[Bug tree-optimization/42436] VRP should mark non-trapping integer divisions

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42436

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think this was trying to cover things like

  if (d != 0)
    tem = a / d;

where the non-zero range of d on the division cannot be put in global ranges
for its SSA name since that would be incorrect for uses not guarded by the
condition.  So it would ask for a new flag on GIMPLE statements to mark the
division not trapping (like we have TREE_THIS_NOTRAP).  Transforms like
PRE or LIM that do code motion of course have to be careful to not move
the stmt outside of the condition that made it not trapping - something which
would be as hard to guarantee as computing the non-trappingness in the first
place.

So yes, the case that made me file this bug is fixed with global ranges.

Let's close this bug since it's quite unspecific.