From 87fdf7fff070b1fb0ed2dea21cfee8c5aa42429d Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@cygnus.com>
Date: Tue, 21 Sep 1999 18:54:34 +0000
Subject: [PATCH] flow.c (remove_edge): New function to remove an edge from the
 flow graph.

Tue Sep 21 14:51:23 EDT 1999  Andrew MacLeod  <amacleod@cygnus.com>

	* flow.c (remove_edge): New function to remove an edge from the
	flow graph.
	(remove_fake_successors): New function to remove fake successor edges.
	(remove_fake_edges): New function to remove all fake edges from the
	flow graph.
	(add_fake_exit_edges): New function to add fake edges from all blocks
	with no successors to the exit block.
	* basic-block.h (remove_fake_edges, add_fake_exit_edges): Add
	prototypes for new functions.

From-SVN: r29555
---
 gcc/ChangeLog     | 12 +++++++
 gcc/basic-block.h |  2 ++
 gcc/flow.c        | 84 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 98 insertions(+)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b3f6bcdf0d8..2dc37e85446 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,15 @@
+Tue Sep 21 14:51:23 EDT 1999  Andrew MacLeod  <amacleod@cygnus.com>
+
+	* flow.c (remove_edge): New function to remove an edge from the 
+	flow graph.
+	(remove_fake_successors): New function to remove fake successor edges.
+	(remove_fake_edges): New function to remove all fake edges from the
+	flow graph.
+	(add_fake_exit_edges): New function to add fake edges from all blocks
+	with no successors to the exit block.
+	* basic-block.h (remove_fake_edges, add_fake_exit_edges): Add 
+	prototypes for new functions.
+
 Tue Sep 21 14:49:53 EDT 1999  Andrew MacLeod  <amacleod@cygnus.com>
 
 	* config/mips/elf64.h (ASM_OUTPUT_CONSTRUCTOR, ASM_OUTPUT_DESTRUCTOR):
diff --git a/gcc/basic-block.h b/gcc/basic-block.h
index 06ef7cf452c..26b509cccf7 100644
--- a/gcc/basic-block.h
+++ b/gcc/basic-block.h
@@ -244,6 +244,8 @@ extern void free_basic_block_vars	PROTO ((int));
 extern basic_block split_edge		PROTO ((edge));
 extern void insert_insn_on_edge		PROTO ((rtx, edge));
 extern void commit_edge_insertions	PROTO ((void));
+extern void remove_fake_edges		PROTO ((void));
+extern void add_fake_exit_edges		PROTO ((void));
 
 /* This structure maintains an edge list vector.  */
 struct edge_list 
diff --git a/gcc/flow.c b/gcc/flow.c
index 95743d882eb..d47612b5d6b 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -6751,3 +6751,87 @@ find_edge_index (edge_list, pred, succ)
   return (EDGE_INDEX_NO_EDGE);
 }
 
+/* This function will remove an edge from the flow graph.  */
+static void
+remove_edge (e)
+     edge e;
+{
+  edge last_pred = NULL;
+  edge last_succ = NULL;
+  edge tmp;
+  basic_block src, dest;
+  src = e->src;
+  dest = e->dest;
+  for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
+    last_succ = tmp;
+
+  if (!tmp)
+    abort ();
+  if (last_succ)
+    last_succ->succ_next = e->succ_next;
+  else
+    src->succ = e->succ_next;
+
+  for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
+    last_pred = tmp;
+
+  if (!tmp)
+    abort ();
+  if (last_pred)
+    last_pred->pred_next = e->pred_next;
+  else
+    dest->pred = e->pred_next;
+
+  free (e);
+
+}
+
+/* This routine will remove any fake successor edges for a basic block.
+   When the edge is removed, it is also removed from whatever predecessor
+   list it is in.  */
+static void
+remove_fake_successors (bb)
+     basic_block bb;
+{
+  edge e;
+  for (e = bb->succ; e ; )
+    {
+      edge tmp = e;
+      e = e->succ_next;
+      if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
+	remove_edge (tmp);
+    }
+}
+
+/* This routine will remove all fake edges from the flow graph.  If
+   we remove all fake successors, it will automatically remove all
+   fake predecessors.  */
+void
+remove_fake_edges ()
+{
+  int x;
+  edge e;
+  basic_block bb;
+
+  for (x = 0; x < n_basic_blocks; x++)
+    {
+      edge tmp, last = NULL;
+      bb = BASIC_BLOCK (x);
+      remove_fake_successors (bb);
+    }
+  /* we've handled all successors except the entry block's.  */
+  remove_fake_successors (ENTRY_BLOCK_PTR);
+}
+
+/* This functions will add a fake edge between any block which has no
+   successors, and the exit block. Some data flow equations require these
+   edges to exist.  */
+void
+add_fake_exit_edges ()
+{
+  int x;
+
+  for (x = 0; x < n_basic_blocks; x++)
+    if (BASIC_BLOCK (x)->succ == NULL)
+      make_edge (BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
+}