Showing the changes to java/pkg/sun/tools/asm/LocalVariableTable.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,132 @@ | ||
| 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 | +} | |