/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.dev.jjs.impl.gflow.liveness;
import com.google.gwt.dev.jjs.ast.JLocal;
import com.google.gwt.dev.jjs.ast.JParameter;
import com.google.gwt.dev.jjs.ast.JVariable;
import com.google.gwt.dev.jjs.impl.gflow.AssumptionMap;
import com.google.gwt.dev.jjs.impl.gflow.AssumptionUtil;
import com.google.gwt.dev.jjs.impl.gflow.IntegratedFlowFunction;
import com.google.gwt.dev.jjs.impl.gflow.TransformationFunction.Transformation;
import com.google.gwt.dev.jjs.impl.gflow.cfg.Cfg;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgEdge;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgNode;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgTransformer;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgWriteNode;
/**
*
*/
public class LivenessIntegratedFlowFunction implements
IntegratedFlowFunction<CfgNode<?>, CfgEdge, CfgTransformer, Cfg,
LivenessAssumption> {
private final LivenessFlowFunction flowFunction = new LivenessFlowFunction();
@Override
public Transformation<CfgTransformer, Cfg>
interpretOrReplace(CfgNode<?> node, Cfg graph,
AssumptionMap<CfgEdge, LivenessAssumption> assumptionMap) {
LivenessAssumption assumptions = AssumptionUtil.join(
graph.getOutEdges(node), assumptionMap);
if (node instanceof CfgWriteNode) {
CfgWriteNode write = (CfgWriteNode) node;
JVariable variable = write.getTargetVariable();
if ((variable instanceof JLocal || variable instanceof JParameter) &&
!isLive(assumptions, variable) && write.getValue() != null) {
return new LivenessTransformation(graph, write);
}
}
flowFunction.interpret(node, graph, assumptionMap);
return null;
}
private boolean isLive(LivenessAssumption assumptions, JVariable variable) {
return assumptions != null && assumptions.isLive(variable);
}
}