Stop the presses! 5 instructions!
vpor xmm2, xmm0, 0x80000000
vpcmpeqd xmm2, xmm1, xmm2
vcmpunordps xmm2, xmm2, xmm0
vminps xmm0, xmm1, xmm0
vblendvps xmm0, xmm0, xmm1, xmm2