Subject: Re: I want to rid ugly float load/stores used only for data movement
To: Jason R Thorpe <firstname.lastname@example.org>
From: None <email@example.com>
Date: 03/03/2003 00:27:17
> On Sat, Feb 22, 2003 at 06:09:13PM -0500, David Edelsohn wrote:
> > MLR> Would anyone point me in the correct direction?
> > Your intent cannot be implemented safely in GCC. If GCC knows it
> > has FPRs and FPRs hold 64-bit values (which they must), it will use them
> > for 64-bit moves. Cannot be avoided safely.
> That's kind of a bummer. I seem to recall the idea of "no-implicit-fp"
> coming up on the GCC mailing list recently, too. The reason people want
> is to eliminate unpredictable context switch times and/or speed up context
Yes. Check GCC's CVS and I think you will find that this is fixed.
This "implicit FP" stuff was causing trouble on VxWorks; Wind River raised
this issue with the FSF.
As I recall, the decision was to abandon this sly use of FP registers.
So, at some point, bringing in a new GCC should fix it.
BTW, Mouse: GCC already avoids this tactic on chips for which FP registers
do not hold arbitrary values (i386, m68k, to name a couple). Please, give
them _some_ credit.
toddpw @ toddpw.org