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Message-ID: <19981020213912.G7489@cerebro.laendle>
Date: Tue, 20 Oct 1998 21:39:12 +0200
From: Marc Lehmann <pcg AT goof DOT com>
To: Steven Snyder <ssnyder AT indy DOT net>,
        pgcc mailing list <beastium-list AT Desk DOT nl>
Subject: Re: What does the -O9 switch do?
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On Tue, Oct 20, 1998 at 10:35:59AM -0500, Steven Snyder wrote:
> The pgcc Web page documents the optimizations enabled by -O3 through -O6,
> but is silent on higher optimizations.  (The gcc man pages don't mention
> anything higher than -O3.)  What, for instance, does -O9 do that -O6 does
> not?

It should do nothing more than -O6 (or -O3 for gcc). You can specify
-O69 if you want...

> Since the egcs/pgcc 1.1a compilers no longer write the switches to the
> generated asm file (can we please, please, please get that feature back?)
> there's no way to tell which flags were used in a given compilation.

Doesn't -fverbose-asm work?

> Binary files built with -O6 and -O9 do compare differently sometimes (for


I once (for a few revisions) had loop unrolling and sibling call
optimizations enabled with -O7, but that was only for a short time in the
snapshots. Otherwise the files should compare the same.

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