Petr Savicky wrote: > With "gcc -mfpmath=sse -msse" I obtained no warning/error, but the program > behaves in the old wrong way. Try with -O2 and you'll see vastly different results. Without any -O you're telling gcc not to do any optimization whatsoever, and many, many passes are just never run in that case so lots of stuff won't work. It's possible that none of -mfpmath or -ffast-math or -ffloat-store or -mpc32/-mpc64/-mpc80 et al. don't work without optimization passes enabled. But you'd have to look at the code and documentation to find out for sure. Brian
