sootup.java.bytecode.interceptors.UnusedLocalEliminator Maven / Gradle / Ivy
package sootup.java.bytecode.interceptors;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 1997-2020 Raja Vallée-Rai, Marcus Nachtigall and others
* %%
* 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.LinkedHashSet;
import java.util.Set;
import javax.annotation.Nonnull;
import sootup.core.jimple.basic.Local;
import sootup.core.jimple.basic.Value;
import sootup.core.jimple.common.stmt.Stmt;
import sootup.core.model.Body;
import sootup.core.transform.BodyInterceptor;
import sootup.core.views.View;
/**
* A BodyTransformer that removes all unused local variables from a given Body.
*
* @author Marcus Nachtigall
*/
public class UnusedLocalEliminator implements BodyInterceptor {
/**
* Removes unused local variables from the List of Stmts of the given {@link Body}. Complexity is
* linear with respect to the statements.
*
* @param builder the BodyBuilder.
*/
@Override
public void interceptBody(@Nonnull Body.BodyBuilder builder, @Nonnull View view) {
Set locals = new LinkedHashSet<>();
// Traverse statements copying all used uses and defs
for (Stmt stmt : builder.getStmtGraph()) {
for (Value value : stmt.getUsesAndDefs()) {
if (value instanceof Local) {
Local local = (Local) value;
locals.add(local);
}
}
}
builder.setLocals(locals);
}
}