Is there a performance difference between i++ and ++i in C++?

Question

We have the question is there a performance difference between i++ and ++i in C?

What\'s the answer for C++?

Answer 1

1. ++i - faster not using the return value
2. i++ - faster using the return value

When not using the return value the compiler is guaranteed not to use a temporary in the case of ++i. Not guaranteed to be faster, but guaranteed not to be slower.

When using the return value i++ allows the processor to push both the increment and the left side into the pipeline since they don't depend on each other. ++i may stall the pipeline because the processor cannot start the left side until the pre-increment operation has meandered all the way through. Again, a pipeline stall is not guaranteed, since the processor may find other useful things to stick in.