[Python-Dev] Python 3 optimizations continued...

[Cesare Di Mauro]

2011/9/1 Mark Shannon <mark at hotpy.org>

> Cesare Di Mauro wrote:
>
>> 2011/9/1 Ned Batchelder <ned at nedbatchelder.com <mailto:
>> ned at nedbatchelder.com>>
>>
>>
>>    When the switchover to the new instruction format happens, what
>>    happens to sys.settrace() tracing?  Will it report the same sequence
>>    of line numbers?  For a small but important class of program
>>    executions, this is more important than speed.
>>
>>     --Ned
>>
>>
>> A simple solution: when tracing is enabled, the new instruction format
>> will never be executed (and information tracking disabled as well).
>>
>>  What happens if tracing is enabled *during* the execution of the new
> instruction format?
> Some sort of deoptimisation will be required in order to recover the
> correct VM state.
>
> Cheers,
> Mark.
>

Sure. I don't think that the regular ceval.c loop will be "dropped" when
executing the new instruction format, so we can "intercept" a change like
this using the "why" variable, for example, or something similar that is
normally used to break the regular loop execution.

Anyway, we need to take a look at the code.

Cheers,
Cesare
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