[issue10044] small int optimization
Mark Dickinson
report at bugs.python.org
Thu Oct 7 17:53:49 CEST 2010
Mark Dickinson <dickinsm at gmail.com> added the comment:
+#define _PyLong_IS_SMALL_INT(v) \
+ (((PyLongObject *)(v)) >= _PyLong_small_ints && \
+ ((PyLongObject *)(v)) < _PyLong_SMALL_INTS_END)
+/* These macros purposedly avoid a cast to int, since it is most of time
+ useless, and sometimes detrimental (because of truncation).
+ XXX _PyLong_AS_SMALL_INT might be slower if sizeof(PyLongObject) is not
+ a power of two.
+ */
Urk! This is nasty. :(
I don't think arbitrary comparisons of pointers give well-defined results, unless those pointers both happen to point into the same array. (Might be wrong; I don't have a copy of the C standard to hand.)
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