[JSC] Remove DeprecatedCallFrameForDebugger

https://bugs.webkit.org/show_bug.cgi?id=239045

Reviewed by Devin Rousso.

We should not enlarge sizeof(JSGlobalObject) by having DeprecatedCallFrameForDebugger which is only used for Debugger, and it is used
only when we have an error when evaluating top-level SyntaxError. This patch removes it: we introduce EmptyTopLevelCallFrameForDebugger
which can be constructed on stack and we use it instead of DeprecatedCallFrameForDebugger.

* Source/JavaScriptCore/debugger/Debugger.cpp:
(JSC::Debugger::updateCallFrame):
(JSC::EmptyTopLevelCallFrameForDebugger::EmptyTopLevelCallFrameForDebugger):
(JSC::EmptyTopLevelCallFrameForDebugger::asCallFrame):
(JSC::Debugger::exception):
* Source/JavaScriptCore/debugger/DebuggerCallFrame.cpp:
(JSC::DebuggerCallFrame::create):
(JSC::DebuggerCallFrame::positionForCallFrame):
* Source/JavaScriptCore/interpreter/CallFrame.cpp:
(JSC::CallFrame::convertToStackOverflowFrame):
(JSC::CallFrame::initDeprecatedCallFrameForDebugger): Deleted.
* Source/JavaScriptCore/interpreter/CallFrame.h:
(JSC::CallFrame::isEmptyTopLevelCallFrameForDebugger const):
(JSC::CallFrame::isDeprecatedCallFrameForDebugger const): Deleted.
* Source/JavaScriptCore/interpreter/Interpreter.cpp:
(JSC::Interpreter::notifyDebuggerOfExceptionToBeThrown):
* Source/JavaScriptCore/runtime/JSGlobalObject.cpp:
(JSC::JSGlobalObject::init):
(JSC::JSGlobalObject::deprecatedCallFrameForDebugger): Deleted.
* Source/JavaScriptCore/runtime/JSGlobalObject.h:
* Source/JavaScriptCore/runtime/VM.cpp:
(JSC::VM::throwException):

Canonical link: https://commits.webkit.org/249603@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@292830 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/JavaScriptCore/ChangeLog

@@ -1,3 +1,37 @@
+2022-04-13  Yusuke Suzuki  <ysuzuki@apple.com>
+
+        [JSC] Remove DeprecatedCallFrameForDebugger
+        https://bugs.webkit.org/show_bug.cgi?id=239045
+
+        Reviewed by Devin Rousso.
+
+        We should not enlarge sizeof(JSGlobalObject) by having DeprecatedCallFrameForDebugger which is only used for Debugger, and it is used
+        only when we have an error when evaluating top-level SyntaxError. This patch removes it: we introduce EmptyTopLevelCallFrameForDebugger
+        which can be constructed on stack and we use it instead of DeprecatedCallFrameForDebugger.
+
+        * debugger/Debugger.cpp:
+        (JSC::Debugger::updateCallFrame):
+        (JSC::EmptyTopLevelCallFrameForDebugger::EmptyTopLevelCallFrameForDebugger):
+        (JSC::EmptyTopLevelCallFrameForDebugger::asCallFrame):
+        (JSC::Debugger::exception):
+        * debugger/DebuggerCallFrame.cpp:
+        (JSC::DebuggerCallFrame::create):
+        (JSC::DebuggerCallFrame::positionForCallFrame):
+        * interpreter/CallFrame.cpp:
+        (JSC::CallFrame::convertToStackOverflowFrame):
+        (JSC::CallFrame::initDeprecatedCallFrameForDebugger): Deleted.
+        * interpreter/CallFrame.h:
+        (JSC::CallFrame::isEmptyTopLevelCallFrameForDebugger const):
+        (JSC::CallFrame::isDeprecatedCallFrameForDebugger const): Deleted.
+        * interpreter/Interpreter.cpp:
+        (JSC::Interpreter::notifyDebuggerOfExceptionToBeThrown):
+        * runtime/JSGlobalObject.cpp:
+        (JSC::JSGlobalObject::init):
+        (JSC::JSGlobalObject::deprecatedCallFrameForDebugger): Deleted.
+        * runtime/JSGlobalObject.h:
+        * runtime/VM.cpp:
+        (JSC::VM::throwException):
+
 2022-04-13  Chris Dumez  <cdumez@apple.com>
 
         Replace AtomString(const char*) with AtomString::fromLatin1(const char*)

Source/JavaScriptCore/debugger/Debugger.cpp

@@ -1035,6 +1035,26 @@ JSC::JSValue Debugger::exceptionOrCaughtValue(JSC::JSGlobalObject* globalObject)
     return { };
 }
 
+class EmptyTopLevelCallFrameForDebugger {
+public:
+    EmptyTopLevelCallFrameForDebugger(JSGlobalObject* globalObject)
+    {
+        CallFrame* callFrame = asCallFrame();
+        callFrame->setCodeBlock(nullptr);
+        callFrame->setCallerFrame(CallFrame::noCaller());
+        callFrame->setReturnPC(nullptr);
+        callFrame->setArgumentCountIncludingThis(1);
+        callFrame->setThisValue(globalObject->globalThis());
+        callFrame->setCallee(globalObject->globalCallee());
+        ASSERT(callFrame->isEmptyTopLevelCallFrameForDebugger());
+    }
+
+    CallFrame* asCallFrame() { return CallFrame::create(m_values); }
+
+private:
+    Register m_values[CallFrame::headerSizeInRegisters + /* thisValue */ 1] { };
+};
+
 void Debugger::exception(JSGlobalObject* globalObject, CallFrame* callFrame, JSValue exception, bool hasCatchHandler)
 {
     if (m_isPaused)
@@ -1056,11 +1076,21 @@ void Debugger::exception(JSGlobalObject* globalObject, CallFrame* callFrame, JSV
         setSteppingMode(SteppingModeEnabled);
     }
 
+    // When callFrame is nullptr, we are throwing an error without JS call frames.
+    // This can happen when program throws SyntaxError without evaluation.
+    EmptyTopLevelCallFrameForDebugger emptyCallFrame(globalObject);
+    bool callFrameWasNull = !callFrame;
+    if (callFrameWasNull)
+        callFrame = emptyCallFrame.asCallFrame();
+
     m_hasHandlerForExceptionCallback = true;
     m_currentException = exception;
     updateCallFrame(globalObject, callFrame, AttemptPause);
     m_currentException = JSValue();
     m_hasHandlerForExceptionCallback = false;
+
+    if (callFrameWasNull)
+        m_currentCallFrame = nullptr;
 }
 
 void Debugger::atStatement(CallFrame* callFrame)

Source/JavaScriptCore/debugger/DebuggerCallFrame.cpp

@@ -66,7 +66,7 @@ Ref<DebuggerCallFrame> DebuggerCallFrame::create(VM& vm, CallFrame* callFrame)
         return adoptRef(*new DebuggerCallFrame(vm, callFrame, emptyFrame));
     }
 
-    if (callFrame->isDeprecatedCallFrameForDebugger()) {
+    if (callFrame->isEmptyTopLevelCallFrameForDebugger()) {
         ShadowChicken::Frame emptyFrame;
         RELEASE_ASSERT(!emptyFrame.isTailDeleted);
         return adoptRef(*new DebuggerCallFrame(vm, callFrame, emptyFrame));
@@ -320,6 +320,8 @@ TextPosition DebuggerCallFrame::currentPosition(VM& vm)
 TextPosition DebuggerCallFrame::positionForCallFrame(VM& vm, CallFrame* callFrame)
 {
     LineAndColumnFunctor functor;
+    if (!callFrame)
+        return TextPosition(OrdinalNumber::fromOneBasedInt(0), OrdinalNumber::fromOneBasedInt(0));
     StackVisitor::visit(callFrame, vm, functor);
     return TextPosition(OrdinalNumber::fromOneBasedInt(functor.line()), OrdinalNumber::fromOneBasedInt(functor.column()));
 }

Source/JavaScriptCore/interpreter/CallFrame.cpp

@@ -40,16 +40,6 @@
 
 namespace JSC {
 
-void CallFrame::initDeprecatedCallFrameForDebugger(CallFrame* globalExec, JSCallee* globalCallee)
-{
-    globalExec->setCodeBlock(nullptr);
-    globalExec->setCallerFrame(noCaller());
-    globalExec->setReturnPC(nullptr);
-    globalExec->setArgumentCountIncludingThis(0);
-    globalExec->setCallee(globalCallee);
-    ASSERT(globalExec->isDeprecatedCallFrameForDebugger());
-}
-
 bool CallFrame::callSiteBitsAreBytecodeOffset() const
 {
     ASSERT(codeBlock());
@@ -338,7 +328,7 @@ const char* CallFrame::describeFrame()
 
 void CallFrame::convertToStackOverflowFrame(VM& vm, CodeBlock* codeBlockToKeepAliveUntilFrameIsUnwound)
 {
-    ASSERT(!isDeprecatedCallFrameForDebugger());
+    ASSERT(!isEmptyTopLevelCallFrameForDebugger());
     ASSERT(codeBlockToKeepAliveUntilFrameIsUnwound->inherits<CodeBlock>(vm));
 
     EntryFrame* entryFrame = vm.topEntryFrame;

Source/JavaScriptCore/interpreter/CallFrame.h

@@ -240,8 +240,6 @@ namespace JSC  {
         void setCallerFrame(CallFrame* frame) { callerFrameAndPC().callerFrame = frame; }
         inline void setScope(int scopeRegisterOffset, JSScope*);
 
-        static void initDeprecatedCallFrameForDebugger(CallFrame* globalExec, JSCallee* globalCallee);
-
         // Read a register from the codeframe (or constant from the CodeBlock).
         Register& r(VirtualRegister);
         // Read a register for a known non-constant
@@ -301,7 +299,8 @@ namespace JSC  {
         static int offsetFor(size_t argumentCountIncludingThis) { return CallFrameSlot::thisArgument + argumentCountIncludingThis - 1; }
 
         static CallFrame* noCaller() { return nullptr; }
-        bool isDeprecatedCallFrameForDebugger() const
+
+        bool isEmptyTopLevelCallFrameForDebugger() const
         {
             return callerFrameAndPC().callerFrame == noCaller() && callerFrameAndPC().returnPC == nullptr;
         }

Source/JavaScriptCore/interpreter/Interpreter.cpp

@@ -770,7 +770,8 @@ void Interpreter::notifyDebuggerOfExceptionToBeThrown(VM& vm, JSGlobalObject* gl
         // https://bugs.webkit.org/show_bug.cgi?id=121754
 
         GetCatchHandlerFunctor functor;
-        StackVisitor::visit(callFrame, vm, functor);
+        if (callFrame)
+            StackVisitor::visit(callFrame, vm, functor);
         HandlerInfo* handler = functor.handler();
         ASSERT(!handler || handler->isCatchHandler());
         bool hasCatchHandler = !!handler;

Source/JavaScriptCore/runtime/JSGlobalObject.cpp

@@ -743,8 +743,6 @@ void JSGlobalObject::init(VM& vm)
     JSCallee* globalCallee = JSCallee::create(vm, this, globalScope());
     m_globalCallee.set(vm, this, globalCallee);
 
-    CallFrame::initDeprecatedCallFrameForDebugger(JSGlobalObject::deprecatedCallFrameForDebugger(), globalCallee);
-
     JSCallee* stackOverflowFrameCallee = JSCallee::create(vm, this, globalScope());
     m_stackOverflowFrameCallee.set(vm, this, stackOverflowFrameCallee);
 
@@ -2358,11 +2356,6 @@ void JSGlobalObject::visitChildrenImpl(JSCell* cell, Visitor& visitor)
 
 DEFINE_VISIT_CHILDREN_WITH_MODIFIER(JS_EXPORT_PRIVATE, JSGlobalObject);
 
-CallFrame* JSGlobalObject::deprecatedCallFrameForDebugger()
-{
-    return CallFrame::create(m_deprecatedCallFrameForDebugger);
-}
-
 SUPPRESS_ASAN void JSGlobalObject::exposeDollarVM(VM& vm)
 {
     RELEASE_ASSERT(g_jscConfig.restrictedOptionsEnabled && Options::useDollarVM());

Source/JavaScriptCore/runtime/JSGlobalObject.h

@@ -298,8 +298,6 @@ class JSGlobalObject : public JSSegmentedVariableObject {
 public:
     template<typename T> using Initializer = typename LazyProperty<JSGlobalObject, T>::Initializer;
 
-    Register m_deprecatedCallFrameForDebugger[CallFrame::headerSizeInRegisters];
-
     WriteBarrier<JSObject> m_globalThis;
 
     WriteBarrier<JSGlobalLexicalEnvironment> m_globalLexicalEnvironment;
@@ -1096,8 +1094,6 @@ class JSGlobalObject : public JSSegmentedVariableObject {
 
     const GlobalObjectMethodTable* globalObjectMethodTable() const { return m_globalObjectMethodTable; }
 
-    JS_EXPORT_PRIVATE CallFrame* deprecatedCallFrameForDebugger();
-
     static bool supportsRichSourceInfo(const JSGlobalObject*) { return true; }
 
     static JSGlobalObject* deriveShadowRealmGlobalObject(JSGlobalObject* globalObject)

Source/JavaScriptCore/runtime/VM.cpp

@@ -898,9 +898,6 @@ Exception* VM::throwException(JSGlobalObject* globalObject, Exception* exception
     }
 
     CallFrame* throwOriginFrame = topJSCallFrame();
-    if (!throwOriginFrame)
-        throwOriginFrame = globalObject->deprecatedCallFrameForDebugger();
-
     if (UNLIKELY(Options::breakOnThrow())) {
         CodeBlock* codeBlock = throwOriginFrame ? throwOriginFrame->codeBlock() : nullptr;
         dataLog("Throwing exception in call frame ", RawPointer(throwOriginFrame), " for code block ", codeBlock, "\n");