Re: Simple recompute_reg_usage cleanup

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

  In message <19991204134435.48091@atrey.karlin.mff.cuni.cz>you write:
  > > > The VTOP notes only seem to be used by loop.c and reorg.c and in both
  > > > cases they are only used to guess program flow which we can determine
  > > > more accurately from the CFG.
  > > 
  > > No, loop also wants to know if the loop condition has already been evalua
  > ted
  > > for the first iteration, yielding true.
  > > I.e. VTOP also says something about the range of values that the
  > > iteration varaible can hold.
  > > 
  > Aha. 
  > What prevents us from doing the exit test duplication after loop?
  > (I.e remove it from jump pass and do it as the last think in loop pass?)
  > (quick searching says that jump is the only setter of this note, so
  > this ought not to be problem)
Among other things cse1 & gcse won't see that code.  I don't know how important
that actually is though.
jeff