[PATCH v4] Add support for SoftFloat library on ARM

[Boris Ulasevich]

Hi Jakub,

Please see comments inline.
And one more point: please remove links to mail threads from sources (http://mail.openjdk.java.net/pipermail/aarch32-port-dev/2016-November/000611.html).

Boris

12.12.2018 17:36, Jakub Vaněk пишет:
> Hi Erik,
>
> On 2018-12-12 at 15:41 +0300, Boris Ulasevich wrote:
>> Hi Jakub,
>>
>> I do not understand why you use memcpy in softfloat_arm.cpp.
>> If type cast is the only reason why don't you use reinterpret_cast?
>>
>> regards,
>> Boris
> I'm using memcpy there because float32_t is a struct containing a
> single uint32_t member. I think that the proper way of doing a byte-
> level conversion between different types (type punning) is via memcpy.
Do not you expect performance penalty using type conversion this way?
> If I used a casted pointer, this would violate the rule that I can
> access a memory location through a pointer of only one type.

-fno-strict-aliasing gcc option is used to disable compiler complains on 
this rule:

jdk-jdk/make/hotspot/lib/JvmFeatures.gmk:  JVM_LDFLAGS_FEATURES += 
-fno-strict-aliasing

> Using
> union for this seems to be also undefined in C++, as then I would
> access the value through a non-active member.
>
> Thanks,
>
> Jakub
>
>> On 10.12.2018 23:23, Jakub Vaněk wrote:
>>> Hi Erik,
>>>
>>> On 2018-12-10 at 09:39 -0800, Erik Joelsson wrote:
>>>> The build changes look ok to me.
>>>>
>>>> I do think --enable-softfloat is redundant as using any of the
>>>> other
>>>> parameters would imply it to be set, but it's ok to have it
>>>> there.
>>> Thanks for the review. The motivation for this was that I was
>>> closely
>>> following how libffi is handled. The enable option was a workaround
>>> for
>>> the detection of softfloat in system paths. I don't think this is
>>> how
>>> the library is going to be used, so I removed this option.
>>>
>>> New patch can be found here:
>>> https://github.com/ev3dev-lang-java/openjdk-ev3/blob/78a9d35986ed51273d9a3bb9878cbfcbe2488bfb/upstream/softfloat.patch
>>>
>>> Regards,
>>>
>>> Jakub
>>>
>>>> /Erik
>>> < raw patch at
>>> https://raw.githubusercontent.com/ev3dev-lang-java/openjdk-ev3/78a9d35986ed51273d9a3bb9878cbfcbe2488bfb/upstream/softfloat.patch
>>>   >
>>>