--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.max.asmdis/src/com/sun/max/asm/InstructionWithOffset.java	Sat Dec 17 19:59:18 2011 +0100
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2007, 2011, 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.max.asm;
+
+import com.sun.max.lang.*;
+
+/**
+ * An instruction that addresses some data as an offset from itself.
+ */
+public abstract class InstructionWithOffset extends InstructionWithLabel {
+
+    /**
+     * The mask of all the valid offset sizes supported by the union of all instructions that can address some data via an offset.
+     */
+    public static final int ALL_VALID_OFFSET_SIZES_MASK = WordWidth.BITS_8.numberOfBytes | WordWidth.BITS_16.numberOfBytes | WordWidth.BITS_32.numberOfBytes | WordWidth.BITS_64.numberOfBytes;
+
+    private final int validOffsetSizesMask;
+    private int offsetSize;
+
+    /**
+     * Creates an object representing an instruction that addresses some data as an offset from itself.
+     *
+     * @param startPosition the current position in the instruction stream of the instruction's first byte
+     * @param endPosition the current position in the instruction stream one byte past the instruction's last byte
+     * @param label a label representing the position referred to by this instruction
+     * @param validOffsetSizesMask a mask of the offset sizes supported by a concrete instruction. This value must not
+     *            be 0 and its set of non-zero bits must be a subset of the non-zero bits of
+     *            {@link #ALL_VALID_OFFSET_SIZES_MASK}. The one-bit integer values (i.e. the powers of two)
+     *            corresponding with each set bit in the mask are the offset sizes for which there is an available
+     *            concrete instruction. The concrete instruction emitted once the label has been bound is the one with
+     *            smallest offset size that can represent the distance between the label's position and this
+     *            instruction.
+     */
+    protected InstructionWithOffset(Assembler assembler, int startPosition, int endPosition, Label label, int validOffsetSizesMask) {
+        super(assembler, startPosition, endPosition, label);
+        this.validOffsetSizesMask = validOffsetSizesMask;
+        assert validOffsetSizesMask != 0;
+        assert (validOffsetSizesMask & ~ALL_VALID_OFFSET_SIZES_MASK) == 0;
+        if (Ints.isPowerOfTwoOrZero(validOffsetSizesMask)) {
+            assembler.addFixedSizeAssembledObject(this);
+            this.offsetSize = validOffsetSizesMask;
+        } else {
+            assembler.addSpanDependentInstruction(this);
+            this.offsetSize = Integer.lowestOneBit(validOffsetSizesMask);
+        }
+    }
+
+    protected InstructionWithOffset(Assembler assembler, int startPosition, int endPosition, Label label) {
+        super(assembler, startPosition, endPosition, label);
+        this.validOffsetSizesMask = 0;
+        assembler.addFixedSizeAssembledObject(this);
+    }
+
+    void setSize(int nBytes) {
+        variableSize = nBytes;
+    }
+
+    protected final int labelSize() {
+        return offsetSize;
+    }
+
+    /**
+     * Updates the size of this instruction's label based on the value bound to the label.
+     *
+     * @return true if the size of this instruction's label was changed
+     */
+    boolean updateLabelSize() throws AssemblyException {
+        if (validOffsetSizesMask == 0) {
+            return false;
+        }
+        int newOffsetSize = WordWidth.signedEffective(offset()).numberOfBytes;
+        if (newOffsetSize > this.offsetSize) {
+            final int maxLabelSize = Integer.highestOneBit(validOffsetSizesMask);
+            if (newOffsetSize > maxLabelSize) {
+                throw new AssemblyException("instruction cannot accomodate number of bits required for offset");
+            }
+            while ((newOffsetSize & validOffsetSizesMask) == 0) {
+                newOffsetSize = newOffsetSize << 1;
+            }
+            this.offsetSize = newOffsetSize;
+            return true;
+        }
+        return false;
+    }
+
+    private int offset() throws AssemblyException {
+        return assembler().offsetInstructionRelative(label(), this);
+    }
+
+    protected byte offsetAsByte() throws AssemblyException {
+        if (assembler().selectingLabelInstructions()) {
+            return (byte) 0;
+        }
+        final int result = offset();
+        if (Ints.numberOfEffectiveSignedBits(result) > 8) {
+            throw new AssemblyException("label out of 8-bit range");
+        }
+        return (byte) result;
+    }
+
+    protected short offsetAsShort() throws AssemblyException {
+        if (assembler().selectingLabelInstructions()) {
+            return (short) 0;
+        }
+        final int result = offset();
+        if (Ints.numberOfEffectiveSignedBits(result) > 16) {
+            throw new AssemblyException("label out of 16-bit range");
+        }
+        return (short) result;
+    }
+
+    protected int offsetAsInt() throws AssemblyException {
+        if (assembler().selectingLabelInstructions()) {
+            return 0;
+        }
+        return offset();
+    }
+
+}