[Bug lto/44334] rnflow.f90 ~27% slower with -fwhole-program -flto after revision 159852

[jh at suse dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44334

--- Comment #46 from jh at suse dot de 2011-01-25 17:57:38 UTC ---
I sorted out increasing large function growth ratio as most safe way  
to deal with (easier half of) this problem. Unlike the parameters for  
inline limits it won't cause code size issues. It just allow somewhat  
bigger functions and thus stress more the backend on its linearity.

Given that the parameter was never tuned since its inclusion in GCC  
4.2, I guess we are not terribly sensitive here. We also improved a  
bit in the scalability here as I tuned the df code bit for LTO and  
spagetti code.

Otherwise we need to wait for 4.7 or possibly 4.6.1. That is fine with me.
I will still run tests tonight on how increasing the parameter affect  
our tester.  This is first time I see it hit in perfomrance sensitive  
way. Not sure how common it is in practice since I never really tried  
to change it.