001 /*
002 * This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 * This file is licensed to You under the Eclipse Public License (EPL);
005 * You may not use this file except in compliance with the License. You
006 * may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 * See the COPYRIGHT.txt file distributed with this work for information
011 * regarding copyright ownership.
012 */
013 package org.jikesrvm.compilers.opt.ir.operand;
014
015 import org.jikesrvm.compilers.opt.OptimizingCompilerException;
016
017 /**
018 * Represents a symbolic name for a stack location.
019 * <p>
020 * The stack location is defined by an offset from either the framepointer
021 * (top of stack frame) or stackpointer-home-location (bottom of frame).
022 */
023 public final class StackLocationOperand extends Operand {
024 /**
025 * Is the offset from the top or bottom of stack frame?
026 */
027 private boolean fromTop;
028
029 /**
030 * The offset (top/bottom of stack frame) corresponding
031 * to this stack location.
032 */
033 private int offset;
034
035 /**
036 * Size (in bytes) reserved for the value of this operand.
037 */
038 private byte size;
039
040 /**
041 * @param fromTop is the offset from the top of bottom of the frame?
042 * @param offset the offset of the stack location from the top/bottom
043 * of the frame
044 * @param size Size (in bytes) of the stack location.
045 */
046 public StackLocationOperand(boolean fromTop, int offset, byte size) {
047 this.fromTop = fromTop;
048 this.offset = offset;
049 this.size = size;
050 }
051
052 /**
053 * @param fromTop is the offset from the top of bottom of the frame?
054 * @param offset the offset of the stack location from the top/bottom
055 * of the frame
056 * @param size Size (in bytes) of the stack location.
057 */
058 public StackLocationOperand(boolean fromTop, int offset, int size) {
059 this.fromTop = fromTop;
060 this.offset = offset;
061 this.size = (byte) size;
062 }
063
064 /**
065 * @return <code>true</code> if the stack location uses the top of the
066 * frame as its base, <code>false</code> if it uses the bottom
067 * of the frame as its base.
068 */
069 public boolean isFromTop() {
070 return fromTop;
071 }
072
073 /**
074 * @return the offset from the frame pointer (top of stack frame)
075 * corresponding to this stack location.
076 */
077 public int getOffset() {
078 return offset;
079 }
080
081 /**
082 * @return Size (in bytes) of this stack location.
083 */
084 public byte getSize() {
085 return size;
086 }
087
088 @Override
089 public String toString() {
090 String s = "";
091 switch (size) {
092 case 1:
093 s = ">B";
094 break;
095 case 2:
096 s = ">W";
097 break;
098 case 4:
099 s = ">DW";
100 break;
101 case 8:
102 s = ">QW";
103 break;
104 default:
105 OptimizingCompilerException.UNREACHABLE();
106 }
107 return "<" + (isFromTop() ? "FrameTop" : "FrameBottom") + (getOffset() < 0 ? "" : "+") + getOffset() + s;
108 }
109
110 @Override
111 public boolean similar(Operand op) {
112 if (op instanceof StackLocationOperand) {
113 StackLocationOperand o2 = (StackLocationOperand) op;
114 return ((o2.isFromTop() == isFromTop()) && (o2.getOffset() == getOffset()) && (o2.getSize() == getSize()));
115 } else {
116 return false;
117 }
118 }
119
120 @Override
121 public Operand copy() {
122 return new StackLocationOperand(isFromTop(), getOffset(), getSize());
123 }
124 }