AVX has a four-operand VBLENDVPD instruction, which allows for the first
input and the destination to be different. By taking advantage of this,
we no longer need to copy one of the inputs around and we can just
reference it directly, provided it's already in a register (I have yet
to see this not be the case).
Before:
66 0F 57 C0 xorpd xmm0,xmm0
F2 41 0F C2 C6 06 cmpnlesd xmm0,xmm14
41 0F 28 CE movaps xmm1,xmm14
66 41 0F 38 15 CA blendvpd xmm1,xmm10,xmm0
F2 44 0F 10 F1 movsd xmm14,xmm1
After:
66 0F 57 C0 xorpd xmm0,xmm0
F2 41 0F C2 C6 06 cmpnlesd xmm0,xmm14
C4 C3 09 4B CA 00 vblendvpd xmm1,xmm14,xmm10,xmm0
F2 44 0F 10 F1 movsd xmm14,xmm1
a52774ca63