From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Moxham <jlm@maths.soton.ac.uk>
To: gcc@gcc.gnu.org
Subject: aliasing
Date: Tue, 31 Aug 1999 23:20:00 -0000
Message-ID: <199908211622.RAA18934@malone.maths.soton.ac.uk>
X-SW-Source: 1999-08n/msg00645.html
Message-ID: <19990831232000.w8EotH24xaxDquCaqvGjggVUYwypIWNzr3qcoJMnXqs@z>

I have a C++ ( really a C prog with a couple of overloaded fn's )
program which I'm fairly sure breaks the strict aliasing rules of
Gcc-2.95.1 

Where can find a copy of what these rules are , so I can fix my code ?


For a temporary fix I added -fno-strict-aliasing to the options and
expected a performance drop . However the program now runs 1% faster ???
(I assure you 1% is not a trival amount)

Using Slackware 3.9 + gcc 2.95.1 on AMD K6(x86)
options -O3 -fno-exceptions -funroll-loops -march=k6
-fomit-frame-pointer -ffast-math   ... etc

I can send 
source(100K) + exe's(50K) + data  etc.. 


Jason Moxham
jlm@maths.soton.ac.uk