From mboxrd@z Thu Jan  1 00:00:00 1970
From: Veksler Michael <mveksler@technion.ac.il>
To: help-gcc@gnu.org
Subject: Re: Over optimisation
Date: Sun, 31 Oct 1999 13:57:00 -0000
Message-ID: <7t80u4$5mk$1@techftp.technion.ac.il>
References: <01bf05ce$5ca544c0$4f7fa890@us1.lincoln.msl.mitel.com>
X-SW-Source: 1999-10n/msg00036.html
Message-ID: <19991031135700.O7Oy_AiEUyPw43yzNxkSmwoI89otkOoXAtRT7-G1xZs@z>

Andrew Davies <Andrew_Davies@Xmitel.com> wrote:
>  Hi,
>  	I have a problem with the optimiser. When I compile the following test
>  loop:
>
>  do  {
>      test = regbase->utx & 0x8000;
>      }while(test == 0x0000);

[snip]

>  I think the optimiser is assuming the line inside the do while loop is
>  static and therefore removes it from the loop. As a result it gets stuck.
>  Anyone know how to solve this without turning the optimiser off? 

The optimizer is right, unless you declare regbase volatile. Otherwise,
the compiler has a right to assume that no one is modifying 'regbase'.

  Michael