Try a branchless approach for the union of two sorted arrays (array containers)

[lemire]

See blog post Faster sorted array unions by reducing branches

[richardstartin]

It seems to rely on a CMov which requires the user to set -XX:+UseCMoveUnconditionally but it looks worth experimenting with

[lemire]

This fellow seems to report that Java will use conditional moves just fine on its own...

https://ivansmirnov.wordpress.com/2015/06/14/confirmed-openjdk-jit-compiler-emits-efficient-conditional-move-machine-codes/

[lemire]

Note that the evaluation of both paths is without side-effect so I do not expect that conditional moves break the specification.

[richardstartin]

I was wrong, there is some up to date information on when cmov is used here https://shipilev.net/jvm/anatomy-quarks/30-conditional-moves/

[lemire]

I should say that whether it helps or not is tricky. If the branching is predictable, then it won't help and may even hurt us.