On Wed, Jul 22, 2020 at 3:43 AM Mark Shannon <[email protected]> wrote:
>
> On 18/07/2020 9:20 am, Inada Naoki wrote:
> > It seems great improvement, but I am worrying about performance.
> >
> > Adding more attributes to the code object will increase memory usage
> > and importing time. Is there some estimation of the overhead?
>
> Zero overhead (approximately).
> We are just replacing one compressed table with another at the C level.
> The other attributes are computed.
>
> >
> > And I am worrying precise tracing blocks future advanced bytecode
> > optimization.
> > Can we omit precise tracing and line number information when
> > optimization (`-O`) is enabled?
>
> I don't think that is a good idea.
> Performing any worthwhile performance optimization requires that we can
> reason about the behavior of programs.
> Consistent behavior makes that much easier.
> Inconsistent "micro optimizations" make real optimizations harder.
>
> Cheers,
> Mark.
>
Tracing output is included in the program behavior?
For example, if two code block is completely equal:
if a == 1:
very very
long
code block
elif a == 2:
very very
long
code block
This code can be translated into like this (pseudo code):
if a == 1:
goto block1
if a == 2:
goto block1
block1:
very very
long
code block
But if we merge two equal code blocks, we can not produce precise line
numbers, can we?
Is this inconsistent microoptimization that real optimization harder?
This optimization must be prohibited in future Python?
Regards,
--
Inada Naoki <[email protected]>
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