Changeset 184666 in webkit

Timestamp:

May 20, 2015, 3:25:20 PM (10 years ago)

Author:

akling@apple.com

Message:

Remove unused MarkedBlock::m_rememberedSet.
<​https://webkit.org/b/145224>

Reviewed by Mark Hahnenberg.

The MarkedBlock had a copy of the remembered bit for each of its cells,
and we were maintaining that bitmap despite no one actually ever consulting it.

This patch removes MarkedBlock::m_rememberedSet, freeing up 128 bytes in each
block and making write barriers a little faster.

• heap/Heap.cpp:

(JSC::Heap::clearRememberedSet):
(JSC::Heap::addToRememberedSet):

• heap/HeapInlines.h:

(JSC::Heap::isRemembered):

• heap/MarkedBlock.cpp:

(JSC::MarkedBlock::clearRememberedSet): Deleted.
(JSC::MarkedBlock::clearMarksWithCollectionType):

• heap/MarkedBlock.h:

(JSC::MarkedBlock::setRemembered): Deleted.
(JSC::MarkedBlock::clearRemembered): Deleted.
(JSC::MarkedBlock::atomicClearRemembered): Deleted.
(JSC::MarkedBlock::isRemembered): Deleted.

• heap/MarkedSpace.h:

(JSC::ClearRememberedSet::operator()): Deleted.
(JSC::MarkedSpace::clearRememberedSet): Deleted.

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• heap/Heap.cpp (modified) (2 diffs)
• heap/HeapInlines.h (modified) (1 diff)
• heap/MarkedBlock.cpp (modified) (2 diffs)
• heap/MarkedBlock.h (modified) (3 diffs)
• heap/MarkedSpace.h (modified) (3 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2015-05-20  Andreas Kling  <akling@apple.com>
+
+        Remove unused MarkedBlock::m_rememberedSet.
+        <https://webkit.org/b/145224>
+
+        Reviewed by Mark Hahnenberg.
+
+        The MarkedBlock had a copy of the remembered bit for each of its cells,
+        and we were maintaining that bitmap despite no one actually ever consulting it.
+
+        This patch removes MarkedBlock::m_rememberedSet, freeing up 128 bytes in each
+        block and making write barriers a little faster.
+
+        * heap/Heap.cpp:
+        (JSC::Heap::clearRememberedSet):
+        (JSC::Heap::addToRememberedSet):
+        * heap/HeapInlines.h:
+        (JSC::Heap::isRemembered):
+        * heap/MarkedBlock.cpp:
+        (JSC::MarkedBlock::clearRememberedSet): Deleted.
+        (JSC::MarkedBlock::clearMarksWithCollectionType):
+        * heap/MarkedBlock.h:
+        (JSC::MarkedBlock::setRemembered): Deleted.
+        (JSC::MarkedBlock::clearRemembered): Deleted.
+        (JSC::MarkedBlock::atomicClearRemembered): Deleted.
+        (JSC::MarkedBlock::isRemembered): Deleted.
+        * heap/MarkedSpace.h:
+        (JSC::ClearRememberedSet::operator()): Deleted.
+        (JSC::MarkedSpace::clearRememberedSet): Deleted.
+
 2015-05-20  Andreas Kling  <akling@apple.com>
 

trunk/Source/JavaScriptCore/heap/Heap.cpp

@@ -799 +799 @@
 #if ENABLE(GGC)
     GCPHASE(ClearRememberedSet);
-    for (auto* cell : rememberedSet) {
-        MarkedBlock::blockFor(cell)->clearRemembered(cell);
+    for (auto* cell : rememberedSet)
         const_cast<JSCell*>(cell)->setRemembered(false);
-    }
 #else
     UNUSED_PARAM(rememberedSet);
@@ -976 +974 @@
     if (isRemembered(cell))
         return;
-    MarkedBlock::blockFor(cell)->setRemembered(cell);
     const_cast<JSCell*>(cell)->setRemembered(true);
     m_slotVisitor.unconditionallyAppend(const_cast<JSCell*>(cell));

trunk/Source/JavaScriptCore/heap/HeapInlines.h

@@ -76 +76 @@
     ASSERT(cell);
     ASSERT(!Options::enableConcurrentJIT() || !isCompilationThread());
-    ASSERT(MarkedBlock::blockFor(cell)->isRemembered(cell) == cell->isRemembered());
     return cell->isRemembered();
 }

trunk/Source/JavaScriptCore/heap/MarkedBlock.cpp

@@ -219 +219 @@
 }
 
-void MarkedBlock::clearRememberedSet()
-{
-    m_rememberedSet.clearAll();
-}
-
 template <HeapOperation collectionType>
 void MarkedBlock::clearMarksWithCollectionType()
@@ -233 +228 @@
     if (collectionType == FullCollection) {
         m_marks.clearAll();
-#if ENABLE(GGC)
-        m_rememberedSet.clearAll();
-#endif
         // This will become true at the end of the mark phase. We set it now to
         // avoid an extra pass to do so later.

trunk/Source/JavaScriptCore/heap/MarkedBlock.h

@@ -148 +148 @@
         bool clearNewlyAllocated();
         void clearMarks();
-        void clearRememberedSet();
         template <HeapOperation collectionType>
         void clearMarksWithCollectionType();
@@ -210 +209 @@
 #if ENABLE(PARALLEL_GC)
         WTF::Bitmap<atomsPerBlock, WTF::BitmapAtomic, uint8_t> m_marks;
-        WTF::Bitmap<atomsPerBlock, WTF::BitmapAtomic, uint8_t> m_rememberedSet;
 #else
         WTF::Bitmap<atomsPerBlock, WTF::BitmapNotAtomic, uint8_t> m_marks;
-        WTF::Bitmap<atomsPerBlock, WTF::BitmapNotAtomic, uint8_t> m_rememberedSet;
 #endif
         std::unique_ptr<WTF::Bitmap<atomsPerBlock>> m_newlyAllocated;
@@ -346 +343 @@
     {
         return (reinterpret_cast<Bits>(p) - reinterpret_cast<Bits>(this)) / atomSize;
-    }
-
-    inline void MarkedBlock::setRemembered(const void* p)
-    {
-        m_rememberedSet.set(atomNumber(p));
-    }
-
-    inline void MarkedBlock::clearRemembered(const void* p)
-    {
-        m_rememberedSet.clear(atomNumber(p));
-    }
-
-    inline void MarkedBlock::atomicClearRemembered(const void* p)
-    {
-        m_rememberedSet.concurrentTestAndClear(atomNumber(p));
-    }
-
-    inline bool MarkedBlock::isRemembered(const void* p)
-    {
-        return m_rememberedSet.get(atomNumber(p));
     }
 

trunk/Source/JavaScriptCore/heap/MarkedSpace.h

@@ -49 +49 @@
     {
         block->clearMarks();
-    }
-};
-
-struct ClearRememberedSet : MarkedBlock::VoidFunctor {
-    void operator()(MarkedBlock* block)
-    {
-        block->clearRememberedSet();
     }
 };
@@ -143 +136 @@
 
     void clearMarks();
-    void clearRememberedSet();
     void clearNewlyAllocated();
     void sweep();
@@ -278 +270 @@
 }
 
-inline void MarkedSpace::clearRememberedSet()
-{
-    forEachBlock<ClearRememberedSet>();
-}
-
 inline size_t MarkedSpace::objectCount()
 {