> Ah yeah, I wasn't sure if fusion was going to happen. Well, I didn't profile that case. Who knows what will really happen. Modern x86 processors are hard to

> Ah yeah, I wasn't sure if fusion was going to happen. Well, I didn't profile that case. Who knows what will really happen. Modern x86 processors are hard to understand. > ... while the second cmp is against memory, data dependent on the register index Hmm... that sounds like something that would dominate the cost? Memory access and data dependency. Ouch. Also of course in that case, second compare+branch can't be fused, because cmp has a memory operand.