Mercurial > hg > truffle
diff graal/com.oracle.max.asmdis/src/com/sun/max/asm/AlignmentPadding.java @ 3733:e233f5660da4
Added Java files from Maxine project.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Sat, 17 Dec 2011 19:59:18 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/com.oracle.max.asmdis/src/com/sun/max/asm/AlignmentPadding.java Sat Dec 17 19:59:18 2011 +0100 @@ -0,0 +1,72 @@ +/* + * 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); + } + } +}