Instantiate virtual args in function-call usage

[Jeffrey A Law]

  In message < orn1d3jysw.fsf@guarana.lsd.ic.unicamp.br >you write:
  > --=-=-=
  > 
  > On Dec 30, 2000, Alexandre Oliva <aoliva@redhat.com> wrote:
  > 
  > > How about emitting memory USEs right before the call insn, and
  > > CLOBBERs right after it?
  > 
  > While I don't find time to arrange for reload to adjust MEMs in
  > CALL_INSN usage notes, here's a patch that implements this change.
  > I've been using it for a while on new port I'm working on, that makes
  > extensive use of by-reference arguments to libcalls, and apparently
  > none of its testsuite failures are caused by this patch.  Ok to
  > install?
  > 
  > 
  > --=-=-=
  > Content-Type: text/x-patch
  > Content-Disposition: inline; filename=call-lib-use-clobber-byref.patch
  > 
  > Index: gcc/ChangeLog
  > from  Alexandre Oliva  <aoliva@redhat.com>
  > 
  > 	* calls.c (emit_library_call_value_1): Emit USEs and CLOBBERs
  > 	for arguments passed by reference.
No, this is not OK.  

This needs to be fixed correctly, not hacked around by emitting extra
use/clobber insns (which in general we want to avoid anyway).

jeff