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GNUstep Objective-C Runtime 2.2
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@davidchisnall davidchisnall released this 04 Feb 08:52
· 26 commits to master since this release
v2.2
7c2ecce

This is the second update to the second major release of the GNUstep Objective-C
runtime (a.k.a. libobjc2). This runtime was designed to support the features
of modern dialects of Objective-C for use with GNUstep and other Objective-C
programs.

Highlights of this release include:

  • Initial support for RISC-V 64-bit (rv64) including an architecture-specific
    objc_msgSend, and block trampoline implementation. Please note that
    double-precision floating-point support (rv64d) is required for the
    objc_msgSend implementation.
  • Initial support for Windows on ARM64 with fast-path objc_msgSend.
  • Numerous improvements to the Objective-C++ exception interoperation code.
    The runtime now dynamically detects whether the libcxxrt, libsupc++, or
    libc++abi variant of the Itanium C++ Exception ABI is being used. This is
    the first version to support exception interoperability with libc++abi.
  • Because we no longer need to identify the specific C++ runtime, we can link
    to it indirectly via the C++ standard library, which enables more C++ to be
    used in the Objective-C runtime.
  • The minimum CMake version has been bumped to 3.16, which supports
    Objective-C. This support is now used, simplifying the build.
  • Support for GC mode is gone. Apple dropped support for this a long time ago.
  • objc_setUncaughtExceptionHandler is added, which avoids consuming code
    needing to access a library-owned global.
  • The selector-table code has been rewritten in C++, improving performance of
    adding selectors. This is unlikely to have a measurable impact on
    performance outside of contrived test cases, but the new code is more
    maintainable.
  • Several bug fixes in the ARC code, especially in corner cases surrounding
    weak references.
  • Support for fast-path allocation / initialisation functions. Root classes
    that opt into this should implement +_TrivialAllocInit (this can be an
    empty method, it is not called). Clang 18 or later will emit calls to the
    fast-path functions for +alloc, +allocWithZone: and +alloc + -init
    calls. This should improve code density as well as performance.

You may obtain the code for this release from git and use the 2.2 branch:

https://github.com/gnustep/libobjc2.git

Alternatively, a tarball is available from:

https://github.com/gnustep/libobjc2/archive/v2.2.zip
https://github.com/gnustep/libobjc2/archive/v2.2.tar.gz

The runtime library is responsible for implementing the core features of the
object model, as well as exposing introspection features to the user. The
GNUstep runtime implements a superset of Apple's Objective-C Runtime APIs.

If you come across any problems, please file them in the issue tracker:

https://github.com/gnustep/libobjc2/issues

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