[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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