weex_core/Source/include/JavaScriptCore/heap/ConstraintVolatility.h

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 * Copyright (C) 2017 Apple Inc. All rights reserved.
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#pragma once

#include <wtf/PrintStream.h>

namespace JSC {

enum class ConstraintVolatility : uint8_t {
    // The constraint needs to be validated, but it is unlikely to ever produce information.
    // It's best to run it at the bitter end.
    SeldomGreyed,
    
    // FIXME: We could introduce a new kind of volatility called GreyedByResumption, which
    // would mean running all of the times that GreyedByExecution runs except as a root in a
    // full GC.
    // https://bugs.webkit.org/show_bug.cgi?id=166830
    
    // The constraint needs to be reevaluated anytime the mutator runs: so at GC start and
    // whenever the GC resuspends after a resumption. This is almost always something that
    // you'd call a "root" in a traditional GC.
    GreyedByExecution,
    
    // The constraint needs to be reevaluated any time any object is marked and anytime the
    // mutator resumes.
    GreyedByMarking
};
    
} // namespace JSC

namespace WTF {

inline void printInternal(PrintStream& out, JSC::ConstraintVolatility volatility)
{
    switch (volatility) {
    case JSC::ConstraintVolatility::SeldomGreyed:
        out.print("SeldomGreyed");
        return;
    case JSC::ConstraintVolatility::GreyedByExecution:
        out.print("GreyedByExecuction");
        return;
    case JSC::ConstraintVolatility::GreyedByMarking:
        out.print("GreyedByMarking");
        return;
    }
    RELEASE_ASSERT_NOT_REACHED();
}

} // namespace WTF