引擎剖析：JS 中的字符串转数值

Handle<JSFunction> number_fun = InstallFunction(isolate_, global, "Number", JS_PRIMITIVE_WRAPPER_TYPE, JSPrimitiveWrapper::kHeaderSize, 0, isolate_->initial_object_prototype(), Builtin::kNumberConstructor);

// Install Number.parseInt and Global.parseInt.
Handle<JSFunction> parse_int_fun = SimpleInstallFunction(isolate_, number_fun, "parseInt", Builtin::kNumberParseInt, 2, true);

JSObject::AddProperty(isolate_, global_object, "parseInt", parse_int_fun,
 native_context()->set_global_parse_int_fun(*parse_int_fun);

// Convenience macro to avoid generating named accessors for all builtins.
#define BUILTIN_CODE(isolate, name) \
  (isolate)->builtins()->code_handle(i::Builtin::k##name)

// ES6 #sec-number.parseint
transitioning javascript builtin NumberParseInt(
    js-implicit context: NativeContext)(value: JSAny, radix: JSAny): Number {
  return ParseInt(value, radix);
}


transitioning builtin ParseInt(implicit context: Context)(
    input: JSAny, radix: JSAny): Number {
  try {
    // Check if radix should be 10 (i.e. undefined, 0 or 10).
    if (radix != Undefined && !TaggedEqual(radix, SmiConstant(10)) &&
        !TaggedEqual(radix, SmiConstant(0))) {
      goto CallRuntime;
    }

    typeswitch (input) {
      case (s: Smi): {
        return s;
      }
      case (h: HeapNumber): {
        // Check if the input value is in Signed32 range.
        const asFloat64: float64 = Convert<float64>(h);
        const asInt32: int32 = Signed(TruncateFloat64ToWord32(asFloat64));
        // The sense of comparison is important for the NaN case.
        if (asFloat64 == ChangeInt32ToFloat64(asInt32)) goto Int32(asInt32);

        // Check if the absolute value of input is in the [1,1<<31[ range. Call
        // the runtime for the range [0,1[ because the result could be -0.
        const kMaxAbsValue: float64 = 2147483648.0;
        const absInput: float64 = math::Float64Abs(asFloat64);
        if (absInput < kMaxAbsValue && absInput >= 1.0) goto Int32(asInt32);
        goto CallRuntime;
      }
      case (s: String): {
        goto String(s);
      }
      case (HeapObject): {
        goto CallRuntime;
      }
    }
  } label Int32(i: int32) {
    return ChangeInt32ToTagged(i);
  } label String(s: String) {
    // Check if the string is a cached array index.
    const hash: NameHash = s.raw_hash_field;
    if (IsIntegerIndex(hash) &&
        hash.array_index_length < kMaxCachedArrayIndexLength) {
      const arrayIndex: uint32 = hash.array_index_value;
      return SmiFromUint32(arrayIndex);
    }
    // Fall back to the runtime.
    goto CallRuntime;
  } label CallRuntime {
    tail runtime::StringParseInt(input, radix);
  }
}

// ES6 18.2.5 parseInt(string, radix) slow path
RUNTIME_FUNCTION(Runtime_StringParseInt) {
  HandleScope handle_scope(isolate);
  DCHECK_EQ(2, args.length());
  Handle<Object> string = args.at(0);
  Handle<Object> radix = args.at(1);

  // Convert {string} to a String first, and flatten it.
  Handle<String> subject;
  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, subject,
                                     Object::ToString(isolate, string));
  subject = String::Flatten(isolate, subject);

  // Convert {radix} to Int32.
  if (!radix->IsNumber()) {
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, radix,
                                       Object::ToNumber(isolate, radix));
  }
  int radix32 = DoubleToInt32(radix->Number());
  if (radix32 != 0 && (radix32 < 2 || radix32 > 36)) {
    return ReadOnlyRoots(isolate).nan_value();
  }

  double result = StringToInt(isolate, subject, radix32);
  return *isolate->factory()->NewNumber(result);
}

JSC_DEFINE_HOST_FUNCTION(globalFuncParseInt, (JSGlobalObject* globalObject, CallFrame* callFrame))
{
    JSValue value = callFrame->argument(0);
    JSValue radixValue = callFrame->argument(1);

    // Optimized handling for numbers:
    // If the argument is 0 or a number in range 10^-6 <= n < INT_MAX+1, then parseInt
    // results in a truncation to integer. In the case of -0, this is converted to 0.
    //
    // This is also a truncation for values in the range INT_MAX+1 <= n < 10^21,
    // however these values cannot be trivially truncated to int since 10^21 exceeds
    // even the int64_t range. Negative numbers are a little trickier, the case for
    // values in the range -10^21 < n <= -1 are similar to those for integer, but
    // values in the range -1 < n <= -10^-6 need to truncate to -0, not 0.
    static const double tenToTheMinus6 = 0.000001;
    static const double intMaxPlusOne = 2147483648.0;
    if (value.isNumber()) {
        double n = value.asNumber();
        if (((n < intMaxPlusOne && n >= tenToTheMinus6) || !n) && radixValue.isUndefinedOrNull())
            return JSValue::encode(jsNumber(static_cast<int32_t>(n)));
    }

    // If ToString throws, we shouldn't call ToInt32.
    return toStringView(globalObject, value, [&] (StringView view) {
        return JSValue::encode(jsNumber(parseInt(view, radixValue.toInt32(globalObject))));
    });
}

ALWAYS_INLINE static bool isStrWhiteSpace(UChar c)
{
    // https://tc39.github.io/ecma262/#sec-tonumber-applied-to-the-string-type
    return Lexer<UChar>::isWhiteSpace(c) || Lexer<UChar>::isLineTerminator(c);
}

// ES5.1 15.1.2.2
template <typename CharType>
ALWAYS_INLINE
static double parseInt(StringView s, const CharType* data, int radix)
{
    // 1. Let inputString be ToString(string).
    // 2. Let S be a newly created substring of inputString consisting of the first character that is not a
    //    StrWhiteSpaceChar and all characters following that character. (In other words, remove leading white
    //    space.) If inputString does not contain any such characters, let S be the empty string.
    int length = s.length();
    int p = 0;
    while (p < length && isStrWhiteSpace(data[p]))
        ++p;

    // 3. Let sign be 1.
    // 4. If S is not empty and the first character of S is a minus sign -, let sign be -1.
    // 5. If S is not empty and the first character of S is a plus sign + or a minus sign -, then remove the first character from S.
    double sign = 1;
    if (p < length) {
        if (data[p] == '+')
            ++p;
        else if (data[p] == '-') {
            sign = -1;
            ++p;
        }
    }

    // 6. Let R = ToInt32(radix).
    // 7. Let stripPrefix be true.
    // 8. If R != 0,then
    //   b. If R != 16, let stripPrefix be false.
    // 9. Else, R == 0
    //   a. LetR = 10.
    // 10. If stripPrefix is true, then
    //   a. If the length of S is at least 2 and the first two characters of S are either ―0x or ―0X,
    //      then remove the first two characters from S and let R = 16.
    // 11. If S contains any character that is not a radix-R digit, then let Z be the substring of S
    //     consisting of all characters before the first such character; otherwise, let Z be S.
    if ((radix == 0 || radix == 16) && length - p >= 2 && data[p] == '0' && (data[p + 1] == 'x' || data[p + 1] == 'X')) {
        radix = 16;
        p += 2;
    } else if (radix == 0)
        radix = 10;

    // 8.a If R < 2 or R > 36, then return NaN.
    if (radix < 2 || radix > 36)
        return PNaN;

    // 13. Let mathInt be the mathematical integer value that is represented by Z in radix-R notation, using the letters
    //     A-Z and a-z for digits with values 10 through 35. (However, if R is 10 and Z contains more than 20 significant
    //     digits, every significant digit after the 20th may be replaced by a 0 digit, at the option of the implementation;
    //     and if R is not 2, 4, 8, 10, 16, or 32, then mathInt may be an implementation-dependent approximation to the
    //     mathematical integer value that is represented by Z in radix-R notation.)
    // 14. Let number be the Number value for mathInt.
    int firstDigitPosition = p;
    bool sawDigit = false;
    double number = 0;
    while (p < length) {
        int digit = parseDigit(data[p], radix);
        if (digit == -1)
            break;
        sawDigit = true;
        number *= radix;
        number += digit;
        ++p;
    }

    // 12. If Z is empty, return NaN.
    if (!sawDigit)
        return PNaN;

    // Alternate code path for certain large numbers.
    if (number >= mantissaOverflowLowerBound) {
        if (radix == 10) {
            size_t parsedLength;
            number = parseDouble(s.substring(firstDigitPosition, p - firstDigitPosition), parsedLength);
        } else if (radix == 2 || radix == 4 || radix == 8 || radix == 16 || radix == 32)
            number = parseIntOverflow(s.substring(firstDigitPosition, p - firstDigitPosition), radix);
    }

    // 15. Return sign x number.
    return sign * number;
}

ALWAYS_INLINE static double parseInt(StringView s, int radix)
{
    if (s.is8Bit())
        return parseInt(s, s.characters8(), radix);
    return parseInt(s, s.characters16(), radix);
}

template<typename CallbackWhenNoException>
static ALWAYS_INLINE typename std::invoke_result<CallbackWhenNoException, StringView>::type toStringView(JSGlobalObject* globalObject, JSValue value, CallbackWhenNoException callback)
{
    VM& vm = getVM(globalObject);
    auto scope = DECLARE_THROW_SCOPE(vm);
    JSString* string = value.toStringOrNull(globalObject);
    EXCEPTION_ASSERT(!!scope.exception() == !string);
    if (UNLIKELY(!string))
        return { };
    auto viewWithString = string->viewWithUnderlyingString(globalObject);
    RETURN_IF_EXCEPTION(scope, { });
    RELEASE_AND_RETURN(scope, callback(viewWithString.view));
}

// Mapping from integers 0..35 to digit identifying this value, for radix 2..36.
const char radixDigits[] = "0123456789abcdefghijklmnopqrstuvwxyz";

/* global object */
static const JSCFunctionListEntry js_global_funcs[] = {
    JS_CFUNC_DEF("parseInt", 2, js_parseInt ),
//...
}

static JSValue js_parseInt(JSContext *ctx, JSValueConst this_val,
                           int argc, JSValueConst *argv)
{
    const char *str, *p;
    int radix, flags;
    JSValue ret;

    str = JS_ToCString(ctx, argv[0]);
    if (!str)
        return JS_EXCEPTION;
    if (JS_ToInt32(ctx, &radix, argv[1])) {
        JS_FreeCString(ctx, str);
        return JS_EXCEPTION;
    }
    if (radix != 0 && (radix < 2 || radix > 36)) {
        ret = JS_NAN;
    } else {
        p = str;
        p += skip_spaces(p);
        flags = ATOD_INT_ONLY | ATOD_ACCEPT_PREFIX_AFTER_SIGN;
        ret = js_atof(ctx, p, NULL, radix, flags);
    }
    JS_FreeCString(ctx, str);
    return ret;
}

// ES6 #sec-number.parsefloat
transitioning javascript builtin NumberParseFloat(
    js-implicit context: NativeContext)(value: JSAny): Number {
  try {
    typeswitch (value) {
      case (s: Smi): {
        return s;
      }
      case (h: HeapNumber): {
        // The input is already a Number. Take care of -0.
        // The sense of comparison is important for the NaN case.
        return (Convert<float64>(h) == 0) ? SmiConstant(0) : h;
      }
      case (s: String): {
        goto String(s);
      }
      case (HeapObject): {
        goto String(string::ToString(context, value));
      }
    }
  } label String(s: String) {
    // Check if the string is a cached array index.
    const hash: NameHash = s.raw_hash_field;
    if (IsIntegerIndex(hash) &&
        hash.array_index_length < kMaxCachedArrayIndexLength) {
      const arrayIndex: uint32 = hash.array_index_value;
      return SmiFromUint32(arrayIndex);
    }
    // Fall back to the runtime to convert string to a number.
    return runtime::StringParseFloat(s);
  }
}

// ES6 18.2.4 parseFloat(string)
RUNTIME_FUNCTION(Runtime_StringParseFloat) {
  HandleScope shs(isolate);
  DCHECK_EQ(1, args.length());
  Handle<String> subject = args.at<String>(0);

  double value = StringToDouble(isolate, subject, ALLOW_TRAILING_JUNK,
                                std::numeric_limits<double>::quiet_NaN());

  return *isolate->factory()->NewNumber(value);
}

static double parseFloat(StringView s)
{
    unsigned size = s.length();

    if (size == 1) {
        UChar c = s[0];
        if (isASCIIDigit(c))
            return c - '0';
        return PNaN;
    }

    if (s.is8Bit()) {
        const LChar* data = s.characters8();
        const LChar* end = data + size;

        // Skip leading white space.
        for (; data < end; ++data) {
            if (!isStrWhiteSpace(*data))
                break;
        }

        // Empty string.
        if (data == end)
            return PNaN;

        return jsStrDecimalLiteral(data, end);
    }

    const UChar* data = s.characters16();
    const UChar* end = data + size;

    // Skip leading white space.
    for (; data < end; ++data) {
        if (!isStrWhiteSpace(*data))
            break;
    }

    // Empty string.
    if (data == end)
        return PNaN;

    return jsStrDecimalLiteral(data, end);
}

static JSValue js_parseFloat(JSContext *ctx, JSValueConst this_val,
                             int argc, JSValueConst *argv)
{
    const char *str, *p;
    JSValue ret;

    str = JS_ToCString(ctx, argv[0]);
    if (!str)
        return JS_EXCEPTION;
    p = str;
    p += skip_spaces(p);
    ret = js_atof(ctx, p, NULL, 10, 0);
    JS_FreeCString(ctx, str);
    return ret;
}

Handle<JSFunction> number_fun = InstallFunction(
        isolate_, global, "Number", JS_PRIMITIVE_WRAPPER_TYPE,
        JSPrimitiveWrapper::kHeaderSize, 0,
        isolate_->initial_object_prototype(), Builtin::kNumberConstructor);
number_fun->shared().DontAdaptArguments();
number_fun->shared().set_length(1);
InstallWithIntrinsicDefaultProto(isolate_, number_fun,
                                     Context::NUMBER_FUNCTION_INDEX);

// Create the %NumberPrototype%
Handle<JSPrimitiveWrapper> prototype = Handle<JSPrimitiveWrapper>::cast(
        factory->NewJSObject(number_fun, AllocationType::kOld));
prototype->set_value(Smi::zero());
JSFunction::SetPrototype(number_fun, prototype);

// Install the "constructor" property on the {prototype}.
JSObject::AddProperty(isolate_, prototype, factory->constructor_string(),
                          number_fun, DONT_ENUM);

// ES #sec-number-constructor
transitioning javascript builtin
NumberConstructor(
    js-implicit context: NativeContext, receiver: JSAny, newTarget: JSAny,
    target: JSFunction)(...arguments): JSAny {
  // 1. If no arguments were passed to this function invocation, let n be +0.
  let n: Number = 0;
  if (arguments.length > 0) {
    // 2. Else,
    //    a. Let prim be ? ToNumeric(value).
    //    b. If Type(prim) is BigInt, let n be the Number value for prim.
    //    c. Otherwise, let n be prim.
    const value = arguments[0];
    n = ToNumber(value, BigIntHandling::kConvertToNumber);
  }

  // 3. If NewTarget is undefined, return n.
  if (newTarget == Undefined) return n;

  // 4. Let O be ? OrdinaryCreateFromConstructor(NewTarget,
  //    "%NumberPrototype%", « [[NumberData]] »).
  // 5. Set O.[[NumberData]] to n.
  // 6. Return O.

  // We ignore the normal target parameter and load the value from the
  // current frame here in order to reduce register pressure on the fast path.
  const target: JSFunction = LoadTargetFromFrame();
  const result = UnsafeCast<JSPrimitiveWrapper>(
      FastNewObject(context, target, UnsafeCast<JSReceiver>(newTarget)));
  result.value = n;
  return result;
}

// ECMA 15.7.1
JSC_DEFINE_HOST_FUNCTION(constructNumberConstructor, (JSGlobalObject* globalObject, CallFrame* callFrame))
{
    VM& vm = globalObject->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);
    double n = 0;
    if (callFrame->argumentCount()) {
        JSValue numeric = callFrame->uncheckedArgument(0).toNumeric(globalObject);
        RETURN_IF_EXCEPTION(scope, { });
        if (numeric.isNumber())
            n = numeric.asNumber();
        else {
            ASSERT(numeric.isBigInt());
            numeric = JSBigInt::toNumber(numeric);
            ASSERT(numeric.isNumber());
            n = numeric.asNumber();
        }
    }

    JSObject* newTarget = asObject(callFrame->newTarget());
    Structure* structure = JSC_GET_DERIVED_STRUCTURE(vm, numberObjectStructure, newTarget, callFrame->jsCallee());
    RETURN_IF_EXCEPTION(scope, { });

    NumberObject* object = NumberObject::create(vm, structure);
    object->setInternalValue(vm, jsNumber(n));
    return JSValue::encode(object);
}

void JS_AddIntrinsicBaseObjects(JSContext *ctx)
{
//...

/* Number */
    ctx->class_proto[JS_CLASS_NUMBER] = JS_NewObjectProtoClass(ctx, ctx->class_proto[JS_CLASS_OBJECT], JS_CLASS_NUMBER);
    
    JS_SetObjectData(ctx, ctx->class_proto[JS_CLASS_NUMBER], JS_NewInt32(ctx, 0));
    JS_SetPropertyFunctionList(ctx, ctx->class_proto[JS_CLASS_NUMBER], js_number_proto_funcs, countof(js_number_proto_funcs));
    
    number_obj = JS_NewGlobalCConstructor(ctx, "Number", js_number_constructor, 1, ctx->class_proto[JS_CLASS_NUMBER]);
    
    JS_SetPropertyFunctionList(ctx, number_obj, js_number_funcs, countof(js_number_funcs));
}

static JSValue js_number_constructor(JSContext *ctx, JSValueConst new_target,
                                     int argc, JSValueConst *argv)
{
    JSValue val, obj;
    if (argc == 0) {
        val = JS_NewInt32(ctx, 0);
    } else {
        val = JS_ToNumeric(ctx, argv[0]);
        if (JS_IsException(val))
            return val;
        switch(JS_VALUE_GET_TAG(val)) {
#ifdef CONFIG_BIGNUM
        case JS_TAG_BIG_INT:
        case JS_TAG_BIG_FLOAT:
            {
                JSBigFloat *p = JS_VALUE_GET_PTR(val);
                double d;
                bf_get_float64(&p->num, &d, BF_RNDN);
                JS_FreeValue(ctx, val);
                val = __JS_NewFloat64(ctx, d);
            }
            break;
        case JS_TAG_BIG_DECIMAL:
            val = JS_ToStringFree(ctx, val);
            if (JS_IsException(val))
                return val;
            val = JS_ToNumberFree(ctx, val);
            if (JS_IsException(val))
                return val;
            break;
#endif
        default:
            break;
        }
    }
    if (!JS_IsUndefined(new_target)) {
        obj = js_create_from_ctor(ctx, new_target, JS_CLASS_NUMBER);
        if (!JS_IsException(obj))
            JS_SetObjectData(ctx, obj, val);
        return obj;
    } else {
        return val;
    }
}

static bool IsUnaryOp(Value op) { return base::IsInRange(op, ADD, VOID); }

E(T, ADD, "+", 12)
E(T, SUB, "-", 12)
T(NOT, "!", 0)
T(BIT_NOT, "~", 0)
K(DELETE, "delete", 0)
K(TYPEOF, "typeof", 0)
K(VOID, "void", 0)

template <typename Impl>
typename ParserBase<Impl>::ExpressionT
ParserBase<Impl>::ParseUnaryExpression() {
  // UnaryExpression ::
  //   PostfixExpression
  //   'delete' UnaryExpression
  //   'void' UnaryExpression
  //   'typeof' UnaryExpression
  //   '++' UnaryExpression
  //   '--' UnaryExpression
  //   '+' UnaryExpression
  //   '-' UnaryExpression
  //   '~' UnaryExpression
  //   '!' UnaryExpression
  //   [+Await] AwaitExpression[?Yield]

  Token::Value op = peek();
  // 一元运算符处理
  if (Token::IsUnaryOrCountOp(op)) return ParseUnaryOrPrefixExpression();
  if (is_await_allowed() && op == Token::AWAIT) {
// await 处理
    return ParseAwaitExpression();
  }
  return ParsePostfixExpression();
}

template <typename Impl>
typename ParserBase<Impl>::ExpressionT
ParserBase<Impl>::ParseUnaryOrPrefixExpression() {
//...

//...
 // Allow the parser's implementation to rewrite the expression.
   return impl()->BuildUnaryExpression(expression, op, pos);
}

Expression* Parser::BuildUnaryExpression(Expression* expression,
                                         Token::Value op, int pos) {
  DCHECK_NOT_NULL(expression);
  const Literal* literal = expression->AsLiteral();
  if (literal != nullptr) {
// !
    if (op == Token::NOT) {
      // Convert the literal to a boolean condition and negate it.
      return factory()->NewBooleanLiteral(literal->ToBooleanIsFalse(), pos);
    } else if (literal->IsNumberLiteral()) {
      // Compute some expressions involving only number literals.
      double value = literal->AsNumber();
      switch (op) {
    // +
        case Token::ADD:
          return expression;
        // -
        case Token::SUB:
          return factory()->NewNumberLiteral(-value, pos);
        // ~
        case Token::BIT_NOT:
          return factory()->NewNumberLiteral(~DoubleToInt32(value), pos);
        default:
          break;
      }
    }
  }
  return factory()->NewUnaryOperation(op, expression, pos);
}

template <typename LexerType>
template <class TreeBuilder> TreeExpression Parser<LexerType>::parseUnaryExpression(TreeBuilder& context)
{
//... 省略无关代码
 while (tokenStackDepth) {
 switch (tokenType) {
//... 省略无关代码
// ~
case TILDE:
     expr = context.makeBitwiseNotNode(location, expr);
     break;
     // +
case PLUS:
      expr = context.createUnaryPlus(location, expr);
     break;
//... 省略无关代码
}
}
}

ExpressionNode* ASTBuilder::makeBitwiseNotNode(const JSTokenLocation& location, ExpressionNode* expr)
{
if (expr->isNumber())
        return createIntegerLikeNumber(location, ~toInt32(static_cast<NumberNode*>(expr)->value()));
    return new (m_parserArena) BitwiseNotNode(location, expr);
}

inline BitwiseNotNode::BitwiseNotNode(const JSTokenLocation& location, ExpressionNode* expr)
        : UnaryOpNode(location, ResultType::forBitOp(), expr, op_bitnot)
{
}

static constexpr ResultType forBitOp()
{
    return bigIntOrInt32Type();
}

static constexpr ResultType bigIntOrInt32Type()
{
    return ResultType(TypeMaybeBigInt | TypeInt32 | TypeMaybeNumber);
}

/* allowed parse_flags: PF_ARROW_FUNC, PF_POW_ALLOWED, PF_POW_FORBIDDEN */
static __exception int js_parse_unary(JSParseState *s, int parse_flags)
{
    int op;

    switch(s->token.val) {
    case '+':
    case '-':
    case '!':
    case '~':
    case TOK_VOID:
        op = s->token.val;
        if (next_token(s))
            return -1;
        if (js_parse_unary(s, PF_POW_FORBIDDEN))
            return -1;
        switch(op) {
        case '-':
            emit_op(s, OP_neg);
            break;
        case '+':
            emit_op(s, OP_plus);
            break;
        case '!':
            emit_op(s, OP_lnot);
            break;
        case '~':
            emit_op(s, OP_not);
            break;
        case TOK_VOID:
            emit_op(s, OP_drop);
            emit_op(s, OP_undefined);
            break;
        default:
            abort();
        }
        parse_flags = 0;
        break;
//...
}
    //...
    }
}

static void emit_op(JSParseState *s, uint8_t val)
{
    JSFunctionDef *fd = s->cur_func;
    DynBuf *bc = &fd->byte_code;

    /* Use the line number of the last token used, not the next token,
       nor the current offset in the source file.
     */
    if (unlikely(fd->last_opcode_line_num != s->last_line_num)) {
        dbuf_putc(bc, OP_line_num);
        dbuf_put_u32(bc, s->last_line_num);
        fd->last_opcode_line_num = s->last_line_num;
    }
    fd->last_opcode_pos = bc->size;
    dbuf_putc(bc, val);
}

int dbuf_putc(DynBuf *s, uint8_t c)
{
return dbuf_put(s, &c, 1);
}

int dbuf_put(DynBuf *s, const uint8_t *data, size_t len)
{
    if (unlikely((s->size + len) > s->allocated_size)) {
        if (dbuf_realloc(s, s->size + len))
            return -1;
    }
    memcpy(s->buf + s->size, data, len);
    s->size += len;
    return 0;
}

/* argv[] is modified if (flags & JS_CALL_FLAG_COPY_ARGV) = 0. */
static JSValue JS_CallInternal(JSContext *caller_ctx, JSValueConst func_obj,
                               JSValueConst this_obj, JSValueConst new_target,
                               int argc, JSValue *argv, int flags)
{
    JSRuntime *rt = caller_ctx->rt;
    JSContext *ctx;
    JSObject *p;
    JSFunctionBytecode *b;
    JSStackFrame sf_s, *sf = &sf_s;
    const uint8_t *pc;
// ...省略无关代码

for(;;) {
int call_argc;
JSValue *call_argv;
SWITCH(pc) {
// ...
CASE(OP_not):
{
JSValue op1;
op1 = sp[-1];
// 如果是整型
if (JS_VALUE_GET_TAG(op1) == JS_TAG_INT) {
sp[-1] = JS_NewInt32(ctx, ~JS_VALUE_GET_INT(op1));
// 如果不是整型
} else {
if (js_not_slow(ctx, sp))
goto exception;
}
}
BREAK;
// ...
}
// ...
}

static no_inline int js_not_slow(JSContext *ctx, JSValue *sp)
{
    int32_t v1;

    if (unlikely(JS_ToInt32Free(ctx, &v1, sp[-1]))) {
        sp[-1] = JS_UNDEFINED;
        return -1;
    }
    sp[-1] = JS_NewInt32(ctx, ~v1);
    return 0;
}

/* return (<0, 0) in case of exception */
static int JS_ToInt32Free(JSContext *ctx, int32_t *pres, JSValue val)
{
 redo:
tag = JS_VALUE_GET_NORM_TAG(val);
switch(tag) {
case JS_TAG_INT:
case JS_TAG_BOOL:
case JS_TAG_NULL:
case JS_TAG_UNDEFINED:
ret = JS_VALUE_GET_INT(val);
break;
// ...
default:
val = JS_ToNumberFree(ctx, val);
if (JS_IsException(val)) {
*pres = 0;
return -1;
}
goto redo;
}
    *pres = ret;
    return 0;
}

static JSValue JS_ToNumberHintFree(JSContext *ctx, JSValue val,
                                   JSToNumberHintEnum flag)
{
    uint32_t tag;
    JSValue ret;

 redo:
    tag = JS_VALUE_GET_NORM_TAG(val);
    switch(tag) {
    // ...省略无关逻辑
case JS_TAG_STRING:
        {
            const char *str;
            const char *p;
            size_t len;
            
            str = JS_ToCStringLen(ctx, &len, val);
            JS_FreeValue(ctx, val);
            if (!str)
                return JS_EXCEPTION;
            p = str;
            p += skip_spaces(p);
            if ((p - str) == len) {
                ret = JS_NewInt32(ctx, 0);
            } else {
                int flags = ATOD_ACCEPT_BIN_OCT;
                ret = js_atof(ctx, p, &p, 0, flags);
                if (!JS_IsException(ret)) {
                    p += skip_spaces(p);
                    if ((p - str) != len) {
                        JS_FreeValue(ctx, ret);
                        ret = JS_NAN;
                    }
                }
            }
            JS_FreeCString(ctx, str);
        }
        break;
// ...省略无关逻辑
}
// ...省略无关逻辑
}

/* argv[] is modified if (flags & JS_CALL_FLAG_COPY_ARGV) = 0. */
static JSValue JS_CallInternal(JSContext *caller_ctx, JSValueConst func_obj,
                               JSValueConst this_obj, JSValueConst new_target,
                               int argc, JSValue *argv, int flags)
{
    JSRuntime *rt = caller_ctx->rt;
    JSContext *ctx;
    JSObject *p;
    JSFunctionBytecode *b;
    JSStackFrame sf_s, *sf = &sf_s;
    const uint8_t *pc;
// ...省略无关代码

for(;;) {
int call_argc;
JSValue *call_argv;
SWITCH(pc) {
// ...
CASE(OP_plus):
{
    JSValue op1;
uint32_t tag;
op1 = sp[-1];
tag = JS_VALUE_GET_TAG(op1);
if (tag == JS_TAG_INT || JS_TAG_IS_FLOAT64(tag)) {
} else {
if (js_unary_arith_slow(ctx, sp, opcode))
 goto exception;
}
BREAK;
}
// ...省略无关代码
}
}
// ...省略无关代码
}

static no_inline __exception int js_unary_arith_slow(JSContext *ctx, JSValue *sp, OPCodeEnum op)
{
    JSValue op1;
    double d;

    op1 = sp[-1];
    if (unlikely(JS_ToFloat64Free(ctx, &d, op1))) {
        sp[-1] = JS_UNDEFINED;
        return -1;
    }
    switch(op) {
    case OP_inc:
        d++;
        break;
    case OP_dec:
        d--;
        break;
    case OP_plus:
        break;
    case OP_neg:
        d = -d;
        break;
    default:
        abort();
    }
    sp[-1] = JS_NewFloat64(ctx, d);
    return 0;
}