% cat test.d
void foo(lazy ulong x) {}
void main(string[] args)
{
	foo(args.length);
}

admin@poita ~% dmd -inline -O -release test.d
admin@poita ~% otool -tV test | grep __Dmain: -A 9
__Dmain:
0000000100000dac	pushq	%rbp
0000000100000dad	movq	%rsp,%rbp
0000000100000db0	subq	$0x10,%rsp
0000000100000db4	movq	%rdi,0xf0(%rbp)
0000000100000db8	movq	%rsi,0xf8(%rbp)
0000000100000dbc	xorl	%eax,%eax
0000000100000dbe	movq	%rbp,%rsp
0000000100000dc1	popq	%rbp
0000000100000dc2	ret

Notice the redundant movq's. They aren't there when the parameter isn't lazy.

Ideally, this empty function would have no effect on the generated code.

Tested using DMD 2.060