[Perf] Linux/x64: 2 Improvements on 3/26/2026 9:27:27 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [91557f54f15bac8fbb5c7acf994910cbd6071991](https://github.com/dotnet/runtime/commit/91557f54f15bac8fbb5c7acf994910cbd6071991)
Compare | [039ef3fc2820ca493545f5ec8d3248d4566bee07](https://github.com/dotnet/runtime/commit/039ef3fc2820ca493545f5ec8d3248d4566bee07)
Diff | [Diff](https://github.com/dotnet/runtime/compare/91557f54f15bac8fbb5c7acf994910cbd6071991...039ef3fc2820ca493545f5ec8d3248d4566bee07)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Improvements in System.Tests.Perf_Int64

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

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

| 51.99 ns | 45.14 ns | 0.87 | 0.25 | False | | |
|

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

| 68.07 ns | 58.79 ns | 0.86 | 0.12 | False | | |

[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.Tests.Perf_Int64*'
```

### System.Tests.Perf_Int64.ToString(value: 12345)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Int64.ToString(value: 9223372036854775807)

#### 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 in performance/src/benchmarks/micro/libraries/System.Runtime/Perf.Int64.cs at lines 26-28, then run the documented benchmarks_ci.py command for System.Tests.Perf_Int64. Review the linked test report and profiling or benchmarking workflow docs; the payload records an improvement, but does not identify a change to make or a concrete completion condition.

Written by the indexing model from the issue text.