[Perf] Linux/x64: 1 Regression on 8/22/2026 9:10:25 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [58a829968e8d2624cbcb4e2ce7f1bb01cb9f652b](https://github.com/dotnet/runtime/commit/58a829968e8d2624cbcb4e2ce7f1bb01cb9f652b)
Compare | [838818c950f2448767d5feae460036e3f88e093d](https://github.com/dotnet/runtime/commit/838818c950f2448767d5feae460036e3f88e093d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/58a829968e8d2624cbcb4e2ce7f1bb01cb9f652b...838818c950f2448767d5feae460036e3f88e093d)
Configs | CompilationMode:wasm, RunKind:micro

### Regressions in System.Perf_Convert

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

• [FromBase64Chars - 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.Perf_Convert*'
```

### System.Perf_Convert.FromBase64Chars

#### 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 performance/src/benchmarks/micro/libraries/System.Runtime.Extensions/Perf.Convert.cs lines 83-84 and compare the baseline and regression commits linked in the issue. Run the benchmarks_ci.py command with the System.Perf_Convert filter, then inspect the linked test report and profiling workflow documentation. Done means the FromBase64Chars regression is explained and the benchmark no longer shows the reported slowdown.

Written by the indexing model from the issue text.