MethodProbesVisitor.java

/*******************************************************************************
 * Copyright (c) 2009, 2025 Mountainminds GmbH & Co. KG and Contributors
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *    Marc R. Hoffmann - initial API and implementation
 *
 *******************************************************************************/
package org.jacoco.core.internal.flow;

import org.jacoco.core.internal.instr.InstrSupport;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.tree.MethodNode;

/**
 * A {@link MethodVisitor} with additional methods to get probe insertion
 * information.
 */
public abstract class MethodProbesVisitor extends MethodVisitor {

    /**
     * New visitor instance without delegate visitor.
     */
    public MethodProbesVisitor() {
        this(null);
    }

    /**
     * New visitor instance that delegates to the given visitor.
     *
     * @param mv
     *            optional next visitor in chain
     */
    public MethodProbesVisitor(final MethodVisitor mv) {
        super(InstrSupport.ASM_API_VERSION, mv);
    }

    /**
     * Visits an unconditional probe that should be inserted at the current
     * position.
     *
     * @param probeId
     *            id of the probe to insert
     */
    @SuppressWarnings("unused")
    public void visitProbe(final int probeId) {
    }

    /**
     * Visits a jump instruction. A probe with the given id should be inserted
     * in a way that it is executed only when the jump to the given label is
     * executed.
     *
     * @param opcode
     *            the opcode of the type instruction to be visited. This opcode
     *            is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ,
     *            IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE,
     *            IF_ACMPEQ, IF_ACMPNE, GOTO, IFNULL or IFNONNULL.
     * @param label
     *            the operand of the instruction to be visited. This operand is
     *            a label that designates the instruction to which the jump
     *            instruction may jump.
     * @param probeId
     *            id of the probe
     * @param frame
     *            stackmap frame status after the execution of the jump
     *            instruction. The instance is only valid with the call of this
     *            method.
     * @see MethodVisitor#visitJumpInsn(int, Label)
     */
    @SuppressWarnings("unused")
    public void visitJumpInsnWithProbe(final int opcode, final Label label,
            final int probeId, final IFrame frame) {
    }

    /**
     * Visits a zero operand instruction with a probe. This event is used only
     * for instructions that terminate the method. Therefore the probe must be
     * inserted before the actual instruction.
     *
     * @param opcode
     *            the opcode of the instruction to be visited. This opcode is
     *            either IRETURN, LRETURN, FRETURN, DRETURN, ARETURN, RETURN or
     *            ATHROW.
     * @param probeId
     *            id of the probe
     * @see MethodVisitor#visitInsn(int)
     */
    @SuppressWarnings("unused")
    public void visitInsnWithProbe(final int opcode, final int probeId) {
    }

    /**
     * Visits a TABLESWITCH instruction with optional probes for each target
     * label. Implementations can be optimized based on the fact that the same
     * target labels will always have the same probe id within a call to this
     * method. The probe id for each label can be obtained with
     * {@link LabelInfo#getProbeId(Label)}.
     *
     * @param min
     *            the minimum key value.
     * @param max
     *            the maximum key value.
     * @param dflt
     *            beginning of the default handler block.
     * @param labels
     *            beginnings of the handler blocks. <code>labels[i]</code> is
     *            the beginning of the handler block for the
     *            <code>min + i</code> key.
     * @param frame
     *            stackmap frame status after the execution of the switch
     *            instruction. The instance is only valid with the call of this
     *            method.
     * @see MethodVisitor#visitTableSwitchInsn(int, int, Label, Label[])
     */
    @SuppressWarnings("unused")
    public void visitTableSwitchInsnWithProbes(final int min, final int max,
            final Label dflt, final Label[] labels, final IFrame frame) {
    }

    /**
     * Visits a LOOKUPSWITCH instruction with optional probes for each target
     * label. Implementations can be optimized based on the fact that the same
     * target labels will always have the same probe id within a call to this
     * method. The probe id for each label can be obtained with
     * {@link LabelInfo#getProbeId(Label)}.
     *
     * @param dflt
     *            beginning of the default handler block.
     * @param keys
     *            the values of the keys.
     * @param labels
     *            beginnings of the handler blocks. <code>labels[i]</code> is
     *            the beginning of the handler block for the
     *            <code>keys[i]</code> key.
     * @param frame
     *            stackmap frame status after the execution of the switch
     *            instruction. The instance is only valid with the call of this
     *            method.
     * @see MethodVisitor#visitLookupSwitchInsn(Label, int[], Label[])
     */
    @SuppressWarnings("unused")
    public void visitLookupSwitchInsnWithProbes(final Label dflt,
            final int[] keys, final Label[] labels, final IFrame frame) {
    }

    /**
     * This method can be overwritten to hook into the process of emitting the
     * instructions of this method as <code>visitX()</code> events.
     *
     * @param methodNode
     *            the content to emit
     * @param methodVisitor
     *            A visitor to emit the content to. Note that this is not
     *            necessarily this visitor instance but some wrapper which
     *            calculates the probes.
     */
    public void accept(final MethodNode methodNode,
            final MethodVisitor methodVisitor) {
        methodNode.accept(methodVisitor);
    }

}