1// Copyright 2012 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_ARM_FRAMES_ARM_H_
6#define V8_ARM_FRAMES_ARM_H_
7
8namespace v8 {
9namespace internal {
10
11
12// The ARM ABI does not specify the usage of register r9, which may be reserved
13// as the static base or thread register on some platforms, in which case we
14// leave it alone. Adjust the value of kR9Available accordingly:
15const int kR9Available = 1;  // 1 if available to us, 0 if reserved
16
17
18// Register list in load/store instructions
19// Note that the bit values must match those used in actual instruction encoding
20const int kNumRegs = 16;
21
22
23// Caller-saved/arguments registers
24const RegList kJSCallerSaved =
25  1 << 0 |  // r0 a1
26  1 << 1 |  // r1 a2
27  1 << 2 |  // r2 a3
28  1 << 3;   // r3 a4
29
30const int kNumJSCallerSaved = 4;
31
32// Return the code of the n-th caller-saved register available to JavaScript
33// e.g. JSCallerSavedReg(0) returns r0.code() == 0
34int JSCallerSavedCode(int n);
35
36
37// Callee-saved registers preserved when switching from C to JavaScript
38const RegList kCalleeSaved =
39  1 <<  4 |  //  r4 v1
40  1 <<  5 |  //  r5 v2
41  1 <<  6 |  //  r6 v3
42  1 <<  7 |  //  r7 v4 (cp in JavaScript code)
43  1 <<  8 |  //  r8 v5 (pp in JavaScript code)
44  kR9Available <<  9 |  //  r9 v6
45  1 << 10 |  // r10 v7
46  1 << 11;   // r11 v8 (fp in JavaScript code)
47
48// When calling into C++ (only for C++ calls that can't cause a GC).
49// The call code will take care of lr, fp, etc.
50const RegList kCallerSaved =
51  1 <<  0 |  // r0
52  1 <<  1 |  // r1
53  1 <<  2 |  // r2
54  1 <<  3 |  // r3
55  1 <<  9;   // r9
56
57
58const int kNumCalleeSaved = 7 + kR9Available;
59
60// Double registers d8 to d15 are callee-saved.
61const int kNumDoubleCalleeSaved = 8;
62
63
64// Number of registers for which space is reserved in safepoints. Must be a
65// multiple of 8.
66// TODO(regis): Only 8 registers may actually be sufficient. Revisit.
67const int kNumSafepointRegisters = 16;
68
69// The embedded constant pool pointer (r8/pp) is not included in the safepoint
70// since it is not tagged.  This register is preserved in the stack frame where
71// its value will be updated if GC code movement occurs.  Including it in the
72// safepoint (where it will not be relocated) would cause a stale value to be
73// restored.
74const RegList kConstantPointerRegMask =
75    FLAG_enable_embedded_constant_pool ? (1 << 8) : 0;
76const int kNumConstantPoolPointerReg =
77    FLAG_enable_embedded_constant_pool ? 1 : 0;
78
79// Define the list of registers actually saved at safepoints.
80// Note that the number of saved registers may be smaller than the reserved
81// space, i.e. kNumSafepointSavedRegisters <= kNumSafepointRegisters.
82const RegList kSafepointSavedRegisters =
83    kJSCallerSaved | (kCalleeSaved & ~kConstantPointerRegMask);
84const int kNumSafepointSavedRegisters =
85    kNumJSCallerSaved + kNumCalleeSaved - kNumConstantPoolPointerReg;
86
87// ----------------------------------------------------
88
89
90class EntryFrameConstants : public AllStatic {
91 public:
92  static const int kCallerFPOffset =
93      -(StandardFrameConstants::kFixedFrameSizeFromFp + kPointerSize);
94};
95
96class ExitFrameConstants : public TypedFrameConstants {
97 public:
98  static const int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
99  static const int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
100  DEFINE_TYPED_FRAME_SIZES(2);
101
102  // The caller fields are below the frame pointer on the stack.
103  static const int kCallerFPOffset = 0 * kPointerSize;
104  // The calling JS function is below FP.
105  static const int kCallerPCOffset = 1 * kPointerSize;
106
107  // FP-relative displacement of the caller's SP.  It points just
108  // below the saved PC.
109  static const int kCallerSPDisplacement = 2 * kPointerSize;
110};
111
112
113class JavaScriptFrameConstants : public AllStatic {
114 public:
115  // FP-relative.
116  static const int kLocal0Offset = StandardFrameConstants::kExpressionsOffset;
117  static const int kLastParameterOffset = +2 * kPointerSize;
118  static const int kFunctionOffset = StandardFrameConstants::kFunctionOffset;
119
120  // Caller SP-relative.
121  static const int kParam0Offset   = -2 * kPointerSize;
122  static const int kReceiverOffset = -1 * kPointerSize;
123};
124
125
126}  // namespace internal
127}  // namespace v8
128
129#endif  // V8_ARM_FRAMES_ARM_H_
130