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123 lines
3.6 KiB
123 lines
3.6 KiB
/* CreateCheckNull Copyright (C) 1999-2002 Jochen Hoenicke.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; see the file COPYING.LESSER. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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*/
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package net.sf.jode.flow;
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import net.sf.jode.expr.*;
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import net.sf.jode.type.Type;
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import net.sf.jode.decompiler.LocalInfo;
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public class CreateCheckNull {
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/* Situation:
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*
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* javac:
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* DUP
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* POP.getClass();
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*
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* jikes:
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* DUP
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* if (POP == null)
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* throw null;
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*/
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/**
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* Transforms the code
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* <pre>
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* DUP
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* POP.getClass()
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* </pre>
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* to a CheckNullOperator. This is what javac generates when it
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* calls ".new" on an operand.
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*/
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public static boolean transformJavac(InstructionContainer ic,
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StructuredBlock last) {
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if (!(last.outer instanceof SequentialBlock)
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|| !(ic.getInstruction() instanceof Operator)
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|| !(last.outer.getSubBlocks()[0] instanceof SpecialBlock))
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return false;
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SpecialBlock dup = (SpecialBlock) last.outer.getSubBlocks()[0];
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if (dup.type != SpecialBlock.DUP
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|| dup.count != 1 || dup.depth != 0)
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return false;
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Operator ce = (Operator) ic.getInstruction();
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if (!(ce.getOperator() instanceof PopOperator)
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|| !(ce.getSubExpressions()[0] instanceof InvokeOperator))
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return false;
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InvokeOperator getClassCall
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= (InvokeOperator) ce.getSubExpressions()[0];
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if (!getClassCall.getMethodName().equals("getClass")
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|| !(getClassCall.getMethodType().toString()
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.equals("()Ljava/lang/Class;")))
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return false;
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LocalInfo li = new LocalInfo();
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ic.setInstruction(new CheckNullOperator(Type.tUObject, li));
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last.replace(last.outer);
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return true;
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}
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/**
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* Transforms the code
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* <pre>
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* DUP
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* if (POP == null) {
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* throw null
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* }
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* </pre>
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* to a CheckNullOperator. This is what jikes generates when it
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* calls ".new" on an operand.
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*/
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public static boolean transformJikes(IfThenElseBlock ifBlock,
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StructuredBlock last) {
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if (!(last.outer instanceof SequentialBlock)
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|| !(last.outer.getSubBlocks()[0] instanceof SpecialBlock)
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|| ifBlock.elseBlock != null
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|| !(ifBlock.thenBlock instanceof ThrowBlock))
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return false;
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SpecialBlock dup = (SpecialBlock) last.outer.getSubBlocks()[0];
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if (dup.type != SpecialBlock.DUP
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|| dup.count != 1 || dup.depth != 0)
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return false;
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if (!(ifBlock.cond instanceof CompareUnaryOperator))
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return false;
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CompareUnaryOperator cmpOp = (CompareUnaryOperator) ifBlock.cond;
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if (cmpOp.getOperatorIndex() != Operator.EQUALS_OP
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|| !(cmpOp.getCompareType().isOfType(Type.tUObject)))
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return false;
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LocalInfo li = new LocalInfo();
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InstructionContainer ic =
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new InstructionBlock(new CheckNullOperator(Type.tUObject, li));
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ic.moveJump(ifBlock.jump);
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if (last == ifBlock) {
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ic.replace(last.outer);
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last = ic;
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} else {
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ic.replace(ifBlock);
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last.replace(last.outer);
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}
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return true;
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}
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}
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