[Bug driver/56244] New: -O3 should imply -funroll-loops

[Joost.VandeVondele at mat dot ethz.ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56244

             Bug #: 56244
           Summary: -O3 should imply -funroll-loops
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: driver
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: Joost.VandeVondele@mat.ethz.ch


As suggested by Richard, -O3 should imply -funroll-loops

http://gcc.gnu.org/ml/gcc/2013-02/msg00073.html

I think this makes a lot of sense. For our simulation codes, we essentially add
it 'by default' yielding small but measurable speedups (1%?).

Having it on by default (like vectorization), will likely improve the
heuristics, and the interaction with e.g. vectorization will improve.