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

[Vladimir Kozlov]

Hi Bernard,

I don't see updated patch. I will run more testing on it after I get it (jdk/submit only runs tier1 testing).

Thanks,
Vladimir

On 2/27/19 8:42 AM, B. Blaser wrote:
> On Tue, 26 Feb 2019 at 22:34, Vladimir Kozlov
> <vladimir.kozlov at oracle.com> wrote:
>>
>> On 2/26/19 1:14 PM, B. Blaser wrote:
>>> Hi Vladimir,
>>>
>>> On Tue, 26 Feb 2019 at 21:50, Vladimir Kozlov
>>> <vladimir.kozlov at oracle.com> wrote:
>>>>
>>>> Hi Bernard,
>>>>
>>>> Unfortunately HotSpot does not collect profiling information per call site.
>>>> Currently calee's data is collected from all call sites. For example, you can have 2 calls with same *swapped* arguments
>>>> and you will get your balance == 0.
>>>> I would assume if you have multiply call sites in application the profiling data will be "flat" - balance value will be
>>>> near 0.
>>>>
>>>> We did experiment few years ago to collect data per call site but we got negative result - no significant improvement in
>>>> code quality in cost of a lot more memory used for MethodData.
>>>> But your case (and cmove) is special since MDO is small for these methods. The only downside is to implement that you
>>>> will need a lot more complex changes in HotSpot.
>>>>
>>>> https://bugs.openjdk.java.net/browse/JDK-8015416
>>>>
>>>> Note, your code is correct in a sense that it use the same profiling data as it currently used for inlining these
>>>> methods. So I don't want to reject changes from the start.
>>>>
>>>> The only simple solution I can think of is to use intrinsic only for hottest call site. Compare invocation_count with
>>>> caller's call site count to find if it is most used site which contributed the most profiling data.
>>>>
>>>> Thanks,
>>>> Vladimir
>>>
>>> Thanks for your feedback.
>>>
>>> I pushed webrev.05 to jdk/submit a while ago but once I have the
>>> results I'll update the patch as you suggested; the heuristic will
>>> bail out if the caller didn't contribute enough to the statistics, let
>>> say something like at least 80%?
>>
>> Yes, this sounds good.
>>
>> Vladimir
> 
> Done: http://hg.openjdk.java.net/jdk/submit/rev/d164e0b595e6
> 
> Please let me know if you've any more comments or if I can push this
> to the main-line (jdk/jdk) once I've got positive test results?
> 
> Thanks,
> Bernard
>