Java 类org.apache.bcel.generic.IFNULL 实例源码

private boolean hasManyPreceedingNullTests(int pc) {
    int ifNullTests = 0;
    BitSet seen = new BitSet();
    try {
        for (Iterator<Location> i = classContext.getCFG(method).locationIterator(); i.hasNext();) {
            Location loc = i.next();
            int pc2 = loc.getHandle().getPosition();
            if (pc2 >= pc || pc2 < pc - 30)
                continue;
            Instruction ins = loc.getHandle().getInstruction();
            if ((ins instanceof IFNONNULL || ins instanceof IFNULL || ins instanceof NullnessConversationInstruction)
                    && !seen.get(pc2)) {
                ifNullTests++;
                seen.set(pc2);
            }
        }
        boolean result = ifNullTests > 2;

        // System.out.println("Preceeding null tests " + ifNullTests + " " +
        // ifNonnullTests + " " + result);
        return result;
    } catch (CFGBuilderException e) {
        return false;
    }
}

private boolean hasManyPreceedingNullTests(int pc) {
    int ifNullTests = 0;
    BitSet seen = new BitSet();
    try {
        for (Iterator<Location> i = classContext.getCFG(method).locationIterator(); i.hasNext();) {
            Location loc = i.next();
            int pc2 = loc.getHandle().getPosition();
            if (pc2 >= pc || pc2 < pc - 30)
                continue;
            Instruction ins = loc.getHandle().getInstruction();
            if ((ins instanceof IFNONNULL || ins instanceof IFNULL || ins instanceof NullnessConversationInstruction)
                    && !seen.get(pc2)) {
                ifNullTests++;
                seen.set(pc2);
            }
        }
        boolean result = ifNullTests > 2;

        // System.out.println("Preceeding null tests " + ifNullTests + " " +
        // ifNonnullTests + " " + result);
        return result;
    } catch (CFGBuilderException e) {
        return false;
    }
}

@Override
public MatchResult match(InstructionHandle handle, ConstantPoolGen cpg, ValueNumberFrame before, ValueNumberFrame after,
        BindingSet bindingSet) throws DataflowAnalysisException {

    // Instruction must be IFNULL or IFNONNULL.
    Instruction ins = handle.getInstruction();
    if (!(ins instanceof IFNULL || ins instanceof IFNONNULL))
        return null;

    // Ensure reference used is consistent with previous uses of
    // same variable.
    LocalVariable ref = new LocalVariable(before.getTopValue());
    return addOrCheckDefinition(ref, bindingSet);
}

@Override
public MatchResult match(InstructionHandle handle, ConstantPoolGen cpg, ValueNumberFrame before, ValueNumberFrame after,
        BindingSet bindingSet) throws DataflowAnalysisException {

    // Instruction must be IFNULL or IFNONNULL.
    Instruction ins = handle.getInstruction();
    if (!(ins instanceof IFNULL || ins instanceof IFNONNULL))
        return null;

    // Ensure reference used is consistent with previous uses of
    // same variable.
    LocalVariable ref = new LocalVariable(before.getTopValue());
    return addOrCheckDefinition(ref, bindingSet);
}

void insertAbortedCheck(MethodGen m, InstructionList il,
    InstructionHandle pos) {
    // Generates:
    //       if (cashmere.getParent() != null && cashmere.getParent().aborted) {
    //           throw new ibis.cashmere.impl.aborts.AbortException();
    //       }
    InstructionHandle abo = insertThrowAbort(m, il, pos);

    il.insert(abo, getCashmere(ins_f));
    il.insert(abo, ins_f.createInvoke("ibis.cashmere.impl.Cashmere", "getParent",
        irType, Type.NO_ARGS, Constants.INVOKEVIRTUAL));

    // test for null (root job)
    il.insert(abo, new IFNULL(pos));

    il.insert(abo, getCashmere(ins_f));
    il.insert(abo, ins_f.createInvoke("ibis.cashmere.impl.Cashmere", "getParent",
        irType, Type.NO_ARGS, Constants.INVOKEVIRTUAL));

    il.insert(abo, ins_f.createFieldAccess(
        "ibis.cashmere.impl.spawnSync.InvocationRecord", "aborted",
        Type.BOOLEAN, Constants.GETFIELD));
    il.insert(abo, new IFEQ(pos));

    /*
     ////@@@@@@@@@@2 this needs fixing :-(
     // Test for parent.eek, if non-null, throw it (exception in inlet).
     il.insert(abo, getCashmere(ins_f));
     il.insert(abo, ins_f.createInvoke("ibis.cashmere.impl.Cashmere", "getParent",
     irType, Type.NO_ARGS, Constants.INVOKEVIRTUAL));
     il.insert(abo, ins_f.createFieldAccess(
     "ibis.cashmere.impl.spawnSync.InvocationRecord", "eek",
     new ObjectType("java.lang.Throwable"), Constants.GETFIELD));
     il.insert(abo, new IFNULL(abo));
     il.insert(abo, getCashmere(ins_f));
     il.insert(abo, ins_f.createInvoke("ibis.cashmere.impl.Cashmere", "getParent",
     irType, Type.NO_ARGS, Constants.INVOKEVIRTUAL));
     il.insert(abo, ins_f.createFieldAccess(
     "ibis.cashmere.impl.spawnSync.InvocationRecord", "eek",
     new ObjectType("java.lang.Throwable"), Constants.GETFIELD));

     il.insert(abo, new ATHROW());
     */
}

@Override
public boolean acceptBranch(Edge edge, InstructionHandle source) {
    boolean isIfNull = (source.getInstruction() instanceof IFNULL);
    return edge.getType() == (isIfNull ? IFCMP_EDGE : FALL_THROUGH_EDGE);
}

@Override
public boolean acceptBranch(Edge edge, InstructionHandle source) {
    boolean isIfNull = (source.getInstruction() instanceof IFNULL);
    return edge.getType() == (isIfNull ? IFCMP_EDGE : FALL_THROUGH_EDGE);
}