Changeset 37323 in webkit

Timestamp:

Oct 5, 2008 7:48:08 PM (16 years ago)

Author:

mjs@apple.com

Message:

2008-10-05 Maciej Stachowiak <​mjs@apple.com>

Reviewed by Oliver Hunt.

• fixed "REGRESSION (r37297): fast/js/deep-recursion-test takes too long and times out" ​https://bugs.webkit.org/show_bug.cgi?id=21375

The problem is that dynamicGlobalObject had become O(N) in number
of call frames, but unwinding the stack for an exception called it
for every call frame, resulting in O(N^{2) behavior for an
exception thrown from inside deep recursion.}

Instead of doing it that way, stash the dynamic global object in JSGlobalData.

• JavaScriptCore.exp:
• VM/Machine.cpp: (JSC::DynamicGlobalObjectScope::DynamicGlobalObjectScope): Helper class to temporarily store and later restore a dynamicGlobalObject in JSGlobalData. (JSC::DynamicGlobalObjectScope::~DynamicGlobalObjectScope): (JSC::Machine::execute): In each version, establish a DynamicGlobalObjectScope. For ProgramNode, always establish set new dynamicGlobalObject, for FunctionBody and Eval, only if none is currently set.
• VM/Machine.h:
• kjs/ExecState.h:
• kjs/JSGlobalData.cpp: (JSC::JSGlobalData::JSGlobalData): Ininitalize new dynamicGlobalObject field to 0.
• kjs/JSGlobalData.h:
• kjs/JSGlobalObject.h: (JSC::ExecState::dynamicGlobalObject): Moved here from ExecState for benefit of inlining. Return lexical global object if this is a globalExec(), otherwise look in JSGlobalData for the one stashed there.

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• JavaScriptCore.exp (modified) (1 diff)
• VM/Machine.cpp (modified) (6 diffs)
• VM/Machine.h (modified) (1 diff)
• kjs/ExecState.h (modified) (1 diff)
• kjs/JSGlobalData.cpp (modified) (1 diff)
• kjs/JSGlobalData.h (modified) (1 diff)
• kjs/JSGlobalObject.h (modified) (1 diff)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2008-10-05  Maciej Stachowiak  <mjs@apple.com>
+
+        Reviewed by Oliver Hunt.
+        
+        - fixed "REGRESSION (r37297): fast/js/deep-recursion-test takes too long and times out"
+        https://bugs.webkit.org/show_bug.cgi?id=21375
+        
+        The problem is that dynamicGlobalObject had become O(N) in number
+        of call frames, but unwinding the stack for an exception called it
+        for every call frame, resulting in O(N^2) behavior for an
+        exception thrown from inside deep recursion.
+
+        Instead of doing it that way, stash the dynamic global object in JSGlobalData.
+        
+        * JavaScriptCore.exp:
+        * VM/Machine.cpp:
+        (JSC::DynamicGlobalObjectScope::DynamicGlobalObjectScope): Helper class to temporarily
+        store and later restore a dynamicGlobalObject in JSGlobalData.
+        (JSC::DynamicGlobalObjectScope::~DynamicGlobalObjectScope):
+        (JSC::Machine::execute): In each version, establish a DynamicGlobalObjectScope.
+        For ProgramNode, always establish set new dynamicGlobalObject, for FunctionBody and Eval,
+        only if none is currently set.
+        * VM/Machine.h:
+        * kjs/ExecState.h:
+        * kjs/JSGlobalData.cpp:
+        (JSC::JSGlobalData::JSGlobalData): Ininitalize new dynamicGlobalObject field to 0.
+        * kjs/JSGlobalData.h:
+        * kjs/JSGlobalObject.h:
+        (JSC::ExecState::dynamicGlobalObject): Moved here from ExecState for benefit of inlining.
+        Return lexical global object if this is a globalExec(), otherwise look in JSGlobalData
+        for the one stashed there.
+
 2008-10-05  Sam Weinig  <sam@webkit.org>
 

trunk/JavaScriptCore/JavaScriptCore.exp

@@ -207 +207 @@
 __ZN3JSC7CStringaSERKS0_
 __ZN3JSC7JSArray4infoE
-__ZN3JSC7Machine14firstCallFrameEPKNS_8RegisterE
 __ZN3JSC7Profile10restoreAllEv
 __ZN3JSC7Profile5focusEPKNS_11ProfileNodeE

trunk/JavaScriptCore/VM/Machine.cpp

@@ -869 +869 @@
 }
 
+class DynamicGlobalObjectScope {
+public:
+    DynamicGlobalObjectScope(ExecState* exec, JSGlobalObject* dynamicGlobalObject) 
+        : m_exec(exec)
+        , m_savedGlobalObject(exec->globalData().dynamicGlobalObject)
+    {
+        exec->globalData().dynamicGlobalObject = dynamicGlobalObject;
+    }
+
+    ~DynamicGlobalObjectScope()
+    {
+        m_exec->globalData().dynamicGlobalObject = m_savedGlobalObject;
+    }
+
+private:
+    ExecState* m_exec;
+    JSGlobalObject* m_savedGlobalObject;
+};
+
 JSValue* Machine::execute(ProgramNode* programNode, ExecState* exec, ScopeChainNode* scopeChain, JSObject* thisObj, JSValue** exception)
 {
@@ -886 +905 @@
         return jsNull();
     }
+
+    DynamicGlobalObjectScope globalObjectScope(exec, scopeChain->globalObject());
 
     JSGlobalObject* lastGlobalObject = m_registerFile.globalObject();
@@ -921 +942 @@
 
     m_registerFile.shrink(oldEnd);
+
     return result;
 }
@@ -940 +962 @@
         return jsNull();
     }
+
+    DynamicGlobalObjectScope globalObjectScope(exec, exec->globalData().dynamicGlobalObject ? exec->globalData().dynamicGlobalObject : scopeChain->globalObject());
 
     Register* argv = oldEnd;
@@ -992 +1016 @@
         return jsNull();
     }
+
+    DynamicGlobalObjectScope globalObjectScope(exec, exec->globalData().dynamicGlobalObject ? exec->globalData().dynamicGlobalObject : scopeChain->globalObject());
 
     EvalCodeBlock* codeBlock = &evalNode->byteCode(scopeChain);
@@ -3949 +3975 @@
 }
 
-const Register* Machine::firstCallFrame(const Register* callFrame)
-{
-    const Register* first = 0;
-    for (const Register* frame = callFrame; frame; frame = stripHostCallFrameBit(frame[RegisterFile::CallerRegisters].r()))
-        first = frame;
-    return first;
-}
-
 Register* Machine::callFrame(ExecState* exec, InternalFunction* function) const
 {

trunk/JavaScriptCore/VM/Machine.h

@@ -104 +104 @@
         void retrieveLastCaller(ExecState* exec, int& lineNumber, intptr_t& sourceID, UString& sourceURL, JSValue*& function) const;
         
-        static const Register* firstCallFrame(const Register* callFrame);
         static ScopeChainNode* scopeChain(const Register* r) { return r[RegisterFile::ScopeChain].scopeChain(); }
         static CodeBlock* codeBlock(const Register* r) { return r[RegisterFile::CodeBlock].codeBlock(); }

trunk/JavaScriptCore/kjs/ExecState.h

@@ -44 +44 @@
 
         // Global object in which execution began.
-        JSGlobalObject* dynamicGlobalObject()
-        {
-            return Machine::scopeChain(Machine::firstCallFrame(this))->globalObject();
-        }
+        JSGlobalObject* dynamicGlobalObject();
 
         // Global object in which the currently executing code was defined.

trunk/JavaScriptCore/kjs/JSGlobalData.cpp

@@ -92 +92 @@
     , parser(new Parser)
     , head(0)
+    , dynamicGlobalObject(0)
     , isSharedInstance(isShared)
     , clientData(0)

trunk/JavaScriptCore/kjs/JSGlobalData.h

@@ -99 +99 @@
 
         JSGlobalObject* head;
+        JSGlobalObject* dynamicGlobalObject;
 
         bool isSharedInstance;

trunk/JavaScriptCore/kjs/JSGlobalObject.h

@@ -331 +331 @@
     }
 
+    inline JSGlobalObject* ExecState::dynamicGlobalObject()
+    {
+        if (this == lexicalGlobalObject()->globalExec())
+            return lexicalGlobalObject();
+
+        // For any ExecState that's not a globalExec, the 
+        // dynamic global object must be set since code is running
+        ASSERT(globalData().dynamicGlobalObject);
+        return globalData().dynamicGlobalObject;
+    }
+    
 } // namespace JSC