LLVM 21.0.0git Release Notes

Warning

These are in-progress notes for the upcoming LLVM 21.0.0git release. Release notes for previous releases can be found on the Download Page.

Introduction

This document contains the release notes for the LLVM Compiler Infrastructure, release 21.0.0git. Here we describe the status of LLVM, including major improvements from the previous release, improvements in various subprojects of LLVM, and some of the current users of the code. All LLVM releases may be downloaded from the LLVM releases web site.

For more information about LLVM, including information about the latest release, please check out the main LLVM web site. If you have questions or comments, the Discourse forums is a good place to ask them.

Note that if you are reading this file from a Git checkout or the main LLVM web page, this document applies to the next release, not the current one. To see the release notes for a specific release, please see the releases page.

Non-comprehensive list of changes in this release

  • …

Changes to the LLVM IR

  • The nocapture attribute has been replaced by captures(none).

  • The constant expression variants of the following instructions have been removed:

    • mul

Changes to LLVM infrastructure

  • Removed support for target intrinsics being defined in the target directories themselves (i.e., the TargetIntrinsicInfo class).

Changes to building LLVM

Changes to TableGen

Changes to Interprocedural Optimizations

Changes to the AArch64 Backend

Changes to the AMDGPU Backend

Changes to the ARM Backend

Changes to the AVR Backend

Changes to the DirectX Backend

Changes to the Hexagon Backend

Changes to the LoongArch Backend

Changes to the MIPS Backend

Changes to the PowerPC Backend

Changes to the RISC-V Backend

Changes to the WebAssembly Backend

Changes to the Windows Target

Changes to the X86 Backend

Changes to the OCaml bindings

Changes to the Python bindings

Changes to the C API

  • The following functions for creating constant expressions have been removed, because the underlying constant expressions are no longer supported. Instead, an instruction should be created using the LLVMBuildXYZ APIs, which will constant fold the operands if possible and create an instruction otherwise:

    • LLVMConstMul

    • LLVMConstNUWMul

    • LLVMConstNSWMul

Changes to the CodeGen infrastructure

Changes to the Metadata Info

Changes to the Debug Info

Changes to the LLVM tools

Changes to LLDB

  • When building LLDB with Python support, the minimum version of Python is now 3.8.

  • LLDB now supports hardware watchpoints for AArch64 Windows targets. Windows does not provide API to query the number of supported hardware watchpoints. Therefore current implementation allows only 1 watchpoint, as tested with Windows 11 on the Microsoft SQ2 and Snapdragon Elite X platforms.

  • LLDB now steps through C++ thunks. This fixes an issue where previously, it wouldn’t step into multiple inheritance virtual functions.

Changes to lldb-dap

  • Breakpoints can now be set for specific columns within a line.

Changes to BOLT

Changes to Sanitizers

Other Changes

External Open Source Projects Using LLVM 21.0.0git

  • A project…

Additional Information

A wide variety of additional information is available on the LLVM web page, in particular in the documentation section. The web page also contains versions of the API documentation which is up-to-date with the Git version of the source code. You can access versions of these documents specific to this release by going into the llvm/docs/ directory in the LLVM tree.

If you have any questions or comments about LLVM, please feel free to contact us via the Discourse forums.