1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef frontend_BytecodeControlStructures_h
#define frontend_BytecodeControlStructures_h
#include "mozilla/Assertions.h" // MOZ_ASSERT
#include "mozilla/Maybe.h" // mozilla::Maybe
#include <stdint.h> // int32_t, uint32_t
#include "ds/Nestable.h" // Nestable
#include "frontend/BytecodeOffset.h" // BytecodeOffset
#include "frontend/JumpList.h" // JumpList, JumpTarget
#include "frontend/ParserAtom.h" // TaggedParserAtomIndex
#include "frontend/SharedContext.h" // StatementKind, StatementKindIsLoop, StatementKindIsUnlabeledBreakTarget
#include "frontend/TDZCheckCache.h" // TDZCheckCache
#include "vm/StencilEnums.h" // TryNoteKind
namespace js {
namespace frontend {
struct BytecodeEmitter;
class EmitterScope;
class NestableControl : public Nestable<NestableControl> {
StatementKind kind_;
// The innermost scope when this was pushed.
EmitterScope* emitterScope_;
protected:
NestableControl(BytecodeEmitter* bce, StatementKind kind);
public:
using Nestable<NestableControl>::enclosing;
using Nestable<NestableControl>::findNearest;
StatementKind kind() const { return kind_; }
EmitterScope* emitterScope() const { return emitterScope_; }
template <typename T>
bool is() const;
template <typename T>
T& as() {
MOZ_ASSERT(this->is<T>());
return static_cast<T&>(*this);
}
};
class BreakableControl : public NestableControl {
public:
// Offset of the last break.
JumpList breaks;
BreakableControl(BytecodeEmitter* bce, StatementKind kind);
[[nodiscard]] bool patchBreaks(BytecodeEmitter* bce);
};
template <>
inline bool NestableControl::is<BreakableControl>() const {
return StatementKindIsUnlabeledBreakTarget(kind_) ||
kind_ == StatementKind::Label;
}
class LabelControl : public BreakableControl {
TaggedParserAtomIndex label_;
// The code offset when this was pushed. Used for effectfulness checking.
BytecodeOffset startOffset_;
public:
LabelControl(BytecodeEmitter* bce, TaggedParserAtomIndex label,
BytecodeOffset startOffset);
TaggedParserAtomIndex label() const { return label_; }
BytecodeOffset startOffset() const { return startOffset_; }
};
template <>
inline bool NestableControl::is<LabelControl>() const {
return kind_ == StatementKind::Label;
}
class LoopControl : public BreakableControl {
// Loops' children are emitted in dominance order, so they can always
// have a TDZCheckCache.
TDZCheckCache tdzCache_;
// Here's the basic structure of a loop:
//
// head:
// JSOp::LoopHead
// {loop condition/body}
//
// continueTarget:
// {loop update if present}
//
// # Loop end, backward jump
// JSOp::Goto/JSOp::JumpIfTrue head
//
// breakTarget:
// The bytecode offset of JSOp::LoopHead.
JumpTarget head_;
// Stack depth when this loop was pushed on the control stack.
int32_t stackDepth_;
// The loop nesting depth. Used as a hint to Ion.
uint32_t loopDepth_;
public:
// Offset of the last continue in the loop.
JumpList continues;
LoopControl(BytecodeEmitter* bce, StatementKind loopKind);
BytecodeOffset headOffset() const { return head_.offset; }
[[nodiscard]] bool emitContinueTarget(BytecodeEmitter* bce);
// `nextPos` is the offset in the source code for the character that
// corresponds to the next instruction after JSOp::LoopHead.
// Can be Nothing() if not available.
[[nodiscard]] bool emitLoopHead(BytecodeEmitter* bce,
const mozilla::Maybe<uint32_t>& nextPos);
[[nodiscard]] bool emitLoopEnd(BytecodeEmitter* bce, JSOp op,
TryNoteKind tryNoteKind);
};
template <>
inline bool NestableControl::is<LoopControl>() const {
return StatementKindIsLoop(kind_);
}
enum class NonLocalExitKind { Continue, Break, Return };
class TryFinallyContinuation {
public:
TryFinallyContinuation(NestableControl* target, NonLocalExitKind kind)
: target_(target), kind_(kind) {}
NestableControl* target_;
NonLocalExitKind kind_;
};
class TryFinallyControl : public NestableControl {
bool emittingSubroutine_ = false;
public:
// Offset of the last jump to this `finally`.
JumpList finallyJumps_;
js::Vector<TryFinallyContinuation, 4, SystemAllocPolicy> continuations_;
TryFinallyControl(BytecodeEmitter* bce, StatementKind kind);
void setEmittingSubroutine() { emittingSubroutine_ = true; }
bool emittingSubroutine() const { return emittingSubroutine_; }
enum SpecialContinuations { Fallthrough, Count };
bool allocateContinuation(NestableControl* target, NonLocalExitKind kind,
uint32_t* idx);
bool emitContinuations(BytecodeEmitter* bce);
};
template <>
inline bool NestableControl::is<TryFinallyControl>() const {
return kind_ == StatementKind::Try || kind_ == StatementKind::Finally;
}
class NonLocalExitControl {
BytecodeEmitter* bce_;
const uint32_t savedScopeNoteIndex_;
const int savedDepth_;
uint32_t openScopeNoteIndex_;
NonLocalExitKind kind_;
// The offset of a `JSOp::SetRval` that can be rewritten as a
// `JSOp::Return` if we don't generate any code for this
// NonLocalExitControl.
BytecodeOffset setRvalOffset_ = BytecodeOffset::invalidOffset();
[[nodiscard]] bool leaveScope(EmitterScope* es);
public:
NonLocalExitControl(const NonLocalExitControl&) = delete;
NonLocalExitControl(BytecodeEmitter* bce, NonLocalExitKind kind);
~NonLocalExitControl();
[[nodiscard]] bool emitNonLocalJump(NestableControl* target,
NestableControl* startingAfter = nullptr);
[[nodiscard]] bool emitReturn(BytecodeOffset setRvalOffset);
};
} /* namespace frontend */
} /* namespace js */
#endif /* frontend_BytecodeControlStructures_h */
|
