Update the vector types to support having char as the element type

[tannergooding]

This resolves #127611

It does some minimal cleanup of the type checks to centralize things where typeof(T) == typeof(char) checks had to be inserted. It also normalizes the ref files so that the generation works and normalizes Shuffle to use a helper so we don't need so much duplicated code for every type we need to support.

It does not go and cleanup up S.P.Corelib to directly use Vector128<char> and friends where relevant, I'm leaving that for a separate work item.

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[Copilot]

Pull request overview

This PR extends the SIMD vector APIs and runtime support to treat char as a supported element type across Vector, Vector64/128/256/512, including new AsChar / Create(char) / shift / shuffle overloads, and updates the JIT/Mono pipelines to recognize char element types.

Changes:

• Adds char to supported scalar/vector type checks and introduces Scalar<T> helpers to centralize type-category logic.
• Introduces Vector*<char>-specific public APIs (create, shifts, shuffle, debug views) and ref-file updates to expose them.
• Updates CoreCLR JIT and Mono SIMD handling to classify char appropriately (typically as a 16-bit unsigned element).

Reviewed changes

Copilot reviewed 25 out of 27 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/mono/mono/mini/simd-intrinsics.c	Maps Vector128<char> element type to U2 for SIMD lowering/import.
src/mono/mono/mini/mini.h	Expands “vector primitive” type check to include char.
src/mono/mono/mini/interp/transform-simd.c	Normalizes interpreter SIMD element type char to U2.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector64DebugView_1.cs	Adds debugger CharView for Vector64<T>.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector64.cs	Adds char APIs (As/Create/Shift/Shuffle) and refactors shuffle fallback logic.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector64_1.cs	Switches IsSupported logic to Scalar<T>.IsSupported.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector512DebugView_1.cs	Adds debugger CharView for Vector512<T>.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector512.cs	Adds char APIs and refactors shuffle fallback logic.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector512_1.cs	Switches IsSupported logic to Scalar<T>.IsSupported.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector256DebugView_1.cs	Adds debugger CharView for Vector256<T>.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector256.cs	Adds char APIs and refactors shuffle fallback logic.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector256_1.cs	Switches IsSupported logic to Scalar<T>.IsSupported.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector128DebugView_1.cs	Adds debugger CharView for Vector128<T>.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector128.cs	Adds char APIs and refactors shuffle fallback logic (plus intrinsic paths).
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector128_1.cs	Switches IsSupported logic to Scalar<T>.IsSupported.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/SimdVectorExtensions.cs	Removes unused usings (cleanup).
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Scalar.cs	Centralizes scalar type traits and adds char arithmetic/bit ops support.
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/ISimdVector_2.cs	Removes unused using (cleanup).
src/libraries/System.Private.CoreLib/src/System/Numerics/VectorDebugView_1.cs	Adds debugger CharView for Vector<T>.
src/libraries/System.Private.CoreLib/src/System/Numerics/Vector.cs	Adds Vector<char> APIs (As/Shift) and uses Scalar<T> categorization.
src/libraries/System.Private.CoreLib/src/System/Numerics/Vector_1.cs	Makes Vector<T>.IsSupported rely on Scalar<T>.IsSupported.
src/libraries/System.Numerics.Vectors/ref/System.Numerics.Vectors.cs	Updates public ref surface for Vector<char> APIs and normalizes ref formatting.
src/coreclr/vm/jitinterface.cpp	Returns CORINFO_TYPE_CHAR for ELEMENT_TYPE_CHAR in numeric classification.
src/coreclr/tools/Common/TypeSystem/Common/TypeDesc.cs	Treats char as primitive numeric for type system classification.
src/coreclr/jit/importercalls.cpp	Allows SIMD base type char in intrinsic import/type checks.

[Copilot]

Pull request overview

Copilot reviewed 31 out of 33 changed files in this pull request and generated 1 comment.