* tree-scalar-evolution.c (scev_const_prop):

	* tree-phinodes.c (remove_phi_node): Add argument
	RELEASE_LHS_P.  If given, release the SSA name on the LHS of
	the PHI node.
	Update all users.
	* tree-ssa-dce.c: Remove forward declarations for static
	functions.  Re-arrange functions bodies as needed.
	(find_obviously_necessary_stmts): Never mark PHI nodes as
	obviously necessary.

From-SVN: r119740

gcc/ChangeLog

+2006-12-11  Diego Novillo  <dnovillo@redhat.com>
+
+	* tree-scalar-evolution.c (scev_const_prop):
+	* tree-phinodes.c (remove_phi_node): Add argument
+	RELEASE_LHS_P.  If given, release the SSA name on the LHS of
+	the PHI node.
+	Update all users.
+	* tree-ssa-dce.c: Remove forward declarations for static
+	functions.  Re-arrange functions bodies as needed.
+	(find_obviously_necessary_stmts): Never mark PHI nodes as
+	obviously necessary.
+
 2006-12-11  Carlos O'Donell  <carlos@codesourcery.com>
 
 	* config/arm/elf.h (MAX_OFILE_ALIGNMENT): Remove definition.

gcc/lambda-code.c

@@ -2474,13 +2474,9 @@ perfect_nestify (struct loop *loop,
     }
   e = redirect_edge_and_branch (single_succ_edge (preheaderbb), headerbb);
 
-  /* Remove the exit phis from the old basic block.  Make sure to set
-     PHI_RESULT to null so it doesn't get released.  */
+  /* Remove the exit phis from the old basic block.  */
   while (phi_nodes (olddest) != NULL)
-    {
-      SET_PHI_RESULT (phi_nodes (olddest), NULL);
-      remove_phi_node (phi_nodes (olddest), NULL);
-    }      
+    remove_phi_node (phi_nodes (olddest), NULL, false);
 
   /* and add them back to the new basic block.  */
   while (VEC_length (tree, phis) != 0)

gcc/tree-cfg.c

@@ -1333,13 +1333,12 @@ tree_merge_blocks (basic_block a, basic_block b)
 	     appear as arguments of the phi nodes.  */
 	  copy = build2_gimple (GIMPLE_MODIFY_STMT, def, use);
 	  bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
-	  SET_PHI_RESULT (phi, NULL_TREE);
 	  SSA_NAME_DEF_STMT (def) = copy;
 	}
       else
 	replace_uses_by (def, use);
 
-      remove_phi_node (phi, NULL);
+      remove_phi_node (phi, NULL, false);
     }
 
   /* Ensure that B follows A.  */
@@ -1970,7 +1969,7 @@ remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
   while (phi)
     {
       tree next = PHI_CHAIN (phi);
-      remove_phi_node (phi, NULL_TREE);
+      remove_phi_node (phi, NULL_TREE, true);
       phi = next;
     }
 

gcc/tree-flow.h

@@ -687,7 +687,7 @@ extern void reserve_phi_args_for_new_edge (basic_block);
 extern tree create_phi_node (tree, basic_block);
 extern void add_phi_arg (tree, tree, edge);
 extern void remove_phi_args (edge);
-extern void remove_phi_node (tree, tree);
+extern void remove_phi_node (tree, tree, bool);
 extern tree phi_reverse (tree);
 
 /* In gimple-low.c  */

gcc/tree-outof-ssa.c

@@ -639,7 +639,7 @@ eliminate_virtual_phis (void)
 		    }
 		}
 #endif
-	      remove_phi_node (phi, NULL_TREE);
+	      remove_phi_node (phi, NULL_TREE, true);
 	    }
 	}
     }
@@ -1170,13 +1170,13 @@ remove_ssa_form (bool perform_ter)
   if (values)
     free (values);
 
-  /* Remove phi nodes which have been translated back to real variables.  */
+  /* Remove PHI nodes which have been translated back to real variables.  */
   FOR_EACH_BB (bb)
     {
       for (phi = phi_nodes (bb); phi; phi = next)
 	{
 	  next = PHI_CHAIN (phi);
-	  remove_phi_node (phi, NULL_TREE);
+	  remove_phi_node (phi, NULL_TREE, true);
 	}
     }
 

gcc/tree-phinodes.c

@@ -233,6 +233,7 @@ make_phi_node (tree var, int len)
       imm->next = NULL;
       imm->stmt = phi;
     }
+
   return phi;
 }
 
@@ -301,7 +302,6 @@ resize_phi_node (tree *phi, int len)
       imm->stmt = new_phi;
     }
 
-
   *phi = new_phi;
 }
 
@@ -343,6 +343,7 @@ reserve_phi_args_for_new_edge (basic_block bb)
     }
 }
 
+
 /* Create a new PHI node for variable VAR at basic block BB.  */
 
 tree
@@ -362,6 +363,7 @@ create_phi_node (tree var, basic_block bb)
   return phi;
 }
 
+
 /* Add a new argument to PHI node PHI.  DEF is the incoming reaching
    definition and E is the edge through which DEF reaches PHI.  The new
    argument is added at the end of the argument list.
@@ -394,6 +396,7 @@ add_phi_arg (tree phi, tree def, edge e)
   SET_PHI_ARG_DEF (phi, e->dest_idx, def);
 }
 
+
 /* Remove the Ith argument from PHI's argument list.  This routine
    implements removal by swapping the last alternative with the
    alternative we want to delete and then shrinking the vector, which
@@ -406,7 +409,6 @@ remove_phi_arg_num (tree phi, int i)
 
   gcc_assert (i < num_elem);
 
-
   /* Delink the item which is being removed.  */
   delink_imm_use (&(PHI_ARG_IMM_USE_NODE (phi, i)));
 
@@ -428,6 +430,7 @@ remove_phi_arg_num (tree phi, int i)
   PHI_NUM_ARGS (phi)--;
 }
 
+
 /* Remove all PHI arguments associated with edge E.  */
 
 void
@@ -439,11 +442,14 @@ remove_phi_args (edge e)
     remove_phi_arg_num (phi, e->dest_idx);
 }
 
+
 /* Remove PHI node PHI from basic block BB.  If PREV is non-NULL, it is
-   used as the node immediately before PHI in the linked list.  */
+   used as the node immediately before PHI in the linked list.  If
+   RELEASE_LHS_P is true, the LHS of this PHI node is released into
+   the free pool of SSA names.  */
 
 void
-remove_phi_node (tree phi, tree prev)
+remove_phi_node (tree phi, tree prev, bool release_lhs_p)
 {
   tree *loc;
 
@@ -465,7 +471,8 @@ remove_phi_node (tree phi, tree prev)
   /* If we are deleting the PHI node, then we should release the
      SSA_NAME node so that it can be reused.  */
   release_phi_node (phi);
-  release_ssa_name (PHI_RESULT (phi));
+  if (release_lhs_p)
+    release_ssa_name (PHI_RESULT (phi));
 }
 
 

gcc/tree-scalar-evolution.c

@@ -2929,8 +2929,9 @@ scev_const_prop (void)
 	}
     }
 
-  /* Remove the ssa names that were replaced by constants.  We do not remove them
-     directly in the previous cycle, since this invalidates scev cache.  */
+  /* Remove the ssa names that were replaced by constants.  We do not
+     remove them directly in the previous cycle, since this
+     invalidates scev cache.  */
   if (ssa_names_to_remove)
     {
       bitmap_iterator bi;
@@ -2941,7 +2942,7 @@ scev_const_prop (void)
 	  phi = SSA_NAME_DEF_STMT (name);
 
 	  gcc_assert (TREE_CODE (phi) == PHI_NODE);
-	  remove_phi_node (phi, NULL);
+	  remove_phi_node (phi, NULL, true);
 	}
 
       BITMAP_FREE (ssa_names_to_remove);
@@ -2998,11 +2999,10 @@ scev_const_prop (void)
 	      || contains_abnormal_ssa_name_p (def))
 	    continue;
 
-	  /* Eliminate the phi node and replace it by a computation outside
+	  /* Eliminate the PHI node and replace it by a computation outside
 	     the loop.  */
 	  def = unshare_expr (def);
-	  SET_PHI_RESULT (phi, NULL_TREE);
-	  remove_phi_node (phi, NULL_TREE);
+	  remove_phi_node (phi, NULL_TREE, false);
 
 	  ass = build2 (GIMPLE_MODIFY_STMT, void_type_node, rslt, NULL_TREE);
 	  SSA_NAME_DEF_STMT (rslt) = ass;

gcc/tree-ssa-dom.c

@@ -2089,7 +2089,7 @@ static void
 remove_stmt_or_phi (tree t)
 {
   if (TREE_CODE (t) == PHI_NODE)
-    remove_phi_node (t, NULL);
+    remove_phi_node (t, NULL, true);
   else
     {
       block_stmt_iterator bsi = bsi_for_stmt (t);

gcc/tree-ssa-loop-ivopts.c

@@ -5351,12 +5351,7 @@ remove_statement (tree stmt, bool including_defined_name)
 {
   if (TREE_CODE (stmt) == PHI_NODE)
     {
-      if (!including_defined_name)
-	{
-	  /* Prevent the ssa name defined by the statement from being removed.  */
-	  SET_PHI_RESULT (stmt, NULL);
-	}
-      remove_phi_node (stmt, NULL_TREE);
+      remove_phi_node (stmt, NULL_TREE, including_defined_name);
     }
   else
     {

gcc/tree-ssa-pre.c

@@ -4035,7 +4035,7 @@ remove_dead_inserted_code (void)
 
 	  if (TREE_CODE (t) == PHI_NODE)
 	    {
-	      remove_phi_node (t, NULL);
+	      remove_phi_node (t, NULL, true);
 	    }
 	  else
 	    {