--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/GraalCompiler/src/com/sun/c1x/util/BlockWorkList.java	Wed Apr 27 11:50:44 2011 +0200
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2009, 2009, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.sun.c1x.util;
+
+import com.sun.c1x.ir.*;
+
+/**
+ * This class implements a worklist for dealing with blocks. The worklist can
+ * operate either as a stack (i.e. first-in / last-out), or as a sorted list,
+ * where blocks can be sorted by a supplied number. The latter usage lends itself
+ * naturally to iterative dataflow analysis problems.
+ *
+ * This implementation is not able to tell if a block is in the worklist already.
+ * Note that this implementation is slightly less efficient than the dedicated
+ * work list in {@link com.sun.c1x.graph.ScopeData}, because this worklist uses
+ * an externally supplied number.
+ *
+ * @author Ben L. Titzer
+ */
+public class BlockWorkList {
+    BlockBegin[] workList;
+    int[] workListNumbers;
+    int workListIndex;
+
+    /**
+     * Adds a block to this list in an unsorted fashion, like a stack.
+     * @param block the block to add
+     */
+    public void add(BlockBegin block) {
+        if (workList == null) {
+            // worklist not allocated yet
+            allocate();
+        } else if (workListIndex == workList.length) {
+            // need to grow the worklist
+            grow();
+        }
+        // put the block at the end of the array
+        workList[workListIndex++] = block;
+    }
+
+    /**
+     * Adds a block to this list, sorted by the supplied number. The block
+     * with the lowest number is returned upon subsequent removes.
+     * @param block the block to add
+     * @param number the number used to sort the block
+     */
+    public void addSorted(BlockBegin block, int number) {
+        if (workList == null) {
+            // worklist not allocated yet
+            allocate();
+        } else if (workListIndex == workList.length) {
+            // need to grow the worklist
+            grow();
+        }
+        // put the block at the end of the array
+        workList[workListIndex] = block;
+        workListNumbers[workListIndex] = number;
+        workListIndex++;
+        int i = workListIndex - 2;
+        // push block towards the beginning of the array
+        for (; i >= 0; i--) {
+            int n = workListNumbers[i];
+            if (n >= number) {
+                break; // already in the right position
+            }
+            workList[i + 1] = workList[i]; // bubble b down by one
+            workList[i] = block;           // and overwrite its place with block
+            workListNumbers[i + 1] = n;    // bubble n down by one
+            workListNumbers[i] = number;   // and overwrite its place with number
+        }
+    }
+
+    /**
+     * Removes the next block from this work list. If the blocks have been added
+     * in a sorted order, then the block with the lowest number is returned. Otherwise,
+     * the last block added is returned.
+     * @return the next block in the list
+     */
+    public BlockBegin removeFromWorkList() {
+        if (workListIndex != 0) {
+            return workList[--workListIndex];
+        }
+        return null;
+    }
+
+    /**
+     * Checks whether the list is empty.
+     * @return {@code true} if this list is empty
+     */
+    public boolean isEmpty() {
+        return workListIndex == 0;
+    }
+
+    private void allocate() {
+        workList = new BlockBegin[5];
+        workListNumbers = new int[5];
+    }
+
+    private void grow() {
+        int prevLength = workList.length;
+        BlockBegin[] nworkList = new BlockBegin[prevLength * 3];
+        System.arraycopy(workList, 0, nworkList, 0, prevLength);
+        workList = nworkList;
+
+        int[] nworkListNumbers = new int[prevLength * 3];
+        System.arraycopy(workListNumbers, 0, nworkListNumbers, 0, prevLength);
+        workListNumbers = nworkListNumbers;
+    }
+}