[Perf] Linux/x64: 1 Regression on 7/21/2026 3:22:49 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [2c87bd2b64912ec925d9c419c35fe82d5086b13f](https://github.com/dotnet/runtime/commit/2c87bd2b64912ec925d9c419c35fe82d5086b13f)
Compare | [5ffdd753b0146f0ec95786b2af0ab7da0b37d061](https://github.com/dotnet/runtime/commit/5ffdd753b0146f0ec95786b2af0ab7da0b37d061)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2c87bd2b64912ec925d9c419c35fe82d5086b13f...5ffdd753b0146f0ec95786b2af0ab7da0b37d061)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.IO.Tests.StringReaderReadToEndTests

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

• [ReadToEnd - 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.IO.Tests.StringReaderReadToEndTests*'
```

### System.IO.Tests.StringReaderReadToEndTests.ReadToEnd(LineLengthRange: [ 33, 128])

#### 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 linked benchmark source, performance/src/benchmarks/micro/libraries/System.IO/StringReaderReadToEndTests.cs, and the benchmarking workflow documentation. Run the provided benchmarks_ci.py filter and compare the baseline and comparison commits and reports. Done means identifying the cause of the ReadToEnd regression and confirming its performance impact is addressed.

Written by the indexing model from the issue text.