Bug 268703 – Every Timer objects wastes 7 bytes for padding

• Component: DOM
• Status: RESOLVED FIXED

[Ryosuke Niwa]

Because of bool m_hasReachedMaxNestingLevel, each Timer class wastes 7 bytes for padding:

  +0 < 64> WebCore::Timer
  +0 < 56>     WebCore::TimerBase WebCore::TimerBase
  +0 <  8>         __vtbl_ptr_type * _vptr
  +8 <  8>         WTF::WeakPtr<WebCore::TimerAlignment, WTF::DefaultWeakPtrImpl, WTF::RawPtrTraits<WTF::DefaultWeakPtrImpl> > m_alignment
  +8 <  8>             WTF::RefPtr<WTF::DefaultWeakPtrImpl, WTF::RawPtrTraits<WTF::DefaultWeakPtrImpl>, WTF::DefaultRefDerefTraits<WTF::DefaultWeakPtrImpl> > m_impl
  +8 <  8>                 WTF::RawPtrTraits<WTF::DefaultWeakPtrImpl>::StorageType m_ptr
 +16 <  8>         WTF::MonotonicTime m_unalignedNextFireTime
 +16 <  8>             WTF::GenericTimeMixin<WTF::MonotonicTime> WTF::GenericTimeMixin<WTF::MonotonicTime>
 +16 <  8>                 double m_value
 +24 <  8>         WTF::Seconds m_repeatInterval
 +24 <  8>             double m_value
 +32 <  1>         bool m_hasReachedMaxNestingLevel
 +33 <  7>         <PADDING: 7 bytes>
 +40 <  8>         WTF::RefPtr<WebCore::ThreadTimerHeapItem, WTF::RawPtrTraits<WebCore::ThreadTimerHeapItem>, WTF::DefaultRefDerefTraits<WebCore::ThreadTimerHeapItem> > m_heapItem
 +40 <  8>             WTF::RawPtrTraits<WebCore::ThreadTimerHeapItem>::StorageType m_ptr
 +48 <  8>         WTF::Ref<WTF::Thread, WTF::RawPtrTraits<WTF::Thread> > m_thread
 +48 <  8>             WTF::RawPtrTraits<WTF::Thread>::StorageType m_ptr
 +56 <  8>     WTF::Function<void ()> m_function
 +56 <  8>         std::__1::unique_ptr<WTF::Detail::CallableWrapperBase<void>, std::__1::default_delete<WTF::Detail::CallableWrapperBase<void> > > m_callableWrapper
 +56 <  8>             std::__1::__compressed_pair<WTF::Detail::CallableWrapperBase<void> *, std::__1::default_delete<WTF::Detail::CallableWrapperBase<void> > > __ptr_
 +56 <  8>                 std::__1::__compressed_pair_elem<WTF::Detail::CallableWrapperBase<void> *, 0, false> std::__1::__compressed_pair_elem<WTF::Detail::CallableWrapperBase<void> *, 0, false>
 +56 <  8>                     WTF::Detail::CallableWrapperBase<void> * __value_
 +56 <  1>                 std::__1::__compressed_pair_elem<std::__1::default_delete<WTF::Detail::CallableWrapperBase<void> >, 1, true> std::__1::__compressed_pair_elem<std::__1::default_delete<WTF::Detail::CallableWrapperBase<void> >, 1, true>
 +56 <  1>                     std::__1::default_delete<WTF::Detail::CallableWrapperBase<void> > std::__1::default_delete<WTF::Detail::CallableWrapperBase<void> >
Total byte size: 64
Total pad bytes: 7

[Ryosuke Niwa]

Pull request: https://github.com/WebKit/WebKit/pull/23822

[EWS]

Committed 274077@main (c2eedea2d530): <https://commits.webkit.org/274077@main>

Reviewed commits have been landed. Closing PR #23822 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/122280493>