Speed Impact experiment on GCJ

Thu Feb 16 15:17:00 GMT 2006

Rui Wang writes:
 > >
 > >REMARK: Obviously, the JIT discovers that the loop is not 
 > >really a loop sometime during the first iterations and decides 
 > >to optimize pretty hard...
 > 
 > -sh-2.05b$ cat jresult.d 
 > 200.0 23 
 > 300.0 9 
 > 400.0 0 
 > 500.0 1 
 > 600.0 0 
 > 700.0 1 
 > 1000.0 1 
 > 2000.0 2 
 > 5000.0 4 
 > 10000.0 6 
 > 20000.0 12 
 > 30000.0 13 
 > 
 > >gcj at -O3:
 > >
 > >[thhal@localhost gcjtest]$ time ./client task.test servers.d result.d
 > >
 > >real 0m1.469s
 > >user 0m1.265s
 > >sys 0m0.202s
 > >
 > >200.0 184
 > >300.0 276
 > >400.0 346
 > >500.0 442
 > -sh-2.05b$ cat result.d
 > 200.0 1 
 > 300.0 0 
 > 400.0 0 
 > 500.0 0 
 > 600.0 0 
 > 700.0 0 
 > 1000.0 0 
 > 2000.0 0 
 > 5000.0 1 
 > 10000.0 1 
 > 20000.0 1 
 > 30000.0 3 
 > 
 > There are two possible reasons: 
 > 1. different gcj version ( I am using 4.2.0, and yours is 4.0.0),
 > but I doubt this is the problem.
It is.
 > 2. you didn't put -O3 while compiling the bytecode to object file. If
 > you try it
 > With -O3, it will actually make a huge difference. But I don't know why
 > through, would somebody 
 > On this maillist mind to answer this question?
gcj -v --help
Andrew.