[Qt-interest] QPainter segmentation fault on Linux

[Christoph Bartoschek]

Davide wrote:

> That's absolutely incredible...
> I installed valgrind (I have never used this program before).
> I compiled a Debug version of my app, I run it with valgrind... And
> all work fine, NO ERROR.
> I also checked that if I run the program without valgrind I get a
> segmentation Fault.
> 
> What does it means?

Do I understand it correctly: The debug version crashes when run natively
and the debug version does not crash when run under valgrind?

This is very strange and happens very rarely. What you can do:

1. Compile an optimized version of your program but leave the debug symbols
in (-O2 -g) and then try valgrind.

2. Are you using threads? Valgrind alters the scheduling of your threads. To
check your application use heldgrind and drd on your program:
valgrind --tool=helgrind ./your_prog  and valgrind --tool=drd ./your_prog

3. Does your program depend on the accuracy of floating-point computations? 
As far as I know valgrind only supports 64bits for doubles. It does not
emulate the wider registers of some processors.

Christoph