SUBREGs

[Jeffrey A Law]

Note I've moved this to egcs@cygnus.com.

  In message <199809150945.KAA03265@phal.cygnus.co.uk>you write:
  > > The fix is to change the representation.  I've decided that the
  > > cleanest thing to do is to change SUBREG_WORD() to SUBREG_BIT().  Then
  > > perhaps one more macro defined by the target macros which tells
  > > the correspondance between hard regno and bit sizes.
  > ...
  > > Nevertheless I would like to hear some feedback from others
  > 
  > Using bits as the basic unit can lead to problems if you want to describe
  > a member of a struct that is larger than 1/8th of the address space.
  > It would be safer to use addressable units (for most targets, that's bytes).
  > 
  > Even then, we have to be aware that only an unsigned quantity can
  > be relied on to describe the size of an object that is larger than
  > one half of the address space.
I don't think we have to worry about such large values being held in
a SUBREG/REG.  Seriously, do we really forsee a REG/SUBREG with a
size that approaches 1/8 of the address space for the target?  That's
a little absurd.

jeff