[Perf] Linux/x64: 2 Regressions on 5/12/2026 2:18:49 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [3caa97ab2ceaf0185ca6de09c6cc497dccfe6f3e](https://github.com/dotnet/runtime/commit/3caa97ab2ceaf0185ca6de09c6cc497dccfe6f3e)
Compare | [303a9aad6d3364bec0a7921966ccf21b970ab644](https://github.com/dotnet/runtime/commit/303a9aad6d3364bec0a7921966ccf21b970ab644)
Diff | [Diff](https://github.com/dotnet/runtime/compare/3caa97ab2ceaf0185ca6de09c6cc497dccfe6f3e...303a9aad6d3364bec0a7921966ccf21b970ab644)
Configs | CompilationMode:wasm, RunKind:micro

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

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

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

| 37.61 ns | 62.50 ns | 1.66 | 0.47 | False | | |
|

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

| 44.91 ns | 65.48 ns | 1.46 | 0.18 | False | | |

![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>.CopyTo(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Memory.Span<Byte>.Fill(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)