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

[Magnus Ihse Bursie]

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
>