Source/JavaScriptCore/runtime/NarrowingNumberPredictionFuzzerAgent.cpp

/*
 * Copyright (C) 2019-2023 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
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 *
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
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#include "config.h"
#include "NarrowingNumberPredictionFuzzerAgent.h"

#include "CodeBlock.h"
#include <wtf/TZoneMallocInlines.h>

namespace JSC {

WTF_MAKE_TZONE_ALLOCATED_IMPL(NarrowingNumberPredictionFuzzerAgent);

NarrowingNumberPredictionFuzzerAgent::NarrowingNumberPredictionFuzzerAgent(VM& vm)
    : NumberPredictionFuzzerAgent(vm)
{
}

SpeculatedType NarrowingNumberPredictionFuzzerAgent::getPrediction(CodeBlock* codeBlock, const CodeOrigin& codeOrigin, SpeculatedType original)
{
    Locker locker { m_lock };

    if (!(original && speculationChecked(original, SpecBytecodeNumber)))
        return original;

    Vector<SpeculatedType> numberTypesThatCouldBePartOfSpeculation;
    for (auto numberType : bytecodeNumberTypes()) {
        if (numberType & original)
            numberTypesThatCouldBePartOfSpeculation.append(numberType);
    }

    unsigned numberOfTypesToKeep = m_random.getUint32(numberTypesThatCouldBePartOfSpeculation.size()) + 1;
    if (numberOfTypesToKeep == numberTypesThatCouldBePartOfSpeculation.size())
        return original;

    SpeculatedType generated = SpecNone;
    for (unsigned i = 0; i < numberOfTypesToKeep; i++) {
        unsigned indexOfTypeToKeep = m_random.getUint32(numberTypesThatCouldBePartOfSpeculation.size());
        mergeSpeculation(generated, numberTypesThatCouldBePartOfSpeculation[indexOfTypeToKeep]);
        numberTypesThatCouldBePartOfSpeculation.remove(indexOfTypeToKeep);
    }

    if (Options::dumpFuzzerAgentPredictions())
        dataLogLn("NarrowingNumberPredictionFuzzerAgent::getPrediction name:(", codeBlock->inferredName(), "#", codeBlock->hashAsStringIfPossible(), "),bytecodeIndex:(", codeOrigin.bytecodeIndex(), "),original:(", SpeculationDump(original), "),generated:(", SpeculationDump(generated), ")");

    return generated;
}

} // namespace JSC