What's with this strange desire to mandate One True Way to implement function calls in every language implementation? If I want to use rbx/r11/r10/r9 for argument passing and return results in rdx/rsi by default and have to use

     @if os.LINUX and cpu.X64
     import external func[[regseq("rdi,rsi,rdx,rcx|rax"), library("libc.so")]] fwrite(buff ptr, size int64, count int64, stream ptr) int64;
     @endif