Title: [169816] trunk/Source/_javascript_Core
- Revision
- 169816
- Author
- rn...@webkit.org
- Date
- 2014-06-11 12:29:51 -0700 (Wed, 11 Jun 2014)
Log Message
Structure::get should instantiate DeferGC only when materializing property map
https://bugs.webkit.org/show_bug.cgi?id=133727
Reviewed by Geoffrey Garen.
DeferGC instances in Structure::get was added in http://trac.webkit.org/r157539 in order to avoid
collecting the property table newly created by materializePropertyMapIfNecessary since GC can happen
when GCSafeConcurrentJITLocker goes out of scope.
However, always instantiating DeferGC inside Structure::get introduced a new performance bottleneck
in JSObject::getPropertySlot because frequently incrementing and decrementing a counter in vm.m_heap
and running a release assertion inside Heap::incrementDeferralDepth() is expensive.
Work around this by instantiating DeferGC only when we're actually calling materializePropertyMap,
and immediately storing a pointer to the newly created property table in the stack before DeferGC
goes out of scope so that the property table will be marked.
This shows 13-16% improvement on the microbenchmark attached in the bug.
* runtime/JSCJSValue.cpp:
* runtime/JSObject.h:
(JSC::JSObject::fastGetOwnPropertySlot):
* runtime/Structure.h:
(JSC::Structure::materializePropertyMapIfNecessary):
* runtime/StructureInlines.h:
(JSC::Structure::get):
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (169815 => 169816)
--- trunk/Source/_javascript_Core/ChangeLog 2014-06-11 18:40:13 UTC (rev 169815)
+++ trunk/Source/_javascript_Core/ChangeLog 2014-06-11 19:29:51 UTC (rev 169816)
@@ -1,3 +1,32 @@
+2014-06-11 Ryosuke Niwa <rn...@webkit.org>
+
+ Structure::get should instantiate DeferGC only when materializing property map
+ https://bugs.webkit.org/show_bug.cgi?id=133727
+
+ Reviewed by Geoffrey Garen.
+
+ DeferGC instances in Structure::get was added in http://trac.webkit.org/r157539 in order to avoid
+ collecting the property table newly created by materializePropertyMapIfNecessary since GC can happen
+ when GCSafeConcurrentJITLocker goes out of scope.
+
+ However, always instantiating DeferGC inside Structure::get introduced a new performance bottleneck
+ in JSObject::getPropertySlot because frequently incrementing and decrementing a counter in vm.m_heap
+ and running a release assertion inside Heap::incrementDeferralDepth() is expensive.
+
+ Work around this by instantiating DeferGC only when we're actually calling materializePropertyMap,
+ and immediately storing a pointer to the newly created property table in the stack before DeferGC
+ goes out of scope so that the property table will be marked.
+
+ This shows 13-16% improvement on the microbenchmark attached in the bug.
+
+ * runtime/JSCJSValue.cpp:
+ * runtime/JSObject.h:
+ (JSC::JSObject::fastGetOwnPropertySlot):
+ * runtime/Structure.h:
+ (JSC::Structure::materializePropertyMapIfNecessary):
+ * runtime/StructureInlines.h:
+ (JSC::Structure::get):
+
2014-06-11 Andreas Kling <akl...@apple.com>
Some JSValue::get() micro-optimzations.
Modified: trunk/Source/_javascript_Core/runtime/JSCJSValue.cpp (169815 => 169816)
--- trunk/Source/_javascript_Core/runtime/JSCJSValue.cpp 2014-06-11 18:40:13 UTC (rev 169815)
+++ trunk/Source/_javascript_Core/runtime/JSCJSValue.cpp 2014-06-11 19:29:51 UTC (rev 169816)
@@ -34,6 +34,7 @@
#include "JSGlobalObject.h"
#include "JSNotAnObject.h"
#include "NumberObject.h"
+#include "StructureInlines.h"
#include <wtf/MathExtras.h>
#include <wtf/StringExtras.h>
Modified: trunk/Source/_javascript_Core/runtime/JSObject.h (169815 => 169816)
--- trunk/Source/_javascript_Core/runtime/JSObject.h 2014-06-11 18:40:13 UTC (rev 169815)
+++ trunk/Source/_javascript_Core/runtime/JSObject.h 2014-06-11 19:29:51 UTC (rev 169816)
@@ -1256,7 +1256,7 @@
ALWAYS_INLINE bool JSObject::fastGetOwnPropertySlot(ExecState* exec, VM& vm, Structure& structure, PropertyName propertyName, PropertySlot& slot)
{
- if (!TypeInfo::overridesGetOwnPropertySlot(inlineTypeFlags()))
+ if (LIKELY(!TypeInfo::overridesGetOwnPropertySlot(inlineTypeFlags())))
return asObject(this)->inlineGetOwnPropertySlot(vm, structure, propertyName, slot);
return structure.classInfo()->methodTable.getOwnPropertySlot(this, exec, propertyName, slot);
}
Modified: trunk/Source/_javascript_Core/runtime/Structure.h (169815 => 169816)
--- trunk/Source/_javascript_Core/runtime/Structure.h 2014-06-11 18:40:13 UTC (rev 169815)
+++ trunk/Source/_javascript_Core/runtime/Structure.h 2014-06-11 19:29:51 UTC (rev 169816)
@@ -434,6 +434,18 @@
if (!propertyTable() && previousID())
materializePropertyMap(vm);
}
+ void materializePropertyMapIfNecessary(VM& vm, PropertyTable*& table)
+ {
+ ASSERT(!isCompilationThread());
+ ASSERT(structure()->classInfo() == info());
+ ASSERT(checkOffsetConsistency());
+ table = propertyTable().get();
+ if (!table && previousID()) {
+ DeferGC deferGC(vm.heap);
+ materializePropertyMap(vm);
+ table = propertyTable().get();
+ }
+ }
void materializePropertyMapIfNecessaryForPinning(VM& vm, DeferGC&)
{
ASSERT(structure()->classInfo() == info());
Modified: trunk/Source/_javascript_Core/runtime/StructureInlines.h (169815 => 169816)
--- trunk/Source/_javascript_Core/runtime/StructureInlines.h 2014-06-11 18:40:13 UTC (rev 169815)
+++ trunk/Source/_javascript_Core/runtime/StructureInlines.h 2014-06-11 19:29:51 UTC (rev 169816)
@@ -77,12 +77,12 @@
{
ASSERT(!isCompilationThread());
ASSERT(structure()->classInfo() == info());
- DeferGC deferGC(vm.heap);
- materializePropertyMapIfNecessary(vm, deferGC);
- if (!propertyTable())
+ PropertyTable* propertyTable;
+ materializePropertyMapIfNecessary(vm, propertyTable);
+ if (!propertyTable)
return invalidOffset;
- PropertyMapEntry* entry = propertyTable()->get(propertyName.uid());
+ PropertyMapEntry* entry = propertyTable->get(propertyName.uid());
return entry ? entry->offset : invalidOffset;
}
@@ -90,12 +90,12 @@
{
ASSERT(!isCompilationThread());
ASSERT(structure()->classInfo() == info());
- DeferGC deferGC(vm.heap);
- materializePropertyMapIfNecessary(vm, deferGC);
- if (!propertyTable())
+ PropertyTable* propertyTable;
+ materializePropertyMapIfNecessary(vm, propertyTable);
+ if (!propertyTable)
return invalidOffset;
- PropertyMapEntry* entry = propertyTable()->findWithString(name.impl()).first;
+ PropertyMapEntry* entry = propertyTable->findWithString(name.impl()).first;
return entry ? entry->offset : invalidOffset;
}
@@ -104,12 +104,12 @@
ASSERT(!isCompilationThread());
ASSERT(structure()->classInfo() == info());
- DeferGC deferGC(vm.heap);
- materializePropertyMapIfNecessary(vm, deferGC);
- if (!propertyTable())
+ PropertyTable* propertyTable;
+ materializePropertyMapIfNecessary(vm, propertyTable);
+ if (!propertyTable)
return invalidOffset;
- PropertyMapEntry* entry = propertyTable()->get(propertyName.uid());
+ PropertyMapEntry* entry = propertyTable->get(propertyName.uid());
if (!entry)
return invalidOffset;
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