DMD outputs xchg RDX, RAX when you ask for xchg RDX, R8

/// CODE:

ulong bug(ulong a, ulong b, ulong c)
{
	version (D_InlineAsm_X86_64)
	{
	// RDI = c RSI = b RDX = a
	// RAX = return value
	// Scratch: RAX, RCX, R8, R9
	version (linux)
	asm
	{
		naked;
		// Let's return c using iasm
		mov RAX, RDI;
		// DMD outputs: REX.W+90+rd XCHG r64, RAX
		// instead of: REX.W+87/r XCHG r/m64,r64
		xchg RDX, R8;
		// Interestingly, DMD outputs:
		//		xchg RDX,RDI
		//	and	xchg RDX,R9 correctly
		ret;
	}
	}
}


ulong nobug(ulong a, ulong b, ulong c)
{
	version (D_InlineAsm_X86_64)
	{
	version (linux)
	asm
	{
		naked;
		mov RAX, RDI; // Let's return c using iasm
		db 0x4c; db 0x87; db 0xC2; // xchg RDX, R8;
		ret;
	}
	}
}

void main()
{
	import std.stdio;
	writeln(bug(1, 2, 3));   // ERROR: outputs 1
	writeln(nobug(1, 2, 3)); // outputs 3 as it should
	assert(bug(1, 2, 3) == 3);// should pass but fails
}