js/src/vm/ObjectFlags.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef vm_ObjectFlags_h
   8 #define vm_ObjectFlags_h
   9
  10 #include <stdint.h>
  11
  12 #include "util/EnumFlags.h"  // js::EnumFlags
  13
  14 namespace js {
  15
  16 // Flags set on the Shape which describe the referring object. Once set these
  17 // cannot be unset (except during object densification of sparse indexes), and
  18 // are transferred from shape to shape as the object's last property changes.
  19 //
  20 // If you add a new flag here, please add appropriate code to JSObject::dump to
  21 // dump it as part of the object representation.
  22 enum class ObjectFlag : uint16_t {
  23   IsUsedAsPrototype = 1 << 0,
  24   NotExtensible = 1 << 1,
  25   Indexed = 1 << 2,
  26   HasInterestingSymbol = 1 << 3,
  27
  28   // If set, the shape's property map may contain an enumerable property. This
  29   // only accounts for (own) shape properties: if the flag is not set, the
  30   // object may still have (enumerable) dense elements, typed array elements, or
  31   // a JSClass enumeration hook.
  32   HasEnumerable = 1 << 4,
  33
  34   FrozenElements = 1 << 5,  // See ObjectElements::FROZEN comment.
  35
  36   // If set, the shape teleporting optimization can no longer be used for
  37   // accessing properties on this object.
  38   // See: JSObject::hasInvalidatedTeleporting, ProtoChainSupportsTeleporting.
  39   InvalidatedTeleporting = 1 << 6,
  40
  41   ImmutablePrototype = 1 << 7,
  42
  43   // See JSObject::isQualifiedVarObj().
  44   QualifiedVarObj = 1 << 8,
  45
  46   // If set, the object may have a non-writable property or an accessor
  47   // property.
  48   //
  49   // * This is only set for PlainObjects because we only need it for these
  50   //   objects and setting it for other objects confuses insertInitialShape.
  51   //
  52   // * This flag does not account for properties named "__proto__". This is
  53   //   because |Object.prototype| has a "__proto__" accessor property and we
  54   //   don't want to include it because it would result in the flag being set on
  55   //   most proto chains. Code using this flag must check for "__proto__"
  56   //   property names separately.
  57   HasNonWritableOrAccessorPropExclProto = 1 << 9,
  58
  59   // If set, the object either mutated or deleted an accessor property. This is
  60   // used to invalidate IC/Warp code specializing on specific getter/setter
  61   // objects. See also the SMDOC comment in vm/GetterSetter.h.
  62   HadGetterSetterChange = 1 << 10,
  63
  64   // If set, use the watchtower testing mechanism to log changes to this object.
  65   UseWatchtowerTestingLog = 1 << 11,
  66
  67   // If set, access to existing properties of this global object can be guarded
  68   // based on a per-global counter that is incremented when the global object
  69   // has its properties reordered/shadowed, instead of a shape guard.
  70   GenerationCountedGlobal = 1 << 12,
  71
  72   // If set, we need to verify the result of a proxy get/set trap.
  73   //
  74   // The [[Get]] and [[Set]] traps for proxy objects enforce certain invariants
  75   // for non-configurable, non-writable data properties and non-configurable
  76   // accessors. If the invariants are not maintained, we must throw a type
  77   // error. If this flag is not set, and this is a NativeObject, *and* the
  78   // class does not have a resolve hook, then this object does not have any
  79   // such properties, and we can skip the slow check.
  80   //
  81   // See
  82   // https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots
  83   NeedsProxyGetSetResultValidation = 1 << 13
  84 };
  85
  86 using ObjectFlags = EnumFlags<ObjectFlag>;
  87
  88 }  // namespace js
  89
  90 #endif /* vm_ObjectFlags_h */