System V Application Binary Interface 0.99.5

[Michael Matz]

Hi,

On Wed, 30 Jan 2013, Andrew Haley wrote:

> I'm looking at Section 3.2.3, Parameter Passing.
> http://artfiles.org/kernel.org/pub/scm/devel/binutils/hjl/x86-64-psabi.git/
> 
> I still cannot tell whether parameters should or should not be sign- or
> zero-extended when they are moved into registers at a call.  I'm guessing
> not.

It's intentionally unspecified.

> Which is it?  This is important for interworking.

How?  You aren't allowed to access the bits outside the specified argument 
type (which must match on caller and callee side), so you can't observe 
them, so it's not required to specify their content.


Ciao,
Michael.