Fix for elimination within SUBREG bug

[kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)]

This is part of the fix for the bug I recently raised on the GCC list.
I think more cleanup is needed, but am not sure exactly what.  This fixes
the problem (compiling md5 on Sparc64 for VxWorks) and bootstraps on
Alphaev56.  This may be a regression from GCC 2.95, but probably isn't
worth doing anything about.

Sun Jun  3 21:59:51 2001  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>

	* reload.c (reload_inner_reg_of_subreg): Return 1 for PLUS.
	(push_reload): Handle non-REG in reload_inner_reg_of_subreg case.

*** reload.c	2001/05/01 12:11:33	1.146
--- reload.c	2001/06/04 00:10:37
*************** reload_inner_reg_of_subreg (x, mode)
*** 781,786 ****
    inner = SUBREG_REG (x);
  
!   /* If INNER is a constant, then INNER must be reloaded.  */
!   if (CONSTANT_P (inner))
      return 1;
  
--- 782,787 ----
    inner = SUBREG_REG (x);
  
!   /* If INNER is a constant or PLUS, then INNER must be reloaded.  */
!   if (CONSTANT_P (inner) || GET_CODE (inner) == PLUS)
      return 1;
  
*************** push_reload (in, out, inloc, outloc, cla
*** 1031,1034 ****
--- 1032,1045 ----
    if (in != 0 && reload_inner_reg_of_subreg (in, inmode))
      {
+       enum reg_class in_class = class;
+ 
+       if (GET_CODE (SUBREG_REG (in)) == REG)
+ 	in_class
+ 	  = find_valid_class (inmode,
+ 			      subreg_regno_offset (REGNO (SUBREG_REG (in)),
+ 						   GET_MODE (SUBREG_REG (in)),
+ 						   SUBREG_BYTE (in),
+ 						   GET_MODE (in)));
+ 
        /* This relies on the fact that emit_reload_insns outputs the
  	 instructions for input reloads of type RELOAD_OTHER in the same
*************** push_reload (in, out, inloc, outloc, cla
*** 1036,1046 ****
  	 RELOAD_OTHER, we are guaranteed that this inner reload will be
  	 output before the outer reload.  */
!       push_reload (SUBREG_REG (in), NULL_RTX, &SUBREG_REG (in), (rtx*)0,
! 		   find_valid_class (inmode,
! 				     subreg_regno_offset (REGNO (SUBREG_REG (in)),
! 							  GET_MODE (SUBREG_REG (in)),
! 							  SUBREG_BYTE (in),
! 							  GET_MODE (in))),
! 		   VOIDmode, VOIDmode, 0, 0, opnum, type);
        dont_remove_subreg = 1;
      }
--- 1047,1052 ----
  	 RELOAD_OTHER, we are guaranteed that this inner reload will be
  	 output before the outer reload.  */
!       push_reload (SUBREG_REG (in), NULL_RTX, &SUBREG_REG (in), NULL_RTX,
! 		   in_class, VOIDmode, VOIDmode, 0, 0, opnum, type);
        dont_remove_subreg = 1;
      }