makecontext and its arguments

[Andreas Schwab]

Jakub Jelinek <jakub@redhat.com> writes:

|> On Mon, Aug 05, 2002 at 10:15:06PM +0200, Andreas Schwab wrote:
|> > Ulrich Drepper <drepper@redhat.com> writes:
|> > 
|> > |> Andreas Jaeger wrote:
|> > |> > That interpretation of long causes problems for x86-64 since ints are
|> > |> > not sign extented when passed in varargs...
|> > |> 
|> > |> How about fixing this mistake in the compiler with a function attribute?
|> > 
|> > ???  There is no way to find out the right type in va_arg.  Either the
|> > types match, or you get undefined behaviour.  If you pass an int and
|> > retrieve it as a long all bets are off.
|> 
|> 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?

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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