Re: REG_UNUSED notes problem

[Jeffrey A Law <law at cygnus dot com>]

  In message <199812091142.LAA24541@phal.cygnus.co.uk>you write:
  > > Since there is no REG_UNUSED note attached to insn 47, the m68k backend
  > > will generate code which sets %d0.  And we lose since (reg 0) is actually
  > > expected to hold part of an address (remember, we had a REG_UNUSED note f
  > or
  > > the original pseudo in the divmod insn, so the compiler can and does assu
  > me
  > > that nothing is written to that unused value).
  > 
  > Huh?  That is wrong.  The compiler has to assume that the register is
  > clobbered.
  > So it is a reload bug that reg 0 was used for the reload.
  > I guess that the problem stems from single_set returning the set of reg
  > 42, and the caller then checking only for clobbers, but not for unused
  > sets.
It seems to me with the REG_UNUSED note on that insn reload should be free to
use (reg 0) in any way it wants.



jeff