--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jvmci/com.oracle.jvmci.code/src/com/oracle/jvmci/code/RegisterSaveLayout.java	Tue Jun 09 00:22:49 2015 +0200
@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2013, 2014, 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.jvmci.code;
+
+import java.util.*;
+
+/**
+ * A map from registers to frame slots. This can be used to describe where callee saved registers
+ * are saved in a callee's frame.
+ */
+public final class RegisterSaveLayout {
+
+    /**
+     * Keys.
+     */
+    private final Register[] registers;
+
+    /**
+     * Slot indexes relative to stack pointer.
+     */
+    private final int[] slots;
+
+    /**
+     * Creates a map from registers to frame slots.
+     *
+     * @param registers the keys in the map
+     * @param slots frame slot index for each register in {@code registers}
+     */
+    public RegisterSaveLayout(Register[] registers, int[] slots) {
+        assert registers.length == slots.length;
+        this.registers = registers;
+        this.slots = slots;
+        assert registersToSlots(false).size() == registers.length : "non-unique registers";
+        assert new HashSet<>(registersToSlots(false).values()).size() == slots.length : "non-unqiue slots";
+    }
+
+    /**
+     * Gets the frame slot index for a given register.
+     *
+     * @param register register to get the frame slot index for
+     * @return frame slot index
+     */
+    public int registerToSlot(Register register) {
+        for (int i = 0; i < registers.length; i++) {
+            if (register.equals(registers[i])) {
+                return slots[i];
+            }
+        }
+        throw new IllegalArgumentException(register + " not saved by this layout: " + this);
+    }
+
+    /**
+     * Gets this layout information as a {@link Map} from registers to slots.
+     */
+    public Map<Register, Integer> registersToSlots(boolean sorted) {
+        Map<Register, Integer> result;
+        if (sorted) {
+            result = new TreeMap<>();
+        } else {
+            result = new HashMap<>();
+        }
+        for (int i = 0; i < registers.length; i++) {
+            result.put(registers[i], slots[i]);
+        }
+        return result;
+    }
+
+    /**
+     * Gets this layout information as a {@link Map} from slots to registers.
+     */
+    public Map<Integer, Register> slotsToRegisters(boolean sorted) {
+        Map<Integer, Register> result;
+        if (sorted) {
+            result = new TreeMap<>();
+        } else {
+            result = new HashMap<>();
+        }
+        for (int i = 0; i < registers.length; i++) {
+            result.put(slots[i], registers[i]);
+        }
+        return result;
+    }
+
+    @Override
+    public int hashCode() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof RegisterSaveLayout) {
+            RegisterSaveLayout that = (RegisterSaveLayout) obj;
+            if (Arrays.equals(registers, that.registers) && Arrays.equals(slots, that.slots)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return registersToSlots(true).toString();
+    }
+}