[GCC 4.2 Project] Omega data dependence test

[Sebastian Pop]

Joe Buck wrote:
> Algorithms that are sometimes exponential can still be used if there is
> a cutoff mechanism, to abort the algorithm if it exceeds a budget.  This
> assumes that we can then fall back to an algorithm that might produce
> inferior results, but will produce something usable in reasonable time.
> 

Okay, I stand corrected.  As a practical implementation we can have a
mechanism as push/pop timevar, that would monitor the time and space
of an algorithm and that can cancel the computation for failing on a
safe approximation.  As a first concretization, I was thinking to use
threads, but I'm not sure whether this is suitable for GCC.