1 /*

     2  * Copyright (C) 2008 Apple Inc. All rights reserved.

     3  *

     4  * Redistribution and use in source and binary forms, with or without

     5  * modification, are permitted provided that the following conditions

     6  * are met:

     7  *

     8  * 1.  Redistributions of source code must retain the above copyright

     9  *     notice, this list of conditions and the following disclaimer.

    10  * 2.  Redistributions in binary form must reproduce the above copyright

    11  *     notice, this list of conditions and the following disclaimer in the

    12  *     documentation and/or other materials provided with the distribution.

    13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of

    14  *     its contributors may be used to endorse or promote products derived

    15  *     from this software without specific prior written permission.

    16  *

    17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY

    18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

    19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

    20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

    21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

    22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

    23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

    24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

    25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

    26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    27  */

    28 

    29 #ifndef Label_h

    30 #define Label_h

    31 

    32 #include "CodeBlock.h"

    33 #include "Instruction.h"

    34 #include <wtf/Assertions.h>

    35 #include <wtf/Vector.h>

    36 #include <limits.h>

    37 

    38 namespace JSC {

    39 

    40     class Label {

    41     public:

    42         explicit Label(CodeBlock* codeBlock)

    43             : m_refCount(0)

    44             , m_location(invalidLocation)

    45             , m_codeBlock(codeBlock)

    46         {

    47         }

    48 

    49         void setLocation(unsigned location)

    50         {

    51             m_location = location;

    52 

    53             unsigned size = m_unresolvedJumps.size();

    54             for (unsigned i = 0; i < size; ++i)

    55                 m_codeBlock->instructions()[m_unresolvedJumps[i].second].u.operand = m_location - m_unresolvedJumps[i].first;

    56         }

    57 

    58         int bind(int opcode, int offset) const

    59         {

    60             if (m_location == invalidLocation) {

    61                 m_unresolvedJumps.append(std::make_pair(opcode, offset));

    62                 return 0;

    63             }

    64             return m_location - opcode;

    65         }

    66 

    67         void ref() { ++m_refCount; }

    68         void deref()

    69         {

    70             --m_refCount;

    71             ASSERT(m_refCount >= 0);

    72         }

    73         int refCount() const { return m_refCount; }

    74 

    75         bool isForward() const { return m_location == invalidLocation; }

    76 

    77     private:

    78         typedef Vector<std::pair<int, int>, 8> JumpVector;

    79 

    80         static const unsigned invalidLocation = UINT_MAX;

    81 

    82         int m_refCount;

    83         unsigned m_location;

    84         CodeBlock* m_codeBlock;

    85         mutable JumpVector m_unresolvedJumps;

    86     };

    87 

    88 } // namespace JSC

    89 

    90 #endif // Label_h