branch patch for loop problems

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

Opps.  Hit the wrong button.

Basically we've got a patch for 990513-1.c and some related problems, but
the patch is a little more complex than I'd like for the gcc-2.95 branch.

I've disabled the offending optimization in the branch only.  I will iterate
with Joern to get the real fix into the mainline sources.

I'm *hoping* this will also fix some libstdc++ & libg++ regressions on the
sparc.  I'll know more about them later.

	* loop.c (strength_reduce): Disable biv->giv translations and
	giv recombination.  For the release branch only.

Index: loop.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/loop.c,v
retrieving revision 1.156.4.5
diff -c -3 -p -r1.156.4.5 loop.c
*** loop.c	1999/06/09 22:39:44	1.156.4.5
--- loop.c	1999/06/10 06:42:51
*************** strength_reduce (scan_start, end, loop_t
*** 4134,4141 ****
      n_extra_increment += bl->biv_count - 1;
  
    /* If the loop contains volatile memory references do not allow any
!      replacements to take place, since this could loose the volatile 
markers.  */
!   if (n_extra_increment  && ! loop_has_volatile)
      {
        int nregs = first_increment_giv + n_extra_increment;
  
--- 4134,4148 ----
      n_extra_increment += bl->biv_count - 1;
  
    /* If the loop contains volatile memory references do not allow any
!      replacements to take place, since this could loose the volatile
!      markers.
! 
!      Disabled for the gcc-2.95 release.  There are still some problems with
!      giv recombination.  We have a patch from Joern which should fix those
!      problems.  But the patch is fairly complex and not really suitable for
!      the gcc-2.95 branch at this stage.  */
!   if (0 && n_extra_increment  && ! loop_has_volatile)
! 
      {
        int nregs = first_increment_giv + n_extra_increment;
  
*************** strength_reduce (scan_start, end, loop_t
*** 4740,4746 ****
--- 4747,4759 ----
  	  VARRAY_GROW (reg_iv_type, nregs);
  	  VARRAY_GROW (reg_iv_info, nregs);
  	}
+ #if 0
+       /* Disabled for the gcc-2.95 release.  There are still some problems 
with
+ 	 giv recombination.  We have a patch from Joern which should fix those
+ 	 problems.  But the patch is fairly complex and not really suitable for
+ 	 the gcc-2.95 branch at this stage.  */
        recombine_givs (bl, loop_start, loop_end, unroll_p);
+ #endif
  
        /* Reduce each giv that we decided to reduce.  */