[patch] tree-cfg.c (tree_block_forwards_to): Remove.

[Kazu Hirata <kazu at cs dot umass dot edu>]

Hi,

Attached is a patch to remove tree_block_forwards_to as it is unused.

thread_jumps now has a much faster implementation of following
forwarder blocks.  If somebody needs follow forwarder blocks, I am
happy to factor that out of thread_jumps.  (In fact, I might do so
without a request from somebody. :-)

Plus, bb_ann (bb)->forwardable is not maintained anywhere outside of
thread_jumps (and its children), so it is dangerous to externify
tree_block_forwards_to because it assumes that
bb_ann (bb)->forwardable is correctly maintained.

Bootstrapped on i686-pc-linux-gnu.  OK to apply?

Kazu Hirata

2004-10-07  Kazu Hirata  <kazu@cs.umass.edu>

	* tree-cfg.c (tree_block_forwards_to): Remove.
	* tree-flow.h: Remove the corresponding prototype.

Index: tree-cfg.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-cfg.c,v
retrieving revision 2.70
diff -u -r2.70 tree-cfg.c
--- tree-cfg.c	6 Oct 2004 19:05:12 -0000	2.70
+++ tree-cfg.c	7 Oct 2004 14:43:06 -0000
@@ -1843,69 +1843,6 @@
   remove_phi_nodes_and_edges_for_unreachable_block (bb);
 }
 
-
-/* Examine BB to determine if it is a forwarding block (a block which only
-   transfers control to a new destination).  If BB is a forwarding block,
-   then return the edge leading to the ultimate destination.  */
-
-edge
-tree_block_forwards_to (basic_block bb)
-{
-  block_stmt_iterator bsi;
-  bb_ann_t ann = bb_ann (bb);
-  tree stmt;
-
-  /* If this block is not forwardable, then avoid useless work.  */
-  if (! ann->forwardable)
-    return NULL;
-
-  /* Set this block to not be forwardable.  This prevents infinite loops since
-     any block currently under examination is considered non-forwardable.  */
-  ann->forwardable = 0;
-
-  /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
-     this block has more than one successor, this block's single successor is
-     reached via an abnormal edge, this block has phi nodes, or this block's
-     single successor has phi nodes.  */
-  if (bb == EXIT_BLOCK_PTR
-      || bb == ENTRY_BLOCK_PTR
-      || EDGE_COUNT (bb->succs) != 1
-      || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
-      || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) != 0
-      || phi_nodes (bb)
-      || phi_nodes (EDGE_SUCC (bb, 0)->dest))
-    return NULL;
-
-  /* Walk past any labels at the start of this block.  */
-  for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
-    {
-      stmt = bsi_stmt (bsi);
-      if (TREE_CODE (stmt) != LABEL_EXPR)
-	break;
-    }
-
-  /* If we reached the end of this block we may be able to optimize this
-     case.  */
-  if (bsi_end_p (bsi))
-    {
-      edge dest;
-
-      /* Recursive call to pick up chains of forwarding blocks.  */
-      dest = tree_block_forwards_to (EDGE_SUCC (bb, 0)->dest);
-
-      /* If none found, we forward to bb->succs[0] at minimum.  */
-      if (!dest)
-	dest = EDGE_SUCC (bb, 0);
-
-      ann->forwardable = 1;
-      return dest;
-    }
-
-  /* No forwarding possible.  */
-  return NULL;
-}
-
-
 /* Try to remove superfluous control structures.  */
 
 static bool
Index: tree-flow.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-flow.h,v
retrieving revision 2.51
diff -u -r2.51 tree-flow.h
--- tree-flow.h	6 Oct 2004 19:40:54 -0000	2.51
+++ tree-flow.h	7 Oct 2004 14:43:07 -0000
@@ -482,7 +482,6 @@
 extern edge thread_edge (edge, basic_block);
 extern basic_block label_to_block (tree);
 extern void tree_optimize_tail_calls (bool, enum tree_dump_index);
-extern edge tree_block_forwards_to (basic_block bb);
 extern void bsi_insert_on_edge (edge, tree);
 extern basic_block bsi_insert_on_edge_immediate (edge, tree);
 extern void bsi_commit_edge_inserts (int *);