+inline bool operandIsLocal(int operand)
+{
+ return operand < 0;
+}
+
+inline bool operandIsArgument(int operand)
+{
+ return operand >= 0;
+}
+
+
+class VirtualRegister {
+public:
+ friend VirtualRegister virtualRegisterForLocal(int);
+ friend VirtualRegister virtualRegisterForArgument(int, int);
+
+ VirtualRegister()
+ : m_virtualRegister(s_invalidVirtualRegister)
+ { }
+
+ explicit VirtualRegister(int virtualRegister)
+ : m_virtualRegister(virtualRegister)
+ { }
+
+ bool isValid() const { return (m_virtualRegister != s_invalidVirtualRegister); }
+ bool isLocal() const { return operandIsLocal(m_virtualRegister); }
+ bool isArgument() const { return operandIsArgument(m_virtualRegister); }
+ bool isConstant() const { return m_virtualRegister >= s_firstConstantRegisterIndex; }
+ int toLocal() const { ASSERT(isLocal()); return operandToLocal(m_virtualRegister); }
+ int toArgument() const { ASSERT(isArgument()); return operandToArgument(m_virtualRegister); }
+ int toConstantIndex() const { ASSERT(isConstant()); return m_virtualRegister - s_firstConstantRegisterIndex; }
+ int offset() const { return m_virtualRegister; }
+ int offsetInBytes() const { return m_virtualRegister * sizeof(Register); }
+
+ bool operator==(const VirtualRegister other) const { return m_virtualRegister == other.m_virtualRegister; }
+ bool operator!=(const VirtualRegister other) const { return m_virtualRegister != other.m_virtualRegister; }
+
+private:
+ static const int s_invalidVirtualRegister = 0x3fffffff;
+ static const int s_firstConstantRegisterIndex = 0x40000000;
+
+ static int localToOperand(int local) { return -1 - local; }
+ static int operandToLocal(int operand) { return -1 - operand; }
+ static int operandToArgument(int operand) { return operand - CallFrame::thisArgumentOffset(); }
+ static int argumentToOperand(int argument) { return argument + CallFrame::thisArgumentOffset(); }
+
+ int m_virtualRegister;
+};
+