[Perf] Linux/x64: 2 Regressions on 8/14/2026 4:30:00 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [691fd960eb500743b4be71373b11b2263bdbc318](https://github.com/dotnet/runtime/commit/691fd960eb500743b4be71373b11b2263bdbc318)
Compare | [6276bd4a23e9e21597ccccba91f908917bc8e189](https://github.com/dotnet/runtime/commit/6276bd4a23e9e21597ccccba91f908917bc8e189)
Diff | [Diff](https://github.com/dotnet/runtime/compare/691fd960eb500743b4be71373b11b2263bdbc318...6276bd4a23e9e21597ccccba91f908917bc8e189)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.Numerics.Tensors.Tests.Perf_FloatingPointTensorPrimitives<Double>

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

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

| 48.54 μs | 60.71 μs | 1.25 | 0.03 | False | | |
|

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

| 2.11 μs | 2.34 μs | 1.11 | 0.05 | 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.Numerics.Tensors.Tests.Perf_FloatingPointTensorPrimitives*'
```

### System.Numerics.Tensors.Tests.Perf_FloatingPointTensorPrimitives<Double>.FusedMultiplyAdd_Vectors(BufferLength: 3079)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Numerics.Tensors.Tests.Perf_FloatingPointTensorPrimitives<Double>.FusedMultiplyAdd_Vectors(BufferLength: 128)

#### 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 src/benchmarks/micro/libraries/System.Numerics.Tensors/Perf_FloatingPointTensorPrimitives.cs, especially FusedMultiplyAdd_Vectors, and run the provided benchmarks_ci.py command. Compare the baseline and test commits and inspect the linked test report and history graphs. Done means the Linux/x64 WebAssembly regression is explained and the benchmark no longer shows the reported slowdown.

Written by the indexing model from the issue text.