Floating point performance

Simon Marlow simonmar@microsoft.com
Mon, 29 Jan 2001 13:25:36 -0000

> Fri, 26 Jan 2001 17:40:17 +0100, Jan Kort <kort@wins.uva.nl> pisze:
> > I made a profile and it says most of the time (93%) is spent in
> > the function bar.
> Did you compile with optimization turned on (option -O)?
> I see similar results without -O but quite different with -O.

Without optimisation, you get the native code generator which produces
particularly brain-dead code for floating point on x86 (mainly due to
Intel's brain-dead design of the x86 floating point unit).  With
optimisation, you get gcc.