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
33namespace JSC {
34
35inline bool operandIsLocal(int operand)
36{
37    return operand < 0;
38}
39
40inline bool operandIsArgument(int operand)
41{
42    return operand >= 0;
43}
44
45
46class VirtualRegister {
47public:
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
72private:
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
84COMPILE_ASSERT(sizeof(VirtualRegister) == sizeof(int), VirtualRegister_is_32bit);
85
86inline VirtualRegister virtualRegisterForLocal(int local)
87{
88    return VirtualRegister(VirtualRegister::localToOperand(local));
89}
90
91inline VirtualRegister virtualRegisterForArgument(int argument, int offset = 0)
92{
93    return VirtualRegister(VirtualRegister::argumentToOperand(argument) + offset);
94}
95
96} // namespace JSC
97
98namespace WTF {
99
100inline void printInternal(PrintStream& out, JSC::VirtualRegister value)
101{
102    out.print(value.offset());
103}
104
105} // namespace WTF
106
107#endif // VirtualRegister_h
108