Changeset 288537 in webkit for trunk/Source/JavaScriptCore

Timestamp:

Jan 24, 2022, 9:13:18 PM (3 years ago)

Author:

Cameron McCormack

Message:

Remove VM::stringCache
​https://bugs.webkit.org/show_bug.cgi?id=235536

Reviewed by Sam Weinig.

We consult VM::stringCache when creating a JSString, but since
bug 142115 we never insert anything into it.

Removing this results in almost-significant improvements in the VueJS,
Vanilla-ES2015, and jQuery sub-tests of Speedometer 2 (of 0.5-2%,
0.03 <= p <= 0.05), and an almost significant 0.2% improvement in the
overall score (p = 0.06).

• runtime/JSString.cpp:

(JSC::jsStringWithCacheSlowCase):

• runtime/VM.cpp:

(JSC::VM::VM):

• runtime/VM.h:

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• runtime/JSString.cpp (modified) (1 diff)
• runtime/VM.cpp (modified) (1 diff)
• runtime/VM.h (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2022-01-24  Cameron McCormack  <[email protected]>
+
+        Remove VM::stringCache
+        https://bugs.webkit.org/show_bug.cgi?id=235536
+
+        Reviewed by Sam Weinig.
+
+        We consult VM::stringCache when creating a JSString, but since
+        bug 142115 we never insert anything into it.
+
+        Removing this results in almost-significant improvements in the VueJS,
+        Vanilla-ES2015, and jQuery sub-tests of Speedometer 2 (of 0.5-2%,
+        0.03 <= p <= 0.05), and an almost significant 0.2% improvement in the
+        overall score (p = 0.06).
+
+        * runtime/JSString.cpp:
+        (JSC::jsStringWithCacheSlowCase):
+        * runtime/VM.cpp:
+        (JSC::VM::VM):
+        * runtime/VM.h:
+
 2022-01-24  Diego Pino Garcia  <[email protected]>
 

trunk/Source/JavaScriptCore/runtime/JSString.cpp

@@ -437 +437 @@
 JSString* jsStringWithCacheSlowCase(VM& vm, StringImpl& stringImpl)
 {
-    if (JSString* string = vm.stringCache.get(&stringImpl))
-        return string;
-
     JSString* string = jsString(vm, String(stringImpl));
     vm.lastCachedString.set(vm, string);

trunk/Source/JavaScriptCore/runtime/VM.cpp

@@ -219 +219 @@
     , emptyList(new ArgList)
     , machineCodeBytesPerBytecodeWordForBaselineJIT(makeUnique<SimpleStats>())
-    , stringCache(*this)
     , symbolImplToSymbolMap(*this)
     , structureCache(*this)

trunk/Source/JavaScriptCore/runtime/VM.h

@@ -586 +586 @@
     NumericStrings numericStrings;
     std::unique_ptr<SimpleStats> machineCodeBytesPerBytecodeWordForBaselineJIT;
-    WeakGCMap<StringImpl*, JSString, PtrHash<StringImpl*>> stringCache;
     Strong<JSString> lastCachedString;
     JSONAtomStringCache jsonAtomStringCache;