patch applied to loop.c

[Joern Rennecke]

I have separately tested (with an x86 bootstrap) and re-applied this patch:

Mon Aug  2 23:46:45 1999  J"orn Rennecke <amylaar@cygnus.co.uk>

	* loop.c (strength_reduce): When doing biv->giv conversion, fix up
	reg_biv_class.

Index: loop.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/loop.c,v
retrieving revision 1.168
diff -p -r1.168 loop.c
*** loop.c	1999/07/09 03:34:21	1.168
--- loop.c	1999/08/02 22:47:02
*************** strength_reduce (scan_start, end, loop_t
*** 4072,4077 ****
--- 4072,4078 ----
  		fprintf (loop_dump_stream, "is giv of biv %d\n", bl2->regno);
  	      /* Let this giv be discovered by the generic code.  */
  	      REG_IV_TYPE (bl->regno) = UNKNOWN_INDUCT;
+ 	      reg_biv_class[bl->regno] = NULL_PTR;
  	      /* We can get better optimization if we can move the giv setting
  		 before the first giv use.  */
  	      if (dominator
*************** strength_reduce (scan_start, end, loop_t
*** 4123,4129 ****
  		}
  	      /* Remove this biv from the chain.  */
  	      if (bl->next)
! 		*bl = *bl->next;
  	      else
  		{
  		  *backbl = 0;
--- 4124,4136 ----
  		}
  	      /* Remove this biv from the chain.  */
  	      if (bl->next)
! 		{
! 		  /* We move the following giv from *bl->next into *bl.
! 		     We have to update reg_biv_class for that moved biv
! 		     to point to its new address.  */
! 		  *bl = *bl->next;
! 		  reg_biv_class[bl->regno] = bl;
! 		}
  	      else
  		{
  		  *backbl = 0;