This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: The arithmetic support of SCmode and DCmode.
- To: Jeffrey A Law <law at upchuck dot cygnus dot com>
- Subject: Re: The arithmetic support of SCmode and DCmode.
- From: Stephen L Moshier <moshier at mediaone dot net>
- Date: Wed, 14 Apr 1999 19:53:54 -0400 (EDT)
- cc: Toon Moene <toon at moene dot indiv dot nluug dot nl>, egcs at egcs dot cygnus dot com
- Reply-To: moshier at mediaone dot net
> > In my opinion it would be best to do the quick and dirty complex divide
> > when -ffast-math is specified, and the slow, correct one otherwise.
>That sounds like the correct approach to me.
>jeff
I believe that may violate C9X. C9X explicitly permits a fast
version of complex arithmetic, but isn't IEEE still honored while
doing so? Then it could not use fast-math. You could have a new
switch for fast-complex-math. Whoever is going to work on this ought
to look carefully at the C9X document.
In the general case neither the absolute value nor the square root can
really be fast. The likelihood of overflow in the absolute value is
vexing. I don't think there is any good reason to provide open-coded
implementations of these two functions, and I routinely disable the
existing built-in absolute value.