Adding the vector constants property extensions that are only supported for certain T

[tannergooding]

This resolves #117569

[bollhals]

If you don't mind me asking, for my education:
Why does a change like that require changes in jit?
Would it have regressed code gen due not inlining them properly or is it to reduce the work the jit has to do or something else?

[tannergooding]

Why does a change like that require changes in jit?

The JIT work isn't strictly required and in most cases you'll get the expected codegen.

However, there is still some impact to JIT throughput and general inlining budget which can be optimized by special-casing these "core helpers". So rather than having to go through the recognize method call->scan IL of callee->compute profitability->check against budget->inline il (if within budget)->potentially other opts/transforms->constant we can just do recognize method call->constant.

Since these types are "perf critical" and the logic to support them in the JIT is relatively trivial, we do so to ensure it provides that minimally better experience.

[bollhals]

Thanks for the explanation 👍🏼, very much appreciated.

[Copilot]

Pull Request Overview

This PR adds vector constant property extensions that are only available for certain element types (T). These extensions provide convenient access to common mathematical and special values like One, Zero, NaN, Pi, E, Tau, NegativeZero, NegativeInfinity, etc. as vector constants with all lanes populated with the same value.

Key changes:

• Adds extension properties for Vector64<T>, Vector128<T>, Vector256<T>, Vector512<T>, and Vector<T> types
• Properties are constrained by generic constraints (e.g., IFloatingPointConstants<T>, IFloatingPointIeee754<T>, ISignedNumber<T>)
• Updates test files to use the new properties instead of Vector.Create() calls

Reviewed Changes

Copilot reviewed 55 out of 57 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/libraries/System.Runtime.Intrinsics/ref/System.Runtime.Intrinsics.cs	Adds API surface definitions for the new extension properties
src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector*.cs	Implements the extension properties for all vector types
src/coreclr/jit/hwintrinsic*.cpp	Adds JIT intrinsic handling for the new properties
src/coreclr/jit/hwintrinsiclist*.h	Registers the new intrinsic identifiers
Various test files	Updates existing tests to use new property syntax instead of Vector.Create()