[Perf] Windows/x86: 1 Improvement on 7/20/2026 8:16:56 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [630a7009ba484fe96b8f0b81e2f4cc0bb6827903](https://github.com/dotnet/runtime/commit/630a7009ba484fe96b8f0b81e2f4cc0bb6827903)
Compare | [4d9d5a153993dbeb30910ece8ad346985c55d85d](https://github.com/dotnet/runtime/commit/4d9d5a153993dbeb30910ece8ad346985c55d85d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/630a7009ba484fe96b8f0b81e2f4cc0bb6827903...4d9d5a153993dbeb30910ece8ad346985c55d85d)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Memory.Span<Int32>

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

• [EndsWith - 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 'System.Memory.Span*'
```

### System.Memory.Span<Int32>.EndsWith(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)

Start with the System.Memory Span.EndsWith(Size: 512) benchmark and its source at performance/src/benchmarks/micro/libraries/System.Memory/Span.cs#L74-L75. Run the provided benchmarks_ci.py command, then inspect the linked test report, history, and disassembly to understand the x86 Windows improvement. Done should be a verified, reproducible performance change, but the issue does not specify what code should change.

Written by the indexing model from the issue text.