summaryrefslogtreecommitdiffstats
path: root/js/src/frontend/BytecodeEmitter.h
blob: 32668a34caf6562184ec8a36addac27ffbc19b36 (plain)
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
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * 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/. */

/* JS bytecode generation. */

#ifndef frontend_BytecodeEmitter_h
#define frontend_BytecodeEmitter_h

#include "jscntxt.h"
#include "jsopcode.h"
#include "jsscript.h"

#include "ds/InlineTable.h"
#include "frontend/Parser.h"
#include "frontend/SharedContext.h"
#include "frontend/SourceNotes.h"
#include "vm/Interpreter.h"

namespace js {
namespace frontend {

class FullParseHandler;
class ObjectBox;
class ParseNode;
template <typename ParseHandler> class Parser;
class SharedContext;
class TokenStream;

class CGConstList {
    Vector<Value> list;
  public:
    explicit CGConstList(ExclusiveContext* cx) : list(cx) {}
    MOZ_MUST_USE bool append(const Value& v) {
        MOZ_ASSERT_IF(v.isString(), v.toString()->isAtom());
        return list.append(v);
    }
    size_t length() const { return list.length(); }
    void finish(ConstArray* array);
};

struct CGObjectList {
    uint32_t            length;     /* number of emitted so far objects */
    ObjectBox*          lastbox;   /* last emitted object */

    CGObjectList() : length(0), lastbox(nullptr) {}

    unsigned add(ObjectBox* objbox);
    unsigned indexOf(JSObject* obj);
    void finish(ObjectArray* array);
    ObjectBox* find(uint32_t index);
};

struct MOZ_STACK_CLASS CGScopeList {
    Rooted<GCVector<Scope*>> vector;

    explicit CGScopeList(ExclusiveContext* cx)
      : vector(cx, GCVector<Scope*>(cx))
    { }

    bool append(Scope* scope) { return vector.append(scope); }
    uint32_t length() const { return vector.length(); }
    void finish(ScopeArray* array);
};

struct CGTryNoteList {
    Vector<JSTryNote> list;
    explicit CGTryNoteList(ExclusiveContext* cx) : list(cx) {}

    MOZ_MUST_USE bool append(JSTryNoteKind kind, uint32_t stackDepth, size_t start, size_t end);
    size_t length() const { return list.length(); }
    void finish(TryNoteArray* array);
};

struct CGScopeNote : public ScopeNote
{
    // The end offset. Used to compute the length; may need adjusting first if
    // in the prologue.
    uint32_t end;

    // Is the start offset in the prologue?
    bool startInPrologue;

    // Is the end offset in the prologue?
    bool endInPrologue;
};

struct CGScopeNoteList {
    Vector<CGScopeNote> list;
    explicit CGScopeNoteList(ExclusiveContext* cx) : list(cx) {}

    MOZ_MUST_USE bool append(uint32_t scopeIndex, uint32_t offset, bool inPrologue,
                             uint32_t parent);
    void recordEnd(uint32_t index, uint32_t offset, bool inPrologue);
    size_t length() const { return list.length(); }
    void finish(ScopeNoteArray* array, uint32_t prologueLength);
};

struct CGYieldOffsetList {
    Vector<uint32_t> list;
    uint32_t numYields;
    uint32_t numAwaits;
    explicit CGYieldOffsetList(ExclusiveContext* cx) : list(cx), numYields(0), numAwaits(0) {}

    MOZ_MUST_USE bool append(uint32_t offset) { return list.append(offset); }
    size_t length() const { return list.length(); }
    void finish(YieldOffsetArray& array, uint32_t prologueLength);
};

// Use zero inline elements because these go on the stack and affect how many
// nested functions are possible.
typedef Vector<jsbytecode, 0> BytecodeVector;
typedef Vector<jssrcnote, 0> SrcNotesVector;

// Linked list of jump instructions that need to be patched. The linked list is
// stored in the bytes of the incomplete bytecode that will be patched, so no
// extra memory is needed, and patching the instructions destroys the list.
//
// Example:
//
//     JumpList brList;
//     if (!emitJump(JSOP_IFEQ, &brList))
//         return false;
//     ...
//     JumpTarget label;
//     if (!emitJumpTarget(&label))
//         return false;
//     ...
//     if (!emitJump(JSOP_GOTO, &brList))
//         return false;
//     ...
//     patchJumpsToTarget(brList, label);
//
//                 +-> -1
//                 |
//                 |
//    ifeq ..   <+ +                +-+   ifeq ..
//    ..         |                  |     ..
//  label:       |                  +-> label:
//    jumptarget |                  |     jumptarget
//    ..         |                  |     ..
//    goto .. <+ +                  +-+   goto .. <+
//             |                                   |
//             |                                   |
//             +                                   +
//           brList                              brList
//
//       |                                  ^
//       +------- patchJumpsToTarget -------+
//

// Offset of a jump target instruction, used for patching jump instructions.
struct JumpTarget {
    ptrdiff_t offset;
};

struct JumpList {
    // -1 is used to mark the end of jump lists.
    JumpList() : offset(-1) {}
    ptrdiff_t offset;

    // Add a jump instruction to the list.
    void push(jsbytecode* code, ptrdiff_t jumpOffset);

    // Patch all jump instructions in this list to jump to `target`.  This
    // clobbers the list.
    void patchAll(jsbytecode* code, JumpTarget target);
};

struct MOZ_STACK_CLASS BytecodeEmitter
{
    class TDZCheckCache;
    class NestableControl;
    class EmitterScope;

    SharedContext* const sc;      /* context shared between parsing and bytecode generation */

    ExclusiveContext* const cx;

    BytecodeEmitter* const parent;  /* enclosing function or global context */

    Rooted<JSScript*> script;       /* the JSScript we're ultimately producing */

    Rooted<LazyScript*> lazyScript; /* the lazy script if mode is LazyFunction,
                                        nullptr otherwise. */

    struct EmitSection {
        BytecodeVector code;        /* bytecode */
        SrcNotesVector notes;       /* source notes, see below */
        ptrdiff_t   lastNoteOffset; /* code offset for last source note */
        uint32_t    currentLine;    /* line number for tree-based srcnote gen */
        uint32_t    lastColumn;     /* zero-based column index on currentLine of
                                       last SRC_COLSPAN-annotated opcode */
        JumpTarget lastTarget;      // Last jump target emitted.

        EmitSection(ExclusiveContext* cx, uint32_t lineNum)
          : code(cx), notes(cx), lastNoteOffset(0), currentLine(lineNum), lastColumn(0),
            lastTarget{ -1 - ptrdiff_t(JSOP_JUMPTARGET_LENGTH) }
        {}
    };
    EmitSection prologue, main, *current;

    Parser<FullParseHandler>* const parser;

    PooledMapPtr<AtomIndexMap> atomIndices; /* literals indexed for mapping */
    unsigned        firstLine;      /* first line, for JSScript::initFromEmitter */

    uint32_t        maxFixedSlots;  /* maximum number of fixed frame slots so far */
    uint32_t        maxStackDepth;  /* maximum number of expression stack slots so far */

    int32_t         stackDepth;     /* current stack depth in script frame */

    uint32_t        arrayCompDepth; /* stack depth of array in comprehension */

    unsigned        emitLevel;      /* emitTree recursion level */

    uint32_t        bodyScopeIndex; /* index into scopeList of the body scope */

    EmitterScope*    varEmitterScope;
    NestableControl* innermostNestableControl;
    EmitterScope*    innermostEmitterScope;
    TDZCheckCache*   innermostTDZCheckCache;

    CGConstList      constList;      /* constants to be included with the script */
    CGObjectList     objectList;     /* list of emitted objects */
    CGScopeList      scopeList;      /* list of emitted scopes */
    CGTryNoteList    tryNoteList;    /* list of emitted try notes */
    CGScopeNoteList  scopeNoteList;  /* list of emitted block scope notes */

    /*
     * For each yield op, map the yield index (stored as bytecode operand) to
     * the offset of the next op.
     */
    CGYieldOffsetList yieldOffsetList;

    uint16_t        typesetCount;   /* Number of JOF_TYPESET opcodes generated */

    bool            hasSingletons:1;    /* script contains singleton initializer JSOP_OBJECT */

    bool            hasTryFinally:1;    /* script contains finally block */

    bool            emittingRunOnceLambda:1; /* true while emitting a lambda which is only
                                                expected to run once. */

    bool isRunOnceLambda();

    enum EmitterMode {
        Normal,

        /*
         * Emit JSOP_GETINTRINSIC instead of JSOP_GETNAME and assert that
         * JSOP_GETNAME and JSOP_*GNAME don't ever get emitted. See the comment
         * for the field |selfHostingMode| in Parser.h for details.
         */
        SelfHosting,

        /*
         * Check the static scope chain of the root function for resolving free
         * variable accesses in the script.
         */
        LazyFunction
    };

    const EmitterMode emitterMode;

    // The end location of a function body that is being emitted.
    uint32_t functionBodyEndPos;
    // Whether functionBodyEndPos was set.
    bool functionBodyEndPosSet;

    /*
     * Note that BytecodeEmitters are magic: they own the arena "top-of-stack"
     * space above their tempMark points. This means that you cannot alloc from
     * tempLifoAlloc and save the pointer beyond the next BytecodeEmitter
     * destruction.
     */
    BytecodeEmitter(BytecodeEmitter* parent, Parser<FullParseHandler>* parser, SharedContext* sc,
                    HandleScript script, Handle<LazyScript*> lazyScript, uint32_t lineNum,
                    EmitterMode emitterMode = Normal);

    // An alternate constructor that uses a TokenPos for the starting
    // line and that sets functionBodyEndPos as well.
    BytecodeEmitter(BytecodeEmitter* parent, Parser<FullParseHandler>* parser, SharedContext* sc,
                    HandleScript script, Handle<LazyScript*> lazyScript,
                    TokenPos bodyPosition, EmitterMode emitterMode = Normal);

    MOZ_MUST_USE bool init();

    template <typename Predicate /* (NestableControl*) -> bool */>
    NestableControl* findInnermostNestableControl(Predicate predicate) const;

    template <typename T>
    T* findInnermostNestableControl() const;

    template <typename T, typename Predicate /* (T*) -> bool */>
    T* findInnermostNestableControl(Predicate predicate) const;

    NameLocation lookupName(JSAtom* name);

    // To implement Annex B and the formal parameter defaults scope semantics
    // requires accessing names that would otherwise be shadowed. This method
    // returns the access location of a name that is known to be bound in a
    // target scope.
    mozilla::Maybe<NameLocation> locationOfNameBoundInScope(JSAtom* name, EmitterScope* target);

    // Get the location of a name known to be bound in the function scope,
    // starting at the source scope.
    mozilla::Maybe<NameLocation> locationOfNameBoundInFunctionScope(JSAtom* name,
                                                                    EmitterScope* source);

    mozilla::Maybe<NameLocation> locationOfNameBoundInFunctionScope(JSAtom* name) {
        return locationOfNameBoundInFunctionScope(name, innermostEmitterScope);
    }

    void setVarEmitterScope(EmitterScope* emitterScope) {
        MOZ_ASSERT(emitterScope);
        MOZ_ASSERT(!varEmitterScope);
        varEmitterScope = emitterScope;
    }

    Scope* bodyScope() const { return scopeList.vector[bodyScopeIndex]; }
    Scope* outermostScope() const { return scopeList.vector[0]; }
    Scope* innermostScope() const;

    MOZ_ALWAYS_INLINE
    MOZ_MUST_USE bool makeAtomIndex(JSAtom* atom, uint32_t* indexp) {
        MOZ_ASSERT(atomIndices);
        AtomIndexMap::AddPtr p = atomIndices->lookupForAdd(atom);
        if (p) {
            *indexp = p->value();
            return true;
        }

        uint32_t index = atomIndices->count();
        if (!atomIndices->add(p, atom, index))
            return false;

        *indexp = index;
        return true;
    }

    bool isInLoop();
    MOZ_MUST_USE bool checkSingletonContext();

    // Check whether our function is in a run-once context (a toplevel
    // run-one script or a run-once lambda).
    MOZ_MUST_USE bool checkRunOnceContext();

    bool needsImplicitThis();

    MOZ_MUST_USE bool maybeSetDisplayURL();
    MOZ_MUST_USE bool maybeSetSourceMap();
    void tellDebuggerAboutCompiledScript(ExclusiveContext* cx);

    inline TokenStream* tokenStream();

    BytecodeVector& code() const { return current->code; }
    jsbytecode* code(ptrdiff_t offset) const { return current->code.begin() + offset; }
    ptrdiff_t offset() const { return current->code.end() - current->code.begin(); }
    ptrdiff_t prologueOffset() const { return prologue.code.end() - prologue.code.begin(); }
    void switchToMain() { current = &main; }
    void switchToPrologue() { current = &prologue; }
    bool inPrologue() const { return current == &prologue; }

    SrcNotesVector& notes() const { return current->notes; }
    ptrdiff_t lastNoteOffset() const { return current->lastNoteOffset; }
    unsigned currentLine() const { return current->currentLine; }
    unsigned lastColumn() const { return current->lastColumn; }

    // Check if the last emitted opcode is a jump target.
    bool lastOpcodeIsJumpTarget() const {
        return offset() - current->lastTarget.offset == ptrdiff_t(JSOP_JUMPTARGET_LENGTH);
    }

    // JumpTarget should not be part of the emitted statement, as they can be
    // aliased by multiple statements. If we included the jump target as part of
    // the statement we might have issues where the enclosing statement might
    // not contain all the opcodes of the enclosed statements.
    ptrdiff_t lastNonJumpTargetOffset() const {
        return lastOpcodeIsJumpTarget() ? current->lastTarget.offset : offset();
    }

    void setFunctionBodyEndPos(TokenPos pos) {
        functionBodyEndPos = pos.end;
        functionBodyEndPosSet = true;
    }

    bool reportError(ParseNode* pn, unsigned errorNumber, ...);
    bool reportExtraWarning(ParseNode* pn, unsigned errorNumber, ...);
    bool reportStrictModeError(ParseNode* pn, unsigned errorNumber, ...);

    // If pn contains a useful expression, return true with *answer set to true.
    // If pn contains a useless expression, return true with *answer set to
    // false. Return false on error.
    //
    // The caller should initialize *answer to false and invoke this function on
    // an expression statement or similar subtree to decide whether the tree
    // could produce code that has any side effects.  For an expression
    // statement, we define useless code as code with no side effects, because
    // the main effect, the value left on the stack after the code executes,
    // will be discarded by a pop bytecode.
    MOZ_MUST_USE bool checkSideEffects(ParseNode* pn, bool* answer);

#ifdef DEBUG
    MOZ_MUST_USE bool checkStrictOrSloppy(JSOp op);
#endif

    // Append a new source note of the given type (and therefore size) to the
    // notes dynamic array, updating noteCount. Return the new note's index
    // within the array pointed at by current->notes as outparam.
    MOZ_MUST_USE bool newSrcNote(SrcNoteType type, unsigned* indexp = nullptr);
    MOZ_MUST_USE bool newSrcNote2(SrcNoteType type, ptrdiff_t offset, unsigned* indexp = nullptr);
    MOZ_MUST_USE bool newSrcNote3(SrcNoteType type, ptrdiff_t offset1, ptrdiff_t offset2,
                                  unsigned* indexp = nullptr);

    void copySrcNotes(jssrcnote* destination, uint32_t nsrcnotes);
    MOZ_MUST_USE bool setSrcNoteOffset(unsigned index, unsigned which, ptrdiff_t offset);

    // NB: this function can add at most one extra extended delta note.
    MOZ_MUST_USE bool addToSrcNoteDelta(jssrcnote* sn, ptrdiff_t delta);

    // Finish taking source notes in cx's notePool. If successful, the final
    // source note count is stored in the out outparam.
    MOZ_MUST_USE bool finishTakingSrcNotes(uint32_t* out);

    // Control whether emitTree emits a line number note.
    enum EmitLineNumberNote {
        EMIT_LINENOTE,
        SUPPRESS_LINENOTE
    };

    // Emit code for the tree rooted at pn.
    MOZ_MUST_USE bool emitTree(ParseNode* pn, EmitLineNumberNote emitLineNote = EMIT_LINENOTE);

    // Emit code for the tree rooted at pn with its own TDZ cache.
    MOZ_MUST_USE bool emitTreeInBranch(ParseNode* pn);

    // Emit global, eval, or module code for tree rooted at body. Always
    // encompasses the entire source.
    MOZ_MUST_USE bool emitScript(ParseNode* body);

    // Emit function code for the tree rooted at body.
    MOZ_MUST_USE bool emitFunctionScript(ParseNode* body);

    // If op is JOF_TYPESET (see the type barriers comment in TypeInference.h),
    // reserve a type set to store its result.
    void checkTypeSet(JSOp op);

    void updateDepth(ptrdiff_t target);
    MOZ_MUST_USE bool updateLineNumberNotes(uint32_t offset);
    MOZ_MUST_USE bool updateSourceCoordNotes(uint32_t offset);

    JSOp strictifySetNameOp(JSOp op);

    MOZ_MUST_USE bool emitCheck(ptrdiff_t delta, ptrdiff_t* offset);

    // Emit one bytecode.
    MOZ_MUST_USE bool emit1(JSOp op);

    // Emit two bytecodes, an opcode (op) with a byte of immediate operand
    // (op1).
    MOZ_MUST_USE bool emit2(JSOp op, uint8_t op1);

    // Emit three bytecodes, an opcode with two bytes of immediate operands.
    MOZ_MUST_USE bool emit3(JSOp op, jsbytecode op1, jsbytecode op2);

    // Helper to emit JSOP_DUPAT. The argument is the value's depth on the
    // JS stack, as measured from the top.
    MOZ_MUST_USE bool emitDupAt(unsigned slotFromTop);

    // Helper to emit JSOP_CHECKISOBJ.
    MOZ_MUST_USE bool emitCheckIsObj(CheckIsObjectKind kind);

    // Helper to emit JSOP_CHECKISCALLABLE.
    MOZ_MUST_USE bool emitCheckIsCallable(CheckIsCallableKind kind);

    // Emit a bytecode followed by an uint16 immediate operand stored in
    // big-endian order.
    MOZ_MUST_USE bool emitUint16Operand(JSOp op, uint32_t operand);

    // Emit a bytecode followed by an uint32 immediate operand.
    MOZ_MUST_USE bool emitUint32Operand(JSOp op, uint32_t operand);

    // Emit (1 + extra) bytecodes, for N bytes of op and its immediate operand.
    MOZ_MUST_USE bool emitN(JSOp op, size_t extra, ptrdiff_t* offset = nullptr);

    MOZ_MUST_USE bool emitNumberOp(double dval);

    MOZ_MUST_USE bool emitThisLiteral(ParseNode* pn);
    MOZ_MUST_USE bool emitGetFunctionThis(ParseNode* pn);
    MOZ_MUST_USE bool emitGetThisForSuperBase(ParseNode* pn);
    MOZ_MUST_USE bool emitSetThis(ParseNode* pn);
    MOZ_MUST_USE bool emitCheckDerivedClassConstructorReturn();

    // Handle jump opcodes and jump targets.
    MOZ_MUST_USE bool emitJumpTarget(JumpTarget* target);
    MOZ_MUST_USE bool emitJumpNoFallthrough(JSOp op, JumpList* jump);
    MOZ_MUST_USE bool emitJump(JSOp op, JumpList* jump);
    MOZ_MUST_USE bool emitBackwardJump(JSOp op, JumpTarget target, JumpList* jump,
                                       JumpTarget* fallthrough);
    void patchJumpsToTarget(JumpList jump, JumpTarget target);
    MOZ_MUST_USE bool emitJumpTargetAndPatch(JumpList jump);

    MOZ_MUST_USE bool emitCall(JSOp op, uint16_t argc, ParseNode* pn = nullptr);
    MOZ_MUST_USE bool emitCallIncDec(ParseNode* incDec);

    MOZ_MUST_USE bool emitLoopHead(ParseNode* nextpn, JumpTarget* top);
    MOZ_MUST_USE bool emitLoopEntry(ParseNode* nextpn, JumpList entryJump);

    MOZ_MUST_USE bool emitGoto(NestableControl* target, JumpList* jumplist,
                               SrcNoteType noteType = SRC_NULL);

    MOZ_MUST_USE bool emitIndex32(JSOp op, uint32_t index);
    MOZ_MUST_USE bool emitIndexOp(JSOp op, uint32_t index);

    MOZ_MUST_USE bool emitAtomOp(JSAtom* atom, JSOp op);
    MOZ_MUST_USE bool emitAtomOp(ParseNode* pn, JSOp op);

    MOZ_MUST_USE bool emitArrayLiteral(ParseNode* pn);
    MOZ_MUST_USE bool emitArray(ParseNode* pn, uint32_t count, JSOp op);
    MOZ_MUST_USE bool emitArrayComp(ParseNode* pn);

    MOZ_MUST_USE bool emitInternedScopeOp(uint32_t index, JSOp op);
    MOZ_MUST_USE bool emitInternedObjectOp(uint32_t index, JSOp op);
    MOZ_MUST_USE bool emitObjectOp(ObjectBox* objbox, JSOp op);
    MOZ_MUST_USE bool emitObjectPairOp(ObjectBox* objbox1, ObjectBox* objbox2, JSOp op);
    MOZ_MUST_USE bool emitRegExp(uint32_t index);

    MOZ_NEVER_INLINE MOZ_MUST_USE bool emitFunction(ParseNode* pn, bool needsProto = false);
    MOZ_NEVER_INLINE MOZ_MUST_USE bool emitObject(ParseNode* pn);

    MOZ_MUST_USE bool emitHoistedFunctionsInList(ParseNode* pn);

    MOZ_MUST_USE bool emitPropertyList(ParseNode* pn, MutableHandlePlainObject objp,
                                       PropListType type);

    // To catch accidental misuse, emitUint16Operand/emit3 assert that they are
    // not used to unconditionally emit JSOP_GETLOCAL. Variable access should
    // instead be emitted using EmitVarOp. In special cases, when the caller
    // definitely knows that a given local slot is unaliased, this function may be
    // used as a non-asserting version of emitUint16Operand.
    MOZ_MUST_USE bool emitLocalOp(JSOp op, uint32_t slot);

    MOZ_MUST_USE bool emitArgOp(JSOp op, uint16_t slot);
    MOZ_MUST_USE bool emitEnvCoordOp(JSOp op, EnvironmentCoordinate ec);

    MOZ_MUST_USE bool emitGetNameAtLocation(JSAtom* name, const NameLocation& loc,
                                            bool callContext = false);
    MOZ_MUST_USE bool emitGetName(JSAtom* name, bool callContext = false) {
        return emitGetNameAtLocation(name, lookupName(name), callContext);
    }
    MOZ_MUST_USE bool emitGetName(ParseNode* pn, bool callContext = false);

    template <typename RHSEmitter>
    MOZ_MUST_USE bool emitSetOrInitializeNameAtLocation(HandleAtom name, const NameLocation& loc,
                                                        RHSEmitter emitRhs, bool initialize);
    template <typename RHSEmitter>
    MOZ_MUST_USE bool emitSetOrInitializeName(HandleAtom name, RHSEmitter emitRhs,
                                              bool initialize)
    {
        return emitSetOrInitializeNameAtLocation(name, lookupName(name), emitRhs, initialize);
    }
    template <typename RHSEmitter>
    MOZ_MUST_USE bool emitSetName(ParseNode* pn, RHSEmitter emitRhs) {
        RootedAtom name(cx, pn->name());
        return emitSetName(name, emitRhs);
    }
    template <typename RHSEmitter>
    MOZ_MUST_USE bool emitSetName(HandleAtom name, RHSEmitter emitRhs) {
        return emitSetOrInitializeName(name, emitRhs, false);
    }
    template <typename RHSEmitter>
    MOZ_MUST_USE bool emitInitializeName(ParseNode* pn, RHSEmitter emitRhs) {
        RootedAtom name(cx, pn->name());
        return emitInitializeName(name, emitRhs);
    }
    template <typename RHSEmitter>
    MOZ_MUST_USE bool emitInitializeName(HandleAtom name, RHSEmitter emitRhs) {
        return emitSetOrInitializeName(name, emitRhs, true);
    }

    MOZ_MUST_USE bool emitTDZCheckIfNeeded(JSAtom* name, const NameLocation& loc);

    MOZ_MUST_USE bool emitNameIncDec(ParseNode* pn);

    MOZ_MUST_USE bool emitDeclarationList(ParseNode* decls);
    MOZ_MUST_USE bool emitSingleDeclaration(ParseNode* decls, ParseNode* decl,
                                            ParseNode* initializer);

    MOZ_MUST_USE bool emitNewInit(JSProtoKey key);
    MOZ_MUST_USE bool emitSingletonInitialiser(ParseNode* pn);

    MOZ_MUST_USE bool emitPrepareIteratorResult();
    MOZ_MUST_USE bool emitFinishIteratorResult(bool done);
    MOZ_MUST_USE bool iteratorResultShape(unsigned* shape);

    MOZ_MUST_USE bool emitYield(ParseNode* pn);
    MOZ_MUST_USE bool emitYieldOp(JSOp op);
    MOZ_MUST_USE bool emitYieldStar(ParseNode* iter, ParseNode* gen);

    MOZ_MUST_USE bool emitPropLHS(ParseNode* pn);
    MOZ_MUST_USE bool emitPropOp(ParseNode* pn, JSOp op);
    MOZ_MUST_USE bool emitPropIncDec(ParseNode* pn);

    MOZ_MUST_USE bool emitAsyncWrapperLambda(unsigned index, bool isArrow);
    MOZ_MUST_USE bool emitAsyncWrapper(unsigned index, bool needsHomeObject, bool isArrow);

    MOZ_MUST_USE bool emitComputedPropertyName(ParseNode* computedPropName);

    // Emit bytecode to put operands for a JSOP_GETELEM/CALLELEM/SETELEM/DELELEM
    // opcode onto the stack in the right order. In the case of SETELEM, the
    // value to be assigned must already be pushed.
    enum class EmitElemOption { Get, Set, Call, IncDec, CompoundAssign, Ref };
    MOZ_MUST_USE bool emitElemOperands(ParseNode* pn, EmitElemOption opts);

    MOZ_MUST_USE bool emitElemOpBase(JSOp op);
    MOZ_MUST_USE bool emitElemOp(ParseNode* pn, JSOp op);
    MOZ_MUST_USE bool emitElemIncDec(ParseNode* pn);

    MOZ_MUST_USE bool emitCatch(ParseNode* pn);
    MOZ_MUST_USE bool emitIf(ParseNode* pn);
    MOZ_MUST_USE bool emitWith(ParseNode* pn);

    MOZ_NEVER_INLINE MOZ_MUST_USE bool emitLabeledStatement(const LabeledStatement* pn);
    MOZ_NEVER_INLINE MOZ_MUST_USE bool emitLexicalScope(ParseNode* pn);
    MOZ_MUST_USE bool emitLexicalScopeBody(ParseNode* body,
                                           EmitLineNumberNote emitLineNote = EMIT_LINENOTE);
    MOZ_NEVER_INLINE MOZ_MUST_USE bool emitSwitch(ParseNode* pn);
    MOZ_NEVER_INLINE MOZ_MUST_USE bool emitTry(ParseNode* pn);

    enum DestructuringFlavor {
        // Destructuring into a declaration.
        DestructuringDeclaration,

        // Destructuring into a formal parameter, when the formal parameters
        // contain an expression that might be evaluated, and thus require
        // this destructuring to assign not into the innermost scope that
        // contains the function body's vars, but into its enclosing scope for
        // parameter expressions.
        DestructuringFormalParameterInVarScope,

        // Destructuring as part of an AssignmentExpression.
        DestructuringAssignment
    };

    // emitDestructuringLHSRef emits the lhs expression's reference.
    // If the lhs expression is object property |OBJ.prop|, it emits |OBJ|.
    // If it's object element |OBJ[ELEM]|, it emits |OBJ| and |ELEM|.
    // If there's nothing to evaluate for the reference, it emits nothing.
    // |emitted| parameter receives the number of values pushed onto the stack.
    MOZ_MUST_USE bool emitDestructuringLHSRef(ParseNode* target, size_t* emitted);

    // emitSetOrInitializeDestructuring assumes the lhs expression's reference
    // and the to-be-destructured value has been pushed on the stack.  It emits
    // code to destructure a single lhs expression (either a name or a compound
    // []/{} expression).
    MOZ_MUST_USE bool emitSetOrInitializeDestructuring(ParseNode* target, DestructuringFlavor flav);

    // emitDestructuringOps assumes the to-be-destructured value has been
    // pushed on the stack and emits code to destructure each part of a [] or
    // {} lhs expression.
    MOZ_MUST_USE bool emitDestructuringOps(ParseNode* pattern, DestructuringFlavor flav);
    MOZ_MUST_USE bool emitDestructuringOpsArray(ParseNode* pattern, DestructuringFlavor flav);
    MOZ_MUST_USE bool emitDestructuringOpsObject(ParseNode* pattern, DestructuringFlavor flav);

    typedef bool
    (*DestructuringDeclEmitter)(BytecodeEmitter* bce, ParseNode* pn);

    template <typename NameEmitter>
    MOZ_MUST_USE bool emitDestructuringDeclsWithEmitter(ParseNode* pattern, NameEmitter emitName);

    // Throw a TypeError if the value atop the stack isn't convertible to an
    // object, with no overall effect on the stack.
    MOZ_MUST_USE bool emitRequireObjectCoercible();

    // emitIterator expects the iterable to already be on the stack.
    // It will replace that stack value with the corresponding iterator
    MOZ_MUST_USE bool emitIterator();

    // Pops iterator from the top of the stack. Pushes the result of |.next()|
    // onto the stack.
    MOZ_MUST_USE bool emitIteratorNext(ParseNode* pn, bool allowSelfHosted = false);
    MOZ_MUST_USE bool emitIteratorClose(CompletionKind completionKind = CompletionKind::Normal,
                                        bool allowSelfHosted = false);

    template <typename InnerEmitter>
    MOZ_MUST_USE bool wrapWithDestructuringIteratorCloseTryNote(int32_t iterDepth,
                                                                InnerEmitter emitter);

    // Check if the value on top of the stack is "undefined". If so, replace
    // that value on the stack with the value defined by |defaultExpr|.
    // |pattern| is a lhs node of the default expression.  If it's an
    // identifier and |defaultExpr| is an anonymous function, |SetFunctionName|
    // is called at compile time.
    MOZ_MUST_USE bool emitDefault(ParseNode* defaultExpr, ParseNode* pattern);

    MOZ_MUST_USE bool setOrEmitSetFunName(ParseNode* maybeFun, HandleAtom name,
                                          FunctionPrefixKind prefixKind);

    MOZ_MUST_USE bool emitInitializer(ParseNode* initializer, ParseNode* pattern);
    MOZ_MUST_USE bool emitInitializerInBranch(ParseNode* initializer, ParseNode* pattern);

    MOZ_MUST_USE bool emitCallSiteObject(ParseNode* pn);
    MOZ_MUST_USE bool emitTemplateString(ParseNode* pn);
    MOZ_MUST_USE bool emitAssignment(ParseNode* lhs, JSOp op, ParseNode* rhs);

    MOZ_MUST_USE bool emitReturn(ParseNode* pn);
    MOZ_MUST_USE bool emitStatement(ParseNode* pn);
    MOZ_MUST_USE bool emitStatementList(ParseNode* pn);

    MOZ_MUST_USE bool emitDeleteName(ParseNode* pn);
    MOZ_MUST_USE bool emitDeleteProperty(ParseNode* pn);
    MOZ_MUST_USE bool emitDeleteElement(ParseNode* pn);
    MOZ_MUST_USE bool emitDeleteExpression(ParseNode* pn);

    // |op| must be JSOP_TYPEOF or JSOP_TYPEOFEXPR.
    MOZ_MUST_USE bool emitTypeof(ParseNode* node, JSOp op);

    MOZ_MUST_USE bool emitUnary(ParseNode* pn);
    MOZ_MUST_USE bool emitRightAssociative(ParseNode* pn);
    MOZ_MUST_USE bool emitLeftAssociative(ParseNode* pn);
    MOZ_MUST_USE bool emitLogical(ParseNode* pn);
    MOZ_MUST_USE bool emitSequenceExpr(ParseNode* pn);

    MOZ_NEVER_INLINE MOZ_MUST_USE bool emitIncOrDec(ParseNode* pn);

    MOZ_MUST_USE bool emitConditionalExpression(ConditionalExpression& conditional);

    MOZ_MUST_USE bool isRestParameter(ParseNode* pn, bool* result);
    MOZ_MUST_USE bool emitOptimizeSpread(ParseNode* arg0, JumpList* jmp, bool* emitted);

    MOZ_MUST_USE bool emitCallOrNew(ParseNode* pn);
    MOZ_MUST_USE bool emitSelfHostedCallFunction(ParseNode* pn);
    MOZ_MUST_USE bool emitSelfHostedResumeGenerator(ParseNode* pn);
    MOZ_MUST_USE bool emitSelfHostedForceInterpreter(ParseNode* pn);
    MOZ_MUST_USE bool emitSelfHostedAllowContentIter(ParseNode* pn);

    MOZ_MUST_USE bool emitComprehensionFor(ParseNode* compFor);
    MOZ_MUST_USE bool emitComprehensionForIn(ParseNode* pn);
    MOZ_MUST_USE bool emitComprehensionForInOrOfVariables(ParseNode* pn, bool* lexicalScope);
    MOZ_MUST_USE bool emitComprehensionForOf(ParseNode* pn);

    MOZ_MUST_USE bool emitDo(ParseNode* pn);
    MOZ_MUST_USE bool emitWhile(ParseNode* pn);

    MOZ_MUST_USE bool emitFor(ParseNode* pn, EmitterScope* headLexicalEmitterScope = nullptr);
    MOZ_MUST_USE bool emitCStyleFor(ParseNode* pn, EmitterScope* headLexicalEmitterScope);
    MOZ_MUST_USE bool emitForIn(ParseNode* pn, EmitterScope* headLexicalEmitterScope);
    MOZ_MUST_USE bool emitForOf(ParseNode* pn, EmitterScope* headLexicalEmitterScope);

    MOZ_MUST_USE bool emitInitializeForInOrOfTarget(ParseNode* forHead);

    MOZ_MUST_USE bool emitBreak(PropertyName* label);
    MOZ_MUST_USE bool emitContinue(PropertyName* label);

    MOZ_MUST_USE bool emitFunctionFormalParametersAndBody(ParseNode* pn);
    MOZ_MUST_USE bool emitFunctionFormalParameters(ParseNode* pn);
    MOZ_MUST_USE bool emitInitializeFunctionSpecialNames();
    MOZ_MUST_USE bool emitFunctionBody(ParseNode* pn);
    MOZ_MUST_USE bool emitLexicalInitialization(ParseNode* pn);

    // Emit bytecode for the spread operator.
    //
    // emitSpread expects the current index (I) of the array, the array itself
    // and the iterator to be on the stack in that order (iterator on the bottom).
    // It will pop the iterator and I, then iterate over the iterator by calling
    // |.next()| and put the results into the I-th element of array with
    // incrementing I, then push the result I (it will be original I +
    // iteration count). The stack after iteration will look like |ARRAY INDEX|.
    MOZ_MUST_USE bool emitSpread(bool allowSelfHosted = false);

    MOZ_MUST_USE bool emitClass(ParseNode* pn);
    MOZ_MUST_USE bool emitSuperPropLHS(ParseNode* superBase, bool isCall = false);
    MOZ_MUST_USE bool emitSuperPropOp(ParseNode* pn, JSOp op, bool isCall = false);
    MOZ_MUST_USE bool emitSuperElemOperands(ParseNode* pn,
                                            EmitElemOption opts = EmitElemOption::Get);
    MOZ_MUST_USE bool emitSuperElemOp(ParseNode* pn, JSOp op, bool isCall = false);
};

} /* namespace frontend */
} /* namespace js */

#endif /* frontend_BytecodeEmitter_h */