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| 1 | /* | ||
| 2 | * Copyright (c) 1995, 2003, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package sun.tools.asm; | ||
| 27 | |||
| 28 | import sun.tools.java.*; | ||
| 29 | import java.io.IOException; | ||
| 30 | import java.io.DataOutputStream; | ||
| 31 | |||
| 32 | /** | ||
| 33 | * This class is used to assemble the local variable table. | ||
| 34 | * | ||
| 35 | * WARNING: The contents of this source file are not part of any | ||
| 36 | * supported API. Code that depends on them does so at its own risk: | ||
| 37 | * they are subject to change or removal without notice. | ||
| 38 | * | ||
| 39 | * @author Arthur van Hoff | ||
| 40 | */ | ||
| 41 | final | ||
| 42 | class LocalVariableTable { | ||
| 43 | LocalVariable locals[] = new LocalVariable[8]; | ||
| 44 | int len; | ||
| 45 | |||
| 46 | /** | ||
| 47 | * Define a new local variable. Merge entries where possible. | ||
| 48 | */ | ||
| 49 | void define(MemberDefinition field, int slot, int from, int to) { | ||
| 50 | if (from >= to) { | ||
| 51 | return; | ||
| 52 | } | ||
| 53 | for (int i = 0 ; i < len ; i++) { | ||
| 54 | if ((locals[i].field == field) && (locals[i].slot == slot) && | ||
| 55 | (from <= locals[i].to) && (to >= locals[i].from)) { | ||
| 56 | locals[i].from = Math.min(locals[i].from, from); | ||
| 57 | locals[i].to = Math.max(locals[i].to, to); | ||
| 58 | return; | ||
| 59 | } | ||
| 60 | } | ||
| 61 | if (len == locals.length) { | ||
| 62 | LocalVariable newlocals[] = new LocalVariable[len * 2]; | ||
| 63 | System.arraycopy(locals, 0, newlocals, 0, len); | ||
| 64 | locals = newlocals; | ||
| 65 | } | ||
| 66 | locals[len++] = new LocalVariable(field, slot, from, to); | ||
| 67 | } | ||
| 68 | |||
| 69 | /** | ||
| 70 | * Trim overlapping local ranges. Java forbids shadowing of | ||
| 71 | * locals in nested scopes, but non-nested scopes may still declare | ||
| 72 | * locals with the same name. Because local variable ranges are | ||
| 73 | * computed using flow analysis as part of assembly, it isn't | ||
| 74 | * possible to simply make sure variable ranges end where the | ||
| 75 | * enclosing lexical scope ends. This method makes sure that | ||
| 76 | * variables with the same name don't overlap, giving priority to | ||
| 77 | * fields with higher slot numbers that should have appeared later | ||
| 78 | * in the source. | ||
| 79 | */ | ||
| 80 | private void trim_ranges() { | ||
| 81 | for (int i=0; i<len; i++) { | ||
| 82 | for (int j=i+1; j<len; j++) { | ||
| 83 | if ((locals[i].field.getName()==locals[j].field.getName()) | ||
| 84 | && (locals[i].from <= locals[j].to) | ||
| 85 | && (locals[i].to >= locals[j].from)) { | ||
| 86 | // At this point we know that both ranges are | ||
| 87 | // the same name and there is also overlap or they abut | ||
| 88 | if (locals[i].slot < locals[j].slot) { | ||
| 89 | if (locals[i].from < locals[j].from) { | ||
| 90 | locals[i].to = Math.min(locals[i].to, locals[j].from); | ||
| 91 | } else { | ||
| 92 | // We've detected two local variables with the | ||
| 93 | // same name, and the one with the greater slot | ||
| 94 | // number starts before the other. This order | ||
| 95 | // reversal may happen with locals with the same | ||
| 96 | // name declared in both a try body and an | ||
| 97 | // associated catch clause. This is rare, and | ||
| 98 | // we give up. | ||
| 99 | } | ||
| 100 | } else if (locals[i].slot > locals[j].slot) { | ||
| 101 | if (locals[i].from > locals[j].from) { | ||
| 102 | locals[j].to = Math.min(locals[j].to, locals[i].from); | ||
| 103 | } else { | ||
| 104 | // Same situation as above; just give up. | ||
| 105 | } | ||
| 106 | } else { | ||
| 107 | // This case can happen if there are two variables | ||
| 108 | // with the same name and slot numbers, and ranges | ||
| 109 | // that abut. AFAIK the only way this can occur | ||
| 110 | // is with multiple static initializers. Punt. | ||
| 111 | } | ||
| 112 | } | ||
| 113 | } | ||
| 114 | } | ||
| 115 | } | ||
| 116 | |||
| 117 | /** | ||
| 118 | * Write out the data. | ||
| 119 | */ | ||
| 120 | void write(Environment env, DataOutputStream out, ConstantPool tab) throws IOException { | ||
| 121 | trim_ranges(); | ||
| 122 | out.writeShort(len); | ||
| 123 | for (int i = 0 ; i < len ; i++) { | ||
| 124 | //System.out.println("pc=" + locals[i].from + ", len=" + (locals[i].to - locals[i].from) + ", nm=" + locals[i].field.getName() + ", slot=" + locals[i].slot); | ||
| 125 | out.writeShort(locals[i].from); | ||
| 126 | out.writeShort(locals[i].to - locals[i].from); | ||
| 127 | out.writeShort(tab.index(locals[i].field.getName().toString())); | ||
| 128 | out.writeShort(tab.index(locals[i].field.getType().getTypeSignature())); | ||
| 129 | out.writeShort(locals[i].slot); | ||
| 130 | } | ||
| 131 | } | ||
| 132 | } | ||