[OCLUG-devel] ICFP Contest 2004

[Christopher Smith]

On Wed, 2004-06-09 at 15:17, Stephen Crane wrote:
> On Wednesday, June 09, 2004 02:01 pm, you wrote:
> > On Wed, 2004-06-09 at 14:02, Stephen Crane wrote:
> > > I'm trying to understand something in the g++ compiler. If I turn on the
> > > optimization (-O1) I get a SEGFAULT almost immediatly! Any clue why this
> > > would happen? (I'm using the code attached to my original post)
> >
> > Is it your code that is SEGFAULTing, or the compiler?
> 
> Well, I tried it again and surprise, it worked. My code was segfaulting. For 
> some reason when I used the compiler in eclipse/CDT which used:
> g++ -O3 -Wall -c -o simulator.o ../simulator.cpp
> g++  -o ant_simulator     simulator.o  
> Or:
> g++ -O0 -Wall -c -o simulator.o ../simulator.cpp
> g++  -o ant_simulator     simulator.o  
> it wouldn't work, but if I used:
> g++ -Wall -o ant_simulator simulator
> It would work. Both commands apparently work now, don't know why. Any reason 
> why?

I usually start blaming the hardware if it's the compiler segfaulting,
but if it's your code, I'd use ulimit to make sure you get core dumps
and start looking at what's inside them.

It's not unusual for optimizations to expose bugs that were previously
hidden.

-- 
Christopher Smith <x at xman.org>