Using a java port of fdlibm on the hsail backend

[Christian Thalinger]

On May 8, 2014, at 12:03 PM, Joe Darcy <joe.darcy at oracle.com> wrote:

> Hello,
> 
> The C code in fdlibm is written in a very particular style. I don't trust many people to do the port; I happen to be one of the people I trust to do this ;-)
> 
> Reviewing someone else's port of this code would be an effort on par with doing the port myself, so I prefer to do the port myself. I intend to do this port in 9 (this time for real!).

Hear! Hear!  Thank you, I really appreciate this.  If there is anything I can help with, let me know.

> Having this code in Java will reduce our exposure to C compiler vagaries when upgrade compilers or port Java to new platforms. (The C code in fdlibm uses long / double aliasing and thus runs afoul of most optimizers.)
> 
> HTH,
> 
> -Joe
> 
> On 05/08/2014 06:23 AM, Azeem Jiva wrote:
>> Joe and I have talked about this on and off for quite some time.  I’ve CCed him to see what his current thoughts are on this.
>> 
>> 
>> On May 7, 2014, at 8:41 PM, Tom Rodriguez <tom.rodriguez at oracle.com> wrote:
>> 
>>> On May 7, 2014, at 7:35 PM, Christian Thalinger <christian.thalinger at oracle.com> wrote:
>>> 
>>>> On May 7, 2014, at 10:43 AM, Doug Simon <doug.simon at oracle.com> wrote:
>>>> 
>>>>> Given that it was contributed under an OCA, I don’t see why we couldn’t use. However, otherwise with more legal knowledge can confirm that.
>>>>> 
>>>>> I wonder why there was no interest shown in this contribution on the hotspot-dev mailing list. It makes me wonder if the Java port is really 100% compliant.
>>>> This was a long time ago and I’m also curious why there was no interest.
>>> From the hotspot side fdlibm is a solved problem.  Replacing it with a Java version might be better in some ways but it perturbs the universe without much clear upside.  It also introduces maintenance concerns since fdlibm is fairly broadly used but the Java version probably isn’t.
>>> 
>>> Joe Darcy would be the one to ask about the quality of the Java port.  If it were ever adopted by the JDK he would also likely be the one to do it.
>>> 
>>> tom
>>> 
>>>> Anyway, I filed a tracking bug because we didn’t have one:
>>>> 
>>>> [#JDK-8042716] Java port of fdlibm 5.3 to java.lang.StrictMath - Java Bug System
>>>> 
>>>>> -Doug
>>>>> 
>>>>> On May 7, 2014, at 8:56 PM, Deneau, Tom <tom.deneau at amd.com> wrote:
>>>>> 
>>>>>> Sending to Azeem representing the hotspot team and to the graal team...
>>>>>> 
>>>>>> On the hsail backend, we would like to implement the various java.lang.Math routines and we need a solution that is completely hsail, since we can't call out to any  host C routines.  An easy solution for us would be to use a java implementation of java.lang.Math.  I saw this mail back in the hotspot-dev archives describing a port of FDLIBM to Java which looked promising.
>>>>>> 
>>>>>> http://mail.openjdk.java.net/pipermail/hotspot-dev/2009-August/001992.html
>>>>>> 
>>>>>> I have tried the sin() routine out of this port in the hsail backend and it seems to work well functionally and performance-wise.
>>>>>> 
>>>>>> Is there any problem with using this code as part of the graal project as @MethodSubstitutions?
>>>>>> 
>>>>>> -- Tom Deneau
>>>>>> 
>