The documentation for -ftree-vectorizer-verbose doesn't give the slightest hints on useful values for n:
"-ftree-vectorizer-verbose=n This option controls the amount of debugging output the vectorizer prints. This information is written to standard error, unless -fdump-tree-all or -fdump-tree-vect is specified, in which case it is output to the usual dump listing file, .vect." -- Summary: -ftree-vectorizer-verbose=n documentation is terse Product: gcc Version: 4.2.0 Status: UNCONFIRMED Keywords: documentation Severity: normal Priority: P3 Component: other AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: rguenth at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26419