Trim netcoreapp libraries against implementations by am11 · Pull Request #136495 · dotnet/runtime

am11 · 2026-10-27T00:06:31Z

Generic version of @#136476.

Library	`main`	Branch	Diff
System.ComponentModel.TypeConverter	308,224	307,712	−512
System.Diagnostics.Process	158,720	158,208	−512
System.Formats.Tar	106,496	105,984	−512
System.IO.Compression	189,440	188,416	−1,024
System.IO.FileSystem.DriveInfo	38,912	38,400	−512
System.Linq.Parallel	215,552	215,040	−512
System.Net.Http	579,584	579,072	−512
System.Net.NameResolution	93,184	92,672	−512
System.Net.Ping	41,984	41,472	−512
System.Net.Quic	154,624	150,528	−4,096
System.Net.Security	371,200	370,176	−1,024
System.Net.Sockets	211,968	208,384	−3,584
System.Runtime.InteropServices	54,784	53,248	−1,536
System.Runtime.Numerics	208,896	203,264	−5,632
System.Security.Cryptography	1,129,472	1,125,376	−4,096
System.Text.RegularExpressions	384,512	384,000	−512
System.Threading.Tasks.Parallel	48,640	48,128	−512
Total (all DLLs)	33,018,368	32,992,256	−26,112

azure-pipelines · 2026-10-27T00:07:16Z

Azure Pipelines: Successfully started running 3 pipeline(s). 13 pipeline(s) were filtered out due to trigger conditions. There may be pipelines that require an authorized user to comment /azp run to run.

dotnet-policy-service · 2026-10-27T00:07:52Z

Tagging subscribers to this area: @agocke, @dotnet/illink
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am11 · 2026-10-27T12:59:10Z

@jkotas, @agocke, this generic approach is more profitable compared to #136476, but comes with bit of a noise. It skips over AppContext switches.

jkotas · 2026-10-28T23:48:50Z

@sbomer Could you please take a look?

# Conflicts: # src/coreclr/vm/wasm/wasi/callhelpers-pinvoke.cpp

sbomer

Do we need to somehow prevent baking in constants from an OOB library that might change across versions?

- Use the reference assembly of packable libraries, which can be replaced by a newer package at run time. - Trim after CoreCompile with the implementation references as inputs, so changes to them are picked up incrementally. - Don't disable the optimization when BuildAllConfigurations is set, which -pack sets for shipping builds. - Allow --ignore-substitutions in the cacheable ILLink task arguments. - Make not updating reference scopes the default in library mode instead of a new option.

am11 · 2026-10-29T20:37:12Z

Do we need to somehow prevent baking in constants from an OOB library that might change across versions?

Packable libraries now contribute their reference assembly instead of the implementation.

- Don't trim packable libraries against implementations, as their assets run on any OS. - Build the best flavor separately so that its implementation isn't added to the closure.

sbomer

LGTM, thank you!

Copilot

🟡 Changes recommended

Disabling scope rewriting for all library-mode runs can leave broken references when dependency sweeping removes a required facade or forwarder.

2 open issues

What changed in this PR

This PR generalizes the OS-check trimming approach from #136476 by trimming shared-framework libraries against implementation assemblies, enabling more constant propagation and reporting a 25,088-byte reduction across DLLs.

Changes:

Resolves target-OS implementation dependencies and reruns trimming when those inputs change.
Preserves original reference scopes and prevents library builds from folding unset feature switches.
Updates cache-argument handling, adds task tests, and removes unused WASI interop entries and thunks.

File	Description
`src/tools/illink/test/ILLink.Tasks.Tests/ILLink.Tasks.Tests.cs`	Tests cache-key handling of substitution options.
`src/tools/illink/src/linker/Linker/MemberActionStore.cs`	Detects feature-switch getters without explicit settings.
`src/tools/illink/src/linker/Linker/LinkContext.cs`	Tracks library roots and reference-scope policy.
`src/tools/illink/src/linker/Linker.Steps/UnreachableBlocksOptimizer.cs`	Prevents folding unset feature switches in library mode.
`src/tools/illink/src/linker/Linker.Steps/SweepStep.cs`	Supports retaining original assembly reference scopes.
`src/tools/illink/src/linker/Linker.Steps/RootAssemblyInputStep.cs`	Enables scope preservation for library roots.
`src/tools/illink/src/ILLink.Tasks/LinkTask.cs`	Allows substitution options in cacheable arguments.
`src/coreclr/vm/wasm/wasi/callhelpers-pinvoke.cpp`	Removes unused native entries and updates consumer comments.
`src/coreclr/vm/wasm/wasi/callhelpers-interp-to-managed.cpp`	Removes two unused call-helper signatures.
`eng/illink.targets`	Resolves implementation dependencies and coordinates incremental trimming.

_{Review effort: Balanced}

jkotas · 2026-11-07T04:34:59Z

"The checked-in CoreCLR WebAssembly call helpers" build failure looks related to the changes in the PR

jkotas · 2026-11-07T16:58:16Z

ILLink tests failing

Expected the assembly impl.dll to not exist in /__w/1/s/artifacts/bin/ILLink.testcases/linker_tests/Libraries/LibraryModeFeatureSwitchConstants/output, but it did

am11 · 2026-11-07T18:20:00Z

@jkotas that failure was ILTrim (CLR_Tools_Tests) reusing the Mono.Linker case — ILTrim doesn't fold trivial feature-switch constants yet, so the case is on ILTrimExpectedFailures and skips there. illink's LibraryModeFeatureSwitchConstants still runs and passes.

jkotas · 2026-11-07T19:22:02Z

@sbomer Could you please do another review (additional changes made since your signoff)?

A feature switch with a constant body can still be substituted at application publish time. Instead, pass IsMultithreadingSupported=false explicitly for the single-threaded browser and wasi flavors, and allow --feature in the cacheable ILLink arguments. Co-authored-by: Cursor <cursoragent@cursor.com>

am11 · 2026-11-12T00:18:24Z

Wasi failure is unrelated (infra issue).

sbomer · 2026-11-12T00:28:44Z

/ba-g "deadletter"

am11 requested a review from sbomer as a code owner October 27, 2026 00:06

github-actions Bot added the area-Tools-ILLink .NET linker development as well as trimming analyzers label Oct 27, 2026

dotnet-policy-service Bot added linkable-framework Issues associated with delivering a linker friendly framework community-contribution Indicates that the PR has been added by a community member labels Oct 27, 2026

am11 mentioned this pull request Oct 27, 2026

Trim OperatingSystem.IsXxx checks in library build #136476

Closed

Trim netcoreapp libraries against implementations

78656c1

am11 force-pushed the illink-impl-references branch from 63ecb76 to 78656c1 Compare October 27, 2026 00:44

build-analysis Bot mentioned this pull request Oct 27, 2026

[ci-scan] Test failure: System.Numerics.Tensors.Tests.TensorTests.TensorValueReductionsPreserveScalarOrder #136367

Closed

am11 requested a review from jkotas October 28, 2026 23:45

Merge remote-tracking branch 'dotnet/main' into illink-impl-references

1db83d6

# Conflicts: # src/coreclr/vm/wasm/wasi/callhelpers-pinvoke.cpp

build-analysis Bot mentioned this pull request Oct 29, 2026

Test failure: BeginReceiveFrom_RemoteEpIsReturnedWhenCompletedSynchronously #134885

Open

Merge remote-tracking branch 'dotnet/main' into illink-impl-references

ae5bdc6

sbomer reviewed Oct 29, 2026

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Comment thread eng/illink.targets Resolved

Comment thread eng/illink.targets Resolved

Comment thread eng/illink.targets Resolved

Comment thread src/tools/illink/src/linker/Linker/Driver.cs Resolved

am11 added 2 commits October 29, 2026 22:33

Merge remote-tracking branch 'dotnet/main' into HEAD

3f3c51c

This was referenced Oct 30, 2026

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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The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

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am11 requested a review from sbomer October 30, 2026 18:23

sbomer reviewed Nov 5, 2026

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Comment thread eng/illink.targets Resolved

Comment thread eng/illink.targets Resolved

am11 added 2 commits November 6, 2026 13:36

Only use reference assemblies of packable libraries

0eece91

- Don't trim packable libraries against implementations, as their assets run on any OS. - Build the best flavor separately so that its implementation isn't added to the closure.

Merge remote-tracking branch 'dotnet/main' into HEAD

290e2c8

sbomer approved these changes Nov 6, 2026

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jkotas requested a balanced review from Copilot November 6, 2026 21:44

Copilot started reviewing on behalf of jkotas November 6, 2026 21:44

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Copilot AI reviewed Nov 6, 2026

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Comment thread src/tools/illink/src/linker/Linker.Steps/RootAssemblyInputStep.cs Resolved

Comment thread src/tools/illink/src/linker/Linker.Steps/UnreachableBlocksOptimizer.cs Resolved

build-analysis Bot mentioned this pull request Nov 7, 2026

[ci-scan] Test failure: System.Net.Http.Functional.Tests.SocketsHttpHandler_HttpClientHandler_ClientCertificates_Test.Android_GetCertificateFromKeyStoreViaAlias #136641

Open

jkotas reviewed Nov 7, 2026

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Comment thread src/coreclr/vm/wasm/browser/callhelpers-pinvoke.cpp Resolved

jkotas requested a review from sbomer November 7, 2026 19:20

am11 force-pushed the illink-impl-references branch from 33bdabc to 26dfdb5 Compare November 7, 2026 19:47

am11 added 2 commits November 7, 2026 21:49

Address CR feedback

5c1044d

Merge dotnet/main into illink-impl-references

aad7305

am11 force-pushed the illink-impl-references branch from 26dfdb5 to aad7305 Compare November 7, 2026 19:49

sbomer reviewed Nov 10, 2026

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Comment thread src/tools/illink/src/linker/Linker.Steps/UnreachableBlocksOptimizer.cs Resolved

am11 and others added 2 commits November 10, 2026 14:38

Merge branch 'main' into illink-impl-references

6690f19

sbomer approved these changes Nov 10, 2026

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sbomer mentioned this pull request Nov 10, 2026

Treat multithreading support as an immutable runtime capability #137285

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am11 requested a review from jkotas November 11, 2026 16:32

sbomer merged commit f4775e5 into dotnet:main Nov 12, 2026
156 of 159 checks passed

am11 deleted the illink-impl-references branch November 12, 2026 00:36

am11 mentioned this pull request Nov 12, 2026

Make some lib projects platform-agnostic #132218

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dotnet-maestro Bot mentioned this pull request Nov 12, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#10937

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dotnet-milestone-bot Bot added this to the 12.0-preview1 milestone Nov 12, 2026

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