[Perf] Linux/arm64: 1 Improvement on 8/21/2026 7:05:07 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [76c60b960a2daa412c44a5061abf66f3286f6a92](https://github.com/dotnet/runtime/commit/76c60b960a2daa412c44a5061abf66f3286f6a92)
Compare | [58a829968e8d2624cbcb4e2ce7f1bb01cb9f652b](https://github.com/dotnet/runtime/commit/58a829968e8d2624cbcb4e2ce7f1bb01cb9f652b)
Diff | [Diff](https://github.com/dotnet/runtime/compare/76c60b960a2daa412c44a5061abf66f3286f6a92...58a829968e8d2624cbcb4e2ce7f1bb01cb9f652b)
Configs | CompilationMode:tiered, R2RType:r2r_interpreter, RunKind:micro

### Improvements in PerfLabTests.CastingPerf

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

• [ObjObjIsFoo - 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 'PerfLabTests.CastingPerf*'
```

### PerfLabTests.CastingPerf.ObjObjIsFoo

#### 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/runtime/perflab/CastingPerf.cs#L163-L168 and review the linked Test Report and IR history. Reproduce it with the provided benchmarks_ci.py command and compare the ARM64 AzureLinux results. Done means the improvement is understood, any actionable runtime change is identified, and the benchmark result is validated.

Written by the indexing model from the issue text.