From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joe Buck <jbuck@Synopsys.COM>
To: burley@gnu.org (Craig Burley)
Cc: moshier@mediaone.net, egcs@cygnus.com, burley@gnu.org
Subject: Re: FLOATING-POINT CONSISTENCY, -FFLOAT-STORE, AND X86
Date: Mon, 14 Dec 1998 09:25:00 -0000
Message-id: <199812141723.JAA02195@atrus.synopsys.com>
References: <199812141649.LAA28621@melange.gnu.org>
X-SW-Source: 1998-12/msg00480.html

What would the performance cost be if we spilled ix86 FP registers
as 80 bits?  Unfortunately I'm not familiar enough with the ix86
instruction set to answer this question for myself.  How difficult
would it be to change gcc to do 80 bit spills, without changing
the size of float and double?

It seems to me that it should cost a lot less than -ffloat-store
and should get rid of the unpredictable behavior.  (Yes, it still
doesn't match IEEE unless more is done, but it stops weirdness like
root-finding algorithms that fail to converge if you're unlucky).