combine.c patch

[Jeffrey A Law]

  In message <199806282006.VAA15642@wildcat.demon.co.uk>you write:
  > While browsing combine.c I noticed the following, where SUBREG_REG
  > was not being applied to a SUBREG as it should be.
  > 
  > In this part of code, both op0 and op1 are of the form:
  > 
  >    (ADD:m (SUBREG:m (...)) (CONST_INT ...))
  > 
  > In both cases inner_op0 and inner_op1 are the (SUBREG:m (...)) part
  > that SUBREG_REG can validly be applied to.
  > 
  > This change causes no regressions on the i386 platform.
  > 
  >    Alasdair.
  > 
  > 
  > 
  > Sun Jun 28 20:59:35 BST 1998	Alasdair Baird	<alasdair@wildcat.demon
  > .co.uk>
  > 
  > 	* combine.c (simplify_comparison): Apply SUBREG_REG to SUBREGs.
Thanks.  I installed this patch.  I was hoping it would fix a bug recently
introduced in this code, but sadly it didn't.

jeff

ps.  This is exactly the kind of thing it would be nice to have the
RTL accessor macros check their args like we do for tree accessor
macros.  One day...... :-)