[Perf] Windows/x64: 2 Improvements on 7/6/2026 12:45:47 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [ff279bafa8ca2fbf920b605868e9b0a2c0497034](https://github.com/dotnet/runtime/commit/ff279bafa8ca2fbf920b605868e9b0a2c0497034)
Compare | [d720474264849c4dafe6e28dc5bd679b4ddbe5fe](https://github.com/dotnet/runtime/commit/d720474264849c4dafe6e28dc5bd679b4ddbe5fe)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ff279bafa8ca2fbf920b605868e9b0a2c0497034...d720474264849c4dafe6e28dc5bd679b4ddbe5fe)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Numerics.Tests.Perf_BitOperations

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

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

| 360.89 ns | 279.23 ns | 0.77 | 0.20 | False | | |
|

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

| 360.69 ns | 279.26 ns | 0.77 | 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
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Numerics.Tests.Perf_BitOperations*'
```

### System.Numerics.Tests.Perf_BitOperations.LeadingZeroCount_ulong

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Numerics.Tests.Perf_BitOperations.TrailingZeroCount_ulong

#### 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 dotnet/performance/src/benchmarks/micro/libraries/System.Numerics.BitOperations/Perf_BitOperations.cs, especially the LeadingZeroCount_ulong and TrailingZeroCount_ulong entries. Run the provided benchmarks_ci.py command and compare the Windows x64 results with the linked baseline and comparison commits. Done requires confirming whether the reported improvement is expected and identifying an actionable runtime change or follow-up.

Written by the indexing model from the issue text.