Use WASM CoreLib when compiling crossgen2 WASM unit tests by jtschuster · Pull Request #131024 · dotnet/runtime

jtschuster · 2026-07-19T01:32:23Z

ILCompiler.ReadyToRun.Tests uses the host corelib to compile for wasm. If crossgen ever takes a dependency on a wasm-only member being present in corelib, it could cause failures. Since browser-wasm corelib can be built cross-platform, enforce a wasm runtime pack as a prerequisite for running the tests in CI. For local development, a host-targeting corelib can be used as a fallback with a warning.

Adds a pipeline job to build the wasm runtime pack for running in CI.

We do also have tests that compile for the host OS on arm32 (if we support arm on that OS -- linux only now), so we also would run into this issue if there are any arm32-specific members that crossgen2 relies on for compilation. I think this is less likely to cause problems, but it's called out in comments in case tests start failing for that reason.

- Use CopyAllJitLibrariesToAotCompilerOutput=true instead of copying ourselves. - Set crossgenDir based on crossgen2_inbuild.csproj output items - Reorder properties and items to keep related items close to each other

…ter-wasm-r2r-crossgen-test

azure-pipelines · 2026-07-19T01:33:04Z

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Copilot

Pull request overview

This PR updates the ReadyToRun crossgen2 test runner and CI wiring so WASM-targeted R2R compilations can reference the browser-wasm runtime pack (including WASM System.Private.CoreLib) when it’s available, instead of always using the host runtime pack.

Changes:

Add browser-wasm runtime-pack path plumbing (and an opt-in “require wasm references” switch) to the ILCompiler.ReadyToRun.Tests test infrastructure.
Add a per-compilation target selector (TargetRid) so tests can request browser-wasm (or host-arm) crossgen2 args and reference sets.
Update pipeline to build + publish browser-wasm managed runtime-pack artifacts and download them into the CLR tools test job.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

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File	Description
src/installer/pkg/sfx/Microsoft.NETCore.App/Microsoft.NETCore.App.Runtime.CoreCLR.sfxproj	Makes `IncludeStaticLibrariesInPack` overridable so CI can disable static libs for browser/wasi runtime-pack builds.
src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCasesRunner/TestPaths.cs	Simplifies path config and adds optional wasm runtime-pack locations + `RequireWasmReferences` switch.
src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCasesRunner/R2RTestRunner.cs	Chooses host vs browser-wasm reference paths per compilation and passes reference paths into the resolver.
src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCasesRunner/R2RTestCaseCompiler.cs	Changes Roslyn compilation reference setup to consume an explicit reference list.
src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCasesRunner/R2RResultChecker.cs	Updates `SimpleAssemblyResolver` to resolve framework assemblies from a provided reference set rather than `TestPaths`.
src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCasesRunner/R2RDriver.cs	Removes the dedicated “target arch arm” option in favor of `TargetRid`-driven args.
src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCases/R2RTestSuites.cs	Updates wasm and arm test cases to use `TargetRid` and tightens arm test gating.
src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/ILCompiler.ReadyToRun.Tests.csproj	Adds wasm runtime-pack discovery/config propagation and CI-oriented validation/warnings.
eng/pipelines/runtime.yml	Builds browser-wasm libs for CLR tools tests, publishes them as artifacts, and downloads them into the tools test job.

Comments suppressed due to low confidence (1)

src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCasesRunner/TestPaths.cs:8

System.Text.RegularExpressions is no longer used in this file after removing the config-probing helpers; leaving it will either produce an unnecessary compiler warning (CS8019) or fail builds that treat warnings as errors.

using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using Xunit.Abstractions;

Copilot

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Comments suppressed due to low confidence (2)

src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/TestCasesRunner/R2RTestCaseCompiler.cs:77

R2RTestCaseCompiler now compiles test assemblies with OptimizationLevel.Debug, which changes the IL shape (and potentially crossgen2 output/validations) and seems unrelated to the PR’s wasm-reference selection. Unless there’s a specific reason, keeping Release here avoids altering baseline test behavior.

            new CSharpCompilationOptions(outputKind)
                .WithOptimizationLevel(OptimizationLevel.Debug)
                .WithAllowUnsafe(true)
                .WithNullableContextOptions(NullableContextOptions.Enable));

src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/ILCompiler.ReadyToRun.Tests.csproj:67

MSBuild Exists(...) checks should avoid hardcoding \ path separators. On non-Windows builds this can cause false negatives (and in this case, the error is raised very early). Using / (or NormalizeDirectory) keeps the check portable.

    <Error Condition="!Exists('$(CoreCLRArtifactsPath)\$(BuildArchitecture)\crossgen2')"
           Text="Crossgen2 inbuild publish directory '$(CoreCLRArtifactsPath)\$(BuildArchitecture)\crossgen2' does not exist. This is a build authoring error and should be generated in the test project build." />

azure-pipelines · 2026-07-20T21:07:38Z

Azure Pipelines: Successfully started running 5 pipeline(s). 11 pipeline(s) were filtered out due to trigger conditions. There may be pipelines that require an authorized user to comment /azp run to run.

Copilot

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

src/coreclr/tools/aot/ILCompiler.ReadyToRun.Tests/ILCompiler.ReadyToRun.Tests.csproj:67

The ValidatePathsExist target builds a path using backslashes (e.g. '$(CoreCLRArtifactsPath)$(BuildArchitecture)\crossgen2'). On non-Windows agents this can become a literal backslash in the path and cause a false failure even when the directory exists. Use forward slashes or NormalizeDirectory/NormalizePath to keep the Exists check cross-platform.

    <Error Condition="!Exists('$(CoreCLRArtifactsPath)\$(BuildArchitecture)\crossgen2')"
           Text="Crossgen2 inbuild publish directory '$(CoreCLRArtifactsPath)\$(BuildArchitecture)\crossgen2' does not exist. This is a build authoring error and should be generated in the test project build." />

+                _output.WriteLine($"Using browser-wasm runtime pack references from '{wasmRuntimePackDir}'");
+                paths =
+                [
+                    ..Directory.GetFiles(wasmRuntimePackDir, "*.dll"),
+                    wasmCoreLibPath
+                ];
+                return paths;


+        paths = [
+            ..Directory.GetFiles(_paths.RuntimePackDir, "*.dll"),
+            coreLibPath
+        ];


MichalStrehovsky · 2026-07-20T23:44:33Z

+            # Depend on the browser-wasm libraries built below so the wasm crossgen2 R2R test
+            # (ILCompiler.ReadyToRun.Tests) can compile against real browser-wasm references.
+            dependsOn:
+            - build_browser_wasm_linux_Release_CLR_Tools_Tests_WasmLibs


Instead of all this hackery and optional WASM builds, can we add a separate ToolsTests leg (ReadyToRunTests) that simply builds the runtime as -arch wasm and then one more leg that builds as -arch arm?

We might want to move ILCompiler.ReadyToRun.Tests out of toolstests as part of that since none of the other toolstests are actually architecture specific and it's a waste of time to run them.

I believe we'll not need any of the project file hackery if we do that because CoreLib that is passed to the tests will simply be the correct corelib. The attributes in the tests can still decide whether the test should run or not.

We'd also be able to undo parts of #129791, specifically ba3edd9 and a2b9874 because we'd no longer need host-flavored flavor of all the JITs, only the host-flavored JIT that we're testing.

can we add a separate ToolsTests leg (ReadyToRunTests) that simply builds the runtime as -arch wasm

I don't think we'd be able to shell out to crossgen if we run ILCompiler.ReadyToRun.Tests on browser-wasm, would we?

Or am I misunderstanding what you mean?

jtschuster added 4 commits July 18, 2026 18:09

Use Wasm runtime pack for building wasm in ILCompiler.ReadyToRun.Tests

fa59f6d

Clean up ILCompiler.ReadyToRun.Tests.csproj

4f17299

- Use CopyAllJitLibrariesToAotCompilerOutput=true instead of copying ourselves. - Set crossgenDir based on crossgen2_inbuild.csproj output items - Reorder properties and items to keep related items close to each other

Merge branch 'main' of https://github.com/dotnet/runtime into jtschus…

03717e7

…ter-wasm-r2r-crossgen-test

Cleanup

898d14b

Copilot AI review requested due to automatic review settings July 19, 2026 01:32

github-actions Bot added the area-crossgen2-coreclr only use for closed issues label Jul 19, 2026

dotnet-policy-service Bot assigned jtschuster Jul 19, 2026

jtschuster changed the title ~~Jtschuster wasm r2r crossgen test~~ Use WASM CoreLib when compiling crossgen2 WASM unit tests Jul 19, 2026

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jtschuster added area-ReadyToRun and removed area-crossgen2-coreclr only use for closed issues labels Jul 20, 2026

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Check runtime pack dir exists before enumerating

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jtschuster requested review from MichalStrehovsky, davidwrighton and jkoritzinsky July 20, 2026 21:06

jtschuster marked this pull request as ready for review July 20, 2026 21:07

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Use WASM CoreLib when compiling crossgen2 WASM unit tests#131024

Use WASM CoreLib when compiling crossgen2 WASM unit tests#131024
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