JIT code generation for Long/Integer.compare

[Ian Rogers]

Agreed. The attached patch eliminates the cmpl3_flag enc_class and
implements both cmpl3 and cmpi3 as you suggest.

Thanks,
Ian

On Thu, Sep 24, 2015 at 12:51 PM, Christian Thalinger <
christian.thalinger at oracle.com> wrote:

> One comment about the .ad change:  please don’t introduce new enc_class
> methods; use ins_encode %{ %} and MacroAssembler instructions instead, like
> this one:
>
>   ins_encode %{
>     Register Rp = $p$$Register;
>     Register Rq = $q$$Register;
>     Register Ry = $y$$Register;
>     Label done;
>     __ cmpl(Rp, Rq);
>     __ jccb(Assembler::less, done);
>     __ xorl(Ry, Ry);
>     __ bind(done);
>   %}
>
> Should be less painful too :-)
>
> On Sep 24, 2015, at 8:45 AM, Ian Rogers <irogers at google.com> wrote:
>
> Below is a patch to add JIT code generation for Long/Integer.compare. It
> has been reviewed internally by 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
>
> <cmpi3-jdk9-tdiff.patch>
>
>
>
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