re PR tree-optimization/23817 (ICE in check_loop_closed_ssa_use, at tree-ssa-loop-manip.c:398)

	PR tree-optimize/23817
	* tree-cfg.c (tree_merge_blocks): Preserve loop closed ssa.

From-SVN: r104218

gcc/ChangeLog

+2005-09-13  Zdenek Dvorak  <dvorakz@suse.cz>
+
+	PR tree-optimize/23817
+	* tree-cfg.c (tree_merge_blocks): Preserve loop closed ssa.
+
 2005-09-13  Alan Modra  <amodra@bigpond.net.au>
 
 	PR target/23774

gcc/tree-cfg.c

@@ -1314,8 +1314,17 @@ tree_merge_blocks (basic_block a, basic_block b)
     {
       tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
       tree copy;
-      
-      if (!may_propagate_copy (def, use))
+      bool may_replace_uses = may_propagate_copy (def, use);
+
+      /* In case we have loops to care about, do not propagate arguments of
+	 loop closed ssa phi nodes.  */
+      if (current_loops
+	  && is_gimple_reg (def)
+	  && TREE_CODE (use) == SSA_NAME
+	  && a->loop_father != b->loop_father)
+	may_replace_uses = false;
+
+      if (!may_replace_uses)
 	{
 	  gcc_assert (is_gimple_reg (def));