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139 lines
4.2 KiB
139 lines
4.2 KiB
/* ConditionalBlock Copyright (C) 1998-2002 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.decompiler.TabbedPrintWriter;
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import net.sf.jode.expr.Expression;
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/**
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* An ConditionalBlock is the structured block representing an if
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* instruction. The else part may be null.
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*/
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public class ConditionalBlock extends InstructionContainer {
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/**
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* The loads that are on the stack before instr is executed.
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*/
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VariableStack stack;
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EmptyBlock trueBlock;
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public void checkConsistent() {
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super.checkConsistent();
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if (!(trueBlock instanceof EmptyBlock))
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throw new InternalError("Inconsistency");
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}
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/**
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* Creates a new if conditional block.
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*/
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public ConditionalBlock(Expression cond) {
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super(cond);
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/* cond is a CompareBinary or CompareUnary operator, so no
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* check for LocalVarOperator (for condJump) is needed here.
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*/
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trueBlock = new EmptyBlock();
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trueBlock.outer = this;
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}
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/* The implementation of getNext[Flow]Block is the standard
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* implementation
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*/
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/**
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* Sets the successors of this structured block. This should be only
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* called once, by FlowBlock.setSuccessors().
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*/
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public void setSuccessors(Jump[] jumps) {
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if (jumps.length != 2) {
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/* A conditional block can only exactly two jumps. */
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throw new IllegalArgumentException("Not exactly two jumps.");
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}
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trueBlock.setJump(jumps[0]);
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setJump(jumps[1]);
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}
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/**
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* Returns all sub block of this structured block.
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*/
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public StructuredBlock[] getSubBlocks() {
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return new StructuredBlock[] { trueBlock };
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}
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/**
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* Replaces the given sub block with a new block.
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* @param oldBlock the old sub block.
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* @param newBlock the new sub block.
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* @return false, if oldBlock wasn't a direct sub block.
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*/
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public boolean replaceSubBlock(StructuredBlock oldBlock,
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StructuredBlock newBlock) {
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throw new InternalError("replaceSubBlock on ConditionalBlock");
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}
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/**
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* This does take the instr into account and modifies stack
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* accordingly. It then calls super.mapStackToLocal.
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* @param stack the stack before the instruction is called
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* @return stack the stack afterwards.
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*/
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public VariableStack mapStackToLocal(VariableStack stack) {
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VariableStack newStack;
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int params = instr.getFreeOperandCount();
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if (params > 0) {
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this.stack = stack.peek(params);
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newStack = stack.pop(params);
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} else
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newStack = stack;
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trueBlock.jump.stackMap = newStack;
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if (jump != null) {
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jump.stackMap = newStack;
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return null;
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}
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return newStack;
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}
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public void removePush() {
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if (stack != null)
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instr = stack.mergeIntoExpression(instr);
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trueBlock.removePush();
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}
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/**
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* Print the source code for this structured block.
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*/
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public void dumpInstruction(TabbedPrintWriter writer)
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throws java.io.IOException
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{
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writer.print("IF (");
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instr.dumpExpression(TabbedPrintWriter.EXPL_PAREN, writer);
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writer.println(")");
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writer.tab();
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trueBlock.dumpSource(writer);
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writer.untab();
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}
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public boolean doTransformations() {
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StructuredBlock last = flowBlock.lastModified;
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return super.doTransformations()
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|| CombineIfGotoExpressions.transform(this, last)
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|| CreateIfThenElseOperator.createFunny(this, last);
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}
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}
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