Decouple ILC from ManagedAssemblyToLink by Copilot · Pull Request #124801 · dotnet/runtime

Copilot · 2026-02-24T16:58:36Z

_ComputeManagedAssemblyForILLink in NativeAOT was indirectly dependent on ComputeIlcCompileInputs via @(ManagedBinary), which made PrepareForILLink ordering-sensitive and broke incremental ILLink behavior when ILLink is run before ILC input computation. This change removes that coupling so ILLink preparation no longer relies on ComputeIlcCompileInputs side effects.

What changed
- Updated src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets in _ComputeManagedAssemblyForILLink.
- Replaced @(ManagedBinary) with @(IntermediateAssembly) when reconstructing @(ManagedAssemblyToLink).
Why this matters
- @(IntermediateAssembly) is available during PrepareForILLink, independent of ComputeIlcCompileInputs.
- This preserves inclusion of the project assembly in @(ManagedAssemblyToLink) regardless of whether ComputeIlcCompileInputs runs before or after PrepareForILLink/ILLink.

Code change

<ManagedAssemblyToLink Include="@(DefaultFrameworkAssemblies);@(_ManagedResolvedAssembliesToPublish);@(IntermediateAssembly)" />

Original prompt

This section details on the original issue you should resolve

<issue_title>ComputeIlcCompileInputs should not need to run before PrepareForILLink</issue_title>
<issue_description>## Description

The default IlcCompileDependsOn in Microsoft.NETCore.Native.targets orders ComputeIlcCompileInputs before PrepareForILLink:
Compile;ComputeIlcCompileInputs;SetupOSSpecificProps;PrepareForILLink
This couples ILC's input computation to ILLink's preparation phase. _ComputeManagedAssemblyForILLink (which runs AfterTargets="_ComputeManagedAssemblyToLink" during PrepareForILLink) consumes @(ManagedBinary), a side effect of ComputeIlcCompileInputs. This ordering works for the standard pipeline because it doesn't actually run ILLink (RunILLink=false), but it breaks consumers that need PrepareForILLink and ILLink to run before ComputeIlcCompileInputs.

Why a consumer would need the opposite order

The standard NativeAOT pipeline sets RunILLink=false — ILLink never actually runs, and @(ManagedAssemblyToLink) is only used as metadata for ILC. A consumer that sets RunILLink=true to actually trim assemblies before ILC needs ILLink to complete first, so that ILC consumes the trimmed output. This requires PrepareForILLink and ILLink to precede ComputeIlcCompileInputs — the opposite of the default order. This is the case in .NET for Android's NativeAOT pipeline.

Impact

When PrepareForILLink runs before ComputeIlcCompileInputs, _ComputeManagedAssemblyForILLink builds its replacement @(ManagedAssemblyToLink) list before @(ManagedBinary) has been populated. The project assembly ends up missing from @(ManagedAssemblyToLink), which is used as Inputs by _RunILLink (in Microsoft.NET.ILLink.targets). This causes ILLink's incremental build check to miss changes to the project assembly, so ILLink skips on rebuild even though the assembly changed.

First builds still succeed because PrepareForILLink independently adds @(IntermediateAssembly) as a TrimmerRootAssembly, so ILLink loads and processes it regardless. Only incremental builds are affected.

Reproduction

Create a dotnet new console project with the following csproj (note: explicit SDK imports are needed because Microsoft.NETCore.Native.targets unconditionally sets RunILLink=false, so it must be overridden after the SDK targets load):
<Project>
  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk" />

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net11.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <PublishAot>true</PublishAot>
    <RuntimeIdentifier>linux-x64</RuntimeIdentifier>
  </PropertyGroup>

  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />

  <PropertyGroup>
    <RunILLink>true</RunILLink>
    <IlcCompileDependsOn>
      Compile;
      SetupOSSpecificProps;
      PrepareForILLink;
      ILLink;
      ComputeIlcCompileInputs
    </IlcCompileDependsOn>
  </PropertyGroup>
</Project>
Run dotnet publish, then change "Hello, World!" to "Hello, Changed!" in Program.cs and publish again. On the second publish, ILLink is skipped (no "Optimizing assemblies for size" message) and the trimmed assembly in obj/.../linked/ReproApp.dll still contains Hello, World!.

Suggestion

Decouple ComputeIlcCompileInputs from PrepareForILLink so neither depends on having run before the other. Ideally _ComputeManagedAssemblyForILLink should not rely on state produced by ComputeIlcCompileInputs, and ComputeIlcCompileInputs should be free to run after ILLink without breaking the ILLink preparation phase.

Workaround

.NET for Android can work around this by injecting @(IntermediateAssembly) into @(ManagedAssemblyToLink) after _ComputeManagedAssemblyForILLink replaces it:
<Target Name="_AndroidFixManagedAssemblyToLink"
    AfterTargets="_ComputeManagedAssemblyForILLink">
  <ItemGroup>
    <ManagedAssemblyToLink Include="@(IntermediateAssembly)" />
  </ItemGroup>
</Target>
```</issue_description>

<agent_instructions>Decouple these targets. The ILC inputs should not be resolved from ManagedAssemblyToLink.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

Fixes ComputeIlcCompileInputs should not need to run before PrepareForILLink #124800

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

…puts Co-authored-by: sbomer <787361+sbomer@users.noreply.github.com>

…lyToLink Factor _PrepareTrimConfiguration out of PrepareForILLink so shared trim configuration operates on ResolvedFileToPublish and flows to both ILLink and ILC without duplication. For NativeAOT, _ComputeAssembliesToCompileToNative replaces CoreCLR runtime pack files with DefaultFrameworkAssemblies (tagged PostprocessAssembly=true) before _PrepareTrimConfiguration runs. _ComputeIlcCompileInputs then derives IlcReference from ResolvedFileToPublish via PostprocessAssembly metadata, ensuring ILC sees ILLink-relocated paths when both run. ComputeLinkedFilesToPublish hooks AfterTargets=ILLink (instead of ComputeResolvedFilesToPublishList) for correct ordering when both ILLink and ILC run. RunILLink is made conditional so projects can opt in. Remove ManagedAssemblies output from the C# task (replaced by ResolvedFileToPublish filtering). Add RuntimePackFilesToSkipPublish output for early removal of CoreCLR runtime pack files. Fix OOB assembly handling so overrides stay in ResolvedFileToPublish.

Skip _ComputeIlcCompileInputs for framework library builds (BuildingFrameworkLibrary=true) since they use BuildOneFrameworkLibrary for input computation, not the publish-pipeline targets.

When NativeCompilationDuringPublish is false (e.g. Apple non-library-mode builds), Publish.targets is not imported so _ComputeIlcCompileInputs does not exist to populate IlcReference from ResolvedFileToPublish. Fall back to DefaultFrameworkAssemblies directly in ComputeIlcCompileInputs so ILC can find System.Private.CoreLib and other framework references.

sbomer · 2026-03-02T03:00:15Z

/azp list

azure-pipelines · 2026-03-02T03:00:27Z

CI/CD Pipelines for this repository: runtime-coreclr outerloop runtime-coreclr jitstress runtime-coreclr jitstressregs runtime-coreclr jitstress2-jitstressregs runtime-coreclr gcstress0x3-gcstress0xc runtime-coreclr gcstress-extra runtime-coreclr r2r-extra runtime-coreclr jitstress-isas-x86 runtime-coreclr jitstress-isas-arm runtime-coreclr jitstressregs-x86 runtime-coreclr libraries-jitstressregs runtime-coreclr libraries-jitstress2-jitstressregs runtime-coreclr r2r runtime-coreclr runincontext runtime-coreclr crossgen2 runtime-libraries-coreclr outerloop runtime-libraries-coreclr outerloop-windows runtime-libraries-coreclr outerloop-linux runtime-libraries-coreclr outerloop-osx runtime runtime-libraries enterprise-linux runtime-libraries stress-http runtime-libraries stress-ssl runtime-dev-innerloop runtime-coreclr crossgen2 outerloop coreclr-release-outerloop-nightly runtime-coreclr crossgen2-composite runtime-jit-experimental runtime-coreclr libraries-jitstress dotnet-linker-tests runtime-coreclr ilasm runtime-coreclr crossgen2-composite gcstress runtime-coreclr pgo runtime-coreclr libraries-pgo Antigen runtime-community Fuzzlyn runtime-coreclr superpmi-replay runtime-wasm runtime-coreclr superpmi-diffs runtime-coreclr superpmi-asmdiffs-checked-release runtime-extra-platforms jit-cfg runtime-wasm-perf runtime-llvm runtime-cet runtime-coreclr jitstress-random runtime-coreclr libraries-jitstress-random runtime-wasm-non-libtests runtime-android runtime-androidemulator runtime-ioslike runtime-ioslikesimulator runtime-linuxbionic runtime-maccatalyst runtime-coreclr pgostress runtime-coreclr jitstress-isas-avx512 runtime-libraries-mono outerloop runtime-sanitized runtime-wasm-dbgtests runtime-wasm-optional runtime-nativeaot-outerloop runtime-coreclr superpmi-collect-test runtime-diagnostics runtime-interpreter runtime-report-green runtime-coreclr hardware-intrinsics runtime-libraries-interpreter runtime-vmr-validation

sbomer · 2026-03-02T03:00:51Z

/azp run runtime-nativeaot-outerloop

sbomer · 2026-03-02T03:00:58Z

/azp run runtime-extra-platforms

azure-pipelines · 2026-03-02T03:01:08Z

Azure Pipelines successfully started running 1 pipeline(s).

azure-pipelines · 2026-03-02T03:01:13Z

Azure Pipelines successfully started running 1 pipeline(s).

sbomer · 2026-03-04T23:25:43Z

/azp run runtime-nativeaot-outerloop

sbomer · 2026-03-04T23:25:50Z

/azp run runtime-extra-platforms

azure-pipelines · 2026-03-04T23:25:52Z

Azure Pipelines successfully started running 1 pipeline(s).

azure-pipelines · 2026-03-04T23:26:06Z

Azure Pipelines successfully started running 1 pipeline(s).

Copilot

Pull request overview

Decouples NativeAOT’s ILLink preparation from ComputeIlcCompileInputs side effects by moving shared trim configuration into a dedicated target and rebuilding ILC/ILLink inputs from publish items rather than @(ManagedBinary).

Changes:

Introduced _PrepareTrimConfiguration in ILLink targets and made _ComputeManagedAssemblyToLink depend on it.
Updated NativeAOT publish pipeline to compute ILC inputs from ResolvedFileToPublish (PostprocessAssembly=true) and adjusted ordering around ILLink.
Simplified/changed ComputeManagedAssembliesToCompileToNative outputs to focus on runtime-pack files to remove and satellite assemblies.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets	Adds `_PrepareTrimConfiguration` and moves shared trim defaults/metadata out of `PrepareForILLink`.
src/coreclr/tools/aot/ILCompiler.Build.Tasks/ComputeManagedAssembliesToCompileToNative.cs	Alters MSBuild task outputs and logic to support the updated publish/trim flow.
src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets	Removes NativeAOT’s `PrepareForILLink` dependency and shifts ILC trim metadata consumption.
src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Publish.targets	Reorders publish hooks around ILLink and selects ILC managed inputs via `PostprocessAssembly`.

src/coreclr/tools/aot/ILCompiler.Build.Tasks/ComputeManagedAssembliesToCompileToNative.cs

src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Publish.targets

src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets

…esToPublishList The AfterTargets="ILLink" hook is unnecessary because ComputeLinkedFilesToPublish's own DependsOnTargets chain (via LinkNative -> IlcCompile) transitively pulls in the correct prerequisites regardless of the AfterTargets anchor. Keeping ComputeResolvedFilesToPublishList avoids an artificial coupling to ILLink and removes the need for the ILLink insertion in the test infrastructure's LinkNativeIfBuildAndRun target.

# Conflicts: # src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets # src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets

The _PrepareTrimConfiguration target was passing the full path of IntermediateAssembly to TrimmerRootAssembly, but ILLink expects assembly names (without path). This caused IL1032 errors across all CI platforms: 'Root assembly with name ...ilc.dll could not be found.' Restores the %(Filename) transform that was on main but got lost when moving this line from PrepareForILLink to _PrepareTrimConfiguration.

Initial plan

05bd1e4

Copilot AI assigned Copilot and sbomer Feb 24, 2026

github-project-automation bot added this to AppModel Feb 24, 2026

Copilot started work on behalf of sbomer February 24, 2026 16:58 View session

github-actions bot added the area-Tools-ILLink .NET linker development as well as trimming analyzers label Feb 24, 2026

Decouple ILLink managed assembly computation from ComputeIlcCompileIn…

2756749

…puts Co-authored-by: sbomer <787361+sbomer@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix ComputeIlcCompileInputs execution order before PrepareForILLink~~ Decouple NativeAOT ILLink assembly input computation from ComputeIlcCompileInputs Feb 24, 2026

Copilot AI requested a review from sbomer February 24, 2026 17:25

Copilot finished work on behalf of sbomer February 24, 2026 17:25

dotnet-policy-service bot added the linkable-framework Issues associated with delivering a linker friendly framework label Feb 25, 2026

sbomer mentioned this pull request Feb 25, 2026

Move _LinkedResolvedFileToPublishCandidate computation to after PrepareForILLink #124812

Closed

sbomer changed the title ~~Decouple NativeAOT ILLink assembly input computation from ComputeIlcCompileInputs~~ Decouple ILC from ManagedAssemblyToLink Feb 25, 2026

sbomer added 2 commits February 25, 2026 14:30

Fix BuildFrameworkNativeObjects.proj for non-SDK-style projects

b6245f7

Skip _ComputeIlcCompileInputs for framework library builds (BuildingFrameworkLibrary=true) since they use BuildOneFrameworkLibrary for input computation, not the publish-pipeline targets.

build-analysis bot mentioned this pull request Feb 26, 2026

Wasm build terminated with exit code 137 #108299

Open

Include IlcReference fallback for BuildingFrameworkLibrary builds

a45a589

build-analysis bot mentioned this pull request Feb 27, 2026

[FAIL] System.Net.Http.Functional.Tests.SocketsHttpHandler_HttpClientHandlerTest.LargeUriAndHeaders_Works #124487

Open

Merge branch 'main' into copilot/fix-ilc-compile-order

c38e2f3

Merge branch 'main' into copilot/fix-ilc-compile-order

8caa204

build-analysis bot mentioned this pull request Mar 7, 2026

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

Open

Merge branch 'main' into copilot/fix-ilc-compile-order

92f95d8

sbomer marked this pull request as ready for review March 12, 2026 17:02

sbomer requested a review from MichalStrehovsky as a code owner March 12, 2026 17:02

Copilot AI review requested due to automatic review settings March 12, 2026 17:02

Copilot started reviewing on behalf of sbomer March 12, 2026 17:08 View session

Copilot AI reviewed Mar 12, 2026

View reviewed changes

build-analysis bot mentioned this pull request Mar 13, 2026

AOT precompile failed on ios-arm64: 'No space left on device' (exit code 1) #125107

Open

sbomer added 3 commits March 13, 2026 14:07

Merge remote-tracking branch 'origin/main' into ilc-compile-order

8d6b1d5

# Conflicts: # src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets # src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets

build-analysis bot mentioned this pull request Mar 14, 2026

[browser] Wasm.Build.Tests timeout - Timed out after 10s waiting for 'WASM EXIT' #116697

Open

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Decouple ILC from ManagedAssemblyToLink#124801

Decouple ILC from ManagedAssemblyToLink#124801
Copilot wants to merge 12 commits intomainfrom
copilot/fix-ilc-compile-order

Copilot AI commented Feb 24, 2026 •

edited

Loading

Uh oh!

sbomer commented Mar 2, 2026

Uh oh!

azure-pipelines bot commented Mar 2, 2026

Uh oh!

sbomer commented Mar 2, 2026

Uh oh!

sbomer commented Mar 2, 2026

Uh oh!

azure-pipelines bot commented Mar 2, 2026

Uh oh!

azure-pipelines bot commented Mar 2, 2026

Uh oh!

sbomer commented Mar 4, 2026

Uh oh!

sbomer commented Mar 4, 2026

Uh oh!

azure-pipelines bot commented Mar 4, 2026

Uh oh!

azure-pipelines bot commented Mar 4, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Conversation

Copilot AI commented Feb 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Why a consumer would need the opposite order

Impact

Reproduction

Suggestion

Workaround

Uh oh!

sbomer commented Mar 2, 2026

Uh oh!

azure-pipelines bot commented Mar 2, 2026

Uh oh!

sbomer commented Mar 2, 2026

Uh oh!

sbomer commented Mar 2, 2026

Uh oh!

azure-pipelines bot commented Mar 2, 2026

Uh oh!

azure-pipelines bot commented Mar 2, 2026

Uh oh!

sbomer commented Mar 4, 2026

Uh oh!

sbomer commented Mar 4, 2026

Uh oh!

azure-pipelines bot commented Mar 4, 2026

Uh oh!

azure-pipelines bot commented Mar 4, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Copilot AI commented Feb 24, 2026 •

edited

Loading