[PATCH v4] Add support for SoftFloat library on ARM

[Jakub Vaněk]

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.
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. 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
> >  >
> >