RFR(M)(round 2): 8215902: Add support for SoftFloat-3e library

[Magnus Ihse Bursie]

Hi Jakub,

On 2019-01-15 17:31, Jakub Vaněk wrote:
> Hi Magnus and Erik,
>
> I have added the link to the repository to README and I have removed
> the link to the mailing list thread. I have also recreated the GitHub
> repository. Now it is a fork of the mentioned repository with two extra
> commits containing README and the build scripts.
>
> New webrev URL: http://cr.openjdk.java.net/~jakvanek/8215902/webrev.04/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8215902

Sorry for the late reply.

This looks very good! Thank you for fixing this, including rebasing the 
github repo.

I'm not sure if you've gotten reviews from the hotspot team for the 
hotspot source changes, but from a build perspective, this is good to go.

/Magnus
>
> Regards,
>
> Jakub
>
> On 2019-01-15 at 15:05 +0100, Magnus Ihse Bursie wrote:
>> On 2018-12-25 16:19, Jakub Vaněk wrote:
>>> Hi,
>>>
>>> please review this webrev. It is a successor of the softfloat-3
>>> [patch]
>>> thread (first email
>>>
> http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2018-November/031311.html
>>> )
>>>
>>> Changes since the last patch (v6):
>>>
>>> - renamed --with-softloat* to --with-sflt* (it is more compact and
>>> it
>>>     corresponds to the old --with-sflt-lib=... option)
>>>
>>> - license is now obtained via --with-sflt-license switch (so it is
>>> not
>>>     included in OpenJDK source tree)
>>>
>>> - updated documentation (slight rewording, added the license
>>> option)
>>>
>>> - checks for default --with/--without behavior are in place again
>>>     (I forgot them when I changed the way the library is detected)
>>>
>>> - added a simple testcase - I found a disrepancy between softfloat
>>> and
>>>     system function behavior. When a float with bits 0x003FFFFF is
>>>     added to 0x00000001, the correct result is 0x00400000, but the
>>>     default software floating point implementation returns
>>> 0x00000000.
>>>     However I'm not sure where to put this test - now it is in
>>>     test/hotspot/jtreg/compiler/floatingpoint.
>>>
>>> - comments in code refer to CR 6757269 and newly JDK-8215902 too.
>>>
>>> I have created a repository with SoftFloat-3e with build
>>> configuration
>>> specifically for OpenJDK on armel:
>>> https://github.com/ev3dev-lang-java/softfloat-openjdk
>>>
>>> I can add a link to it to the documentation.
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8215902
>>> Webrev: http://cr.openjdk.java.net/~jakvanek/8215902/webrev.02/
>> Hi Jakub,
>>
>> In general this looks good.
>>
>> Some comments:
>>
>> I agree with Erik that you can add a link to your github project;
>> compiling SoftFloat is outside the scope of the OpenJDK build
>> instructions, but it can sure be helpful to lower the bar for users
>> wanting to do that. Just one question: any particular reason you
>> didn't
>> create your github repo by forking the official
>> https://github.com/ucb-bar/berkeley-softfloat-3? That way, it would
>> have
>> been easy for users to see that you were not adding any malicious or
>> suspicious code to the original SoftFloat distribution.
>>
>> On the other hand, I think the link to
>>
> http://mail.openjdk.java.net/pipermail/aarch32-port-dev/2016-November/000611.html
>>   
>> is unnecessary and just creates clutter in the documentation. Please
>> remove it.
>>
>> /Magnus
>>> CI build:
>>> https://ci.adoptopenjdk.net/view/ev3dev/job/openjdk12_build_ev3_linux/67/
>>>
>>> Cheers,
>>>
>>> Jakub
>>>
>>