forked from mirrors/gecko-dev
989d33f031
Until now we used our own, well-aged C-style implementation of quick sort, based on code from 1992/93. Apart from being old (which is not bad as such), this code had some disadvantages, namely: - It was not typesafe and invocations could not be optimized by inlining. - [Quick Sort](https://en.wikipedia.org/wiki/Quicksort) has a worst case performance of O(n<sup>2</sup>). - Quick Sort can recurse deeply and thus cause stack overflows. - On Windows, [Control Flow Guard](https://learn.microsoft.com/en-us/windows/win32/secbp/control-flow-guard) inspects any function invocation via function pointers to check if the called function was known at compile time. This comes with a [notable overhead](https://bugzilla.mozilla.org/show_bug.cgi?id=1842079) when calling the compare function repeatedly. `std::sort` and `std::stable_sort` are preferred and have an optimal, guaranteed worst case performance. Differential Revision: https://phabricator.services.mozilla.com/D181339
27 lines
1.1 KiB
C++
27 lines
1.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsTArray.h"
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#include "nsXPCOM.h"
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#include "nsCycleCollectionNoteChild.h"
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#include "nsDebug.h"
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#include "mozilla/CheckedInt.h"
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#include "mozilla/IntegerPrintfMacros.h"
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// Ensure this is sufficiently aligned so that Elements() and co don't create
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// unaligned pointers, or slices with unaligned pointers for empty arrays, see
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// https://github.com/servo/servo/issues/22613.
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alignas(8) const nsTArrayHeader sEmptyTArrayHeader = {0, 0, 0};
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bool IsTwiceTheRequiredBytesRepresentableAsUint32(size_t aCapacity,
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size_t aElemSize) {
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using mozilla::CheckedUint32;
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return ((CheckedUint32(aCapacity) * aElemSize) * 2).isValid();
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}
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void ::detail::SetCycleCollectionArrayFlag(uint32_t& aFlags) {
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aFlags |= CycleCollectionEdgeNameArrayFlag;
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}
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