[Perf] Windows/x86: 1 Regression on 7/17/2026 10:18:08 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Compare | [e7c3d6567c4d78e0c10627fa89939767464478c2](https://github.com/dotnet/runtime/commit/e7c3d6567c4d78e0c10627fa89939767464478c2)
Diff | [Diff](https://github.com/dotnet/runtime/compare/09f41d9272e6dcff30bfa15653e124d013167e05...e7c3d6567c4d78e0c10627fa89939767464478c2)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.IO.Tests.BinaryWriterExtendedTests

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

• [WriteAsciiCharArray - 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.IO.Tests.BinaryWriterExtendedTests*'
```

### System.IO.Tests.BinaryWriterExtendedTests.WriteAsciiCharArray(StringLengthInChars: 32)

#### 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)

The regression is reported by System.IO.Tests.BinaryWriterExtendedTests.WriteAsciiCharArray and points to BinaryWriterExtendedTests.cs lines 29-34. Start by running the provided benchmarks_ci.py command, then compare the baseline and test commits and inspect the linked report. Done means the Windows/x86 performance regression is explained and the benchmark no longer shows the reported slowdown.

Written by the indexing model from the issue text.