[Perf] Linux/x64: 1 Regression on 8/18/2026 8:18:56 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [633df28f492810dd8b152eb72f3d77aae703db89](https://github.com/dotnet/runtime/commit/633df28f492810dd8b152eb72f3d77aae703db89)
Compare | [6550ccf7827cdc363035f8927f68a34edb01bf22](https://github.com/dotnet/runtime/commit/6550ccf7827cdc363035f8927f68a34edb01bf22)
Diff | [Diff](https://github.com/dotnet/runtime/compare/633df28f492810dd8b152eb72f3d77aae703db89...6550ccf7827cdc363035f8927f68a34edb01bf22)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.Memory.Span<Byte>

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

• [IndexOfAnyFiveValues - 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Memory.Span*'
```

### System.Memory.Span<Byte>.IndexOfAnyFiveValues(Size: 512)

#### 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 src/benchmarks/micro/libraries/System.Memory/Span.cs lines 100-101 and the benchmarking workflow linked in the issue. Run the provided benchmarks_ci.py command, then compare the baseline and test reports for IndexOfAnyFiveValues(Size: 512). Done means the reported regression is understood and the benchmark no longer shows the regression after the change.

Written by the indexing model from the issue text.