On 18 Jul., 01:15, castironpi <castiro... at gmail.com> wrote:
> On Jul 17, 5:37 pm, I V <ivle... at gmail.com> wrote:
>
>
>
> > On Thu, 17 Jul 2008 15:08:17 -0700, castironpi wrote:
> > > The Python disassembly is baffling though.
>
> > >>>> y= 3
> > >>>> dis.dis('x=y+1')
>
> > You can't disassemble strings of python source (well, you can, but, as
> > you've seen, the results are not meaningful). You need to compile the
> > source first:
>
> > >>> code = compile('y=x+1','-', 'single')
> > >>> dis.dis(code)
>
> > 1 0 LOAD_NAME 0 (x)
> > 3 LOAD_CONST 0 (1)
> > 6 BINARY_ADD
> > 7 STORE_NAME 1 (y)
> > 10 LOAD_CONST 1 (None)
> > 13 RETURN_VALUE
>
> > You may well find these byte codes more meaningful. Note that there is a
> > list of opcodes athttp://docs.python.org/lib/bytecodes.html
>
> Oh. How is the stack represented?
As a pointer to a pointer of PyObject structs.
> Does it keep track of which stack
> positions (TOS, TOS1, etc.) are in what registers? Does stack
> manipulation consume processor cycles?
Python does not store values in registers. It stores locals in arrays
and accesses them by position ( you can see the positional index in
the disassembly right after the opcode name ) and globals / object
attributes in dicts.
For more information you might just download the source distribution
and look for src/Python/ceval.c. This file contains the main
interpreter loop.