4 ms·
This was really interesting, but one thing it didn't fully explain was why the fact that ret imm16 was fastpathed would make it a worse choice for this optimiza
by bookface 13y ago
This was really interesting, but one thing it didn't fully explain was why the fact that ret imm16 was fastpathed would make it a worse choice for this optimization than repz ret. Excuse my noobiness, but can anybody explain that to me?
- Someone 13y ago"in the K10 family, the ret imm16 instruction is now fastpathed" I understand that as follows: on the K8 both repz ret and ret imm16 were microcoded; hence, the shorter repz ret was preferred. On the K10, ret imm16 got fastpathed. That made it the preferred code, even though it is a byte longer.
- bookface 13y agoAh, thanks. I missed that that whole part was talking about the K10.