Changeset 123690 in webkit for trunk/Source/JavaScriptCore/runtime/JSObject.cpp

Timestamp:

Jul 25, 2012, 6:22:59 PM (13 years ago)

Author:

[email protected]

Message:

JSC GC object copying APIs should allow for greater flexibility
​https://bugs.webkit.org/show_bug.cgi?id=92316

Reviewed by Mark Hahnenberg.

It's now the case that visitChildren() methods can directly pin and allocate in new space during copying.
They can also do the copying and marking themselves. This new API is only used for JSObjects for now.

• JavaScriptCore.xcodeproj/project.pbxproj:
• heap/MarkStack.cpp:

(JSC::SlotVisitor::allocateNewSpaceSlow):
(JSC::SlotVisitor::allocateNewSpaceOrPin):
(JSC):
(JSC::SlotVisitor::copyAndAppend):

• heap/MarkStack.h:

(MarkStack):
(JSC::MarkStack::appendUnbarrieredValue):
(JSC):

• heap/SlotVisitor.h:
• heap/SlotVisitorInlineMethods.h: Added.

(JSC):
(JSC::SlotVisitor::checkIfShouldCopyAndPinOtherwise):
(JSC::SlotVisitor::allocateNewSpace):

• runtime/JSObject.cpp:

(JSC::JSObject::visitOutOfLineStorage):
(JSC):
(JSC::JSObject::visitChildren):
(JSC::JSFinalObject::visitChildren):

• runtime/JSObject.h:

(JSObject):

File:

• trunk/Source/JavaScriptCore/runtime/JSObject.cpp (modified) (4 diffs)

trunk/Source/JavaScriptCore/runtime/JSObject.cpp

@@ -39 +39 @@
 #include "PropertyDescriptor.h"
 #include "PropertyNameArray.h"
+#include "SlotVisitorInlineMethods.h"
 #include <math.h>
 #include <wtf/Assertions.h>
@@ -84 +85 @@
         }
     }
+}
+
+ALWAYS_INLINE void JSObject::visitOutOfLineStorage(SlotVisitor& visitor, PropertyStorage storage, size_t storageSize)
+{
+    ASSERT(storage);
+    ASSERT(storageSize);
+    
+    size_t capacity = structure()->outOfLineCapacity();
+    ASSERT(capacity);
+    size_t capacityInBytes = capacity * sizeof(WriteBarrierBase<Unknown>);
+    PropertyStorage baseOfStorage = storage - capacity - 1;
+    if (visitor.checkIfShouldCopyAndPinOtherwise(baseOfStorage, capacityInBytes)) {
+        PropertyStorage newBaseOfStorage = static_cast<PropertyStorage>(visitor.allocateNewSpace(capacityInBytes));
+        PropertyStorage currentTarget = newBaseOfStorage + capacity;
+        PropertyStorage newStorage = currentTarget + 1;
+        PropertyStorage currentSource = storage - 1;
+        for (size_t count = storageSize; count--;) {
+            JSValue value = (--currentSource)->get();
+            ASSERT(value);
+            visitor.appendUnbarrieredValue(&value);
+            (--currentTarget)->setWithoutWriteBarrier(value);
+        }
+        m_outOfLineStorage.set(newStorage, StorageBarrier::Unchecked);
+    } else
+        visitor.appendValues(storage - storageSize - 1, storageSize);
 }
 
@@ -98 +124 @@
 
     PropertyStorage storage = thisObject->outOfLineStorage();
-    if (storage) {
-        size_t storageSize = thisObject->structure()->outOfLineSizeForKnownNonFinalObject();
-        size_t capacity = thisObject->structure()->outOfLineCapacity();
-        // We have this extra temp here to slake GCC's thirst for the blood of those who dereference type-punned pointers.
-        void* temp = storage - capacity - 1;
-        visitor.copyAndAppend(&temp, capacity * sizeof(WriteBarrierBase<Unknown>), (storage - storageSize - 1)->slot(), storageSize);
-        storage = static_cast<PropertyStorage>(temp) + capacity + 1;
-        thisObject->m_outOfLineStorage.set(storage, StorageBarrier::Unchecked);
-    }
+    if (storage)
+        thisObject->visitOutOfLineStorage(visitor, storage, thisObject->structure()->outOfLineSizeForKnownNonFinalObject());
 
 #if !ASSERT_DISABLED
@@ -125 +144 @@
 
     PropertyStorage storage = thisObject->outOfLineStorage();
-    if (storage) {
-        size_t storageSize = thisObject->structure()->outOfLineSizeForKnownFinalObject();
-        size_t capacity = thisObject->structure()->outOfLineCapacity();
-        // We have this extra temp here to slake GCC's thirst for the blood of those who dereference type-punned pointers.
-        void* temp = storage - capacity - 1;
-        visitor.copyAndAppend(&temp, thisObject->structure()->outOfLineCapacity() * sizeof(WriteBarrierBase<Unknown>), (storage - storageSize - 1)->slot(), storageSize);
-        storage = static_cast<PropertyStorage>(temp) + capacity + 1;
-        thisObject->m_outOfLineStorage.set(storage, StorageBarrier::Unchecked);
-    }
+    if (storage)
+        thisObject->visitOutOfLineStorage(visitor, storage, thisObject->structure()->outOfLineSizeForKnownFinalObject());
 
     size_t storageSize = thisObject->structure()->inlineSizeForKnownFinalObject();