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Re: FWD: FLOATING-POINT CONSISTENCY, -FFLOAT-STORE, AND X86
- To: Joern Rennecke <amylaar at cygnus dot co dot uk>
- Subject: Re: FWD: FLOATING-POINT CONSISTENCY, -FFLOAT-STORE, AND X86
- From: Jamie Lokier <egcs at tantalophile dot demon dot co dot uk>
- Date: Thu, 17 Dec 1998 14:00:55 +0000
- Cc: ejr at CS dot Berkeley dot EDU, jbuck at synopsys dot com, hjstein at bfr dot co dot il, egcs at cygnus dot com
- References: <19981216010546.F7806@tantalophile.demon.co.uk> <199812170710.HAA20342@phal.cygnus.co.uk>
On Thu, Dec 17, 1998 at 07:10:51AM +0000, Joern Rennecke wrote:
> > I like this 80-bit spills idea.
> >
> > But given that you can just put the FPU into 64-bit precision mode
> > anyway to get predictable arithmetic, I would like to see the option to
> > use just 64-bit spills for those programs that do run the FPU in 64-bit
> > precision mode.
>
> The larger exponent range of 64 bit precision mode means that you still get
> inconsistent behaviour for values that are close to zero.
Ok, what I really meant was I'd like the option for the code to be fast,
if I don't care about _precise_ behaviour.
For some FP codes speed is more important than accuracy.
-- Jamie