> I'd be happy to re-run the tests sometime.

Yes, please!  Alternatively, if there are easy instructions for us to re-run these tests, that would be valuable, too.  Do I understand correctly that you have a publicly available extension to LLVM for this?

> Basically it'll act as a more powerful -ftrapv, and the error message will be much better than "aborted".

Indeed---there were a number of places where tracking down the exact cause of the error using a combination of -ftrapv and gdb was painful. :-)

I'm aware of two current issues: one in Python/formatter_unicode.c, and one in Modules/timemodule.c.  I'll try to fix these shortly.