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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Copilot

Copilot review overview

🟡 Changes recommended

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

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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

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

Copilot

Copilot review overview

🟡 Changes recommended

Unresolved correctness and fallback issues affect generic constructors, existing-instance array/string constructors, and thunk promotion behavior.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 2

Open (2)

Exclude shared generic declaring types from constructor thunks · New
Do not emit a call for special constructors · New

Resolved since last review (3)

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

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>

Copilot

Copilot review overview

🟡 Changes recommended

Critical virtual function-pointer preparation and moderate dynamic-code fallback issues remain unresolved.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 1 · 1

Open (2)

Prepare virtual entrypoints before managed calli · New
Correct the spelling in the constructor comment · New

Resolved since last review (2)

Do not emit a call for special constructors
Exclude shared generic declaring types from constructor thunks

- 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>

Copilot

Copilot review overview

🟡 Changes recommended

A critical compiler-less CoreCLR fallback issue and moderate constructor initialization coverage gap remain.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 1

Open (1)

Fallback still emits when dynamic code is not compiled · New

Resolved since last review (2)

Prepare virtual entrypoints before managed calli
Correct the spelling in the constructor comment

jkotas · 2026-09-18T03:25:18Z

Test failures related to the PR

jkotas · 2026-09-18T03:58:57Z

@EgorBot --filter "System.Reflection.Invoke.*"

jkotas · 2026-09-18T04:12:33Z

+                    method.ContainsGenericParameters ||
+                    (method.CallingConvention & CallingConventions.VarArgs) != 0 ||
+                    (method.Attributes & MethodAttributes.PinvokeImpl) != 0 ||
+                    method.IsDefined(typeof(UnmanagedCallersOnlyAttribute), inherit: false))


What is not going to work when we delete (method.Attributes & MethodAttributes.PinvokeImpl) != 0 and method.IsDefined(typeof(UnmanagedCallersOnlyAttribute), inherit: false checks here?

I do not think the failure modes are any different between the emit path and the precompiled path if we delete these checks. There may be some asserts in checked build - but that's by design for invalid unsafe interop code.

I would expect PInvoke to just work; and UnmanagedCallersOnlyAttribute to crash with "Invalid Program: attempted to call a UnmanagedCallersOnly method from managed code."

jkotas · 2026-09-18T04:25:14Z

+                        !IsReferenceType(declaringType) ||
+                        declaringType.IsAbstract ||
+                        declaringType.IsArray ||
+                        declaringType.ContainsGenericParameters ||


This should not be needed - we have checked method.ContainsGenericParameters above.

… 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>

Copilot

Copilot review overview

🟡 Changes recommended

Unresolved constructor initialization, constructor validation, and UnmanagedCallersOnly handling issues block approval.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 1

Open (1)

Preserve class initialization when allocating shared constructors · New

Resolved since last review (1)

Fallback still emits when dynamic code is not compiled

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

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

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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

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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

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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

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jkoritzinsky force-pushed the dev/jkoritzinsky/custom-attribute-stack branch from b9b2c27 to 95ec713 Compare September 16, 2026 22:59

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Remove InstanceCalliHelper tests

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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

This was referenced Sep 17, 2026

[wasm] OpenQA.Selenium.WebDriverTimeoutException: timeout: Timed out receiving message from renderer #117486

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System.Net.Quic.QuicException : Connection handshake was canceled due to the configured timeout #133645

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jkoritzinsky and others added 3 commits September 17, 2026 11:09

Reword the comment and add some asserts

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

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Test failure: GC/Features/HeapExpansion/bestfit-finalize/bestfit-finalize.cmd #132107

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XHarness package install failure on iOS due to devicectl NSPOSIXErrorDomain error 49 #123796

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EgorBot mentioned this pull request Sep 18, 2026

Benchmarks for dotnet/runtime#133662 (for @jkotas) EgorBot/Benchmarks#601

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EgorBot mentioned this pull request Sep 18, 2026

Benchmarks for dotnet/runtime#133662 (for @jkotas) EgorBot/Benchmarks#602

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build-analysis Bot mentioned this pull request Sep 18, 2026

[ci-scan] Test failure: HandleEventShutdownInitiatedByTransport fails with QuicException : The connection timed out from inactivity. #133373

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jkoritzinsky commented Sep 11, 2026 •

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