Eugene Toder added the comment:
@cache does not address the problem or any of the concerns brought up in the
thread. Thread-safe @once is a nice idea, but more work of course.
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Eugene Toder added the comment:
Ammar, thank you for the link.
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Eugene Toder added the comment:
As you can see in my original post, the difference between @cache (aka
@lru_cache(None)) and just @lru_cache() is negligible in this case. The
optimization in this PR makes a much bigger difference. At the expense of some
lines of code, that's true.
Also
New submission from Eugene Toder :
It's convenient to use @lru_cache on functions with no arguments to delay doing
some work until the first time it is needed. Since @lru_cache is implemented in
C, it is already faster than manually caching in a closure variable. However,
it can be made even
Change by Eugene Toder :
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New submission from Eugene Toder :
If a module has a loader, linecache calls its get_source() passing __name__ as
the argument. This works most of the time, except that the __main__ module has
it set to "__main__", which is commonly not the real name of the module.
Luckily, w
Eugene Toder added the comment:
Yes, doing optimizations on AST in CPython is unlikely to give any sizable
speed improvements in real world programs. Python as a language is not suited
for static optimization, and even if you manage to inline a function, there's
still CPython's interpreted
Eugene Toder added the comment:
> We have already Constant and NameConstant. So it seems there are no need for
> None, Bool, TupleConst, SetConst nodes.
Yes, Constant is Victor's version of Lit.
> I think converting Num, Str, Bytes, Ellipsis into Constant in folding stage
> is
Eugene Toder added the comment:
namedtuple._replace() actually doesn't call subclass' __new__. It calls
tuple.__new__ directly, so it has the same problem as datetime classes.
Parameter and Signature are new in 3.3. I'm not sure if they're expected to be
used as base classes.
@r.david.murray
Eugene Toder added the comment:
This seems like it can lead to even more subtle bugs when replace() is not
overriden. Currently, any extra state in the subclass is left uninitialized,
which usually leads to obvious breakage and is relatively easy to trace back to
replace(). (I've done
Eugene Toder added the comment:
Yes, this is similar to my second approach. (You need to copy via __reduce__,
because __copy__ my have been overriden to return self.)
The general problem with it, is that if a subclass is designed to be immutable
(probably a common case here), it may
Eugene Toder added the comment:
Properly supporting subclasses in replace() is hard, at least without some
cooperation from subclasses. For a proper replace()
x.replace(a=newval).b == x.b
should hold for every b not dependent on a, including ones added by subclasses.
That is, it should
Eugene Toder added the comment:
Serhiy: Nice! Yes, _PyCode_ConstantKey solved the problem.
But #16619 went in the opposite direction of this patch, and introduced a new
type of literal node instead of unifying the existing ones. Kind of a shame,
since *this* patch, I believe, both fixes
Eugene Toder added the comment:
Fairly sure it's 5 years old.
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Eugene Toder added the comment:
They sure do. Check the example in my comment, or if you prefer the source
code, it's pretty clear as well:
https://hg.python.org/cpython/file/fff0c783d3db/Modules/_datetimemodule.c#l2770
--
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Eugene Toder added the comment:
There's a similar issue with replace() methods on date/time/datetime classes.
They create instances of derived types without calling derived
__new__/__init__, thus potentially leaving those uninitialized.
>>> from datetime import date
>>
Changes by Eugene Toder <elto...@gmail.com>:
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Eugene Toder added the comment:
Guido: IIUC the general intention is to support @property and __getattr__ style
hooks on the module level. Assigning to sys.modules[name] from the module
itself is a bit too late -- there's already a global dict for this module, and
no way to create a module
Eugene Toder added the comment:
Nathaniel, what if we allow creating module objects from an existing dict
instead of always creating a new one. Does this solve your namespace diversion
problem?
FWIW, when I discovered this change I was quite surprised this came through
without a PEP. I agree
Eugene Toder added the comment:
Thank you!
Benjamin, Nathaniel, any opinion if we should restrict reassigning __class__
for types like tuple, int and str, where some/many instances are cached?
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Eugene Toder added the comment:
Agreed. There's a small problem with that, as far as I know. Nothing on type
declares that it is immutable.
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Added file: http://bugs.python.org/file38624/class_gc2.diff
___
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New submission from Eugene Toder:
As far as I can tell, if a new class does not add any new fields, and its base
class doesn't use GC, there's no reason to enable GC for the new class.
This is useful for creating lightweight wrappers around classes implemented in
C.
--
files
Eugene Toder added the comment:
Agreed, but this is not new. This works without my change:
class Tuple(tuple):
... __slots__ = ()
... def __repr__(self): return 'Imma tuple!'
...
().__class__ = Tuple
()
Imma tuple
Eugene Toder added the comment:
Actually, this is rather new -- new in 3.5. The check was relaxed in #22986:
https://hg.python.org/cpython/rev/c0d25de5919e
Previously only heap types allowed re-assigning __class__.
--
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Eugene Toder added the comment:
If you add co_firstlineno into code_hash you can say something like
/* The rest isn't used in hash and comparisons, except
co_name and co_firstlineno, which are preserved for
tracebacks and debuggers. */
(Otherwise you'd need to explain why co_firstlineno
Eugene Toder added the comment:
My comment will make more sense if you follow the links that I provided.
Brett's check-in (http://hg.python.org/cpython-fullhistory/rev/8127a55a57cb)
says that it fixes bug #1190011
(http://www.mail-archive.com/python-bugs-list@python.org/msg02440.html
Eugene Toder added the comment:
To recap, the issue is that pickle doesn't handle recursion via reduce
arguments (i.e. arguments to the constructor function as returned in 2nd
element of the tuple from __reduce__). This leads to 2 kind of effects:
class C:
def __init__(self, x=None
Changes by Eugene Toder elto...@gmail.com:
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Eugene Toder added the comment:
Thank you, Antoine.
This change has one effect that's worth highlighting in NEWS at least -- the
PyWeakref_GET_OBJECT() macro now evaluates its argument twice. This can break
existing code where the argument has side-effects, e.g. o =
PyWeakref_GET_OBJECT(p
Eugene Toder added the comment:
People should simply avoid doing this kind of thing, as it's knowingly
fragile, and trivial to avoid anyway.
Is this documented in the C API guide, or somewhere else?
In any case, notifying people so they can quickly check their code seems much
nicer than
Eugene Toder added the comment:
Agreed. That's what I've put in my code as a work around.
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New submission from Eugene Toder:
An interaction between weakrefs and trashcan can cause weakref to return the
object it's pointing to after object's refcount is already 0. Given that the
object is usually increfed and decrefed, this leads to double dealloc and
crashing or hanging.
Tested
Eugene Toder added the comment:
Method calls on literals are always fair game, though (e.g. you could
optimise a b c.split())
What about optimizations that do not change behavior, except for different
error messages? E.g. we can change
y = [1,2][x]
to
y = (1,2)[x]
where the tuple is constant
Eugene Toder added the comment:
If I'm not missing something, changing
x in [1,2]
to
x in (1,2)
and
x in {1,2}
to
x in frozenset([1,2])
does not change any error messages.
Agreed that without dynamic compilation we can pretty much only track literals
(including functions and lambdas) assigned
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Eugene Toder elto...@gmail.com added the comment:
They are, when there's a most specific metaclass -- the one which is a subclass
of all others (described here
http://www.python.org/download/releases/2.2.3/descrintro/#metaclasses,
implemented here
http://hg.python.org/cpython/file
Eugene Toder elto...@gmail.com added the comment:
So how about this correction?
--
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Added file: http://bugs.python.org/file22375/setstate.diff
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http
Eugene Toder elto...@gmail.com added the comment:
Anyone has any thoughts on this?
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http://bugs.python.org/issue5996
Eugene Toder elto...@gmail.com added the comment:
I found a problem in constant de-duplication, already performed by compiler,
that needs to be fixed before this change can be merged.
Compiler tries to eliminate duplicate constants by putting them into a dict.
However, duplicate in this case
New submission from Eugene Toder elto...@gmail.com:
Pickle documentation [1] says:
Note: If __getstate__() returns a false value, the __setstate__() method
will not be called upon unpickling.
However, this isn't quite true. This depends on the version of pickle protocol.
A small example
Changes by Eugene Toder elto...@gmail.com:
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Eugene Toder elto...@gmail.com added the comment:
Nick, if there's an interest in reviewing the patch I can update the it. I
doubt it needs a lot of changes, given that visitor is auto-generated.
Raymond, the patch contains a rewrite of low-level optimizations to work before
byte code
Eugene Toder elto...@gmail.com added the comment:
It appears that
* co_name was added to hash and cmp in this check-in by Guido:
http://hg.python.org/cpython-fullhistory/diff/525b2358721e/Python/compile.c
I think the reason was to preserve function name when defining multiple
functions
Eugene Toder elto...@gmail.com added the comment:
Btw, disabling dedup for codes won't be the first exception -- we already avoid
coalescing -0.0 with 0.0 for float and complex, even though they compare equal.
--
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Eugene Toder elto...@gmail.com added the comment:
I would propose changing implementation to match the comment. At a minimum,
remove co_firstlineno comparison. As the last resort, at least change the
comment.
--
___
Python tracker rep
New submission from Eugene Toder elto...@gmail.com:
A comment in the definition of PyCodeObject in Include/code.h says:
/* The rest doesn't count for hash or comparisons */
which, I think, makes a lot of sense. The implementation doesn't follow this
comment, though. code_hash actually
Eugene Toder elto...@gmail.com added the comment:
So in the near term, dis-based tests should continue to copy/paste sys.stdout
redirection code?
--
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New submission from Eugene Toder elto...@gmail.com:
As discussed in Issue11549 a couple of tests need to inspect disassembly of
some code. Currently they have to override sys.stdout, run dis and restore
stdout back. It would be much nicer if dis module provided functions that
return
Changes by Eugene Toder elto...@gmail.com:
Removed file: http://bugs.python.org/file21598/dis.diff
___
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Changes by Eugene Toder elto...@gmail.com:
Added file: http://bugs.python.org/file21599/dis.patch
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Eugene Toder elto...@gmail.com added the comment:
Agreed, but that would require rewriting of all tests in test_peepholer.
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Eugene Toder elto...@gmail.com added the comment:
This patch fixes the problem by moving the check from object_new to
PyType_GenericAlloc. The check is very cheap, so this should not be an issue.
--
keywords: +patch
nosy: +eltoder
Added file: http://bugs.python.org/file21600/abc.patch
Eugene Toder elto...@gmail.com added the comment:
If we have to preserve backward compatibility of Python AST API, we can do this
relatively easily (at the expense of some code complexity):
* Add 'version' argument to compile() and ast.parse() with default value of 1
(old AST). Value 2
Eugene Toder elto...@gmail.com added the comment:
Thanks.
string concatenation will now work, and errors like 'hello' - 'world'
should give a more informative TypeError
Yes, 'x'*5 works too.
Bikeshed: We use Attribute rather than Attr for that node type,
perhaps the full Literal name would
Eugene Toder elto...@gmail.com added the comment:
and with __future__ it should work on 2.5 as well.
Actually, seems that at least str.format is not in 2.5 as well. Still the
question is should I make it run on 2.5 or 2.4 or is 2.6 OK (then __future__
can be removed
Eugene Toder elto...@gmail.com added the comment:
I don't think it can:
That already doesn't work in dict and set (eq not consistent with hash), I
don't think it's a big problem if that stops working in some other cases.
Anyway, I said theoretically -- maybe after some conservative type
Eugene Toder elto...@gmail.com added the comment:
Also, to avoid any confusion -- currently my patch only runs AST optimizations
before code generation, so compile() with ast.PyCF_ONLY_AST returns
non-optimized AST.
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Eugene Toder elto...@gmail.com added the comment:
Is anyone looking or planing to look at the patch?
--
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Eugene Toder elto...@gmail.com added the comment:
AFAICT my patch has everything that #1346238 has, except BoolOps, which can be
easily added (there's a TODO). I don't want to add any new code, though, until
the current patch will get reviewed -- adding code will only make reviewing
harder
Eugene Toder elto...@gmail.com added the comment:
Any comments on the code so far or suggestions on how we should move forward?
--
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Eugene Toder elto...@gmail.com added the comment:
I've updated patches on Rietveld with some small changes. This includes better
code generation for boolops used outside of conditions and cleaned up
optimize_jumps(). This is probably the last change before I get some feedback.
Also, I forgot
Eugene Toder elto...@gmail.com added the comment:
Just for fun I've run pystones. W/o my changes it averages to about 70k, with
my changes to about 72.5k.
--
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Eugene Toder elto...@gmail.com added the comment:
Is anyone reviewing my patch? It's just 1 line long. Should it be moved to
another issue? Though, technically, it's needed to address the regression in
question: Python 3.1 folds -0, the current code still does
Eugene Toder elto...@gmail.com added the comment:
Because I don't know how to make them. Any pointers?
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Eugene Toder elto...@gmail.com added the comment:
Thanks. Review link: http://codereview.appspot.com/4281051
--
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Eugene Toder elto...@gmail.com added the comment:
I see. Should I attach diffs vs. some revision from hg.python.org?
--
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New submission from Eugene Toder elto...@gmail.com:
Since the time 'x in set' optimization was added to peephole it has the
following bug with set unpacking:
def foo(x,y):
a,b = {x,y}
return a,b
dis(foo)
2 0 LOAD_FAST0 (x)
3
New submission from Eugene Toder elto...@gmail.com:
As pointed out by Raymond, constant folding should be done on AST rather than
on generated bytecode. Here's a patch to do that. It's rather long, so overview
first.
The patch replaces existing peephole pass with a folding pass on AST
Changes by Eugene Toder elto...@gmail.com:
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Added file: http://bugs.python.org/file21198/0_ast.patch
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Added file: http://bugs.python.org/file21199/0_fold.patch
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Added file: http://bugs.python.org/file21200/0_compile.patch
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Eugene Toder elto...@gmail.com added the comment:
Antoine, sure, I'll fix it with any other suggested changes if patches will be
accepted.
--
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Eugene Toder elto...@gmail.com added the comment:
Mark, looks better now?
--
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Changes by Eugene Toder elto...@gmail.com:
Removed file: http://bugs.python.org/file21082/fold-0.patch
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Eugene Toder elto...@gmail.com added the comment:
(forgot parens around 0)
--
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Eugene Toder elto...@gmail.com added the comment:
- why the #ifndef NDEBUG path?
These entries in the table should not be used, but if something slips through
and uses one of them, it's much easier to tell if we remap to invalid value. As
this is an internal check, I didn't want it in release
Eugene Toder elto...@gmail.com added the comment:
assert() doesn't quite work here. I need to check that this entry in the table
is not used in the next loop. I'd need to put assert in that loop, but by that
time I have no easy way to tell which entries are bad, unless I mark them
Eugene Toder elto...@gmail.com added the comment:
_PyCode_AddObj() should be added to Include/code.h
Should it be declared as PyAPI_FUNC too? This will make it unnecessarily
exported (when patch in Issue11410 is merged), so I wanted to avoid that.
btw, that you for reviewing the patch
Eugene Toder elto...@gmail.com added the comment:
Right now, the pattern is tokenize - parse - AST - genbytecode -
peephole optimization (which disassembles the bytecode, analyzed it
and rewrites it) - final bytecode. The correct pattern is tokenize
- parse - AST - optimize - genbytecode
New submission from Eugene Toder elto...@gmail.com:
If statement without else part generates unnecessary JUMP_FORWARD insn with
jumps right to the next insn:
def foo(x):
if x: x = 1
dis(foo)
2 0 LOAD_FAST0 (x)
3 POP_JUMP_IF_FALSE 15
Eugene Toder elto...@gmail.com added the comment:
Test case (needed some refactoring to avoid duplication).
--
Added file: http://bugs.python.org/file21092/if_no_else_test.patch
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Eugene Toder elto...@gmail.com added the comment:
Thomas, can you clarify, does loading interns all constants in co_consts, or do
you mean that they are mostly small numbers and the like?
Without interning I think that in-memory size difference is even bigger than
on-disk, as you get one
Eugene Toder elto...@gmail.com added the comment:
Yes, my patch doesn't fix the regression, only a special case of -0.
--
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http://bugs.python.org/issue11244
Eugene Toder elto...@gmail.com added the comment:
Alexander, my patch does 2 optimizations: doesn't insert a new constant if one
already exist and removes unused constants after peephole is done. You patch
seems to do only the latter. It's very similar, from a quick look at your patch:
- My
Eugene Toder elto...@gmail.com added the comment:
Raymond, you can be assured that I'm not developing this patch, unless I'm told
it has chances to be accepted. I don't like to waste my time. On a related
note, your review of my other patches is appreciated
Eugene Toder elto...@gmail.com added the comment:
As discussed on the list, peephole refuses to fold -0. The reasons for this are
unclear. Folding was disabled with this commit:
http://hg.python.org/cpython/diff/660419bdb4ae/Python/compile.c
Here's a trivial patch to enable the folding again
New submission from Eugene Toder elto...@gmail.com:
Peephole optimizer performs constant folding, however
1) When it replaces operation with LOAD_CONST it always adds a new constant to
co_consts, even if constant with the same value is already there. It also can
add the same constant multiple
Changes by Eugene Toder elto...@gmail.com:
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Added file: http://bugs.python.org/file21074/dedup_const_plana.patch
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Eugene Toder elto...@gmail.com added the comment:
(either plana or planb should be applied)
--
Added file: http://bugs.python.org/file21075/dedup_const_planb.patch
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Changes by Eugene Toder elto...@gmail.com:
Added file: http://bugs.python.org/file21076/unused_consts.patch
___
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Eugene Toder elto...@gmail.com added the comment:
(test case)
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Added file: http://bugs.python.org/file21077/consts_test.patch
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Eugene Toder elto...@gmail.com added the comment:
I think the changes are fairly trivial. dedup_const_planb.patch is about 10
lines of new code with all the rest being trivial plubming. unused_consts.patch
may look big, but only because I factored out fix ups into a separate function
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