sootup.java.bytecode.interceptors.UnreachableCodeEliminator Maven / Gradle / Ivy
package sootup.java.bytecode.interceptors;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 1997-2020 Raja Vallée-Rai, Christian Brüggemann, Zun Wang
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 2.1 of the
* License, or (at your option) any later version.
*
* This program 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 Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import java.util.*;
import javax.annotation.Nonnull;
import sootup.core.graph.StmtGraph;
import sootup.core.jimple.common.stmt.Stmt;
import sootup.core.model.Body;
import sootup.core.transform.BodyInterceptor;
import sootup.core.views.View;
/**
* A BodyInterceptor that removes all unreachable stmts from the given Body.
*
* @author Zun Wang
*/
public class UnreachableCodeEliminator implements BodyInterceptor {
@Override
public void interceptBody(@Nonnull Body.BodyBuilder builder, @Nonnull View view) {
StmtGraph graph = builder.getStmtGraph();
Deque queue = new ArrayDeque<>();
queue.add(graph.getStartingStmt());
// calculate all reachable stmts
Set reachableStmts = new HashSet<>();
while (!queue.isEmpty()) {
Stmt stmt = queue.removeFirst();
reachableStmts.add(stmt);
for (Stmt succ : graph.getAllSuccessors(stmt)) {
if (!reachableStmts.contains(succ)) {
queue.add(succ);
}
}
}
// remove unreachable stmts from StmtGraph
Queue removeQ = new ArrayDeque<>();
for (Stmt stmt : graph.getNodes()) {
if (!reachableStmts.contains(stmt)) {
removeQ.add(stmt);
}
}
for (Stmt stmt : removeQ) {
builder.removeStmt(stmt);
}
}
}