We cannot vectorize the following loop because the "number of iterations cannot be computed".
int f(int *s, int *e) { while ( s < e ) *s++ = 0; } This acutally shows up in SPEC (gap). -- Summary: not vectorizing obvious loop Product: gcc Version: 4.0.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P2 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: pinskia at gcc dot gnu dot org CC: gcc-bugs at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18813