# MethodSanitizer.java

    /*******************************************************************************
     * Copyright (c) 2009, 2013 Mountainminds GmbH & Co. KG and Contributors
     * All rights reserved. This program and the accompanying materials
     * are made available under the terms of the Eclipse Public License v1.0
     * which accompanies this distribution, and is available at
     * http://www.eclipse.org/legal/epl-v10.html
     *
     * Contributors:
     *    Marc R. Hoffmann - initial API and implementation
     *
     *******************************************************************************/
    package org.jacoco.core.internal.flow;

    import org.objectweb.asm.Label;
    import org.objectweb.asm.MethodVisitor;
    import org.objectweb.asm.commons.JSRInlinerAdapter;

    /**
     * This method visitor fixes two potential issues with Java byte code:
     *
     * <ul>
     * <li>Remove JSR/RET instructions by inlining subroutines which are deprecated
     * since Java 6. The RET statement complicates control flow analysis as the jump
     * target is not explicitly given.</li>
     * <li>Remove code attributes line number and local variable name if they point
     * to invalid offsets which some tools create. When writing out such invalid
     * labels with ASM class files do not verify any more.</li>
     * </ul>
     */
    class MethodSanitizer extends JSRInlinerAdapter {

    	MethodSanitizer(final MethodVisitor mv, final int access,
    			final String name, final String desc, final String signature,
    			final String[] exceptions) {
    		super(mv, access, name, desc, signature, exceptions);
    	}

    	@Override
    	public void visitLocalVariable(final String name, final String desc,
    			final String signature, final Label start, final Label end,
    			final int index) {
    		// Here we rely on the usage of the info fields by the tree API. If the
    		// labels have been properly used before the info field contains a
    		// reference to the LabelNode, otherwise null.
    		if (start.info != null && end.info != null) {
    			super.visitLocalVariable(name, desc, signature, start, end, index);
    		}
    	}

    	@Override
    	public void visitLineNumber(final int line, final Label start) {
    		// Here we rely on the usage of the info fields by the tree API. If the
    		// labels have been properly used before the info field contains a
    		// reference to the LabelNode, otherwise null.
    		if (start.info != null) {
    			super.visitLineNumber(line, start);
    		}
    	}

    }