org.jacoco.core.internal.instr.FieldProbeArrayStrategy.java Source code

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Here is the source code for org.jacoco.core.internal.instr.FieldProbeArrayStrategy.java

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/*******************************************************************************
 * Copyright (c) 2009, 2015 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.instr;

import org.jacoco.core.runtime.IExecutionDataAccessorGenerator;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

/**
 * The strategy for regular classes and Java 8 interfaces which adds a static
 * field to hold the probe array and a static initialization method requesting
 * the probe array from the runtime.
 */
class FieldProbeArrayStrategy implements IProbeArrayStrategy {

    /**
     * Frame stack with a single boolean array.
     */
    private static final Object[] FRAME_STACK_ARRZ = new Object[] { InstrSupport.DATAFIELD_DESC };

    /**
     * Empty frame locals.
     */
    private static final Object[] FRAME_LOCALS_EMPTY = new Object[0];

    private final String className;
    private final long classId;
    private final boolean withFrames;
    private final int fieldAccess;
    private final IExecutionDataAccessorGenerator accessorGenerator;

    FieldProbeArrayStrategy(final String className, final long classId, final boolean withFrames,
            final int fieldAccess, final IExecutionDataAccessorGenerator accessorGenerator) {
        this.className = className;
        this.classId = classId;
        this.withFrames = withFrames;
        this.fieldAccess = fieldAccess;
        this.accessorGenerator = accessorGenerator;
    }

    public int storeInstance(final MethodVisitor mv, final int variable) {
        mv.visitMethodInsn(Opcodes.INVOKESTATIC, className, InstrSupport.INITMETHOD_NAME,
                InstrSupport.INITMETHOD_DESC, false);
        mv.visitVarInsn(Opcodes.ASTORE, variable);
        return 1;
    }

    public void addMembers(final ClassVisitor cv, final int probeCount) {
        createDataField(cv);
        createInitMethod(cv, probeCount);
    }

    private void createDataField(final ClassVisitor cv) {
        cv.visitField(fieldAccess, InstrSupport.DATAFIELD_NAME, InstrSupport.DATAFIELD_DESC, null, null);
    }

    private void createInitMethod(final ClassVisitor cv, final int probeCount) {
        final MethodVisitor mv = cv.visitMethod(InstrSupport.INITMETHOD_ACC, InstrSupport.INITMETHOD_NAME,
                InstrSupport.INITMETHOD_DESC, null, null);
        mv.visitCode();

        // Load the value of the static data field:
        mv.visitFieldInsn(Opcodes.GETSTATIC, className, InstrSupport.DATAFIELD_NAME, InstrSupport.DATAFIELD_DESC);
        mv.visitInsn(Opcodes.DUP);

        // Stack[1]: [Z
        // Stack[0]: [Z

        // Skip initialization when we already have a data array:
        final Label alreadyInitialized = new Label();
        mv.visitJumpInsn(Opcodes.IFNONNULL, alreadyInitialized);

        // Stack[0]: [Z

        mv.visitInsn(Opcodes.POP);
        final int size = genInitializeDataField(mv, probeCount);

        // Stack[0]: [Z

        // Return the class' probe array:
        if (withFrames) {
            mv.visitFrame(Opcodes.F_NEW, 0, FRAME_LOCALS_EMPTY, 1, FRAME_STACK_ARRZ);
        }
        mv.visitLabel(alreadyInitialized);
        mv.visitInsn(Opcodes.ARETURN);

        mv.visitMaxs(Math.max(size, 2), 0); // Maximum local stack size is 2
        mv.visitEnd();
    }

    /**
     * Generates the byte code to initialize the static coverage data field
     * within this class.
     * 
     * The code will push the [Z data array on the operand stack.
     * 
     * @param mv
     *            generator to emit code to
     */
    private int genInitializeDataField(final MethodVisitor mv, final int probeCount) {
        final int size = accessorGenerator.generateDataAccessor(classId, className, probeCount, mv);

        // Stack[0]: [Z

        mv.visitInsn(Opcodes.DUP);

        // Stack[1]: [Z
        // Stack[0]: [Z

        mv.visitFieldInsn(Opcodes.PUTSTATIC, className, InstrSupport.DATAFIELD_NAME, InstrSupport.DATAFIELD_DESC);

        // Stack[0]: [Z

        return Math.max(size, 2); // Maximum local stack size is 2
    }

}