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Re: makecontext and its arguments

Jakub Jelinek <jakub@redhat.com> writes:

|> On Mon, Aug 05, 2002 at 10:29:55PM +0200, Andreas Schwab wrote:
|> > |> Adding __attribute__((sane_x86_64_varargs)) to makecontext and make gcc
|> > |> promote all varargs into DImode when calling vararg functions with
|> > |> this attribute?
|> > 
|> > How do you know whether you are supposed to sign extend or not?
|> 
|> If the type of the argument passed to vararg function is signed, you
|> sign extend, otherwise zero extend. That's what all other 64-bit ABIs do.

How does that help in any way?  If you pass an unsigned int to
makecontext it is not supposed to be signed extended, but zero extended
when assigned to long.  There is no way for va_arg to know that.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
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