JIT code generation for Long/Integer.compare

[Vladimir Kozlov]

Chuck has OpenJDK id (he is jdk9 Reviewer!) and can create JBS entry for 
you and also put your *webrev* on cr. server. Please, ask him.

We will help with reviews and push.

Regards,
Vladimir

On 9/25/15 2:45 AM, Ian Rogers wrote:
> Below is a patch to add JIT code generation for Long/Integer.compare. It
> has been reviewed internally by rasbold at google.com
> <mailto:rasbold at google.com>. I'd like to open a bug for this, get it
> reviewed, etc. but I lack a JBS account. I'd appreciate help in getting
> this reviewed and merged.
>
> Thanks,
> Ian Rogers
>
> Support JIT code generation for Long/Integer.compare as intrinsics that
> fold with branches on their result.
>
> Introduce a CmpI3 ideal node mirroring the CmpL3 node, that implements
> Integer.compare. Allow this to fold with a CmpI node.  Spot
> Long/Integer.compare
> as CmpL3 and CmpI3 nodes.  Add a CmpI3 implementation for x86-64.  On a
> micro-benchmark loop of:
>      for (int i = 0; i < x.length; i++) {
>        if (compare(x[i], y[i]) < 0) {
>          count++;
>        }
>      }
> Int speed up averages 1.18x, long speed up averages 2.76x, over 30 runs of
> arrays sized at 5,000,000 elements. This can be improved with work on
> instruction selection.
> Raw data:
> Int before:  23129us, 99.5% range: 19935us - 26046us
> Int after:   19557us, 99.5% range: 16972us - 26072us
> Long before: 26935us, 99.5% range: 25776us - 29323us
> Long after:   9749us, 99.5% range: 8850us  - 11968us
>