[PATCH] 8217561 : X86: Add floating-point Math.min/max intrinsics, approval request

[B. Blaser]

Here it is:

http://cr.openjdk.java.net/~bsrbnd/jdk8217561/webrev.06/

Any feedback is welcome (jdk/submit report is good),
Bernard

On Wed, 6 Mar 2019 at 20:57, B. Blaser <bsrbnd at gmail.com> wrote:
>
> Hi Vladimir,
>
> I'd like to keep branch predictions commented out until method data is
> collected per call-site because current statistics aren't accurate
> enough to really improve the following numbers.
>
> I tried Math.min(float) with the current patch [1] on both standard
> and reduction scenarios [2] for negative zero, zero, constant and
> random arrays (NaN being rather uncommon). I had to make an average
> between min(a,b) and its mirror min(b,a) for reductions because of the
> asymmetrical API implementation.
>
> To summarize:
>
>               |            pattern          |          array          |
>               | blend/min/max | one ucomisd | +/-0.0 | const | random |
> --------------|---------------|-------------|--------|-------|--------|
> predictable   |    8% gain    |   unused    |  yes   |  yes  |  no    |
> unpredictable |   57% gain    |   unused    |  no    |  no   |  yes   |
> reduction     |    unused     |  25% gain   |  yes   |  yes  |  yes   |
>
> We see that the suggested fix to use 'ucomisd' for reductions and
> 'blend/min/max' otherwise is always faster than before. I'll prepare
> the final webrev based on all JDK-8217561 changesets very soon.
>
> Thanks,
> Bernard
>
> [1] http://hg.openjdk.java.net/jdk/submit/log?rev=branch%28%22JDK-8217561%22%29
> [2] http://hg.openjdk.java.net/jdk/submit/file/ab2b1418f0db/test/micro/org/openjdk/bench/vm/compiler/FpMinMaxIntrinsics.java
>
>
> On Wed, 6 Mar 2019 at 19:03, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
> >
> > Hi Bernard,
> >
> > Can you prepare final patch for review? Changesets are good to see incremental changes but I already lost what whole
> > changes are.
> >
> > Also in latest changeset branch prediction code in library_call.cpp is commented. Is this what you want in final changes?
> >
> > Thanks,
> > Vladimir
> >
> > On 3/4/19 1:15 PM, B. Blaser wrote:
> > > On Sat, 2 Mar 2019 at 20:51, Bhateja, Jatin <jatin.bhateja at intel.com> wrote:
> > >>
> > >> Having multiple selection patterns based on node properties is good if we have
> > >> optimized selection patterns with and without properties (in this case reduction)
> > >
> > > Pushed to jdk/submit as third changeset on branch JDK-8217561:
> > >
> > > http://hg.openjdk.java.net/jdk/submit/rev/9aa98249f99c
> > >
> > > I think this is our best solution, could we have a Reviewer feedback
> > > for this (hotspot:tier1 is OK on x86_64 xeon)?
> > >
> > > Thanks,
> > > Bernard
> > >