languages/cpython
languages/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython synced 2024-09-21 15:31:34 +00:00
Code Issues Packages Projects Releases Wiki Activity

Merged revisions 69582-69583 via svnmerge from

Browse source 
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r69582 | antoine.pitrou | 2009-02-13 14:52:33 +0100 (ven., 13 févr. 2009) | 4 lines

  Issue #5186: Reduce hash collisions for objects with no __hash__ method by
  rotating the object pointer by 4 bits to the right.
........
  r69583 | antoine.pitrou | 2009-02-13 14:57:40 +0100 (ven., 13 févr. 2009) | 3 lines

  Fix compiler warning (gcc)
........
This commit is contained in:
Antoine Pitrou 2009-02-13 14:01:05 +00:00
parent b5de0f2f9e
commit 79eee6ba6b
2 changed files with 10 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
Misc/NEWS
View file

@ -12,6 +12,9 @@ What's New in Python 3.1 alpha 0
Core and Builtins
-----------------
- Issue #5186: Reduce hash collisions for objects with no __hash__ method by
rotating the object pointer by 4 bits to the right.
- Issue #4575: Fix Py_IS_INFINITY macro to work correctly on x87 FPUs:
it now forces its argument to double before testing for infinity.

22
Objects/object.c
View file

@ -699,23 +699,15 @@ _Py_HashDouble(double v)
long
_Py_HashPointer(void *p)
{
#if SIZEOF_LONG >= SIZEOF_VOID_P
return (long)p;
#else
/* convert to a Python long and hash that */
PyObject* longobj;
long x;
if ((longobj = PyLong_FromVoidPtr(p)) == NULL) {
x = -1;
goto finally;
}
x = PyObject_Hash(longobj);
finally:
Py_XDECREF(longobj);
size_t y = (size_t)p;
/* bottom 3 or 4 bits are likely to be 0; rotate y by 4 to avoid
excessive hash collisions for dicts and sets */
y = (y >> 4) | (y << (8 * SIZEOF_VOID_P - 4));
x = (long)y;
if (x == -1)
x = -2;
return x;
#endif
}
long