Changes by Collin Winter coll...@gmail.com:
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nosy: +collinwinter
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Terry J. Reedy tjre...@udel.edu added the comment:
Martin, I agree that we would have to think carefully about all
attributes of all constants loaded by LOAD_CONST, and about
special-casing marshal, but given that 'str' object attribute 'join' is
read-only, how is ''.join not a constant? Do you
Raymond Hettinger rhettin...@users.sourceforge.net added the comment:
I'm working a better patch now. Will give to collin to review when it's
ready. Here's a draft of the new opcode:
TARGET(LOAD_CONST_ATTR)
u = GETLOCAL(oparg);/* Cached attribute or
Raymond Hettinger rhettin...@users.sourceforge.net added the comment:
Attaching a rough patch for caching constant attribute lookups. Has an
open TODO for adding the new name to co-co_varnames.
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Added file: http://bugs.python.org/file14115/constattr.diff
Martin v. Löwis mar...@v.loewis.de added the comment:
Terry J. Reedy wrote:
Terry J. Reedy tjre...@udel.edu added the comment:
Martin, I agree that we would have to think carefully about all
attributes of all constants loaded by LOAD_CONST, and about
special-casing marshal, but given that
Terry J. Reedy tjre...@udel.edu added the comment:
You are right, of course: bound methods are currently created fresh on
each access, even though each is equal except for identity. I was
thinking in terms of
str.join is str.join
True
This appears to be a classic time-space tradeoff: caching
Collin Winter coll...@gmail.com added the comment:
On Fri, May 29, 2009 at 3:45 PM, Martin v. Löwis rep...@bugs.python.org wrote:
py s =
py s.join is s.join
False
Every time you read it, you get a new object. Not what I would call a
constant. If you don't see how this matters, try
def
Antoine Pitrou pit...@free.fr added the comment:
Does this optimization actually help in real-world cases?
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nosy: +pitrou
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Raymond Hettinger rhettin...@users.sourceforge.net added the comment:
Returning the same object vs new object for bound methods is a
non-guaranteed implementation detail (as long the other semantics remain
true). I think Martin's real concern is that trying to intern bound
methods would be a
Raymond Hettinger rhettin...@users.sourceforge.net added the comment:
[AP]
Does this optimization actually help in real-world cases?
Yes and no. Yes, there are real world cases like ','.join and
'{}'.format that are dramatically sped-up. No, there are probably no
real-world programs that are
Martin v. Löwis mar...@v.loewis.de added the comment:
Returning the same object vs new object for bound methods is a
non-guaranteed implementation detail (as long the other semantics remain
true). I think Martin's real concern is that trying to intern bound
methods would be a can of worms
Alex alex.gay...@gmail.com added the comment:
Optimization now works in the shell fine, and
marshal.loads(marshal.dumps(''.join)) works fine in the shell. However
when I try to run the tests the import of collections.namedtuple causes
the ValueError bad marshal data to appear, and I don't know
Raymond Hettinger rhettin...@users.sourceforge.net added the comment:
I would like to see the current patch finished and recorded here for
reference. But I agree with Martin that changing marshal is a can of
worms. The peepholer is intended to be conservative and should avoid
anything that has
Alex alex.gay...@gmail.com added the comment:
Fully functional.
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Added file: http://bugs.python.org/file14106/python_const_fold.diff
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New submission from Alex alex.gay...@gmail.com:
Basically whenever you have a LOAD_CONST opcode, follwed by a LOAD_ATTR
you can replace both with a single LOAD_CONST. This optimizes things
like , .join or {} {}.format (in my totally unscientific byte code
hackery it's about a 30% speedup on the
Alex alex.gay...@gmail.com added the comment:
Here's my work so far, it seems to work as described. Except for the
fact that pyc creation with anything containign something with this
optimization will give a valueerror on bad marshall data, from trying to
marshall the method I assume.
Alex alex.gay...@gmail.com added the comment:
Small update so I don't change whitespace all over the plcae.
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Added file: http://bugs.python.org/file14099/python_const_fold.diff
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Alex alex.gay...@gmail.com added the comment:
Switch to using memset instead of a forloop.
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Added file: http://bugs.python.org/file14100/python_const_fold.diff
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Alex alex.gay...@gmail.com added the comment:
I now *almost* have PyCFunctions marshalling, they seem to marhshall ok
but fail on unmarshalling. I think the whitespace stuff may have crept
back in, sorry :(
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Added file: http://bugs.python.org/file14101/python_const_fold.diff
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