[ci-scan] Build break: Crossgen2 OOM compiling HugeArray1.dll on x86 R2R

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Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1432995
Build error leg or test failing: coreclr Pri1 Runtime Tests Run R2R_CG2 windows x86 checked - jit64_3 (HugeArray1.dll)

Error Details

Crossgen2 crashes with System.OutOfMemoryException while R2R-compiling HugeArray1.dll on windows x86 (32-bit). The OOM occurs in ObjectWriter.EmitChecksums when trying to allocate a large array via MemoryStream.ToArray(). This is inherent to x86's limited address space when processing very large test assemblies.

This failure is persistent across the entire scanned window (20+ builds from 2026-05-17 through 2026-05-23).

"Running CrossGen2:  crossgen2.exe @"HugeArray1.dll.rsp""
Emitting R2R PE file: HugeArray1.dll
Unhandled exception. System.OutOfMemoryException: Insufficient memory to continue the execution of the program.
   at System.GC.<AllocateUninitializedArray>g__AllocateNewUninitializedArray|54_0[T](Int32, Boolean)
   at System.IO.MemoryStream.ToArray()
   at ILCompiler.ObjectWriter.ObjectWriter.EmitChecksums(Stream, List`1)
   at ILCompiler.ObjectWriter.ObjectWriter.EmitObject(Stream, IReadOnlyCollection`1, IObjectDumper, Logger)
   at ILCompiler.DependencyAnalysis.ReadyToRunObjectWriter.EmitReadyToRunObjects(ReadyToRunContainerFormat, Logger)
   at ILCompiler.ReadyToRunCodegenCompilation.Compile(String)
Crossgen2 failed with exitcode - -1073740791

Affected legs:

• runtime-coreclr outerloop (def 108): coreclr Pri1 Runtime Tests Run R2R_CG2 windows x86 checked

First build it occurred: 1423687 (2026-05-17). Persistent across the entire scanned window; true origin may predate 2026-05-17.

Error Message

{
  "ErrorMessage": ["HugeArray1.dll", "System.OutOfMemoryException: Insufficient memory to continue the execution of the program."],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Generated by CI Outer-Loop Failure Scanner · ● 45.7M · ◷

Report

Build	Repository	Test	Pull Request
1442223	dotnet/runtime	jit64_3.WorkItemExecution
1441697	dotnet/runtime	jit64_3.WorkItemExecution
1440977	dotnet/runtime	jit64_3.WorkItemExecution	#128702
1439560	dotnet/runtime	jit64_3.WorkItemExecution
1438124	dotnet/runtime	jit64_3.WorkItemExecution
1437608	dotnet/runtime	jit64_3.WorkItemExecution
1434871	dotnet/runtime	jit64_3.WorkItemExecution
1433552	dotnet/runtime	jit64_3.WorkItemExecution

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
2	8	8

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