author Gurzau Raul <rgurzau@mozilla.com>
Tue, 12 Feb 2019 00:57:43 +0200
changeset 503128 738860a7d63307eee5ce83a7e066b7faa224cd16
parent 503126 7cab6219f4dbda4b239b701f33a8aa729207c247
child 503217 d09e3e887cdf5989b62a8b22d622fd5366e9bb73
permissions -rw-r--r--
Backed out changeset 7cab6219f4db (bug 1523791) for failing at src/js/src/frontend/ObjectEmitter.cpp on a CLOSED TREE

/* -*- 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/. */

/* JS bytecode generation. */

#ifndef frontend_BytecodeEmitter_h
#define frontend_BytecodeEmitter_h

#include "mozilla/Attributes.h"
#include "mozilla/Span.h"

#include "ds/InlineTable.h"
#include "frontend/BCEParserHandle.h"
#include "frontend/EitherParser.h"
#include "frontend/JumpList.h"
#include "frontend/NameFunctions.h"
#include "frontend/ParseNode.h"
#include "frontend/SharedContext.h"
#include "frontend/SourceNotes.h"
#include "frontend/ValueUsage.h"
#include "vm/BytecodeUtil.h"
#include "vm/Interpreter.h"
#include "vm/Iteration.h"

namespace js {
namespace frontend {

class CGNumberList {
  Rooted<ValueVector> vector;

  explicit CGNumberList(JSContext* cx) : vector(cx, ValueVector(cx)) {}
  MOZ_MUST_USE bool append(const Value& v) { return vector.append(v); }
  size_t length() const { return vector.length(); }
  void finish(mozilla::Span<GCPtrValue> 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);
  void finish(mozilla::Span<GCPtrObject> array);

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

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

  bool append(Scope* scope) { return vector.append(scope); }
  uint32_t length() const { return vector.length(); }
  void finish(mozilla::Span<GCPtrScope> array);

struct CGTryNoteList {
  Vector<JSTryNote> list;
  explicit CGTryNoteList(JSContext* 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(mozilla::Span<JSTryNote> array);

struct CGScopeNote : public ScopeNote {
  // The end offset. Used to compute the length.
  uint32_t end;

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

  MOZ_MUST_USE bool append(uint32_t scopeIndex, uint32_t offset,
                           uint32_t parent);
  void recordEnd(uint32_t index, uint32_t offse);
  size_t length() const { return list.length(); }
  void finish(mozilla::Span<ScopeNote> array);

struct CGResumeOffsetList {
  Vector<uint32_t> list;
  explicit CGResumeOffsetList(JSContext* cx) : list(cx) {}

  MOZ_MUST_USE bool append(uint32_t offset) { return list.append(offset); }
  size_t length() const { return list.length(); }
  void finish(mozilla::Span<uint32_t> array);

// Have a few inline elements, so as to avoid heap allocation for tiny
// sequences.  See bug 1390526.
typedef Vector<jsbytecode, 64> BytecodeVector;
typedef Vector<jssrcnote, 64> SrcNotesVector;

class CallOrNewEmitter;
class ElemOpEmitter;
class EmitterScope;
class NestableControl;
class PropertyEmitter;
class TDZCheckCache;

struct MOZ_STACK_CLASS BytecodeEmitter {
  SharedContext* const
      sc; /* context shared between parsing and bytecode generation */

  JSContext* 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. */

  BytecodeVector code_;  /* bytecode */
  SrcNotesVector notes_; /* source notes, see below */

  ptrdiff_t lastNoteOffset_; /* code offset for last source note */

  // Line number for srcnotes.
  // WARNING: If this becomes out of sync with already-emitted srcnotes,
  // we can get undefined behavior.
  uint32_t currentLine_;

  // Zero-based column index on currentLine of last SRC_COLSPAN-annotated
  // opcode.
  // WARNING: If this becomes out of sync with already-emitted srcnotes,
  // we can get undefined behavior.
  uint32_t lastColumn_;

  // switchToMain sets this to the bytecode offset of the main section.
  mozilla::Maybe<uint32_t> mainOffset_;

  JumpTarget lastTarget;  // Last jump target emitted.

  // Private storage for parser wrapper. DO NOT REFERENCE INTERNALLY. May not be
  // initialized. Use |parser| instead.
  mozilla::Maybe<EitherParser> ep_;
  BCEParserHandle* 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 bodyScopeIndex; /* index into scopeList of the body scope */

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

#ifdef DEBUG
  bool unstableEmitterScope;

  friend class AutoCheckUnstableEmitterScope;

  EmitterScope* innermostEmitterScope() const {
    return innermostEmitterScopeNoCheck();
  EmitterScope* innermostEmitterScopeNoCheck() const {
    return innermostEmitterScope_;

  CGNumberList numberList;       /* double and bigint values used by 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 */

  // Certain ops (yield, await, gosub) have an entry in the script's
  // resumeOffsets list. This can be used to map from the op's resumeIndex to
  // the bytecode offset of the next pc. This indirection makes it easy to
  // resume in the JIT (because BaselineScript stores a resumeIndex => native
  // code array).
  CGResumeOffsetList resumeOffsetList;

  // Number of JOF_IC opcodes emitted.
  size_t numICEntries;

  // Number of yield instructions emitted. Does not include JSOP_AWAIT.
  uint32_t numYields;

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

      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 {

     * 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.

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

  const EmitterMode emitterMode;

  MOZ_INIT_OUTSIDE_CTOR uint32_t scriptStartOffset;
  bool scriptStartOffsetSet;

  // The end location of a function body that is being emitted.
  MOZ_INIT_OUTSIDE_CTOR 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.
  // Internal constructor, for delegation use only.
  BytecodeEmitter(BytecodeEmitter* parent, SharedContext* sc,
                  HandleScript script, Handle<LazyScript*> lazyScript,
                  uint32_t lineNum, EmitterMode emitterMode);

  void initFromBodyPosition(TokenPos bodyPosition);

   * Helper for reporting that we have insufficient args.  pluralizer
   * should be "s" if requiredArgs is anything other than "1" and ""
   * if requiredArgs is "1".
  void reportNeedMoreArgsError(ParseNode* pn, const char* errorName,
                               const char* requiredArgs, const char* pluralizer,
                               const ListNode* argsList);

  BytecodeEmitter(BytecodeEmitter* parent, BCEParserHandle* parser,
                  SharedContext* sc, HandleScript script,
                  Handle<LazyScript*> lazyScript, uint32_t lineNum,
                  EmitterMode emitterMode = Normal);

  BytecodeEmitter(BytecodeEmitter* parent, const EitherParser& parser,
                  SharedContext* sc, HandleScript script,
                  Handle<LazyScript*> lazyScript, uint32_t lineNum,
                  EmitterMode emitterMode = Normal);

  template <typename Unit>
  BytecodeEmitter(BytecodeEmitter* parent,
                  Parser<FullParseHandler, Unit>* parser, SharedContext* sc,
                  HandleScript script, Handle<LazyScript*> lazyScript,
                  uint32_t lineNum, EmitterMode emitterMode = Normal)
      : BytecodeEmitter(parent, EitherParser(parser), sc, script, lazyScript,
                        lineNum, emitterMode) {}

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

  BytecodeEmitter(BytecodeEmitter* parent, const EitherParser& parser,
                  SharedContext* sc, HandleScript script,
                  Handle<LazyScript*> lazyScript, TokenPos bodyPosition,
                  EmitterMode emitterMode = Normal)
      : BytecodeEmitter(parent, parser, sc, script, lazyScript,
                        emitterMode) {

  template <typename Unit>
  BytecodeEmitter(BytecodeEmitter* parent,
                  Parser<FullParseHandler, Unit>* parser, SharedContext* sc,
                  HandleScript script, Handle<LazyScript*> lazyScript,
                  TokenPos bodyPosition, EmitterMode emitterMode = Normal)
      : BytecodeEmitter(parent, EitherParser(parser), sc, script, lazyScript,
                        bodyPosition, emitterMode) {}

  MOZ_MUST_USE bool init();

  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) {
    varEmitterScope = emitterScope;

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

  MOZ_MUST_USE bool makeAtomIndex(JSAtom* atom, uint32_t* indexp) {
    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 emitThisEnvironmentCallee();
  MOZ_MUST_USE bool emitSuperBase();

  void tellDebuggerAboutCompiledScript(JSContext* cx);

  BytecodeVector& code() { return code_; }
  const BytecodeVector& code() const { return code_; }

  jsbytecode* code(ptrdiff_t offset) { return code_.begin() + offset; }
  ptrdiff_t offset() const { return code_.end() - code_.begin(); }

  uint32_t mainOffset() const { return *mainOffset_; }

  bool inPrologue() const { return mainOffset_.isNothing(); }

  void switchToMain() {

  SrcNotesVector& notes() {
    // Prologue shouldn't have source notes.
    return notes_;
  ptrdiff_t lastNoteOffset() const { return lastNoteOffset_; }
  unsigned currentLine() const { return currentLine_; }

  void setCurrentLine(uint32_t line) {
    currentLine_ = line;
    lastColumn_ = 0;

  // Check if the last emitted opcode is a jump target.
  bool lastOpcodeIsJumpTarget() const {
    return offset() - 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() ? lastTarget.offset : offset();

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

  void setScriptStartOffsetIfUnset(TokenPos pos) {
    if (!scriptStartOffsetSet) {
      scriptStartOffset = pos.begin;
      scriptStartOffsetSet = true;

  void reportError(ParseNode* pn, unsigned errorNumber, ...);
  void reportError(const mozilla::Maybe<uint32_t>& maybeOffset,
                   unsigned errorNumber, ...);
  bool reportExtraWarning(ParseNode* pn, unsigned errorNumber, ...);
  bool reportExtraWarning(const mozilla::Maybe<uint32_t>& maybeOffset,
                          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);

  // Add TryNote to the tryNoteList array. The start and end offset are
  // relative to current section.
  MOZ_MUST_USE bool addTryNote(JSTryNoteKind kind, uint32_t stackDepth,
                               size_t start, size_t end);

  // 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);

  // Control whether emitTree emits a line number note.

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

  // 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.
  enum class TopLevelFunction { No, Yes };
  MOZ_MUST_USE bool emitFunctionScript(FunctionNode* funNode,
                                       TopLevelFunction isTopLevel);

  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(JSOp op, 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_POP or JSOP_POPN.
  MOZ_MUST_USE bool emitPopN(unsigned n);

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

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

  // Push whether the value atop of the stack is non-undefined and non-null.
  MOZ_MUST_USE bool emitPushNotUndefinedOrNull();

  // 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 emitBigIntOp(BigInt* bigint);

  MOZ_MUST_USE bool emitThisLiteral(ThisLiteral* pn);
  MOZ_MUST_USE bool emitGetFunctionThis(NameNode* thisName);
  MOZ_MUST_USE bool emitGetFunctionThis(const mozilla::Maybe<uint32_t>& offset);
  MOZ_MUST_USE bool emitGetThisForSuperBase(UnaryNode* superBase);
  MOZ_MUST_USE bool emitSetThis(BinaryNode* setThisNode);
  MOZ_MUST_USE bool emitCheckDerivedClassConstructorReturn();

  // Handle jump opcodes and jump targets.
  MOZ_MUST_USE bool emitJumpTargetOp(JSOp op, ptrdiff_t* off);
  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,
                             const mozilla::Maybe<uint32_t>& sourceCoordOffset);
  MOZ_MUST_USE bool emitCall(JSOp op, uint16_t argc, ParseNode* pn = nullptr);
  MOZ_MUST_USE bool emitCallIncDec(UnaryNode* incDec);

  mozilla::Maybe<uint32_t> getOffsetForLoop(ParseNode* nextpn);

  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(uint32_t atomIndex, JSOp op);

  MOZ_MUST_USE bool emitArrayLiteral(ListNode* array);
  MOZ_MUST_USE bool emitArray(ParseNode* arrayHead, uint32_t count);

  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(FunctionNode* funNode,
                                                  bool needsProto = false);
  MOZ_NEVER_INLINE MOZ_MUST_USE bool emitObject(ListNode* objNode);

  MOZ_MUST_USE bool replaceNewInitWithNewObject(JSObject* obj,
                                                ptrdiff_t offset);

  MOZ_MUST_USE bool emitHoistedFunctionsInList(ListNode* stmtList);

  MOZ_MUST_USE bool emitPropertyList(ListNode* obj, PropertyEmitter& pe,
                                     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);
  MOZ_MUST_USE bool emitGetName(JSAtom* name) {
    return emitGetNameAtLocation(name, lookupName(name));
  MOZ_MUST_USE bool emitGetName(NameNode* name);

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

  MOZ_MUST_USE bool emitNameIncDec(UnaryNode* incDec);

  MOZ_MUST_USE bool emitDeclarationList(ListNode* declList);
  MOZ_MUST_USE bool emitSingleDeclaration(ListNode* declList, NameNode* decl,
                                          ParseNode* initializer);

  MOZ_MUST_USE bool emitNewInit();
  MOZ_MUST_USE bool emitSingletonInitialiser(ListNode* objOrArray);

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

  MOZ_MUST_USE bool emitGetDotGeneratorInInnermostScope() {
    return emitGetDotGeneratorInScope(*innermostEmitterScope());
  MOZ_MUST_USE bool emitGetDotGeneratorInScope(EmitterScope& currentScope);

  MOZ_MUST_USE bool allocateResumeIndex(ptrdiff_t offset,
                                        uint32_t* resumeIndex);
  MOZ_MUST_USE bool allocateResumeIndexRange(mozilla::Span<ptrdiff_t> offsets,
                                             uint32_t* firstResumeIndex);

  MOZ_MUST_USE bool emitInitialYield(UnaryNode* yieldNode);
  MOZ_MUST_USE bool emitYield(UnaryNode* yieldNode);
  MOZ_MUST_USE bool emitYieldOp(JSOp op);
  MOZ_MUST_USE bool emitYieldStar(ParseNode* iter);
  MOZ_MUST_USE bool emitAwaitInInnermostScope() {
    return emitAwaitInScope(*innermostEmitterScope());
  MOZ_MUST_USE bool emitAwaitInInnermostScope(UnaryNode* awaitNode);
  MOZ_MUST_USE bool emitAwaitInScope(EmitterScope& currentScope);

  MOZ_MUST_USE bool emitPropLHS(PropertyAccess* prop);
  MOZ_MUST_USE bool emitPropIncDec(UnaryNode* incDec);

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

  MOZ_MUST_USE bool emitComputedPropertyName(UnaryNode* 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, Call, IncDec, CompoundAssign, Ref };
  MOZ_MUST_USE bool emitElemOperands(PropertyByValue* elem,
                                     EmitElemOption opts);

  MOZ_MUST_USE bool emitElemObjAndKey(PropertyByValue* elem, bool isSuper,
                                      ElemOpEmitter& eoe);
  MOZ_MUST_USE bool emitElemOpBase(JSOp op);
  MOZ_MUST_USE bool emitElemOp(PropertyByValue* elem, JSOp op);
  MOZ_MUST_USE bool emitElemIncDec(UnaryNode* incDec);

  MOZ_MUST_USE bool emitCatch(BinaryNode* catchClause);
  MOZ_MUST_USE bool emitIf(TernaryNode* ifNode);
  MOZ_MUST_USE bool emitWith(BinaryNode* withNode);

  MOZ_NEVER_INLINE MOZ_MUST_USE bool emitLabeledStatement(
      const LabeledStatement* labeledStmt);
  MOZ_NEVER_INLINE MOZ_MUST_USE bool emitLexicalScope(
      LexicalScopeNode* lexicalScope);
  MOZ_MUST_USE bool emitLexicalScopeBody(
      ParseNode* body, EmitLineNumberNote emitLineNote = EMIT_LINENOTE);
  MOZ_NEVER_INLINE MOZ_MUST_USE bool emitSwitch(SwitchStatement* switchStmt);
  MOZ_NEVER_INLINE MOZ_MUST_USE bool emitTry(TryNode* tryNode);

  MOZ_MUST_USE bool emitGoSub(JumpList* jump);

  enum DestructuringFlavor {
    // Destructuring into a declaration.

    // 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.

    // Destructuring as part of an AssignmentExpression.

  // 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);

  // emitDestructuringObjRestExclusionSet emits the property exclusion set
  // for the rest-property in an object pattern.
  MOZ_MUST_USE bool emitDestructuringObjRestExclusionSet(ListNode* pattern);

  // 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(ListNode* pattern,
                                         DestructuringFlavor flav);
  MOZ_MUST_USE bool emitDestructuringOpsArray(ListNode* pattern,
                                              DestructuringFlavor flav);
  MOZ_MUST_USE bool emitDestructuringOpsObject(ListNode* pattern,
                                               DestructuringFlavor flav);

  enum class CopyOption { Filtered, Unfiltered };

  // Calls either the |CopyDataProperties| or the
  // |CopyDataPropertiesUnfiltered| intrinsic function, consumes three (or
  // two in the latter case) elements from the stack.
  MOZ_MUST_USE bool emitCopyDataProperties(CopyOption option);

  // 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();

  MOZ_MUST_USE bool emitAsyncIterator();

  // Pops iterator from the top of the stack. Pushes the result of |.next()|
  // onto the stack.
  MOZ_MUST_USE bool emitIteratorNext(
      const mozilla::Maybe<uint32_t>& callSourceCoordOffset,
      IteratorKind kind = IteratorKind::Sync, bool allowSelfHosted = false);
  MOZ_MUST_USE bool emitIteratorCloseInScope(
      EmitterScope& currentScope, IteratorKind iterKind = IteratorKind::Sync,
      CompletionKind completionKind = CompletionKind::Normal,
      bool allowSelfHosted = false);
  MOZ_MUST_USE bool emitIteratorCloseInInnermostScope(
      IteratorKind iterKind = IteratorKind::Sync,
      CompletionKind completionKind = CompletionKind::Normal,
      bool allowSelfHosted = false) {
    return emitIteratorCloseInScope(*innermostEmitterScope(), iterKind,
                                    completionKind, allowSelfHosted);

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

  MOZ_MUST_USE bool defineHoistedTopLevelFunctions(ParseNode* body);

  // 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);

  MOZ_MUST_USE bool setFunName(JSFunction* fun, JSAtom* name);
  MOZ_MUST_USE bool emitSetClassConstructorName(JSAtom* name);
  MOZ_MUST_USE bool emitInitializer(ParseNode* initializer, ParseNode* pattern);

  MOZ_MUST_USE bool emitCallSiteObject(CallSiteNode* callSiteObj);
  MOZ_MUST_USE bool emitTemplateString(ListNode* templateString);
  MOZ_MUST_USE bool emitAssignment(ParseNode* lhs, JSOp compoundOp,
                                   ParseNode* rhs);

  MOZ_MUST_USE bool emitReturn(UnaryNode* returnNode);
  MOZ_MUST_USE bool emitExpressionStatement(UnaryNode* exprStmt);
  MOZ_MUST_USE bool emitStatementList(ListNode* stmtList);

  MOZ_MUST_USE bool emitDeleteName(UnaryNode* deleteNode);
  MOZ_MUST_USE bool emitDeleteProperty(UnaryNode* deleteNode);
  MOZ_MUST_USE bool emitDeleteElement(UnaryNode* deleteNode);
  MOZ_MUST_USE bool emitDeleteExpression(UnaryNode* deleteNode);

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

  MOZ_MUST_USE bool emitUnary(UnaryNode* unaryNode);
  MOZ_MUST_USE bool emitRightAssociative(ListNode* node);
  MOZ_MUST_USE bool emitLeftAssociative(ListNode* node);
  MOZ_MUST_USE bool emitLogical(ListNode* node);
  MOZ_MUST_USE bool emitSequenceExpr(
      ListNode* node, ValueUsage valueUsage = ValueUsage::WantValue);

  MOZ_NEVER_INLINE MOZ_MUST_USE bool emitIncOrDec(UnaryNode* incDec);

  MOZ_MUST_USE bool emitConditionalExpression(
      ConditionalExpression& conditional,
      ValueUsage valueUsage = ValueUsage::WantValue);

  bool isRestParameter(ParseNode* expr);

  MOZ_MUST_USE bool emitArguments(ListNode* argsList, bool isCall,
                                  bool isSpread, CallOrNewEmitter& cone);
  MOZ_MUST_USE bool emitCallOrNew(
      BinaryNode* callNode, ValueUsage valueUsage = ValueUsage::WantValue);
  MOZ_MUST_USE bool emitSelfHostedCallFunction(BinaryNode* callNode);
  MOZ_MUST_USE bool emitSelfHostedResumeGenerator(BinaryNode* callNode);
  MOZ_MUST_USE bool emitSelfHostedForceInterpreter();
  MOZ_MUST_USE bool emitSelfHostedAllowContentIter(BinaryNode* callNode);
  MOZ_MUST_USE bool emitSelfHostedDefineDataProperty(BinaryNode* callNode);
  MOZ_MUST_USE bool emitSelfHostedGetPropertySuper(BinaryNode* callNode);
  MOZ_MUST_USE bool emitSelfHostedHasOwn(BinaryNode* callNode);

  MOZ_MUST_USE bool emitDo(BinaryNode* doNode);
  MOZ_MUST_USE bool emitWhile(BinaryNode* whileNode);

  MOZ_MUST_USE bool emitFor(
      ForNode* forNode, const EmitterScope* headLexicalEmitterScope = nullptr);
  MOZ_MUST_USE bool emitCStyleFor(ForNode* forNode,
                                  const EmitterScope* headLexicalEmitterScope);
  MOZ_MUST_USE bool emitForIn(ForNode* forNode,
                              const EmitterScope* headLexicalEmitterScope);
  MOZ_MUST_USE bool emitForOf(ForNode* forNode,
                              const EmitterScope* headLexicalEmitterScope);

  MOZ_MUST_USE bool emitInitializeForInOrOfTarget(TernaryNode* forHead);

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

  MOZ_MUST_USE bool emitFunctionFormalParametersAndBody(ListNode* paramsBody);
  MOZ_MUST_USE bool emitFunctionFormalParameters(ListNode* paramsBody);
  MOZ_MUST_USE bool emitInitializeFunctionSpecialNames();
  MOZ_MUST_USE bool emitFunctionBody(ParseNode* funBody);
  MOZ_MUST_USE bool emitLexicalInitialization(NameNode* name);
  MOZ_MUST_USE bool emitLexicalInitialization(JSAtom* name);

  // 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(ClassNode* classNode);
  MOZ_MUST_USE bool emitSuperElemOperands(
      PropertyByValue* elem, EmitElemOption opts = EmitElemOption::Get);
  MOZ_MUST_USE bool emitSuperGetElem(PropertyByValue* elem,
                                     bool isCall = false);

  MOZ_MUST_USE bool emitCalleeAndThis(ParseNode* callee, ParseNode* call,
                                      CallOrNewEmitter& cone);

  MOZ_MUST_USE bool emitPipeline(ListNode* node);

  MOZ_MUST_USE bool emitExportDefault(BinaryNode* exportNode);

class MOZ_RAII AutoCheckUnstableEmitterScope {
#ifdef DEBUG
  bool prev_;
  BytecodeEmitter* bce_;

  AutoCheckUnstableEmitterScope() = delete;
  explicit AutoCheckUnstableEmitterScope(BytecodeEmitter* bce)
#ifdef DEBUG
      : bce_(bce)
#ifdef DEBUG
    prev_ = bce_->unstableEmitterScope;
    bce_->unstableEmitterScope = true;
  ~AutoCheckUnstableEmitterScope() {
#ifdef DEBUG
    bce_->unstableEmitterScope = prev_;

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

#endif /* frontend_BytecodeEmitter_h */