[Patches] [ python-Patches-427190 ] Speed-up "O" calls

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Patches item #427190, was updated on 2001-05-24 22:30
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Category: core (C code)
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Martin v. Löwis (loewis)
Assigned to: Jeremy Hylton (jhylton)
>Summary: Speed-up "O" calls

Initial Comment:
This patch improves the performance of a few functions
which have an "O" signature (ord, len, and
list_append). On selected test cases, this patch gives
a speed-up of 40%. If accepted, the approach can be
extended to more signatures. E.g. "l" is already
provided in the patch, but currently not used.

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>Comment By: Jeremy Hylton (jhylton)
Date: 2001-06-01 08:14

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Just took a quick look -- looks good.  

One question: Why does METH_NOARGS call the method with two
arguments where the second is always NULL?  Wouldn't it be
clearer to have these functions take one argument?


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Comment By: Martin v. Löwis (loewis)
Date: 2001-06-01 07:34

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I rewrote the patch to only support METH_NOARGS and METH_O,
and to not use bit masks for them.

I also changed calling conventions for all Object operations
and bltin and sys functions. In the course of these changes,
two functions got a changed meaning:
- file.writelines accepts only exactly one argument
- iter.next does not accept any arguments anymore

As you can see in the patch,there is still a lot of places
that continue to use OLDARGS (plus all the Modules functions
that have not been changed in this patch), so OLDARGS will
be needed for quite some time.

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Comment By: Jeremy Hylton (jhylton)
Date: 2001-05-29 13:59

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I like METH_O, but I'm not sure about METH_L.  I'd rather
see the call handling in ceval be type-neutral.  It's easy
enough for the callee to cast from an object to an int (or
any other type).  There should be no effect on performance
and it reduces the amount of code in the core.

I think the implementation could be simplified a lot if it
defined METH_O -- or perhaps METH_NOARGS,  METH_ONEARG, and
maybe even METH_TWOARGS (but Tim has a pretty good argument
against that one).  I don't think there's any define METH_O
via METH_SPECIAL and reserve all of 0xFFF0 for flags on
METH_SPECIAL.  Instead, I'd just use the next N bits to
implement the next N flags.

The SPECIALSIZE and extra stack used in the implementation
seem like unneeded generality, too.  If the implementation
is only going to support 0 and 1 (and possibly 2) argument,
there's no need for anything more general.

Finally, I suggest appropriating fast_cfunction() for this
purpose, rather than calling the new function
do_call_special(), where "special" isn't a very specific
meaning.  If METH_NOARGS and METH_ONEARG are implemented,
there is basically no reason to use METH_OLDARGS.  So we can
get rid of it in the code base and stop attempting to
optimize it.

Do you want to have a go at a smaller patch that just did
METH_ONEARG and METH_NOARGS?


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