[RFC]: Argument setup for sibcalls

[John David Anglin]

When FUNCTION_INCOMING_ARG is defined, it is used to set up the outgoing
arguments for sibling calls.  This is the cause of the problem noted in
PR 10271.  On the PA, FUNCTION_ARG and FUNCTION_INCOMING_ARG have been
used for many years to distinguish outgoing and incoming arguments.
However, if FUNCTION_INCOMING_ARG is to be used for both incoming and
outgoing arguments, I need to come up with a different way to do this.

Is the use of FUNCTION_INCOMING_ARG for outgoing sibcall arguments correct?

Alan Modra hit the same problem as that in PR 10271 doing some development
work on the powerpc.  He suggested that we might want a new macro
SIBCALL_FUNCTION_ARG.

There are several ports that define FUNCTION_INCOMING_ARG.  I believe
that FUNCTION_INCOMING_ARG was used to obtain the correct sibcall
argument setup on the sparc.  However, it's not clear whether the
current sibcall argument setup is correct on the other ports.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)