Re: my crude benchmark results

[Andrew Haley <aph at redhat dot com>]

John Gabriele writes:
 > 
 > On Jul 13, 2004, at 4:57 AM, Andrew Haley wrote:
 > 
 > > John Gabriele writes:
 > 
 > Ok, using GCJ, AOT compiled, summary of my results:
 > no -O3:                   25.5 seconds
 > with -O3:                 24.2 seconds ( 5.1% improvement)
 > with -O3 and -ffast-math: 23.2 seconds ( 9.0% improvement)
 > also no-bounds-check:     22.2 seconds (12.9% improvement)
 > 
 > > ... this reminds me that we should try to get bounds check elimination
 > > into gcj before 3.5.
 > 
 > Oooh, a compile-time option to skip bounds-checking? Sweet.

No, to remove bounds checks automatically.  They're rarely needed, so
the compiler should be able usually to elimiate them.

 > Recall, I'm on a Mac here -- a PPC G3 -- so GCJ may optimize
 > differently here than on an Athlon. Also, Apple's JVM may be very
 > different from Sun's (or Blackdown's) JVM.

Your execution time is dominated by the math library, I suspect.
Given that on x86 the gcj time is almost exactly the same as the gcc
time I don't know why you have this discrepancy.  I suppose we could
have a look at the assembly code to find out.

Andrew.