The first release candidate of LLVM 21.1 is now available for testing, which under their modern versioning scheme will represent the first stable version of the LLVM 21 compiler stack.
As noted earlier this week when LLVM 21 was branched and LLVM 22 now open for development, the LLVM 21.1 series is going to bring a lot of notable additions and refinements to existing functionality for this half-year compiler update. LLVM 21 introduces the AMD GFX1250 target for what is expected to be an APU with an RDNA4 refresh (RDNA 4.5?) while the additions for the GFX1250 target remain ongoing. There are also other AMDGPU LLVM back-end enhancements for helping their ROCm stack and other libc-for-GPU efforts. There is also now -mcpu=gb10 support for NVIDIA’s GB10 Superchip, various RISC-V improvements, many RISC-V back-end enhancements, LLDB debugger improvements, and more.
On the Clang 21 C/C++ compiler front-end side there are new LLVM optimizations around pointer arithmetic on null pointers, new C++2c feature additions, various other C++ language features added, new C warnings, additional C2y feature work, and many compiler diagnostic enhancements. Clang 21 also addresses Intel’s changes to AVX10 with dropping the AVX10-256 support to now make 512-bit support unconditional for the maximum vector register size.
The brief LLVM 21.1-rc1 release announcement can be read via the LLVM Discourse. Testing of LLVM 21.1 will continue until the LLVM 21.1.0 stable release is ready in about six weeks — a late August or early September debut.
