Title: [210662] branches/safari-603-branch/Source/_javascript_Core

Diff

Modified: branches/safari-603-branch/Source/_javascript_Core/CMakeLists.txt (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/CMakeLists.txt	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/CMakeLists.txt	2017-01-12 16:46:18 UTC (rev 210662)
@@ -510,7 +510,6 @@
     heap/WeakBlock.cpp
     heap/WeakHandleOwner.cpp
     heap/WeakSet.cpp
-    heap/WriteBarrierBuffer.cpp
     heap/WriteBarrierSupport.cpp
 
     inspector/ConsoleMessage.cpp

Modified: branches/safari-603-branch/Source/_javascript_Core/ChangeLog (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/ChangeLog	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/ChangeLog	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,53 @@
 2017-01-12  Matthew Hanson  <matthew_han...@apple.com>
 
+        Merge r210565. rdar://problem/29942167
+
+    2017-01-09  Filip Pizlo  <fpi...@apple.com>
+
+            Streamline the GC barrier slowpath
+            https://bugs.webkit.org/show_bug.cgi?id=166878
+
+            Reviewed by Geoffrey Garen and Saam Barati.
+
+            This implements two optimizations to the barrier:
+
+            - Removes the write barrier buffer. This was just overhead.
+
+            - Teaches the slow path how to white an object that was black but unmarked, ensuring that
+              we don't take slow path for this object again.
+
+            * _javascript_Core.xcodeproj/project.pbxproj:
+            * dfg/DFGSpeculativeJIT.cpp:
+            (JSC::DFG::SpeculativeJIT::compileStoreBarrier):
+            * ftl/FTLLowerDFGToB3.cpp:
+            (JSC::FTL::DFG::LowerDFGToB3::emitStoreBarrier):
+            * heap/CellState.h:
+            * heap/Heap.cpp:
+            (JSC::Heap::Heap):
+            (JSC::Heap::markToFixpoint):
+            (JSC::Heap::addToRememberedSet):
+            (JSC::Heap::stopTheWorld):
+            (JSC::Heap::writeBarrierSlowPath):
+            (JSC::Heap::buildConstraintSet):
+            (JSC::Heap::flushWriteBarrierBuffer): Deleted.
+            * heap/Heap.h:
+            (JSC::Heap::writeBarrierBuffer): Deleted.
+            * heap/SlotVisitor.cpp:
+            (JSC::SlotVisitor::appendJSCellOrAuxiliary):
+            (JSC::SlotVisitor::setMarkedAndAppendToMarkStack):
+            (JSC::SlotVisitor::appendToMarkStack):
+            (JSC::SlotVisitor::visitChildren):
+            * heap/WriteBarrierBuffer.cpp: Removed.
+            * heap/WriteBarrierBuffer.h: Removed.
+            * jit/JITOperations.cpp:
+            * jit/JITOperations.h:
+            * runtime/JSCellInlines.h:
+            (JSC::JSCell::JSCell):
+            * runtime/StructureIDBlob.h:
+            (JSC::StructureIDBlob::StructureIDBlob):
+
+2017-01-12  Matthew Hanson  <matthew_han...@apple.com>
+
         Merge r210563. rdar://problem/29940224
 
     2017-01-10  Mark Lam  <mark....@apple.com>

Modified: branches/safari-603-branch/Source/_javascript_Core/_javascript_Core.xcodeproj/project.pbxproj (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/_javascript_Core.xcodeproj/project.pbxproj	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/_javascript_Core.xcodeproj/project.pbxproj	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1230,8 +1230,6 @@
 		2A111246192FCE79005EE18D /* CustomGetterSetter.h in Headers */ = {isa = PBXBuildFile; fileRef = 2A111244192FCE79005EE18D /* CustomGetterSetter.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		2A48D1911772365B00C65A5F /* APICallbackFunction.h in Headers */ = {isa = PBXBuildFile; fileRef = C211B574176A224D000E2A23 /* APICallbackFunction.h */; };
 		2A4BB7F318A41179008A0FCD /* JSManagedValueInternal.h in Headers */ = {isa = PBXBuildFile; fileRef = 2A4BB7F218A41179008A0FCD /* JSManagedValueInternal.h */; };
-		2A4EC90B1860D6C20094F782 /* WriteBarrierBuffer.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 2A4EC9091860D6C20094F782 /* WriteBarrierBuffer.cpp */; };
-		2A4EC90C1860D6C20094F782 /* WriteBarrierBuffer.h in Headers */ = {isa = PBXBuildFile; fileRef = 2A4EC90A1860D6C20094F782 /* WriteBarrierBuffer.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		2A7A58EF1808A4C40020BDF7 /* DeferGC.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 2A7A58EE1808A4C40020BDF7 /* DeferGC.cpp */; };
 		2A83638518D7D0EE0000EBCC /* EdenGCActivityCallback.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 2A83638318D7D0EE0000EBCC /* EdenGCActivityCallback.cpp */; };
 		2A83638618D7D0EE0000EBCC /* EdenGCActivityCallback.h in Headers */ = {isa = PBXBuildFile; fileRef = 2A83638418D7D0EE0000EBCC /* EdenGCActivityCallback.h */; settings = {ATTRIBUTES = (Private, ); }; };
@@ -3629,8 +3627,6 @@
 		2A343F7418A1748B0039B085 /* GCSegmentedArray.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GCSegmentedArray.h; sourceTree = "<group>"; };
 		2A343F7718A1749D0039B085 /* GCSegmentedArrayInlines.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GCSegmentedArrayInlines.h; sourceTree = "<group>"; };
 		2A4BB7F218A41179008A0FCD /* JSManagedValueInternal.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = JSManagedValueInternal.h; sourceTree = "<group>"; };
-		2A4EC9091860D6C20094F782 /* WriteBarrierBuffer.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = WriteBarrierBuffer.cpp; sourceTree = "<group>"; };
-		2A4EC90A1860D6C20094F782 /* WriteBarrierBuffer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WriteBarrierBuffer.h; sourceTree = "<group>"; };
 		2A7A58EE1808A4C40020BDF7 /* DeferGC.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = DeferGC.cpp; sourceTree = "<group>"; };
 		2A83638318D7D0EE0000EBCC /* EdenGCActivityCallback.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = EdenGCActivityCallback.cpp; sourceTree = "<group>"; };
 		2A83638418D7D0EE0000EBCC /* EdenGCActivityCallback.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = EdenGCActivityCallback.h; sourceTree = "<group>"; };
@@ -5798,8 +5794,6 @@
 				14E84F9B14EE1ACC00D6D5D4 /* WeakSet.cpp */,
 				14E84F9C14EE1ACC00D6D5D4 /* WeakSet.h */,
 				14150132154BB13F005D8C98 /* WeakSetInlines.h */,
-				2A4EC9091860D6C20094F782 /* WriteBarrierBuffer.cpp */,
-				2A4EC90A1860D6C20094F782 /* WriteBarrierBuffer.h */,
 				0FC8150814043BCA00CFA603 /* WriteBarrierSupport.cpp */,
 				0FC8150914043BD200CFA603 /* WriteBarrierSupport.h */,
 			);
@@ -9076,7 +9070,6 @@
 				ADBC54D51DF8EA2B005BF738 /* WebAssemblyToJSCallee.h in Headers */,
 				BC18C47A0E16F5CD00B34460 /* WebKitAvailability.h in Headers */,
 				A7DCB97312E5193F00911940 /* WriteBarrier.h in Headers */,
-				2A4EC90C1860D6C20094F782 /* WriteBarrierBuffer.h in Headers */,
 				C2B6D75318A33793004A9301 /* WriteBarrierInlines.h in Headers */,
 				0FC8150A14043BF500CFA603 /* WriteBarrierSupport.h in Headers */,
 				9688CB160ED12B4E001D649F /* X86Assembler.h in Headers */,
@@ -10461,7 +10454,6 @@
 				AD2FCBFC1DB58DAD00B3E736 /* WebAssemblyTableConstructor.cpp in Sources */,
 				AD2FCBFE1DB58DAD00B3E736 /* WebAssemblyTablePrototype.cpp in Sources */,
 				ADBC54D41DF8EA2B005BF738 /* WebAssemblyToJSCallee.cpp in Sources */,
-				2A4EC90B1860D6C20094F782 /* WriteBarrierBuffer.cpp in Sources */,
 				0FC8150B14043C0E00CFA603 /* WriteBarrierSupport.cpp in Sources */,
 				A7E5AB3A1799E4B200D2833D /* X86Disassembler.cpp in Sources */,
 				863C6D9C1521111A00585E4E /* YarrCanonicalizeUCS2.cpp in Sources */,

Modified: branches/safari-603-branch/Source/_javascript_Core/dfg/DFGSpeculativeJIT.cpp (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/dfg/DFGSpeculativeJIT.cpp	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/dfg/DFGSpeculativeJIT.cpp	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2011-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -60,7 +60,6 @@
 #include "RegExpConstructor.h"
 #include "ScopedArguments.h"
 #include "ScratchRegisterAllocator.h"
-#include "WriteBarrierBuffer.h"
 #include <wtf/BitVector.h>
 #include <wtf/Box.h>
 #include <wtf/MathExtras.h>
@@ -8906,11 +8905,9 @@
     
     SpeculateCellOperand base(this, node->child1());
     GPRTemporary scratch1(this);
-    GPRTemporary scratch2(this);
     
     GPRReg baseGPR = base.gpr();
     GPRReg scratch1GPR = scratch1.gpr();
-    GPRReg scratch2GPR = scratch2.gpr();
     
     JITCompiler::JumpList ok;
     
@@ -8924,22 +8921,8 @@
     } else
         ok.append(m_jit.barrierBranchWithoutFence(baseGPR));
 
-    WriteBarrierBuffer& writeBarrierBuffer = m_jit.vm()->heap.m_writeBarrierBuffer;
-    m_jit.load32(writeBarrierBuffer.currentIndexAddress(), scratch2GPR);
-    JITCompiler::Jump needToFlush = m_jit.branch32(MacroAssembler::AboveOrEqual, scratch2GPR, MacroAssembler::TrustedImm32(writeBarrierBuffer.capacity()));
-
-    m_jit.add32(TrustedImm32(1), scratch2GPR);
-    m_jit.store32(scratch2GPR, writeBarrierBuffer.currentIndexAddress());
-
-    m_jit.move(TrustedImmPtr(writeBarrierBuffer.buffer()), scratch1GPR);
-    // We use an offset of -sizeof(void*) because we already added 1 to scratch2.
-    m_jit.storePtr(baseGPR, MacroAssembler::BaseIndex(scratch1GPR, scratch2GPR, MacroAssembler::ScalePtr, static_cast<int32_t>(-sizeof(void*))));
-
-    ok.append(m_jit.jump());
-    needToFlush.link(&m_jit);
-
     silentSpillAllRegisters(InvalidGPRReg);
-    callOperation(operationFlushWriteBarrierBuffer, baseGPR);
+    callOperation(operationWriteBarrierSlowPath, baseGPR);
     silentFillAllRegisters(InvalidGPRReg);
 
     ok.link(&m_jit);

Modified: branches/safari-603-branch/Source/_javascript_Core/ftl/FTLLowerDFGToB3.cpp (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/ftl/FTLLowerDFGToB3.cpp	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/ftl/FTLLowerDFGToB3.cpp	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2013-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -12959,8 +12959,13 @@
 
     void emitStoreBarrier(LValue base, bool isFenced)
     {
+        LBasicBlock recheckPath = nullptr;
+        if (isFenced)
+            recheckPath = m_out.newBlock();
         LBasicBlock slowPath = m_out.newBlock();
         LBasicBlock continuation = m_out.newBlock();
+        
+        LBasicBlock lastNext = m_out.insertNewBlocksBefore(isFenced ? recheckPath : slowPath);
 
         LValue threshold;
         if (isFenced)
@@ -12970,76 +12975,23 @@
         
         m_out.branch(
             m_out.above(loadCellState(base), threshold),
-            usually(continuation), rarely(slowPath));
-
-        LBasicBlock lastNext = m_out.appendTo(slowPath, continuation);
+            usually(continuation), rarely(isFenced ? recheckPath : slowPath));
         
-        // We emit the store barrier slow path lazily. In a lot of cases, this will never fire. And
-        // when it does fire, it makes sense for us to generate this code using our JIT rather than
-        // wasting B3's time optimizing it.
-        PatchpointValue* patchpoint = lazySlowPath(
-            [=] (const Vector<Location>& locations) -> RefPtr<LazySlowPath::Generator> {
-                GPRReg baseGPR = locations[1].directGPR();
+        if (isFenced) {
+            m_out.appendTo(recheckPath, slowPath);
+            
+            m_out.fence(&m_heaps.root, &m_heaps.JSCell_cellState);
+            
+            m_out.branch(
+                m_out.above(loadCellState(base), m_out.constInt32(blackThreshold)),
+                usually(continuation), rarely(slowPath));
+        }
 
-                return LazySlowPath::createGenerator(
-                    [=] (CCallHelpers& jit, LazySlowPath::GenerationParams& params) {
-                        if (isFenced) {
-                            CCallHelpers::Jump noFence = jit.jumpIfMutatorFenceNotNeeded();
-                            jit.memoryFence();
-                            params.doneJumps.append(jit.barrierBranchWithoutFence(baseGPR));
-                            noFence.link(&jit);
-                        }
-                        
-                        RegisterSet usedRegisters = params.lazySlowPath->usedRegisters();
-                        ScratchRegisterAllocator scratchRegisterAllocator(usedRegisters);
-                        scratchRegisterAllocator.lock(baseGPR);
-
-                        GPRReg scratch1 = scratchRegisterAllocator.allocateScratchGPR();
-                        GPRReg scratch2 = scratchRegisterAllocator.allocateScratchGPR();
-
-                        ScratchRegisterAllocator::PreservedState preservedState =
-                            scratchRegisterAllocator.preserveReusedRegistersByPushing(jit, ScratchRegisterAllocator::ExtraStackSpace::SpaceForCCall);
-
-                        // We've already saved these, so when we make a slow path call, we don't have
-                        // to save them again.
-                        usedRegisters.exclude(RegisterSet(scratch1, scratch2));
-
-                        WriteBarrierBuffer& writeBarrierBuffer = jit.vm()->heap.writeBarrierBuffer();
-                        jit.load32(writeBarrierBuffer.currentIndexAddress(), scratch2);
-                        CCallHelpers::Jump needToFlush = jit.branch32(
-                            CCallHelpers::AboveOrEqual, scratch2,
-                            CCallHelpers::TrustedImm32(writeBarrierBuffer.capacity()));
-
-                        jit.add32(CCallHelpers::TrustedImm32(1), scratch2);
-                        jit.store32(scratch2, writeBarrierBuffer.currentIndexAddress());
-
-                        jit.move(CCallHelpers::TrustedImmPtr(writeBarrierBuffer.buffer()), scratch1);
-                        jit.storePtr(
-                            baseGPR,
-                            CCallHelpers::BaseIndex(
-                                scratch1, scratch2, CCallHelpers::ScalePtr,
-                                static_cast<int32_t>(-sizeof(void*))));
-
-                        scratchRegisterAllocator.restoreReusedRegistersByPopping(jit, preservedState);
-
-                        params.doneJumps.append(jit.jump());
-
-                        needToFlush.link(&jit);
-                        callOperation(
-                            usedRegisters, jit, params.lazySlowPath->callSiteIndex(),
-                            params.exceptionJumps, operationFlushWriteBarrierBuffer, InvalidGPRReg,
-                            baseGPR);
-                        scratchRegisterAllocator.restoreReusedRegistersByPopping(jit, preservedState);
-                        params.doneJumps.append(jit.jump());
-                    });
-            },
-            base);
+        m_out.appendTo(slowPath, continuation);
         
-        if (isFenced)
-            m_heaps.decoratePatchpointRead(&m_heaps.root, patchpoint);
-        else
-            m_heaps.decoratePatchpointRead(&m_heaps.JSCell_cellState, patchpoint);
-        m_heaps.decoratePatchpointWrite(&m_heaps.JSCell_cellState, patchpoint);
+        LValue call = vmCall(Void, m_out.operation(operationWriteBarrierSlowPath), m_callFrame, base);
+        m_heaps.decorateCCallRead(&m_heaps.root, call);
+        m_heaps.decorateCCallWrite(&m_heaps.JSCell_cellState, call);
         
         m_out.jump(continuation);
 

Modified: branches/safari-603-branch/Source/_javascript_Core/heap/CellState.h (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/heap/CellState.h	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/heap/CellState.h	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2015-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -29,17 +29,20 @@
 
 namespace JSC {
 
+// The CellState of a cell is a kind of hint about what the state of the cell is.
 enum class CellState : uint8_t {
     // The object is either currently being scanned, or it has finished being scanned, or this
     // is a full collection and it's actually a white object (you'd know because its mark bit
     // would be clear).
-    PossiblyOldOrBlack = 0,
+    PossiblyBlack = 0,
     
     // The object is in eden. During GC, this means that the object has not been marked yet.
-    DefinitelyNewAndWhite = 1,
+    DefinitelyWhite = 1,
 
-    // The object is grey - i.e. it will be scanned.
-    DefinitelyGrey = 2,
+    // This sorta means that the object is grey - i.e. it will be scanned. Or it could be white
+    // during a full collection if its mark bit is clear. That would happen if it had been black,
+    // got barriered, and we did a full collection.
+    PossiblyGrey = 2
 };
 
 static const unsigned blackThreshold = 0; // x <= blackThreshold means x is PossiblyOldOrBlack.

Modified: branches/safari-603-branch/Source/_javascript_Core/heap/Heap.cpp (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/heap/Heap.cpp	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/heap/Heap.cpp	2017-01-12 16:46:18 UTC (rev 210662)
@@ -263,7 +263,6 @@
     , m_codeBlocks(std::make_unique<CodeBlockSet>())
     , m_jitStubRoutines(std::make_unique<JITStubRoutineSet>())
     , m_isSafeToCollect(false)
-    , m_writeBarrierBuffer(256)
     , m_vm(vm)
     // We seed with 10ms so that GCActivityCallback::didAllocate doesn't continuously 
     // schedule the timer if we've never done a collection.
@@ -584,7 +583,7 @@
     
     for (unsigned iteration = 1; ; ++iteration) {
         if (Options::logGC())
-            dataLog("i#", iteration, " ", slotVisitor.collectorMarkStack().size(), "+", m_mutatorMarkStack->size() + slotVisitor.mutatorMarkStack().size(), " b=", m_barriersExecuted, " ");
+            dataLog("i#", iteration, " b=", m_barriersExecuted, " ");
         
         if (slotVisitor.didReachTermination()) {
             assertSharedMarkStacksEmpty();
@@ -610,6 +609,9 @@
             m_scheduler->didExecuteConstraints();
         }
         
+        if (Options::logGC())
+            dataLog(slotVisitor.collectorMarkStack().size(), "+", m_mutatorMarkStack->size() + slotVisitor.mutatorMarkStack().size(), " ");
+        
         {
             ParallelModeEnabler enabler(slotVisitor);
             slotVisitor.drainInParallel(m_scheduler->timeToResume());
@@ -940,24 +942,58 @@
     m_jitStubRoutines->deleteUnmarkedJettisonedStubRoutines();
 }
 
-void Heap::addToRememberedSet(const JSCell* cell)
+void Heap::addToRememberedSet(const JSCell* constCell)
 {
+    JSCell* cell = const_cast<JSCell*>(constCell);
     ASSERT(cell);
     ASSERT(!Options::useConcurrentJIT() || !isCompilationThread());
     m_barriersExecuted++;
-    if (!Heap::isMarkedConcurrently(cell)) {
-        // During a full collection a store into an unmarked object that had surivived past
-        // collections will manifest as a store to an unmarked black object. If the object gets
-        // marked at some time after this then it will go down the normal marking path. We can
-        // safely ignore these stores.
-        return;
-    }
+    if (m_mutatorShouldBeFenced) {
+        WTF::loadLoadFence();
+        if (!isMarkedConcurrently(cell)) {
+            // During a full collection a store into an unmarked object that had surivived past
+            // collections will manifest as a store to an unmarked PossiblyBlack object. If the
+            // object gets marked at some time after this then it will go down the normal marking
+            // path. So, we don't have to remember this object. We could return here. But we go
+            // further and attempt to re-white the object.
+            
+            RELEASE_ASSERT(m_collectionScope == CollectionScope::Full);
+            
+            if (cell->atomicCompareExchangeCellStateStrong(CellState::PossiblyBlack, CellState::DefinitelyWhite) == CellState::PossiblyBlack) {
+                // Now we protect against this race:
+                //
+                //     1) Object starts out black + unmarked.
+                //     --> We do isMarkedConcurrently here.
+                //     2) Object is marked and greyed.
+                //     3) Object is scanned and blacked.
+                //     --> We do atomicCompareExchangeCellStateStrong here.
+                //
+                // In this case we would have made the object white again, even though it should
+                // be black. This check lets us correct our mistake. This relies on the fact that
+                // isMarkedConcurrently converges monotonically to true.
+                if (isMarkedConcurrently(cell)) {
+                    // It's difficult to work out whether the object should be grey or black at
+                    // this point. We say black conservatively.
+                    cell->setCellState(CellState::PossiblyBlack);
+                }
+                
+                // Either way, we can return. Most likely, the object was not marked, and so the
+                // object is now labeled white. This means that future barrier executions will not
+                // fire. In the unlikely event that the object had become marked, we can still
+                // return anyway, since we proved that the object was not marked at the time that
+                // we executed this slow path.
+            }
+            
+            return;
+        }
+    } else
+        ASSERT(Heap::isMarkedConcurrently(cell));
     // It could be that the object was *just* marked. This means that the collector may set the
     // state to DefinitelyGrey and then to PossiblyOldOrBlack at any time. It's OK for us to
     // race with the collector here. If we win then this is accurate because the object _will_
     // get scanned again. If we lose then someone else will barrier the object again. That would
     // be unfortunate but not the end of the world.
-    cell->setCellState(CellState::DefinitelyGrey);
+    cell->setCellState(CellState::PossiblyGrey);
     m_mutatorMarkStack->append(cell);
 }
 
@@ -1177,7 +1213,6 @@
     
     vm()->shadowChicken().update(*vm(), vm()->topCallFrame);
     
-    flushWriteBarrierBuffer();
     m_structureIDTable.flushOldTables();
     m_objectSpace.stopAllocating();
     
@@ -1597,11 +1632,6 @@
         observer->willGarbageCollect();
 }
 
-void Heap::flushWriteBarrierBuffer()
-{
-    m_writeBarrierBuffer.flush(*this);
-}
-
 void Heap::prepareForMarking()
 {
     m_objectSpace.prepareForMarking();
@@ -1882,12 +1912,6 @@
     m_objectSpace.forEachDeadCell(iterationScope, Zombify());
 }
 
-void Heap::flushWriteBarrierBuffer(JSCell* cell)
-{
-    m_writeBarrierBuffer.flush(*this);
-    m_writeBarrierBuffer.add(cell);
-}
-
 bool Heap::shouldDoFullCollection(std::optional<CollectionScope> scope) const
 {
     if (!Options::useGenerationalGC())
@@ -1965,7 +1989,7 @@
         // In this case, the barrierThreshold is the tautological threshold, so from could still be
         // not black. But we can't know for sure until we fire off a fence.
         WTF::storeLoadFence();
-        if (from->cellState() != CellState::PossiblyOldOrBlack)
+        if (from->cellState() != CellState::PossiblyBlack)
             return;
     }
     
@@ -2213,7 +2237,7 @@
                 [&] (CodeBlock* codeBlock) {
                     // Visit the CodeBlock as a constraint only if it's black.
                     if (Heap::isMarked(codeBlock)
-                        && codeBlock->cellState() == CellState::PossiblyOldOrBlack)
+                        && codeBlock->cellState() == CellState::PossiblyBlack)
                         slotVisitor.visitAsConstraint(codeBlock);
                 });
         },

Modified: branches/safari-603-branch/Source/_javascript_Core/heap/Heap.h (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/heap/Heap.h	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/heap/Heap.h	2017-01-12 16:46:18 UTC (rev 210662)
@@ -43,7 +43,6 @@
 #include "VisitRaceKey.h"
 #include "WeakHandleOwner.h"
 #include "WeakReferenceHarvester.h"
-#include "WriteBarrierBuffer.h"
 #include "WriteBarrierSupport.h"
 #include <wtf/AutomaticThread.h>
 #include <wtf/Deque.h>
@@ -125,9 +124,6 @@
     // Take this if you know that from->cellState() < barrierThreshold.
     JS_EXPORT_PRIVATE void writeBarrierSlowPath(const JSCell* from);
 
-    WriteBarrierBuffer& writeBarrierBuffer() { return m_writeBarrierBuffer; }
-    void flushWriteBarrierBuffer(JSCell*);
-    
     void writeBarrierOpaqueRoot(void*);
 
     Heap(VM*, HeapType);
@@ -445,7 +441,6 @@
     
     void suspendCompilerThreads();
     void willStartCollection(std::optional<CollectionScope>);
-    void flushWriteBarrierBuffer();
     void prepareForMarking();
     
     void markToFixpoint(double gcStartTime);
@@ -564,7 +559,6 @@
     
     bool m_isSafeToCollect;
 
-    WriteBarrierBuffer m_writeBarrierBuffer;
     bool m_mutatorShouldBeFenced { Options::forceFencedBarrier() };
     unsigned m_barrierThreshold { Options::forceFencedBarrier() ? tautologicalThreshold : blackThreshold };
     Vector<bool*> m_mutatorShouldBeFencedCaches;

Modified: branches/safari-603-branch/Source/_javascript_Core/heap/SlotVisitor.cpp (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/heap/SlotVisitor.cpp	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/heap/SlotVisitor.cpp	2017-01-12 16:46:18 UTC (rev 210662)
@@ -204,7 +204,7 @@
         JSCell* jsCell = static_cast<JSCell*>(heapCell);
         validateCell(jsCell);
         
-        jsCell->setCellState(CellState::DefinitelyGrey);
+        jsCell->setCellState(CellState::PossiblyGrey);
 
         appendToMarkStack(jsCell);
         return;
@@ -266,7 +266,7 @@
     // Indicate that the object is grey and that:
     // In case of concurrent GC: it's the first time it is grey in this GC cycle.
     // In case of eden collection: it's a new object that became grey rather than an old remembered object.
-    cell->setCellState(CellState::DefinitelyGrey);
+    cell->setCellState(CellState::PossiblyGrey);
     
     appendToMarkStack(container, cell);
 }
@@ -284,7 +284,7 @@
 {
     ASSERT(Heap::isMarkedConcurrently(cell));
     ASSERT(!cell->isZapped());
-    ASSERT(cell->cellState() == CellState::DefinitelyGrey);
+    ASSERT(cell->cellState() == CellState::PossiblyGrey);
     
     container.noteMarked();
     
@@ -371,7 +371,7 @@
     // not clear to me that it would be correct or profitable to bail here if the object is already
     // black.
     
-    cell->setCellState(CellState::PossiblyOldOrBlack);
+    cell->setCellState(CellState::PossiblyBlack);
     
     WTF::storeLoadFence();
     

Deleted: branches/safari-603-branch/Source/_javascript_Core/heap/WriteBarrierBuffer.cpp (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/heap/WriteBarrierBuffer.cpp	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/heap/WriteBarrierBuffer.cpp	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,69 +0,0 @@
-/*
- * Copyright (C) 2013 Apple Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
- * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
- * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
- * THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include "config.h"
-#include "WriteBarrierBuffer.h"
-
-#include "GCAssertions.h"
-#include "Heap.h"
-#include "JSCell.h"
-#include "JSCInlines.h"
-#include "Structure.h"
-
-namespace JSC {
-
-WriteBarrierBuffer::WriteBarrierBuffer(unsigned capacity)
-    : m_currentIndex(0)
-    , m_capacity(capacity)
-    , m_buffer(static_cast<JSCell**>(fastMalloc(sizeof(JSCell*) * capacity)))
-{
-}
-
-WriteBarrierBuffer::~WriteBarrierBuffer()
-{
-    fastFree(m_buffer);
-}
-
-void WriteBarrierBuffer::flush(Heap& heap)
-{
-    ASSERT(m_currentIndex <= m_capacity);
-    for (size_t i = 0; i < m_currentIndex; ++i)
-        heap.writeBarrier(m_buffer[i]);
-    m_currentIndex = 0;
-}
-
-void WriteBarrierBuffer::reset()
-{
-    m_currentIndex = 0;
-}
-
-void WriteBarrierBuffer::add(JSCell* cell)
-{
-    ASSERT_GC_OBJECT_LOOKS_VALID(cell);
-    ASSERT(m_currentIndex < m_capacity);
-    m_buffer[m_currentIndex++] = cell;
-}
-
-} // namespace JSC

Deleted: branches/safari-603-branch/Source/_javascript_Core/heap/WriteBarrierBuffer.h (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/heap/WriteBarrierBuffer.h	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/heap/WriteBarrierBuffer.h	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,65 +0,0 @@
-/*
- * Copyright (C) 2013, 2015 Apple Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
- * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
- * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
- * THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#pragma once
-
-#include <wtf/FastMalloc.h>
-
-namespace JSC {
-
-class Heap;
-class JSCell;
-
-class WriteBarrierBuffer {
-public:
-    WriteBarrierBuffer(unsigned capacity);
-    ~WriteBarrierBuffer();
-
-    void add(JSCell*);
-    void flush(Heap&);
-    void reset();
-
-    unsigned* currentIndexAddress()
-    {
-        return &m_currentIndex;
-    }
-
-    unsigned capacity() const
-    {
-        return m_capacity;
-    }
-
-    JSCell** buffer()
-    {
-        return m_buffer;
-    }
-
-private:
-    unsigned m_currentIndex;
-    const unsigned m_capacity;
-    JSCell** const m_buffer;
-};
-
-} // namespace JSC

Modified: branches/safari-603-branch/Source/_javascript_Core/jit/JITOperations.cpp (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/jit/JITOperations.cpp	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/jit/JITOperations.cpp	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2013-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -2188,13 +2188,6 @@
     return reinterpret_cast<char*>(result);
 }
 
-void JIT_OPERATION operationFlushWriteBarrierBuffer(ExecState* exec, JSCell* cell)
-{
-    VM* vm = &exec->vm();
-    NativeCallFrameTracer tracer(vm, exec);
-    vm->heap.flushWriteBarrierBuffer(cell);
-}
-
 void JIT_OPERATION operationOSRWriteBarrier(ExecState* exec, JSCell* cell)
 {
     VM* vm = &exec->vm();

Modified: branches/safari-603-branch/Source/_javascript_Core/jit/JITOperations.h (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/jit/JITOperations.h	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/jit/JITOperations.h	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2013-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -426,7 +426,6 @@
 char* JIT_OPERATION operationReallocateButterflyToHavePropertyStorageWithInitialCapacity(ExecState*, JSObject*) WTF_INTERNAL;
 char* JIT_OPERATION operationReallocateButterflyToGrowPropertyStorage(ExecState*, JSObject*, size_t newSize) WTF_INTERNAL;
 
-void JIT_OPERATION operationFlushWriteBarrierBuffer(ExecState*, JSCell*);
 void JIT_OPERATION operationWriteBarrierSlowPath(ExecState*, JSCell*);
 void JIT_OPERATION operationOSRWriteBarrier(ExecState*, JSCell*);
 

Modified: branches/safari-603-branch/Source/_javascript_Core/runtime/JSCellInlines.h (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/runtime/JSCellInlines.h	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/runtime/JSCellInlines.h	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2012-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -41,7 +41,7 @@
 namespace JSC {
 
 inline JSCell::JSCell(CreatingEarlyCellTag)
-    : m_cellState(CellState::DefinitelyNewAndWhite)
+    : m_cellState(CellState::DefinitelyWhite)
 {
     ASSERT(!isCompilationThread());
 }
@@ -51,7 +51,7 @@
     , m_indexingTypeAndMisc(structure->indexingTypeIncludingHistory())
     , m_type(structure->typeInfo().type())
     , m_flags(structure->typeInfo().inlineTypeFlags())
-    , m_cellState(CellState::DefinitelyNewAndWhite)
+    , m_cellState(CellState::DefinitelyWhite)
 {
     ASSERT(!isCompilationThread());
 }

Modified: branches/safari-603-branch/Source/_javascript_Core/runtime/StructureIDBlob.h (210661 => 210662)


--- branches/safari-603-branch/Source/_javascript_Core/runtime/StructureIDBlob.h	2017-01-12 16:46:13 UTC (rev 210661)
+++ branches/safari-603-branch/Source/_javascript_Core/runtime/StructureIDBlob.h	2017-01-12 16:46:18 UTC (rev 210662)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2014-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -46,7 +46,7 @@
         u.fields.indexingTypeIncludingHistory = indexingTypeIncludingHistory;
         u.fields.type = typeInfo.type();
         u.fields.inlineTypeFlags = typeInfo.inlineTypeFlags();
-        u.fields.defaultCellState = CellState::DefinitelyNewAndWhite;
+        u.fields.defaultCellState = CellState::DefinitelyWhite;
     }
 
     void operator=(const StructureIDBlob& other) { u.doubleWord = other.u.doubleWord; }
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