Examples of edu.umd.cs.findbugs.ba.vna.AvailableLoad

edu.umd.cs.findbugs.ba.vna.AvailableLoad
An AvailableLoad indicates a field and (optionally) object reference for which a value is available. It is used to implement redundant load elimination and forward substitution in ValueNumberAnalysis. The idea is that programmers often reload fields unnecessarily when they "know" that the value will not change. In order to deduce the intended meaning of such code, our analyses need to figure out that such loads return the same value.

AvailableLoad objects may be used as keys in both hash and tree sets and maps. @author David Hovemeyer @see ValueNumberAnalysis

        XField field = XFactory.createXField(obj, cpg);
        if (nullValueStored != null && ValueNumberAnalysisFeatures.REDUNDANT_LOAD_ELIMINATION) {
            try {
                ValueNumberFrame vnaFrameBefore = vnaDataflow.getFactAtLocation(getLocation());
                ValueNumber refValue = vnaFrameBefore.getStackValue(1);
                AvailableLoad load = new AvailableLoad(refValue, field);
                ValueNumberFrame vnaFrameAfter = vnaDataflow.getFactAfterLocation(getLocation());
                ValueNumber[] newValueNumbersForField = vnaFrameAfter.getAvailableLoad(load);
                if (newValueNumbersForField != null && trackValueNumbers) {
                    for (ValueNumber v : newValueNumbersForField) {
                        getFrame().setKnownValue(v, nullValueStored);

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                if (propagatePhiNodeInformation && targetVnaFrame.phiNodeForLoads) {
                    if (DEBUG) {
                        System.out.println("Is phi node for loads");
                    }
                    for (ValueNumber v : fact.getKnownValues()) {
                        AvailableLoad loadForV = sourceVnaFrame.getLoad(v);
                        if (DEBUG) {
                            System.out.println("  " + v + " for " + loadForV);
                        }
                        if (loadForV != null) {
                            ValueNumber[] matchingValueNumbers = targetVnaFrame.getAvailableLoad(loadForV);

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        final int targetNumSlots = targetVnaFrame.getNumSlots();
        final int prefixNumSlots = Math.min(frame.getNumSlots(), prevVnaFrame.getNumSlots());


        if (trackValueNumbers) {
            AvailableLoad loadForV = prevVnaFrame.getLoad(replaceMe);
            if (DEBUG && loadForV != null) {
                System.out.println("For " + replaceMe + " availableLoad is " + loadForV);
                ValueNumber[] matchingValueNumbers = targetVnaFrame.getAvailableLoad(loadForV);
                if (matchingValueNumbers != null) {
                    for (ValueNumber v2 : matchingValueNumbers) {

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                    }


                } // for all slots


                for (ValueNumber blockVN : blockValueNumberFrame.valueNumbersForLoads()) {
                    AvailableLoad load = blockValueNumberFrame.getLoad(blockVN);
                    if (load == null) {
                        continue;
                    }
                    ValueNumber[] targetVNs = targetValueNumberFrame.getAvailableLoad(load);
                    if (targetVNs != null) {
                        for (ValueNumber targetVN : targetVNs) {
                            if (targetVN.hasFlag(ValueNumber.PHI_NODE) && fact.isUnconditionallyDereferenced(targetVN)
                                    && !fact.isUnconditionallyDereferenced(blockVN)) {
                                // Block VN is also dereferenced
                                // unconditionally.
                                AvailableLoad targetLoad = targetValueNumberFrame.getLoad(targetVN);
                                if (!load.equals(targetLoad)) {
                                    continue;
                                }
                                if (DEBUG) {
                                    System.out.println("** Copy vn derefs for " + load + " from " + targetVN + " --> " + blockVN);

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                    try {
                        ValueNumberDataflow vnaDataflow = getClassContext().getValueNumberDataflow(getMethod());
                        IsNullValueDataflow invDataflow = getClassContext().getIsNullValueDataflow(getMethod());
                        ValueNumberFrame vFrame = vnaDataflow.getAnalysis().getFactAtPC(vnaDataflow.getCFG(), getPC());
                        IsNullValueFrame iFrame = invDataflow.getAnalysis().getFactAtPC(invDataflow.getCFG(), getPC());
                        AvailableLoad l = new AvailableLoad(f);
                        ValueNumber[] availableLoads = vFrame.getAvailableLoad(l);
                        if (availableLoads != null && iFrame.isTrackValueNumbers()) {
                            for (ValueNumber v : availableLoads) {
                                IsNullValue knownValue = iFrame.getKnownValue(v);
                                if (knownValue == null) {

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Related Classes of edu.umd.cs.findbugs.ba.vna.AvailableLoad

edu.umd.cs.findbugs.ba.deref.UnconditionalValueDerefAnalysis

edu.umd.cs.findbugs.ba.npe.IsNullValueAnalysis

edu.umd.cs.findbugs.ba.npe.IsNullValueFrameModelingVisitor

edu.umd.cs.findbugs.detect.UnreadFields

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