Re: Preventing gcc from aligning stack???

From: Horst von Brand (vonbrand@sleipnir.valparaiso.cl)
Date: Sat Jan 29 2000 - 13:56:19 EST


Jamie Lokier <lkd@tantalophile.demon.co.uk> said:
> Stefan Monnier wrote:
> > >>>>> "H" == H Peter Anvin <hpa@transmeta.com> writes:
> > > ICK. I'd really like to see a version which spilled to extended
> > > precision.

> > Why should gcc spill a double (i.e. 64bit) as extended precision ?

> So that the behaviour of a program does not depend on whether a register
> is spilled. So that you get consistent results from the same code.

Floationg point code is by its very nature inexact. To force "exactness" on
it (at the cost of a very sizable performance loss) is not very
realistic. Anyway, it's in the end a flaw in the design of the ia32.

[...]

> Numerical codes, simple things like minimum finders and iterative
> solvers, depend on such behaviour.

How? An example, please.

-- 
Horst von Brand                             vonbrand@sleipnir.valparaiso.cl
Casilla 9G, Viņa del Mar, Chile                               +56 32 672616

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