[ci-scan] Test failure: GCRefStress_AllVerificationsPass misses Windows x86 SearchValues.Create roots (CrossModule) #135217

Description

Windows x86 cDAC GC-reference stress misses roots in System.Buffers.SearchValues.Create, TypeNameParserHelpers..cctor, and the MemoryExtensions.Min/MinMaxInteger frames while running the CrossModule debuggee. The runtime reports 105 references and the cDAC reports 99. Five of the 27 frames mismatch; the other 22 agree.

This is a different signature from #135085 (EventSource, cDAC=7 RT=47) and #135086 (PrestubMethodFrame frame #0), and neither of those KBEs matches it.

Reproduction Steps

Observed in runtime-diagnostics build 1623331, windows-x86 release CdacStressTest, in GCRefStress_AllVerificationsPass for CrossModule. The PR that hit it (#135204) only changes a wasm perf pipeline template that runtime-diagnostics doesn't use. No deterministic local repro.

Configuration

Windows x86 runtime, Release, cDAC GC-reference stress, CrossModule debuggee. The Helix queue is Windows.Amd64.Open.

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1623331
Build error leg or test failing: windows-x86 release CdacStressTest - Microsoft.Diagnostics.DataContractReader.Tests.GCStress.CdacStressTests.GCRefStress_AllVerificationsPass
Pull request: #135204

Error Details

GCREFS stress test 'CrossModule' had 2 failure(s) and 0 known issue(s) out of 4836 verifications.

[FAIL] Thread=0x1d74 IP=0x7419B16C cDAC=99 RT=105 frames=27 (match=22 mismatch=5 known_nie=0)
  Frame #8 System.Buffers.SearchValues.Create(System.ReadOnlySpan`1<Char>) [MISMATCH] cDAC=0 RT=2 SP_cDAC=0x0 SP_RT=0x0
  Frame #16 System.Reflection.Metadata.TypeNameParserHelpers..cctor() [MISMATCH] cDAC=0 RT=1 SP_cDAC=0x0 SP_RT=0x0
  Frame #24 System.MemoryExtensions.Min[[System.Char, System.Private.CoreLib]](System.ReadOnlySpan`1<Char>) [MISMATCH] cDAC=0 RT=1
  Frame #25 System.Buffers.SearchValues.TryGetSingleRange[[System.Char, System.Private.CoreLib]](...) [MISMATCH] cDAC=0 RT=2
  Frame #26 System.MemoryExtensions.MinMaxInteger[[System.Char, ...]](System.ReadOnlySpan`1<Char>) [MISMATCH] cDAC=1 RT=1
    [ONLY(cDAC)] Addr=0x337BAA0 Obj=0x7 Flags=0x1
    [ONLY(RT)] Addr=0x337BAA8 Obj=0xC467148 Flags=0x1

Stack Trace:
  CdacStressTestBase.cs(180,0): at Microsoft.Diagnostics.DataContractReader.Tests.GCStress.CdacStressTestBase.AssertAllPassed(CdacStressResults results, String debuggeeName)
  CdacStressTests.cs(64,0): at Microsoft.Diagnostics.DataContractReader.Tests.GCStress.CdacStressTests.GCRefStress_AllVerificationsPass(Debuggee debuggee)

Error Message

{
  "ErrorMessage": "Frame #8 System.Buffers.SearchValues.Create(System.ReadOnlySpan`1<Char>) [MISMATCH] cDAC=0 RT=2",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1623331
Error message validated: [Frame #8 System.Buffers.SearchValues.Create(System.ReadOnlySpan1) [MISMATCH] cDAC=0 RT=2`]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 10/5/2026 2:37:46 PM UTC

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Summary