[browser][CoreCLR][R2R] Double Max/Min do not preserve selected NaN payload

[lewing]

Description

The trimmed browser-wasm CoreCLR ReadyToRun library-test lane exposes four generic-math double.Max/double.Min cases where the selected NaN operand's sign/payload is not preserved. The assertion output renders both values as NaN, but the bitwise comparison detects that the result differs from the expected operand.

This resembles #133311, but that issue is explicitly scoped to Mono browser-wasm. This issue tracks the distinct CoreCLR ReadyToRun configuration so its quarantine and re-enable condition are independent.

Reproduction Steps

Run System.Runtime.Tests using browser-wasm CoreCLR with trimmed ReadyToRun images:

XHARNESS_COMMAND=test-browser ./dotnet.sh build /t:Test \
  src/libraries/System.Runtime/tests/System.Runtime.Tests/System.Runtime.Tests.csproj \
  /p:TargetOS=browser /p:TargetArchitecture=wasm /p:RuntimeFlavor=CoreCLR /p:Configuration=Release \
  /p:TestWasmReadyToRun=true /p:EnableAggressiveTrimming=true \
  /p:Scenario=WasmTestOnChrome /p:InstallChromeForTests=true

The affected member-data rows are the positive/negative NaN payload cases in MaxDouble and MinDouble from src/libraries/Common/tests/System/GenericMathTestMemberData.cs.

Expected behavior

double.Max and double.Min return the selected NaN operand with its sign and payload preserved, matching the generic-math test expectations.

Actual behavior

Four rows fail because the returned NaN has different bits from the expected NaN operand:

• MaxDouble: positive NaN with -0.0
• MaxDouble: -0.0 with negative NaN
• MinDouble: positive NaN with -0.0
• MinDouble: -0.0 with negative NaN

Regression?

Unknown. The new full trimmed ReadyToRun library sweep first exposed the behavior.

Known Workarounds

Temporarily omit only these four member-data rows when PlatformDetection.IsWasmReadyToRun is true.

Configuration

• Runtime: CoreCLR
• Target: browser-wasm
• Mode: ReadyToRun with aggressive trimming
• Browser: Chrome
• Architecture: wasm32

Other information

Related Mono-specific issue: #133311.

Note

This issue was created by GitHub Copilot based on locally reproduced CI evidence.

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[lewing]

cc @tannergooding

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