A.5.308 SUBSD: Scalar Single-FP Subtract
SUBSD xmm1,xmm2/m128 ; F2 0F 5C /r [WILLAMETTE,SSE2]
SUBSD subtracts the low-order double-precision FP value of the source
operand from that of the destination operand, and stores the result in
the destination operation. The high quadword is unchanged.