loop.c (strength_reduce): Don't move giv insn for biv turned giv below scan_start.

	* loop.c (strength_reduce): Don't move giv insn for biv turned giv
	below scan_start.

From-SVN: r25264

gcc/ChangeLog

+Wed Feb 17 16:59:28 1999  J"orn Rennecke <amylaar@cygnus.co.uk>
+
+	* loop.c (strength_reduce): Don't move giv insn for biv turned giv
+	below scan_start.
+
 Wed Feb 17 10:56:24 1999  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* tree.c (tree_node_kind_names, print_obstack_name,

gcc/loop.c

@@ -4053,6 +4053,7 @@ strength_reduce (scan_start, end, loop_top, insn_count,
 	      /* We can get better optimization if we can move the giv setting
 		 before the first giv use.  */
 	      if (dominator
+		  && ! loop_insn_first_p (dominator, scan_start)
 		  && ! reg_set_between_p (bl2->biv->src_reg, loop_start,
 					  dominator)
 		  && ! reg_used_between_p (giv, loop_start, dominator)