xpcom/ds/nsTArray.cpp

   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 #include <string.h>
   8 #include "nsTArray.h"
   9 #include "nsXPCOM.h"
  10 #include "nsCycleCollectionNoteChild.h"
  11 #include "nsDebug.h"
  12 #include "mozilla/CheckedInt.h"
  13 #include "mozilla/IntegerPrintfMacros.h"
  14
  15 // Ensure this is sufficiently aligned so that Elements() and co don't create
  16 // unaligned pointers, or slices with unaligned pointers for empty arrays, see
  17 // https://github.com/servo/servo/issues/22613.
  18 alignas(8) const nsTArrayHeader sEmptyTArrayHeader = {0, 0, 0};
  19
  20 bool IsTwiceTheRequiredBytesRepresentableAsUint32(size_t aCapacity,
  21                                                   size_t aElemSize) {
  22   using mozilla::CheckedUint32;
  23   return ((CheckedUint32(aCapacity) * aElemSize) * 2).isValid();
  24 }
  25
  26 void ::detail::SetCycleCollectionArrayFlag(uint32_t& aFlags) {
  27   aFlags |= CycleCollectionEdgeNameArrayFlag;
  28 }