Move the JSString cache from DOMWrapperWorld to VM.

<https://webkit.org/b/131940>

Source/JavaScriptCore:
Reviewed by Geoff Garen.

* runtime/VM.h:

Source/WebCore:
Since there's no need for JSStrings to be world-specific, this patch
moves the string cache to JSC::VM. This makes jsStringWithCache()
a lot faster since it no longer has to jump through twenty-eleven
hoops to find the DOMWrapperWorld.

Reviewed by Geoff Garen.

* bindings/js/DOMWrapperWorld.cpp:
(WebCore::DOMWrapperWorld::clearWrappers):
* bindings/js/DOMWrapperWorld.h:
* bindings/js/JSDOMBinding.cpp:
(WebCore::jsStringWithCache):

Canonical link: https://commits.webkit.org/150025@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@167605 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/JavaScriptCore/ChangeLog

@@ -1,3 +1,12 @@
+2014-04-21  Andreas Kling  <akling@apple.com>
+
+        Move the JSString cache from DOMWrapperWorld to VM.
+        <https://webkit.org/b/131940>
+
+        Reviewed by Geoff Garen.
+
+        * runtime/VM.h:
+
 2014-04-19  Filip Pizlo  <fpizlo@apple.com>
 
         Take block execution count estimates into account when voting double

Source/JavaScriptCore/runtime/VM.h

@@ -295,6 +295,7 @@ namespace JSC {
         NumericStrings numericStrings;
         DateInstanceCache dateInstanceCache;
         WTF::SimpleStats machineCodeBytesPerBytecodeWordForBaselineJIT;
+        WeakGCMap<StringImpl*, JSString, PtrHash<StringImpl*>> stringCache;
 
         AtomicStringTable* atomicStringTable() const { return m_atomicStringTable; }
 

Source/WebCore/ChangeLog

@@ -1,3 +1,21 @@
+2014-04-21  Andreas Kling  <akling@apple.com>
+
+        Move the JSString cache from DOMWrapperWorld to VM.
+        <https://webkit.org/b/131940>
+
+        Since there's no need for JSStrings to be world-specific, this patch
+        moves the string cache to JSC::VM. This makes jsStringWithCache()
+        a lot faster since it no longer has to jump through twenty-eleven
+        hoops to find the DOMWrapperWorld.
+
+        Reviewed by Geoff Garen.
+
+        * bindings/js/DOMWrapperWorld.cpp:
+        (WebCore::DOMWrapperWorld::clearWrappers):
+        * bindings/js/DOMWrapperWorld.h:
+        * bindings/js/JSDOMBinding.cpp:
+        (WebCore::jsStringWithCache):
+
 2014-04-21  David Hyatt  <hyatt@apple.com>
 
         [New Multicolumn] Column balancing is slow on float-multicol.html

Source/WebCore/bindings/js/DOMWrapperWorld.cpp

@@ -53,7 +53,6 @@ DOMWrapperWorld::~DOMWrapperWorld()
 void DOMWrapperWorld::clearWrappers()
 {
     m_wrappers.clear();
-    m_stringCache.clear();
 
     // These items are created lazily.
     while (!m_scriptControllersWithWindowShells.isEmpty())

Source/WebCore/bindings/js/DOMWrapperWorld.h

@@ -23,7 +23,6 @@
 #define DOMWrapperWorld_h
 
 #include "JSDOMGlobalObject.h"
-#include <runtime/WeakGCMap.h>
 #include <wtf/Forward.h>
 
 namespace WebCore {
@@ -33,7 +32,6 @@ class JSDOMWrapper;
 class ScriptController;
 
 typedef HashMap<void*, JSC::Weak<JSC::JSObject>> DOMObjectWrapperMap;
-typedef JSC::WeakGCMap<StringImpl*, JSC::JSString, PtrHash<StringImpl*>> JSStringCache;
 
 class DOMWrapperWorld : public RefCounted<DOMWrapperWorld> {
 public:
@@ -51,7 +49,6 @@ class DOMWrapperWorld : public RefCounted<DOMWrapperWorld> {
 
     // FIXME: can we make this private?
     DOMObjectWrapperMap m_wrappers;
-    JSStringCache m_stringCache;
     HashMap<CSSValue*, void*> m_cssValueRoots;
 
     bool isNormal() const { return m_isNormal; }

Source/WebCore/bindings/js/JSDOMBinding.cpp

@@ -65,22 +65,20 @@ const JSC::HashTable& getHashTableForGlobalData(VM& vm, const JSC::HashTable& st
 
 JSC::JSValue jsStringWithCache(JSC::ExecState* exec, const String& s)
 {
+    JSC::VM& vm = exec->vm();
     StringImpl* stringImpl = s.impl();
     if (!stringImpl || !stringImpl->length())
-        return jsEmptyString(exec);
+        return jsEmptyString(&vm);
 
     if (stringImpl->length() == 1) {
         UChar singleCharacter = (*stringImpl)[0u];
-        if (singleCharacter <= JSC::maxSingleCharacterString) {
-            JSC::VM* vm = &exec->vm();
-            return vm->smallStrings.singleCharacterString(static_cast<unsigned char>(singleCharacter));
-        }
+        if (singleCharacter <= JSC::maxSingleCharacterString)
+            return vm.smallStrings.singleCharacterString(static_cast<unsigned char>(singleCharacter));
     }
 
-    JSStringCache& stringCache = currentWorld(exec).m_stringCache;
-    JSStringCache::AddResult addResult = stringCache.add(stringImpl, nullptr);
+    auto addResult = vm.stringCache.add(stringImpl, nullptr);
     if (addResult.isNewEntry)
-        addResult.iterator->value = JSC::jsString(exec, String(stringImpl));
+        addResult.iterator->value = JSC::jsString(&vm, String(stringImpl));
     return JSC::JSValue(addResult.iterator->value.get());
 }