A.5.309 SUBSS: Scalar Single-FP Subtract
SUBSS xmm1,xmm2/m128 ; F3 0F 5C /r [KATMAI,SSE]
SUBSS subtracts the low-order single-precision FP value of the source
operand from that of the destination operand, and stores the result in
the destination operation. The three high doublewords are unchanged.