HeapNEW.java

package com.foursquare.heapaudit;

import org.objectweb.asm.Label;
import org.objectweb.asm.MethodAdapter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

class HeapNEW extends HeapUtil {

    // Allocations by NEW are triggered via calls to both visitTypeInsn and
    // visitMethodInsn(INVOKESPECIAL) where the top of the stack after the first
    // call to visitTypeInsn contains an uninitialized reference to the newly
    // allocated object. The reference to the object can only be touched (with
    // the exception of (DUP/SWAP/POP operations) after it is fully initialized
    // by the call to visitMethodInsn(INVOKESPECIAL). The top of the stack when
    // calling visitMethodInsn(INVOKESPECIAL) contains the reference to the
    // uninitialized newly allocated object and all the parameter values for the
    // constructor arguments.

    static void before(boolean debug,
                       boolean trace,
                       MethodAdapter mv,
                       HeapVariables lvs,
                       String signature) {

        log(debug,
            trace,
            mv,
            "\tNEW.before");

        Type[] args = Type.getArgumentTypes(signature);

        int[] vars = new int[args.length];

        Label start = new Label();

        Label end = new Label();

        mv.visitLabel(start);

        for (int i = args.length - 1; i >= 0; --i) {

            vars[i] = lvs.define(args[i],
                                 start,
                                 end);

            // STACK [...|obj|...|arg]
            mv.visitVarInsn(args[i].getOpcode(Opcodes.ISTORE),
                            vars[i]);
            // STACK [...|obj|...]

        }

        // STACK [...|obj]
        mv.visitInsn(Opcodes.DUP);
        // STACK [...|obj|obj]

        for (int i = 0; i < args.length; ++i) {

            // STACK [...|obj|obj|...]
            mv.visitVarInsn(args[i].getOpcode(Opcodes.ILOAD),
                            vars[i]);
            // STACK [...|obj|obj|...|arg]

        }

        mv.visitLabel(end);

    }

    static void after(boolean debug,
                      boolean trace,
                      MethodAdapter mv,
                      String owner) {

        log(debug,
            trace,
            mv,
            "\tNEW.after");

        Label cleanup = new Label();

        Label finish = new Label();

        if (HeapSettings.conditional) {

            // STACK: [...|obj]
            visitCheck(mv,
                       cleanup);
            // STACK: [...|obj]

        }

        // STACK: [...|obj]
        mv.visitLdcInsn(-1);
        // STACK: [...|obj|count]
        mv.visitLdcInsn(owner);
        // STACK: [...|obj|count|type]
        mv.visitLdcInsn((long)-1);
        // STACK: [...|obj|count|type|size]
        mv.visitMethodInsn(Opcodes.INVOKESTATIC,
                           "com/foursquare/heapaudit/HeapUtil",
                           "record",
                           "(Ljava/lang/Object;ILjava/lang/String;J)V");
        // STACK: [...]

        if (HeapSettings.conditional) {

            visitCleanup(mv,
                         cleanup,
                         finish);
            // STACK: [...|obj]
            mv.visitInsn(Opcodes.POP);
            // STACK: [...]
            visitFinish(mv,
                        finish);
            // STACK: [...]

        }

    }

}