.NET 5 Preview 5


Here are some of the improvements in Preview 5.

RyuJIT improvements

The following improvements were made to the RyuJIT JIT compiler:

  • New, much faster, portable implementation of tail-call helpers: This implements tail-call-via-help support for all platforms supported by the runtime. In this new mechanism, the JIT asks the runtime for help whenever it realizes it will need a helper to perform a tail-call, i.e., when it sees an explicit tail. Prefixed call that it cannot make into a fast jump-based tail-call.
  • Continued ARM64 hardware intrinsics implementation progress
    • Implement ASIMD Extract Insert ExtractVector64 ExtractVector128
    • Implement ASIMD widening, narrowing, saturating intrinsics
    • Add VectorTableList and TableVectorExtension intrinsics
    • Add support of CreateScalarUnsafe() for arm64 intrinsic
    • ARM64 intrinsic support for Vector64.Create() and Vector128.Create()
    • Optimize BitOperations.PopCount() with arm64 intrinsics
  • Improved JIT speed in a case that was affecting regular expression compilation
  • Improved Intel architecture performance using new hardware intrinsics BSF/BSR.
  • Implement Vector.AllBitsSet

Native exports

It enables exports for native binaries that call into .NET code in .NET 5.0.

  • The building block of the feature is hosting API support for UnmanagedCallersOnlyAttribute.
  • It is a building-block for creating higher-level experiences that provides a more complete experience for publishing .NET components as native libraries.

The native exports project enables you to:

  • Expose custom native exports.
  • Doesn't require a higher-level interop technology like COM.
  • Works cross-platform.

There are existing projects that enable similar scenarios, such as:

  • Unmanaged Exports
  • DllExport

Expanding System.DirectoryServices.Protocols to Linux and macOS

In this iteration, the support of cross-platform is expanded in System.DirectoryServices.Protocols. In Preview 5, the support for Linux is added, and for macOS, the support will be added in Preview 6. Support for windows was already available.

  • The System.DirectoryServices.Protocols is a lower-level API than System.DirectoryServices and enables more scenarios.
  • System.DirectoryServices includes Windows-only concepts/implementations, so it was not an obvious choice to make cross-platform.
  • Both API-sets enable controlling and interacting with a directory service server, like LDAP or Active Directory.

Alpine 3.12

The support for Alpine 3.12, for .NET Core 3.1, and .NET 5 was added in this iteration.

  • The maintainers of Alpine Linux announced the release of Alpine 3.12 on May 29th.
  • We are working on adding support for new Linux distro versions more quickly and predictably than what we have done in the past.
  • We have heard feedback that you must have access to .NET on new versions of Alpine, Debian, Ubuntu, and others as quickly as possible.

Reloadable endpoints via configuration for Kestrel

Kestrel now has the ability to observe changes to configuration passed to KestrelServerOptions.Configure and unbind from existing endpoints and bind to new endpoints without requiring you to restart your application.