and unmanaged-only/P/Invoke handling require changes (moderate, critical).
`src/coreclr/System.Private.CoreLib/src/System/Reflection/InstanceCalliHelper.cs`	Adds explicit-this calli helpers.
`src/coreclr/System.Private.CoreLib/src/System/Reflection/ConstructorInvoker.CoreCLR.cs`	Routes CoreCLR constructor invocation through shared thunks.
`src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/MethodInvoker.cs`	Maintains the NativeAOT method invoker implementation.

Copilot

Copilot review overview

🟡 Changes recommended

Shared calli paths can bypass required type initialization, and forced-emitted mode currently selects shared thunks.

Get a fresh assessment by requesting another Copilot review.

Review tier: Lite
Findings: 3

Open (3)

Preserve type initialization before shared calli invocation · New
Run the type initializer before invoking shared constructors · New
Existing constructor calls fall through into the allocation path

Resolved since last review (1)

Exclude unmanaged entrypoints from managed shared calli

Avoid emitting direct existing-instance constructor calls for string and array constructors. Keep those special constructor forms on the allocation-style emitted path so reflection invoke does not call VM special constructors as ordinary instance entrypoints. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Keep string and array existing-instance constructor invocation on the no-op constructor result path while avoiding direct emitted calls to their special VM constructor entrypoints. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

- RuntimeMethodHandle_GetVirtualFunctionPointer now calls PrepareForUseAsAFunctionPointer() after EnsureActive() before resolving the virtual target, matching RuntimeMethodHandle_GetFunctionPointer's contract that value-type parameters be loaded before a raw entrypoint is handed out for a managed calli. - Fix "constuctor" -> "constructor" typo in a comment. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

… caching invoker AssertPromoted(MethodBase) and AssertNotPromoted(MethodBase, int) called GetCachedInvoker(method) directly as part of evaluating the argument expression, before the ShouldAssertSharedSelection guard (which requires PlatformDetection.IsCoreCLR) could short-circuit — unlike the sibling AssertShared(MethodBase)/AssertFallback(MethodBase) overloads, which check the flag first. On Mono (all failing System.Reflection.Tests / InvokeEmit.Tests / InvokeInterpreted.Tests WASM CI legs run on Mono), RuntimeMethodInfo has no CoreCLR-only "m_invoker" cached-invoker field, so GetCachedInvoker's Assert.NotNull failed immediately regardless of platform. No product code changes; this only affects test-helper gating. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

…ng-type checks TryGetShape's P/Invoke and [UnmanagedCallersOnly] exclusions were unnecessary: the shared-calli path resolves the same stable entry point as the emitted-invoker path (MethodDesc::GetMultiCallableAddrOfCode), so a P/Invoke target dispatches correctly through either path, and an UnmanagedCallersOnly target fails identically in both (the reverse-P/Invoke check lives at the callee's entry point, not in the caller). Also removes the redundant declaringType.ContainsGenericParameters check on constructors: method.ContainsGenericParameters, checked earlier in the same method, already covers the declaring type for constructors. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

The test covers CoreCLR's handling of string and array pseudo-constructors. Those constructors are not uniformly reflectable on Mono and NativeAOT targets, where this CoreCLR-specific behavior is not implemented. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Keep the shared invocation strategy while matching the previous reflection dispatcher's results for pseudo-constructors invoked with a target. String constructors remain a no-op that returns null; array constructors throw the same InvalidProgramException that reflection wraps in TargetInvocationException. Split the regression coverage so each distinct baseline contract is explicit. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

jkotas · 2026-09-30T20:43:35Z

+            internal int InvocationCount;
+            internal int SpecializationThreshold;


We can merge these two to a single int that counts down to zero.

jkotas · 2026-09-30T20:45:18Z

+
+                if (RuntimeFeature.IsDynamicCodeCompiled &&
+                    !(LocalAppContextSwitches.ForceInterpretedInvoke && !LocalAppContextSwitches.ForceEmitInvoke) &&
+                    Interlocked.Increment(ref state.InvocationCount) >= state.SpecializationThreshold)


This can be a regular increment instead of Interlocked.Increment to reduce contention. It is ok if we some increments get dropped.

jkotas · 2026-09-30T20:55:05Z

+        {
+            unsafe
+            {
+                if (!method.IsStatic && obj is not null && obj.GetType().IsValueType)


Why do we need to special case this here?

jkotas · 2026-09-30T21:00:46Z

+                    target = RuntimeMethodHandle.GetVirtualFunctionPointer((RuntimeMethodInfo)method, obj!);
+                }
+
+                object? result = thunk(target, obj, args, method.DeclaringType);


method.DeclaringType is a virtual call. Can we cache the declaring type in the state (for the ctor case where it matters)?

We can store it as RuntimeType and then call RuntimeType.GetUninitializedObject() to avoid some more overhead.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

jkotas · 2026-09-30T22:37:23Z

+        pMethod->EnsureActive();
+        pMethod->PrepareForUseAsAFunctionPointer();


Suggested change

pMethod->EnsureActive();

pMethod->PrepareForUseAsAFunctionPointer();

jkotas · 2026-09-30T23:52:40Z

+                }
+
+                if (RuntimeFeature.IsDynamicCodeCompiled &&
+                    !(LocalAppContextSwitches.ForceInterpretedInvoke && !LocalAppContextSwitches.ForceEmitInvoke) &&


Can ForceEmitInvoke ever be true here?

github-actions Bot added the area-System.Reflection label Sep 11, 2026

dotnet-policy-service Bot assigned jkoritzinsky Sep 11, 2026

github-project-automation Bot added this to AppModel Sep 11, 2026

jkoritzinsky changed the title ~~dev/jkoritzinsky/custom attribute stack~~ Use shared managed thunks for reflection invocation Sep 11, 2026

jkoritzinsky added this pull request to stack #133663 September 11, 2026 03:11

jkoritzinsky mentioned this pull request Sep 11, 2026

Integrate value-class GC protection into GCFrame across CoreCLR and NativeAOT #133730

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jkotas reviewed Sep 14, 2026

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Comment thread src/libraries/System.Runtime/tests/System.Reflection.Tests/default.rd.xml Outdated

jkoritzinsky force-pushed the dev/jkoritzinsky/custom-attribute-stack branch from c3f6c6f to 12bb7ac Compare September 15, 2026 00:28

build-analysis Bot mentioned this pull request Sep 15, 2026

Runtime_133587 SIGSEGV in mono #133910

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jkoritzinsky marked this pull request as ready for review September 15, 2026 18:57

Copilot AI lite review requested due to automatic review settings September 15, 2026 18:57

jkoritzinsky requested a review from MichalStrehovsky as a code owner September 15, 2026 18:57

jkoritzinsky requested review from davidwrighton and jkotas September 15, 2026 18:57

Copilot started reviewing on behalf of jkoritzinsky September 15, 2026 18:58 View session

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Comment thread src/coreclr/System.Private.CoreLib/src/System/Reflection/IntrinsicInvokeHelper.cs

Comment thread src/libraries/System.Private.CoreLib/src/System/Reflection/InvokerEmitUtil.cs

Copilot AI review requested due to automatic review settings September 15, 2026 22:52

Copilot started reviewing on behalf of jkoritzinsky September 15, 2026 22:53 View session

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Comment thread src/coreclr/System.Private.CoreLib/src/System/Reflection/IntrinsicInvokeHelper.cs

Comment thread src/coreclr/System.Private.CoreLib/src/System/Reflection/IntrinsicInvokeHelper.cs Outdated

jkoritzinsky and others added 13 commits September 29, 2026 13:32

Reword the comment and add some asserts

69d2b3e

Reject special constructors with existing targets

31c95ac

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Use closed generic types in reflection tests

c17608b

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Use closed generic methods in reflection tests

de41b5d

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Allow invoking abstract constructors on existing instances

d13221a

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Fix abstract constructor invocation across invoker paths

74aaea3

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

jkotas reviewed Sep 29, 2026

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Comment thread src/libraries/System.Runtime/tests/System.Reflection.Tests/MethodInvokerTests.cs Outdated

jkotas reviewed Sep 29, 2026

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Comment thread src/libraries/System.Runtime/tests/System.Reflection.Tests/MethodInfoTests.cs

jkotas reviewed Sep 29, 2026

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Comment thread src/coreclr/vm/runtimehandles.cpp

jkoritzinsky force-pushed the dev/jkoritzinsky/custom-attribute-stack branch from 27b55e5 to 74aaea3 Compare September 29, 2026 21:31

jkoritzinsky and others added 3 commits September 29, 2026 15:37

Prepare resolved virtual targets

b197594

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Track unsupported reflection tests

747d1c5

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Correct reflection issue mappings

73b65c2

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

build-analysis Bot mentioned this pull request Sep 30, 2026

HttpMetricsTest_Http20.TimeInQueue_RecordedForNewConnectionsOnly test failure #122522

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jkotas reviewed Sep 30, 2026

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Comment thread src/coreclr/vm/method.cpp Outdated

jkotas reviewed Sep 30, 2026

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Comment thread src/coreclr/vm/method.cpp Outdated

jkotas reviewed Sep 30, 2026

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Simplify virtual target preparation

faf1850

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

jkotas reviewed Sep 30, 2026

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		internal int InvocationCount;
		internal int SpecializationThreshold;

		pMethod->EnsureActive();
		pMethod->PrepareForUseAsAFunctionPointer();

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