[ODE] SIGSEGV in dSolveLCP() at ode/src/lcp.cpp:1137

[Olivier Michel]

Hi,

Here is a first version of the ALLOCA replacement by dynamic memory 
allocation (currently malloc/free):

http://cyberboticspc1.epfl.ch/ftp/ode.tar.bz2

I just added a compiler switch in the user-settings.example (disabled by 
default) which allow to replace the ALLOCA by malloc/free calls in the 
patched lcp.cpp file only (this is actually the most critical source of 
stack overflow).

The ode.tar.bz2 archive only contains new versions for:

config/user-settings.example
Makefile
ode/src/lcp.cpp

This contribution is just a first version and could be improved with the 
following:

(1) use faster functions to replace the vanilla malloc() / free() 
functions.
(2) generalize the replacement of ALLOCA in other files (like step.cpp, 
stepfast.cpp, etc.). The current version only replace the ALLOCA in 
lcp.cpp and this appears as a nice trade-off between efficiency and 
stability (not SIGSEGV any more with my pretty complex simulation and a 
very little performance drop). So, be cautious if you want to extend the 
use of malloc/free to other files as this may yield to serious 
performance drops...

This contribution is very simple and early. However, I hope it could be 
introduced in the ODE CVS right now since it doesn't change anything if 
the switch is not set (default) and it will save a lot of time to 
developers facing the SIGSEGV crash caused by stack overflow...

Thanks.

-Olivier