From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Hubicka <jh@suse.cz>
To: Brad Lucier <lucier@math.purdue.edu>
Cc: Jan Hubicka <jh@suse.cz>, Alexandre Oliva <aoliva@redhat.com>, Joe Buck <jbuck@synopsys.COM>, Chris Lattner <sabre@nondot.org>, gcc@gcc.gnu.org
Subject: Re: floor on i386
Date: Tue, 25 Sep 2001 08:00:00 -0000
Message-id: <20010925170025.H13734@atrey.karlin.mff.cuni.cz>
References: <20010925154659.B13734@atrey.karlin.mff.cuni.cz> <200109251447.f8PEl2E05637@banach.math.purdue.edu>
X-SW-Source: 2001-09/msg00986.html

> > Major problem still remains in reload.
> > If we don't want to get exact IEEE by setting proper precisity before each
> > mathematic operation (as SH4 does IMO), we will run into problems with spills ,
> > since these can be put in place control word is set to some wrong value
> > resutlting in wrong rounding before storing.
> 
> If spills spilled the extended precision value, which is needed
> anyway for proper IEEE conformance, this wouldn't be an issue.

Yes, but it is big performance problem when done, at least for AMD CPUs, where
XFmode spills cost a lot more than DF/or SFmode, so it should not be enabled unconditionally.
(I was trying to implement this idea in the past and it appears to be quite dificult to do
too :( )

Honza
> 
> Brad