[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2022-01-18 Thread Raymond Hettinger 


Raymond Hettinger  added the comment:


New changeset 243c31667cc15a9a338330ad9b2a29b1cd1c76ec by Raymond Hettinger in 
branch 'main':
bpo-42161: Hoist the _PyLong_GetOne() call out of the inner loop. (GH-30656)
https://github.com/python/cpython/commit/243c31667cc15a9a338330ad9b2a29b1cd1c76ec


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2022-01-17 Thread Raymond Hettinger 


Change by Raymond Hettinger :


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pull_requests: +28857
pull_request: https://github.com/python/cpython/pull/30656

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-05-26 Thread STINNER Victor 


STINNER Victor  added the comment:


New changeset 4115996342278de7c2a1b59ac348322e7a4e9072 by Miss Islington (bot) 
in branch '3.10':
bpo-42161: mathmodule.c: move _PyLong_GetOne() loop invariant (GH-26391) 
(GH-26393)
https://github.com/python/cpython/commit/4115996342278de7c2a1b59ac348322e7a4e9072


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-05-26 Thread STINNER Victor 


STINNER Victor  added the comment:

Raymond: "Can you fix all the other cases where this is used in inner-loop; 
otherwise, it is undoing everyone else's optimizations and fast paths."

Done, thanks for the report.

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status: open -> closed

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-05-26 Thread miss-islington 


Change by miss-islington :


--
nosy: +miss-islington
nosy_count: 6.0 -> 7.0
pull_requests: +24986
pull_request: https://github.com/python/cpython/pull/26393

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-05-26 Thread STINNER Victor 


STINNER Victor  added the comment:


New changeset 3e7ee02327db13e4337374597cdc4458ecb9e3ad by Victor Stinner in 
branch 'main':
bpo-42161: mathmodule.c: move _PyLong_GetOne() loop invariant (GH-26391)
https://github.com/python/cpython/commit/3e7ee02327db13e4337374597cdc4458ecb9e3ad


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-05-26 Thread STINNER Victor 


Change by STINNER Victor :


--
pull_requests: +24984
stage: resolved -> patch review
pull_request: https://github.com/python/cpython/pull/26391

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-03-18 Thread Raymond Hettinger 


Raymond Hettinger  added the comment:

I don't have a PR in-hand.  I just ran across this when trying to explain 3.9 
vs 3.10 timings and M-1 vs Intel timings.   Ideally, all of these PRs should be 
reverted.  Short of that, each change needs to be reviewed to see if it created 
extra work inside a loop.  There are 35 calls to PyLong_GetOne and 3 for 
PyLong_GetZero.  Each of those should be checked.

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-03-18 Thread Mark Dickinson 


Change by Mark Dickinson :


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nosy: +mark.dickinson

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-03-18 Thread STINNER Victor 


STINNER Victor  added the comment:

Since it seems like you have already a ready patch to optimize the code, so go 
ahead and merge it.

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2021-03-17 Thread Raymond Hettinger 


Raymond Hettinger  added the comment:

> Thanks Raymond, I fixed the code.

Can you fix all the other cases where this is used in inner-loop; otherwise, it 
is undoing everyone else's optimizations and fast paths.

Also, it seems the that primary motivation for this is support subinterpreters. 
 That PEP hasn't been approved, so we should not be making code worse until we 
know there is going to some offsetting benefit.

For example, the inner-loop code in math_lcm() used to have "res == 
_PyLong_Zero" which was fast a register-to-register comparison (1 cycle at 
worst and typically 0 cycles with branch prediction).  Also there used to be 
zero memory accesses.   The new code has five sequentially dependent operations 
and four memory accesses (not what we want in an inner-loop):

movq__PyRuntime@GOTPCREL(%rip), %rax
movq616(%rax), %rax
movq16(%rax), %rax
cmpq%r12, 3560(%rax)
jne L326

Ideally, the whole PR should be reverted until the subinterpreter PEP is 
approved.  If not, then at least the changes should be made more carefully, 
hoisting the new call out of the hot loop:

+   zero = _PyLong_GetZero();
for (i = 1; i < nargs; i++) {
x = PyNumber_Index(args[i]);
if (x == NULL) {
Py_DECREF(res);
return NULL;
}
-   if (res == _PyLong_GetZero()) {
+   if (res == zero) {
/* Fast path: just check arguments.
   It is okay to use identity comparison here. */
Py_DECREF(x);
continue;
}
Py_SETREF(res, long_lcm(res, x));
Py_DECREF(x);
if (res == NULL) {
return NULL;
}
}
return res;

--
nosy: +pablogsal, serhiy.storchaka
status: closed -> open

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread STINNER Victor 


STINNER Victor  added the comment:

Thanks Raymond, I fixed the code.

I close the issue, I removed _PyLong_Zero and _PyLong_One variables.

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stage: patch review -> resolved
status: open -> closed

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread STINNER Victor 


STINNER Victor  added the comment:


New changeset 35b95aaf21534e4a8e3370dfd6f7482265316c9e by Victor Stinner in 
branch 'master':
bpo-42161: Micro-optimize _collections._count_elements() (GH-23008)
https://github.com/python/cpython/commit/35b95aaf21534e4a8e3370dfd6f7482265316c9e


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread STINNER Victor 


STINNER Victor  added the comment:


New changeset c310185c081110741fae914c06c7aaf673ad3d0d by Victor Stinner in 
branch 'master':
bpo-42161: Remove private _PyLong_Zero and _PyLong_One (GH-23003)
https://github.com/python/cpython/commit/c310185c081110741fae914c06c7aaf673ad3d0d


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread STINNER Victor 


STINNER Victor  added the comment:

> Why did you put _PyLong_GetOne() inside the loop for the fast path and 
> outside the loop for the slow path?

Oh, I didn't notice that the first part was also a loop. I wrote PR 23008 to 
move the call out of the loop.

I tried to avoid calling the function if it's possible that the variable it not 
used. But here, it's always used, so it's relevant to move the loop invariant 
out of the loop ;-)

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread STINNER Victor 


Change by STINNER Victor :


--
pull_requests: +21924
pull_request: https://github.com/python/cpython/pull/23008

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread Raymond Hettinger 


Raymond Hettinger  added the comment:

Why did you put _PyLong_GetOne() inside the loop for the fast path and outside 
the loop for the slow path?


==
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 8990071f51..0e6c64d1a6 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -2278,6 +2278,8 @@ _collections__count_elements_impl(PyObject *module, 
PyObject *mapping,
 PyObject *dict_get;
 PyObject *mapping_setitem;
 PyObject *dict_setitem;
+PyObject *zero = _PyLong_GetZero();  // borrowed reference
+PyObject *one = _PyLong_GetOne();// borrowed reference

 it = PyObject_GetIter(iterable);
 if (it == NULL)
@@ -2324,10 +2326,10 @@ _collections__count_elements_impl(PyObject *module, 
PyObject *mapping,
 if (oldval == NULL) {
 if (PyErr_Occurred())
 goto done;
-if (_PyDict_SetItem_KnownHash(mapping, key, _PyLong_GetOne(), 
hash) < 0)
+if (_PyDict_SetItem_KnownHash(mapping, key, one, hash) < 0)
 goto done;
 } else {
-newval = PyNumber_Add(oldval, _PyLong_GetOne());
+newval = PyNumber_Add(oldval, one);
 if (newval == NULL)
 goto done;
 if (_PyDict_SetItem_KnownHash(mapping, key, newval, hash) < 0)
@@ -2341,8 +2343,6 @@ _collections__count_elements_impl(PyObject *module, 
PyObject *mapping,
 if (bound_get == NULL)
 goto done;

-PyObject *zero = _PyLong_GetZero();  // borrowed reference
-PyObject *one = _PyLong_GetOne();  // borrowed reference
 while (1) {
 key = PyIter_Next(it);
 if (key == NULL)

--
nosy: +rhettinger

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread STINNER Victor 


Change by STINNER Victor :


--
pull_requests: +21918
pull_request: https://github.com/python/cpython/pull/23003

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-27 Thread STINNER Victor 


STINNER Victor  added the comment:


New changeset 37834136d0afe51d274bfc79d8705514cbe73727 by Victor Stinner in 
branch 'master':
bpo-42161: Modules/ uses _PyLong_GetZero() and _PyLong_GetOne() (GH-22998)
https://github.com/python/cpython/commit/37834136d0afe51d274bfc79d8705514cbe73727


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-26 Thread STINNER Victor 


Change by STINNER Victor :


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pull_requests: +21913
pull_request: https://github.com/python/cpython/pull/22998

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-26 Thread STINNER Victor 


STINNER Victor  added the comment:


New changeset c9bc290dd6e3994a4ead2a224178bcba86f0c0e4 by Victor Stinner in 
branch 'master':
bpo-42161: Use _PyLong_GetZero() and _PyLong_GetOne() (GH-22995)
https://github.com/python/cpython/commit/c9bc290dd6e3994a4ead2a224178bcba86f0c0e4


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-26 Thread Dong-hee Na 


Change by Dong-hee Na :


--
nosy: +corona10

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-26 Thread STINNER Victor 


Change by STINNER Victor :


--
pull_requests: +21909
pull_request: https://github.com/python/cpython/pull/22995

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-26 Thread STINNER Victor 


STINNER Victor  added the comment:


New changeset 8e3b9f92835654943bb59d9658bb52e1b0f40a22 by Victor Stinner in 
branch 'master':
bpo-42161: Add _PyLong_GetZero() and _PyLong_GetOne() (GH-22993)
https://github.com/python/cpython/commit/8e3b9f92835654943bb59d9658bb52e1b0f40a22


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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-26 Thread STINNER Victor 


Change by STINNER Victor :


--
keywords: +patch
pull_requests: +21907
stage:  -> patch review
pull_request: https://github.com/python/cpython/pull/22993

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[issue42161] Remove private _PyLong_Zero and _PyLong_One variables

2020-10-26 Thread STINNER Victor 


New submission from STINNER Victor :

In bpo-38858, I made the small integer singletons per interpreter: commit 
630c8df5cf126594f8c1c4579c1888ca80a29d59. _PyLong_Zero and _PyLong_One 
variables are still shared by all interpreters, whereas subinterpreters must 
not share Python objects: see bpo-40533.

I propose to add new _PyLong_GetZero() and _PyLong_GetOne() functions to 
replace _PyLong_Zero and _PyLong_One variables. These functions will retrieve 
the singletons from tstate->interp->small_ints.

--
components: Interpreter Core
messages: 379691
nosy: vstinner
priority: normal
severity: normal
status: open
title: Remove private _PyLong_Zero and _PyLong_One variables
versions: Python 3.10

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