EGCS Optimisation??

Richard Lyon
Wed Dec 16 07:56:00 GMT 1998

Yes I will do these things. I don't want anyone to waste time if there isn't
a 'real' problem.

It is fantastic to have the simulator running under NT. We are hoping to
make cygwin the preferred port for omnetpp. My university is beginning to
adopt omnetpp in preferance to opnet. Having cygwin available makes it
feasible for students to run omnetpp without having to buy another compiler.

I enjoy using cygwin and are most impressed.

-----Original Message-----
From: Mumit Khan <khan@xraylith.wisc.EDU>
To: Richard Lyon <>
Cc: <>
Date: Tuesday, 15 December 1998 17:28
Subject: Re: EGCS Optimisation??

>"Richard Lyon" <> writes:
>> Hi,
>> I am working on porting the omnetpp discrete-event simulator to cygwin.
>> 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
>> 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
>> 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 on how to do so.
>I'll be willing to take a quick look if you can bundle it all up.

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