https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124074
--- Comment #2 from John Platts <john_platts at hotmail dot com> --- Correction: In addition, Microsoft has made some changes to the x86-64 calling convention for Win64 which makes R16-R29 volatile (which do not need to be saved by the callee) and R30-R31 nonvolatile (which need to be saved by the callee prior to use) on x86-64 systems supporting APX, which is described at https://learn.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170.
