[Perf] Linux/x64: 2 Regressions on 7/31/2026 2:45:28 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [fdccdc6954791fcde7ffa2834d75930c0efa5456](https://github.com/dotnet/runtime/commit/fdccdc6954791fcde7ffa2834d75930c0efa5456)
Compare | [ba8afceee83540ed1d867987483f74d4ad2cfae9](https://github.com/dotnet/runtime/commit/ba8afceee83540ed1d867987483f74d4ad2cfae9)
Diff | [Diff](https://github.com/dotnet/runtime/compare/fdccdc6954791fcde7ffa2834d75930c0efa5456...ba8afceee83540ed1d867987483f74d4ad2cfae9)
Configs | CompilationMode:wasm, RunKind:micro

### Regressions in System.Buffers.Text.Tests.Utf8FormatterTests

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

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

| 1.31 μs | 1.52 μs | 1.16 | 0.15 | False | | |
|

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

| 1.36 μs | 1.54 μs | 1.13 | 0.18 | False | | |

![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.Buffers.Text.Tests.Utf8FormatterTests*'
```

### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterDouble(value: 1.7976931348623157E+308)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterDouble(value: -1.7976931348623157E+308)

#### 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.Buffers/Utf8FormatterTests.cs lines 53-55 and compare the listed baseline and compare commits. Run benchmarks_ci.py with the provided Utf8FormatterTests filter, then investigate the two FormatterDouble regressions; done means identifying and addressing the regression while preserving benchmark results.

Written by the indexing model from the issue text.