--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.max.cri/src/com/oracle/max/cri/ci/CiStackSlot.java	Tue Jan 03 16:29:28 2012 +0100
@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) 2010, 2012, 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.oracle.max.cri.ci;
+
+import static com.oracle.max.cri.ci.CiKind.*;
+
+/**
+ * Represents a compiler spill slot or an outgoing stack-based argument in a method's frame
+ * or an incoming stack-based argument in a method's {@linkplain #inCallerFrame() caller's frame}.
+ */
+public final class CiStackSlot extends CiValue {
+    private static final long serialVersionUID = -7725071921307318433L;
+
+    private final int offset;
+    private final boolean addFrameSize;
+
+    /**
+     * Gets a {@link CiStackSlot} instance representing a stack slot at a given index
+     * holding a value of a given kind.
+     *
+     * @param kind The kind of the value stored in the stack slot.
+     * @param offset The offset of the stack slot (in bytes)
+     * @param inCallerFrame Specifies if the offset is relative to the stack pointer,
+     *        or the beginning of the frame (stack pointer + total frame size).
+     */
+    public static CiStackSlot get(CiKind kind, int offset, boolean addFrameSize) {
+        assert kind.stackKind() == kind;
+        assert addFrameSize || offset >= 0;
+
+        if (offset % CACHE_GRANULARITY == 0) {
+            CiStackSlot[][] cache;
+            int index = offset / CACHE_GRANULARITY;
+            if (!addFrameSize) {
+                cache = OUT_CACHE;
+            } else if (offset >= 0) {
+                cache = IN_CACHE;
+            } else {
+                cache = SPILL_CACHE;
+                index = -index;
+            }
+            CiStackSlot[] slots = cache[kind.ordinal()];
+            if (index < slots.length) {
+                CiStackSlot slot = slots[index];
+                assert slot.kind == kind && slot.offset == offset && slot.addFrameSize == addFrameSize;
+                return slot;
+            }
+        }
+        return new CiStackSlot(kind, offset, addFrameSize);
+    }
+
+    /**
+     * Private constructor to enforce use of {@link #get()} so that a cache can be used.
+     */
+    private CiStackSlot(CiKind kind, int offset, boolean addFrameSize) {
+        super(kind);
+        this.offset = offset;
+        this.addFrameSize = addFrameSize;
+    }
+
+    /**
+     * Gets the offset of this stack slot, relative to the stack pointer.
+     * @return The offset of this slot (in bytes).
+     */
+    public int offset(int totalFrameSize) {
+        assert totalFrameSize > 0 || !addFrameSize;
+        int result = offset + (addFrameSize ? totalFrameSize : 0);
+        assert result >= 0;
+        return result;
+    }
+
+    public boolean inCallerFrame() {
+        return addFrameSize && offset >= 0;
+    }
+
+    public int rawOffset() {
+        return offset;
+    }
+
+    public boolean rawAddFrameSize() {
+        return addFrameSize;
+    }
+
+    @Override
+    public int hashCode() {
+        return kind.ordinal() ^ (offset << 4) ^ (addFrameSize ? 15 : 0);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (o == this) {
+            return true;
+        }
+        if (o instanceof CiStackSlot) {
+            CiStackSlot l = (CiStackSlot) o;
+            return l.kind == kind && l.offset == offset && l.addFrameSize == addFrameSize;
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        String s;
+        if (!addFrameSize) {
+            s = "out:";
+        } else if (offset >= 0) {
+            s = "in:";
+        } else {
+            s = "spill:";
+        }
+        return s + offset + kindSuffix();
+    }
+
+    /**
+     * Gets this stack slot used to pass an argument from the perspective of a caller.
+     */
+    public CiStackSlot asOutArg() {
+        assert offset >= 0;
+        if (addFrameSize) {
+            return get(kind, offset, false);
+        }
+        return this;
+    }
+
+    /**
+     * Gets this stack slot used to pass an argument from the perspective of a callee.
+     */
+    public CiStackSlot asInArg() {
+        assert offset >= 0;
+        if (!addFrameSize) {
+            return get(kind, offset, true);
+        }
+        return this;
+    }
+
+
+    private static final int CACHE_GRANULARITY = 8;
+    private static final int SPILL_CACHE_PER_KIND_SIZE = 100;
+    private static final int PARAM_CACHE_PER_KIND_SIZE = 10;
+
+    private static final CiStackSlot[][] SPILL_CACHE = makeCache(SPILL_CACHE_PER_KIND_SIZE, -1, true);
+    private static final CiStackSlot[][] IN_CACHE = makeCache(PARAM_CACHE_PER_KIND_SIZE, 1, true);
+    private static final CiStackSlot[][] OUT_CACHE = makeCache(PARAM_CACHE_PER_KIND_SIZE, 1, false);
+
+    private static CiStackSlot[][] makeCache(int cachePerKindSize, int sign, boolean addFrameSize) {
+        CiStackSlot[][] cache = new CiStackSlot[CiKind.VALUES.length][];
+        for (CiKind kind : new CiKind[] {Illegal, Int, Long, Float, Double, Object, Jsr}) {
+            CiStackSlot[] slots = new CiStackSlot[cachePerKindSize];
+            for (int i = 0; i < cachePerKindSize; i++) {
+                slots[i] = new CiStackSlot(kind, sign * i * CACHE_GRANULARITY, addFrameSize);
+            }
+            cache[kind.ordinal()] = slots;
+        }
+        return cache;
+    }
+}