according to the manpage, -fschedule-insns is enabled at the optimization levels -O2, -O3 and -Os. according to g++ -c -Q --help=optimizers, this is not the case, though.
-- Summary: man page: -fschedule-insns documentation Product: gcc Version: 4.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: other AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: tim at klingt dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38768