Richard Kenner wrote:
Note the interesting places in VRP where it assumes undefined signed
overflow is in compare_values -- we use the undefinedness to fold
comparisons.
Unfortunately, comparisons are the trickiest case because you have to
be careful to avoid deleting a comparison that exists to see if overflow
occured: this is perhaps the most common place where wrapping is assumed.
Note incidentally regarding Fortran that testing for overflow is
at least as difficult in Fortran as in C (unless new stuff has been
added to Fortran since my Fortran days, which is certainly possible).
