Mercurial > hg > graal-jvmci-8
view graal/com.oracle.max.asmdis/src/com/sun/max/asm/AlignmentPadding.java @ 4222:8e2985cdaaa5
Renaming of VMExits and VMEntries part 3.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Wed, 04 Jan 2012 21:13:44 +0100 |
parents | e233f5660da4 |
children |
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/* * 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; /** * Byte stream padding for memory alignment in the assembler. This pseudo-instruction pads the byte stream to ensure that the next * memory location is aligned on the specified boundary. * Padding may also be performed conditionally to the amount of space left in the byte stream before the next aligned boundary. */ public abstract class AlignmentPadding extends MutableAssembledObject { public AlignmentPadding(Assembler assembler, int startPosition, int endPosition, int alignment, int alignmentStart, int requiredSpace, byte padByte) { super(assembler, startPosition, endPosition); this.alignment = alignment; this.padByte = padByte; this.alignmentStart = alignmentStart; this.maxMisalignment = alignment - requiredSpace; assembler.addAlignmentPadding(this); } private final int alignment; public final int alignment() { return alignment; } /** * Max misalignment supported. If greater than that, pad to the next alignment. * By default, this is zero, meaning that padding is always performed to the next alignment. * When we want to pad only if there isn't enough space to fit the next object of size s, maxMisalignment is * set to alignment - s. */ private final int maxMisalignment; private final int alignmentStart; private final byte padByte; public void updatePadding() { // We avoid sign problems with '%' below by masking off the sign bit: final long unsignedAddend = (assembler().baseAddress() + startPosition()) & 0x7fffffffffffffffL; final int misalignmentSize = (int) (unsignedAddend % alignment); variableSize = (misalignmentSize <= maxMisalignment) ? 0 : alignment - misalignmentSize; } @Override protected void assemble() throws AssemblyException { for (int i = alignmentStart; i < size(); i++) { assembler().emitByte(padByte); } } }