[pypy-dev] Slow int code

[Maciej Fijalkowski]

import sys
print sys.maxint

On Mon, Mar 4, 2013 at 10:42 AM, Roger Flores <aidembb at yahoo.com> wrote:
> On March 3, 2013 2:20 AM, Carl Friedrich Bolz wrote:
>>Are you *sure* you are running on a 64 bit machine?
>
> Sure?  No.  I assumed it's 64bit pypy because it was generating x86_64 instructions.  How would you check for sure?
>
> uname reports x86_64 on the machine I built pypy on.
>
> $ pypy --version
> Python 2.7.3 (42c0d1650cf4, Feb 23 2013, 01:53:42)
> [PyPy 2.0.0-beta1 with GCC 4.6.3]
>
> That doesn't show the machine size.
>
> pypy --info is interesting but doesn't help either
>
> ?
>
>
>>When I run diz.py on a 64 bit machine, the BINARY_XOR bytecodes turn into int_xor low
> level operations, as expected.
>
> I would like to see what you see using jitviewer since it differs from what I pasted (and maybe to figure out why).
>
>
>
>>Anyway, to debug where low and high turn into Python longs, you can putthe following properties in arithmetic32.Encoder:
> ...
>
> That was some clever code. I like it. :)
>
>
>> In 32 bit they obviously trigger because of the line self.low = (self.low << 1) & 0xffffffff
> (0xffffffff is a Python long on 32 bit).
>
> Specifically it's a long because 0xffffffff is unsigned 32 bit and thus can't fit in a signed 32bit.  There no hope for the 32 bit version unless more int types are added beyond Python's two, specifically an uint32 type.  And that's not python.  Except, I did notice that numpy has this type and more:
>
> https://github.com/numpy/numpy/blob/master/numpy/core/include/numpy/npy_common.h
>
> It's conceivable that the efforts to bring numpy into pypy will be dealing with these various int sizes and could better support uint32 code like that in diz.  However, I suspect it's not a huge win because the int operations will remain function calls instead of single x86 instructions.  That's the real pain, on all platforms.
>
>
> Anyways, I run the code and it works.  Everywhere.  And I've finally convinced myself to stop abusing the dict with millions of items, so I've got more stuff to do. :)
>
>
>
> -Roger
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