| /* |
| * Copyright (c) 1995, 2003, 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * 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 sun.tools.asm; |
| |
| import sun.tools.java.*; |
| import java.io.IOException; |
| import java.io.DataOutputStream; |
| |
| /** |
| * This class is used to assemble the local variable table. |
| * |
| * WARNING: The contents of this source file are not part of any |
| * supported API. Code that depends on them does so at its own risk: |
| * they are subject to change or removal without notice. |
| * |
| * @author Arthur van Hoff |
| */ |
| final |
| class LocalVariableTable { |
| LocalVariable locals[] = new LocalVariable[8]; |
| int len; |
| |
| /** |
| * Define a new local variable. Merge entries where possible. |
| */ |
| void define(MemberDefinition field, int slot, int from, int to) { |
| if (from >= to) { |
| return; |
| } |
| for (int i = 0 ; i < len ; i++) { |
| if ((locals[i].field == field) && (locals[i].slot == slot) && |
| (from <= locals[i].to) && (to >= locals[i].from)) { |
| locals[i].from = Math.min(locals[i].from, from); |
| locals[i].to = Math.max(locals[i].to, to); |
| return; |
| } |
| } |
| if (len == locals.length) { |
| LocalVariable newlocals[] = new LocalVariable[len * 2]; |
| System.arraycopy(locals, 0, newlocals, 0, len); |
| locals = newlocals; |
| } |
| locals[len++] = new LocalVariable(field, slot, from, to); |
| } |
| |
| /** |
| * Trim overlapping local ranges. Java forbids shadowing of |
| * locals in nested scopes, but non-nested scopes may still declare |
| * locals with the same name. Because local variable ranges are |
| * computed using flow analysis as part of assembly, it isn't |
| * possible to simply make sure variable ranges end where the |
| * enclosing lexical scope ends. This method makes sure that |
| * variables with the same name don't overlap, giving priority to |
| * fields with higher slot numbers that should have appeared later |
| * in the source. |
| */ |
| private void trim_ranges() { |
| for (int i=0; i<len; i++) { |
| for (int j=i+1; j<len; j++) { |
| if ((locals[i].field.getName()==locals[j].field.getName()) |
| && (locals[i].from <= locals[j].to) |
| && (locals[i].to >= locals[j].from)) { |
| // At this point we know that both ranges are |
| // the same name and there is also overlap or they abut |
| if (locals[i].slot < locals[j].slot) { |
| if (locals[i].from < locals[j].from) { |
| locals[i].to = Math.min(locals[i].to, locals[j].from); |
| } else { |
| // We've detected two local variables with the |
| // same name, and the one with the greater slot |
| // number starts before the other. This order |
| // reversal may happen with locals with the same |
| // name declared in both a try body and an |
| // associated catch clause. This is rare, and |
| // we give up. |
| } |
| } else if (locals[i].slot > locals[j].slot) { |
| if (locals[i].from > locals[j].from) { |
| locals[j].to = Math.min(locals[j].to, locals[i].from); |
| } else { |
| // Same situation as above; just give up. |
| } |
| } else { |
| // This case can happen if there are two variables |
| // with the same name and slot numbers, and ranges |
| // that abut. AFAIK the only way this can occur |
| // is with multiple static initializers. Punt. |
| } |
| } |
| } |
| } |
| } |
| |
| /** |
| * Write out the data. |
| */ |
| void write(Environment env, DataOutputStream out, ConstantPool tab) throws IOException { |
| trim_ranges(); |
| out.writeShort(len); |
| for (int i = 0 ; i < len ; i++) { |
| //System.out.println("pc=" + locals[i].from + ", len=" + (locals[i].to - locals[i].from) + ", nm=" + locals[i].field.getName() + ", slot=" + locals[i].slot); |
| out.writeShort(locals[i].from); |
| out.writeShort(locals[i].to - locals[i].from); |
| out.writeShort(tab.index(locals[i].field.getName().toString())); |
| out.writeShort(tab.index(locals[i].field.getType().getTypeSignature())); |
| out.writeShort(locals[i].slot); |
| } |
| } |
| } |