Enable CA1516 Use Cross-Platform Intrinsics

[stephentoub]

No description provided.

[Copilot]

Pull Request Overview

This PR enables the CA1516 analyzer rule ("Use cross-platform intrinsics") which encourages the use of cross-platform SIMD operator overloads instead of platform-specific intrinsic methods. The changes replace platform-specific intrinsic calls (like AdvSimd.ShiftRightArithmetic, Sse2.Or, Avx2.Add) with their equivalent C# operator overloads (like >>, |, +) that work across multiple platforms.

Key changes:

• Replaced arithmetic and bitwise intrinsic method calls with operator overloads throughout the codebase
• Enabled CA1516 as a warning in source code analysis configuration
• Disabled CA1516 in test code and intrinsics implementation folders where the rule shouldn't apply

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
eng/CodeAnalysis.src.globalconfig	Enabled CA1516 as a warning for source code
eng/CodeAnalysis.test.globalconfig	Disabled CA1516 for test code
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/.editorconfig	Disabled CA1516 for intrinsics implementations
src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf8Utility.Validation.cs	Replaced AdvSimd.ShiftRightArithmetic and AdvSimd.And with >> and & operators
src/libraries/System.Private.CoreLib/src/System/Text/Latin1Utility.cs	Replaced Sse2.Or with `
src/libraries/System.Private.CoreLib/src/System/Text/Ascii.Utility.cs	Replaced AdvSimd.ShiftRightArithmetic and AdvSimd.And with >> and & operators
src/libraries/System.Private.CoreLib/src/System/SearchValues/IndexOfAnyAsciiSearcher.cs	Replaced AdvSimd.ShiftRightArithmetic with >> operator
src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Helper/Base64EncoderHelper.cs	Replaced Avx2.And, Avx2.MultiplyLow, Avx2.Or, Avx2.Subtract, Avx2.Add, and AdvSimd.ShiftRightLogical with operators
src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Helper/Base64DecoderHelper.cs	Replaced Avx2.And and Avx2.Add with & and + operators
src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/TensorPrimitives.LeadingZeroCount.cs	Replaced shift and bitwise intrinsics with operator overloads
src/libraries/Common/src/System/HexConverter.cs	Replaced AdvSimd.ShiftLeftLogical and PackedSimd.ShiftLeft with << operator

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[tannergooding]

Glad to see this picking up some cases and simplifying the implementation!

There's more scenarios we'll want to add to the analyzer over time, but this is a great first step!

[stephentoub]

@tannergooding, please also see dotnet/sdk#51299. I hit that while running the analyzer (it fails to show the description in the diagnostic as a result).