The vm receiver and argument name for v53 type is unfortunate as it's used in pair with vm package. When you have vm variable in scope, one can't access vm package.

It could be OK to rename vm to v, for example.

Simple example of shadowing is:

func (vm *v53) trace(instr vm.Instr) {
	if vm.thread().global.config.debug {
		fmt.Printf("vm @ ip=d fp=d: %v\n",
			vm.thread().frame().pc,
			vm.thread().frame().depth,
			instr,
		)
	}
}

Method gets vm receiver and refers to vm package in it's arguments list.
If function body will ever need something from that package, it would be an unpleasant experience to have.