On Jun 30, 2018, at 8:39 AM, Martin Buchholz <martinrb@google.com> wrote:
On Sat, Jun 30, 2018 at 3:54 AM, Remi Forax <forax@univ-mlv.fr> wrote:
The other problem is more subtle, get() uses probe() and probe() uses an infinite loop and not a counted loop, the result is that c2 generates lot of assembly codes for probe() as a consequence it doesn't inline probe() in get() making get() really slow compared to HashMap.get() which is fully inlined. There are several wys to fix that: - you can try to transform the while(true) loop in probe into 2 subsequents loops from idx to length + from 0 to idx.
In ArrayDeque we had success transforming loops into 2 nested loops, the inner one being hotspot friendly, and it seems like the same approach would work for probe(). E.g. look at ArrayDeque#contains
That was my thought too. Best case is that the JIT unrolls both levels of loop. Test it though; YMMV. I like to make the outer loop iterate from false to true, as a style thing. When it unrolls you get two customized inner loops. – John