[issue2459] speedup for / while / if with better bytecode

[Antoine Pitrou]

Antoine Pitrou <pitrou at free.fr> added the comment:

Hello Collin,

Thanks for taking a look.

> I don't see the changes to the lnotab format being a roadblock; just
> mention it in NEWS. Likewise, the pure-Python compiler package shouldn't
> be a high priority; your changes to that package look good enough.

Well, I have good news: the fixes to the pure Python compiler have been
accepted and committed by Neil Schemenauer in r69373.

> I'm seeing encouraging speed-ups out of this (with gcc 4.3.1 x86_64,
> compiling Python as 64-bit):
> Django templates (render a 150x150 table 100 times):
> Min: 0.595 -> 0.589: 0.94% faster
> Avg: 0.599 -> 0.591: 1.30% faster
> 
> Spitfire templates (render a 1000x1000 table 100 times):
> Min: 0.751 -> 0.729: 2.98% faster
> Avg: 0.753 -> 0.730: 3.09% faster

Not a tremendous speedup but not totally insignificant either.
(I see you like Spitfire :-))

> None of the apps I've benchmarked are negatively impacted. I only have
> two minor comments. Please commit this.

Before committing I want to know what to do with the new jump opcodes,
with respect to the alternative proposal I've made in #4715.
Ideally, I should fold the #4715 patch back into the present patch,
since I think the #4715 approach is more thought out.

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