-floop-optimize2

[Richard Guenther]

On 6/21/05, Scott Robert Ladd <scott.ladd@coyotegulch.com> wrote:
> I've noticed that -floop-optimize2 tends to be a pessimism on many
> algorithms.
> 
> I'm hesitant to file this as a "bug", given that -floop-optimize2 is a
> "new" replacement for the older loop optimizer.
> 
> Is -floop-optimize2 still in development, and not ready yet -- or are
> the problems I'm seeing something that should be analyzed and reported
> as a bug?

The pessimization is that the old loop optimizer is turned off, if you
specify -floop-optimize2.  The new loop optimizer is also (additionally)
enabled if you specify either of -fmove_loop_invariants
-funswitch_loops -fpeel_loops -funroll_loops or -fbranch_on_count_reg.

As the old loop optimizer is (hopefully) going away sooner or later
small testcases are surely welcome that identify weak spots of the new
loop optimizer.

Richard.