Thank you for your confirmation,
I am going to read the devguide.
> On 25 oct. 2015, at 7:50 PM, Raymond Hettinger <raymond.hettin...@gmail.com>
> wrote:
>
>
>>> On Oct 25, 2015, at 12:33 PM, Raymond Hettinger
>>> <raymond.hettin...@gmail.com> wrote:
>>>
>>> On Oct 22, 2015, at 10:02 AM, Brett Cannon <br...@python.org> wrote:
>>>
>>> So my question is, the byte code generator removes the unused functions,
>>> variables etc…, is it right?
>>>
>>> Technically the peepholer removes the dead branch, but since the peepholer
>>> is run on all bytecode you can't avoid it.
>>
>> IIRC, the code was never generated in the first place (before the peephole
>> pass). This used to be true before the AST branch was added and I think it
>> may still be true.
>
> I just verified this. So Brett's post was incorrect and misleading.
>
>
> Raymond
>
>
> ----------- Verify by turning-off the optimizations ----------
> cpython $ hg diff Python/peephole.c
> diff --git a/Python/peephole.c b/Python/peephole.c
> --- a/Python/peephole.c
> +++ b/Python/peephole.c
> @@ -383,7 +383,7 @@
> /* Avoid situations where jump retargeting could overflow */
> assert(PyBytes_Check(code));
> codelen = PyBytes_GET_SIZE(code);
> - if (codelen > 32700)
> + if (codelen > 0)
> goto exitUnchanged;
>
> -------- Then run a simple disassembly -----------------------
>
> from dis import dis
>
> def f(x):
> if 0:
> print('First')
> print('Second')
>
> dis(f)
>
> -------- The output is ---------------------------------------------------
>
> $ py tmp.py
> 6 0 LOAD_GLOBAL 0 (print)
> 3 LOAD_CONST 1 ('Second')
> 6 CALL_FUNCTION 1 (1 positional, 0 keyword pair)
> 9 POP_TOP
> 10 LOAD_CONST 0 (None)
> 13 RETURN_VALUE
>
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