bytecode/VirtualRegister.h

   1 /*
   2  * Copyright (C) 2011 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  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef VirtualRegister_h
  27 #define VirtualRegister_h
  28
  29 #include "CallFrame.h"
  30
  31 #include <wtf/PrintStream.h>
  32
  33 namespace JSC {
  34
  35 inline bool operandIsLocal(int operand)
  36 {
  37     return operand < 0;
  38 }
  39
  40 inline bool operandIsArgument(int operand)
  41 {
  42     return operand >= 0;
  43 }
  44
  45
  46 class VirtualRegister {
  47 public:
  48     friend VirtualRegister virtualRegisterForLocal(int);
  49     friend VirtualRegister virtualRegisterForArgument(int, int);
  50
  51     VirtualRegister()
  52         : m_virtualRegister(s_invalidVirtualRegister)
  53     { }
  54
  55     explicit VirtualRegister(int virtualRegister)
  56         : m_virtualRegister(virtualRegister)
  57     { }
  58
  59     bool isValid() const { return (m_virtualRegister != s_invalidVirtualRegister); }
  60     bool isLocal() const { return operandIsLocal(m_virtualRegister); }
  61     bool isArgument() const { return operandIsArgument(m_virtualRegister); }
  62     bool isConstant() const { return m_virtualRegister >= s_firstConstantRegisterIndex; }
  63     int toLocal() const { ASSERT(isLocal()); return operandToLocal(m_virtualRegister); }
  64     int toArgument() const { ASSERT(isArgument()); return operandToArgument(m_virtualRegister); }
  65     int toConstantIndex() const { ASSERT(isConstant()); return m_virtualRegister - s_firstConstantRegisterIndex; }
  66     int offset() const { return m_virtualRegister; }
  67     int offsetInBytes() const { return m_virtualRegister * sizeof(Register); }
  68
  69     bool operator==(const VirtualRegister other) const { return m_virtualRegister == other.m_virtualRegister; }
  70     bool operator!=(const VirtualRegister other) const { return m_virtualRegister != other.m_virtualRegister; }
  71
  72 private:
  73     static const int s_invalidVirtualRegister = 0x3fffffff;
  74     static const int s_firstConstantRegisterIndex = 0x40000000;
  75
  76     static int localToOperand(int local) { return -1 - local; }
  77     static int operandToLocal(int operand) { return -1 - operand; }
  78     static int operandToArgument(int operand) { return operand - CallFrame::thisArgumentOffset(); }
  79     static int argumentToOperand(int argument) { return argument + CallFrame::thisArgumentOffset(); }
  80
  81     int m_virtualRegister;
  82 };
  83
  84 COMPILE_ASSERT(sizeof(VirtualRegister) == sizeof(int), VirtualRegister_is_32bit);
  85
  86 inline VirtualRegister virtualRegisterForLocal(int local)
  87 {
  88     return VirtualRegister(VirtualRegister::localToOperand(local));
  89 }
  90
  91 inline VirtualRegister virtualRegisterForArgument(int argument, int offset = 0)
  92 {
  93     return VirtualRegister(VirtualRegister::argumentToOperand(argument) + offset);
  94 }
  95
  96 } // namespace JSC
  97
  98 namespace WTF {
  99
 100 inline void printInternal(PrintStream& out, JSC::VirtualRegister value)
 101 {
 102     out.print(value.offset());
 103 }
 104
 105 } // namespace WTF
 106
 107 #endif // VirtualRegister_h