From: khan AT xraylith DOT wisc DOT edu (Mumit Khan)
Subject: Re: EGCS Optimisation??
15 Dec 1998 10:14:35 -0800
Message-ID: <199812150628.AAA13136.cygnus.gnu-win32@modi.xraylith.wisc.edu>
References: <000601be276a$ff95b310$71466ccb AT rlyon>
To: "Richard Lyon" <rlyon01 AT ozemail DOT com DOT au>
Cc: gnu-win32 AT cygnus DOT com

"Richard Lyon" <rlyon01 AT ozemail DOT com DOT au> writes:
> Hi,
> 
> I am working on porting the omnetpp discrete-event simulator to cygwin. The
> port is basically complete, with exception that some of the code won't
> compile correctly when I turn on compiler optimisations. The simulator
  ^^^^^^
  (I'm assuming that you mean execute here).
 
> startup modules compile and run with option -O0. But, when I turn on the
> most basic optimisation -O1, the simulator executable dies with a status
> access violation exception. Quickly checking with gdb, shows that some code
> is running which should not be reachable. Manually
> selecting -fthread-jumps, -fdefer-pop -fomit-frame-pointer doe not causes
> any problems. I am using 20.1 on winnt 4.0 and SP4.
> 
> When -O1 is selected, what other optimisations are turned on? The gcc info
> pages do not specify all
> optimisations that are activated by -O1.

There is always the chance that you're tweaking a bug in the optimizer,
but I strongly recommend that you first run your code through a memory 
debugger (Purify is what I use, but ElectricFence can also help find most 
of the usual problems) first.

If that doesn't show anything in your code, time to file a bug report.
Please see http://egcs.cygnus.com/faq.html#bugreport on how to do so. 
I'll be willing to take a quick look if you can bundle it all up.

Regards,
Mumit

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