weex_core/Source/include/JavaScriptCore/dfg/DFGValueStrength.h

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
#pragma once

#if ENABLE(DFG_JIT)

#include <wtf/PrintStream.h>

namespace JSC { namespace DFG {

enum ValueStrength {
    // The value has been used for optimization and it arose through inference. We don't want the
    // fact that we optimized the code to result in the GC keeping this value alive unnecessarily,
    // so we'd rather kill the code and recompile than keep the object alive longer.
    WeakValue,
    
    // The code will keep this value alive. This is true of constants that were present in the
    // source. String constants tend to be strong.
    StrongValue
};

inline ValueStrength merge(ValueStrength a, ValueStrength b)
{
    switch (a) {
    case WeakValue:
        return b;
    case StrongValue:
        return StrongValue;
    }
    RELEASE_ASSERT_NOT_REACHED();

    return WeakValue;
}

} } // namespace JSC::DFG

namespace WTF {

void printInternal(PrintStream&, JSC::DFG::ValueStrength);

} // namespace WTF

#endif // ENABLE(DFG_JIT)