Attachment 294946 Details for Bug 164823 – one possible approach

[patch] one possible approach

blah.patch (text/plain), 5.04 KB, created by Filip Pizlo on 2016-11-16 09:49:58 PST

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Creator: Filip Pizlo

Created: 2016-11-16 09:49:58 PST

Size: 5.04 KB

patch

obsolete

>Index: Source/JavaScriptCore/ChangeLog
>===================================================================
>--- Source/JavaScriptCore/ChangeLog	(revision 208794)
>+++ Source/JavaScriptCore/ChangeLog	(working copy)
>@@ -1,3 +1,25 @@
>+2016-11-16  Filip Pizlo  <fpizlo@apple.com>
>+
>+        Slight Octane regression from concurrent GC's eager object zero-fill
>+        https://bugs.webkit.org/show_bug.cgi?id=164823
>+
>+        Reviewed by NOBODY (OOPS!).
>+        
>+        During concurrent GC, we need to eagerly zero-fill objects we allocate prior to
>+        executing the end-of-allocation fence. This causes some regressions. This is an attempt
>+        to fix those regressions by making them conditional on whether the mutator is fenced.
>+        
>+        This is a slight speed-up on raytrace and boyer.
>+
>+        * ftl/FTLLowerDFGToB3.cpp:
>+        (JSC::FTL::DFG::LowerDFGToB3::compileMaterializeNewObject):
>+        (JSC::FTL::DFG::LowerDFGToB3::splatWordsIfMutatorIsFenced):
>+        (JSC::FTL::DFG::LowerDFGToB3::allocatePropertyStorage):
>+        (JSC::FTL::DFG::LowerDFGToB3::reallocatePropertyStorage):
>+        (JSC::FTL::DFG::LowerDFGToB3::allocateObject):
>+        (JSC::FTL::DFG::LowerDFGToB3::mutatorFence):
>+        (JSC::FTL::DFG::LowerDFGToB3::setButterfly):
>+
> 2016-11-16  Keith Miller  <keith_miller@apple.com>
> 
>         Unreviewed, ARM build fix.
>Index: Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp
>===================================================================
>--- Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp	(revision 208779)
>+++ Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp	(working copy)
>@@ -8134,7 +8134,7 @@ private:
>                 
>                 ValueFromBlock haveButterfly = m_out.anchor(fastButterflyValue);
>                 
>-                splatWords(
>+                splatWordsIfMutatorIsFenced(
>                     fastButterflyValue,
>                     m_out.constInt32(-structure->outOfLineCapacity() - 1),
>                     m_out.constInt32(-1),
>@@ -8960,6 +8960,25 @@ private:
>         splatWords(butterfly, begin, end, hole, heap->atAnyIndex());
>     }
>     
>+    void splatWordsIfMutatorIsFenced(LValue base, LValue begin, LValue end, LValue value, const AbstractHeap& heap)
>+    {
>+        LBasicBlock slowPath = m_out.newBlock();
>+        LBasicBlock continuation = m_out.newBlock();
>+        
>+        LBasicBlock lastNext = m_out.insertNewBlocksBefore(slowPath);
>+        
>+        m_out.branch(
>+            m_out.load8ZeroExt32(m_out.absolute(vm().heap.addressOfMutatorShouldBeFenced())),
>+            rarely(slowPath), usually(continuation));
>+        
>+        m_out.appendTo(slowPath, continuation);
>+        
>+        splatWords(base, begin, end, value, heap);
>+        m_out.jump(continuation);
>+        
>+        m_out.appendTo(continuation, lastNext);
>+    }
>+    
>     void splatWords(LValue base, LValue begin, LValue end, LValue value, const AbstractHeap& heap)
>     {
>         const uint64_t unrollingLimit = 10;
>@@ -9013,7 +9032,7 @@ private:
>         
>         LValue result = allocatePropertyStorageWithSizeImpl(initialOutOfLineCapacity);
> 
>-        splatWords(
>+        splatWordsIfMutatorIsFenced(
>             result,
>             m_out.constInt32(-initialOutOfLineCapacity - 1), m_out.constInt32(-1),
>             m_out.int64Zero, m_heaps.properties.atAnyNumber());
>@@ -9046,7 +9065,7 @@ private:
>             m_out.storePtr(loaded, m_out.address(m_heaps.properties.atAnyNumber(), result, offset));
>         }
>         
>-        splatWords(
>+        splatWordsIfMutatorIsFenced(
>             result,
>             m_out.constInt32(-newSize - 1), m_out.constInt32(-oldSize - 1),
>             m_out.int64Zero, m_heaps.properties.atAnyNumber());
>@@ -9926,7 +9945,7 @@ private:
>         LValue allocator, Structure* structure, LValue butterfly, LBasicBlock slowPath)
>     {
>         LValue result = allocateCell(allocator, structure, slowPath);
>-        splatWords(
>+        splatWordsIfMutatorIsFenced(
>             result,
>             m_out.constInt32(JSFinalObject::offsetOfInlineStorage() / 8),
>             m_out.constInt32(JSFinalObject::offsetOfInlineStorage() / 8 + structure->inlineCapacity()),
>@@ -12585,7 +12604,7 @@ private:
>             m_out.load8ZeroExt32(m_out.absolute(vm().heap.addressOfMutatorShouldBeFenced())),
>             rarely(slowPath), usually(continuation));
>         
>-        m_out.appendTo(slowPath);
>+        m_out.appendTo(slowPath, continuation);
>         
>         m_out.fence(&m_heaps.root, nullptr);
>         m_out.jump(continuation);
>@@ -12612,12 +12631,12 @@ private:
>             m_out.load8ZeroExt32(m_out.absolute(vm().heap.addressOfMutatorShouldBeFenced())),
>             rarely(slowPath), usually(fastPath));
> 
>-        m_out.appendTo(fastPath);
>+        m_out.appendTo(fastPath, slowPath);
>         
>         m_out.storePtr(butterfly, object, m_heaps.JSObject_butterfly);
>         m_out.jump(continuation);
>         
>-        m_out.appendTo(slowPath);
>+        m_out.appendTo(slowPath, continuation);
>         
>         m_out.fence(&m_heaps.root, nullptr);
>         m_out.storePtr(butterfly, object, m_heaps.JSObject_butterfly);

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