Re: PATCH: extra machine-dependent passes

[law at redhat dot com]

  In message <jmhexh4csv.fsf@geoffk.org>you write:
  > DJ Delorie <dj@redhat.com> writes:
  > 
  > > > I think you need to describe the issue to the folks on the gcc list
  > > > before they can properly evaluate this patch.
  > > 
  > > OK, here's the background: The port I'm working on has a few registers
  > > that are similar to the MIPS gp register, but because of a shortage of
  > > registers, they must be available for general use also.  So, I emit a
  > > move to a pseudo at the beginning of the function, much like the alpha
  > > saves it's return address register, to keep track of that value.
  > 
  > This sounds like something that would be useful in other ports than
  > yours.  Just about every port has a registers like this for doing PIC,
  > and there are lots of ports with few registers available (for
  > instance, x86 has both properties).  Can you implement this is a
  > generic way?
  > 
  > It sounds like this would be best done at about the time of
  > instantiate_virtual_regs; it's really just passing a hidden argument
  > to the function.
If we really need something like this, then let's write a pass to do it,
not insert the pre-alloc hook DJ suggested which is big enough to drive
a mac truck through.


jeff