Message-ID: <36DDD2C1.421DD4AF@t-online.de>
Date: Thu, 04 Mar 1999 01:24:33 +0100
Organization: LISA GmbH
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To: pgcc AT delorie DOT com
Subject: Re: gcc-2.7.0 creates faster code than pgcc-1.1.1
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From: hpj DOT lisa AT t-online DOT de (Hans-Peter Jansen)
Reply-To: pgcc AT delorie DOT com

Marc Lehmann wrote:
> 
> On Tue, Mar 02, 1999 at 05:13:25PM -0600, Jeffrey Hundstad wrote:
> > On  2 Mar, Dustin Marquess wrote:
> >
> >
> > >     Also, is this old Slackware still a.out, or is it one of the
> > > ELF versions?  ELF can be 1-5% slower than a.out..
> >
> > This ELF slowness can be eliminated by creating statically linked
> > executables, correct?
> 
> Yes, its related to pic code used in (most) shared libraries.

When compiling with old gcc and pgcc, what does change the libs?

I can confirm the subject: beside that gcc generates smaller code,
it mostly runs faster, too (tested for gzip, bzip2, and some internal
stuff
on a PII and K6). Slightly better numbers I got when using a beast like

CC=pgcc -mamdk6
CFLAGS=-Wall -O6 -fomit-frame-pointer -fno-compare-elim -fopt-reg-stack
\
        -frecombine

because these options break the compilition or coredump:

# pgcc fail:
# -fcompare-elim -floop-after-global -fcombine-222

all at the expense of a significant bigger binary.

This really desillusionized me about the capabilities of all this
funky optimizing stuff... Mostly they are not worth the bigger size
they need (and the time figuring out the best switches). 

Real optimisation happens in the design phase of a project.
The compiler can help you getting the most of it!

Correct me, if I'm wrong.

Sorry, Marc. Please don't feel offended. As I'm an optimist, I will
look forward and see, how I can help you to get behind it...

Cheers
Hans-Peter

> --
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>       ---==---(_)__  __ ____  __       Marc Lehmann      +--
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>     The choice of a GNU generation                       |
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