[gambit-list] Experience with the new compile options

Bradley Lucier lucier at math.purdue.edu
Tue Aug 7 11:31:04 EDT 2007


Marc:

I've had a lot of experience now with the new compile options (and  
I'm not talking about --enable-gcc-opts) and I have to say that they  
just aren't worth it.  You don't know which of them help the most in  
execution time, and you don't know which cost the most in compile  
time.  (Hell, you don't even know which ones help *at all*; you could  
be running compiler passes that hurt run-time performance while  
eating up compile time.)

You ran a genetic algorithm to guess which optimizations to run.   
That's fine to get an idea of what to try, but it's not sufficient to  
foist this pain on your users.  Even on my Opteron server development  
is painful.

So pull back to the old

-O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math -fno-strict- 
aliasing -fwrapv -fomit-frame-pointer

by default; even offer a configure optimization to add - 
D___OPTIMIZE_SPACE to the compile line.  You have a development model  
that does whole-program compilation by default; it just can't support  
the default compiler options chosen at configure time.

Brad



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