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Re: a question about -O5
- To: Joern Rennecke <amylaar at cygnus dot co dot uk>
- Subject: Re: a question about -O5
- From: IGOR LEONIDOVICH MARKOV <imarkov at ucla dot edu>
- Date: Mon, 5 Jul 1999 18:37:21 -0700 (PDT)
- cc: law at cygnus dot com, egcs at egcs dot cygnus dot com
On Mon, 5 Jul 1999, Joern Rennecke wrote:
> > ... but Program two does not need any range checking as it
> > does not have sqrt !!!
>
> You'll probably see an improvement for this program if you add -funroll-loops
> to the options. gcc currently does not remove empty loops.
much better
Program 2 -O5
g++ 2.91 -O5 110K
g++ 2.91 -O5 -funroll_loops 10K
CC 4.2 -O5 30K
CC 5.0 -O5 0K
so, now g++ beats Sun CC4.2 in all cases,
but loses to CC5.0 in one case
Igor