Make WebCore::Timer more space-efficient

https://bugs.webkit.org/show_bug.cgi?id=187455

Reviewed by Brent Fulgham.

Steal a bit from m_heapIndex for m_wasDeleted to eliminate padding in Timer.
This reduces the size of Document, which has 8 Timers, from 3360 to 3296 bytes (saving 64 bytes).

* platform/Timer.cpp:
(WebCore::TimerBase::TimerBase):
* platform/Timer.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@234581 268f45cc-cd09-0410-ab3c-d52691b4dbfc

diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index 4524d42..9149485 100644 (file)
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,17 @@
+2018-08-04  Simon Fraser  <simon.fraser@apple.com>
+
+        Make WebCore::Timer more space-efficient
+        https://bugs.webkit.org/show_bug.cgi?id=187455
+
+        Reviewed by Brent Fulgham.
+
+        Steal a bit from m_heapIndex for m_wasDeleted to eliminate padding in Timer.
+        This reduces the size of Document, which has 8 Timers, from 3360 to 3296 bytes (saving 64 bytes).
+
+        * platform/Timer.cpp:
+        (WebCore::TimerBase::TimerBase):
+        * platform/Timer.h:
+
 2018-08-04  Ryosuke Niwa  <rniwa@webkit.org>
 
         Properties set on window.customElements can disappear due to GC

diff --git a/Source/WebCore/platform/Timer.cpp b/Source/WebCore/platform/Timer.cpp
index 5706c2e..722d453 100644 (file)
--- a/Source/WebCore/platform/Timer.cpp
+++ b/Source/WebCore/platform/Timer.cpp
@@ -185,6 +185,8 @@ inline bool TimerHeapLessThanFunction::operator()(const TimerBase* a, const Time
 // ----------------
 
 TimerBase::TimerBase()
+    : m_heapIndex(-1)
+    , m_wasDeleted(false)
 {
 }
 

diff --git a/Source/WebCore/platform/Timer.h b/Source/WebCore/platform/Timer.h
index 524d486..ec90b86 100644 (file)
--- a/Source/WebCore/platform/Timer.h
+++ b/Source/WebCore/platform/Timer.h
@@ -98,9 +98,9 @@ private:
     MonotonicTime m_nextFireTime; // 0 if inactive
     MonotonicTime m_unalignedNextFireTime; // m_nextFireTime not considering alignment interval
     Seconds m_repeatInterval; // 0 if not repeating
-    int m_heapIndex { -1 }; // -1 if not in heap
+    signed int m_heapIndex : 31; // -1 if not in heap
+    bool m_wasDeleted : 1;
     unsigned m_heapInsertionOrder; // Used to keep order among equal-fire-time timers
-    bool m_wasDeleted { false };
     Vector<TimerBase*>* m_cachedThreadGlobalTimerHeap { nullptr };
 
     Ref<Thread> m_thread { Thread::current() };