Comment by saagarjha

    %macro stackpush 0
        push rdi
        push rsi
        push rdx
        push r10
        push r8
        push r9
        push rbx
        push rcx
    %endmacro
    
    %macro stackpop 0
        pop rcx
        pop rbx
        pop r9
        pop r8
        pop r10
        pop rdx
        pop rsi
        pop rdi
    %endmacro

I guess that's one way of saving registers. Not particularly efficient, I guess, but it works…