[Perf] Windows/x86: 1 Improvement on 6/14/2026 5:53:19 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [39452c512b1021f7fbc349bb2953db6ac2659623](https://github.com/dotnet/runtime/commit/39452c512b1021f7fbc349bb2953db6ac2659623)
Compare | [98bfa17c9f3910eec30099b7ac140d8a09df6227](https://github.com/dotnet/runtime/commit/98bfa17c9f3910eec30099b7ac140d8a09df6227)
Diff | [Diff](https://github.com/dotnet/runtime/compare/39452c512b1021f7fbc349bb2953db6ac2659623...98bfa17c9f3910eec30099b7ac140d8a09df6227)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Memory.Span<Int32>

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|

• [LastIndexOfValue - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

![graph]()
[Test Report]()

### Repro
General Docs link: https://github.com/dotnet/performance/blob/main/docs/benchmarking-workflow-dotnet-runtime.md

```cmd
git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Memory.Span*'
```

### System.Memory.Span<Int32>.LastIndexOfValue(Size: 3000)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

[Profiling workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/profiling-workflow-dotnet-runtime.md)
[Benchmarking workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/benchmarking-workflow-dotnet-runtime.md)

Start with the benchmark source at src/benchmarks/micro/libraries/System.Memory/Span.cs#L103-L104 and run the provided benchmarks_ci.py command for System.Memory.Span. Review the linked test report and performance data; the issue does not define a code change or acceptance criterion, so completion requires clarifying the cause and expected result.

Written by the indexing model from the issue text.