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Message-ID:	<19980903023909.54365@cerebro.laendle>
Date:	Thu, 3 Sep 1998 02:39:09 +0200
From:	Marc Lehmann <pcg AT goof DOT com>
To:	PGCC Mailing List <beastium-list AT Desk DOT nl>
Subject:	Re: Optimizations when compiling the compiler.
Mail-Followup-To:	PGCC Mailing List <beastium-list AT Desk DOT nl>
References:	<199809030016 DOT TAA12871 AT indy1 DOT indy DOT net>
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In-Reply-To:	<199809030016.TAA12871@indy1.indy.net>; from Steve Snyder on Wed, Sep 02, 1998 at 08:13:29PM -0500
X-Operating-System:	Linux version 2.1.119 (root AT cerebro) (gcc version pgcc-2.91.57 19980901 (egcs-1.1 release))
Status:	RO
Lines:	32

On Wed, Sep 02, 1998 at 08:13:29PM -0500, Steve Snyder wrote:
> In a recent message it was noted that the most dramatic improvements to
> Pentium-optimized code require the -O5 and -O6 switches.  This make me
> wonder:  what optimization setting were used in testing the pgcc 1.1
> release candidates?
> 
> I spend a *lot* of time running my C compiler, so naturally I want it to
> run as fast as possible.  Also, naturally, I want the compiler to be
> stable.  I get enough instability in my own code.  :-)
> 
> So... how risky is it for me to compile pgcc 1.1a with itself, using the
> -O5 or -O6 optimization switches?  That is, how much would I be reducing 
> the dependability of compiler, as opposed to building it with itself at an 
> optimization level of -O3 or -O4?

I've run, for years, an -O6 -fno-omit-frame-pointer optimized version, until
I forgot about it.

then it bite me, sicne then, I compile pgcc with -V2.7.2 -O2. I also don't
support compilers compiled with -O6, the chance of them being broken
(undebuggable..) is too high.

I believe it should be quite safe to use -O6 on pgcc in the 1.0/1.1
releases, but don't count on that...

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      ---==---(_)__  __ ____  __       Marc Lehmann       +--
      --==---/ / _ \/ // /\ \/ /       pcg AT goof DOT com       |e|
      -=====/_/_//_/\_,_/ /_/\_\                          --+
    The choice of a GNU generation                        |
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