Bugs item #1545668, was opened at 2006-08-24 03:14 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1545668&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Macintosh Group: Python 2.4 Status: Open Resolution: None Priority: 5 Submitted By: Jack Howarth (jwhowarth) Assigned to: Jack Jansen (jackjansen) Summary: gcc trunk (4.2) exposes a signed integer overflows Initial Comment: While building python 2.4.3 with the current gcc trunk (soon to be 4.2), I uncovered a signed integer overflows bug in Python with the help of one of the gcc developers. The bug I observed is documented in this gcc mailing list message... http://gcc.gnu.org/ml/gcc/2006-08/msg00436.html The gcc developer comments about its origin are in the messages... http://gcc.gnu.org/ml/gcc/2006-08/msg00434.html http://gcc.gnu.org/ml/gcc/2006-08/msg00442.html which in short says... It *is* a bug in python, here is the proof: https://codespeak.net/viewvc/vendor/cpython/Python-r243/dist/src/ Objects/intobject.c?revision=25647&view=markup Function * i_divmod*(*register* *long* x, *register* *long* y, the following lines: / /* (-sys.maxint-1)/-1 is the only overflow case. *// *if* (y == -1 && x < 0 && x == -x) *return* DIVMOD_OVERFLOW; If overflow is barred then x==-x may happen only when x==0. This conflicts with x<0, which means that the compiler may assume that x<0 && x==-x always yields false. This may allow the compiler to eliminate the whole if statement. Hence, clearly python is at fault. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1545668&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
