[Bug regression/39914] 96% performance regression in floating point code; part of the problem started 2009/03/12-13

["lucier at math dot purdue dot edu" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #4 from lucier at math dot purdue dot edu  2009-04-27 15:11 -------
Subject: Re:  96% performance regression in floating
 point code; part of the problem started 2009/03/12-13

On Mon, 2009-04-27 at 08:16 +0000, ubizjak at gmail dot com wrote:
> 
> 
> ------- Comment #2 from ubizjak at gmail dot com  2009-04-27 08:16 -------
> (In reply to comment #0)
> 
> > (same .i file, same instructions for reproducing, same compiler options, same
> > everything)
> 
> I guess that this is direct.i compiled with -O1?
> 

Yes, the compile flags are

-Wall -W -Wno-unused -O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math
-fno-strict-aliasing -fwrapv -fomit-frame-pointer -fPIC -fno-common -mieee-fp

> It is not clear from your report, if -O1 flag is problematic, -O2 code looks
> good to me.

Yes, the -O2 code looks good to me, too.

I've used the above list of options (starting with -O1) on this code
instead of -O2 because the above list (a) has generally given faster
performance, and (b) has required much less compile time and memory to
compile the C code generated by the Gambit Scheme->C compiler.  I have
not yet seen any evidence that -O2 generates better code (overall) than
those set of options above.

Brad


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39914