JavaScriptCore/bytecompiler/Label.h

   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