Re: [RFC] potential fix for PR middle-end/7151

["David S. Miller" <davem at redhat dot com>]

   From: Richard Henderson <rth@redhat.com>
   Date: Tue, 1 Oct 2002 12:50:25 -0700

   On Mon, Sep 30, 2002 at 09:33:06PM -0700, David S. Miller wrote:
   > +  else if ((in_regnum = true_regnum (in)) >= 0
   
   I didn't think you could use true_regnum this early.
   I know it get some of its data from reload itself, and
   we're in the middle some place.
   
At this point, since we are generating reloads, allocate_reg_info()
must have run already to allocate reg_renumber.  Unallocated
pseudo register slots in reg_renumber[] will be preinitialized
to -1.

I don't see any problems.

   Is this problem related to 
   
     http://gcc.gnu.org/ml/gcc-patches/2002-08/msg01539.html
   
Same bug, but his patch assumes SUBREG_REG is a REG, it could
be a MEM.  Actually, so does true_regnum() so my patch has
the same bug if it is a bug.

Can we see GET_CODE (SUBREG_REG (x)) == MEM when generating
reloads?  Upon further reading, it appears not.

So, if SUBREG_REG can be assumed to be REG here, Jan's patch
is fine and solves my problem too.