[Perf] Linux/x64: 2 Regressions on 9/8/2026 9:15:08 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [610385584005eb07e1251fc073fe065a462fff3e](https://github.com/dotnet/runtime/commit/610385584005eb07e1251fc073fe065a462fff3e)
Compare | [792dc9c26ad470580271b41e011092d8aaad50d9](https://github.com/dotnet/runtime/commit/792dc9c26ad470580271b41e011092d8aaad50d9)
Diff | [Diff](https://github.com/dotnet/runtime/compare/610385584005eb07e1251fc073fe065a462fff3e...792dc9c26ad470580271b41e011092d8aaad50d9)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.Collections.AddGivenSize<String>

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

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

| 1.68 ms | 1.96 ms | 1.17 | 0.39 | False | | |

![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.Collections.AddGivenSize*'
```

### System.Collections.AddGivenSize<String>.IDictionary(Size: 512)

#### 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)

---

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [610385584005eb07e1251fc073fe065a462fff3e](https://github.com/dotnet/runtime/commit/610385584005eb07e1251fc073fe065a462fff3e)
Compare | [792dc9c26ad470580271b41e011092d8aaad50d9](https://github.com/dotnet/runtime/commit/792dc9c26ad470580271b41e011092d8aaad50d9)
Diff | [Diff](https://github.com/dotnet/runtime/compare/610385584005eb07e1251fc073fe065a462fff3e...792dc9c26ad470580271b41e011092d8aaad50d9)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in GuardedDevirtualization.ThreeClassVirtual

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

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

| 55.40 ns | 60.22 ns | 1.09 | 0.19 | False | | |

![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 'GuardedDevirtualization.ThreeClassVirtual*'
```

### GuardedDevirtualization.ThreeClassVirtual.Call(testInput: pB=0.00 pD=0.67)

#### 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 sources at src/benchmarks/micro/libraries/System.Collections/Add/AddGivenSize.cs#L73-L75 and src/benchmarks/micro/runtime/Devirtualization/GuardedThreeClassVirtual.cs#L34-L45. Reproduce both cases with the provided benchmarks_ci.py commands, then compare the baseline and test commits and inspect the linked reports. Done means the regressions are understood and addressed, with benchmark results confirming the change.

Written by the indexing model from the issue text.