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19
20 package jode.flow;
21 import jode.decompiler.LocalInfo;
22 import jode.expr.Expression;
23 import jode.expr.LocalLoadOperator;
24 import jode.expr.Operator;
25
26
35 public class VariableStack {
36 public final static VariableStack EMPTY = new VariableStack();
37
38 final LocalInfo[] stackMap;
39
40 private VariableStack() {
41 stackMap = new LocalInfo[0];
42 }
43
44 private VariableStack(LocalInfo[] stack) {
45 stackMap = stack;
46 }
47
48 public boolean isEmpty() {
49 return stackMap.length == 0;
50 }
51
52 public VariableStack pop(int count) {
53 LocalInfo[] newStack = new LocalInfo[stackMap.length - count];
54 System.arraycopy(stackMap, 0, newStack, 0, stackMap.length - count);
55 return new VariableStack(newStack);
56 }
57
58 public VariableStack push(LocalInfo li) {
59 return poppush(0, li);
60 }
61
62 public VariableStack poppush(int count, LocalInfo li) {
63 LocalInfo[] newStack = new LocalInfo[stackMap.length - count + 1];
64 System.arraycopy(stackMap, 0, newStack, 0, stackMap.length - count);
65 newStack[stackMap.length - count] = li;
66 return new VariableStack(newStack);
67 }
68
69 public VariableStack peek(int count) {
70 LocalInfo[] peeked = new LocalInfo[count];
71 System.arraycopy(stackMap, stackMap.length - count, peeked, 0, count);
72 return new VariableStack(peeked);
73 }
74
75 public void merge(VariableStack other) {
76 if (stackMap.length != other.stackMap.length)
77 throw new IllegalArgumentException  ("stack length differs");
78 for (int i=0; i<stackMap.length; i++) {
79 if (stackMap[i].getType().stackSize()
80 != other.stackMap[i].getType().stackSize())
81 throw new IllegalArgumentException
82 ("stack element length differs at "+i);
83 stackMap[i].combineWith(other.stackMap[i]);
84 }
85 }
86
87
91 public static VariableStack merge(VariableStack first,
92 VariableStack second) {
93 if (first == null)
94 return second;
95 else if (second == null)
96 return first;
97 first.merge(second);
98 return first;
99 }
100
101 public Expression mergeIntoExpression(Expression expr) {
102
103
104 for (int i = stackMap.length-1; i >= 0; i--) {
105 expr = expr.addOperand
108 (new LocalLoadOperator(stackMap[i].getType(), null,
109 stackMap[i]));
110 }
111 return expr;
112 }
113
114 public VariableStack executeSpecial(SpecialBlock special) {
115 if (special.type == special.POP) {
116 int popped = 0;
117 int newLength = stackMap.length;
118 while (popped < special.count) {
119 newLength--;
120 popped += stackMap[newLength].getType().stackSize();
121 }
122 if (popped != special.count)
123 throw new IllegalArgumentException ("wrong POP");
124 LocalInfo[] newStack = new LocalInfo[newLength];
125 System.arraycopy(stackMap, 0, newStack, 0, newLength);
126 return new VariableStack(newStack);
127 } else if (special.type == special.DUP) {
128 int popped = 0;
129 int numDup = 0;
130 int startDup = stackMap.length;
131 while (popped < special.count) {
132 startDup--;
133 numDup++;
134 popped += stackMap[startDup].getType().stackSize();
135 }
136 if (popped != special.count)
137 throw new IllegalArgumentException ("wrong DUP");
138 int destDup = startDup;
139 int depth = 0;
140 while (depth < special.depth) {
141 destDup--;
142 depth += stackMap[destDup].getType().stackSize();
143 }
144 if (depth != special.depth)
145 throw new IllegalArgumentException ("wrong DUP");
146 LocalInfo[] newStack = new LocalInfo[stackMap.length + numDup];
147 System.arraycopy(stackMap, 0, newStack, 0, destDup);
148 System.arraycopy(stackMap, startDup, newStack, destDup, numDup);
149 System.arraycopy(stackMap, destDup, newStack, destDup + numDup,
150 startDup - destDup);
151 System.arraycopy(stackMap, startDup, newStack, startDup + numDup,
152 numDup);
153 return new VariableStack(newStack);
154 } else if (special.type == special.SWAP) {
155 LocalInfo[] newStack = new LocalInfo[stackMap.length];
156 System.arraycopy(stackMap, 0, newStack, 0, stackMap.length - 2);
157 if (stackMap[stackMap.length-2].getType().stackSize() != 1
158 || stackMap[stackMap.length-1].getType().stackSize() != 1)
159 throw new IllegalArgumentException ("wrong SWAP");
160 newStack[stackMap.length-2] = stackMap[stackMap.length-1];
161 newStack[stackMap.length-1] = stackMap[stackMap.length-2];
162 return new VariableStack(newStack);
163 } else
164 throw new jode.AssertError("Unknown SpecialBlock");
165 }
166
167 public String toString() {
168 StringBuffer result = new StringBuffer ("[");
169 for (int i=0; i < stackMap.length; i++) {
170 if (i>0)
171 result.append(", ");
172 result.append(stackMap[i].getName());
173 }
174 return result.append("]").toString();
175 }
176 }
177 |
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