A.5.306 SUBPD: Packed Double-Precision FP Subtract
SUBPD xmm1,xmm2/m128 ; 66 0F 5C /r [WILLAMETTE,SSE2]
SUBPD subtracts the packed double-precision FP values of the source
operand from those of the destination operand, and stores the result in
the destination operation.