This blog is updated daily.
A general description is here.
The makefiles and installer scripts for Windows have been tailored to \IRtools44, an update of the \IRtools43 toolchain. It is based on GCC 13 and newer versions of \IMinGW-W64, \Ibinutils and libraries (targeting 64-bit Intel CPUs). R-devel can no longer be built using \IRtools43 without changes.
\IRtools44 has experimental suport for 64-bit ARM (aarch64) CPUs via LLVM 17 toolchain using lld, clang/flang-new and libc++.