[pypy-dev] Work on the JVM backend

[Antonio Cuni]

Hello Michał,

On 01/16/2012 01:00 AM, Michał Bendowski wrote:
> longlong2float and float2longlong turn out to be pretty straightforward in Java, so I implemented them and added tests. I tried to update the pull request to include this commit, but that crashed BitBucket :/ Maybe you can just pull it from my repo?

I reviewed your pull request. A few notes:

1. float2longlong & longlong2float can be implemented in a more direct way by 
using Double.doubleToRawLongBits and Double.longBitsToDouble

2. in revision 25d4d323cb5f, you implemented _identityhash of builtin types by 
returning hash(self). This is wrong, because as the name suggests, it needs to 
return different hashes for objects which are not identical. For example, look 
at the following code:

     >>> from pypy.rlib import objectmodel
     >>> a = 'foo'
     >>> b = 'f'; b += 'oo'
     >>> a == b
     True
     >>> a is b
     False
     >>> objectmodel.compute_identity_hash(a)
     192311087
     >>> objectmodel.compute_identity_hash(b)
     -1955336075

The test should probably try to compute_unique_id of two strings which are
equal but not identical, and check that they are different

3. could you please transplant your checkins to some branch other than 
default, e.g. jvm-improvements? This way I could just merge the pull request 
and then run the test on buildbot, before doing the actual merge to default.

Apart from this, your patch looks very good :-)

ciao&thanks,
Antonio