From: elf AT netcom DOT com (Marc Singer)
Message-Id: <199605281736.KAA02300@netcom16.netcom.com>
Subject: Re: pentium-gcc
To: alla AT lysator DOT liu DOT se (Alexander Larsson)
Date: Tue, 28 May 1996 10:35:54 -0700 (PDT)
In-Reply-To: <31AAA608.32@lysator.liu.se> from "Alexander Larsson" at May 28, 96 00:06:48 am
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Sender: elf AT netcom DOT com

> 
> Today i downloaded the pentium gcc 2.7.2 
> patchlevel 19 and succesfully compiled it.
> But When i compiled a program (begining of a 
> vector graphics engine) and compiled it with
> -mpentium -O6 it actually ran slower than with 
> -m486 -O2.
> 
> I don't know why. have anyone tried this with other 
> results?
> 
> I have a pentium overdrive 83Mhz, isn't it exactly like
> a pentium?
> 
> The program i ran might not be good  for comparison, i'll
> try some other program tomorrow. Gotta sleep now.

Did you get this compiler from the Compiler Group web site?  You may
want to look at the assembler code and examine how the optimizations
affect code organization.  It could be that either the compiler was
not produced by the Compiler Group (not their full title, but this is
part of it) which means that it may be broken IMHO, or it could be a
problem with the CPU cache and lack there-of on your machine.  The
Pentium code stream could be longer, enough such that the cache is too
small to contain the critical loop.

Marc Singer