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

[Vladimir Kozlov]

Okay. Lets push this version. Do you need sponsor to push?

Thanks,
Vladimir

On 3/6/19 2:25 PM, B. Blaser wrote:
> 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
>>>>