In PR42108 a division is found to be non-trapping by VRP but neither PRE nor LIM can make use of that information (well, because VRP doesn't mark the divisions in any meaningful way).
-- Summary: VRP should mark non-trapping integer divisions Product: gcc Version: 4.5.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: rguenth at gcc dot gnu dot org OtherBugsDependingO 42108 nThis: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42436