Loop unrolling-related SPEC regressions?

[Andreas Jaeger]

Dale Johannesen <dalej@apple.com> writes:

> Intelligent use of profiling info from the first pass is
> important.  You'll see the published numbers do this.
> Last time I looked gcc used this only for branch
> straightening; it can also be used effectively to
> drive inlining and register allocation.

AFAIK the infrastructure is there, it only needs to be used for
inlining - and also in the new register allocator.  Michal, is this
possible?


> crafty is heavily dependent on efficiency of "long long".
> It's a chess program, full of 64-bit bitmasks.
>
> eon is the only one in C++.  If there are any problems
> in exception handling they will show up here.  The program
> does not actually throw any exceptions, so turning off
> the handling for peak may help (SPEC won't let you turn
> it off for base).  Good inlining decisions are also important.

The inline change brought in August by Kurt Garloff brought a real
performance improvement, check my graphs at http://www.suse.de/~aj/SPEC

> the two most heavily executed functions in perl are big;
> IME register allocation & scheduling don't always work
> well for big functions.  They also both call setjmp; if
> this disables any substantial amount of optimization it
> will hurt.
>
> vortex accesses a huge amount of virtual memory.  Good
> malloc/free performance is critical.


Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj