/*
* Copyright (c) 2011, IETR/INSA of Rennes
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither the name of the IETR/INSA of Rennes nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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*/
package net.sf.orcc.ir.transform;
import java.util.ArrayList;
import java.util.List;
import net.sf.orcc.OrccRuntimeException;
import net.sf.orcc.ir.Block;
import net.sf.orcc.ir.BlockBasic;
import net.sf.orcc.ir.BlockIf;
import net.sf.orcc.ir.BlockWhile;
import net.sf.orcc.ir.ExprUnary;
import net.sf.orcc.ir.Expression;
import net.sf.orcc.ir.Instruction;
import net.sf.orcc.ir.IrFactory;
import net.sf.orcc.ir.OpUnary;
import net.sf.orcc.ir.Predicate;
import net.sf.orcc.ir.Procedure;
import net.sf.orcc.ir.util.AbstractIrVisitor;
import net.sf.orcc.ir.util.IrUtil;
import net.sf.orcc.util.util.EcoreHelper;
import org.eclipse.emf.ecore.util.EcoreUtil;
/**
* This class performs the inverse of if-conversion on the given procedure.
*
* @author Matthieu Wipliez
*
*/
public class IfDeconverter extends AbstractIrVisitor<Object> {
private Predicate currentPredicate;
private List<BlockIf> blockIfList;
@Override
public Object caseBlockBasic(BlockBasic block) {
Procedure procedure = EcoreHelper.getContainerOfType(block,
Procedure.class);
BlockBasic targetBlock = null;
List<Instruction> instructions = block.getInstructions();
while (!instructions.isEmpty()) {
Instruction inst = instructions.get(0);
Predicate predicate = inst.getPredicate();
if (!predicate.isSameAs(currentPredicate)) {
// deletes the current predicate
if (currentPredicate != null) {
IrUtil.delete(currentPredicate);
}
// updates the target block
targetBlock = updateTargetBlock(procedure, predicate);
}
// deletes the predicate of the instruction
IrUtil.delete(predicate);
// moves the instruction
targetBlock.getInstructions().add(inst);
}
// deletes the current predicate
if (currentPredicate != null) {
IrUtil.delete(currentPredicate);
}
// remove this block
EcoreUtil.remove(block);
return null;
}
@Override
public Object caseBlockWhile(BlockWhile blockWhile) {
throw new OrccRuntimeException("unsupported BlockWhile");
}
@Override
public Object caseProcedure(Procedure procedure) {
// do not perform if-deconversion if procedure contains whiles
if (EcoreHelper.getObjects(procedure, BlockWhile.class).iterator()
.hasNext()) {
return null;
}
blockIfList = new ArrayList<BlockIf>();
// initialized to "null" so that the first empty predicate will create
// an unconditional block
currentPredicate = null;
List<Block> blocks = procedure.getBlocks();
if (!blocks.isEmpty()) {
doSwitch(blocks.get(0));
}
return null;
}
/**
* Returns the list of blocks that matches the given condition (if any).
*
* @param parentBlocks
* list of blocks to which the "if" we're looking for belongs
* @param condition
* a condition
* @return the list of blocks that matches the given condition, or
* <code>null</code>
*/
private List<Block> findBlocks(List<Block> parentBlocks, Expression condition) {
for (BlockIf blockIf : blockIfList) {
List<Block> blocks = EcoreHelper.getContainingList(blockIf);
if (EcoreUtil.equals(condition, blockIf.getCondition())
&& parentBlocks == blocks) {
return blockIf.getThenBlocks();
} else {
if (condition.isExprUnary()) {
ExprUnary unary = (ExprUnary) condition;
Expression expr = unary.getExpr();
if (unary.getOp() == OpUnary.LOGIC_NOT
&& EcoreUtil.equals(expr, blockIf.getCondition())
&& parentBlocks == blocks) {
return blockIf.getElseBlocks();
}
}
}
}
return null;
}
/**
* Updates targetBlock according to the given predicate.
*
* @param procedure
* the current procedure
* @param predicate
* a predicate
*/
private BlockBasic updateTargetBlock(Procedure procedure,
Predicate predicate) {
currentPredicate = IrFactory.eINSTANCE.createPredicate();
List<Block> parentBlocks = procedure.getBlocks();
if (predicate.isEmpty()) {
// unconditioned predicate => forgets all ifs
blockIfList.clear();
// creates a new block
BlockBasic block = IrFactory.eINSTANCE.createBlockBasic();
procedure.getBlocks().add(block);
return block;
} else {
for (Expression condition : predicate.getExpressions()) {
List<Block> blocks = findBlocks(parentBlocks, condition);
if (blocks == null) {
// create a new if
BlockIf blockIf = IrFactory.eINSTANCE.createBlockIf();
blockIf.setCondition(IrUtil.copy(condition));
blockIf.setJoinBlock(IrFactory.eINSTANCE.createBlockBasic());
blockIfList.add(blockIf);
parentBlocks.add(blockIf);
// use the blocks of the "then" branch
parentBlocks = blockIf.getThenBlocks();
} else {
parentBlocks = blocks;
}
currentPredicate.add(IrUtil.copy(condition));
}
return IrUtil.getLast(parentBlocks);
}
}
}