Changeset 37323 in webkit for trunk/JavaScriptCore/VM/Machine.cpp

Timestamp:

Oct 5, 2008, 7:48:08 PM (17 years ago)

Author:

[email protected]

Message:

2008-10-05 Maciej Stachowiak <​[email protected]>

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.

File:

• trunk/JavaScriptCore/VM/Machine.cpp (modified) (6 diffs)

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
 {