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Re: Optimisation prevents overflow?
- From: Brooks Moses <bmoses at stanford dot edu>
- To: Daniel Franke <franke dot daniel at gmail dot com>
- Cc: fortran at gcc dot gnu dot org, Davide Mancusi <arekfu at yahoo dot it>
- Date: Thu, 19 Jul 2007 14:42:06 -0700
- Subject: Re: Optimisation prevents overflow?
- References: <469FD202.7080407@yahoo.it> <200707192335.15396.franke.daniel@gmail.com>
On Thu, Jul 19, 2007 at 11:35:15PM +0200, Daniel Franke wrote:
> On Thursday 19 July 2007 23:05:06 Davide Mancusi wrote:
> > Is optimisation preventing overflow? What is really happening here?
>
> In other mail:
> > ...and yes, -ffloat-store fixes it. What does it do? I could not find
> > documentation about it.
>
> I'd guess, that's the (in)famous extended precision, 80 vs. 64 bits (iirc).
Yeah, I thought so at first, but those both have the same exponent range
IIRC, and certainly not enough to get up to an erroneous answer of 273
instead of 18 before it overflows.
- Brooks